ne ea ee ee ee eens ripen i no ip parre Serene , Xs A DUANE: % er ne es es eer eer Se Ree ee eee a Selah eee ene ne ap efortiid CornelVAniversity Library BOUGHT WITH THE INCOME “FROM THE SAGE ENDOWMENT FUND THE GIFT OF Henry W. Saqe 1891 PRILENE: secsiernienien i ae etaae 6896-1 WORKS OF EDWARD WEGMANN, C.E., PUBLISHED BY JOHN WILEY & SONS. The Water-supply of the City of New York from 1658 to 1895. Profusely illustrated with half-tones and figures in the text, and folding-plates. 4to, cloth, $10.00. The Design and Construction of Dams. Including Masonry, Earth, Rock-fill, Timber and Steel Structures; also, the Principal Types of Movable Dams, Profusely illustrated with 120 figures in the text and 133 plates, including folders and half-tones. 4to, cloth, $6.00, TO ON NN Me ie ‘NVG NOLOWO MAN THE DESIGN AND CONSTRUCTION OF DAMS INCLUDING MASONRY, EARTH, ROCK-FILL, TIMBER, AND STEEL STRUCTURES ALSO THE PRINCIPAL TYPES OF MOVABLE DAMS BY EDWARD WEGMANN, C.E. M. AM. SOC. C. E. Author of “ The Water-Supply of the City of New York, 1658-1895” FIFTH EDITION, REVISED AND ENLARGED, FIRST THOUSAND NEW YORK JOHN WILEY & SONS Lonpon: CHAPMAN & HALL, LimitTEpD 1907 $\o6l G@obw A 217287. CopyriGHT, 1899, 1907, BY EDWARD WEGMANN. The Srientifir Preas Robert Drummond and Company Nem York PREFACE TO THE FIRST EDITION. THE great advantages to be derived from large storage reservoirs, built for regulating the flow of a river, for irrigation purposes, or for domestic water supply, have led within recent years to the construction of a large number of such works in various parts of the world. Where water having great depth is to be retained, it would be extremely hazard- ous to rely on earthen dams, as numerous failures of such works have been recorded, and walls of masonry are, therefore, employed. The successful completion of the Furens Dam (164 feet high) in 1866 was soon followed by that of many similar structures in France, Algiers, and Italy. In the United States a concrete dam (170 feet high) is being built near San Francisco; the Sodom Dam (70 feet high) has been commenced on the East Branch of the Croton River; and the Quaker Bridge Dam, which will surpass all existing dams in height, has been designed to form an immense storage reservoir for the city of New York. While the practical importance of the subject of masonry dams seems to be steadily growing, the engineer who may be entrusted with the design of such works will find the theoretical study of the best form of profile for a masonry dam very disheartening. How widely the types proposed by eminent engineers differ from each other is shown on Plate A, page 43. The theory of masonry“dams is based upon a few simple principles and conditions; the mathematics, however, to which they give rise, when applied to the design of an economical profile, are rather appalling. Thus, if we follow the methods of the French engineers Sazilly and Delocre, we have to solve lengthy equations, some of them of the sixth degree. Moreover, there is always an uncertainty which equation is to be used, and the only way of determining this is by trial. If we wish to employ the method of Prof. Rankine, but change the data assumed by him, we have to make trials with the subtangent of a logarithmic curve. In contradistinction to these scientific methods, we find prominent engineers recommending trial calculations as the best practical solution of the problem. The writer, when detailed by the Chief Engineer of the New Croton Aqueduct to make calculations for the proposed Quaker Bridge Dam, the height of which is to be 270 feet, after studying the existing methods of designing profiles and finding them for various reasons inapplicable to the case in view, finally arrived at the equations given in this book. They are easy to solve, being, with the exception of one cubic equation, of the first or second degree. The theoretical section of the Quaker Bridge Dam was calculated by these equations. As the construction of this gigantic dam, iii iv PREFACE. which is likely to be commenced soon, may lead many persons to inquire how its pro- file was determined, the writer has thought that a book giving the details of the method employed, and information about masonry dams in general, might be of interest and practical value to engineers. It is with this view that the present work has been un- dertaken. The text has been illustrated by numerous Plates and Tables, showing the form and strength of the various profiles discussed. Data of forty-four existing masonry dams have been collected in Table XXIII. ‘ The investigations given in Chapter IV., relating to the effect of the weight of masonry upon the form of profile and the calculations for inclined joints, were sug- gested in connection with the proposed Quaker Bridge Dam by Mr. B. S. Church, Chief Engineer, and Mr. A. Fteley, Consulting Engineer. In the preparation of this book the writer has been assisted by some of the en- gineers of the New Croton Aqueduct, who have become interested in these studies, and he wishes to express herewith his thanks to Mr. H. C. Alden and Mr. M. A. Viele, who have helped him to calculate the Tables, and to Mr. G. Bonanno and Mr. I. A. Shaler, who have rendered valuable aid in making the drawings and in collecting information about existing dams. E. W., Jr. New York, April, 1888. PREFACE TO THE THIRD EDITION. SINCE the first edition of this work was published, the project of constructing a dam across the Croton Valley near the Quaker Bridge has been abandoned, another site, about 1$ miles further up-stream, having been selected for the proposed struc- ture. As the profile adopted for this reservoir wall is, however, practically the same as the one designed for the proposed Quaker Bridge Dam, the studies made for the latter, which are given in this book, may still be of interest. The only change which has been made, therefore, in the present edition of this work has been to add a new Chapter and additional Plates, in order to bring the descriptions given of dams constructed up to date. E. W., Jr. New York, Sept. 1, 1893. PREFACE TO THE FOURTH EDITION. THE first Part of this work was published in 1888 as a treatise on “ The Design and Con- struction of Masonry Dams.” It contains the results of the studies made by the author while engaged in making calculations for the design of the proposed Quaker Bridge Dam, and in- formation about high masonry dams built in various countries. The book passed through three editions, the only changes made being the addition of an extract from the report of the ex- perts who investigated the designs for the Quaker Bridge Dam, and of descriptions of dams recently constructed, in order to bring the information on this subject up to date. In the present edition the work has been enlarged so as to include the whole subject of dams, viz., masonry, earth, rock-fill, and timber structures, and, also, the principal types of movable dams. The author has endeavored to add to the practical interest of the original book, which forms Part I of the present work, by inserting half-tones in the text, giving detailed descrip- tions and drawings of some of the high masonry dams recently built to form storage reservoirs for the water-supply of the city of New York, and by placing in the Appendix the specifica- tions for the New Croton Dam, which will be by far the highest structure of its kind. To illustrate fully the manner in which the profile of this dam was calculated by the method explained in Part I, Chapter III, a practical example of the application of the equations used for this purpose has been given in the Appendix. - The subjects of earth, rock-fill, and timber dams are discussed in Part II. The principal types of movable dams are described in Part III. Since 1839 internal navigation in France has been much improved by means of structures of this kind. Thus far only a few movable dams have been built in the United States. As this subject has been attracting much atten- tion in America of late, the author has thought it advisable to include it in the present edition. The information given in this volume has been gathered from many sources. The author- ities consulted are given in the Appendix (p. 239). The sources from which the illustrations in the book were obtained are generally mentioned in the text. The half-tones of the Furens and Vyrnwy dams were reproduced from plates contained in a report on high masonry dams, by Mr. George W. Rafter, which was included in the Annual Report for 1897 of the Engineer and Surveyor of the State of New York. In Plate B, photographs of the Gileppe Dam, which were kindly loaned the author by Mr. Alphonse Fteley, the Chief Engineer of the Aqueduct Commission of New York, are reproduced. Figs. 39 and 54 were taken from Mahan’s “Civil Engineering.” Figs. 19 to 21 and 23 were obtained from the 18th Annual Report of the U. S. Geological Survey. The author wishes to acknowledge here his obliga- tion to Mr. F. H. Newell, the hydrographer of this survey, who kindly furnished him with electrotypes of all the plates and figures contained in the reports of the U. S. Geological Sur- Vv vi PREFACE. vey which have been reproduced in this book. He wishes, also, to express his thanks to Mr. Edward A. Bond, State Engineer of New York, who enabled him to obtain electrotypes of Plates A and C. The author hopes that the new matter added to the book will increase its usefulness and that it may be of practical help to members of the profession who cannot avail themselves of the information contained in large technical libraries. E. W. New York, July 1, z8yg. THE first impressions of the Fourth Edition having been exhausted, the writer has added to this edition descriptions of the Rosetta, Damietta, Assuan, and Assiout dams across the Nile and, also, a short account of the failure of the Austin Dam. E. W. New York, April 1, 1904. PREFACE TO THE FIFTH EDITION. In preparing the Fifth Edition of this book, the whole work has been thoroughly revised with the view of bringing the information contained as much as possible up to date. The newest theories proposed for the design of masonry dams have been men- tioned in the Introduction. The chapter on the construction of masonry dams has been entirely rewritten. Descriptions of all important dams built or in course of construction, of which the author could find any record, have been given, and in the cases of the New Croton Dam, the highest masonry dam thus. far built, and of other noteworthy reservoir walls the construction: has been described -with considerable detail. The text has been illustrated by numerous plates and figures. Among the new matter added to the book are descriptions of steel and concrete-steel dams, high earth dams, Stoney sluice-gates, and rolling dams. In the present edition the work contains 93 pages of reading-matter, 39 plates, and 45 figures more than appeared in the Fourth Edition. The information given has been gathered from many sources, partly from printed records and partly by correspondence. The author wishes to acknowledge here his indebted- ness to the many engineers who have assisted him by supplying desired data about dams, and he has endeavored to give due credit for such assistance in the text of the book. The preparation of this edition has involved much work, and the author hopes that the many hours spent on the revision may have added to the practical value of the book. E. W. CONTENTS. PART I. DESIGN AND CONSTRUCTION OF MASONRY DAMS. CHAPTER I. PAGE INTRODUCTION, ; ‘i ‘ ‘ * = CHAPTER II. DISTRIBUTION OF PRESSURE IN A WALL OF Masonry, . i ‘ ‘i é : 3 i * ? es ‘i . It CHAPTER III. THEORETICAL PROFILES, i ee ee Sa es See, el a ee, ee SE OE te go, CHAPTER IV, Various APPLICATIONS OF EQUATIONS (1) TO (14), : de te Ree SRY. po rae ae OR: Se wee, TA RS CHAPTER V. PRACTICAL PROFILES, 5 e 8 , ‘ bs ‘ os Gi ae) ES Ry ts “et a cae OH oa. HOA CHAPTER VI.. CONSTRUCTION, . é . ‘i ‘ 3 é ‘ F ‘ i ‘ ‘ é ; ‘ . “i ‘ ‘i . - 46 CHAPTER VII. SPANISH Dams, . 4 5 ‘ 2 3 3 : é ; é : . 3 3 : A ‘ . : 3 $ ‘Se CHAPTER VIII. Frenco Dams, Oe Ge a Sho ec = s Sefe eS Me a we CHAPTER IX. Dams IN Various Parts oF EvROPE, a <“¢ : 5 : | ne oa a Sa » 79 CHAPTER X. Dams IN ALGIERS, . . . . . se tS ewe ws IQ CHAPTER XI. Dams IN EGYPT, i ‘ F a : j é ‘ : , ‘ é ‘ 5 é "i : 5 ‘ « LOT CHAPTER XII. Dams IN AsIA AND AUSTRALASIA, - : ‘ - ‘ : 3 é ‘ . . ° a 5 : . 16 CHAPTER XIII. AMERICAN Dams, 5 ‘ ‘ ‘ ‘ ‘ a : j , * s s 5 3 ae mi. 46 ‘ ‘ . 128 CHAPTER XIV. ° REINFORCED CONCRETE DAMS, . : ‘: : é ; di . 4 ; 7 5 . 7 5 ‘ : . 210 vii vill CONTENTS. — PART II. EARTHEN, ROCK-FILL, TIMBER, AND STEEL DAMS, CHAPTER I. PAGE EARTHEN Dams, CHAPTER II. Dams MADE BY THE HypravLic Process, Be Bee OR oS SR ae Se we. nS CHAPTER III. Rocx-Fitt Dams, es He, oa, ay. PR Ie ceri, Khel GO) at a fa S oh oe. as. “eS ee. Yee 206 CHAPTER IV TimBer Dams, of aie rie de. ae Be Saye Se Gp, ah gy “eto SB. G0: “di ee Si oie. A280 CHAPTER V. STEEL Dams, 3 ‘ ‘ . ‘ é é * . ‘ é 2 ‘ ‘ . . 3 e e . o » 294 PAKT If, MOVABLE DAMS. CHAPTER I. FRAME DAMS) 3 Ge SRR ww Se OE CHAPTER II. SHUTTER Dams, ‘ ‘ ‘ é : é ‘ i z ‘ « ‘ ‘a * * ‘ % * - 325 CHAPTER III. DAMS WITH BEAR-TRAP GATES, a. 1% : 8 &@ 2 & & w@ © HK Bae CHAPTER IV. STONEY ROLLER SLUICE-GATES, ROLLING Dams, AND BUTTERFLY Dams, . . . . . . . ‘i + 351 CHAPTER V. Recent Movasie Dams, We ERR se ee ee le ls 383 APPENDIX. SPECIFICATIONS FOR THE New Croton Dam, . «© . ee et el 88 Notrs A, B, anv C, a BR) Ge Se a Rew. BF TasLrs I TO XXV, ee a a ee!) CALCULATION OF THEORETICAL PROFILE No. 6, - ‘ ‘ ‘ ¥ é : ‘ i r Z - 403 BIBLIOGRAPHY, . x 5 . 5 i é ‘ ‘ ‘i ‘ a * é a a A Ci ‘ : + 405 INDEX, is. as i. : oh ok io) RR ceo eh cle’ ee ae LIST OF PLATES. Frontispiece. New Croton Dam. Plate A. Comparison of Profiles...........secseececsvece Sia GSWEw Paws Ua Ea Slee gwen oe Page 43 Be Murens: Damt ice cave den sevsvens a smeraa ea nanseeeen sta gneen seeabauus MASAO ARE uee awe os 67 C. Gileppe Dam. ............ SSeS Galore eases emcees e ES Gectaereis ORS Snare eG me cues ee euceeraane a aoe fe 83 D. Vyrnwy Dam. ..........0 eee eine Far ee re ee re ee ee tr ee 185 By Agsuan). Dams oy ora cdenawsdinaaead dieveaasieone See MAREE R AAW orate me eRe aE E Ce Aimiecgieve © uta ereiwiew eaieil s€ 105 FF. Assuan Daitiv ages a1 deine auc saiene Rete sed Sk VASES SES TURTON tee RAM ER Eee he aR TAS of, | OF Gs ASSIOUE: Datii.s ciccma cased eas sama dsm aameded Palomas nema ew aieeien iGUGmeiE eee Sue ae ff TU Hi. ASsiGuto Dams s cciaiveicaxiuiwaneexs aleyeaiuns oa gape ese oceuesaer esse dnsa vee tieee Recurrent ee 1. San. Mateo Das cick vec conten cae ewesnevesaareeels ces oave suns snasesenewaaeuw senaebe ae nes «131 J. Bear Valley Dam..... Fe Redese pies Sars GOR AARUM ALIS OORT as SRSA EERE Rae ATES ek. “org Ki Sweetwater Dams csi. vec scares dens arene qulagmeaecoess Mee eR ee qu peieie Sasa dla cud auinge dames oe 99 Ts Sociatl. BP Atiied ara sia araus oad rn cabeen sake eek okie oe toeutsne ws oanie sentence amen ane sane Ot pa IMG Witieus: D ainis:::dscs ele scare eich ned varemmiee sak Soe o es aa WOR ha KERN Gawain ae aads Sannnaths oe 46 N; New Croton: Dats. osc0 oe si sceaaicsacasadenss paavagg anes Maven Dew aGra Eee be Heise PER REIS 8 tf 765 ©. New Croton, Dam in; Constcions .c.aciase tncomcagad cnc peenald ene sans aba ames membre ee ‘e167 Py. es Pi Lr cece Rt cor ee rere re scree oe or Q. * fe ee es {fe baw Oeehe ka Rae eeas Esse cee oe see amen eee MaweES a whee ee eC 93 R, * ee oe “Sue fC Apaadadehned tease deauae awe eames aasnea ras hippaee oe Eee ts “179 Ss.“ ae eS ES pearatesisaa lee tae Rinnas eran Hea Rea aCEA LER ROM RARE EERE ‘181 “De Wachusett Dams: so css -sasitediaa tele Ginna saalea gecaiation Pudigus aa bau eign He Sie Ne miaNeets “e987 IU. Shoshone Dam yi so0%ceca sede ves oaeenaeless teehee ss HOES EE RE aSMEaWeS § OERaD EOS TEMES ‘205 Ve Jiintata D ai c5.¢ caine Sr eadiegaw Panseueete MEN IMacaeR Lek aemeN Ae Ga a wMNE kebae eee ‘€ 215 Wi, Juiniats; Dam... oo aacsadhiaeie tea carralenedu bos eens awa tne eaaind ea Rees Me RneE ete OoateieE ee 219 Ae a Mesa: Dan ss sew Spain te ainacan se eesulaisany selon scoeous Jee aasy te AOR aeI os sHaRe ena ‘* 249 Vi Zint Date a vgscvcar dewey cea dimase ths eotewts sae Pe ET ea ee Mane Cee cane ewe iaae e -B6r Zico BSCONGIGG: DAM: oci4 idan he aunadrndemeneinadaemd Rabew ees Pins Qarcaiee dane’ sarees aya eave eitatanas *¢ 267 AA; Lower Otay Dam. scccsage eco naay ihe gpreaedn ca wedi nay dede Gale eipae banged ne eReEs arSaapeirat of Bar BB; Ash. Fork and Redridge Dams; 5.002 c00cvateies onsaanace cae nsdaan yealsadee ena daaeene ec enwaw “© 295 CC, Haser Lake Dative s.:c00 c120s tea eenecaeaad aa0 Solos eRe SRE wE awe Le eeea eS wade ae ** 299 DD). ‘Big: Sandy River Wane.) sanicsds save eh aed.0 dara ote pee EANAG Sdig ewes MasawiOd eae Ree TE oe eQle Se “git BEY Besa Dam cup occa amaan cea agiemiig see peweme wale wes« (SevGeede Gusset as Bie ROS ean isis Sf 358 FR. Hagneck: Dain. 9 sis 2 cundeedsa gsouene'ssiedsiasaw’ Sagi weeds Heb Seietiaees pe ertine +e eA Namie Halzes “* 355 GG. Rolling Dam at Schweinfurt ........... eee eee ewes oS RRS REING EE Hsia dud g ea Gin eA Isinae az “* 350 Plate I. De Sazilly’s Profile-type. Plate XVII. Practical Profile No. 1. II. Delocre’s Profile-type. XVIII. Practical Profile No. 2. III. Prof. Rankine’s Profile-type. XIX. Practical Profile No. 3. IV. Comparison of Rankine’s Profile with the Theo- XX. Stability of Practical Profile, No. 3, found by _ retical Profile. Graphic Statics. V. Krantz’s Profile-type. XXTI. Almanza Dam. VI. Prof. Harlacher’s Profile-type. XXII. Alicante Dam. VII. Crugnola’s Profile-type. XXIII. Elche Dam. VIII. Theoretical Profile No. 1. XXIV. Puentes Dam. IX. Theoretical Profile No. 2. XXV. Val de Infierno Dam. X. Comparison of Theoretical Profiles. XXVI. Nijar Dam. XI. Theoretical Profile No. 5 with Inclined Joints. XXVII. Lozoya Dam. XII. Theoretical Profile No. 5, modified by Bouvier’s XXVIII. Villar Dam. formule. XXIX. Hijar Dam. XIII. Theoretical Type No. I. XXX. Lampy Dam. XIV. Practical Type No. 1. XXXI. Vioreau Dam. XV. Theoretical Type No. II. XXXII. Bosmelea Dam, XVI. Practical Type No. 2. XXXIII. Glomel Dam. ix x Plate XXXIV. XXXV. XXXVI. XXXVI. XXXVIII. XXXIX. XL. XLI. XLII. XLII. XLIV. XLV. XLVI. XLVII. XLVIII. XLIX. L. LI. LII. LIT. LIV. LV. LVI. LVII. LVITI. LIX. Lx. LXI. LXTI. LXIII. LXIV, LXV. LXVI. LXVII. LXVIII. LIST OF Gros-Bois Dam. Zola Dam. Furens Dam. Ternay Dam. Ban Dam. Verdon Dam. Bouzey Dam. Pont Dam. Chartrain Dam. Mouche Dam. Turdine and Miodeix Dams, Cagliari Dam. Gorzente Dam. Komotau and Lagolungo. Gileppe Dam. Vyrnwy Dam. Habra Dam. Tlelat Dam. Djidionia Dam. Gran Cheurfas Dam. Hamiz Dam. Assuan Dam. Poona Dam. Tansa Dam. Periar Dam. Geelong Dam. Tytam Dam. Boyd’s Corners Dam, Bridgeport Dam. Wigwam Dam. San Mateo Dam. Bear Valley Dam. Sweetwater Dam. Hemmet Dam. Colorado Dam. PLATES. Plate LXIX. LXxX. LXXI. LXXII. LXXIII. LXXIV. LXXV. LXXVI, LXXVII. LXXVIII. LXXIX. LXXX. LXXXI. LXXXII. LXXNIII. LXXXIV. LXXXV. LXXXVI. LXXXVII. LXXXVIII. LXXXIX. XC. XCI. XCII. XCIII. XCIV. XCV. XCVI. XCVII. XCVIII. XCIX. Cc. Sodom Dam. Titicus Dam, Plan. Titicus Dam, Elevation. Titicus Dam, Profile. Titicus Dam, Profile at Gate House. Titicus Dam, Overflow. Titicus Dam, Flume. Old Croton Dam. Quaker Bridge Dam, Department of Pub- lic Works’ Plan. Quaker Bridge Dam, Aqueduct Commis- sioners’ Plan. Quaker Bridge Dam, Experts’ Plan. New Croton Dam, Plan. New Croton Dam, Elevation. New Croton Dam, Profile. New Croton Dam, Overflow. Wachusett and Spier Falls Dams. Details of Wachusett Dam. Boonton Dam. Boonton and Spier Falls Overflows. Roosevelt and Cheesman Lake Dams. Shoshone and Pathfinder Dams. Cross River Dam. Croton Falls Dam. Outlet Tower, Vehar Reservoir, Bombay. Yarrow Dam, Liverpool Water-werks. Earthen Dams for Water-works of New York. Belle Fourche Dam. Crib-dams in Pennsylvania. Holyoke Dam. Ash Fork Steel Dam. Redridge Steel Dam. Stoney Roller Sluice-gate for Beznau Dam. LIST OF FIGURES IN TEXT. PIG. PAGE i: Profile‘ot'a. Dam-according to: Dé-Sazilly,, €t0s..cnamalce ek agind mondguaee rein laden d wrk ed aca oeamMieeNe amas 7 2. Profile of a Dam illustrating GuiJlemain’s Method... 26.0.6... cee eect teen teneeee te n eens 7 3.. Profite of a, Dam illustrating Hétier’s: Method . 2. cs¢5 s0s ¢ees neces enegoneren gauss’ teas saeeedeeasaseeees 8 4. Diagram illustrating Clavenad’s Method..........6.0 cece eee n tree ete eet ene e nent en ene e eter tetneeeea 8 ‘5. cAtcherley’s: Models: of Dams. i i0is4 sacar erage nneaeee ab Ree E RT EGR U Shed Ramdand ha dsb mie laeaawaweae ead 9 6. Distribution of Pressure in a Masonry Wall.... 1.10.0... ccc eee eee sa Diahalea ete pageName eis ete y aes 13 47:. Distribution: of Pressure: ina: Masonry Wall. pa.c-cecens scares sas aaiea deen ad tats heuatanid kasd Suaee yea des 13 8.. Distubution of. Préssure:in, a. Masonry Wallicuincenccc ni anad sane rdaumiee ad adaluens beable dhe Shedd adda 13 9. Distribution of Pressure in a Masonry Wall... . 2.2... cc eens beeen erent tenn t eens 13 to. Distribution of Pressure in a Masonry Wall... . 1.2... ccc cee ene een tenn ee ne tenn teens 14 11. Distribution of Pressure in a Masonry Wall... . 0.1.6.6 e eet nett enter t nett enae 15 12. Distribution of Pressure in a Masonry Wall... 0.0.66. eee ete erent tenn e ene eee 15 13. Distribution of Pressure in a Masonry Wall... 0.0... c cece ee ee nn t tne tte ete eeeeee 16 14. Distribution of Pressure in a Masonry Wall...........+., eG CST SAO ASH COLAO RMT yesh Rea s aH 17 rs. Diagram-for Equations in Chapter Vlscuce.asccates cat ae ar taaaaneneaaden iced oooh b kaa sReaaENE TORE A 19 16. Diagram for Equations in Chapter III...........-.-.00 eee eee eee eee Lnpeee Ele Re METEOR KadadReS 20 17. Diagram for Equations in Chapter III......... 0.00 c eect ee eee nent tenet eee 22 18. Diagram for Equations in Chapter III......... 0... cece cence ee nnn tenner eens 22 19. Diagram for Equations in Chapter III. ....... 0.06 cece cece eee etn nee n een ence nnn nnees 23 ao. Diagram for Check: Caloulationsiss:.i40sivecescuada once eee v2 ors Ce ORMET DH Geyer EMneeORnaaes HERdeeEaE H 27 on, Trlangular Profile o.2.402s0 sensi cacao tes setaa hs eeadaes HERE PRMES SE EHS Salat EE bs dale eddie eae Mees 37 22, Sluice-gate. 2... cece EEE CETTE E EEE FEEDER EEE E ECan nena neon t tenes 5I 23. Sluice-gate Standard with Ball-bearings....... 0.6.6.0 eee e eee enn nee enn teens 51 24. Tapered Rollers for Sluice-gate Standard... 2.6... eee e eee ener ene teen eee 52 25. Sluice-gate Standard with Tapered Rollers......... 06.6.0 cece eee e eee eee een t nett es 52 26. Avignonet Dam. . ..... 6c ccc cece cee en en nnn eT R EEE EEE EEE EERE EER aE ees ase Eten nee ees 75 27. Sioule Dam. . 0... 0c Een Ene ED E EET t etn n tenet eee 75 28. Echapre Dam. ......... cece cece ne tenet tenet enn nnn ee rash gy sae Bh eabah Kaisa SMR N Ray SR IS ENTAdS 77 29. Cher Dam. 0... cece cece ee En eee EEE ee ene e enter eter teens 78 Bo. Urft Dam... oo. ccc ec en EEE e ee e ene ren renee nent tte e tees gr gr. Meer Allum Dam... 20... cee cece ete tr terete nent etter nen 124 32. Barossa Dam... ... 6c. cece ere en EE REET EEE ree nen tenet tees 126 33. La Grange Dam... 1.0... ieee eee cee nnn nn teeter nent neers 140 gq. Folsom Dam. ......- 06 eee etree tener nn nee ener eter t eer tent t enna 141 35. Maximum Section of New Croton Damseé nes cctccuctosu naga ceaty Sereagare ea oe eRe Oe ORS ERE Ge inmate 176 36. Gatehouse No. 1 of New Croton Dam. ............. FURS ae Kona A NASM oe yee AMdRaMancemiales Seea Se by 176 37. Gatehouse No. 2 Gt New Croton: Damas desc Pee akg ahs gerep-kangtnn ond Ei taaind dont Gee a a aah banead- a dusientnndh yee 177 38. Balanced Valve for New Croton Dam............ 00s sere eee re terete nee rene rennet ene 177 39. Cheesman Lake Dam...........-..--+- ea th a ao doi Me cheba ences sa’ hcl ate Neto aR RAS wean cha ha 198 go. Ithaca Dam. ... 16sec eect t etree etre teen ness (Viet. Gp mae RMR AAR 200 4t. Ithaca Dam... 12... c ces c eee eee enn ene nen NEE Ente eee etn etna teen ene e as aiewe OE 42. Concrete-steel Dam with Open Front. .......- +++. 0 0 sees seen erent terete tne e tere eens 211 43. Concrete-steel Curtain-dam. 2.0.06... 6. cece eee ee reer eset nents eet tenes 2i1 44. Concrete-steel Apron-dam. .. 2.1.0... eee cere ener nent e ett ees 212 4g. Concrete-steel Half-apron Damt..s....js01enso-ss eeene een sunarnese panna sastenmaeecapeeanesenenew eres 212 46. Proposed Concrete-steel Dam with Power-house. ....... 111+ +++ s ess eeee seen ener tet teen ene e es 213 47. Cross-section of Dam shown in Figs Aged eae ese s Geek eee eR TET PET hen owen addon aee eee snes eae Tes 213 48. Profile for Concrete-steel Dams. ... 0.0.20 sees eee ett r etree teeter nett tree eens 214 ag. Seluaplerwile Tatts; cssus vee dsasesss seer nese snes te ciae nd Shebi dnah stay Rene ReReR EMRE DEW TNeeF LAKES 219 a. Separating Welk: viver cade. rata vers Geena ye napets ee teaees speed enamine sneer es asad Steenahaeenehtes 227 51. Outlet from RESEEVOIES cs cau aiena eer isabewd sd A RGAE Gv oredaaatiames MPT ARSe LETS VOW Dee ome 230 5G, BER Dalton ofp svengan nae cinmes pedaunuews Gases Cons sadn i aes esp ANE s HARRY Rees eNeOeaes NANT 234 xi LIST OF FIGURES IN TEXT. FIG PAGE 53. San Leandro Dam...,.......c00e0eeeees deine voaiae eee abe fiber jae aceite saigiddoabinseapauaes eaaeeen sy 238 54. Pilareitos Dam................. ies eather. SS ee col alatevernnal & & wide Ghanntile gan airaaus,s 239 655 San, Andres Daitiic.inpaneeoes cake ceacties eeeeaeas y hibits oe $18 6618) DASOERERRA DO REA OF eusd ave neeeyaseess 239 50: ‘Vabeatid Dams... cscs sada ad does son bebe ew veSe wee eee Se euu eee shy ssiuasgeaes Kid hie Rae PRERAMRORS 240 57- Cross-section of La Mesa Dam....cecscercceecccsesetoscsereeereeneeeraees ei sae oh ideslaro atest tebienenhue. y's dich Spteue ss 251 6S ZUM Dams eas cesesnacancas stave Kp eeees Sa eam erie daw RR BOs bs ake MEE RECREUERALY Cd RARER KPO Ot Red eR 263 59. Tenango Dam... ...........05 5 ie Bs Shae auiscaaek wa oN ess uat oa h Naa e EO BRE RAR ReSidi cabasuadte eR RE OUR Ta Baie sae 264 Go; ‘Tenaheo Dati: sccqvadigas ooo toce dpi teth aes ese Gs GUE OE DN Rave Gaede Dy gear eRRn haadam nme tee ERE 264 61. Necaxa Dam No. 2..... fis b Godunst tach. duduMatabareih bh Psbia edad Mecoaue AOS 24S A GANAS NG Ee sian Ruane YS GRIN GAG tek ak. eee 265 62. Sketch of Reconstruction of Chatsworth Park Rock-fill Dam......... 00: e eee eee teen eee ene 273 63.. Pecos: Valley Dain No: as csccies scan ea suman re eo oind paeeoe Dewees SAminademoead Mada Tae aw Ries ee 274 643 Pecos Valley Dani Nowe aseae ck cece ea cuenase Ra dG deeb aN anes BERNE Gq AedWaAms dae sindleceens Tee MM 274 65; Castlewood, Dam: .:0csasusemmanteoiencdns chao eee cued weak Ss hanes WE araeake ANA Grs bate Gane A Bunlaine 276 66. Diagram of Timber Dam................00 0 cece eee eens LA cmPOee ehoatd MAME ENE de Gaia agi wae eee oiA 280 67; Dingram-OfF Timber Dattani sa gic aaa eg nWewa tate raudhbedbenme alanine Micimod ois Tee HAMM DA Cees OMe pw eergdets 280 68. Diagram of Timber Dam............... srigieay hy Bahete maaan MAR a Snare ane Rae Ea PieueReM eer KamEmeR Be TS VS 280 66: Log Dattnincads acca raw aghpinigiaa cing wines saaanmnias by ea ew sale HR gE DARI Dade eT MARAE meee ees 282 90s Cn b Gait, i tas oxcwma maaan ass co ertinn Qiteeloacs EY obo Guta recta Nn a ame a DeeieE DY Cog USERS MARE Oase 283 WT; PUEWAM: ys: doer cadher seer esses aoe death ethene Gd Saw S Meates MaweR NS tes HaGNE eRe Smee 284 wal, Plan =Car. g.9 be pained eehsvenate seid duaceat bua eRe ered ald Pau, elaua.a guanentuane whe Cae ARE TERESA OE 2a ee eee Nees 285 BD STON ATTA yuo bod iene ys Asus SN ERROR BO AMM i ORAM RIAL ade Asad LikeaNEi le dan asH Maa Tee aS PERE 285 Fao ram e: Tami ber aii 5. weve danse cans amma e Miia tam we haat Hee cits He Selgiod egg Maes waa GomnauenRNeS 286 75, Frame Timber Dai:. sscaaad gy cnca caw paenated 008 eae Pe aaieey ee eweg mpRTAT A PIU R_MNN Oe aes RES 287 76, Canyon Petty Dati: as caasr se esas Fades eating ex keuea POCRTERA ARONA eMER HIS seed atawwe Na sER eumiReE oe lee 293 ag, Pores: Nesdlé=daithy cvs cada teks s RSA TARO RE TEN AMER GOT e Se eI TRUM BYSRAMRwEeS Due ME Eee a TKN 303 Fos I INGEGIES TOR POI TM AMS ye Sane <.coas a duacanenistets a soa sbemavanSne Bim Sothguces Wess d Saauleratauw Sebnbandaed aodd aeaee MI aianens ere ae SMa EAE 304 7. Neéedlé with RUBE for POITée Das inaceinctacanariqaradead Leeward sarneagGKRs daditlemnale isha daltuues RaE Re 304, 80; Poirée Needle=damis si: sca cacweavamanacad cee sae DORA ATEE LOU TURES REG RARER 6 was ERAN ONE Hess 305 81. Be'gian Needle-dam...... Rhee aM EUSA ALetaR ousis MaMa UA sR eeRteER nastedan.s aaa ya dealekeie’s Sy kaya 308 $2, Boule Gate. cuiais cngedies sean ea ankawa i hee 064 P94 VRONTOE LETTE PE SNOAERN SE CERN AMER EES OMRS BeOS EEA ot 314 83... BOUIE Glare Moscow Danis: cia: ss amnaned tone Gcauiaoand Lemen ¥ tania de th Soe Bunge MG es aR eet broke Canes 315 Sa. (Camere Curtamedains IOvOnit Waew sucecscasie hesask ecudeh edge suaneneian doddas nd ub. Godedansel eld sdomes wb iu Roanareonp ead ayeures Subeiyseneeee Gusienud asus 316 85, Camere Curtainedam:, Side; Views «cos honda eeoes nileweihe Oteee dS AUWOOH TL EE ARONA PATE M amen ctaenee 317 86. Caméré Curtain-dam, Details. c.5scsicsaearaacssag a dammaaaana ge ogien sie ee a We seals Hag SES Abe E PRs we RIE ERAS 317 87. Caméré Curtain-dam,, (Crab, cn vs cniindee osge seas Heeger ewesns gnalendegs ena HENS DE eee dae Nes SE 318 88. Cameéré ‘Curtain-daii, (Crosssections «a veins tev aac ar inowac sel Rae batt aweed bhoes VESoes HORE eE MASE RAE wise BIO 80; Location Of Roses: Dai. irq. ia cot hee OR RA nee A Melduniseand rarer en Gkaddewed a oaind bd aWawe Mie Shae aise ava RAeE 320 go. Pier of Pcses Dam................ emibeh ie Geek Mean ents MN a aNNN aA ARR A fe each ate me A Raa Seatac EG sae ASC or ee aE 321 gt. Location of Sureshes: Daits.¢ 5 scicics waa tad eas smreincan a gnaty eae anneal aa de wae aeRae Ree a Saws eee P plu 322 o2. Thomas. Ariranie Dain, caajpcraaasa sie parenass SMa eve ema aetna nase SEES EUS LAST RaSS MEMES ROR 323 3). Thénatd ‘Shutter-danis oi 2ccgunsdgdapets.'s tigen 2 Gia Maewadededen ba eye eee R GES etene Eero a edward 327 oa: Chanoine Shuttersdam on. the Upper Seine: sc0cegcecedaysecaeatan cade rearons aguioa ne haga aelmen i nma ane 328 os. Chandirie Shutter-damt onthe Marne). i'..4..cimacaasacasse po senda qmnaieam due aa SA Qana ree eas Bema eaislaebads 328 96. Chanoine Shutter-dam of Port 4 L’Anglais Weir... . 10... 0. ec c eee bene cece eee eee enna eeeenneeaes 329 OY; Pasqueall Hutleri yas. ceictea manure oradacaaeecneai swe eee ay MPM ds. LeOREE MUAH TNI MOSES OYad A appa s 331 68. Section of Kanawha Dam is «siioviaecvovauy ptacige due ceveasdatunenes dees ad O58 Cre ee rere ree eee 333 Oo. Krantz’s. Pontoon Dat: os sndgamaataanesierea rOneie VED t ase bSes eee a aden a ies ewan anemacamaen 335 roo,, Krantz’s Pontoon Dativccs.acaneasds es eae eg ncitiiaard came’. e annmeda o ha.eaa yw aunmedue gh aed wm mae d Bama Ee oe 335 HOT: DB UChersly>. VALVEY 3 i. Borie 5 Sepduapinsaetindr ds Bade dayne Gu tsianeaed EUR Rah Sy avacaathnudte AY dra Bpetean Agen ole do a aaa Gao mNa aR ae 335 702; (Girard Shittendantis.a:.cwarkaawas die s08 aa ark maint % ee ea Gcemend hai dy ote aidinm Rep rabatet a wii aaa ma MIA G9 exc SR oS 336 fog: Desfontain es Drum-dam.n, uci cciaeata sia ccte ees 39s 4s stad asnyihania as eae naa MRAU RYN edw DeeE eH Adena Seudleis ans 338 ro4:. Abutment of Desfontaines, Drum-dam,.i.sicsacgacuerdsceas sa ioeaud PRa ek doa ce dee ew ea aue ee see ad Nama eee 339 165. Cuyinot Drim-dam,-: sere dameen seen cee eetenatel tanta soR ches y iia Ried des dp MOORE CARED SaOA rs 341 1HOO;, Chittend Gi DmGMsdaMty so gaueaus. a angaasvonaed dduscdiardcaus dedaacuataland id dre meee son hata ws, dvaeh igen “a tales aia yebicinela elanarnne Wlaeen eee 342 i07. Bear-trap iGate:, Davis: Island Dan: c+. oncoaaca vodonan cage wie Seangn Rigby ee pAOEEE SERGE MEda Laws 345 ro8: Bear-trap Damion: the Mame: ios cecreas piesa any ccias MRE RA ees FERS KDE ERRENR Ew bE boa aman eae s 346 100; DUBOIS: Gales tadasyeuas wsnidaag ye eacuen eamlons KEES eee TERIA Oem Sam Neue hah Adee sega derma sewed 347 MUO s WAT TONS Ate oi sisartec-a ae dase. 6 eas A RI it Sasa an an saan tae mg made amia ac Rude Sauna aed Mean naam nG Gila aalala emtenta ae cts 348 Spee: Gonmraaricl) 2G athe is aaica avy 0 8s we daca anaatignne csv Rat acdcn sept a Quake va ued eas BDA tart chien elma Ake rcets Seal eben in Gtk AT ARs Odes 348 Tha. Brinot Gales. poses kas a aansadone maven Renna nian emealengheiadentny Neowin chaeatadals sare a eeme sd Seats duimuaacedeeoden 348 sig. Brunot Gatey, :gosiaxyrereraeuseequarerinesannasenerspesny sos ae.s Luethes ho twed Henle wales eS aaa eae ae 348 114. Parker Gate... ...cscssss cere ence cesta taee nsec teeenes URGE RACES Fumie Neen POMARAE SEATS a Mmmge y qund ae 349 FIG, EIST OF TABLES. xiii PAGE r15. Lang Gate....... ...- LAR vED MUMS matNR Ne 4 eee ARSE A OA Hale eeu Goa congue d Gel ae RENE ee SN A eS 350 ELO. Marshall Gated. 6 cmd widisins vtqnisqae sy ot Mess Ween oaUGy ware ee sowas Sie ee Ra Decpakerereimaia ds 350 117. Joint-rod, for Stoney Gate of Beznau Dam, jfetann ees Sao e PACES MOINES Fh RRNA Rak oe SEEN Me ARG a2 118. Link-chains for Stoney Gate of Beznau Dam... ....... 6. cece cece cee cece eee ete tenet nnn nee eens 352 119. Diagram for Calculation of the Length of a Joint..... 0.0... cee cece cece eee e eee e nen e nen teen eee enee 404 120. Diagram for Calculation of the Length of a Joint... .. ccc eee e eee e eee e eee e een e eee e nen en eee e en ene eens 404 LIST OF TABLES. Table]. De Sazilly’s Profle-types¢ aacdais secs gaan cane oon aaAWOwEA pemUedea 4 Rade aga edamaad ied aacneaeds 388 ET. Delocte's: Bron €1y pein 2.h.is ase iaws Soa ccnarecmameeine BAgnaT te Ry aO a Reaais GRE ERENOREdeaee meNeTeA K 388 IIl..-Prof; Rankine’s. Profile-type: sicc-coccanionnvevad easy ini Sere eas tOEE HE SNS PEE Sees Madness eeeemLes 389 IV. Theoretical Profile on Prof. Rankine’s limits and conditions... . ....... ccc eee eee eee eee e ea ees 389 iV, Kran tz's: Pronlety pes sas cacguaaw nie tasemicnstomaraedadiadhite ieGs tae sceoe dara bone Dao ieedmimenan 390 VI, Prof, Harlacheér’s Profilety pes vice ccipicnogaicge: Qin duced pares bee aE ae Ma ee ME MERA AREER THe we 390 VII. ‘Crupnola’s: Profile-type..a. + snesesada asap et ea ganna te TOURS UT NODSOAS STTDTOTE easier etadagererne 391 VIIL.. Theorétical! Profle NOs: tia ccs sescnwiemi eee Wadia oa eels s Keaabine Pete HERMER EL PEST EEG 299 F Le TO ROES 301 IX. ie A” ONG 20 ei Gatand anid diate eee MQNeewed ta gaeataaaaaih aR saga paMRE TAS 392 X, ee 88 INGOs Sia ae aeabaanih gies eget eee mena reese s Deb aGuEEe eee eeee cana aadeuyasae 392 XI. #8 ES NG: Gig asoatiaeedn tienen ste adewed Tae A Man Sehr RETEST eaa Lome ddanens aes 393 XII. es Sie SING BS ia as gaia Srciwena 2 lem Andean uate Geren tema ee oat gramuneette eta NOS ait 303 XIII. s Of" ING, One kicanes anesad os Sedge ea GAs See eRe eee See Rees ae ee ree Esaga Te eae 304 XIV. Inclined Joints in Theoretical Profile No. 5.2.1.0... 000 e cece cece eee ete teen eee e nent e ee . 395 XV. Theoretical Profile No. 5 modified by Bouvier’s FOPMON Shs 5 ecassidalonaredauvewuens 8 iaG) Mes Sd aso Meeaunal Bavetreas 305 XVI. Theoretical Type No. Loo. cece cece eee tee een ee en enn e ene e ete nee e tence eee e tener n reas 396 XVIT. Practical Type No. 1...... cece eee eee eee ee een eee eet ene e ete eee e nen eterna ees 396 XVIII. Theoretical Type No. I].......cce ccc e eee e eee eet e eee e teen een ener e een tence rene tenner eee es 397 XIX. Practical Type No. 2.00... :e cee e ener nett eee ee eee eee teeter nner nee eee eee eS 307 XX. Practical Profile No. 1......-++-e eevee renseneyE aud Carttcaaa Redvaraibin Steak aad ae avecaty PRESTO OPE TEE Dee eee uMaales 398 XXI. ss (NGS Bie bx d Seims adic ganieagen ode swreei ean k ame TA Se DRM A athena Aes T Mae eae ia 398 XXII. oe ONO. Bocce cece ener t ee ener ence ee enn ee een eee nena ress tenes eater nett e te tiens 309 XXIII. Data of Masonry Dams... 0... eee e cree cece eect eee tet e nen e ene e een cent e ete t et en eee ea eee e net aes 400 XXIV. High Earth Dams... 0.6.6. sce e eee e ee r eee e een teen enter teen enn e tener e tenses 401 XXV. Equivalents of the Metric Measures, according to the U. S. Standard. ..--sseseesereereeeeereeeeeeenees qo2 DESIGN AND CONSTRUCTION OF Masonry Dams. CHAPTER I. INTRODUCTION. THE remains of ancient works still existing in India and Ceylon bear evidence that the construction of reservoirs for storing water dates from a very remote period of his- tory. The ordinary manner of forming these basins, some of which were of vast extent, consisted in closing a valley by dams of earth; and it was not until comparatively recent times that walls of masonry were employed for such purposes. This method of con. struction seems to have been first adopted in the southern part of Spain, where, about the sixteenth century, large reservoirs for irrigation were constructed. Much as these early masonry dams excite our admiration by their great dimensions and massiveness, their pro- portions demonstrate that their designers had no correct conception of the forces to be resisted. By a faulty distribution the great mass of material in some of these walls pro- duces undue strains in the masonry or on the foundation, becoming thus a source of weakness rather than of strength. Prior to the middle of the present century most ma- sonry dams were built according to defective plans. It has been shown, indeed, that some of these walls would have been stronger had their positions been reversed, the down-stream face being turned up-stream. The French engineers advanced the first rational theory of masonry dams, and proved its correctness by applying it in the construction of some of the highest and boldest reservoir walls of the present time. By means of the great storage basins thus obtained, they control the flow of rivers, retaining the excess of water during the period of flood for the time of drought. The havoc due to inundations may thus be largely prevented, and replaced by all the benefits resulting from irrigation, domestic water supply, and the furnishing of a cheap motive power. Before entering upon any mathematical details, we will glance briefly at the differ ent steps that have been made in the development of the theory of masonry dams. The first writer who investigated this subject in a satis- factory manner was M. de Sazilly. His memoir on the design of reservoir walls ap- peared in the “Annales des Ponts et Chaussées” for 1853. According to this writer the safety of a masonry dam depends upon the compliance with the following two condi- De Sazilly. tions: ist. The pressures sustained by the masonry or its foundation must never exceed a certain safe limit. 2d. There must be no possibility of any portion of the masonry sliding on that below, or of the whole wall moving on the foundation. 2 DESIGN AND CONSTRUCTION OF MASONRY DAMS. To devise a formula containing both of the above conditions of safety would be diffi- cult, if not, indeed, impossible. However, M. de Sazilly states that no masonry dam has been known to fail by sliding, and he therefore recommends that the profile of a dam be designed solely with reference to the first of the conditions, leaving it to a subsequent trial to determine whether the second has been fulfilled. This will generally be found to be the case, especially if the assumed limit of pressure is not very high and the dam has a con- siderable top-width. Should we find that the wall or part of it might slide, then Sazilly’s. method would be to increase the thickness of the profile by recalculating it for a lower limit of pressure. This writer pointed out that, in determining the maxima pressures. in the masonry or on its foundation, two extreme cases must be considered: Ist. When the reservoir is full. 2d. When the reservoir is empty. These two conditions give the extreme positions of the lines of pressure* in a dam, the first causing the maximum pressure in any horizontal plane to be at the front (down-. stream) face of the wall, and the second producing them at the back (up-stream) face. The practical considerations of economy require that a dam should contain the minimum amount of material consistent with safety. Having established a fixed limit of pressure, Sazilly’s ideal profile is that in which the maxima pressures in both faces just reach the limit. He called this “the profile of equal resistance.” In attempting to find formule for determining its form, Sazilly experienced no difficulty in obtaining the correct differ- ential equations, but found it impossible to integrate them, and had therefore to abandon the idea of finding the proper curves for the faces of the “profile of equal resistance.” The difficulties of the integration may, however, be avoided by substituting for curved. outlines polygonal or stepped faces. In either case we must assume the dam, for the purposes of calculation, to be divided into courses by horizontal planes. The smaller the depth of these courses, the closer the “profile of equal resistance” will be approached, the approximate types involving always a slight excess of masonry. Against polygonal faces Sazilly urges the following objec- tions: 1st. The angles form points of weakness. 2d. The gentle slopes of the faces favor vegetation of parasitical plants, which injure: the masonry. 3d. Such a wall would have a bad appearance and would be difficult to execute. For the above reasons he recommends as the best practical type a stepped profile, such as shown in Plate I and Table I, for which he gives. formule. The next engineer who advanced a method for determining the profile of a masonry Buen: dam was M. Delocre. The frequent inundations in the valley of the Loire led the French engineers to plan large reservoirs for retaining the flood- water. Good locations for such works were readily to be found in the upper valleys of the branches of this river, but sufficient storage capacity could only be obtained by con- structing dams up to 50 metres (164 ft.) in height. To have formed them of earth would * The line of pressure (called also line of resistance) is a line intersecting each joint of a structure (whether jt be real or imaginary) at the point of application of the resultant of all the forces acting on that joint. INTRODUCTION. 3 have been extremely hazardous, and walls of masonry were therefore decided upon. M. de Greff, the Chief Engineer of the “ Département” in which these reservoirs were to be located, assigned the study of the best type of profile to M. Delocre, and it is upon this engineer’s investigations and formule that most of the high dams built within recent times have been based. Starting with the same conditions and fundamental formule as Sazilly, Delocre arrived at different conclusions. He demonstrated that a stepped profile involved considerable waste of material and required, moreover, an expensive class of masonry for the steps. He argued that the objections raised by Sazilly against polygo- nal faces would lose their force if only a few changes of slope were employed, and that by adopting such outlines a considerable economy might be effected. Plate II. and Table II. give the type of profile recommended by Delocre. For sake of comparison he made calculations for two profiles of a dam 50 metres high, one according to Sazilly’s method, and the other according to his own, basing them upon a weight of masonry of 125 lbs. per cubic foot, and on a limiting pressure of 6 kilos. per square centimetre (6.15 tons of 2000 Ibs. per sq. foot) In Sazilly’s type this pressure is only reached at the re-entrant angles of the steps; in Delocre’s, only at the vertices of the angles in the faces. The calculations are made for one lineal metre of wall, which is supposed to resist the thrust of the water simply by its weight. Tables I. and II. show that these profiles differ very little from each other as regards stability or resistance to sliding, but the following figures prove that an economy results from adopting Delocre’s type: Exposed surface for Area of profile, one lineal metre of wall, in square metres, in square metres, panlly's tyPGs « & 4 ew S 4 we ee @ WRB ee 152.15 Delocres type, « «. » « ¥ & & = © & « + GORZO 119.70 33-45 32.45 Delocre has given lengthy formule for calculating profiles according to his method, and also investigated the additional strength which might be obtained by building a dam on a horizontal curve in plan. The results of his studies were known in 1858, and formed the basis of the design for the Furens dam near St. Etienne, a reservoir wall 50 metres in height. It was not, however, until after the completion of this work that M. Delocre published in the “Annales des Ponts et Chaussées” for 1866 a memoir giving the details of his researches. To trace the history of our subject chronologically, we must now turn to an English writer for the next marked advance. In connection with some Bais ec a ankine. proposed reservoirs for the city of Bombay, the question arose of deciding between the respective merits of earthen and masonry dams. In order to obtain the opin- ion of a high scientific authority on this subject the question was submitted to Prof. W. J. M. Rankine, who was also requested to make a rigid mathematical investigation of the best form of profile for a masonry dam. The report* written by Prof. Rankine in response to this request is very complete. His views of the considerations that ought to determine the design for such a dam will readily be accepted. While Rankine recommends that the profile should be determined mainly by the principles * See Prof. Rankine’s ‘‘ Miscellaneous Scientific Papers,” 1887. 4 DESIGN AND CONSTRUCTION OF MASONRY DAMS. laid down by the French engineers, he improves their methods in some respects. Thus these engineers, in calculating the maxima pressures in the masonry, had only considered the vertical component of the resultant pressure of the forces acting at any joint. They therefore assumed the same limit for the intensity of vertical pressure at both faces of the wall. Prof. Rankine says, however: “It appears to me that there are the following reasons for adopting a lower limit at the outer than at the inner face. The direction in which the pressure is exerted amongst the particles close to either face of the masonry is necessarily that of a tangent to that face; and, unless the face is vertical, the pressure found by means of the ordinary formule is not the whole pressure, but only its vertical component; and the whole pressure exceeds the vertical pressure in a ratio which becomes the greater, the greater the ‘batter,’ or deviation of the face from the vertical The outer face of the wall has a much greater batter than the inner face; therefore, in order that the masonry of the outer face may not be more severely strained when the reservoir is full than that of the inner face when the reservoir is empty, a lower limit must be taken for the intensity of the vertical pressure at the outer face than at the inner face... .” This eminent writer did not attempt to determine the ratio which the limits of the vertical pressure at the front and back face ought to bear to each other, by any mathematical deduction, as he deemed the data upon which it would have to be based too uncertain. In choosing the limits of pressure for the profile accompanying his report (see Plate III. and Table III.) he was guided entirely by what experience had proved to be safe, and adopted: Limit of vertical pressure, in pounds per square foot. For front (down-stream) face, . 2. » © © © © «© © « © 15,625 For back (up-stream) face, . . . 6 © © © »© «© «© « + 20,000 The same reasoning which led Rankine to recommend a lower limit of vertical pressure for the front face than for the back face induced him to make the pressures at the front face diminish as the batter increases. Here, too, he followed practical examples, as he thought it impossible in our present state of knowledge to deduce a law for this diminution. He designed his profile therefore in such manner that the maximum pressure at a depth of 150 feet would equal the pressure at the same depth in the Furens dam; viz., 64 kilos. per square centimetre, or about 6.65 tons of 2000 Ibs. per square foot. Below this depth the maxima pressures diminish gradually. Another principle pointed out by Prof. Rankine is that no tension must be allowed in the masonry. Theoretically this would occur (as will be shown in Chapter II.) whenever the line of pressure lies at any point outside of the centre third of the profile. The stability of the dam against overturning depends upon the position of the line of pressure. For the above reasons Rankine limits these lines (reservoir full or empty) to the centre third of the profile. The conditions given by Rankine do not prescribe any definite form of profile, but when we add the consideration of economy, requiring the minimum amount of inateria] consistent with safety, the choice of form becomes very limited. The types of Sazilly and Delocre involve very lengthy calculations. Prof. Rankine endeavored to find simpler INTRODUCTION. 5 formula. One of the effects of his using a higher limit of pressure for the back face than for the front is to reduce the batter of the former considerably from that of the French types. The vertical component of the water-pressure on the back of dam can therefore add but little to the stability of the wall. Prof. Rankine neglected chis com- ponent in his formule, as the slight error thus introduced would be in the direction of safety, and also simplifies largely the mathematical investigation. As regards the profile (Plate III.) accompanying his report, he says: “In choosing a form in order to fulfil the conditions without any practical important excess in the expenditure of material beyond what is necessary, I have been guided by the considera- tion that a form whose dimensions, sectional area, and centre of gravity under different circumstances are found by short and simple calculations, is to be preferred to one of a more complex kind when their merits in other respects are equal, and I have chosen logarithmic curves for both the inner and outer face, the common subtangent being 80 feet for both.” The formule given by Prof. Rankine for determining the thickness, area, etc., of this profile are certainly extremely simple; but then they produce only this one profile, whose dimensions might as well be calculated once for all. Change the data upon which it is based, such as the weight of masonry, limiting pressures, etc., and the simplicity of this method disappears. Rankine states that his general formule which we would have to employ in snch a case are “incapable of solution by any direct process.” They can, however, be solved approximately by a process of trial and error, involving the higher mathematics. If by means of logarithmic curves a profile differing but little from the exact theoretical type could be obtained, there would be no objections to the use of such approximate methods. Sazilly had demonstrated that. a wall sustaining only its own weight would contain the minimum amount of material, consistent with a fixed limit of pressure, by having symmetrical faces, which would be vertical until the limit of pressure were reached, and would then follow logarithmic curves. But similar outlines will not give the best profile for a dam resisting water-pressure, as will be shown in Chapter IV. In 1856 M. Le Blanc demonstrated, in a study of the stability of arches, that the action of an inclined force R on a joint did not only produce a compression due to its normal component R cos a—a being the angle made by RK with a vertical line—but that, on the contrary, 5 ‘ : R the force to be considered as producing the compression was me The arguments advanced by M. Le Blanc to prove his views did not attract much attention, at the time, and were repeated by him in 1869, but it was not until 1874 that M. Bouvier applied the principles advocated by M. Le Blanc in making calculations of the pressures that would occur in the Ternay Dam, France, if the high-water level of the reservoir were raised 1.65 metres. Up to that time all writers on the subject of masonry dams, with the exception of Rankine, had calculated the rhaxima pressures in the masonry by considering only the distribution of the vertical component of the resultant pressure on a horizontal joint. * M. Bellet’s article on masonry dams in La Houille Blanche for July 1905. 6 DESIGN AND CONSTRUCTION OF MASONRY DAMS. Rankine, as stated on page 4, made some allowance for the pressures produced by the inclined resultant in the case of reservoir full by adopting a lower limit of safe vertical pressure for the down-stream than for the up-stream face of the dam. M. Bouvier * proposed to calculate the pressures of the whole resultant pressure at any joint by considering the joint to be projected at right angles to the line of action of the resultant. The details of his method will be explained in the following chapter. The maxima pressures found by Bouvier’s formule are always greater than those obtained by the older methods, and, if the same limits of pressure be adopted, a profile found by the older methods must be increased in width to satisfy the formule of Bouvier. Another analytical method of calculating the profile of a masonry dam was advanced by M. Pelletreau in the “Annales des Ponts et Chaussées” for 1876, 1877, and 1879. This writer adopted the same basis as Sazilly and Delocre, placing no limits to the posi- tions of the lines of pressure. By an intricate investigation involving the higher mathe- matics he found a simple series which expresses the thickness of a dam at any depth, so long as the back face remains vertical; but for the case when both faces must be battered he did not succeed in finding a general formula. A later memoir by Pelletreau on the subject of masonry dams is published in the “Annales des Ponts et Chaussées” for 1897. M de Beauve has given in his ‘“‘Manuel de L’Ingénieur des Ponts et Chaussées” a graphic method of finding the profile of a dam, based upon Sazilly’s and Delocre’s condi- tions, which is accurate but laborious. Empirical formule for determining the profile of a masonry dam have been devised by Molesworth (see his Pocket-book of Engineering Formule) and by others. A method consisting partly of equations and partly of trial calculations is given by W. B. Coventry in his memoir on “The Design and Stability of Masonry Dams” in Proceedings of the Institute of Civil Engineers (1885-86). Prof. A. R. Harlacher of Prague, in a report on a proposed dam near Komatau (Bohemia), written in 1875, recommends trial calculations as the best practical method of finding the correct profile for a masonry dam. In this manner he designed the profile given in Plate VI and Table VI. M. Krantz t and M. Crugnolat have published profile types for dams of various heights which were probably found by trial. Neither of these engineers gives any formule for this purpose. The types they proposed for a dam 50 metres (164 feet) high are shown, respectively, in Plate V and Table V, and in Plate VII and Table VII. Prof. Franz Kreuter has given some formule for calculating the profile of a masonry dam in the Proceedings of the Institute of Civil Engineers for 1893-94. While they make the profile sufficiently strong, they do not produce the section of minimum area, satisfying the given conditions. M. Guillemain advocated, in his work “Rivitres et Canaux” in “L’Encyclopédie des eens Travaux publics” a new method of determining profiles of masonry dams, based upon the consideration of oblique joints. His method is as follows: Let Fig. 1 represent a profile determined by the methods of Sazilly, Delocre, or Ran- kine. If, instead of calculating the distribution of the vertical component of the resultant * Bouvier’s Memoir in the ‘‘Annales des Ponts et Chaussees” for 1875. + Etude sur les murs de réservoir. Paris, 1870. ¢{ Muri di Sostegno e Traverse dei Serbatoi d’Acqua. Torino, 1882. INTRODUCTION. 7 of the water pressure to the depth N and of the weight of the masonry upon the hezzzontal joint NM, we find the distribution of pressure on the inclined joint MS, taking into consid- eration the full depth of the water to S, we shall find a greater pressure at M. This pressure may even exceed the pressure at the down-stream toe T. If the pressure found at M, by considering the inclined joint SM, be greater than the adopted limit of safety, the profile must be increased in width at this point sufficiently to keep the maximum pressure on the joint within the fixed limit. Guillemain’s method consists in calculating pressures on inclined joints radiating from a point O (Fig. 2) at the front face of the dam and increasing the width of the profile so as to keep the maximum pressure found in this manner within the adopted limits of safety. The profile based upon this condition is to be found by trial. M. Hétier, in a study of retaining-walls, including masonry dams,* comes to the same conclusion as Guillemain, that a dam should have a greater section toward its base than that given by the method of Sazilly, Delocre, etc. Taking in Fig. 3 the down-stream aie face as being given bya straight line from M to the base, Hétier investigates different inclined joints revolving about a point Cn on the up-stream_face, and finds expressions for the maximum and minimum pressures produced at the down-stream side. If the maximum pressure exceeds the adopted limit the width of the profile must be increased. The profile resulting from this method is somewhat like the profile found by Guillemain. M. Clavenad, who was the secretary of the Commission appointed to investigate the causes of the failure of the Habra Dam in Algiers, q.v., came to the conclusion that the failure was due to shearing in an inclined direction.t Guillemain and Siees: Hétier advocated making calculations for inclined joints in a dam. Clavenad recommended that the resistance of the dam to shearing be also calculated for inclined joints. This method is as follows: In Fig. 4 let MA represent in magnitude and direction the resultant force applied to a dam ABCD and let AN represent the weight of the triangle ABE, AE being any *M. Hétier s memoir im ‘‘Annales des Fonts et Chaussées”’ for 1885, TM. eee ee in ‘‘Annales des Ponts et Chaussées’’ for 1887, aL 8 DESIGN AND CONSTRUCTION OF MASONRY DAMS. assumed inclined joint. Draw NP perpendicular to AE, and MP parallel to AZ. The length NP will represent the normal component of the pressures on AE, and MP will represent the tangential component. If from the point N we draw the line NK, making with the normal line NP the angle of friction for masonry on masonry, which we will denote by f, the length AP will Fic. 4. represent the resistance to sliding, due solely to friction, and MK will represent the shearing strain to which the masonry is exposed. This should be ascertained for different inclinations of joints radiating from A. If the greatest shear found in this manner should exceed the resistance masonry can safely oppose to shearing the dam would evidently fail by shearing and should be given a large profile. The most recent and best French method of determining the profile of a masonry dam is due to M. Maurice Levy. We cannot give this method in detail here and must refer the reader to Levy’s Memoirs in “L’Acadamie des Sciences,” August 5, 1895, and in the “Annales des Ponts et Chaussées” for 1897. In a paper on “Some Disregarded Points in the Stability of Masonry Dams,” * L. W. Ricker: Atcherley, Demonstrator of Applied Mechanics, University College, London, who received some assistance in this matter from Prof. Karl Pearson, F.R.S., University College, London, points out some defects in the accepted methods of designing the profiles of masonry dams. He states: “We see no reason whatever why dams should be tested solely by taking horizontal cross-sections, and asserting that the line of resistance must lie in the horizontal middle third, and absolutely neglecting the stresses across the vertical sections of the tail. We consider that if the former condition is valid, then no dam ought to be passed unless it can be shown that there is no tension of any serious value across the vertical cross-sections of the tail. We believe that a great number of dams, as now designed, will be found to have very substantial tension in the tail, and this is, in our opinion, a source of weakness in dam construction which has not been properly considered and allowed for.” By “tail” in the above Atcherlcy refers to that part of the dam which is generally Se * Published in ‘‘Draper’s Company Research Memoirs,’’ Techn ' Series II, London, 1904, INTRODUCTION. 9 designated by American engineers as the “down-stream toe.” Bouvier, Guillemain, etc., recommended that the strength of a dam be not only tested for horizontal joints but also for inclined joints. Atcherley goes one step farther and advises that vertical joints be also assumed and tested. As a result of his studies and of experiments made with models of dams (Fig. 5) he reached the conclusion that a dam will be found to be weaker, if tested for vertical joints, instead of horizontal joints, and that large tensions will be found to exist across the vertical sections. Atcherley tested his conclusions by experiments made with two wooden models of dams, one being divided into horizontal strata and the other into vertical strata (Fig. 5). Fic. s—ATCHERLEY’s Mopets oF Dams. The pull representing the water pressure was produced by a cord which passed over a vertical pulley and terminated in a bucket into which shot was gradually dropped. In the case of the model divided into horizontal strata, the pull of the cord was communicated to a stiff lath, which bore on the ends of the horizontal strata through two longitudinal strips of India-rubber tubing. The angle of friction for the wooden strips, which had been left almost rough sawn to increase the friction, varied from about 25 to 30 degrees, while for masonry on masonry this angle is usually assumed at 30-36 degrees. Different expedients were resorted to to increase the friction between the strips of wood. As regards the main features of the numerous experiments made, Atcherley states: “The horizontally stratified dam either sheared at its base or just above the tail between the third and fourth strata; in either case the giving way at one or other of these sections was the signal for an approaching general collapse. The vertically stratified 10 DESIGN AND CONSTRUCTION OF MASONRY DAMS. dam opened up by tension very close to the tail and then sheared over. It had to be watched very closely to follow the sequence of events, as the collapse was far more immediate and sudden than in the case of the horizontally stratified dam. The nature of the rupture could be better exhibited by pasting the last two or three blocks together with tissue paper and then the dam invariably opened up by tension at the next section and showed this opening up in a marked manner.” The conclusions drawn by Atcherley from these experiments are: “r. The current idea that the critical sections of a dam are the horizontal sections is entirely erroneous. A dam collapses first by the tension on the vertical sections of the toe. ‘““o, The shearing of the vertical sections over each other follows immediately on this opening up by tension. ‘**2. It is probable that the shear on the horizontal sections is also a far more important matter than is usually supposed. ‘. “Tt follows from this that getting the line of resistance into ‘the middle third of the horizontal sections, upon which all energy seems at present to be concentrated, is by na means the hardest and stiffest part of dam design. We should be much surprised if, with all the labor spent on this point, the bulk of existing dam constructions are not for masonry under very considerable tension, i.e., a tension across the vertical sections, which has been hitherto disregarded. “We propose therefore to lay it down as a rule for the construction of future dams that the stability of the dam from the standpoint of the vertical sections must be con- sidered in the first place. If this be satisfactory, we believe that the horizontal sections will be found to be stable, but of course the latter must be independently investigated.” In the preceding pages we have traced the development of the theory upon which the profile of a masonry dam should be based. The principles upon which the stability of a masonry dam is usually considered to depend are very simple, but the mathematics to which they give rise, when applied to the design of a profile, are exceedingly complicated. The formule devised for this purpose are so unsatisfactory that some engineers prefer to find a proper profile for a dam by means of trial calculations. While a correct profile for a masonry dam may doubtless be found by a sufficient number of trials, such a method is very laborious and unsatisfactory. Impossible as it may be to determine at once the proper outlines for a profile which shall contain the minimum area consistent with the given conditions, there are no great mathematical difficulties involved in calculating its thickness at intervals, commencing at the top. To obtain the minimum area these intervals should be infinitely small. For practical pur- poses we can find a profile which shall approach the true theoretical type as closely as may be desired, by making the intervals at which the calculations are made sufficiently small. The profile resulting from this method will have polygonal outlines, involving many changes of slope. As it fulfils all the given conditions and contains, at the same time, practically the minimum area consistent therewith, we shall call it ¢he Theoretical Profile. \t might serve as a design for a dam, were it not for constructive objections to the many changes of batter in the faces. To obtain a profile which can be readily INTRODUCTION. 11 executed and also offers a pleasing effect, we have only to fit a few simple curves or straight lines to the theoretical form, reaching thus a Practical Profile. Small changes made for this purpose will have but a trifling effect upon the stability of the dam; and while the practical profile may not satisfy the given conditions rigidly, it will cer- tainly do so practically. The methods proposed by the eminent engineers already mentioned give but approximations to the correct theoretical form. Closer results may be obtained by following the method we have just explained. The equations we shall give for this purpose are exceedingly simple, being all quadratic with the exception of one of the third degree, which will seldom be used. The profile for the proposed Quaker Bridge Dam (see Plate LXXVIII.) was determined in this manner. Before explaining our method in full, we will first examine in the next chapter the fundamental formule used by all writers for determining the distribution of stress in a wall of masonry. 12 DESIGN AND CONSTRUCTION OF MASONRY DAMS. CHAPTER II. DISTRIBUTION OF PRESSURE IN A WALL OF MASONRY. SCIENCE has not yet revealed the laws which the internal stresses in a mass of masonry follow. We are therefore obliged, in treating of masonry dams, to resort to some safe hypothesis which shall furnish results approximately correct. All mathematical formula for masonry dams have thus far been established by considering these walls as rigid and composed of homogeneous masonry. This hypothesis involves two inaccuracies, as masonry is always more or less elastic, and seldom perfectly homogeneous. We shall show in this chapter that by assuming a dam to be rigid we exaggerate, in all probability, the pressures in the weakest part of the wall, namely, near the faces,—and make thus an error in the direction of safety. By careful inspection during construction we may ob- tain masonry which shall be practically homogeneous. The above hypothesis may there- fore be safely accepted, and we shall in future consider masonry dams as forming rigid homogeneous monoliths. Another assumption which is generally made is that a dam will resist the thrust of the water simply by its own weight. It follows from this that in studying the con- ditions of equilibrium of such a wall (every part of which is supposed to be built accord- ing to the same profile) we need only consider a section one foot long. For the present investigations we will assume a dam built according to some ordinary type, having sloping faces and a rectangular base, resting on a horizontal foundation. Whether the reservoir be empty, partially or totally filled, the given section of wall will be acted upon by symmetrical forces. Their resultant must lie in a vertical plane, per- pendicular to the faces of the wall, and bisecting the given section. When the reservoir is empty the resultant will be the total weight of the wall acting vertically through its centre of gravity. We will confine ourselves first to this case and investigate the laws of distribution of the pressure on the base of the wall. Let us suppose the dam to be rigid and built upon a perfectly elastic foundation. When the resultant pressure passes through the centre of gravity of the base (which in the given case is also its geometrical centre) the pressure will be uniformly dis- tributed over the foundation, by compressing which the dam will settle evenly, its base remaining horizontal. When, however, the resultant pressure does not pass through the centre of gravity of the base, it will no longer be uniformly distributed on the founda- tion. The eccentric resultant by throwing more pressure on one edge of the base than on the other will cause unequal settling and therefore tilt the dam. Owing to the rigidity of the wall and the elasticity of the foundation, the pressures on the latter will now follow the laws of a uniformly varying stress, and may be represented by the ordi- nates between a horizontal and an inclined line. ; The reaction of the foundation from face to face of wall may be shown graphically by a plane figure, whose area will represent the total pressure, whose centre of gravity will lie DISTRIBUTION OF PRESSURE IN A WALL OF MASONRY. 13 in the line of action of the resultant pressure, and whose vertical ordinate at any point will give the corresponding intensity of stress. A uniformly distributed pressure would be represented graphically by a rectangle as in Fig. 6. A uniformly varying pressure will be shown graphically by a trapezoid or triangle, depending upon the position of the result- Fic. 6. Fic. 7. He ant pressure, which must pass through the centre of gravity of the figure, viz: When the eccentricity of the resultant is less than one sixth the width of the base, the reaction of the foundation will be shown by a trapezoid, Fig. 7. Should this eccentricity just equal one sixth the width of the base, the trapezoid would become a triangle, Fig. 8. When the resultant is still nearer to one edge, the dam will be tilted so much that part of the base Fic. g. will have to bear the whole pressure, the remaining portion being raised entirely from the ground. The ‘reaction in this case will also be represented by a triangle as in Fig. 9. Should the afihesion between the foundation and the base prevent the latter from being partially raised from, the ground, then part of the base will have to sustain tension. This will modify the distribution of the pressure, which, however, will still form a uni- a CW I4 DESIGN AND CONSTRUCTION OF MASONRY DAMS. formly varying stress. To illustrate the above laws, imagine a rigid plank floating in water and bearing a movable load. As this latter is shifted from the centre towards either end, each of the above cases will arise, the water-pressure under the plank representing the reaction of the foundation. We have thus far considered the foundation as elastic, but will now suppose it to be rigid. It can no longer be compressed by the weight of the dam; but as the ten- dency to cause compression remains the same whether the foundation be rigid or elas- tic, it is rational to assume the same distribution of pressure for both cases. The laws of distribution of pressure, given above, were first indicated by M. Meéry in his memoir on the stability of arches, and were perfected by M. Bélanger in the course of Applied Mechanics taught by him at the Ecole des Ponts et Chaussées.* The formule resulting from these laws may be derived eaecid in many different ways. The following w solution will be found to give the usual formule by a short method. Both the dam and the foundation are assumed as rigid. a Uw b b Let W =the total pressure on the base ad; p u == the distance of W from the nearer : P edge 0; e p =the maximum intensity of pres- 1 ¥g sure on the foundation; d 3 7 e p’ =the minimum intensity of pressure on the foundation; Z =the width of the base ad; g =the centre of gravity of triangle ced. First let a > _ e Trapezoid ace = the reaction of the foundation : = abcd — ecd z =pl— > P’). As W and the reaction of the foundation are in equilibrium, the algebraic sum of their moments about any point must be zero. Taking moments about the point g, we find, since the moment of thé’triangle cde is o, fw Gnr)=0 whence p=? FO~H), i. ewe we we wy we we GY Z : ; When 4 = 3" the trapezoid of reaction becomes a triangle, and we have: a *M., Sazilly’s memoir on reservoir walls in the ‘‘ Annales des Ponts et Chaus. ces for 1853, DISTRIBUTION OF PRESSURE IN A WALL OF MASONRY. aS Z : ‘ When uw < 3 we should have, according to the laws of a uniformly varying stress, a posi- tive and a negative triangle, the former representing the pressure on the foundation, the latter the tension on the base. As Fic, 11, it would, however, be unsafe to de- Ww pend upon the tension in the masonry, it is best to neglect it in calculating the pressure on the foundation. Fig. °% shows this case. Neglecting the tension ade, and tak- ing moments about J, we obtain Wu — SPU, ty fi 2 @ hence p=” aw Formule A, B and C are correct for a rigid dam resting upon a rigid or elastic foundation. But now let us suppose the masonry itself to be elastic. We have no exact knowledge of the manner in which pressures would be distributed in such a body. How- ever, in the practical cases with which we have to deal we can indicate how the formule A, B and C would have to be modified. Unless the height of a dam be very insignifi- cant, one or both faces will be sloped or stepped. The compression of the masonry at the base of a dam, resulting from its own weight, will depend mainly upon the column -of masonry directly over any given part. The central portions of the base will, there- fore, be compressed more than those near the edges, and consequently the diagrams of the reaction of the foundation will be modified somewhat — as shown in Fig. 12 by the curved line. The pressures near the edges of the base will be less and in the other parts IR greater than those calculated for a rigid dam. We certainly cannot conceive of the opposite to this taking place. Now, the central portions of the masonry, owing to the lateral support they receive, can bear safely much greater pressures than the masonry at the faces. Thus, we conclude that the inaccuracies involved in using formule A, B and C will be -on the safe side. These formule may evidently be applied in finding the pressures in the masonry at any given plane; for we may consider the part of the wall above the plane as forming the dam proper, and the lower part as the foundation. Thus far we have only considered the distribution of a vertical resultant on a horizontal plane. When, however, the resultant is inclined (as will always be the case when the reservoir is filled) it can be resolved into two components, one parallel with and the other normal to the civen plane. The former will be opposed by the resistance of the dam to sliding or sheazinz. The latter will be distributed in accordance with formule A, B or C. This metaod of Soteee the pressures in the masonry at any horizontal joint has 16 DESIGN AND CONSTRUCTION OF MASONRY DAMS. been adopted by most of the early writers on the subject of dams. But, although the results obtained are correct as regards the distribution of the normal pressure, this method does not determine the maxima pressures to which the masonry is subjected. As already stated in Chapter I., Prof. Rankine argues that the pressures near the faces of the wall will be tangential to them, and that therefore, in considering the pressures normal to a given horizontal joint, we have only taken part and not the whole pressure. Fic. 13. As he thought it impossible to find the real R maxima pressures by any theoretical means, he advised the use of the old method of resolving the resultant pressure into a normal and parallel component; but adopted different limits of pres- sure for the front and back face of the wall, on account of the difference in their batters. The French engineer M. Bouvier claimed a that the maxima pressures would depend upon the inclination of the resultant, and therefore modified the formule already given as follows:* Let &R =the resultant pressure on an imaginary joint #2; a =the angle of inclination of R from a vertical line; Z=length of joint 227; “= length of joint mx’, which is perpendicular to the direction of R; “= mo; u' = mo’. M. Bouvier considers the pressure of R to be distributed in the following manner on the joint sz’ to which it is normal: He neglects the weight of triangle mn”, and considers it simply as transmitting the pressure of R to mx'’, He also assumes that no pressure will pass through the triangle 77'7’’. The whole pressure of A will, there- fore, be distributed on mz’ in accordance with the laws embodied in formule A, B and C. We must, however,: substitute forZ . ... . 2cosa=mn"; for mw; . . . . . “#COSa; for We. 8 « w a RR The resulting formule will be: pa wv’ EPL COSY OO Se SE RIS ton 2%. , Pa! BP ca Bat a a vee a, BI / ce 2 7 v= ee Ew Re ee ew, Cc The pressures obtained by formule A’, B’ and C’ are evidently always in excess of those derived by A, Band C. M. Bouvier states that M. Blanc arrived ‘at the ame * *Calculs de résistance des grands barrages en maconnerie.” Annales des Ponts et Chausseés, Avg. 1875, Big DISTRIBUTION OF PRESSURE IN A WALL OF MASONRY. 17 conclusions from a more general discussion of the subject (see memoir No. 242 in the “Annales des Ponts et Chaussées” for 1869). The writer is also informed that M. Guillemain in his lectures at the Ecole des Ponts et Chaus- sées derives A’, B’ and C’ by considering only # Fic. 14. the projections normal to & of the portions of the joint mz as shown in Fig. 14. m™m n All mathematical methods of designing dams are based upon a distribution of pressure according to the laws explained in this chapter. Great caution must be used, however, in apply- ing the formule given to cases where the resultant pressure is sufficiently eccentric to produce tension. In a well-designed dam this condition ought never to exist. Where part of the masonry is under pressure and part in tension, there will be great uncer- tainty in determining the distribution of the stresses. The usual method in such cases has been to neglect the tension and to use formula C for finding the pressure. In the method of designing profiles which will be given in the next chapter, we shall limit the position of the lines of pressure to the centre third of the profile, avoid- ing thus all tension and calculating the maxima pressures by formula A or B. 18 DESIGN AND CONSTRUCTION OF MASONRY DAMS. CHAPTER III. THEORETICAL PROFILES. In the following investigations— “Front” will signify “down-stream.” “ Back” will signify “ up-stream.” P will denote the line of pressure, reservoir full. P’ will denote the line of pressure, reservoir empty. The unit of weight will be one cubic foot of masonry. All linear dimensions will be expressed in feet. the the the the the the the the = the y & SSN SSS Rw HS I | | ose ye = the the the a 2r a? 6r the the = the the the the the top width of the dam. unknown length of a joint of masonry. known length of the joint above +. depth of a course of masonry (assumed generally = 10 feet). distance of P from the front edge of the joint x. distance of P’ from the back edge of the joint x. distance of P’ from the back edge of the joint 4 distance between P and P’ at the joint +. coefficient of friction for masonry on masonry. cohesion of the masonry per square unit. ° specific gravity of the masonry. depth of water at a given joint x. = the horizontal thrust of the water. = the moment of # about any point in the joint x. total weight of masonry resting on the joint x. total weight of masonry resting on the joint 4 resultant of H and W. resultant of the reactions. angle made by & with a vertical line. limiting pressure per square foot at the front face of the dam. limiting pressure per square foot at the back face of the dam. g >p will be generally assumed. There are four ways in which a dam may fail: Lm Ist. By overturning. 2d. By crushing. 3d. By sliding or shearing. 4th. By rupture from tension. THEORETICAL PROFILES. oe To insure ample safety against all these causes of failure, we shall require the pro. files which are to be determined to comply with the following conditions: Ist. The lines of pressure must lie within the centre third of the profile, whether the reservoir be full or empty. 2d. The maxima pressures in the masonry or on the foundations must never exceed certain fixed limits. 3d. The friction between the dam and its foundation, or between any two parts into which the dam may be divided by a horizontal plane, must be sufficient to prevent sliding. The first of the above conditions precludes the possibility of tension, and insures also a factor of safety of at least 2 against overturning, as will be seen from the following: Suppose the lines of the reaction A’ and Fic. 16 of W to intersect the joint 7 at the limits of its centre third, as shown in Fig. 10 Taking the moments of the forces Rk’, W and A, which are in equilibrium, about the point ¢, we find Had Wi a a Se If the moments are taken about the front edge a, the lever-arm of IV will be doubled, eo [as coley b while that of 7 remains unchanged. The factor of safety against overturning is there- fore 2. It is evident that if the line of action of W or &, or both of them, should intersect 7 within its centre third, the factor of safety against ~overturningy w..._' factor -- of stability, would be greater than 2. ae The resistance of a-dam to sliding has gen(erally been calculated in the following manner : If we conceive the wall to be cut by a herizontal plane at a given joint 2 there will be two forces which will prevent the upper ee from sliding on the lower one: Ist. The cohesion of the masonry. 2d. Friction. [ We must have for equilibrium HW + ab ee ee ee ee ee ee \ The value of ¢ is considerable for good masonry, but cannot be accurately determined. If we consider c/ as a margin of safety, and place Ss Be Vos ay 2 bed oe, “Ss ample security against sliding will be insured. These formula may also be applied tc the base of the dam, in which case ¢ = the adhesion of the base to its foundation and the resistance die to the irregular'ties of the latter. The value of f has been, inken by different writers from .67 to .75. To find in , any given case what vulue “of f would prevent sliding, we have, from ae and Fig. 10 Be ied I ee he : hy 29 DESIGN AND CONSTRUCTION OF MASONRY DAMS. The maxima pressures in the masonry or on its foundation are to be determined by formula A, B or C. In applying these, however, we have followed Prof. Rankine’s method of neglecting the vertical component of the water-pressure. As the early French writers adopted very low limits of pressure (6 kilos. per square centimetre), the up-stream sides of the profiles which they designed had considerable slope. The vertical component of the water-pressure became thus an important factor, which had to be considered in the calculations. Experience has since demonstrated that much higher limits of pressure may be safely adopted, especially for the up-stream side, which, under these circum- stances, becomes very steep. By neglecting now the vertical component of the water- pressure, when the back face is nearly vertical, only a trifling error in the direction of safety will be made, as the force which has been omitted adds to the stability of the dam, and diminishes slightly the pressures at the front face by moving FP up-stream. There are several additional reasons for adopting this course, which will be explained in Chapter IV., page 30. It is impossible to express the thickness of a dam at a given joint by a formula which will satisfy at once the three conditions given on page 19. However, it will always be found within the limits of practice that by satisfying the first two of them we have also fulfilled the third. The reason of this fact will be explained in Chapter V. We shall base the thickness of a dam, therefore, upon the first two general conditions. In establishing the necessary equations, we shall consider only one lineal foot of a wwe ge thrust of the water simply by its own weight. Al- 1 of a dam to form a rigid monolith of homogene- : imposes of calculation to be divided into SE wy asurisvlilal plates. The profiles will be proportior —-- ~——s with reference to the hydrostatic pressure of the water, the highest elevation of .. :e being taken at the level of the top of the dam. Theoretically, this would alli .. lake the top width of the wall equal to zero. However, to resist the action of i¢ shocks from floating bodies, and to serve as a means of communication, a. it always have more or less top width, which will be determined solely by sp: ‘derations, depending upon the locality, etc. To obtain a profile contain: ast area which will fulfil the requirements, .we shall calculate the joints to be ae given limits. With the conditions advar S fs chapter, a given joint of masonry will always Fic. 16 i be composed of three parts, as shown # in Fig. 16, We can write, therefore, —— | SRP Pes ss ae : { ( a | but ; ey = M= W2, | | | since & is the resultant of H and W. oe As we shail adopt polygonal outlines for the sheoretical profile, each cue ‘of \ \ a : ¥ { ¥ nN THEORETICAL PROFILES. 21 masonry will have a trapezoidal cross-section, and we will have, recollecting that—the—~ unit of weight is one cubic foot of masonry, ‘ Wawt (ee ee ee Therefore M = = —— . . ° ° ° eo e. e@ e ° (1) f+ mn,’ w +( - jt which value being substituted in Equation (1) gives M ' += U + ——_—,;_— +2. e ° ° e e e ° ° (II) Jt ae ( + )a f By substituting for « and xz their proper values, which result from the conditions im- posed, we can determine by means of Equation (II) the exact theoretical thickness of a dam at intervals, taken as small as may be desired. In the upper portions of the profile, where the pressure in the masonry is incon- siderable, « and x will be determined solely by the Ist condition, according to which =F d 4 eg er te the maxima pressures at the joints to be calculated must be kept on these limits by substituting values for # and x derived from formula A (page , viene id a fey rata When, however, the pressures in the masonry reach the limits ~ and g, 24 ae 24 gx’ Ts = “= a a - © 8 6 (J) 21= = ae 6’ ae #8 « (K) in which Waw+ (Ee... OD As -we shall commence the design of a dam with a given top width, determined by special considerations, the upper portions of the profile will necessarily have an excess of material as regards resistance to the hydrostatic pressure of the water. To obtain the minimum area of profile, both faces must be continued vertical until one of the limiting “conditions is reached. Overhanging faces would give a smaller profile, but should not be sit atin sted, for obvious reasons. / ee “The upper portion of the profile ought, therefore, to be a rectangle. P’ will pass \~ hrv~ugh its centre, but, owing to ( water-pressure, P will gradually approach the front rage a é face, reaching eventually a joint + a, where “= Zz | ‘blo the top : a dame obiskg fom At Hy \ To hind the 4 yen Ut this ” 22 DESIGN AND CONSTRUCTION OF MASONRY DAMS. The front face must now be sloped to keep P on the limit of the centre third of the FIG. 17. profile; but, as P’ is in the centre of the w m joint just found, the back face may be con- I tinued vertical for a series of courses. Fig. 17 shows the cross-section of one of them. We shall again employ Equation (II) to find x, placing «= As P’ will lie within n x the centre third of x, x will not be deter- mined by the limiting conditions, but can be found by taking moments about the back edge of the course. The moment of W= Wn. The moment of w= wz. +1 bho yt : To find the moment of the trapezoid ( + “\i divide it into two triangles, as shown in Fig. 18. Fre, 18, O l a5 gue h 6 o = 2 © ~ o e & e As the centre of gravity of a triangle equals the centre of gravity of three equal weights placed at its apices, we may substitute for the trapezoid 6 weights, as show in the figure. We will find moment of (Ei =(¢@+44+4 re. The moment of the whole weight must equal the moments of its parts; therefore Wn = wm + (et + le + PE; whence, placing W>=w+ (=). : ah ‘ (a? + le + Le + win we obtain . a= ek . We» bes Je ye ae Rot < 2 hstitucug this*Vvalue and also u Ls =" os 0), Ye fi. BONS ate vane ties we Pas cae ies \ "6 PHT Pee = Seem $a) d i opt a Equation (>). may VagbS, “se for a series of ‘ointer tet one is! ‘found we; ‘* . > “ pate emus THEORETICAL PROFILES. 23 For the next course both faces will have to be sloped so that w = x =>. Substituting these values in Equation (11), and reducing, we obtain . e+ (2 4 1) 2 Pig 2, ge ae Se . Bo de Thus far we have only been obliged to introduce the first general condition (page 15) into our formule, as the pressures in the upper portions of the profile do not reach the limit. However, in applying Equation (3) to a series of joints, we must always, after finding a value for x, calculate the maxima pressures, both with the reservoir full and empty, to see whether they reach the limit f or g. This will always occur first at the front face, as we have assumed # < g. When the limit f is reached, the next seriés of joints must be found by substituting in Equation (11) 24 px’ x te = — a te D n= 3 ow +S) a) 3 ee 7 2 after reducing, we obtain {= 6a : y > ay ete (4) This equation may be employed oe eee pressure is reached at the back face. We must then determine the next joints by substituting in Equation (11) ’ 2% pr 3 fet 6w +S a 2% gx / / A p49 —M— 22a 4S) 6. eh We Boer @ Gob om (5) » (K) 4 ‘After reduction we find ‘Equations (1) to (5) enable us to calculate successively the exact lengths of all joints, commencing at the top of the dam. However, Equations (3), (4) and (5), which apply to _that portion of the dam where both faces slope, determine only the lengths of the joints, but not their position. This mayebe fond by the following equations, which determine the batter of the back face of the~given course; Fic. 19. L | aol are -< Ng 24 DESIGN AND CONSTRUCTION OF MASONRY DAMS. are known. The quantity to be found is y, the batter of the back face. The trapezoid ad i eres will be replaced by six weights, as already explained in finding Equation (2). As the moment of the whole weight must equal the sum of the moments of its parts, we have, taking moments about the back edge of x, Wa = wlm+ 9) + E+ 29+ 20+ a2 +E CEI 6 ee OD For Equations (3) and (4) the value found for y must make 2 = Substituting this value in the above equation, and also Ww = w+ (\,, ee oe 4.82253 5 ee) = we shall find, after reducing, __ 2w(4 — 3m) — hl* ~ 6w+th(2aitxz .° * * ° For Equation (5) we must have i r,t | ee a = a Substituting this value in Equation (III) we obtain, after reduction, w4r — 6m) + thx —1)+ #(h — Q) J = 6w +- (27+ x) oe 8 ¢ e e© © - (7) Equations (1) to (5) are simply modifications of the general Equation (1), resulting from the changes in the controlling influence of the limiting conditions in the various parts of the dam. In the upper portions of the profile, the limiting of the positions of the lines of pressure to the centre third of the profile is the only important condition, whereas in the lower portions the amount of pressure in the masonry becomes the controlling considera- tion. What adds to the mathematical difficulties of finding simple equations for determining the proper profile is the fact that the changes in the controlling influence of the conditions do not occur simultaneously at the front and back face. i. _- Feeling convinced that with such complicated requirements no regular mathematical — - curves or lines could be found for bounding a profile which should fulfil all the given 4 conditions and at the same time involve a minimum amount of masonry, the \riter, instead of following the methods hitherto proposed for determining at once a practical profile, adopted the plan of first finding by means of the equations given a theoretical profile upon which to base the practical design. The ¢heoretical profile resulting from calculating the 4 Bn required thickness of a dam at regular intervals will have polygonal faces. By taking the [ value of / sufficiently small, we can determine a profile which shall fulfil all the given condi- Mig ee aa tions and at the same time contain practically the minimum area. The only modificat’ \ that remains to be made in this theoretical type to arrive at the practi eth a8 simplify its faces by fitting curves or straight lines to the theoretical for AR. hy changes, made for this purpose, will be but slight as regards the ye ‘| é 4 g a al a! THEORETICAL PROFILES. 25 In applying the equations to practical calculations we have assumed % = Io feet, as the numerical work is thereby greatly facilitated, and the transition from one equation to the other is so gradual that no difficulty is experienced in selecting the proper one.* gat The equations given thus far have been based upon the conditions of Prof. Rankine. They are the only ones that we shall advance for designing profiles. For sake of com- parison, however, we shall show how Equation (I1) may be adapted to the French condi- tions as given by MM. de Sazilly, Delocre and Pelletreau, with the difference that, for the reasons stated on page 20, the vertical component of the water-pressure will be omitted. The main difference between the principles adopted by these engineers and those of Prof. Rankine is, that in the former no restriction is placed upon the positions of the lines of pressure. So long as low limits of pressure are used no danger will result from this neglect, as P and P’ will lie practically within the centre third of the profile. But when we take high limits of pressure—and the tendency of late has been in this direction—the lines of pressure will be very eccentric. With such limits the back face of a dam will be vertical for a great depth, and the effect of neglecting the vertical component of the water-pressure is therefore slight. The profile may be found by the following method: The upper portion of the profile will be a rectangle, but instead of terminating where P reaches the limit of the centre third of a joint, it will be continued until the pressure at the front face reaches the limit . Equation (), «# =u+v-+42, is to be used with the following substitutions : a? 6ra Si a i 2? a 2a a= iy (from formula A) if w = “= 2 (from formula C) ifu< a in which W = ad. If “«> e we obtain a brid —f7P HO, s sh ee eR we » « (8) Ifu a ? 3 a) _ __A i *A practical example of the use of equations (1) to (5) is given } the ‘Alypendix, page 40? \ 26 DESIGN AND CONSTRUCTION OF MASONRY DAMS. af w+ (EA h C= )) (from formule C and H) ifa< a and for z the same value found for Equation (2) by taking moments around the back edge of the joint, we obtain— Ds Ifu>-, os pe +2we =6wm+hPt6M. . . 1. 6 6 © © © © (10) x If w<-, 3 272 ai(h a = )+ x (50 4 lh — 5 (2h + )) = 3M + 30m + as +5 (20" + 2wlh + = (11) As in the previous case, we can only determine by trial which of the above equations to use. So soon as the limiting pressure has been reached. at the back face, both faces of the dam will have to be sloped in order to keep the maxima pressures within the prescribed limits. Sazilly, Delocre and Pelletreau used the same limit of pressure for both faces; we shall, however, introduce p and g as in Equations (1) to (5). Let us first suppose that P lies within the centre third of a joint x, while / lies without. Substituting in Equation (11) w= _ ____fF ___ (yy, © (w+ (4) 2(w+ (+2),) n= —_——__--——_ (from formule C and H), we obtain x'(hq + 9p — h’) + 2[(¢ — 2h) (2w + lh) = 69M + lh(th 4+-4w) + 4w*. . . (12) Should P lie without and P’ within the centre third of a joint, we must employ Equation (12), transposing simply the position of p and g. If both P and P are within the centre third of the joint, we obtain Equation (5), given on page 19. Sec Finally, if P and P’ both are outside of the centre third, we obtain #[ 5G = ie) | - | 30 + uf os Isht\— awa) | = 2] aw" + i 4 22) | +34, (13) ore J Pq ae, a in which z= ale The above equations cover all the cases that can arise, but some of them will never be needed for actual calculzg.ions. The value of y will be found by using Equation (6) or (7), except when P’ lies outside of the centre third of eee In this case er, / / THEORETICAL PROFILES. 27 2 AW — 6wm — h(x? + 214+ 1’) 6w + Wal + 2) be BR SB Baw ee ee HID In the French methods of determining profiles, in which P and P’ are not restricted to its centre third, there are always more or less trial-calculations involved, as it is not known in advance whether to employ formula A or C for expressing « or x. However, if we assume #4 = 10 feet, the change from one equation to the other is so gradual that trial-calculations will seldom have to be employed. In applying the equations given in this chapter to practical examples, it is advisable to.check the calculations by some other method. This may be done readily by the principle of moments, as follows : = Assume a vertical axis at a convenient distance from the back face. After having found a value for a joint x by solving the proper equation, divide the corresponding course into a rectangle and one or more triangles by vertical lines, as shown in Fig. 20. Fic. 20. Ww L ! 3 | N 4 | Cc IB aw The moment of the weight w resting on the joint 7 about the axis is supposed to be known from the previous “check-calculation.” Adding the weights of A, B and C (the parts into which the course has been divided), expressed in cubic feet of masonry, to the weight w, and the moments of A, B and C about the vertical axis to the moment of w, we obtain W (the total weight resting on the joint x) and its moment about the axis. By dividing this moment by the weight W, we obtain the distance of the centre of gravity of the profile above the joint x from the axis; in other words, we have found where P’ (the line of pressure, reservoir empty) cuts the joint x. M JM = moment of water, Ww’ W = total weight, we find the distance from P’ to the line of pressure P (reservoir full), measured on x. We can verify thus whether P and P’ are within the prescribed limits. By means of formule A, B and C the maxima pressures at the joint x can be found, both for reservoir full and empty. These pressures should be within the given limits. From the formula (G), v= 7, in which | The value of the coefficient of friction which is necessary to prevent sliding can be found from (F) and Fig. 15 as follows: vy 3u = See 6. ee ee ee oe eG f= tana Za (L) 3 The factor of stability, which we shall denote by S, can be obtained thus: s= Were (see page 19), but WZ = vW (from G); hence S= wee ‘ (M) 28 DESIGN AND CONSTRUCTION OF MASONRY DAMS. CHAPTER IV. VARIOUS APPLICATIONS OF EQUATIONS (1) TO (14). IN the preceding chapter we have found the necessary equations for calculating theoretical profiles. We will now apply them to practical examples from which important deductions may be made. Necessity of Limiting the Positions of the Lines of Pressure.—The maxima press- ures in existing dams vary from 6 to 14 kilos. per square centimetre (about 6 to 14 tons per square foot), as may be seen in Table XXIII. The limit adopted for the Furens Dam was 6$ kilos. per square centimetre; for the Ban Dam, built subsequently, it was raised to 8 kilos; and M. Graff in his memoir* on the former structure gives a profile based upon 14 kilos. per square centimetre, which pressure has been safely sustained in the Almanza Dam for three centuries. To study the effect of adopting the French conditions (see page 25) with high limits of pressure, we give in Plates VIII. and IX. two profiles calculated by Equations (8) to (14), assuming for the first, p= 8 kilos. per square centimetre, g = 10 kilos. per square centimetre; and for the second, p= 97= 14 kilos. per square centimetre. Tables VIII. and IX. give the necessary details. The danger resulting from placing no limits to the positions of the lines of pressure is very apparent in these profiles; especially in No. 2, which corresponds to the one given by M. Greff for a limiting pressure of 14 kilos. per square centimetre. In this case the lines of pressure are so eccentric in the upper part of the profile, that a dam built according to this design would be very unsafe, and by no means have a “profile of equal resistarico——_ » Although experience proves that pressures as great as 14 kilos. per square centi- metre may be safely sustained in the lower portions of a dam, where the lines of press- ure generally lie within the centre third of the profile; yet in the upper portions such pressures cannot be permitted, as they can only result from a dangerous eccen- tricity of one of the lines of pressure. We see, therefore, the necessity of adopting some principle besides the limiting of the stress on the masonry, in order to insure perfect safety in a dam. If we add to the French conditions the one given by Prof. Rankine, which limits the positions of the lines of pressure to the centre third of the profile, no danger can “Ir the ‘‘ Annales des Ponts et Chaussées,” Sept. 1866. VARIOUS APPLICATIONS OF EQUATIONS (1) TO (14). 29 arise in the upper portions of a dam, designed on this basis, on account of a high limit of pressure being assumed. Such a wall would always have a factor of safety against overturning of at least 2; would have no part subject to tension; and would also have ample safety against sliding or shearing, as will be shown in the next chapter. Weight of Masonry.—The early writers on the subject of dams assumed the specific gravity of the masonry as 2. M. Krantz, in his book on “ Reservoir Walls,” * points out that this assumption introduces an error into the calculations, as the true specific gravity of good rubble masonry built of granite or limestone is about 2.3. M. Bouvier + gives the specific gravity of the masonry in the Ternay Dam, constructed of granite, as 2.36; M. Pochet ¢ places that of the Habra Dam, which was built of calcareous stone, at 2.15. ; To show the influence of the weight of the masonry upon the form of the profile, we have calculated four profiles by Equations (1) to (7), assuming the specific gravity of the masonry respectively at 2, 241, 24, and 24. The corresponding values of the moments of water (JZ) are: of eb et 12” 12” 14’ 15’ the weights per cubic foot of masonry being 125, 135.41, 145.83, 156.25 lbs. As the exact average weight of the masonry in a dam is generally unknown, we may adopt approximate whole numbers as the divisors of J, in order to facilitate the numerical work. The four profiles are shown in Plate X. Tables X., XI., XII. and XIII. give the details. If we compare the corresponding areas of these profiles at different depths, we shall find that for a depth of about 190 feet the area of profile diminishes as the weight of the masonry increases. For greater depths, however, this law will be reversed. Not only will the amount of masonry required for a dam depend upon the specific gravity of the masonry, but this factor will also affect the form of profile, as will be noticed in Plate X. Vertical Component of the Water-pressure.—Let us next examine the effect of including the vertical component of the water-pressure in our calculations. Taking profile No. 5 (Table XII.) and recalculating the maxima pressures at the front face, including the vertical component of the water-pressure in the total weight resting on a joint, we find as results the figures given in the table at the top of the next page. This table shows that although by including the vertical component of the water- pressure a greater load has been placed upon each joint, yet, owing to the fact that the line of pressure has been moved back from the front face of the dam, the maxima pressures will be diminished. The difference between the pressures calculated with and without the vertical com- ponent of the water-pressure increases gradually, amounting to 15 per cent at a depth of 200 feet. Now, this gradual reduction of the amount of pressure at the front face as its * Published in Paris in 1870. t ‘Annales des Ponts et Chaussées,” Aug. 1875. ¢ Ibid., April 1875. 3° DESIGN AND CONSTRUCTION OF MASONRY DAMS. Maximum Pressure. 1 2 3 4 Dertu or Water. | Vertical Component | Vertical Component Numbers in of Water included of Water excluded | Column 3 divided by in Cubic Feet of in Cubic Feet of Corresponding Num- Masonry. Masonry. bers in Column 2. 70 81.26 82.5 IOL 80 86.31 88.4 102 go 94.09 96.2 102 100 102.16 104.4 102 IIo IIo.10 I12.3 102 120 108.91 112.3 103 130 108.23 II2.3 104 140 107.54 112.3 104 150 106.96 112.3 105 160 106.55 112.3 105 170 103.88 112.3 108 180 101.77 II2.3 IIo 190 98.00 T12.3 114 200 97-22 112.3 115 batter increases is precisely what one of Prof. Rankine’s conditions requires. As this eminent writer admits that it is impossible, in our present state of knowledge, to find the law this diminution of stress ought to follow, it would seem sufficient to effect this object by simply omitting the vertical component of the water-pressure in the cal- culations. There is another reason for adopting the above method. Formule A, B and C (page 10) have been obtained by assuming a dam to be perfectly rigid. It has been pointed out in Chapter II. that we must use caution in applying these formule, which after all are only approximately true, to extreme cases. Now by assuming in the case of a dam having a steep back face that a column of water resting near one edge of a long joint relieves the pressure at the other edge, we are carrying the hypothesis of rigidity to an unsafe extreme. It is certainly safer to overestimate than to underestimate the max- ima pressures. There is no theoretical difficulty in modifying the equations already given so as to include the vertical component of the water-pressure; but we shall obtain an equation of the fourth degree of such length as to be of no practical value. Various approximate methods of finding the desired result can readily be found. Thus Equations (1) to (5) may be used with the value of g increasing gradually below the joint, where the back face com- mences to slope, the increase being based upon the above table. When the pressures are afterwards recalculated with the vertical component of the water-pressure included in the loads, they will be found to be very near the fixed limit. The reasons given above show the advisability of neglecting the vertical component of the water-pressure, where VARIOUS APPLICATIONS OF EQUATIONS (1) TO (14). 3I the up-stream face of a dam is steep, as any error that may result therefrom will be on the safe side; whereas by including the component in the equations we probably err in the other direction. , Inclined Joints.—In making calculations for the profile of a dam, it is customary to assume it to be divided into courses by horizontal joints. As these are imaginary, there is no theoretical reason why they should be assumed to be horizontal. The ques- tion naturally arises, what the effect would be of making calculations for inclined joints. In Plate XI., profile No. 5 is shown with joints radiating from points in the back face of the wall. By examining Table XIV., which gives the results of the calculations made for these joints, it will be seen that by inclining them downward from the back of the dam the maxima pressures are reduced; whereas by inclining them upward the opposite effect will be produced within certain limits. The angles made with a horizontal line which give the maxima pressures at a certain depth of water vary from 20°-30°. The increase of pressure resulting from inclining the joints, which at a depth of water from 60—110 feet amounts to only 14%, is 41% at a depth of 160 feet. In making these calcu- lations the weight of the masonry below the joints has been omitted, as though the dam were cut in two parts. While this supposition is rather extreme, good rubble masonry would doubtless bear the resulting pressures. Should we desire to increase the thickness of a dam on account of the pressures produced upon oblique joints, we can modify the Equations (1) to (14) according to M. Bouvier’s method,* so that the limiting pressure will not be exceeded in joints drawn per- pendicular to the resultant pressure. Profile on Bouvier’s Principle.—Let us change profile No. 5 in accordance with the above. No alteration is necessary for the first go feet from the top of the dam, as the only important consideration for this part is that the lines of pressure must be within the centre third of the profile. Below this depth, as the pressures on the joints will be parallel with the resultant, we can take g for the limiting pressure at both faces. The corresponding limit of vertical pressure at the front face will be g cos a, in which @ is the angle which the resultant (R) makes with a vertical line. The maxima pressures at the back face are of course calculated for horizontal joints, as they occur, when the reservoir is empty and &, therefore, vertical. To make Equations (1) to (14) agree with M. Bouvier’s principle we need only substitute for g the pressure g cosa. The angle (a) is unknown, as its value cannot be determined until we have found the corresponding joint. But the difference in the inclination of the resultants from .joint to joint is so slight, when these are only ten feet apart, that we can use the value of @ for the joint above the one to be determined, in the equations. This is the method we have followed in modifying profile No.5 to agree with Bouvier’s principle. The profile obtained thus is shown in Plate XII., the details being given in Table XV. By examining this table it will be seen how trifling the differences are in the value of (@) from joint to joint. The bottom width of the profile found by Bouvier’s principle is 196.35 ft., and its area 15,662 sq. ft.; whereas for profile No. 5 we have respectively 190.98 ft. width and 15,157 sq. ft. area. Although we have given this method for taking the obliquity of the pressures, when the reservoir is full, into account, our present knowledge of this subject is so uncertain * See page If 32 DESIGN AND CONSTRUCTION OF MASONRY DAMS. that it is a useless refinement to introduce it into the equations. For all practical pur- poses we need only consider horizontal joints, applying Equations (1) to (7) with such values for ~ and g as experience warrants. , Comparison of a Theoretical Profile with Rankine’s Logarithmic Type.—Equations (1) to (5) have been based upon the conditions given by Prof. Rankine. The theoretical profile found by applying them differs, however, considerably from the logarithmic pro- file designed by that eminent engineer. For sake of comparison we have made calcula- tions for a theoretical profile based upon the data used by Rankine. Plate IV. shows the profile and also the logarithmic type. Tables III. and IV. give the details. For a depth of 140 feet both profiles are based upon exactly the same conditions and data; but below this depth there is a slight difference, which requires explanation. Prof. Rankine states, namely, in the report we have quoted on page 4, that the limit- ing vertical pressure should be diminished as the batter of the front face increases. He did not advance any law for this diminution, but simply designed his profile type in such a manner that the stress at the outer face at a depth of 160 feet would equal the pressure sustained in the Furens Dam at the same depth, 6} kilos. per square centimetre. Having adjusted the logarithmic curves, adopted for the outlines of his design, with ref- erence to this stress, and also to keep the lines of pressure practically within the centre third of the profile, Rankine was unable to regulate the pressures in the lower portions of the profile, as they are determined without any regard to theory by the logarithmic curves. He considered it an advantage that the outlines chosen for his profile-type made the pressures diminish rapidly at the front face of the lower portions of the dam; but if his principle be correct, the steeper the front face is kept within safe limits of pressure, the better. In our theoretical profile we have retained the same limit of pressure for all parts of the dam, the result being shown in the following table: Ree | Beare THEORETICAL PROFILE. Deptu.* Feet. Angle. er Angle. oe Masonry. Masonry. 100 52° 47’ 122 54° 14’ 103 110 49° 17’ 124 54° 21’ II2 120 45° 44' 123 54° 30’ 122 130 42° 09’ 11g 48° 56’ 125 140 38° 37’ 114 45° 21’ 125 150 35° 11’ 107 44° 07’ 125 160 31° qt 99 42° 59) 125 170 28° 46' go 41° 57’ 125 180 gee By; 81 40° 59' I25 190 23° 19 73 39° 13' 125 200 20°. 40" 64 38° 09! 125 The angles given above are made by the tangents of the front logarithmic curve and the lines forming the front face of the theoretical profile, respectively, with horizontal planes. VARIOUS APPLICATIONS OF EQUATIONS (1) TO (14). 33 As the profile calculated by our equations has a steeper face than the logarithmic type, it can safely sustain greater pressures. At a depth of 180 feet the difference in the pressures in the two profiles for the same angles is about 8 per cent; at a depth of 200 feet it is less than 10 per cent. As the actual pressures will be somewhat reduced from what is given in the table by the vertical component of the water-pressure, which has been omitted in the calculations, there seems no necessity of reducing the limit of pres- sure in the lower portions of the dam. Rankine gives the logarithmic profile only for 180 feet depth of water. If it be con- tinued, the front face becomes very flat. Instead of such a profile having great strains near the front face at the base, it is much more likely that the thin toe of masonry at the front face transmits but little pressure, the stresses following short direct lines towards the base. The theoretical profile agrees for a depth of 140 feet exactly with the conditions and data assumed by Prof. Rankine for his logarithmic profile, and the differences below the depth are but trifling. It will, therefore, be interesting to compare the corresponding areas of the two profiles (see Tables III. and 1V.). The following comparison shows that the differences are always in favor of the theoretical profile: Rankine’s Loga- 7 Differences in Favor mene kee Oe Hee Area in Square Feei. Theoretical Profile. ° ° ° oO Io 200 187 13 20 426 374 52 30 679 565 114 40 973 792 181 50 1,303 1,074 229 60, 1,674 1,419 255 7° 2,098 1,842 256 80 2,577 2,347 230 go 3,119 2,930 189 100 3,734 3,589 145 IIo 4,431 4,322 109 120 5,221 5,129 92 130 6,116 6,018 98 140 7,129 7,O1L 118 150 8,278 8,116 162 160 9.581 9,337 244 170 11,055 10,678 377 180 12,728 12,142 586 Igo 14,621 13,746 875 200 16,765 15,510 1,255 From Plate IV., and from what has been said above, it will be seen that while the logarithmic profile has sufficient strength and graceful outlines, it is not a close approxi- mation to the correct theoretical form. In the next chapter we shall show how the theoretical profiles calculated by the equa- tions we have given may form the basis of practical designs for masonry dams. 34 DESIGN AND CONSLRUCLiI0N OF MASONRY DAMS. CHAPTER V. PRACTICAL PROFILES. THE practical profiles for masonry dams, which we shall establish in this chapter, will be based upon theoretical types containing the least areas consistent with the following conditions: Ist. The lines of pressure must lie within the centre third of the’ profile, whether the reservoir be full or empty. 2d. The maxima pressures in the masonry or on the foundation must not exceed certain safe limits. 3d. The friction between the dam and its foundation, or between any two parts into which the wall may be divided by a horizontal plane, must be sufficient to prevent sliding. To these conditions, in which only the hydrostatic pressure of the water is con- sidered, we must add: 4th. The dam must be sufficiently thick in all parts to resist the action of waves and shocks from floating bodies. As what constitutes sufficient strength with reference to the last of the above conditions is a matter of judgment, in our present state of knowledge, we shall first determine the correct form of profile as regards the first three conditions, and modify it subsequently to satisfy the fourth. The width of this profile at the highest elevation of the water-surface should evidently be zero. Inthe upper part of a dam the pressures in the masonry are so inconsiderable, that only conditions 1 and 3 need be considered in proportioning the profile. Within the limits of practice, however, a profile based upon the former condition will always satisfy the latter, as will presently be shown. The profile which contains the minimum area consistent with condition 1 forms a right-angled triangle having its vertical side up-stream. As in such a section the centre of gravity of the area of the profile above any joint lies in a vertical line passing through the up-stream limit of the centre third of this joint, it follows that the line of pressure F’ (reservoir empty) will limit the centre third of the profile up-stream. Denote the base of the triangular profile by +. By changing its length the value of < (see page 18) may be made to vary within the limits o and 7 In Equation (1), M ta=U+V+ Haut T+ x (see page 20), let us substitute j=; we. oe wat. 3 3 6r 2 PRACTICAL PROFILES. 35 We shall obtain, by reducing, Ge 8 Bete ee we ee ew SD As x is proportional to d, the line of pressure P (reservoir full) will cut all horizontal joints in like manner as the base, and will form thus the down-stream limit of the centre third of the profile. We conclude, therefore, that the triangular profile whose base is given by Equation (15) has the minimum area consistent with condition 1. Now let us investigate whether it fulfils condition 3. We have, from Equation (F), page 19; a’ xa a Hf f=p=tana; but =~, er Substituting these values in Equation (F), we find oe 4 we oR SD Vr Let 8 = the angle between the faces of the triangular profile: tan 6 = QR Substituting for x its value given in Equation (15), we obtain tan 6 = = Hence we have f=tane Stan f= Scie Se ae plc Ge SS oe Vr The coefficient of friction necessary to prevent sliding equals, therefore, the tangent of the angle at the top of the triangular profile. Taking y= 2 and r = 3 as the extreme limits of the specific gravity of the masonry that may occur, we find f to vary between 0.707 and 0.577. M. Krantz and other authorities place the limiting value of / at 0.75. The triangular profile satisfies, therefore, condition 3, and may be continued until the limit of pressure is reached. The maximum pressure at any joint of this profile (reservoir full or empty) is given W a by formula B, page 10, according to which p = aa As W= =, we have The depth of any joint below the surface of the water expresses, therefore, the maximum pressure in that joint in feet of masonry, whether the reservoir be full or empty. When the limiting pressure has been reached, the triangular profile must terminate, and be continued by means of Equations (4) to (7) (pages 23 and 24). ; Plate XIII. shows a triangular profile for a value of r = 24, which we shall call Theo- 36 DESIGN AND CONSTRUCTION OF MASONRY DAMS. retical Type No. I. Table XVI. gives the necessary dimensions, etc. It is sufficiently strong in every respect to resist the hydrostatic pressure of the water; but to resist the action of waves, as required by the fourth of the given conditions, it must be modified. The first step will evidently be to give it sufficient width at the top to resist the action of waves and shocks from floating bodies. If the dam is also to serve as a bridge this width may be still more increased, and will generally be between the limits of 2 to 20 feet. The top of the wall ought also to be raised a certain height above the highest probable elevation of the water-surface. As the height of the waves will depend largely upon the extent of the reservoir and the depth of the water, high dams ought generally to have a greater supereleyation above the highest water-surface than low ones, and ought also to have a greater top width. The following table, taken from M. Krantz’s book on “Reservoir Walls,” and M. Crugnola’s work on “ Retaining Walls and Dams,” gives the top widths and superelevation above the water-surface recommended by these engineers: Top WiptH or Dam, In METRES. Top or Dam aBove WATER, IN METRES. Dertu oF WaTER, IN METRES. 3 Krantz. Crugnola. Krantz. Crugnola. Scat een dene ene eee ee 2.00 1.70 0.50 0.50 TO, cece eee c cree cece neces 2.50 2.00 I.00 0.90 TGs cue apseieareaee Kea sees 3.00 2.30 1.50 1.30 DOs scmaewrwee oe alaine gape wae 3.50 2.50 2.00 1.50 Bo. Lcsuen ae ts Saeeatacioeesis 4.00 3.00 2.50 2.00 BG. diene eaaasasuser 4.50 3.50 3.00 2.40 iB Staaxairsipie gadjalcva aaa aya arsvecsiararets 5.00 4.00 3.50 2.80 BOM eeicierinecceesicn ds aee 5.00 4.25 3.50 3.00 BB siareeh wus ann SaKislewavewaepunt 5.00 4.50 3.50 3.25 BOnseatee ses eeseorvegaven 5.00 4.75 3.50 3.50 A good rule for ordinary cases is to make the top width of the dam and the super- elevation of its crown above the highest water-surface one tenth the height of the dam, limiting the former to a minimum value of 5 feet, and the latter to a maximum value of 10 feet. While it is always advisable to provide a reservoir with an overflow-weir sufficiently large to prevent the water from passing over the dam, yet the safest course in designing the profile will always be to assume the level of the water at the top of the dam. Greater freshets may occur than those. upon which the size of the waste-weir was based; or, a great demand for water may lead the owners of the reservoir to raise the level of the overflow. In all the calculations for this book, the water-surface has been assumed at the top of the dam. We shall now investigate what the effect will be of giving a certain top width to the triangular profile. The upper part of the wall will now evidently have a surplus strength with reference to the first three conditions. As this increase is only required near the top of the dam, we shall seek to reach the triangular profile in the shortest practical manner PRACTICAL PROFILES. 37 by making the front face vertical until it intersects the sloping face of this profile. Plate XIV. shows the new design, which we shall call Practical Type No 1. Let us determine to what extent the positions of the lines of pressure P and P’ wili be changed. In Fig. 21 let a = top width of dam; Fie. 21, 6 = length of vertical part of front face; A = triangular profile at a given depth; B= triangle added at the top of 4; 8 = angle between the faces of A. ad Using the letters given on page 18, we find: A Area. Moment about Back Face. er dad’ .tan 8 a’*. tan’ 2 6 2 3 2 7 & .tan B & . tan’6 2 3 H __ Moment of A + Moment of B _ tan 6 (d* + 20°) sae ”“=—~Krea of A + Area of B ~~ 3a? + 68) ’ MM da’ d* tan 8 and v= = 7a +P) np = a (from (G) and (17)). Substituting the above values for and v in Equation (1), r=%-+v-+4x, and recollect- ing that x =d.tan #, we obtain 2(d* + 0°) st a aby zs w which expresses the distance of P from the front edge of a joint as a fraction of the length of the joint for any value of d e b To comply with condition I we must have Il V RIS wie u : u I Ng=G 7) # ee Se By means of the Differential Calculus we find* x ut Maximum value of = 0:40392 § occurring at d@ = 1.677654, Below this depth < will continually approach the value - reaching it when @ becomes infinite. *Note A, page 385. 38 DESIGN AND CONSTRUCTION OF MASONRY DAMS. It can easily be shown that when d < 4, <> = Thus we see that for the important case of “reservoir full” the effect of the triangle B is to keep the line P within the centre third of the profile. Let us now examine its influence on the line P. Until d= 26, at which depth I 3 the centres of gravity of A and B lie in the same vertical line, we shall have = > . nm 1 Below this depth, ra z Applying the Differential Calculus, we find* se n Minimum value of a= 0.32218; occurring at d= 3.10380. na From this depth down, the value of se will approach z reaching it at an infinite dis- tance. The deviation of P’ outside of the centre third of the profile is so slight as to be of no practical importance. In examining the profiles designed by Rankine, Harlacher and Crugnola (see Tables III., VI., VII.), we find: Profile. Minimum Value of > Ranking, sao & wm w wee ew & £ OF308 Harlachér, « «ow «© & @ @ @ © @ « «= « O3T6 Crugnola, . « w «1 6 Ree 8 we ww # 06325 In Prof. Rankine’s profile we find that even P is allowed to deviate slightly outside . Pc u the given limits, so as to give a minimum value of == 0.308. While it is best to confine P strictly within the centre third of the profile, so as to prevent all possibility of tension at the back face of the dam, a slight deviation from the centre third of the profile by P’ may be permitted. With reference to stability and shearing strength, profile A will evidently be improved by the additional weight B. We conclude, therefore, that by adding a section like B, with any top width, to the triangular profile, we obtain at once a Practical Type No. 1 (see Plate XIV.), which may be employed for any height that gives pressures at the base within the given limits. This type fulfils practically the four given conditions, and the only question which remains to be examined is whether it is the most economical profile which can be found.t To investigate this subject we have calculated Table XVII. for a dam built according to Practical Type No. 1, the top width being assumed as 20 feet. We have also computed Table XVIII. for a theoretical profile having the same top width, and being based simply on the condition that it shall contain the minimum area that will keep the lines P and P’ within its centre third. This profile, which we shall call Theoretical * Note B, page 385. + A profile of this kind was proposed by Prof. Castigliano in the ‘‘ Politecnico” for 1884. PRACTICAL PROFILES. 39 Type No. II, will be found in Plate XV., the triangular profile (No. I) being shown by a dotted line for comparison. By comparing profiles I and II by means of Plate XV. and Tables XVI. and XVIII, we see that the effect of the area added at the top of No. II is twofold: 1st. To reduce the thickness of the profile from that of No. I; 2d. To move the lower part of No. II up-stream from the position of I. As the influence of the wide top of No. II is offset by the reduction of its area lower down, this profile approaches the form of No. I as the depth increases, the corresponding faces becoming nearly parallel. If we examine the batters of the faces of No. II we find that the front face forms a reverse curve, being first concave down-stream and then up-stream, approaching a line parallel with the front face of type I. The back face of No. II is first concave up-stream and then down-stream, approaching rapidly a vertical line. Now before we compare No. II with the Practical Type No. I we must simplify its outlines to obtain a Practical Type No. 2. Plate XVI. shows this profile, and Plate XV. the theoretical type upon which it is based. Table XIX. gives the necessary dimensions, etc. The straight lines and circular curve which have been substituted! for the many changes in the outlines in the theoretical type change that profile but. slightly. To compare the corresponding areas of the Theoretical Types I and IJ, and of the Practical Types 1 and 2, we have considered the area of No. I at any joint as the unit, and have obtained thus the following table: THEORETICAL TYPES, Practica Types, DertH oF Water, IN FEET. I Il 1. 2 Area, Area, Area, Area, On cece encceencavesennsee Oo 0.000 0.000 0.000 ZOsics rine euy Romaewasees I 3.055 3.055 3.055 BOs siainernes 3.4 Re NER AMIE eH I 1.561 1.583 1.579 GO paiauaed aaa nnedets sae I 1.186 1.259 1.196 SOs gis; nierviacheecemoareate grate I 1.064 I.146 1.080 LOO araanse saaeead aw oeeees I 1.027 1.093 1.041 120 iis ceagd ies weeie tae I 1.013 1.065 1.027 TAO hci e an mee meae ister I 1.007 1.047 1.022 TOO. cece nena cc cer ee neene I 1.004 1.037 1,018 TSO. cece rccecenvcossaneces I 1.002 1.029 1.016 QOD. ce cererveecreccncevens I 1.002 I 023 1.015 The above table shows that the differences in the corresponding areas become rapidly less as the depth increases, the profiles being always in the following order as regards smallness of area: I, II, 2, 1. We conclude, therefore, that Practical Type No. 2 is always preferable to No. 1 as regards economy of material. Although the difference between their areas amounts to less than 1 per cent at the base, it is 5.3 per cent at a depth of 60 feet. : The relation between the areas of types I, II, 1 and 2, shown in the table above is general and does not depend upon the top width adopted. For, if we plot. these 4° DESIGN AND CONSTRUCTION OF MASONRY DAMS. profiles to any scale, others, having any desired top width, may be obtained by simply’ changing the scale. The new profiles will always satisfy condition 1. Thus far we have paid no attention to the pressures in the Practical Types 1 and 2, or to their resistance to sliding or shearing. As regards the pressures, Tables XVII. and XIX. show that they increase gradually in these practical types from the top to the base, where they reach the following maxima values for a height of profile of 200 feet: -—————Maxima Pressures. = Reservoir full. Reservoir empty. Tons of 2000 lbs. Tons of 2000 lbs. per sq. ft. per sq. ft. Practical Type No. 1,. . «© . 6. ee 14,35 15.16 Practical Type No. 2,. . . . . 1 . 14.32 14.65 The greatest of these pressures is but slightly in excess of the 14.33 tons per square foot (14 kilos. per square centimetre) sustained by the masonry of the Almanza Dam for over three hundred years without damage. While such pressures cannot be permitted in the upper part of a dam, where they could only result from a dangerous eccentricity of one of the lines of pressure, they can be sustained safely in the lower part, where the lines of pressure will be within the centre third of the profile. There is another important consideration which makes a gradual reduction of pressure from the top to the base of the dam advisable. The strength of the masonry depends, namely, on that of the mortar, whose resistance to crushing increases for a certain time with its age. A dam is weakest, therefore, when just built, its strength diminishing from the base to the top, where the masonry was laid last. With respect to sliding or shearing, Practical Types 1 and 2 will have greater strength than the triangular type No. I, as their areas at any joint are respectively greater than that of the latter type, and hence give smaller values for f in the formula (F) (page 19). We have already demonstrated that the triangular type No. I has ample strength against sliding or shearing, and types 1 and 2 are still safer in this respect, as shown above. When the limit of pressure has been reached in any of the types I, IJ, 1 or 2, more batter must be given to the faces by applying Equations (4) to (7). In this case the areas of the profiles will be greater than if the above-mentioned types had been continued to a corresponding depth, and consequently their resistance to sliding or shearing will also be increased. It follows, therefore, that so long as the lines of pressure are kept within the centre third of the profile, a dam will always have ample strength against sliding or shearing. From what has been shown regarding the strength of the Practical Types 1 and 2 we can draw the general conclusion, that the profile of a dam which is to be built of ordinary rubble-masonry, weighing about 145 lbs. per cubic foot, can safely be based upon the first general condition given at the commencement of this chapter, provided its height does not exceed 200 feet. The Furens Dam, which surpasses all other reservoir walls in height, has a maximum elevation of 194 feet above its foundation. Higher dams may be built in the future, but will probably be exceptional. “Condition 2, which limits the pressure in the masonry, will, therefore, but rarely have to be considered. As regards condition 3, we have shown that it is necessarily fulfilled by our satisfying condition 1. The facts stated above make the design of an ordinary masonry dam, having a height PRACTICAL PROFILES. 41 of less than 200 feet, a very simple matter. Standard profiles, similar to Practical Types 1 and 2, can be drawn for different weights of masonry, and can be used for lesser heights than their own (which is assumed as 200 feet) by simply changing the scale of the drawing. Tables giving the dimensions and strength of the derived profiles can be readily obtained from Standard Tables like Nos. XVII. and XIX, by the simple process of division explained in those tables. It can easily be proved that the derived profiles will satisfy the same conditions as the original types. In establishing practical profiles for various heights we can adopt cither Type No. 1 or No. 2; but as the latter satisfies rigidly the four given conditions, and at the same time contains practically the minimum area consistent with these conditions, and with the necessity for simple outlines, it is to be preferred. Although this type might be used until a pressure of about 14 tons per square foot were reached, we shall assume for our practical profiles a limiting pressure of 8 kilos. per square centimetre (8.19 tons of 2000 Ibs. per square foot) at the front face, and 10 kilos. per square centimetre (10.24 tons of 2000 lbs. per square foot) at the back face, in order to keep within the limits usually recommended by engineers. The specific gravity of the masonry will be assumed as 2}. From Practical Type No. 2 we obtain, by the simple method explained above : Practical Profile No. 1 (Plate XVII., Table XX.)—Top width, 5 feet; height, 50 feet. Practical Profile No. 2 (Plate XVIII., Table XXI.)\—Top width, 10 feet; height, 100 feet. The third practical profile which we shall give will be based upon Theoretical Profile No. 5 (see Plate X. and Table XII.). To make this profile a practical design we have only to simplify its outlines. Small changes in this respect will have very little influence upon the strength of the profile. We have adopted a curved outline for the front face and a few straight lines for the back face, obtaining thus: Practical Profile No. 3 (Plate XIX., Table XXII.)*—Top width, 18.74 feet ; height, 200 feet. This- profile is the last illustration we shall give of the method we have advocated in this book, which consists in obtaining first a correct theoretical form, and then in simplifying its outlines. While we have required the theoretical profiles to fulfil rigidly the given conditions, it would evidently be a useless refinement to insist on the same accuracy for the practical design. As the theory of masonry dams has to be based upon hypotheses which are only approximately correct, we can permit the practical profiles to differ slightly from the given conditions. How trifling the effect of changing the outlines of theoretical profile No. 5 has been will be seen by comparing Table XII. with Table XXII. Thus, the line of pressure P (reservoir full) remains within the centre third of the profile, and the line of pressure P’ (reservoir empty) is only at two joints a little outside of this limit, viz.: At a depth of 100 feet, 0.332 instead of 0.333 At a depth of 110 feet, 0.330 instead of 0.333 * The results given in this table have been checked by the graphic process, as explained in Note C, page 386 (see Plate XX.). 42 DLSIGN AND CONSTRUCTION OF MASONRY DAMS. A greater eccentricity than this will be found in the types of Rankine and Harlacher (sce page 38). The maxima pressures at some of the joints are slightly in excess of the fixed limits, the greatest difference, however, amounting to less than 3 per cent. Practical Profile No..3 has been based on the conditions given by Rankine, the maxima pressures at the up-stream and down-stream faces being limited, respectively, to about 1o and 8 tons per square foot. In recent constructions much higher limits of safe pressure have been assumed. We have stated on page 41 that Practical Type II is to be preferred to Type I, as it contains practically the smallest area satisfying the given conditions. As far as simplicity of design is concerned, Type I will be preferred by many engineers to Type IH. The difference between the areas of these two types is not very great (see Tables XVII and XIX), and when we consider how little is known of the actual distribution of pressures in a mass of masonry, it may not be advisable to insist on adopting rigidly the type that has theoretically the minimum area. We cannot imagine a simpler profile than that given by Practical Type No. I. Although engineers generally give some batter to the up-stream face of the dam, the author knows of no theoretical or practical reason why the up-stream face of a dam should not be made vertical until the adopted limit of safe pressure is reached. At a depth of 200 feet this maximum pressure in Practical Type No. I is only about 15 tons per square foot, a pres- sure that can be safely supported by good masonry. The down-stream face in Practical Type No. I is built on one batter from the base to the vertical face at the top. The angle made by the battered and vertical parts of the down-stream face should be rounded off by a curve as shown in our Practical Profiles 1 and 2. On Plate A we have compared our Practical Type No. I with the profile-types proposed by the different engineers mentioned in Chapter J. As these types are not based exactly on the same data, a fairer comparison of their respective methods can be obtained by tke following table, in which we have also included the profile designed by Professor Harlacher for the proposed Komatau Dam. COMPARISON OF PROFILE-TYPES. Maxima . ile pe ey AREAS IN SQuaRE Metres—Derrnus oF WaTER, i wily, | Cree || Cenamnettes, ype. in 6 of Metres. ] a etres, asonry Re — wee 7" 15 20 25 30 35 40 45 50 Full. | Empty. ctres.| Metres. | Metres. | Metres. | Metres. | Metres | Metres | Vetres.| Metres. De Sazilly......-. 5.09 2.0°0 | 5.99 | 6.00 | 50.80} 86. 78)149.4°] 213. 3°] 308. 2.1143 ~.36/594.6 |7 9.84]1027.89 Delocre........-- 5.00 2.000 | §.99 | 5.00 | 56.33) 91.94/144.45]215 .08]307. 31|428. 71/579. 26 767.65) 995.30 Rankine.......... 5-7L 2.000 | 7.55 | 9.80 | 70.34/118.48]176.97/249 .08)337.56)446.02|579.2¢|742.68 943-54 Kranths ons ccwcaes 5.00 2.300 | 5.77 | 6.00 | 55.69] 94.24/146.33/216.83)/312. 10/439. 81/618. 11/838. 11y1099.81 Harlacher........ 4.00 2.200 | 6.73 | 5.75 | 44-35] 79.85)132.95]205.75]300.40/418.92] .... | .... 28s Crugnola. ........ 4-75 2.300 | 7.72 | 8.27 | 51.29] 87.84]140.73|214.02/309.07/427.27/578.27 761.77| 996.11 Prac. Type, No.f | 5:00 2.333 |11-49 |12-13 | 51-85) 92.75|/150.00/223.73)3 3.70)420.03) 4 .70)68r.95] 837.35 & The areas compared are entirely below the highest water-surface assumed for the respective types, the parts of the profiles above the water-surface being omitted. The ‘maxima pressures given occur within a limit of 50 metres depth of water. PLATE A. COMPARISON OF PROFILE TYPES (,S0°F9T) 1 S19}9TA OF a —- - _—" _ . TEE y Ty Z UY ee x Eh UY ~~ GZ, SR Yi ‘a Practical Type No, 1 Suzilly’s Type ———— Prof. Rankine’s Type | Krantz’s aioe DSlGNTE’S 4 —-—-—Crugnola's ( Scale of Meters T GET Eee rer hg PRACTICAL PROFILES. 45 No attention was paid in designing the profiles given in the above table to the pressure against a dam that might result from the expansion of ice, nor to an upward water pressure against the base of the dam. In some profiles designed in recent years * these two forces have been taken into account. There is no positive information available about either of these forces. Ice, when confined as between bridge piers, may exert a great pressure in expanding, but in the case of a reservoir, which usually has sloping banks, it docs not seem as though the ice could exert any great thrust against a dam. As regards an upward water pressure, due to the head of water in the reservoir, some attention should be paid to this force in the case of very scamy foundations, but in most cases this force will be exerted only on a very small area of the base of the dam. * Quaker Bridge Dam (plan of Board of Experts), Wachusctt Dam, Crosa River Dam, and Croton Falls Dam, q.v. 46 DESIGN AND CONSTRUCTION OF MASONRY DAMS. CHAPTER VI. CONSTRUCTION. Preliminary Investigations.—The general location of a storage reservoir in a valley is determined by a consideration of the available watershed and by a topographical survey to ascer- tain the quantity of water that can be stored. The best site for a dam must be found by exploring the valley by means of diamond-drill and wash borings, trenches, and test-pits. The narrowest place of the valley is not necessarily the best location for the dam. The nearness of the bed rock to the surface and its character are very important factors in selecting the site where the dam can be built at the least cost. In studying the results obtained by the test borings and pits it is advisable to have the assistance of a good geologist, who may notice features of the rock formation that might escape the attention of the engineer. Plans.—After the location of the dam has been determined, the engineer proceeds to pre- pare the plans for construction. We shall assume that a masonry dam has been decided upon, The first point to be considered is the alignment of the center-line of the dam, which may be a straight line across the valley, a broken line, or a curve. A masonry dam cf considerable height must be founded on solid rock. Where the depth to bed rock varies considerably across the valley, a location on a broken line giving the least excavation to rock may be much more economical than a straight alignment, even though the length of the dam be somewhat increased. When the valley which is to be closed by a reservoir wall is narrow, the idea naturally sug- gests itself to curve the plan of the dam so as to make it form a horizontal arch, convex up-stream, transmitting thus the thrust of the water to the unyiclding sides of the valley. That under such circumstances a wall may resist the water pressure, when unable to do so merely by its weight, is proved by the Zola and Bear Valley dams. The effect of curving the plan of a dam has been investigated mathematically by the French engineers Delocre and Pelletreau (see their memoirs in the Annales des Ponts ct Chaussées for 1866 and 1876-1877); by Silas H. Woodward, Assoc. M. Am. Soc. C. E., in his paper on “ Analysis of Stresses in Lake Cheesman Dam” (Trans. Am. Soc. C. E. for 1904), and recently, in connec- tion with the design of the Pathfinder and Shoshone dams, by Edgar T. Wheeler, M. Am. Soc. C. E., under the direction of George Y. Wisner, Consulting Engineer of the Reclamation Service of the United States Geological Survey (see report made in May 1905 by Mr. Wisner to F. H. Newell, M. Am. Soc. C.E., Chief Engineer of the Reclamation Service, which is published in full in Engineering News for August 10, 1905). Two questions arise in connection with a curved dam: ist. Under what circumstances will a curved dam resist as an arch? 2d. When it does act in this manner, can the profile be reduced irom what would be required if the plan were straight? With reference to the first of the above questions, it is known that a stone structure will not act as an arch if its thickness at the cre wn is too great with reference to the radius. The limit- CONSTRUCTION. 47 ing value of this relation cannot be determined in the present state of our knowledge of the sta- bility of arches, and it remains therefore a matter of judgment. M. Delocre thinks that a curved dam will act as an arch if its thickness does not exceed one third of the radius of its up-stream (convex) side. M. Pellctreau places the limiting value of the thickness at one half of this radius. When a dam does act as an arch, it is evident that it can only transmit the watcr-pressure to the sides of the valley, and that its own weight must still be borne by the foundation. To investigate the horizontal thrust to which the masonry will be subjected under these circumstances, we will first imagine the dam to form part of a vertical shaft or well having to sustain the pressure of water only cn its outer (convex) surface. Such a structure ought evidently to have a circular plan, as it is subjected to a similar force all round. Suppose the well to be divided into horizontal courses, cach of them forming a ring com- posed of a number of voussoirs. As the only force acting on each ring in a horizontal direction is the water-pressure, it follows that the line of pressure (resistance) in cach ring will form a circle passing through the centres of the voussoirs. “The thrust round a circular ring under an uniform normal pressure is the product of the pressure on an unit of circumference by the radius.” * It may therefore be expressed by the following formula: T= pr, (19) in which T =the uniform thrust in the circular ring; p=the pressure per unit of length of the ring; v=the radius of the ring’s outer surface. Now if we remove part of the well and replace it by the practically rigid sides of the valley, we will have the case of a curved dam. The conditions in the masonry will remain unchanged, and the horizontal thrust in any course may be calculated by the above formula. To find the maximum pressure exerted by this thrust on the masonry, we must know the position of the line of pressure. Pelletreau has assumed it to remain in the centre of each course, as in the case of a circular ring, the thrust being uniformly distributed on the masonry. Delocre places the position of the circular line of pressure on the up-stream limit of the centre longitudinal third of the course, and estimates, therefore, the maximum pressure on the masonry as twice the average pressure (formula B, page 14). When a curved dam is subjected to the water-pressure it will yicld slightly, owing to the clas- ticity of the masonry; but the sides of the valley will remain practically unchanged. It follows, therefore, that although we may calculate the horizontal thrust in any course by formula (19), as in the case of the circular well, the position of the line of pressure will be somewhat modhfied, approaching at the centre of the valley the up-stream face. The, maximum pressure on the masonry will be greater than the average pressure, although probably not so large as assumed by M. Delocre. It may be shown theoretically that, in the case of a narrow valley, a profile of less area may be adopted for a curved dam than for one whose plan is straight. M. Delocre comes to the con- clusion that in cither case, unless the height of the wall exceeds 84.85 metres (280.4 feet), its * Professor Rankine’s “Applied Mechanics,” page 184. 48 DESIGN AND CONSTRUCTION OF MASONRY DAMS. thickness at any given depth need never be greater than the width of the valley at that point. There is, however so much uncertainty involved in the assumptions made in the mathematics of curved dams, that the best way to proceed in practice is to design the profile sufficiently strong to enable the wall to resist the water-pressure simply by its weight, and to curve the plan as an additional safeguard whenever the locality makes it advisable. This method is recommended by Rankine, Krantz, and other eminent engineers. It is evident that the advantage to be derived from curving the plan of a dam is confined to narrow valleys; for in the case of those of considerable width, requiring a large radius of curva- ture. the pressures in the masonry resulting from the dam’s acting as an arch are considerably in excess of what they would be if each section of the wall resisted simply by its weight. Should such a long dam not act as an arch, then the curving of the plan, by adding length to the wall, would involve a waste of material. Aside, however, from any question of strength, the curving of the plan of a dam has the advantage of tending to prevent cracks in the masonry due to variations in temperature, which are almost sure to occur in straight dams. As soon as the engineer has decided whether the dam is to have a straight or a curved plan, he can proceed to design the profile, which is to be determined by the principles discussed in the preceding chapters. In designing the dam he will have to decide upon the details how water is to be drawn from the reservoir and how the waste-water is to be discharged. Protective Works.—Before the foundation trench for the dam can be excavated across the river-bed, the river must be diverted or coffer-dams must be constructed in the river to enclose a certain part of the work. In diverting the river a temporary dam is constructed across its bed, at a convenient distance above the site of the masonry dam, and the river is either turned into some lateral valley by means of a tunnel or a cut, or it is confined in a flume built along the side of the valley from the diverting dam mentioned above to a second temporary dam built some distance below the permanent dam, where the river is turned into its old channel. As the foundation excavation is made the flume must be supported by trestles. When the masonry has been carried up to the bottom of the flume, iron pipes are usually embedded in the dam and replace the flume through the dam, being connected to it at the up-stream and down-stream faces. The scour or outlet pipes of the dam may be used for this purpose or special pipes may be provided which are afterwards filled with concrete. If the river be too large to be confined in a flume, a temporary channel may be excavated for it on one side of the valley, and lined, if necessary, with masonry walls. In designing the flume or temporary channel, provision is usually only made, on account of the expense involved, for ordinary floods and not for extraordinary discharges of the river which are allowed to overflow the work. When a river cannot be diverted and is too large to be confined in a flume or temporary channel, the dam will have to be constructed by means of coffer-dams. Two or more will be required. The dam is first brought up in these coffer-dams to the ordinary water line of the river, As the masonry is built higher a breach is left to take care of the river. This breach is finally closed at a time of low water, the river being passed through the dam by the outlet-pipes. Foundation Excavation.—On account of the great width that must be given to the base of a masonry dam of considerable height, the foundation excavation must be made in “open trench.” When bed-rock is reached, the excavation is continued a certain depth (3 to 5 feet), even if the rock is perfectly solid, in order to lock the foundation into the rock and to make it impossible for the dam to slide. Should the bed-rock be found to be too soft to bear the pres- CONSTRUCTION. 49 sure it is to bear, or full of seams, the excavaticn must be continued until a stratum of suffi- ciently solid and water-tight rock has been uncovered. In order to discover seams in the rock that may permit water to leak under the foundation, the excavation to rock should be made for some distance above the up-stream face. A number cf test holes should, also, be drilled in the foun- daticn rock to search for seams. This precauticn is especially necessary if the foundation is on limestone, in which occasionally cavities cccur. In making the excavation cne cr mcre cableways for handling the material are a great convenience. They are usually stretched across the valley over the trench from towers erected on the hillsides, and are used, also, in laying the masonry. Masonry.—Before any masonry is laid, the rock bottom should be swept clean and washed by water under pressure. All seams must be closed by concrete or grout. Springs that are encountered in the foundation should be drained to some central point where the water is pumped. If the spring is under considerable pressure the water can be con- fined in a vertical pipe that is surrounded by masonry and is eventually filled with gvout. The masonry of which the dam is built may be cut stone, rubble, or concrete, or a combina- tion of these kinds of masonry. As far as strength is concerned cut stone would be the best class of masonry for bui:ding a dam, but, on account cf its great cost, it is only used at the faces of the dam and for the p:rapet and ornamental work at the top. The inner part of the dam is usually built of rubble, concrete, or cyclopean masonry, which is a combination of rubble and concrete, large stones, just as they come from the quarry, being embedded in and surrounded by concrete. In laying the rubble the stones should break joints in all directions. Horizontal courses should be avoided and the masonry should be made homogeneous so as to form as nearly as possible a monolith. The rubble or concrete should be laid with special care at the faces so as to give the dam a gocd appearance. In many cases the down-stream face and that part of the up-stream face that is above the usual water line of the reservoir is made of cut stone or concrete blocks, which are laid normal to the faces and not horizontal. It is not advisable to lay any masonry in a dam in very cold weather, but if it must be done the usual precautions are to be taken. The water and sand should be heated and some salt added to the mortar. The stones should be cleaned by a steam jet, and at night the freshly laid masonry should be protected by canvas covers, etc. Drainage System.—However carefully the masonry be laid, a certain amount of leakage will always take place in a dam. This loss of water, which in a well-constructed reservoir wall shows itsef only as a dampness on the down-stream face, generally disappears in course of time. As some water is likely to percolate into the masonry, a system of vertical drainage-pipes has been placed in some recent German dams and connected with a drainage-gallery, to discharge all the water that may enter the masonry. The vertical drainage pipes, which are about 4 inches in diameter, are usually placed with open joints in small shafts built in the masonry, about 6 feet from the up-stream face and about 8 feet apart. To make the seepage as small as possible the up-stream face of the dam is sometimes coated with a mixture of asphalt and coal tar, and a tight embankment is carried up, to almost half the height of the dam. In the Vyrnwy Dam, in Wales, a system of drains is constructed in the foundation to relieve the base of the dam from the upward pressure that would occur if water leaked under the dam. 59 DESIGN AND CONSTRUCTION OF MASONRY DAMS. It is doubtful whether a system of drainage placed in the dam or its foundation is advan- tageous, except in special cases. By giving a free outlet to the seepage water such a system encourages leakage. Most engineers prefer to construct dams as tight as possible so as to offer the greatest resistance to seepage. Water that passes through a thick masonry dam and only shows itself as a moist spot on the down-stream side can scarcely be considered to cause an upward pressure in the masonry. On the contrary, in passing through the pores of the stones and mortar it increases the weight of the masonry and consequently the stability of the dam. Backfilling.—As the masonry is carried up, the space between the dam and the slopes of the foundation trench should be carefully filled with suitable material. On the up-stream side this refilling should be placed with all the precautions taken in constructing tight earth dams. The refilling should be sprinkled with water and rolled so as to compact it as much as possible, in order to prevent the water in the reservoir from percolating to the base of the dam. Usually the refilling on both sides of the dam is not carried up much above the former river- bed. In some dams built in Germany, however, according to the designs of Prof. Otto Intze, a tight earthen embankment is constructed on the up-stream side of the dam to half its height. Whether this is an advantage or not is a question. If the earth bank becomes saturated, it will cause a greater pressure against the dam than the water alone. Waste-weir.—Unless a dam be designed to pass the waste-water from the reservoir over its crest, a special overflow-weir must be constructed. This weir may be located in the center of the dam, at either end or some distance from the dam, at some place where the waste-water may discharge into a lateral valley or into a tunnel driven through the hillside. The crest of the waste-weir must be placed at a sufficient depth below the top of the dam (usu- ally 5 to 20 feet) to prevent the water in the reservoir from flowing over the dam. The length of the waste-weir is to be determined by the usual hydraulic formule (see page 226). The profile adopted for the waste-weir is usually given a larger section than that adopted for the main dam. Its down-stream face is either stepped or curved. Examples of both kinds are given in the descrip- tions of dams contained in this book. Gate-houses.—The outlet from the reservoir is usually made through two iron or steel pipes, which are embedded in the masonry at about the level of the former river-bed. The flow into these pipes is usually controlled by sluice-gates, placed in a gate-house, built on the up-stream side of the dam, and stop-cocks are usually, also, provided for the pipes in a vault built at the down- stream face of the dam. Occasionally local conditions make it advisable to construct the outlet from the reservoir at some distance from the dam. The gate-house consists usually of a substructure containing the water-chambers, sluice-gates, etc., and of a superstructure that protects the hoisting machinery of the sluice-gates. The floor of the gate-house is usually placed at the level of the crest of the dam. The substructure is divided by a partition wall into two water-chambers, one for each outlet- pipe. Each chamber has generally three inlet openings, protected by iron or brass screens, viz., one near the surface of the reservoir, one near its bottom, and the third about half-way between the other two. The screens slide in grooves cut in the masonry, and back of the screens a second set of grooves should be provided for stop-planks by means of which the gate-chambers can be separated from the reservoir whenever repairs may be required. Each of the water-chambers has a cross-wall in which openings are constructed that may be closed or opened by sluice-gates operated from the floor of the gate-houses. a a CONSTRUCTION. 51 Sluice-gates and Stop-cock Valves.—The first sluice-gates used were made of wooden logs roughly squared and bolted together. These gates were raised by chains and winches or by having racks attached, which were moved by pinions, held in standards and revolved by hand- wheels. While wooden sluice-gates of improved design are still used, cast iron has replaced wood in all important sluice-gates. Ribs are cast on the back of the gate in order to give it sufficient strength to resist the water pressure (Fig. 22). The gate slides usually in a cast-iron frame which is bolted to the masonry, the joint between the frame and the stonework being made tight by means of sulphur, lead, or cement. Guides for the gate are attached to the frames. In some modern gates one or more bronze-faced wedges are attached to the bottom of the gate and three or more Fic. 22 Fic. 23. adjustable wedges on each side, which bear against the frame and insure the gate’s closing tightly on its seat. A socket is provided on the back of the gate to reccive the gate-stem or shaft, which is secured by cast-steel cotters. The face of the frame and that of the gate are mounted at all moving or bearing places with bronze, in order to prevent corrosion, and the gate and frame are carefully fitted together by planing and scraping so as to obtain perfectly water-tight joints. A screw-thread is cut at the upper end of the stem and engages with a bronze rotary nut, which is provided with a bearing collar which is securely fastened in a cast-iron standard placed directly above the gate at the point from which the sluice-gate is to be operated. By revolving the nut by hand-power or a motor the gate can be raised or lowered, as the case may be. If desired, the gate can be operated by hydraulic pressure. The simplest way of revolving the nut is by means 52 DESIGN AND CONSTRUCTION OF MASONRY DAMS. of a horizontal hand-whcel which is fastened by one or more keys to the nut (Fig. 25). When more power is desired for operating the gate, sockets for capstan-bars may be attached to the nut, or gearing may be used (Fig. 23). A great deal of power is required for raising a large sluice-gate that is under considerable water pressure. In addition to raising the weight of the gate and its stem, which hang from the operating nut, the friction of the gate on its bearings and between the operating nut and the plates that hold it in place must be overcome. The last-mentioned friction may be very greatly reduced by introducing ball-bearings both above and below the nut collar. Such an arrangement, which has been patented by the Coffin Valve Company of Boston, Massachusetts, is shown in Fig. 23. The balls are made of steel and are placed in “races ” in thin lubricating-oil. The lower ball-race, which has to support the entire weight, of the gate and its stem, is provided with a double set of balls, but only one set is used for the upper race which takes the thrust caused in closing the gates. ] iS i il sm ie Hl maa (ee Fic. 24. FIG. 25. Instead of balls, slightly tapered rollers may be used. Figs. 24 and 25 show such an arrange- ment, which is manufactured by the Coldwell, Wilcox Company of Newburgh, New York. The discharge of a sluice-gate is usually calculated by the formula O=Cca(2 gh), in which Q=quantity in cubic feet per second; c=coefficient determined by experiment, a=area in square feet; h=head in feet; g=the acceleration of gravity. The value of ¢ depends upon how the gate is set. It varies from about 0.60 to 0.80, according to whether the gate is set against a thin wall or against a short sluiceway. In the former case the gate opening may be considered to be an orifice, while in the latter it approaches closely to the condition of a short tube. CONSTRUCTION. 53 Buttressed and Arched Dams.—Thus far we have only considered dams that have uniform profiles, beginning at the top. The question arises whether any saving in masonry might be effected by reducing the area of the profile and strengthening the dam at regular intervals by buttresses or counterforts, or by building a number of isolated piers joined by vertical or inclined arches. As far as the author knows, buttresses have not been used, to the present time, as part of the original plans for masonry dams, although they have been built subsequently in several cases to strengthen dams that were found to have insufficient strength (the Gros Bois Dam, the Gorzente Dam, q.v.). In 1896 a low masonry dam—consisting of piers placed 28 feet apart and joined by curtain walls 4 feet thick, in which a number of I beams were placed—was completed at Princeton, New Jersey, to form Carnegie Lake. In preparing plans for a concrete dam at Ogden, Utah, which was to be 369 feet long and 105 feet high above the foundation, Henry Goldmark, M. Am. Soc. C. E.,* proposed to make the structure consist of a number of piers 16 feet wide, placed 32 feet apart in the clear, which were to support inclined segmental arches. Water-tightness was to be insured by facing the arches with stecl plates. Bids obtained for building this dam according to this plan and also for constructing it as an ordinary “gravity dam” showed a saving of 12 to 15 per cent in favor of the former plan. Thus far this dam has not been built, but the Meer Allum Dam, India (q.v.), and the Belubula Dam (q.v.) in New South Wales, were built on this principle. In a paper on “A Proposed New Type of Masonry Dam” + George L. Dillman, M. Am. Soc. C. E., demonstrated mathematically that a saving in material may be effected by building a dam of piers and arches instead of a uniform wall. In the type proposed by Mr. Dillman the portions between the buttresses are made parabolic in horizontal section, so as to avoid all re-entrant angles. It appears that some saving in material results from such a plan of construction, and a similar style has been generally adopted for reinforced concrete dams (see Chapter XIII), which consists of buttresses, placed 12 to 15 feet apart, joined by a water-tight deck. * “The Power Plant, Pipe-line and Dam of the Pioneer Electric Power Company of Ogden, Utah,” by Henry Goldmark, Trans. Am. Soc. C. E., for December, 1897. { Trans. Am. Soc. C, E. for December, 1902. 54 DESIGN AND CONSTRUCTION OF MASONRY DAMS. CHAPTER. Wii. SPANISH DAMS.* The Almanza Dam4 (Plate XXI.).—The oldest existing masonry dam is that of Almanza, situated in the Spanish province of Albacete, near the town after which it is named. The exact date of its construction is unknown, but it appears from old docu- ments that it was in use prior to 1586. It was founded on rock, and was built of rubble masonry, faced with cut stone except for the upper twenty feet of the front face, which was built of rough ashlar with courses of cut stones at certain intervals. The lower part of the dam, having a height of about 48 feet, is built on a curved plan, convex up-stream, the radius of the back face being. 26.24 metres (86.07 feet). The remaining part of the wall, which was probably constructed at a later period, has a plan whose centre line forms a broken line 292 feet long. The greatest height of the dam is 20.69 metres (67.86 feet). An overflow was formed by excavating the rock on one side of the dam 6.56 feet below its top for a length of about 39 feet. Water is taken for the purpose of irrigation through a gallery 1 metre (3.28 feet) square, which passes through the lower portion of the wall. Above the down-stream end of this outlet-channel a chamber is constructed in the dam, where the bronze gate which regulates the flow of water from the reservoir is operated. To prevent the outlet-gallery from being closed by sediment, the gate is always partially opened during floods. There is another gallery, 1.3 metres (4.26 feet) wide by 1.5 metres (4.92 feet) high, constructed through the dam, and serving for scouring out the deposits of sediment in the reservoir. In our description of the Alicante Dam we shall give a detailed account of the manner in which this operation is performed. x For many years the Almanza reservoir has not been filled, as the water is drawn off twice per annum for irrigation. Although the old Spanish dam described above is not well proportioned, it is an interesting fact that its masonry has sustained safely for three centuries a greater pressure than exists in any other reservoir wall, namely, 14 kilos. per square centimetre (14.33 tons of 2000 lbs. per square foot). The Alicante Dam“ (Plate XXII.).—The highest Spanish dam is that of Alicante,— named also, after a village near its site, the Dam of Tibi. It was built during the years. 1579 to 1594, to supply the arid region of Alicante with water for irrigation. Although the name of its constructor is not known with certainty, there are reasons for ascribing this work to Herreras, the famous architect of the Escurial palace. The gorge of Tibi, which is closed by this dam, is formed entirely of hard cal- careous rocks, the slopes on either side standing almost perpendicular. Its width is only 30 feet at the bottom, and 190 feet at the crown of the dam. * The dams marked 4 are taken from ‘‘ Irrigations du Midi de l'Espagne,” par Maurice Aymard. Paris, 1864. SPANISH DAMS. 55 The river Monegre which flows through this gorge discharges on an average about 50 gallons per second. The length of the Alicante reservoir is 5909 feet, its capacity being about 975,000,000 gallons. The dam is built of rubble masonry faced with large cut stones. Its greatest height on the up-stream side is 41 metres (134.5 feet). The plan of the dam is cur- vilinear, the radius of the up-stream side of the crown being 107.13 metres (351.37 feet). The maximum pressure in the masonry is 11.28 kilos. per square centimetre (11.54 tons of 2000 lbs. per square foot). Water is taken from the reservoir by means of a well, 0.8 metre (2.62 feet) in diameter, which is placed in the dam itself. It is parallel with the up-stream face, and at a distance of about 2 feet from it. Fifty-one pairs of openings connect the well with the reservoir; they are 0.11 metre (0.36 foot) wide by 0.22 metre (0.72 foot) high, and are 0.3 metre (0.98 foot) apart horizontally and 0.41 metre (1.34 feet) vertically. The first pair is 6.97 metres (22.88 feet) below the top of the dam, and the last 2 metres (6.56 feet) above the bottom. By means of this arrangement water can be taken into the well even when much sediment has been deposited in the reservoir. The outlet-well connects at the base of the dam with a horizontal gallery which is parallel with the up-stream face until it reaches the side of the gorge, where it is con- tinued by a small tunnel 0.6 metre (1.97 feet) wide by 1.7 metres (5.58 feet) high. This tunnel curves so as to discharge the water parallel with the axis of the valley. The outlet-gallery is closed at the down-stream face of the dam by a bronze gate, two inches thick, giving an opening when completely raised of 1.77 feet width by 2.30 feet height. Immediately over the gate a small chamber has been cut in the rock, where the gearing for raising the gate is placed. By means of a hand-wheel and gear-wheels engaging a rack, which is attached to the gate, one man can raise or lower the latter with ease, even when the reservoir is full. To prevent incrustations which might obstruct the gate, a small stream of water is always allowed to escape there. It was originally intended to have the outlet-gallery directly across the dam from face to face; but this would have brought it in close proximity to the scouring-gallery, presently to be described. Fears were entertained that such a construction would cause considerable leakage, and the outlet-gallery was therefore turned towards one side of the gorge, as described above. We will now explain the construction and use of the scouring-gallery. Owing to the steep declivity of the beds of most Spanish streams, and to violent storms, large quantities of fine material which has been pulverized by the action of the water are deposited in the storage reservoirs. Unless some means were provided to remove this sediment, it would soon fill these basins completely. In 1843, when the Alicante reser- voir had not been cleaned for fourteen years, a bank of sediment 75 feet high at the dam had been deposited. Since then the reservoir is scoured once in four years, the maximum height of the material deposited during that time being 39 to 52 feet. Long experience has taught the Spaniards the best method of removing these deposits, namely, by means of scouring-galleries. In the Alicante Dam such a gallery is placed in the axis of the valley, crossing the dam in a straight line from face to face. Its 56 DESIGN AND CONSTRUCTION OF MASONRY DAMS. up-stream opening is 1.8 metres (5.9 feet) wide by 2.7 metres (8.86 feet) high. The gallery has this cross-section for the first 2.7 metres (8.86 feet) of its length, and is then suddenly enlarged to a section of*3 metres (9.84 feet) width by 3.3 metres (10.82 feet) height. After this the cross-section is increased gradually, so that it is 4 metres (13.12 feet) wide by 5.85 metres (19.18 feet) high at the down-stream face of the dam. By this increase in the cross-section of the gallery, which takes place in all directions, the material forced out of the reservoir by the water-pressure can expand freely and does not obstruct the channel through the dam. The mouth of the scouring-gallery is closed simply by a timber bulkhead formed as follows: First a vertical row of beams about 1 foot square is placed, their ends projecting into horizontal grooves cut into the solid masonry. The last beam which closes the row is somewhat shorter than the rest, and enters only the lower groove. After the joints between the beams have been calked, a second row of similar timbers are placed directly behind the first row, but are laid horizontal, their ends being secured in vertical grooves in the sides of the gallery. Behind the second row three vertical posts are placed, each of which is firmly held by two inclined braces whose lower ends project into the floor of the gallery. The banks of sediment formed in the reservoir acquire considerable consistency if left undisturbed for a few years. When it is necessary to scour the reservoir it becomes thus possible to remove gradually the timbers at the inlet of the gallery without much danger to the workmen. The timbers of the course next the reservoir are cut, one by one, with the greatest precaution. Should any movement be perceptible in the deposited material the men abandon their work, which will be quickly completed by the water- pressure. Generally, however, the opposite of this takes place. The sediment forms a solid bank in front of the scouring-gallery, and does not move until a hole has been made through it from the top of the dam. The heavy iron bar which is employed for this purpose at the Alicante reservoir is 0.2 feet square, 59 feet long, and weighs about 1100 lbs. It is worked by means of a windlass and pulleys. When a hole has been pierced through the bank of sediment, the scouring action begins, first slowly, but soon gaining a tremendous force. All the sediment, except that in remote parts of the reservoir, is forced through the scouring-gallery, the noise made by this violent action being like that of cannons. Nothing remains for the workmen to do but to shovel the remaining sediment into the current. Sometimes the deposit has become so hard that it must be undermined from the scouring-gallery before a hole is pierced in it by the long bar. The total cost of scouring the reservoir, including the loss of timbers which are cut, amounts to only fifty dollars. Although the method of cleaning the reservoir, which we have described in detail above, seems at first sight rather primitive, yet, on second thought, it will be found to be practical Where such deep deposits are made gates are out of the question, as they would have to be frequently opened to prevent their becoming useless, and would cause thus a considerable loss of water. While the scouring operation as carried on at the Alicante Dam certainly involves danger to the workmen, accidents are very rare. In our description of the Elche Dam we will show how this danger may be avoided. SPANISH DAMS. 57 The Alicante Dam had originally no waste-weir. However, one was built in 1697, as the wall was supposed to have been injured by water flowing over its top. During the freshets of 1792 the depth of the water on top of the dam was 8.2 feet, and it fell in a perfect cascade over the front face. The wall sustained this severe test so. successfully that since then the waste-weir has been closed, no fears whatever being enter- tained of the stability and strength of the dam. The cost of the construction of the great work we have described was borne entirely by the parties interested in the irrigation of Alicante. The Elche Dam*4 (Plate XXIII.).—This reservoir wall is situated on the Rio Vino- lapo, near the town of Elche. Like the dams already described it was founded on rock, and constructed of rubble masonry faced with cut stones. Its maximum height is 23.2 metres (76.1 feet). The Elche reservoir is formed by three walls, which close converging valleys. The principal dam is about 230 feet long, measured on its crest, and is built according to a curved plan, the radius of the back face being 62.6 metres (205.38 feet). No overflow-weir was provided, as perfect confidence was felt in the dam _ being able to withstand the flow of water over its crest without injury. In 1836, however, a considerable breach was made in the wall by water passing over it during a great flood. In many details the Elche Dam resembles that of Alicante. Thus, water is taken from the reservoir by means of a vertical well which was built in the wall near its up-stream face, and has inlet openings at regular intervals. This well terminates in a horizontal gallery, which passes through the dam like that of Alicante, and has its down-stream end closed by a bronze gate operated from a chamber immediately above it. The arrangement of the scouring-gallery, however, is a great improvement on that of the Alicante Dam. Immediately above it a working gallery is placed, which enables laborers to remove the last timbers of the gate which closes the scouring-gallery, with perfect safety. Above the scouring-gate there is a well-hole in the working gallery through which these timbers are pulled out by means of ropes. The Puentes Dam4 (Plate XXIV.).—The construction of the Puentes Dam was considered one of the great achievements of the reigns of Charles III. and Charles IV. of Spain. It was built during the years 1785 to 1791 at the place where the united waters of the Velez, Turrilla and Luchena form the Guadalantin River. After being in use for eleven years it was finally destroyed in 1802. The maximum height of this dam was 50 metres (164 feet); its length measured on the crest was 282 metres (925.3 feet), The whole wall was built of rubble masonry, faced with large cut stones. The outlines of the plan were polygonal, being convex up-stream. The dam was finished with a magnificent parapet, upon which colossal statues of the two kings mentioned above were to have been placed. According to M. Aymard, the maximum pressure in the masonry was 7.93 kilos. per square centimetre (8.12 tons of 2000 lbs. per square foot). An arched scouring-gallery 6.7 metres wide by 7.53 metres high (22 feet by 24.7 feet) was constructed through the dam. At its up-stream end a central pier divided it into two channels, in order to reduce the span of the beams forming the scouring-gate. Water was taken from the reservoir by means of two wells, each of which terminated 58 DESIGN AND CONSTRUCTION OF MASONRY DAMS. m a horizontal gallery 1.65 metres wide by 1.95 metres high (5.4 feet by 6.4 feet). These galleries were placed at different elevations, one being about 100 feet below the top of the dam, and the other near its base at the level of the scouring-gallery. The cross-section of the wells was about 4.2 metres by 2.5 metres (13.8 feet by 8.2 feet), and was rectangular, except that the side nearest the reservoir was formed by a circular arc. Each well had inlet openings, 0.28 metre wide by 0.55 metre high (0.92 foot by 1.80 feet), placed in rows of three, the vertical distance between the openings being 0.83 metre (2.72 feet). According to the original intention the wall was to have been founded entirely on rock. , In the centre of the valley, however, a deep pocket of earth was encountered, and it: was unfortunately decided to build the wall at this place on a pile foundation. The masonry was sunk about 7 feet into the gravel around the piles, which projected above the horizontal caps. As the scouring-gallery and one of the outlet passages discharged in the centre of the valley, where the pocket of soft material was found, the ground at. this place was protected against being washed out by a timber grillage resting on piles which was continued for 131 feet down-stream from the front face of the dam. This timber apron was covered by about 7 feet of masonry, which was protected against the erosion of the water by planks. z The whole pile foundation was built very-securely, and it would have answered all purposes had the depth of the water in the reservoir been less. This is shown by the fact that for eleven years, during which time the depth of the water in the reservoir never exceeded 82 feet, the wall stood perfectly safe. However, on the 30th of April, 1802, the water rose to an elevation of 154 feet above the base of the dam and the foundation gave way. The following account of an eye-witness of the accident is taken from M. Aymard’s book on the “ Irrigation of the Southern Part of Spain”: “About half-past two on the afternoon of the 30th of April, 1802, it was noticed that on the down-stream side of the dam, towards the apron, water of an exceedingly red color was issuing in great quantities in bubbles, extending in the shape of a palm-tree. About three o’clock there was an explosion in the discharge-wells that were built in the dam from top to bottom, and at the same time the water escaping at the down-stream side increased in volume. In a short time a second explosion was heard, and, enveloped by an enormous mass of water, the piles and timbers which formed the pile-work of the foundation and of the apron were forced upwards. “Immediately afterwards a new explosion occurred, and the two big gates that closed the scouring-gallery, and also the intermediate pier, fell in. At the same instant a mountain of water escaped in the form of an arc. It looked frightful, and had a red color, caused either by the mud with which it was charged, or by the reflection of the sun. The volume of water which escaped was so considerable that the reservoir was emptied in the space of one hour. “The dam presents since its rupture the appearance of a bridge, whose abutments are the work still standing on the hillsides, and whose opening is about 56 feet broad. by 108 feet high.* * Mr, Crugnola states that this dam has been lately rebuilt (‘‘ Muri di Sostegno e Traverse dei Serbatoi,” page 275.). SPANISH DAMS. 59 “At the moment of the accident the effective depth of the water was 33.4 metres (109.6 feet). Its surface was 46.80 metres (153.54 feet) above the base of the dam; the lower 13.40 metres (44 feet) being taken up by deposited material.” This fearful accident caused the loss of 608 lives, the destruction of 809 houses, and of property amounting to about 5,500,000 francs (1,045,000 dollars). The cause of the failure of the Puentes Dam is seen clearly in the account we have given above. The wall was not overturned or crushed by the pressure it had to sustain, but failed because it was undermined by the great water-pressure forcing a way through the soft material in the centre of the valley. The rupture of the Puentes Dam teaches the important fact that a high masonry dam, however well proportioned, will only be safe if founded entirely on rock. The Dam del Gasco,4 across the Guadarrama River, was commenced in 1788. Its general dimensions were to have been as follows: Metres, Feet. PPSIB IMs eas oe Soe ee a wR a we a ee 305.12 “ERIGHGSS SP Hase) s @. «ww we wl ae ee ZR 236.22 - BECO: Se ae eee a a ee 4 13.12 Length on crown, . . . . 2 2 6 © © «© + 251 82.35 It was constructed on a straight plan, and was to consist of two walls, 2.8 metres (9.18 feet) thick, connected by cross-walls. The compartments which were thus formed were to have been filled with dry stones imbedded in clay. In 1799, when the dam had already attained a height of 57 metres (187 feet), a heavy rain-storm caused the river to flow over its top. The swelling of the clay, resulting from its becoming wet, forced over part of the front wall, and the dam was never completed. The Dam of the Val de Infierno* (Plate XXV.)—The region around the town of Lorca in the Spanish province of Murcia was formerly supplied with water for irrigation by the reservoir of the Val de Infierno. The masonry dam which forms this reservoir is situated in the gorge of the Rio Luchena, a branch of the Guadalantin River. Owing to the opposition of the land-owners below the site of the dam, who claimed that the scouring of the sediment injured their property, the reservoir has not been used for years, and is now completely ‘filled with deposits. When the river is high it forms a beautiful waterfall over the old dam. The greatest height of this reservoir wall is 35.5 metres (116.5 feet). It was originally intended to build the dam 16 feet higher, ‘but this plan was abandoned as it would have caused the reservoir to include a permeable bank within its limits. The plan of the dam has polygonal outlines, approaching very closely to arcs of circles, convex up-stream. The wall is founded entirely on rock. An arched scouring-gallery, having a uniform height of 4.5 metres (14.8 feet) and a width of 3.75 metres (12.3 feet), except for 16.4 feet from its up-stream end, where its width is only 2.75 metres (9.0 feet), passes through the wall. There are also two outlet-galleries, placed at different levels and arranged like those 60 DESIGN AND CONSTRUCTION OF MASONRY DAMS. of the dams of Alicante and Elche. The vertical wells with which they are connected at the up-stream face of the dam have inlet-openings 0.3 metre wide by 0.5 metre high (0.98 foot by 1.64 feet), placed 3 metres (9.84 feet) apart. This distance is too great. When the deposits close the openings at one level, no water can be drawn out of the reservoir until the water-surface has been raised about ten feet. Part of the up-stream sides of the wells has been torn down in order to facilitate the drawing of water, which makes the dam practically like the primitive one of Almanza, where no wells at all were used. The reservoir of the Val de Infierno was constructed during the years 1785 to 1791. The Nijar Dam4 (Plate XXVI.).—This reservoir wall is situated in a gorge of the Carrizal River in the small village of Nijar, near the town of Almeria. It was designed by the architect Geronimo Ros, and was constructed during the years 1843 to 1850. This dam was founded on rock and built of rubble masonry faced with cut stone. The lower portion of the wall consists of a foundation-mass of masonry, having a width in the direction of the valley of 43.89 metres (144 feet). This masonry extends II metres (36.1 feet) down-stream and 12.29 metres (40.3 feet) up-stream beyond the wall proper. The down-stream face of this foundation-mass is carried up in steps, as shown in Plate XXVI. The maximum height of the dam above the bed of the river is 30.93 metres (101.5 feet). A scouring-gallery, 1 metre wide by 2.19 metres high (3.3 feet by 7.2 feet) passes through the wall. At its up-stream entrance it is only 1.72 metres (5.6 feet) high. It is closed by a gate which is operated from the top of the dam by means of a long rod. Immediately over the gate there is a vertical well, 1 metre in diameter, in the wall, which enables the workmen to examine the gate without being exposed to danger. Water is drawn from the reservoir by means of a vertical well and a horizontal gallery, as in the other dams we have described. The diameter of the well is 2.72 metres (8.9 feet). A winding staircase in the well affords opportunity for closing up the inlet-holes, when necessary ‘for repairs. The overflow-weir consists of two openings, 2.2 metres wide by 1.6 metres high (7.2 feet by 5.2 feet), whose sides are placed 1.6 metres (5.25 feet) below the top of the dam. The capacity of the reservoir is about 5,475,000,000 gallons, but the water-surface is never above half the height of the dam. The Lozoya Dam4 (Plate XXVII.).—About the middle of this century the engineers of the Spanish government constructed a canal, known as that of Isabella II., for supply- ing Madrid with water from the Rio Lozoya. As the natural surface of this river is not sufficiently elevated for this purpose, it was raised by means of a masonry dam 32 metres (105 feet) high, and 72.5 metres (237.8 feet) long on top. This dam consists of a wall of cut stone, 18.66 metres (61.2 feet) thick at the base, backed by rubble masonry, making the total thickness of the dam at its base 39 metres (128 feet). The back face is partially covered by a slope of gravel. The plan of the dam is straight. No galleries pass through the wall; they are driven through the rocky banks of the reservoir. On the right bank there are two galleries; one, 6.82 metres (22.4 feet) below the SPANISH DAMS. 61 crown of the wall, serves to feed the canal, and the other, placed 9.1 metres (29.86 feet) below the same level, is the scouring-gallery, below which the reservoir is allowed to fill up with deposits. On the left of the dam there is an overflow-weir cut in the rock, 8.4 metres (27.6 feet) wide, and 3.35 metres (11 feet) below the top of the wall. The Villar Dam* (Plate XXVIII.).—The Villar reservoir on the river Lozoya was constructed in 1870-1878, to furnish an additional supply of water for Madrid. Mr. José Morer, chief engineer to the Spanish government, designed the reservoir and dam. The work was commenced in 1870 and completed in 1878. The dam is about 170 feet high, and forms a reservoir having a capacity of about 4,400,000,000 gallons. It was built on a curved plan, the radius being 440 feet. The length on top is 546 feet, of which 197 feet are 8’3” lower than the rest in order to form an overflow-weir. The maximum depth of the water below the level of the overflow-weir is 162 feet. Four lateral tunnels serve to discharge the excess of water in case of floods. Two galleries run through the dam at a depth of 143 feet below the level of the overflow. Each gallery has an inlet of nineteen square feet, divided into two compartments, which are closed by sluices. These are operated by means of hydraulic power from a central tower, which is built on the inner side of the dam up to the level of the roadway. With the exception of some cut stone on the crown, the whole dam was built of rubble masonry. The total cost of the reservoir and dam was about $390,000. The two Hijar damst (Plate XXIX.) were built in 1880 on the Martin River, at a distance of about nineteen miles from the city of Hijar, in order to form two large reservoirs for irrigation purposes. The first has a capacity of 6,000,000 cubic metres (1,584,846,000 gallons), supplied from a watershed of 238 square kilometres (92 square miles), and the capacity of the second is 11,000,000 cubic metres (2,905,551,000 gallons), its watershed con- taining 43 square kilometres (17 square miles). Each reservoir has a masonry dam whose general dimensions are: Metres. Feet. Ihengthon. tOpyur eae ce ae ee a 72 236.22 eightys: 2 a aw eS Soe wR Sa Se ae HB 141.07 Width at ‘top; @.04 @ s0 @ so 8 4 Se @ ce 5 16.40 “« — “ g metres below top, . ..... 5.2 17.06 00 SO DaSEy Bo Rig es GRE a 146.98 Square Metres. Square Feet. Area of profile,. 2. 2. 1 1 6 6 6 ee ee 785.45 8,453.8 The back face of the profile is formed of a vertical line to a depth of 25 metres (82.02 feet), from which point it is continued bya circular curve, whose versed-sine at the base is 6.50 metres (21.33 feet). The front face is formed of a sloping line to a depth of 9 metres * Proc. Inst. C. E., vol. 71, page 379. + ‘‘ Bacini d’irrigazione,” per G. Torricelli. 62 DESIGN AND CONSTRUCTION OF MASONRY DAMS. (29.53 feet), and then of a series of steps 2 metres (6.56 feet) high, and having an average width of 1.50 metres (4.92 feet). The outer corners of these steps are located in a circular arc, concave down-stream. The maximum pressures on the masonry are: Kilos. per Tons of 2000 Ibs. sq. centimetre. per sq. foot. Reservoir full, . . 2. 2. 2. 6 ew 5 ee Resetvoit GMiGty; « « e & « -« & & 5.86 5-99 Both of the Hijar dams are founded on rock, and are built circular in plan, the radius being 64 metres (210 feet). FRENCH DAMS. 63 CHAPTER. ‘VIII. FRENCH DAMS.* THE masonry dams built in France prior to the publication of M. de Sazilly’s “ Profile of Equal Resistance” in the “ Annales des Ponts et Chaussées” for 1853 have less extrava- gant profiles then the old Spanish dams, but show, nevertheless, an utter absence of any rational theory regarding the proper method of designing a masonry dam. The difference of opinion held formerly by engineers as to which side of the profile ought to have the greater horizontal projection is shown in the following profiles, which we have taken from M. Krantz’s “Study on Reservoir Walls :’+ Lampy Dam (Plate XXX.), built in 1776-1782, on the canal of the South. Vioreau “ (Plate XXXI.), “ “ 1833-1838, on the canal from Nantes to Brest. Bosmelea“’ (Plate XXXII), * “ 1833-1838. Glomel “ (Plate XXXIII.), “ “ 1833-1838, on the canal from Nantes to Brest. The Gros-Bois Dam” (Plate XXXIV.) was constructed in 1830-1838 on the Brenne River to form a reservoir for feeding the canal of Bourgogne. Its principal dimen- sions are: Metres. Feet. Leneth Of 16); oa « « «4s » & «© & « S§q00 1804.6 Height above river-bed, . . . . 2... . © 22.30 73.2 “foundation, . . . »« .. . 28.30 92.9 Widthvat'top,. % 4 6 *# «#6 Ba & 4 6.50 21.32 a PAS IDASE:. ae ap ae Ga MS Se we POO 45.9 The overflow-weir is 10 metres (32.81 feet) long and 3 metres (9.84 feet) below the top of the wall. The foundation upon which this dam was buiit consists of argillaceous rock possessing little hardness. When the wall had attained a height of only 4 metres (13.12 feet), a serious leak occurred through the foundation. Some lime was thrown near the crevices produced by the leak, but did not stop the loss of water. The reservoir had, therefore, to be emptied, and the crevices closed with masonry. In 1837 the tunnel which had been used as a waste-weir during the construction was closed, and the water allowed to fill the reservoir. When it had reached a depth of 17.45 metres (57.25 feet) its pressure produced a fissure at the intersection of the dam with the tower of the gate-house. It was noticed that the wall deflected a few centimetres down-stream under this pressure, and, upon the reservoir being emptied, returned almost to its original position. This fact proves that masonry has considerable elasticity. * The dams marked T are taken from ‘‘ Bacini d'Irrigazione,” per G. Torricelli. Roma, 1885. + Paris, 1870. 64 DESIGN AND CONSTRUCTION OF MASONRY DAMS. In addition to this deflection, it was soon noticed that the wall had slid 0.045 metre (0.15 foot) down-stream. To arrest this motion the dam was reinforced in 1842 by seven counterforts, each being 4 metres (13.12 feet) thick on top and 11.30 metres (37.08 feet) at the base, projecting 8 metres (26.25 feet) from the front face. As fissures, however, were still noticed in the foundation, two more counterforts were built, and stopped all further trouble. The Tillot Dam™ is 13 metres (42.65 feet) high above the bed of the river, and 20 metres (65.62 feet) from the foundation. It has both faces vertical, and is 5.45 metres (17.88 feet) thick. The Chazilly Dam™ is situated in the Sabine Valley near Chazilly. It is 22.50 metres (73.80 feet) high, and 536 metres (1758.62 feet) long on top. Its thickness is 4.08 metres (13.39 feet) on top, and 16.20 metres (53.15 feet) at the base. It was built according to the profile of the Gros-Bois Dam (see Plate XXXIV.). The Zola Dam (Plate XXXV.) was built about the year 1843 to form a reservoir for supplying the city of Aix (Provence) with water. It is named after M. Zola, the engineer who projected its construction but died before the plans were matured. The general dimensions of this dam are as follows: Metres. Feet. Length on top, % « 4 a «© *# «9 w@ 2 & “6255 205.00 8 aie Wasenr a . Gait: al Ayetantemey yaoi dee ok 7.0 22.96 Height above foundation, . . . .. . . 36.5 119.76 Width at top, .« 2 © 6 © © © w 8 * 4 5.8 19.02 s FE DASE}... 360 Jd!) tee Gee cae Ae a eee BS 41.82 Square Metres. Square Feet. Cross-section of wall, . . . . 2. . . . . 338.62 3644.6 The wall is surmounted by a parapet 1.20 metres (3.94 feet) high. The Zola Dam is built of rubble masonry and made circular in plan, the radius at the crown being 158 feet. This dam is the only one known to the writer which is unable to resist the thrust of the water by its weight alone, and owes, therefore, its stability solely to its acting as a horizontal arch abutting against the sides of the valley. Assuming the specific gravity of the masonry as 2.2, we find that when the reservoir is full the resultant pressure at the base lies 3.5 metres (11.48 feet) outside the wall. At 9 metres (29.52 feet) height it would be 2.50 metres (8.20 feet) cutside of the front face. Ata height of Ig metres (62.32 feet) the resultant would be 2.75 metres (9.02 feet) inside of the wall, causing a maximum pressure on the masonry of 7.93 kilos. per square centimetre (8.12 tons of 2000 lbs. per square foot). We have taken the above description from the memoir on the Verdon Dam by M. Tournadre, published in the “ Annales des Ponts et Chaussées” for 1872 (Ist semestre). The Dam of Settons was built in 1855-58 to improve the navigation of the Yonne River. It is 21 metres (68.89 feet) high above the foundation, 271 metres (889.03 feet) long on the crest, and was originally 4.30 metres (14.10 feet) wide on top. The down- stream slope is on a batter of 1:33; the up-stream slope was originally vertical for a certain distance and then had two offsets of 1 metre each. In 1899 the thickness of FRENCH DAMS. 65 the dam was increased by 5.28 metres (17.31 feet) by building a guard-wall on the up-stream side of the dam for its whole height. Vertical wells of a horseshoe section were constructed in this guard-wall to intercept leakage through the masonry, and were connected with a drain. The Furens Dam (Plate XX XVI.).—This dam is also known as that of the “Gouffre d’Enfer,” the name of the gorge which it closes; also as the dam of Rochetaillée, the name of a village near its site; and as the dam of Saint-Etienne. In 1858 the French government decided to construct an immense reservoir in the valley of the Furens River in order to protect the town of Saint-Etienne from inundations. The total cost of the work was estimated at $298,300, of which amount the town of Saint- Etienne agreed to pay $190,000 for the privilege of using part of the reservoir for storing water. The mean annual flow of the Furens River is about 130 gallons per second, but in dry seasons it amounts to only 21 to 26 gallons per second. In 1849 the town of Saint- Etienne was inundated, owing to a great rise of the Furens River, caused by the bursting of a water-spout. According to the calculations of the French engineers the discharge of the Furens at that time must have amounted to about 34,600 gallons per second. The reservoir was designed to prevent inundations even in case of a similar maximum discharge. The drainage area of the Furens above the reservoir site is 9.65 square miles, and the mean annual rainfall 39.4 inches. The engineers who designed and constructed the Furens Dam and reservoir are: M. Greeff, the Chief Engineer of the Département of the Loire; M. Delocre, who made the theoretical studies of the best form of profile; and M. Montgolfier, who had charge of the construction. M. Conte-Grandchamps assisted in the preliminary studies, but was promoted to another position before the masonry was commenced. The greatest depth of water in the reservoir is 50 metres (164 feet), the total storage capacity being 1,600,000 cubic metres (422,625,000 gallons). Of this, however, the town of Saint-Etienne is only allowed to utilize 1,200,000 cubic metres (316,969,000 gallons), corre- sponding to a depth of water of 44.5 metres at the dam. The remaining 400,000 cubic metres (105,656,000) gallons of storage are reserved for preventing inundations. The outlet from the reservoir consists of two cast-iron pipes, 0.40 metre (1.31 feet) in diameter, which pass through a lateral tunnel. In constructing a dam exceeding in height all that were then existing, it is not aston- ishing that the engineers in charge of the work adopted out of precaution the low limit of pressure of 64 kilos. per square centimetre (6.64 tons of 2000 lbs. per square foot), although they knew that some of the old Spanish dams sustain much greater stresses. As the gorge which was to be closed was very narrow, it was decided to make the plan of the dam curvilinear, the radius being 252.50 metres (828.38 feet). The chord at the crown of the wall is 100 metres (328.07 feet), having a versed-sine of 5 metres (16.4 feet). This is the first French dam that was built curvilinear in plan. The profile was based upon the type proposed by M. Delocre, which is shown in Plate IJ.; but curvilinear outlines were adopted in order to produce a more pleasing appearance. The thickness at the top of the dam was increased on account of the danger 66 DESIGN AND CONSTRUCTION OF MASONRY DAMS. from floating masses of ice; but at the bottom the width of the profile is slightly less than in Delocre’s type. The greatest height of the dam above the foundation is 56 metres (183.72 feet) on the down-stream side, but up-stream it is only 52 metres (170.6 feet). . Great pains were taken in all the details of construction. Before excavating the foundations a new, permanent channel was made for the Furens, and two lateral tunnels were also excavated to serve subsequently for the outlet-pipes. By these means, and a coffer-dam, the foundation was kept perfectly dry. The rock on which the dam was built was mica schist. All loose or seamy portions were removed, and the whole foundation was sunk at least one metre into the rock, in order to prevent the dam from sliding. Where the surface of the rock was smooth, it was roughened either by exploding petards or else by coating it with Vassy cement into which bvilding-stones were stuck. The whole wall, including the facing, was built of rubble masonry, except the angle of the upper retreat, the parapets, and the corbels upon the outside facing. The stones were procured from the excavation for the foundation, from the new channel for the rivers, and from two neighboring quarries. The best stones were selected for the faces, where they showed a section of about 11.6 feet and joints of 2 to 1} inches. The stones varied in size from 2 to 7 cubic feet. In order to prevent unequal settling, the masonry was carried up about 5 feet high at a time over the whole wall. The top of each of these layers was left with as many projecting stones as possible, so as to bond it firmly with the next layer. Cut stones 2.6 feet long and about 1.1 feet high were placed in the front face in quincunx order, 4.6 metres (15.09 feet) from centre to centre, and projecting 1.3 feet. On the back face there are three rows of iron rings to facilitate repairs. The thickness of the dam at the highest level where the water is stored—44.5 metres (146 feet) above the bottom of the reservoir at the dam—is 6.37 metres (20.9 feet). Above this there is a guard-wall 5 metres (16 feet) high, having a thickness of 3.75 metres (12.3 feet) at the base and 3 metres (9.84 feet) at the top. This furnishes room for a carriage-way and two foot-paths. On the top of the guard-wall there are two parapets which add 0.5 metre (1.64 feet) to the total height of the dam. In order to prevent all leakage from the reservoir, the rock was stripped on the up-stream side of the dam for 60 to 80 feet, and all fissures that were discovered were carefully sealed with cement or masonry. Great pains were taken to make the joints between the dam and the rock on each side perfectly water-tight. A coating of 3 to4 inches of cement was placed at the angles formed by the facing of the dam with the rock into which the dam was imbedded. It was originally intended to make all the joints of the up-stream face with Vassy cement, but this plan was discontinued after the dam had been built about 49 feet high, as the introduction of water into the reservoir proved that ordinary mortar would answer just as well. Owing to the high altitude of the Furens Dam, work on the reservoir could only be carried on from May Ist to October 1st of each year. The balance of the time, however, stones were quarried and hauled to convenient positions. The materials required in con- struction were distributed by means of a railway located on the top of the wall, and which was raised as the work advanced. PLATE B. eaeNiamelnl emo) Furens Dam. (Front } Furens Dam. (Back.) FRENCH DAMS. 69 The masonry of the dam was commenced in 1862 and completed in 1866. Four superintendents and twenty-five to thirty masons were employed, and laid on an average 10 yards of masonry per day. The actual number of working days did not exceed 120 per annum. The total quantity of masonry in the dam was 52,300 cubic yards. The cost of impounding the water was 1.15 francs per cubic metre (0.0062 dollar per cubic foot). The work of each season was allowed to harden thoroughly, and was then tested by allowing the water to flow into the reservoir and finally over the dam. In December, 1865, there were 46 metres (150.91 feet) of water in the reservoir; in March, 1866, 47 metres (154.19 feet). The only effect produced by this great water-pressure was a dampness on the front face, which was doubtless due to the porosity of the stone and mortar. A ditch was dug in the front of the dam and left open for four months in order to detect any leakage, but remained perfectly dry. The description we have given above of the construction of the Furens Dam has been taken from the interesting memoirs published in the “ Annales des Ponts et Chaus- sées” by MM. Greeff and Delocre in 1866, and by M. Montgolfier in 1875. In concluding the brief account we have given of this great work, we will state that the Furens Dam is the highest reservoir wall of the present time, and that it is the first masonry dam, which has been built in accordance with correct scientific principles. Its construction has been in every respect a great success, owing to the care taken in all the details of the building by the eminent engineers who directed the work. The Pas du Riot Dam7 is situated about 8200 feet from the Furens Dam, and was constructed in 1872-78 in order to form a reservoir of 1,300,000 cubic metres (343,383,000 gallons) capacity for the city of Saint-Etienne. The dam is 34.50 metres (113.19 feet) high, and is built on a curve in plan. Its profile was based upon that of the Furens Dam. The Ternay Dam (Plate XXXVII.).—This dam was built to prevent inundations by the Ternay River, and to supply the town of Annonay, in the province of the Ardéche, with water. The costs of the construction were borne by the state, town, and manufac. turing interests. The account we give of this work is taken from the interesting memoir published in the “Annales des Ponts et Chaussées” for 1875 by M. Bouvier, who designed and con- structed the dam and reservoir under the general directions of M. Krantz, the Chief En- gineer. ; The vertical pressures in the masonry were not to exceed 7 kilos. per square centi- metre (7.16 tons of 2000 lbs. per square foot); the coefficient of friction necessary to prevent sliding was limited to 0.76. The profile of the dam proper is surmounted by a rectan- gular portion forming a guard-wall 3.65 metres (11.97 feet) high and 4 metres (13.12 feet) thick. The dam without the guard-wall is 34.35 metres (112.67 feet) high and 4.8 metres (15.74 feet) thick on top. The up-stream side of the prcfile is formed first by a vertical line 17.85 metres (58.56 feet) long, and then by two inclined lines, the first having a slope of 0.8 metre (2.62 feet) horizontal to 5.5 metres (18.04 feet) vertical; the second a slope of 3 metres (9.84 feet) to 11 metres (36.09 feet). The down-stream side of the profile is formed by a circular curve whose radius is 4§ metres (147.63 feet). The centre of the circle is 2.3 metres (7.54 feet) above the 70 DESIGN AND CO\STRUCTION OF MASONRY DAMS. crown of the dam. The curve terminates 9.3 metres (30.51 feet) above the base of the dam, the front face being completed by a tangent to the curve, whose horizontal pro- jection is 7.1 metres (23.29 feet). The total thickness of the dam at its base is 27.2 metres (89.25 feet). In his memoir describing the Ternay Dam, M. Bouvier advanced the formule we have given on page 12. The maximum pressure in this reservoir wall calculated by these formule amounts to g kilos. per square centimetre. M. Bouvier cites the experiments of M. Vicat to show that good hydraulic mortar may safely sustain pressures of 14.4 kilos. per square centimetre (14.73 tons of 2000 lbs. per square foot). The Ternay Dam was built of rubble masonry, the stones used being granite. M. Bouvier gives: The specific gravity of the granite,, . . . + « « « + 2,620 “ce “se 4“ “ce a“ mortar,. ». «© «© « «© «© « + 1.970 “a oe “ cc ce masonry, « « «© «© « © » « 2.35 The proportion of the stone to mortar was as 6 to 4. The wall was built on a curved plan, the radius being 400 metres (1312 feet). The capacity of the reservoir formed by the Ternay Dam is 2,600,000 cubic metres (686,- 766,000 gallons), which is sufficient storage-room for retaining all the flood-waters of the river. The dam and reservoir were built in 1865-1868. The Ban Dam!’ (Plate XXXVIII.) was constructed in 1867-1870 to form a reservoir of 1,800,000 cubic metres (475,454,000 gallons) capacity, from which the city of St. Cha- mond draws its water-supply. This dam is 46.30 metres (151.86 feet) high. It was built on a curved plan. The profile was determined by the method employed for the Furens dam, but a higher limit of pressure was taken, namely, 8 kilos. per square centimetre (8.18 tons of 2000 lbs. per square foot). The dam is founded on rock, and composed of rubble masonry. The Verdon Dam (Plate XXXIX.) was constructed in 1866-1870 to raise the level of the Verdon River sufficiently high to feed a canal which supplies the city of Aix (Provence) and other places with water. At the site selected for this work, near the village of Quinson, the width of the valley is only 115 to 130 feet, its rocky sides being almost vertical and about 160-200 feet high. The Verdon River has a fall of .003 foot in 1 foot, and its flow varies from 10 to 1200 cubic metres (2640-317,000 gallons) per second. To construct a dam across a river subject to great freshets, founding the wall on solid rock after excavating about 20 feet of gravel and boulders, was a difficult undertaking. For a detailed account of how the work was executed we must refer the reader to the interesting memoirs published by the Chief Engineer, M. de Tournadre, in the “Annales des Ponts et Chaussées” for 1872 (Ist semestre), from which we take the following description. The general dimensions of the dam are: Metres. Feet. Leeneiln a S. 4.x ew a em 40.00 T3193 Height above river-bed, . . . 1... . . 12.2 40.19 ae “ foundation, . . » 1 » » » 1806 59.06 Width at tep.. a 2 ja 6 @ @ ee ao » Be 14.17 6 OM DASE) 4 ae a Re ew HOOT 32.51 “of foundation, »« » «. . . « « « « 15.00 49.21 FRENCH DAMS. 7 The design of the dam was based on the assumption that it would be submerged 5 metres (16.4 feet) when the river had its maximum flow of 1200 cubic metres (317,000 gallons) per second. The profile had, therefore, to be made very strong, and special pre- cautions taken in the details of the construction. A great freshet occurring soon after the completion of the work proved the correctness of the above assumption. The foundation is built of concrete, and the dam proper of rubble with a cut-stone facing down-stream and a heavy cut-stone coping 0.75 metre (2.46 feet) thick. This coping forms six courses of voussoirs in plan, the stones being fastened together by iron clamps, and also secured to the up-stream side by iron dowels. The mortar used in the masonry was composed of hydraulic lime of Theil and river sand. The Verdom Dam is built circular in plan, the radius being 33.171 metres (108.83 feet) for the front face at the base. The foundation-mass of concrete, however, has a rectangular plan. To resist the high fall of the water passing over the dam during freshets, a rip-rap of large boulders is placed in front of the wall. Bouzey Dam™* (Plate XL.) was constructed in 1878 to 1881 near Epinal, France, to form a reservoir of about 1,875.000,000 U. S. gallons capacity for the ‘‘ Canal de 'Est.’’ The dam had a length of about 1700 feet on top. Its greatest height was 49 feet above the river-bed and 72 feet above the foundation. The dam was built straight in plan and had a profile which was calculated to be one of ‘‘ equal ’ resistance,’’ each joint being assumed perpendicular to the resultant of all the forces acting on it. The profile adopted did not originally include the shaded portions shown in Plate XL. The dam was founded on red sandstone, which was fissured and quite permeable. Considerable difficulty was experienced in the foundation-trench from springs. To prevent leakage under the dam a guard-wall, two metres thick, was built at the up-stream face from the solid rock to the river-bed, but the foundation of the dam itself was only excavated to fairly good bottom and not to the solid rock. The dam was completed in 1880, but the reservoir was not filled until about a year later. When the water reached a level 33 feet below the top of the dam, springs of about 2 cubic feet per second appeared on the lower side of the wall. This leakage was partly due to two vertical fissures which had been made in the wall by changes of temperature before the reservoir was filled. The water was raised very gradually in the reservoir. When it reached, on March 14, 1884, a level 10.5 feet below the top of the dam, a portion of the wall 444. feet long was shoved forward so as to form a curve, convex down-stream, having a versed sine of 1.1 feet. Four additional fissures appeared at the same time in the front face of the dam and increased the flow of the springs in front of the wall to about 8 cubic feet per second. No further motion took place in the dam although the water was kept at the level it had reached. The fissures in the wall opened in the winter and closed in summer on account of changes of temperature, their average width being about 0.28 inch. * Le Génie Civil for 1895 and Proc. Inst. C. E., vol. cxxv. 72 DESIGN AND CONSTRUCTION OF MASONRY DAMS. In 1885 the water was allowed to rise to the high-water level (1.97 feet below the top of the wall), and the reservoir was then emptied for inspection. It was found that the dam had separated from the guard-wall for a stretch of about 97 feet when it had been shoved forwards, and many fissures were discovered on the inner face. The masonry was repaired. To prevent the dam from sliding, an abutment was built in front of it and connected by an inclined wall which was toothed into the dam. A block of masonry was, also, built on the up-stream face to close the joint opened between the main dam and the guard-wall, and was surrounded by a bank of puddle, about 10 feet thick. The masonry added to the dam is shown by the shaded portions in Plate XL. Drains were placed in the masonry to carry off any water that might leak under the dam. The repairs mentioned were begun in 1888 and completed by September 14, 1889. The water was admitted to the reservoir again in November, 1889. On April 27, 1895, the water being at its highest level, about 594 feet of the central part of the dam was suddenly overturned at a plane about 33 feet below the top of the wall. The fracture was almost horizontal longitudinally. It was level transversely for about 12 feet and then dipped toward the outer face. The accident caused a great loss of life and property. The failure of the Bouzey Dam is supposed to have been due to a greater tension at the up-stream face than the masonry could resist. This tension was probably increased by an upward water-pressure under the dam, which had not been founded on an impervious stratum. The Pont Dam" (Plate XLI.) was built in 1883 on the Armacon River, at a distance of 24 miles from the city of Sémur. The dam is circular in plan,. having a radius of 400 metres (1312.40 feet) and a versed-sine of 7.10 metres (23.30 feet). The length of the dam on top is 150.89 metres (495.12 fect). The profile has a top width of 5 metres (16.4 feet), and is bounded as follows: on the back by a straight line having a batter of 0.05 metre per I metre of height; on the front, by a circular arc whose radius is 30 metres (98.43 feet) to a depth of 19 metres (62.34 feet) from the top, and which is continued by a tangent. The height of the dam proper is 20 metres (65.62 feet), to which the foundation adds about 6 metres (19.69 feet). There are 7 counterforts on the front face, 5 metres (16.40 feet) wide by 3 metres (9.84 feet) thick, inclined parallel to the front face of the dam, The dam was founded on rock and built of granite. When the reservoir was first filled, some water leaked through the dam, but the filtrations soon disappeared and the wall is now in excellent condition. The Chartrain or Tache Dam* (Plate XLII.) was constructed in 1888-92 on the Tache, an affluent of the river Renaison, which flows into the Loire to form a reservoir for supplying the city of Roanne with water. The capacity of the reservoir is 4,500,000 cubic metres (158,897,000 cubic feet), of which, however, 500,000 cubic metres have to be reserved for storm-water. The reservoir has a surface of 22 hectares (54.36 acres) and is supplied from a water-shed of 1400 hectares (52 square miles). * Vth International Congress on Inland Navigation. Report by M. Marius Bouvier on the Reservoirs in the South of France. FRENCH DAMS. 73 ‘The Chartrain Dam is the most recent example of the construction of a dam in France built according to a scientific profile. Its design was based on the following principles : Ist. The lines of pressure, reservoir full or empty, must be kept within the centre third of the profile. 2d. The maxima pressures in the masonry or on the foundations are not to exceed 11 kilogrammes per square centimetre. 3d. There must be no possibility of the dam’s sliding or shearing apart. The plan of the dam was curved to a radius of 400 metres. The Chartrain Dam was constructed of rubble masonry, made of porphyric rock and hydraulic mortar, weighing about 2400 kilogrammes per cubic metre (150 lbs. per cubic foot). The up-stream face was covered with a layer of artificial cement of slaked lime, 0.03 metre thick, made of equal parts of cement and sand, to Io metres below the coping. In spite of this coating there was considerable leakage through the dam at first. It is, however, steadily diminishing. The total cost of the Chartrain Reservoir was $2,100,000 or 0.47 frane per cubic metre stored. The Mouche Dam* (Plate XLIII.), completed in 1890, was constructed across the ‘fouche River, an affluent of the Marne, near the village of Saint-Ciergues, to form a storage reservoir of 8,648,000 cubic metres (305,365,000 cubic feet) capacity for storing water for “the canal of the Haute-Marne.” The surface of the reservoir at the level at which the water is to be stored is 97 hectares 46 ares (241.83 acres). The Mouche Dam was designed by M. Carlier, Chief Engineer. It is 410.25 metres (1346 feet) long and is built straight in plan. The depth of the water in the reservoir above the meadow of the thalweg is 28.98 metres (95.08 feet). As no good material for an earthen dam could be found near the site selected, it was decided to construct a masonry reservoir wall, although this involved an excavation of 7-12 metres below the surface of the ground to reach the marl-rock on which the dam was founded. 56 per cent of the total masonry of the dam was laid below the surface of the ground. The profile of the dam (Plate XLIII.) was determined by the method recommended by M. Bouvier and improved by M. Guillemain. Besides fixing a limit for the pressure to be permitted in the masonry, the French engineers adopted also the condition, first insisted upon by Prof. Rankine, that the lines of pressure, reservoir full or empty, should be kept within the centre third of the profile. In the case of “reservoir full” this condition was carried out absolutely, but for “the reservoir empty” a slight deviation from the condition was permitted, especially as the reservoir will never be entirely emptied. The probable weight of the masonry was determined by an experimental block containing 4 cubic metres. After diminishing for 25 days the weight of the block remained constant at 2150 kilos. per cubic metre (134.23 lbs. per cubic foot), which weight was adopted in the calculations. * Vth International Congress on Inland Navigation. Report by M. Gustave Cadart on the Reservoirs of the Department of the Haute-Marne. 74 DESIGN AND CONSTRUCTION OF MASONRY DAMS. The profile was determined by calculating the widths at horizontal sections two metres apart. Subsequently the pressures were determined on oblique sections from the foot of the up-stream facing and from other points. The maximum pressure per square centimetre in the masonry is 6.58 kilogrammes (13,478 lbs. per square foot), The top of the dam proper was made 3.50 metres wide and placed 2.05 metres above the highest water-level. As the dam was also to serve to carry a road 7 metres wide across the valley, the necessary additional width was obtained by con- structing on the down-stream face of the dam a half viaduct 3.5 metres wide, consisting of 40 semi-circular arches of 8 metres span. The arches form 8 groups of 5 arches each, which are separated from each other by abutmet-piers 2.80 metres thick. The ordinary piers have a thickness of only 1.80 metres at their lowest part. The foundation trench was excavated at least one metre into solid rock, and considerably deeper for three anchor-walls. The up-stream facing, formed of freestone coarsely prepared, was covered with three layers of burnt pitch and was afterwards whitewashed to prevent too great an absorption of heat. The Dam of Avignonet ® was constructed in 1899 to 1902 by the Society of Power and Light of Grenoble across the river Drac. The watershed of this river is mountainous and almost devoid of trees. This causes the discharge of the river to vary very much, the flow at low water being about 20-25 cubic metres (5 283-6,604 gallons) per second, while during floods the discharge amounts to over 1,000 cubic metres (264,140 gallons) per second. At the site of the dam the Drac flows through a very narrow gorge whose sides rise to a height of about 300 metres (984.2 feet). The gravel and stone carried by the stream during freshets have raised the original river-bed very much. As very deep trenches would have been required to reach bed-rock, and as it was essential to construct the foundations of the dam rapidly on account of the torrential nature of the Drac, it was decided not to go to bed-rock, but to found the dam on the compact gravel and fine sand in the river-bed which offered sufficient incompressibility and water-tightness. The dam was built entirely of concrete as an overflow weir, according to the profile shown in Fig. 26. Its principal dimensions are: Metres. Feet. Length on the crest line. 0032000 case ccwiese eens 60.00 196.84 ‘¢ at the level of the river... .........--..22. 45.00 147.63 Helglitune ssoctink dete e oe chistetae emia anee ere 23.00 75-45 Thickness at top... .-...-..----- eee e eee eee eee 4-95 15.58 & ES” (PASGt scam iti qesG a cmiewioe tars aise 23-90 78.40 The plan is curved to a radius of 200 metres (656.1 feet). Two cut-off walls, 4 metres high by 2.50 metres thick, were built into the gravel as shown in Fig. 26. An apron made of reinforced concrete protects the river-bed in front of the dam for a distance of about 20 metres. The dam has an outlet canal 70 metres long by 9 metres wide, the flow through which is controlled by a Stoney gate. B The descriptions of dams marked B have been taken from a series of articles on masonry dams by H. Bellet, Civil Engineer, which appeared in '‘La Houille Blanche”’ for 1905 and 1906, FRENCH DAMS. 7 a The Sioule Dam ® was constructed in 1902-1904 across the Sioule River, near Queuille (Department of Puy de Dome), by The Gas Company of Clermont-Ferrand, to store water and SS lb LATA Lede, Re VA - a -- VOOM SO Wr. AA Fic 26.—TuHeE DAM oF AVIGNONET. to obtain power. The dam was built according to the profile shown in Fig. 27, the principal dimensions being: M tres. Tcet. Genethton-tODy sis.ceecundiiimeenares eeeeeienes 120.CO 3903-71 8° Gt: (PASey sacs ui eeesossaedeieeee teeeed 60.00 196.84 Width at (Opies sc sthaeetdoinaeecaneeseatems 5.00 16.40 Se ME DasGaccssslnes cui tee a eemaneaaes ez <8 24.22 79.08 Maximum height... .......----- ee eee seen eens 30.00 98.42 The up-stream face is battered 1:10 from the top down for rz metres and then 18 per cent for the remaining distance. The down-stream face is battered 0.72:1 at the base and = 25m Fic. 27.—TuHE SIOULE Dam. 1:10 at the top, these batter-lines being joined by an arc of 15 metres radius. The plan of the dam is curved to a radius of 300 metres. The dam has two overflow weirs built about parallel with the valley, one at each end. The Miodeix Dam,® known also as the Dam of Sauviat (Department of Puy de Dome), was built in 1903 by the Power Company of Auvergne across le Miodeix stream, to store 76 DESIGN AND CONSTRUCTION OF MASONRY DAMS. water and furnish power. The maximum height of the dam above the foundations is 24.50 metres, the normal depth of water in the reservoir being 22 metres. It is constructed according to a triangular profile, the apex of the triangle being at the highest assumed water level, viz., 1 metre above the crest of the spillway. The tangents of the angles of inclination of the up-stream and down-stream faces are respectively 0.09 and 0.80, except at the top where the latter face is vertical, being joined with the inclined part of the face by an arc of 8 metres radius. The dam is 3 metres wide at the crest and 21 metres wide at the base. (See Plate XLIV.) The Turdine Dam® was constructed in 1902-1904 across the Turdine stream to form a reservoir of 817,000 cubic metres capacity for the water-supply of the City of Tarare. The dam is 25 metres high, 4 metres wide at the top and 19.91 metres wide at the base. It is built according to a triangular profile. The up-stream face is inclined .05:1 for the first 10 metres and then 0.833 metre in the last 15 metres. The down-stream face is vertical for 1.65 metres and then has a batter of o.80 metre per metre, the vertical and inclined parts of the face being joined by an arc of 15 metres radius. (Plate XLIV). The plan of the dam is curved to a rads of 250 metres. The dam is 120 metres long in the centre line of the crest. The top of the spillway is 0o.7o metre below the crest of the dam. The Dam of l’Echapre ® (Fig. 28) was built in 1894-98 across the stream 1’Echapre, an affluent of the Ondenon, to form a storage reservoir for the water-supply of Firminy, Department of the Loire. The reservoir, which is located about 3 kilometres from Fir- miny, has a storage capacity of 950,000 cubic metres (about 251,000,000 gallons) and is supplied from a watershed of 1,440 hectares (5.56 square miles). The principal dimensions of the dam are: Metres. Feet. Length on: Crest... «cases sue eess ssa vceonakic 165.00 541-34 “Ab DAS@.og sn citceeese ne eewoewie eek sa 45.00 147.63 POP: Widths gas seins me ceeee ee se tales aa 4.19 17.03 Width at: base: «sy sgeeeesedeavaredeincwees ve de 27.00 88.58 Maximum height above foundation... ........ 37.00 121.39 - depth. Of watetiiscas cae acacsens 38.30 115.80 The plan of the dam is curved to a radius of 350 metres (1,148.2 feet). To obtain a suitable foundation the excavation had to be made to a depth of 7-13 metres. The up-stream face is vertical for 30 metres, and the down-stream face has a batter of about 0.76 in 1.00, The masonry placed in the dam weighs 2,400 kilogrammes per cubic metre; the maximum pressure to which the masonry is subjected amounts to 11 kilo- grammes per square centimetre (about 11 tons per square foot). On top of the dam a roadway having on each side a sidewalk is constructed. In order to obtain the necessary width for the roadway and sidewalks, the thickness of the dam near the top is increased by corbeling out, the corbels being supported by masonry arches of 4 metres span, which are built in the down-stream face near the top. The arches are supported on pilasters built on the down-stream face, which are 1.20 metres wide and have a batter of 1:8. The total height of the arches is 11 metres and the maximum thickness is o.go metre. In order to make the dam as water-tight as possible its up-stream FRENCH DAMS. 77 face was given a coating of hydraulic mortar upon which a second coating of pure hydraulic cement was placed. The reservoir has a waste-weir 31 metres (101.7 feet) long. The outlet-pipes are placed in the rock on the left side of the valley and do not pass through the dam. This dam and the two following ones were designed and built by M. G. Reuss, Ingénieuer des Ponts et Chaussées, under the general direction of M. Delestrac, the Engineer of the Department of the Loire. They have all similar profiles (Fig. 28). The arches and corbeling at the top of these dams reduces the amount of masonry required and is ornamental. The Cotatay Dam® was built in 1900-04 on the Cotatay, an affluent of the Ondenon, to form a reservoir of 850,000 cubic metres capacity (about 225,000,000 gallons) for the water-supply of the City of Chambon-Feugerolles. The watershed sup- plying the reservoir contains 1,150 hectares (4.44 square miles). The dam has a maximum height of 44 metres (144.35 feet) above the foundation, the greatest depth of the water in the reservoir being 37 metres (121.39 feet). The crest of the Fic. 28—THE EcuapreE Dam. dam is 1 metre above high water. The top width of the dam is 4.60 metres and this is increased 0.50 metre by corbel- ing out, to obtain sufficient width for a roadway, which is constructed on top of the dam. The corbeling is supported by arches of 3 metres span, which are constructed on the down-stream face of the dam on a batter of 1:10. The plan of the dam is curved to a radius of 350 metres (1,148.2 feet). On the crest the length measures 155 metres (508.54 feet) and at the base 24 metres (78.73 feet). The waste-weir is 42.75 metres (140.25 feet) long. Two lines of outlet pipes provided with stop-cocks are laid in a tunnel on the right bank. Water can be drawn from the reservoir at the level of the tunnel and at a level 10 metres higher. The Ondenon Dam ® was built in 1901-04 to form a reservoir for the water-supply of the town of La Ricamarie. The reservoir stores 400,000 cubic metres (about 106,000,000 gallons) and is supplied from a watershed of 530 hectares (2.03 square miles). The dam has a maximum height of 37.50 metres (123.03 feet) above the foundation, the greatest depth of water in the reservoir being 32.60 metres (106.95 feet). The top of the dam is 0.50 metre above the high-water level. The dam is 4.70 metres wide at the top and 28.58 metres wide at the base. A roadway is constructed on top of the dam. Sufficient width for the purpose is obtained by corbeling out, the corbeling being supported by arches of 3 metres span, 0.60 metre deep. The pilasters of the arches are inclined 1.5. The plan of the dam is curved to a radius of 300 metres (984.2 feet). The length of the dam is 128 metres (419.96 feet) at the crest and 12 metres (39.37 feet) at the base. The waste-weir is 28.75 metres (94.32 feet) long. The outlet-pipes are laid through the dam. 78 DESIGN AND CONSTRUCTION OF MASONRY DAMS. The Cher Dam * (Fig. 29) is now (1907) in course of construction to form a resevoir of about 25,000,c00 cubic metres (about 6,604,000,000 gallons) for supplying water to the City of Montlugon (Department of Allier) and to supply power for some hydro-electric works, IW WALA Z A BZ ADAGE Z Fic. 29.—THE CHER Dam. The dam will have a maximum height of about 48 metres (157.48 feet) and the greatest depth of water in the reservoir will be about 45 metres (147.63 feet). The top width will be 4.70 metres and the width at the base will be 43 metres (141.1 feet). The plan of the dam will be curved to a radius of zoo metres (656.10 feet). * The author is indebted for the information given about the Cher dam to M. H. Bellet, C.E., of Lyons, France. DAMS IN VARIOUS PARTS OF EUROPE. 79 CHAPTER. IX. DAMS IN VARIOUS PARTS OF EUROPE. The Dam of Cagliari’ (Plate XLV.), situated on the Island of Sardinia at a distance of 13 miles from the city of Cagliari, was constructed in 1866 on the Corrongius River. The annual yield of this stream, derived from a watershed of 30,000 hectares (116 square miles), is estimated at 4,000,000 cubic metres (1,056,564,000 gallons). The reservoir is 125 metres (412 feet) above the level of the sea, and has a capacity of 1,000,000 cubic metres (264,141,000 gallons), The principal dimensions of the dam are: Metres. Feet. Length on top, . . . 2. 2. 6 «© © © © «© 105.0 344.50 at. bas@,« « & Bow ew Mw & a $06 164.00 PGiSNG. ae unde, Ss ee ee) Se a We IG 70.54 Width iat “tap, « 2 & @ w @ 6 w ew « 5.0 16.40 a DASE; 6. ob) eee “> AC Ge aes “ROTO 52.50 This reservoir wall was founded on rock, and built of rubble masonry composed of granite stones and hydraulic mortar made of lime of Cagliari, and Pozzolona of Rome, mixed with well-washed granitic sand. The Dam of Gorzente* was constructed in 1880-1883 on the Gorzente River to form a storage reservoir of 2,250,000 cubic metres’ (594,500,000 gallons’) capacity for the water-supply of the City of Genoa, Italy, and to furnish water power for the generation of electricity. This storage basin, known as the reservoir of the Lavezze, has a surface of 26 hectares (64 acres) and is supplied from a watershed of 1,769 hectares (6.8 square mules). The dam is built, according to the profile shown on Plate XLVI, in a narrow valley, its plan being curved up-stream. The principal dimensions of the dam are: Metres. Fect, Wength: at ‘créstsis:s «sce See tah oe seek eebanics 150.00 492.20 Maximum height above foundation............ 37.00 121.40 Vidi OP (OD eacnaswncideweramemminacad male 7.00 22.07 O60 NES ASG aieaicn! sie S odie aaron aie sie Viele oes 30-35 99-57 The dam is surmounted by a guard wall, 4 metres wide by 1.50 metres high. The dam was founded entirely on rock and was built of che serpentine stone found in that locality and with lime of Casale mixed with serpentine sand. As soon as the reservoir was filled the dam commenced to leak. In February 188s, before the waste channel was completed, a severe freshet raised the water in the reservoir more than 0.35 metre above the guard wall, causing some yielding of the dam. Borings made at different parts of the structure showed that the mortar had not sct properly, and it is quite probable that the dam would have been ruptured had it not been that it was * Article by Mr. H. Bellet, Civil Engineer, in ‘‘La Houille Blanche’’ for October 1906. 80 DESIGN AND CONSTRUCTION OF MASONRY DAMS. constructed in a narrow valley with a curved plan. As a result of this experience it was decided to strengthen the dam by counterforts. The outlet from the reservoir is not at the dam but at one side of the reservoir, where a special outlet chamber is constructed. To convey the water from the reservoir, which is located on the north slope of the Appenines, to Genoa, which lies on the south slope, a tunnel had to be driven through this mountain range. This tunnel, which begins at the outlet chamber, is 2300 metres (7,545 feet) long and has a slope of o.5 millimetre per metre. The tunnel, which is under pressure, is lined with masonry and has for its waterway a horseshoe section composed of a trapezoid (1.65 metres high, 1.70 metres wide at the base and 1.90 metres wide’ at the top) and ofa semicircle of 0.95 metre radius. The tunnel aqueduct is continued by two lines of steel pipes of 0.75 metre inner diameter, which are under pressure. The tunnel and pipe-line together are known as the Aqueduct of Ferrari-Galliera. The reservoir is provided with two waste-weirs. The first of these weirs, which is 7.50 metres long, is built adjoining the dam, its crest being 1.50 metres below the top of the dam. The second waste-weir is 4o metres long and has its crest o.5 metre below the top of the dam. A blow-off pipe controlled by suitable valves is embedded in the masonry 30 metres below the top of the dam and 14 metres below the aqueduct tunnel. It serves for scouring out the deposits that form in the reservoir. The Lagolungo Dam (Plate XLVII, Fig. 2) was constructed, about 1883, immediately above the Lavezze reservoir to form a second storage basin for the City of Genoa, Italy. This reservoir has a capacity of 3,640,000 cubic metres (961,500,000 gallons). The dam has a maximum height of 40 metres at the up-stream toe and 44 metres at the down- stream toe. The dam is 5 metres wide at the top and was originally surmounted by a guard wall 2.50 metres wide by 2 metres high. On the right side of the dam a waste-weir 22 metres long was constructed, with its crest at the level of the base of the guard wall. The dam is provided with four cast- iron outlet-pipes embedded in the masonry respectively 5, 10, 20, and 32.8 metres below the crest of the dam. These pipes have suitable valves on the down-stream side of the dam and discharge water from the reservoir either into the Lavezze Reservoir or into a conduit leading directly to the Ferrari-Galliera aqueduct. After twenty years’ experience with the reservoir it was decided, in 1903, to raise its water level 3 metres, increasing thereby the storage by 800,000 cubic metres. This was done by raising the waste-weir 3 metres and by replacing the original guard wall on top of the dam by a new one 4.25 metres high, 5 metres wide at the base, and 2.50 metres wide at the top. At the same time a second waste-weir, 18 metres long, was constructed with its crest at the same elevation as that of the first weir. It was estimated that in case of freshets o.60 metre of water might pass over the two waste-weirs. Flashboards were placed on top of the weirs to make it possible to retain the water at its greatest freshet height, increasing thereby the capacity of the reservoir by en additional 200,000 cubic metres. The Dam of the Lavignina was constructed to form a compensating reservoir of 1,000,000,000 cubic metres capacity to supply the riparian owners along the lower Gorzente with water. DAMS IN VARIOUS PARTS OF EUROPE. 81 The dam has a maximum height of 21.76 metres and is built according to a profile similar to those of the two dams described above. The Gileppe Dam * (Plate XLVIII).—The reservoir in the valley of the Gileppe was con- structed by the Belgian government to regulate the flow of this stream, and to furnish the important cloth manufactories at Verviers with a large supply of pure water. M. Bidaut, the Chief Engineer who designed the Gileppe Dam and reservoir, com- menced the preliminary studies in 1857, but, owing to various delays, his plans were not submitted to the ministry until 1868. According to careful observations, the watershed of the Gileppe, containing 4000 hectares (9880 acres), yields from 20-23 million cubic metres (5,283,000,000, to 6,075,000,000 gallons) of water per annum. It was decided to construct a reservoir having a surface of 80 hectares (198 acres) and capable of storing 12 million cubic metres (3,170,000,000 gallons), by building a dam 45 metres high (147.6 feet) across the valley of the Gileppe. The same storage capacity might have been obtained by constructing four different basins having dams only 27 metres (88.6 feet) high, but the plan of one reservoir with a high dam was found to be more economical. The Gileppe Dam was built curvilinear in plan, the radius being 500 metres (1640 feet). Its greatest height is 47 metres (154.2 feet). The length on top of the wall is 235 metres (771 feet), at the base 82 metres (269 feet). The breadth of the wall is 15 metres (49.22 feet) on top and 65.82 metres (216.5 feet) at the base. The foundations were carried I metre into the rock. With the exception of a band of cut stones at the top and bottom of the front face, and at the angles where the batters change, the whole wall was con- structed of rubble masonry, the total quantity amounting to 325,000 cubic yards. Although this massive dam was built with the utmost care, it was completed in six years. The work on the masonry progressed as follows: Cubic Yards of Masonry. 1870). 6 i a) eS Sw) le eRe wy So THO HAOO TST So koe BOW eS ES ee oe ce, Ra we. es HE FSOO FO72, 4 eh Sw wa ee BO BOO TOVSe a @a dew GA Ge di ceo: Bo Sage BS aoe Oe & 4 68900 TO 7A g. Seo8h, tay See ee BE GR eh aes OR, Re ae a ee. ew OO TOT Gris, cis de oS BP hate BE Bo PO RE ho de gr - 5A OO 325,000 The average yearly work of over 54,000 cubic yards has probably never been surpassed in the construction of any other single structure. It was accomplished by 80 to 100 masons under the direction of 8 to 10 foremen. The work per man amounted daily to from 2.6 to 3.2 cubic yards. The sandstone or limestone used in the wall came from neighboring quarries, which were located at least 50 metres (164 feet) from the site of the wall and above the level of its crown. Two narrow-gauge railways served to transport the building materials to the dam. * Die Thalsperre der Gileppe bei Verviers. Von Ingenieur F. Kuhn. Published in ‘‘ Der Civilingenieur,” 1879. 82 DESIGN AND CONSTRUCTION OF MASONRY DAMS. Before commencing the foundations two subterranean channels were excavated, one on each side of the dam, by means of which the Gileppe was turned from its bed during the construction. These channels served subsequently as ways for the cast-iron outlet- Pipes, by means of which water is drawn from two wells, each 2.8 metres (9.2 feet) diam. eter, placed in the reservoir. Two overflow-weirs, 2 metres (6.58 feet) below the crown of the dam and 25 metres. (82 feet) wide, situated one at each extremity, serve for letting the flood-waters escape. The carriage-road on top of the dam passes over the overflow-weir, ascending to the crown of the dam by grades of I in 7. The leakage through the dam when the reservoir was first filled amounted to about 5300 gallons per day. This was probably due to the fact that the wall had not been exposed to the action of water during construction, as was done with the Furens. Dam. The leakage soon diminished; but even four years after the reservoir had been in use, a certain amount of moisture was perceptible on the down-stream face. The total cost of the Gileppe Dam and reservoir was $874,000, amounting to 0.2: cent per cubic foot of storage room. The profile of the Gileppe Dam has been severely criticised for its extraordinary” top width of 15 metres (49.22 feet), and for involving about 75 per cent of useless. masonry. It stands, indeed, in striking contrast to the scientific designs adopted for the dams of Furens, Ternay, and Ban, and resembles more nearly the early Spanish. dams. To justify the great top width of the profile, it has been stated by the Belgian engineers that the dam was designed with a view of being raised to a greater height when more storage might be required. However, the main reason seems to have been a great timidity on the part of the Belgian engineers, who were fully impressed with the great body of water they were going to store (six times the contents of the Furens reservoir), and the calamity the failure of. the dam would cause. M. Bidaut, the Chief Engineer, went with his calculations of the stability of the dam even to-the extreme of supposing water to percolate. through the wall to such an extent that the specific gravity of the, masonry would, be reduced from 2.3 to 1.3. The Vyrnwy Dam, England, Plate XLIX, was constructed in 1882-90 to form a large storage reservoir on the Vyrnwy River for the water-supply of the city of Liverpool. This artificial lake, which is situated at a distance of 674 miles from the old reservoirs at Prescott, covers 1115 acres, at an clevation of 825 feet above the level of the sea. The Vyrnwy Dam is 1350 feet long on top, the plan being -straight. Its maximum. height above the foundation is 136 feet. The profile adopted differs from most of the. others described in this book in not being designed simply to resist the water-pressure, but to form also a waste-weir. The front face of the wall is made, therefore, to conform to the curve described by the water in overflowing, and to deflect it into the basin in front of the dam. The foundation was laid on a clay slate rock, which is frequently interspersed with hard volcanic ash, and ranges from a close-grained grit of dark bluish-gray color to a. fine slate--texture. The strata dip up-stream, the different beds varying in thickness and. hardness. Great care was taken in preparing this rock for the foundation. All projecting portions or any parts which seemed in the least doubtful were removed. GiLeprE Dam. (Front View.) ee i i) me GLLEPPE Dam. (Side View.) PLATE D. Vyrnwy DAM. DAMS IN VARIOUS PARTS OF EUROPE. 87 The dam was built of “Cyclopean rubble,” which, owing to the great precautions taken, has much greater strength than ordinary rubble. The stone used is of a similar kind to that excavated in the foundation. It weighs 2.06 tons per cubic yard, its specific gravity being 2.721 The quarry from which the stones were obtained is situated at a distance of about one mile from the dam, and the stones were transported to the work by means of a double-track railway of 3 feet gauge. The blocks were shaped roughly at the quarry. All thin, projecting pieces were cut off, and a flat but rough surface was prepared for the lower bed. The best stones were reserved for the faces, and were cut to templates, their upper and lower beds being dressed parallel and their sides made vertical. An idea of the average size of the stones employed may be obtained from the following statement of the stones discharged from the quarry for the year ending October 18, 1885: . means Wiley 2 ONE: in yheueceureaiwkecmudeewmeeesy 45 -99 pec cent. SLOnES.2 (OA TONSe iid warzeeneed Vaweseasss ante hdes 20.86 ve Stones 4. tO 8 (ONS) o.o csv eneieeie cee eedekeeeweeeue ae re OFF Before being placed in the wall, all stones, whatever their size, were scrubbed and sub- jected to jets of water under a pressure of 140 feet. In the beginning of the work the sand for mortar and the gravel for conrcete were obtained from the river-bed. As this material, however, contained a large amount of clay and oxide of iron, it was thoroughly washed in revolving clyinders having internal vanes arranged so as to lift and drop the sand and gravel. For the lower part of the dam the mortar was composed of two parts of this washed sand and one part of Portland cement. As the natural gravel after being cleansed still contained a large percentage of sand, the concrete was made of two parts of this gravel mixed with one part of Portland cement without any further addition of sand. Experiments made in 1883 showed that by pulverizing the quarry-refuse-rock and mixing it with the natural sand in the proportion of two parts of the former to one of the latter, a stronger mortar was produced by using two parts of this mixture to one part of Portland cement than was obtained when only the natural sand was employed in a similar proportion. After 1883 all the sand used was obtaincd in this manner, and it was found that the mortar produced from this mixture of sand had not only great strength, but also the very desirable quality of “an absence of shortness.” All the mortar used in the dam was made with Portland cement which was required to stand the following test for tensile strength: Of six briquettes, 8 days after being moulded, kept in water from the second to the seventh day, at least one had to sustain without fracture a tensile strain of 5 cwts. per square inch for one hour. The average strength of about gooo briquettes tested in this manner was 6kcwts. As regards fineness, it was specified that not over to per cent of the cement should be retained by a sieve having 60 brass, wires to the lineal inch and weighing 3} ounces per square foot. It is well known that Portland cement of great strength may be obtained by using a large amount of chalk in its manufacture; but unless the cement is burnt thoroughly it will contain lime in an uncombined state, which when mixed with water slakes and 88 DESIGN AND CONSTRUCTION OF MASONRY DAMS. swells, contracting subsequently when the surrounding cement is just acquiring its hard- ness. Most Portland cements have some free lime, which, however, owing to its great affinity for moisture, may be converted into a harmless hydrate of lime by merely exposing the cement to the air. To effect this purpose all the cement used for the Vyrnwy Dam was spread, 6 inches thick, on platforms placed one below the other and 18 inches apart. Each platform consisted of loose boards which could be turned so as to drop the cement on the platform below. In this manner it was exposed seven times, being left on each platform one or two days, depending upon the dampness of the air. Owing to the precautions taken with the cement, no “hair-cracks” have appeared in the mortar used in the work. The sand and cement were mixed dry in accurate proportions in revolving cylinders having internal vanes. Before passing out they were wetted uniformly by a water-spray. Originally the sand and cement were mixed 2 to 1, but later this proportion was changed to 24 to r. The dam was built in the following manner: A level bed was first prepared on the rock, or on the masonry already laid, and was covered with a 2-inch layer of cement mortar, which was beaten to free it of air. A large stone was then lowered into position by a steam-crane, and was beaten down into the mortar by blows from heavy hand- malls. Other large stones were similarly placed, but so as not to touch each other. The spaces left between them were filled either with rubble made with small stones or with concrete which was thrust into the narrow spaces with blunt swords. The work within the reach of each crane was brought up 6 to 8 feet before the crane was moved. In each course the large stones were laid so as to bond with those in the course below. There are no horizontal joints passing through the wall, as the top of each course was left with projecting stones and hollows, which permitted it to be well bonded with the next course. To make the back face thoroughly water-tight, the vertical joints for several feet from the face were filled with mortar alone into which broken stone was forced. Seven steam-cranes were used in the construction of the dam, each with its driver and 18 men laying on an average 40 cubic yards per day. The specific gravity of the masonry, based upon the actuai weights of the materials used up to the end of 1885, was found to be 2.577. Numerous tests made with g-inch cubes of concrete taken directly from the wagons as it went into the work showed the crushing strength of the concrete when one year old to be about 187 tons per square foot. The area of the typical section shown in Plate LI. is 8972 square feet. When the reservoir is empty and the front face of the wall is subjected to a normal wind-pressure of 40 lbs. per square foot, the maximum stress on the masonry amounts to 8.7 tons per square foot. When the reservoir is full and the wind is blowing down the valley with a force of 60 lbs. per square foot, the maximum stress on the masonry is 6.36 tons, and the angle made by the resultant pressure with a vertical line is 16° 39’. To prevent the possibility of a greater upward water-pressure under the dam, in case the foundation should prove to be pervious and the dam impervious, than that due to the 47 feet of water in front of the wall, a complete system of drains was constructed in the foundation. Where the bed-rock has the lowest elevation there are twenty-six such drains in a length of 198 feet of the wall. They are 9 to 12 inches square, and lie on the DAMS IN VARIOUS PARTS OF EUROPE. 89 rock near such places where leakage is apt to occur. The drains are kept 25 feet from the front face and 30 feet from the back face, and connect with a central tunnel, 4 feet high by 2’ 6” wide, which traverses the foundation longitudinally at an elevation of 46.5 feet above the base of the typical cross-section. By means of a cross-tunnel leading down- stream any water that may filter into the foundation above the elevation of the drains is discharged at the front face of the dam. The description we have given above has been taken from the “ Report of Mr. George F. Deacon, C. E., as to the Vyrnwy Masonry Dam,” made to the Water Committee of the city of Liverpool in December, 1885. The Thirlmere Dam was built in 1886-1893 at Thirlmere Lake, about 5 miles from Theswick, to form a reservoir for the water-supply of Manchester, England. Mr. George H. Hill was the engineer in charge of the work. The dam is built in plan on a reverse curve, in order to follow the ledge rock with a view of reducing the depth of the foundation-trench. The dam has a maximum height of about 62 feet. At the top it has a width of 18.5 feet, the width being increased to 51.75 feet at a depth of 58 feet below the crest. The up-stream face has a batter of 1:8 and the down-stream face is curved to a radius of 100 feet. The crest of the dam is 6.2 feet above high water in the reservoir. German Dams.—A number of masonry dams, backed on the up-stream side for about half the height by earthen embankments, have been constructed in Germany. This type of dam (Fig. 30) was designed by Professor Intze of Aachen. The embankment on the up-stream face is made of clay, gravel, and stones, and is paved. Its slope is 2:1. The object of this embankment is to make the dam water-tight at its base. Objections have been raised to the use cf such embankments on the grounds, First, that the embankment covers an important part of the dam, making it impossible to inspect it; and Second, that the water may filter down between the dam and the embankment along its vertical face, in which case the embankment may become saturated and cause greater pressures against the dam than those which would result from the water pressure. The following table, which is taken from an article on masonry dams by H. Bellet, Civil Engineer, which appeared in ‘‘La Houille Blanche” for June 1906, gives some of the dams that have been constructed according to this type: GERMAN DAMS. Height. Name. Location. Metres. Fest. Salbacha< ccscueeicavsien Ronsdorf ............ 23.90 LiNnP6S@: ooh ees meese aes Marienheide......... 24.50 Eschbach. jincn2se osc eas Remscheid ........... 25.00 BOVER yo 6 scien wash donw aan Hikeswagen ........ 25.00 Fuelbecker............. AlteNa. 26 cis ceea eas 27.00 Jubachs « s.0 cs asckes noes Meinerzhagen ........ 27.80 Glorbaeh.. 2 sce eee Breckerfeld........... 32.00 Hasperbach............. Haspe se iccce ve eae oe 33-70 Herbringhauser.........| Ludringhausen........ 34.00 Oestetng gs sdvguansrenes Plettenberg........... 36.00 FOANEE ees we eared deanes Meschede ............ 37-90 BMnepe: iancexsavcaean aus Altenvérde ........... 41.00 Sengbach.............6- SONNE, oa ucodiea dao’ 43.00 QUES cc acacsonsa ard wader g Sileda pacccwnnesaands 45.00 Wilts a aunadoekas whaiens Gemiund 4.556 h4ekeae 58.00 go DESIGN AND CONSTRUCTION OF MASONRY DAMS. The Remscheid Dam* was built in 1889 to 1892 across the Eschbach Valley, to form a storage reservoir of 35,310,500 cubic feet capacity for the water-supply of Remscheid, Germany. The plans for the work were made by Prof. O. Intze. The dam is about 82 feet high, and is 13 feet 14 inches wide on top and 49 feet 24 inches at the base. It is curved in plan to a radius of 410 feet. The profile is designed to. keep the lines of resistance within its centre third, reservoir full or empty. The dam contains about 617,935 cubic feet of masonry, weighing about 4045. pounds per cubic yard. The stone used is a hard Linneite slate, quarried near the dam. It has a specific gravity of 2.7. About 38 per cent of the masonry consists of mortar, composed of 1 part lime, 14 parts powdered Trass, and I part sand. This. mortar sets much more slowly than one made with cement, and can be left mixed a whole day without injury. To make the dam as water-tight as possible, the back face was plastered first with cement mortar and then with asphalt. A brick wall (13 to 24 bricks thick) was laid on top of the layer of asphalt, cement mortar being used. The dam has proved to be perfectly water-tight. The Einsiedel Dam + was built in 1890 to 1894 to form a reservoir storing about 95,000,000 gallons for the water-supply of the city of Chemnitz, Germany. The dam is 590 feet long on top. Its greatest height is 65.6 feet above the natural surface and about g2 feet above the foundation. The dam is 13.1 feet wide on top and 65.5 feet wide at the lowest foundation. In plan the wall is curved to a radius of about 1310 feet. ‘ ’ The dam was built of ‘‘ cyclopean rubble,’’ the stone used being hornblende slate, quartzite slate, and clay slate. The mortar consisted of I part cement, $ part fat lime, and 5 parts washed sand. About 31,600 cubic yards of masonry were laid in the dam, about one third of the contents being mortar. The waste-weir is 82 feet long. Water can be drawn from the reservoir through three gates placed at different elevations in the side of a gate-house built of concrete on the up-stream face of the dam. The outlet- and waste-pipes pass through a culvert in the dam, the inner end of which is closed by a masonry bulkhead. Stop-cocks placed in a vault at the lower face of the wall serve to control the flow through the pipes. The Urft Dam} (Fig. 30), the highest structure of its kind in Europe, was con- structed in 1901 to 1904 across the river Urft, near the City of Aachen, in Rhenish Prussia, Germany. It forms a reservoir of about 12,000,000,000 gallons capacity, which regulates the flow of the river and furnishes power and water for irrigation. The dam has a max- imum height of 58 metres (190.29 feet) above the foundation, the greatest depth of the watcr at the dam being 50.5 metres (165.68 feet). The dam was built according to the type of Professor Intze, mentioned above, a paved earthen embankment with a slope of 2:1 being placed against the up-stream face of the dam for half its height. The plan of the dam is curved to a radius of 200 metres (656.1 feet), the length of the structure on the crest being 226 metres (741.39 feet). A waste-weir, 90 metres (295.27 feet) long, * Engineering News of 1°96. + Eng neering Record of 1894. t Engineering News, July 16, 1903, ‘‘Zeitschrift des Vereins Deutscher Ingenicure,’”’ 1903, and “ La Houille Blanche,’’ Grenoble, France, June 1906. DAMS IN VARIOUS PARTS OF EUROPE. QI prolongs the dam at its north end. The top of this weir is 1:50 metres below the crest of the dam. Instead of being built in a straight line, the crest of the waste-weir is scalloped or wave-shaped in plan, with panels 20-25 feet wide, separated by buttresses. Several of these panels have gates which can be used to increase the discharging capacity of the weir. The dam is 5.5 metres (18.04 feet) wide on top and 50.5 metres (165.68 feet) wide at the base, the latter width being equal to the maximum depth of water in the reservoir at the dam. The crest is x metre above the highest water level. The dam is founded on. mica schist and slate, the foundation-trench being excavated to a depth of about 6 metres. The body of the dam was built of argillaceous slate, laid in courses inclined against the line of pressure. On the up-stream side the dam was URFT DAM, GERMANY. Scale in Meters 20 40 6. 5) (O 30 k——— Rad.=200.0 TLL 1 a ee ——: 5 ++ -o ARQ ~ Y fs SSS SS BS UL nn | STS ND DD > XY E = = Ms - | S yy Y YS YY Ze SS Be WkKWe 2 | 50.5 > 53,5 Fic. 39. faced with trap-rock for a depth of 3 feet, the stones being stepped on the battered portion ‘of the face. Between the body of the dam and the face wall a 1-inch layer of cement, ‘coated with asphalt, was placed. This was done to insure water-tightness, but, to provide for carrying off any water that might leak into the dam, two rows of drain-pipes (24-inch clay pipes) were placed vertically in the masonry near the up-stream face, the pipes in each row being about 8 feet apart. The pipes of each row are connected to a 6-inch header leading to two drain-tunnels, which are constructed through the dam near its centre Each of these drains is closed by a gate-chamber at the up-stream at its lowest level. They are continued as masonry conduits through the earth embank- face of the dam. From each gate-chamber a tower rises in which the stems of the gates are placed. ment. These pipes In each of the drainage-tunnels a 23-inch steel blow-off pipe is laid. extend into the gate-chambers, where two gate-valves, operated from tke top of tke towers, 92 DESIGN AND CONSTRUCTION OF MASONRY DAMS. are provided for each pipe. In addition to this each of the pipes has a third gate, placed just below the gate-chamber, which can be reached through the drain-tunnel. The wasteway is in natural rock, which is cut roughly into steps, about 5 feet high, in order to break the force of the water. These steps are covered with concrete to resist the erosion of the water. At the site of the dam the stream makes a loop. During the construction of the dam a temporary earthen dam was built across the stream some distance above the site of the masonry dam, at a point where only a narrow ridge of rock separated the site of the temporary dam from that of the permanent dam. A tunnel was driven through this ridge, to divert the river during the construction to a point below the site of the masonry dam. This tunnel, which passes under the spillway, was provided with a gate and serves now as a permanent drain-tunnel. An outlet-tunnel, 9,200 feet long, was driven about a mile north of the dam. It supplies water under a head of 360 feet to a power-house in an adjacent valley, where 8 turbines, of 1,250 H.P. each, drive electric generators for transmission to neighboring towns. The works were designed by Prof. Otto Intze of Aachen, under whose direction they have been constructed. The Komotau Dam* (Plate XLVII, Fig. 1), known also as the Kaiser Franz Joseph Dam, was constructed during the years 1901-1904 to form a reservoir of 700,000 cubic metres (184,898,700 gallons) for the water-supply of the City of Komotau, Bohemia. It is the highest dam in the Austrian Empire. The principal dimensions of the dam are as follows: Metres. Feet. Maximum height above foundation ............. 42.5 139-4 ne " SOS WGUTTACE:s: tars. ote ceteleweieiecs 35-5 116.5 a depth: Of Watery j.asics ocncecinciesecins 34-0 TII.5 ms PE WES POUNGAHON Spa .cec ke eeiaeaidies 16.0 52-5 LOp. Widthiscis.dseaciaas teitsnigu eaeiaecieades fteeee 4.0 13.1 Width at ‘basé..i2 cocnedenecee eieeusaknsaessiec 30.0 98.4 Joenpth) at iCrest. <2. o6 as ausaie any alae hetetiawisie iaieib isle 155-0 508.5 = Ht DOOM. cc hamess dasa tieeeesissneas 52.0 170.6 Volume Of. MaSOnT ic ecseviwcerie tera acneuades 41,000 cubic metres Specie gravity Of MASON. suns cewenienin ennene's 2.4 The plan of the dam is curved to a radius of 250 metres (820.1 feet), The dam is founded on gneiss rock and constructed of cyclopean masonry made of blocks of gneiss and Portland-cement concrete, except the ornamental work at the top of the dam, which is made of granite dimension stone. The maximum pressures in the masonry, for reservoir full and reservoir empty, are respectively 6.12 and 5.94 kilogrammes per square centimetre (about 6 tons per square foot). To insure water-tightness the up-stream face was given two layers of a mixture of tar and natural asphalt, which were protected towards the reservoir by a covering of con- *See Oesterreichische Wochenschrift fur den Oeffentlichen Baudienst, January 16, 1904. DAMS IN VARIOUS PARTS OF EUROPE. 93 crete, which was dove-tailed to the main body of the dam. To get rid of any water which might seep into the dam in spite of this precaution, drainage-pipes of .o8 metre diameter were placed vertically, with open joints, in small shafts in the masonry, 2 metres apart and x: metre from the up-stream face. These pipes were connected at the bottom by larger pipes which discharge the water collected in the masonry into a drainage-gallery. An outlet-tower is constructed on the up-stream face of the dam. It contains two stand-pipes, which admit water from the reservoir at different levels through openings con- trolled by valves operated from the top. The stand-pipes are connected to horizontal pipes laid in a gallery which is constructed in the dam. A waste-weir, 21 metres long, discharges all flood-waters into a wasteway constructed around the reservoir. The Komotau Reservoir was projected, as early as 1874, by Professor Harlacher of Prague, but twenty-seven years elapsed before the work was executed. The works were planned and constructed under the direction of Mr. Emst Landisch, Civil Engineer and Architect, who has charge of the public works of Komotau. Dr. Otto Lueger of Stuttgart acted as Consulting Engineer. 94 DESIGN AND CONSTRUCTION OF MASONRY DAMS. CHAPTER: Xx. DAMS IN ALGIERS. The Habra Dam (Plate L.)—The great results obtained by irrigation in Spain induced the French government to encourage similar improvements in Algiers. How much the condition of agriculture in that country depends upon a good supply of water may be judged from the fact that the average rainfall is only about 15 inches, of which quantity, moreover, only one thirty-seventh reaches the streams. The rain is very unequally distributed over the different seasons, and the idea, therefore, naturally suggests itself to store the surplus water of the rainy months for the time of drouth. Among the important reservoirs constructed by the French in Algiers’ for this purpose, the largest was that of the Habra River. Although the watershed of this stream contains one million hectares (3859 square miles), yet, owing to the climatic con- ditions stated above, the annual yield of water amounts to only 108,000,000 cubic metres (28,521,000,000 gallons). The variableness of the flow of the Habra River will be seen from the following figures: Litres. Gallons. Flow per second in summer, . . . . 2. 6 «© e «© © 500 132 « oe ‘8 WINtel; a «6 @ @ <<) w « we 37000 792 «6 6 e during great freshets, . . . . « «© 700,000 184,898 The construction of the Habra reservoir was undertaken in 1865 by a private company, formed under a charter from the French government. According to the original plans, the desired storage capacity, which was fixed at 30,000,000 cubic metres (7,924,000,000 gallons), was to be obtained by closing the valley of the stream by a high earthen dam. Two failures, however, of similar works in the province of Oran (Algiers), one situated on the Sig at Tabia and the other on the Tlelat River, caused the projectors of the Habra reservoir to modify their plans by substituting a dam of masonry for one of earth. The construction of the reservoir was commenced in November, 1865, but, owing to various delays, the work was not completed until May, 1873. After having been in successful use for about eight years, the Habra Dam was ruptured in December, 1881. This catastrophe, which occurred after an unusually severe storm, during which 6} inches of rain fell in a very short time, caused the destruction of several villages, of part of the city of Perregaux, situated 61 miles from the dam, and the loss of 209 lives. The failure of this dam cannot be attributed to any defect in the design, but was caused, in all probability, by faults in the execution of the work. The profile of the dam was determined by the method of M. Delocre, and con- sists, commencing at the top, of a rectangle and three trapezoids having the follow- ing dimensions: * The dams marked T are taken from ‘“ Bacini d’Irrigazione,” per G. Torricelli. Roma, 1885. DAMS IN ALGIERS. 95 HEIGHT. WipTH. Top. Bottom. In Metres. In Feet. In Metres. In Feet. In Metres. In Feet. I. Rectangle........ eee cecccovcece 6.00 19.68 4.30 14.10 4.30 14.10 2. Trapezoid. :svciae seas See eeeaae 9.60 31.49 4.30 I4.10 10.00 32.81 3. TrapeZOid ss sinsec sivewie cee cinesce's 10.00 32.81 10.00 32.81 Ig.10 62.65 A. “TrapeZ0id)s.sciccesscuswsesevwee ss 8.00 26.24 Ig.10 62.67 26.94 88.39 DOtalssiesicanneccesmsnseeaises 33.60 TIOK22, ||| caveisaeaanee ||) saree seauaye | Savisese, | aecaccae A parapet 1.5 metres (4.92 feet) wide by 2.4 metres (7.87 feet) high surmounted the wall, preventing the waves from passing over its top, and serving as a foot-bridge. What we have described above constituted the dam proper. It was founded entirely on rock, in the following manner: The irregularities of the rock surface were levelled with a bed of concrete, whose average depth was about 4 metres (13 feet). On this was laid a block of rubble masonry 2 metres high and projecting 2 metres beyond the front face of the wall. Upon this foundation the dam proper was built. The main dam was straight in plan and had a length of 325 metres (1066 feet). It was flanked by an_ overflow-wall, 125 metres (410 feet) long, making an angle of 35° with its direction. The total length of the dam was therefore 450 metres (1476 feet), the top of the overflow being 1.6 metres (5.25 feet) below that of the main wall. There were two scouring-galleries 35.7 metres (117.1 feet) apart, and having a cross- section of 1.2 metres wide by 2.24 metres high (3.94 feet by 7.35 feet) at the up- stream face, and of 1.5 metres wide by 4 metres high (4.92 feet by 13.12 feet) at the down-stream face. These galleries were closed by means of iron gates placed at their up-stream ends and worked from the top of the dam by means of rods and the proper gearing for hand-power. By opening the gates yearly it was thought that no deposits would form in their vicinity. Water was taken from the reservoir by means of two outlets, each being composed of two pipes, 0.80 metre (2.62 feet) in diameter, passing through the masonry. When the water was first allowed to fill the reservoir, the dam leaked to such an extent that it looked like a large filter. This loss of water ceased, however, in course of time. The Habra Dam was finished in the winter of 1871-72, but on March Io, 1872, part of the overflow-wall failed during a severe freshet, on account of a defective foundation. The plans of the Habra Dam and reservoir were prepared under the direction of M. Debrousse, C.E., President of the Society which constructed this work, and verified by M. Feburier, Consulting Engineer. M. Leon Pochet was in charge of the con- struction from 1869 to the end, and it is from the interesting memoir describing the work which this engineer published in the “Annales des Ponts et Chaussées ” for April, 1875, that we have taken the description given above. The causes which probably led to the failure of the main dam in December, 1881, are given very fully in the following: 96 DESIGN AND CONSTRUCTION OF MASONRY DAMS. Extract from a Memoir on the “Rupture of the Habra Dam” by Gaetano Crugnola, Ingegnere Capo Provinciale.* “The construction of the dam began in 1866, and the work was finished in 1871. It was founded completely upon a kind of calcareous grit of the Tertiary epoch, which did not present everywhere the same consistency. Between two strata of hard grit which con- stitute the principal base of the dam there are others more or less soft, alternating with argillaceous strata which had to be removed at certain points to a great depth and were replaced by good concrete. Moreover, we must state, first, that the most important stratum of grit had a very limited depth, which, however, was considered sufficient to support the weight of the whole construction. “Second. The plane of separation between the grit and the stratum of argillaceous schist of the Miocene period was not far distant, and had an inclination of 45° with reference to the horizon and towards the valley. “Third. The strata of grit were inclined at 30° with the horizon. “The material employed in the masonry had to be procured in the locality, as the construction of such a piece of work (which required 500 cubic metres for each lineal metre) was not possible except by using the building material indigenous to the valley. For so great a mass of masonry the materials had to be close at hand. Consequently, stones from the stratum of Tertiary grit upon which the dam was founded were used. It is important to know, in regard to the Habra Dam, that the strata of grit did not all present the same tenacity. Some had a very pronounced schistose structure, and, although the instructions of the ‘Superior Administration’ were clear and declared these stones defective, it cannot be assumed with certainty that none of this building material was used. “The sand employed was not perfectly good. In the beginning of the construction it was taken from the Habra stream, but, when the dam reached a height above the ordinary level of the Habra, the water became stagnant and the quarries were filled with sedimentary deposits. It then became necessary to work some quarries at a greater distance from the place. The sand from these quarries was clean and free from loam, but too fine to make good mortar. “ Moreover, it is important to state that the ‘Administration’ itself had permitted the use of a red earth instead of sand for the inner part of the dam. Now the red earth contained an excess of clay, amounting to from 22 to 24 per cent of its weight. This is the reason why the mortar could not be relied upon to furnish the necessary resist- ance. “ The lime, although hydraulic, was not very good. It was made from calcareous rock found on the banks of the Habra River, which contained from 1 to 10 per cent of , sand, and from 16 to 31 per cent of clay. For a construction which is destined to retain a column of water 34 metres high an eminently hydraulic lime should be employed, and it ought also to be kept in repose for a certain time before being used, in order to give the quicklime time enough to expand. “Tt is known that all cements and hydraulic limes contain a certain quantity of quick- * Published in the ‘‘ Ingegneria e Arti Industriali di Pareto e .Sacheri,’’ Torino, 1882. DAMS IN ALGIERS. 97: lime which does not expand immediately, but only after a certain time, so that the increase of volume of the cement causes porosity, if not actual cavities in the interior of the masonry, This property of expansion was known to the French engineer Minard in 1827. From his experiments it appears that this expansion is not “completed until twelve months after immersion, and sometimes not until after twenty-two months. This consid- eration is of great importance. If this expansion in the Habra Dam was on a large scale, it would evidently produce fatal consequences after a certain number of years. Let us now examine the dam from another point, which will show more clearly the defects which probably existed in the construction. It is not possible to make a dam absolutely impermeable, and the result at ‘ Furens,” where only a few humid spots appeared on the outside face of the wall, is to be regarded as exceptional. These filtrations remained for a certain time, and then disappeared completely. In the Habra Dam, however, the filtrations were numerous. When the water reached a height of 10 metres, they appeared soon on the outside face. As the level of the water rose, the leakage increased to such an extent that the dam looked like a gigantic filter. This phenomenon was attributed especially to the porous nature of the stones which were used. In the course of time the water of filtration deposited on the wall a thin, white, shiny stratum, which was a carbonate of lime like that of which stalactites are composed. This deposit was certainly derived from an excess of lime in the hydraulic cement, which was not transformed into a silicate, but remained dissolved in the water of filtration under the great pressure exerted by the liquid of the reservoir. On coming into contact with the air the lime became a carbonate and was deposited on the face of the wall. From the above observations we see that the masonry was not suitable for this kind of construction, and that the cement would gradually lose its hydraulic and cohesive properties. We have examined about all the circumstances which might have affected the stabil- ity of the construction, but cannot say definitely which of them caused the rupture of the dam, on account of not having some exact data with reference to the occurrence of that disaster. Nevertheless, we can say that the above-named circumstances, combined with the effect of the inundation of which we shall speak hereafter, caused the destruc- tion of the dam. The rupture was 100 metres (328 feet) long and 35 metres (115 feet) deep, going down to the base; from which it can be supposed that the foundations also may possibly have sunken. At any rate, the construction of the masonry, as regards the choice of materials, seems not to have been conducted with all the precaution which a work of such mag- nitude demands. On the other hand, we ought to observe that the rupture occurred after a disastrous inundation, which was accompanied by very unfavorable meteorological conditions. The hydrographic basin which furnishes the water to the Habra reservoir has an extension of 800,000,000 square metres (309 square miles). In a very short time the height of the water resulting from the rain was observed with an udometer to be 0.161 metre (0.53 foot) ; and as the rainfall was general in the whole basin, the total quantity of water can be estimated at 128,800,000 cubic metres (34,021,361,000 gallons). 98 ‘DESIGN AND CONSTRUCTION OF MASONRY DAMS. “As the evaporation could certainly not have amounted to much in such a short period of time, we can admit without exaggeration, keeping in mind the filtrations which would have been possible, that the dam permitted the passage in one night of more than 100,000,000 cubic metres of water (26,414,000,000 gallons). “Now it is easy to understand that such an immense quantity of water would have flowed over the dam, forming a large wave whose height can be calculated at about I metre (the flow was about 5000 cubic metres (1,320,705 gallons) per second). As the breast-wall was 2.4 metres (7.87 feet) high above the ordinary level of the basin, the total superelevation of the water can be placed at 3.90 metres (12.80 feet).* | Such an increase in the height of the basin could not, certainly, produce a notable change in the conditions of the stability as regards sliding. The pressure, however, on the exterior face would be remarkably increased. From an approximate calculation, taking into account the obliquity of the resultant, we have found that a superelevation of 1.50 metres (4.92 feet) above the ordinary level would be sufficient to cause pressures of 12 to 13 kilos. per square centimetre (12.29—13.31 tons of 2000 lbs. per square foot). From what we have said above, it will be seen that the superelevation was more than double the one we have assumed in the calculation, and that the masonry was consequently exposed in an extraordinary manner above the limits of safety, the conditions becoming still more unfavorable from the circumstance that the water over- flowed the top like a gigantic cascade. “In view of the catastrophes that may occur by constructing a reservoir, it will be asked if it is necessarily dangerous to accumulate such an immense quantity of water; but we reply without hesitation, No. The rupture of a dam which retains such a great volume of water will certainly be dangerous, especially if it is situated near populated places. But it can be asserted generally, that in the construction of such a wall we can follow all the laws depending upon its static conditions and the pressure of the water. which can be determined with certainty and without establishing any hypotheses which do not conform to the reality. If the masonry is carefully built, as it ought to be, both in the interior as well as inthe points which join the bottom and lateral faces, no danger of rupture need be feared.” The Tlelat Dam™ (Plate LI.) was built in 1869 on the Tlelat River to supply the village of Sante Barbe, situated at a distance of about 74 miles from its site, with water, and also for irrigation purposes. Its general dimensions are: Metres. Feet. Length on top, ‘ ig 99.0 324.80 PiGigntts case th. Woe Baa A eS oe ol. BIRO 68.90 Thickness at top, .......... 40 13.12 M basé, se as Oe ke LTS 40.34 The maximum pressure in the masonry is 6 kilos. per square centimetre (6.14 tons of 2000 Ibs. per square foot), and the back face has some tension. The capacity of the reservoir is 550,000 cubic metres (145,278,000 gallons), and the watershed sup- plying it contains 13,000 hectares (51 square miles). * The height of the wave observed at the moment of the rupture was 3.50 metres (11.48 feet), DAMS IN ALGIERS. 99 The back face of the dam is vertical; the front face is circular, having a radius of 40 metres (131.23 feet), the centre of the circle being 3.60 metres (11.81 feet) above the top of the dam. A parapet 1 metre high by 1.50 metres wide surmounts the wall. It has been decided to raise the dam 6 metres higher in order to obtain more storage. The Dam of Djidionia™ (Plate LII.), located on the river of this name, was built in 1873-75 to supply the villages of St. Aimé and Amadema with water. The reservoir has a capacity of 2,000,000 cubic metres (528,282,000 gallons), and is supplied from a hydrographic basin containing 85,000 hectares (328 square miles). The dam was built straight in plan. Its general dimensions are: Metres. ; Feet. Height above foundation, . . . .. .. . 17.0 55.78 ag of foundation, . . ..... . .) 8&5 27.89 Thickness at top of dam,. ..... . . 40 13.12 us “ base of dam, . . . . 2. ee INS B73 ne of foundation, . ...... =. 160 52.50 The maxima pressures are: Kilos per Tons of 2000 lbs. square centimetre. per square foot. Above foundation, . ........ 460 6.14 At base of foundation,. . . 2... . . 9.43 9.65 The inner face has a tension of more than 1 kilo. per square centimetre, but this does not seem to have injured the masonry. The profile is bounded by a vertical line up-stream, and on the down-stream side by a straight line having a slope of 0.055 to 1 for a depth of 6 metres (19.69 feet) from the top, and then by a circular curve whose centre is 4.50 metres (14.76 feet) below the top of the dam and whose radius is I9 metres (62.34 feet). It has already been decided to raise this dam 8 metres (26.25 feet), increasing thus the capacity to 5,000,000 cubic metres (132,062,000 gallons). The Gran Cheurfas Dam” (Plate LIII.), situated on the Mekerra River (Sig.) at a distance of about 9 miles from St. Dionigi, was constructed in 1882-84. Its general dimensions are: Metres. Feet. Length om top, « «+ % © # © # « » « FNS 508.40 as at Base: apa ack 4 Sala wa we 50 164.04 Height above foundation,. . . . .. . + 30 98.42 Width at top, . . 1. 6. . 2 2 we we ee 4 13.12 as i “Bases 2 oe 6 we Be ee ww &- 22 72.18 The dam is composed: (1) Of a foundation-mass of rubble 10 metres (32.81 feet) high, 41 metres (134.52 feet) thick at the base~ and 24 metres (78.72 feet) on top; (2) Of the wall proper, having both faces formed of parabolic surfaces. 100 DESIGN AND CONSTRUCTION OF MASONRY DAMS. The two parabole which bound the profile have the same axis, which is horizontal and at the level of the top of the dam. The vertices of the parabole are respectively at the front and back edge of the top of the profile. At the top of the foundation the up-stream parabola has an abscissa of 3.00 metres (9.84 feet), and the down-stream curve has an abscissa of 15 metres (49.21 feet). The maximum pressure on the masonry is 6 kilos. per square centimetre (6.14 tons of 2000 lbs. per square foot), and the back face has some tension. The capacity of the reservoir is 16,000,000 cubic metres (4,226,256,000 gallons). In 1885 part of the dam failed, the length of the breach being 40 metres (131.24 feet); but the dam has since been repaired. The Dam of Hamiz™ (Plate LIV.) is situated on the Hamiz River at a distance of about 43 miles from the village of Foundouk. It was built in 1885 to form a reservoir of 13,000,000 cubic metres (3,433,833,000 gallons) capacity. The watershed of this reservoir contains 14,000 hectares (§4 square miles). The dam is built of rubble masonry, is straight in plan, and has both faces curvilinear. The general dimensions of the dam are as follows: Metres. Feet. Length 0 160, = « « « & = 2 @ 2 4 « Bede 531.60 “ at, basé.s 2 gum -4i-m SF aoe. 4 AO 131.24 Height above bed of river, . . . . . . 38.0 124.68 s “foundation, . . . . . . . 4I.O 134.52 Thickness at top, . . . . 2. 2. 2s «© we 5.0 16.40 . "pase; sy e 8 & e ww % we =» « 27,8 QI.21 At a depth of 28.84 metres (94.62 feet) from the top the front face has an offset of I metre, the thickness of the dam at this point being 18.85 metres (61.85 feet). The maximum pressure at the front face is 11 kilos. per square centimetre (11.25 tons of 2000 lbs. per square foot). The maximum tension at the back face is 3 kilos. per square centimetre (3.06 tons of 2000 Ibs. per square foot). The profile of this dam was determined by the French method of “equal resist- ance.” * _— * See page 2. DAMS IN EGYPT. 101 CHAPTER XI. DAMS IN EGYPT. The Rosetta and Damietta Dams* were constructed across the two branches of the Nile bearing their respective names, at the head of the Delta of Egypt, to obtain water for irrigating the Delta. The two branches of the river divide the Delta into three divisions, each of which is supplied with water by an irrigation canal. Napoleon Bonaparte, when in Egypt in 1798 and 1799, predicted the construction of a dam at the head of the Delta to control the distribution of the water of the Nile into its two branches. Such a work was begun in 1833 by the Viceroy Mehemet Ali, who was so impatient to have it completed that he crowded a great many more laborers on the work than could be employed to advantage. In order to obtain the stone for the dams, he proposed to tear down the famous Gizeh Pyramids, and it was only by the engineer producing estimates to prove that it would be cheaper to quarry the stone that this act of vandalism was avoided. The work was stopped in 1835 on account of a plagu-. The scheme of building the two dams was revived in 1842 by Monsieur Mougel (after- wards Mougel Bey), who managed to interest Mehemet Ali in the project by combining plans for fortifications with those for the dams. These plans were executed in 1843-52. The original plans were somewhat modified. As finally built the Rosetta Dam has 61 arches and two locks, one at each end, and is 465 metres long between flanks. The Damietta Dam had originally 71 arches (since reduced to 61) and two locks, its length being 535 metres. According to the original design the dams had respectively 72 and 62 arches and each was provided, also, in the centre with a navigable opening 14.50 metres in width, which was always to remain open. Two arches, each of 5.50 metres span, were substituted for the navigable openings, and the place of three end arches was occupied by a lock constructed on that flank of the dam, where none had been originally provided. With the exception of the central arches just mentioned, all the others have spans of 5 metres. The original gates for closing the openings between the piers were shaped as the arc of a circle, supported at either end by iron rods radiating from the centre of the arc, where they were attached to massive iron collars, working round cast-iron pivots embedded in the masonry of the piers. These gates were to be lowered by their own weight and to be raised by com- pressed air pumped into the hollow ribs, but they could not be operated successfully and * History of the Barrage at the Head of the Delta of Egypt,” compiled by Major R. H. Brown (late R.E.), Inspector-General of Irrigation in Lower Egypt. 102 DESIGN AND CONSTRUCTION OF MASONRY DAMS. were replaced after 1884 by wrought-iron gates provided with rollers sliding in cast-iron grooves fixed in the piers, according to F. M. Stoney’s patent. As the maximum depth of water on the floor of the dam is 44 metres, each opening was given double grooves and two gates, the upper one being always 24 metres high. In the Damietta Dam the lower gates are all 2 metres high, but in the Rosetta Dam their heights vary from 1 to 24 metres owing to differences in the level of the floor between the piers, caused by repairs that were made after the dam had been completed. Powerful crab winches (two for each dam) travel- ing on continuous rails serve for lowering or raising the gates. Originally an iron grating, 30 centimetres high, was fixed into the piers across each opening between the bottom of the gates and the floor surface. These gratings were to allow some water to pass through the dam even when the gates were down, and were thus to prevent the deposit of mud in front of the gates. With a head of 1.75 metres the gratings of the Rosetta Dam discharged over 20,000,000 cubic metres per day. The gratings were subsequently closed to avoid the loss of water they entailed and its scouring action below the dam, which at one time was supposed to be due to a honeycombed foundation. The two dams are separated by a revetment wall about 1000 metres long, in the middle of which one of the irrigation canals begins. The Damietta Dam was commenced first and was completed without any special diffi- culties being encountered. The construction of the Rosetta Dam was begun in June, 1847. Impatient to have the work completed, Mehemet Ali ordered 1000 cubic metres of concrete, to be laid daily, regardless whether this could be done advantageously or not. The river happened to be a metre higher than in the preceding year, but the Viceroy’s orders had to be obeyed, and concrete was dumped into the foundation-trench in many places before it had been excavated to the properdepth. The folly of such hasty and defective construction was seen later when numerous leaks occurred under the dam and cracks appeared in the walls. Owing to the scour along the east bank of the Rosetta Branch, the river bottom at this bank was about 10 metres below the elevation fixed as the bottom of the foundation of the dam. At the west bank a considerable deposit of silt had to be excavated before the foundation-level of the dam was reached. Coffer-dams enclosing about five arches were used in constructing the dam. After the silt had been excavated to the desired depth concrete 3 metres deep was laid to form the floor of the dam and covered with brick and stone masonry 0.5 metre deep. On this floor the piers were built. At the eastern bank the river bed was raised to the elevation of the bottom of the foundation by dumping in loose stone. The interstices of this mass of stone soon became filled with silt and, contrary to expectation, this part of the foundation proved to be about the most water-tight of any. The coffer-dams were con- structed right on top of this mass of loose stone and silt, the sheet piles being driven in as far as possible. Sail-cloth was laid on the up-stream side of the piles and held in place by the force of the current. As much of the concrete for this part of the dam was placed in running water, a considerable quantity of the mortar was washed away, leaving the masonry honeycombed. Much of this concrete was found to be as soft as puddling, but in some places it set as hard as rock. No unusual difficulties were encountered in building the foundations within the coffer- dams except at arches 7 to 10 near the east bank, where sand of a particularly fine quality, dark in color and very light, with the springs strongly impregnated with decayed organic DAMS IN EGYPT. 103 matter, was met with. Although the dredger was working in still water, this sand poured in so fast between the sheet piles that the excavation could not be carried down to the desired depth. The concrete at this place had consequently only a depth of about 1.50 metres. Cracks appeared in the superstructure before the dam was subjected to pressure, and this part finally failed and was surrounded by a coffer-dam. Mehemet Ali died in 1848 without seeing the dams completed. He was succeeded by Allas Pasha, who had no faith in the project and wished to abandon the construction of the dams. He dismissed Monsieur Mougel in April, 1853, and placed Mazhar Bey in charge of the work. Public opinion obliged the new Viceroy to continue the construction, which was finally completed by 1861, at a cost for the dams, including pathways, parapets, turrets, etc., of $9,400,000, exclusive of the work done by enforced, unskilled labor, known as Corvée labor. Mr. Willcocks in his ‘‘ Egyptian Irrigation” places the total cost of the dams, fortifications, canal-heads, etc., at about $20,000,000. In 1863 the gates of the Rosetta Dam were closed for the first time, in order to supply more water to the Damietta Branch. The water-level above the dam was raised 1-1.40 metres. Under this pressure sand was forced out from below the floor of the dam and ominous cracks appeared in the wall. In 1867 a whole section of the Rosetta Dam, con- sisting of ten openings towards the west end, separated from the rest of the dam and was moved perceptibly down-stream. A coffer-dam 5 metres high by 2 metres wide was built around these ten openings and filled with stiff clay, overlaid by stone resting on the platform. During the construction and after the completion of the dams a number of commissions of Experts and Consulting Engineers were appointed to give their advice in connection with the work. The well-known English engineer Sir John (then Mr.) Fowler examined the dams in 1876 and pronounced the piers and arches to be of good construction but the floor to be defective. General J. H, Rundall, R.E., formerly Inspector-General of Irrigation to the Government of India, also, reported on the dams in 1876, and gave his advice as to what had to be done to make the structures safe. As the result of all these Commissions and Reports, and contrary to some of their conclusions, Rousseau Pasha, Director of Public Works, in his yearly report of 1883 on irrigation condemned the dams and stated that in their existing condition they could only be used to distribute the flow of the river between its two branches. In May, 1883, Sir Colin (then Colonel) Scott Moncrieff was placed by the Egyptian Government in charge of the Irrigation Department and Works, and a new period in the history of Egyptian irrigation commenced with his administration. In December, 1883, he placed Mr. Willcocks, whe had come from India to join the Egyptian Irrigation Service, at the dams to examine their condition. Improved sliding gates were introduced, as already stated, the gratings in the picrs were closed, and various repairs were made in addition to those already executed after the completion of the construction. In the summer of 1885 the Nile was very low, but the dams were made to retain as much as 3 metres on the Rosetta Branch and 1.76 metres on the Damietta Branch, giving the canals an increased level of 10 centimetres over the supply of 1884. But some of the cracks in the Rosetta Dam widened and there was a down-stream subsidence of the old coffer-dam put in years before to protect this most doubtful part of the work. The 104 DESIGN AND CONSTRUCTION OF MASONRY DAMS. Pressure was relieved as much as possible by throwing masses of stone round the cracked portion. In 1885 a loan of a million pounds sterling was obtained for irrigation works, and Lieut.- Colonel Western came from India to direct the construction of the works to be built under this loan, the most important of which was the restoration of the two dams across the Nile. At first Colonel Western thought seriously of abandoning these structures, but in 1886 the floor of part of the Rosetta Dam was successfully exposed for examination by the simple plan of forming earth banks so as to enclose 20 arches at the west end of the dam, and pumping out the water (44 metres deep) from the enclosed space, and as a result of this examination it was decided to restore the dams. This work consisted, in addition to necessary repairs to the foundation, in extending the floor up- and down-stream so as to increase the strata under the dam through which all leakage had to pass. To give additional security to the old work the existing floor was covered with a layer of Portland-cement concrete 1.25 metres thick, over which was laid a heavy pavement of dressed Trieste ashlar stone under the arches and over the down-stream apron, where the action of the river was most severe. The floor was extended up-stream 25 metres in rubble limestone masonry. Sheet piles, 5 metres long, were driven along the up-stream edge of this extension. Owing to special difficulties the new flooring often exceeded 2 metres in thickness. The floor of the Rosetta Dam as restored varies in thickness and is unlike that of the Damietta Dam, the floor of which is at the same level. The work of restoring the Rosetta Dam was begun in 1887 and completed by June 16, 1890. The total cost of restoring both dams has been 465,000 pounds sterling. The bene- fits resulting from the work done in 1887-1890 have been so considerable as to fully justify the expenditure incurred. Prior to 1884 the maximum head retained by the Rosetta Dam was 1.75 metres. The Damietta Dam wasalways open. Since the completion of the restora- tion the maxima heads retained by the two dams have been respectively 4.07 and 3.72 metres. The Assuan Dam* (Plates E and F) was constructed in 1898 to 1903 across the Nile at Assuan, about 700 miles from the Mediterranean, in order to retain the flood-waters of the river for irrigation. At the site of the dam the maximum flow of the river in an average year is about 353,000 cubic feet, while the minimum flow amounts to only 14,000 cubic feet. The importance of storing the excess of water during seasons of flood was recognized as early as the days of Mehemet Ali. By retaining the water in this manner, what is known as perennial irrigation can be substituted for the ancient basin system, and two or three crops can be raised per year instead of one. Various reports upon the project of constructing a dam across the Nile at Assuan were made by different engineers. Mr. Willcocks (now Sir William Willcocks, K.C.M.G.), M.Inst.C.E., Director General of Reservoirs for the Egyptian Government, published reports on this project in 1890 to 1894. An International Commission, composed of Sir Benjamin Baker, Signor Torricelli, and M. Boulé, made later a report on this subject. *See The Engineer, London, Dec. 12, 19, 26, 1902; ‘‘The Nile Reservoir Dam at Assuan,” by W. Willcecks, C.M.G., M.Inst.C.E., London, 1901; also, paper by Maurice Fitzmaurice, C.M.G., B.A.L, in Proc. Inst. C. E. for January, 1903- ‘WY Nvassy ‘A ALV Id PLATE. EF: AssuaAN Dam. DAMS IN EGYPT. 109 In 1898 a contract for constructing the Assuan Dam and a directing weir at Assiout, 350 miles down-stream, was awarded to Sir John Aird & Co., an English firm of contractors, for 42,000,000, which was to be paid in 60 half-yearly instalments of £78,613, commencing on July 1, 1903, the date fixed for the completion of the work. At the time of the signing of the contract, the late Mr. W. J. Wilson, M.Inst.C.E., had succeeded Mr. Willcocks as Director General of Reservoirs, and on Mr. Wilson’s death in August, 1900, Mr. A. L. Webh, C.M.G., M.Inst.C.E., took his place. Sir Benjamin Baker, K.C.B., K.C.M.G., was appointed Consulting Engineer of the Egyptian Govern- ment, and Mr. Frederick Wilfrid Scott Stokes, M.Inst.C.E., was place in immediate charge of the work. He was suceeeded in December, 1901, by Mr. C. R. May, M.Inst.C.E., who had previously been principal assistant. The plans adopted for the Assuan Dam were practically those prepared by Mr. W. Will- cocks in 1895, with the exception of the cornice and the further change that the dam was located on a straight line, whereas Mr. Willcocks had chosen a broken line for the location with a view of making the average depth of the foundation as little as possible. The Assuan Dam had to be constructed in such a manner as to be able to discharge through sluices the whole flow of the Nile (the maximum recorded being 494,500 cubic feet per second in 1878-79) during the period when the river carried much silt, viz., July Ist to December Ist. No water was to pass over the top of the dam. The site of the dam was selected at the head of the first cataract of the Nile, at Assuan, where the whole structure could be founded on rock, and where there was an abundance of good granite for the masonry. The length of the dam is about 6,400 feet, including a lock on the west bank. It con- sists of two parts: a solid masonry dam 1,800 feet long commencing on the east bank, and a masonry dam 4,600 feet long containing the sluices and the lock on the west bank. The whole structure contains about 700,000 cubic yards of masonry. Plate LV* shows the profile of the solid part of the dam. The greatest height of the dam above the foundation is about 96 feet, the maximum depth of water in the rcscr- voir being about 65.6 feet at the dam. The top of the dam is 9.84 feet above high water. It is 23 feet wide where the sluices are located and 17.78 feet wide for the solid wall. The batters of the down-stream and up-stream faces are respectively 1 in 14 and 1 in 18. The roadway running along the top of the dam is 16.4 feet wide for the part that contains the sluices and only 9.8 feet wide for the solid part. With two exceptions, the sluices are divided into groups of ten, the length of solid wall between the individual sluices being 16.4 feet. Between two adjoining groups of sluices there is a length of 32.8 feet of solid wall, and buttresses 26 feet wide and 3.77 feet thick are added at these points, for the sake of appearance rather than for strength. These buttresses are about 240 feet apart. There are 180 sluiceways through the dam, viz., 140 lower sluices 6.56 feet wide by 22.96 feet high and 40 upper sluices 6.56 feet wide and 11.48 feet high. They are located at four different levels. Sixty-five sluices were placed with their sills practically on a level with the bed of the river. Forty of these sluices are lined with cast iron and the * A copy of an official drawing, from which this plate was made, was kindly loaned the author by Mr. Fr :d- eric Cope Whitehouse, who also furnished valuable information about the dams in Egypt. Ito DESIGN AND CONSTRUCTION OF MASONRY DAMS. remaining ones with ashlar masonry. According to the original plans all sluiceways were to be lined with ashlar. Cast iron was only resorted to to expedite the work at points where the foundation had to be carried down to a considerable depth. The plates used for the cast-iron lining are 1$ to 14 inches thick. Each plate has two vertical ribs 11.8 inches deep, which bond into the masonry. The plates are connected together at the vertical webs by 14-inch bolts. A layer of felt about } inch thick is placed between the flanges of the vertical ribs to admit expansion, Seventy-five sluices have their sills 14.76 feet above the river-bed. Twenty-five of these sluices are provided with self-balanced roller gates of the Stoney kind, the remaining fifty having ordinary sliding gates, which are only operated when the “ head’’ of water has been sufficiently reduced. Eighteen sluiceways were placed 27.88 feet and twenty-two sluiceways 41 feet above the bed of the river. The arrangement of sluiceways described above makes it possible to draw down the reservoir gradually without having too much head on the sluice-gates. The body of the dam is constructed of granite rubble masonry laid in Portland-cement mortar, mixed 4 to 1, except in the foundation and at the sides, where it is 2to1. The slopes are faced with squared, rock-faced granite, laid in courses varying from 12 to 24 inches in thickness. This masonry was laid on the up-stream slope in 2 to 1 Portland-cement mortar and on the down-stream slope in similar mortar, mixed 4to 1. The facing-stones were laid by means of derricks, but the body of the dam was formed of stones that could be carried on men’s backs from the wagons to the dam. The average weight of the masonry is about 149.5 pounds per cubic foot. The maxima pressures in the masonry are calculated to be at the down-stream and up-stream faces respectively 4 and 5.8 tons per square foot. In order to permit navigation past the dam a canal was constructed on the west bank of the river, partly in rock excavation and partly on embankment. It is about 6,540 feet long, 49.2 feet wide on its bed, and has four locks, which provide for a total descent of 68.9 feet. Each lock has a total length of 263 feet and a bottom width of 31.2 feet. The lock gates range in height from 62.34 to 29.53 feet and have to be worked under a head of 5 to 66 feet according to whether the reservoir is empty or full. They are all single- leaved gates of the Stoney pattern and roll into recesses, constructed in the masonry sides of the locks, at right angles to their general direction. Each gate is suspended from a carriage supported by rollers and traveling on a pair of rails, which rest on a bridge. The portion of the bridge over the recess is fixed, but the part over the lock is hinged at one end and is raised into a vertical position when the gate is in the recess. When the gate is to be closed, the hinged part of the bridge is lowered and the gate is moved across the lock and rests against steel groins at the sides and on a steel sill at the bottom. Valve openings are provided in the gates for filling or emptying the locks. About December Ist the water of the Nile is usually free of silt. The gates are to be closed about this time and the reservoir is to be filled during the months of December, January, and February. The reservoir will usually be drawn down during the months of May, June, and July. ‘wv LooIssy ay et oe Ss es py Fe > = Reet FL as eis TH, 5, ©, Saas 2 Fy ey DD ALVTd ‘WYq LOOISSY w A Me, ike Cai k nd ROALD ETL, Hd a ead iby Nel ee, cee ‘H ALVW Td DAMS IN EGYPT. 115 The reservoir has a length of about 143 miles, including the river-bed where the water fevel has veen raised and will store about 37,612 million cubic feet. The work of constructing the Assuan Dam was commenced in the summer of 1808. The first stone was laid in the dam on February 12, 1899, by the Duke of Connaught and the masonry was finished by June, 1902, about a year ahead of the contract time. This speed in the construction was made possible by the very low level of the river for two consecu- tive years. The work done included 824,000 cubic yards of excavation and 704,000 cubic yards of masonry. The sluice-gates of the dam were closed for the first time on October 20, 1902. The works on the Nile were formally opened on December 10, 1902, by the Khedive and by the Duke of Connaught. The contract price was £1,500,000 for the Assuan Dam and £500,000 for the Assiout weir. Owing to the fact that the foundation had to be excavated in some places to a much greater depth than expected, the actual cash cost of the Assuan Dam amounted to £2,450,000, which is about £62.5 per million cubic feet stored or £10 per million imperial gallons. The Assiout Dam (PlatesG and H) was constructed in 1898 to 1903 across the Nile, about 350 miles down-stream from the Assuan Dam in order to divert the water of the river at low water into two large irrigation canals. The dam consists of a masonry dam about 2,769 feet long extended on both sides by earthen banks, making a total length of about 3,937 feet. There are 111 arched openings of 16 feet 4 inches span in the masonry dam. They can be closed by steel sluice-gates 16 feet high. The piers and arches are founded upon a masonry platform 87 feet wide by Io feet thick. This platform is protected on its up-stream and down-stream sides by a continuous and impermeable line of cast iron tongued and grooved sheet-piling with cemented joints. This piling extends into the sand bed of the river to a depth of 23 feet below the upper surface of the platform and prevents it from being undermined. The river-bed is protected against erosion for a width of 67 feet up-stream by a stone paving laid on a clay puddle to check infiltration, and on the down-stream side for the same width by a stone paving having an inverted filter-bed underneath, so that any springs that may be caused by the water above the sluices shall not carry sand with them from beneath the paving. The piers between the openings have a length of 51 feet up- and down-stream and are 6.56 feet wide with the exception of every thirtieth pier, which has double this width. The roadway is 41 feet above the top of the masonry platform. The dam has a maximum height of about 48 feet, the maximum head of water retained being about 33.5 feet. It is constructed of granite, the foundation platform mentioned above being of concrete. A lock 262.5 feet long by 52.8 feet wide and capable of passing the largest Nile steamers was constructed at the dam. 116 DESIGN AND CONSTRUCTION OF MASONRY DAMS. CHAPTER XII. DAMS IN ASIA AND AUSTRALASIA. The Poona Dam (Plate LVI.) was constructed to form a large reservoir, Lake Fife, on the Mutha River, 10 miles west of Poona, for irrigating a large district of land near Poona and also for furnishing that place with a water-supply. This project was first proposed by Col. Fife, R.E., in 1863, but the final plans were not approved and the work commenced until the latter part of 1868. . The dam was founded on rock and constructed entirely of uncoursed rubble. Its maximum height is 98 feet above the river-bed and 108 feet above the foundation. Its length is 5136 feet, 1453 feet of which form the waste-weir, whose crest is II feet below the top of the dam. The line of the dam is formed of different tangents. At their intersections the wall is reinforced by heavy buttresses of masonry. The top-width of the dam, on the different tangents, varies according to the height of the structure. As the masonry showed signs of weakness after being completed and subjected to water-pressure, it was reinforced by an earthen bank, having a top-width of 60 feet and a height of 30 feet, which was constructed against the lower face of the dam. The total cost of the structure was $630,000. The dam backs up the water for 14 miles and forms a reservoir having a capacity of 3,281,200,000 cubic feet and a surface of 3681 acres. Only <9 feet of depth of. water is available, owing to the elevation which had to be given to the canals that. are fed from the reservoir. The catchment basin, above the dam, contains 196 square miles on which the annual rainfall is about 200 inches. The Tansa Damt+ (Plate LVII.) was constructed to form a large reservoir for the water-supply of Bombay. This project was first proposed by Major Hector Tullock, R.E., in 1870. The final plans were prepared by Mr. W. Clerk, who has had full charge of the construction of the works as Executive Engineer. The total length of the dam is 8800 feet and its maximum height above the foundations is 118 feet. The structure is, however, designed sufficiently strong to permit of its height being increased. 17 feet, in which case its length would be 9350 feet. * Irrigation in India, by Herbert M. Wilson (see XIIth Annual Report, U. S. Geological Survey). {See Engineering News, June 30, 1892. ** Engineering Record, December Ig, 1891. «* Xlith Annual Report of the U. S. Geological Survey. Irrigation in India, by Herbert M. Wilson. DAMS IN ASIA AND AUSTRALASIA. 117 1650 lineal feet of the dam forms the waste-weir, the crest of which is 3 feet below the top of the dam. The reservoir has an area of 8 square miles. The available depth of water above the sill of the discharge-sluices is only 20 feet. The net available capacity of the reservoir is 691,300,000 cubic feet, but this might be much increased, if necessary, by placing the sluice-gates lower. The catchment basin above the dam is only 52% square miles. Owing to the steepness of the slopes and a rainfall of 150-200 inches per annum, the daily discharge from this basin is estimated at about 8,000,000 cubic feet per day. The site of the dam is in a dense forest and jungle. To carry on the work a village had to be built for the native workmen and a macadamized road, 8 miles long, had to be constructed to the nearest railroad station. The dam was founded throughout on rock, the excavation for the foundations being in places 45 feet deep. Its alignment consists of two tangents, located so as to make the excavation to the bed-rock as little as possible. The dam was constructed entirely of uncoursed rubble masonry, roughly scabbled on the facing. The stones used were hard trap or greenstone, in pieces which could be carried by two men. An excellent hydraulic lime was obtained from the nodules of limestone, called kunker, which are found in the ground in abundance. Most of the cement used in India is obtained from these kunkers, which are generally about the size of a man’s fist, although in the Ganges Valley they are found in blocks weighing 100 pounds or more. They are found in the clay deposits, which are very abundant in India. The cement was burnt at the site of the dam. Kunker nodules were excavated some feet below the surface of the ground, exposed to the sun, dried, beaten, and washed clean, before being burnt. The sand used, clean, sharp trap or quartz, was carefully washed before being mixed with the cement. Some idea of the magnitude of this piece of construction can be formed by the following items of work performed: Total excavation, . »« © e e © « « «+ 261,127 cubic yards, Loose rubble-stone,. .« « e« e © e « « 544,700 “ s Lime, . «© © © © © © © © @ © © @ @ 81,700 “ “ Washed sand, “© © © © © © © @ © 122,555 s * e Rubble masonry, . . « « « « © « « 408,520 “ The proportion of the mortar (consisting of 1 part cement to I} parts of sand) im the masonry was found by a careful calculation to be 3675 per cent. In the lower part of the dam some Portland cement was used. The largest amount of masonry per month was laid in January 1891, when 700 masons laid 26,000 cubic yards of rubble. During the working season (May to October), g000-12,000 men were employed on the work. 118 DESIGN AND CONSTRUCTION OF MASONRY DAMS. During the rainy season the work had to be suspended. The construction was commenced by the contractors, Glover & Co., in March 1886, and completed in April 1891, 15 months ahead of the contract time. The cost.of the dam was about $1,000,000. The masonry has proved to be perfectly water-tight. The Bhatgur Dam* was constructed on the Yeluand River, about 40 miles south of Poona,. in the Presidency of Bombay, to form a large reservoir for irrigation purposes. The uncertainty of the rainfall in a portion of the Poona collectorate led Col. Fife, R.E., in 1863, to make surveys to find some means of supplying this region with water. This work was soon discontinued, but resumed subsequently by Mr. J. E. Whiting, C.E., and continued to 1871, when the final plans were decided upon. The works were carried out under the direction of Mr. Whiting. They consist of the Bhatgur reservoir, having a capacity of 5,510,740,000 cubic feet, of the Nira canal, 129 miles long, and of a diversion-weir, at the head of the canal, 19 miles below the reservoir site. The reservoir is formed by a masonry dam having the following general dimensions: Length of dam, . . . . . 2 © «© © © © « « 4067 feet. Maximum height above foundation, . . . »« »« »« 130 “ Top-width, . . . « « « «© © © © © © © @ 12 Bottom-width, eo © «© © © © © © © © © © 8 7374 es The maxima pressures in the masonry are: At down-stream face, . . . « » » 5.8 tons per square foot. At upstream face, 4 4 a w a » « OF * “ a é The profile of the dam was determined by a modern formula, similar to that of M. Bouvier’s. . The catchment basin above the dam contains 128 square miles. Waste-weirs, having a total length of 810 feet, are constructed in the body of the main dam, at both ends. They can pass a depth of water of 8 feet. The roadway is carried over the weirs by a series of arches having spans of Io feet. To pass the floods, which amount, at times, to 50,000 cubic feet per second, there are, in addition to the waste-weirs, twenty under-sluices, 4 X 8 feet in area, having their sills 60 feet below high-water mark. With this great head, the sluices can discharge 20,000 cubic feet per second, the average flood. The sluice-openings are lined with the best ashlar masonry, and are closed by iron gates, which slide vertically and are operated by steel screws, worked from the top of the dam by a female capstan-screw turned by hand levers. * XIIth Annual Report of the U. S. Geological Survey. Irrigation in India, by Herbert M. Wilson. Engineering Record, December 19, 1891, and July 30, 1892. DAMS IN ASIA AND AUSTRALASIA. 11g The main object of the sluices is to discharge the water from the reservoir into the river in which it flows about 20 miles to the diversion-weir at the head of the Nira canal. A less number of sluices would have been snfficient for this purpose, the object of having so many being to prevent the silting up of the reservoir. This can only be accomplished by keeping all of the sluices partially open, when the river carries much sediment. In this connection, Mr. A. Hill, the superintending engineer, states: “Scouring sluices have little effect unless the area of the openings is great compared to the area of the floods. To remove silt already deposited they are useless, as has been proved by the manner in which they have silted up at Lake Fife and at Vir and other places where their area is small compared with that of the area of the floods. At Bhatgur they are intended not to remove silt deposited already, but to prevent its deposit by carrying it off while in suspension. If the dam is high and the discharge of the under-sluices will keep the flood level below the full-supply level, then they will be efficient. If the dam is low and the sluices will not keep the flood level below full-supply level, they will have little effect.” Automatic sluice-gates 8 feet by 10 feet, patented by Mr. E. K. Reinold, are to be placed on the waste-weirs. They will be arranged so as to be wide open when the floods reach a level of 8 feet below the crest of the dam, and to close gradually as the water lowers. The Betwa Dam* has been built recently across the valley of the Betwa River, an affluent of the Jumna River, in India,‘to divert its water into an irrigation canal, and to form a large storage reservoir, having a capacity of 1,603,000,000 cubic feet. Water is supplied in this manner to about 150,000 acres of land, which are contained in a region which has an annual rainfall of only 35 inches. The Betwa project was first proposed by General Strachey in 1855. It was investigated by various engineers from time to time, but the plans were not finally approved by the Government until 1873. The flow of the Betwa River varies from 50 cubic feet per second to 750,000. To pass the large quantity of water in time of freshets, the whole dam was built as an overfall weir. It was skilfully located at a wide part of the river, where a rocky ledge offered a good foundation. The total length of the dam is 32096 feet, its height varying from 0.4 feet to 60 feet. The plan is convex up-stream. Two islands divide the weir into three parts. As originally proposed, the dam was to have a top-width of 10.5 feet and a slope on both faces of 10 feet horizontal for 254% feet vertical The Chief Engineer, Col. Greathed, changed the plan, however, so as to make the top-width 15 feet and the down-stream face nearly vertical, so that 6 inches depth of water would pass over the weir without falling on the face of the dam. The dam was made excessively strong, its bottom-width being greater than its height. A water-cushion was formed in front of the weir, by building a subsidiary dam, * XIIth Annual Report of the U. S. Geological Survey. Irrigation in India, by Herbert M. Wilson. 120 DESIGN AND CONSTRUCTION OF MASONRY DAMS. having a maximum height of 18 fect, about 1,400 feet down-stream from the main structure, across the channel of the river. Below the water, thus backed up against the dam, a large block of masonry 15 feet wide by about 20 feet high was constructed in front of the dam. The body of the dam was built of rubble masonry, coursed at both faces and laid in native hydraulic-lime cement. The coping was made of granite ashlar, 18 inches thick, laid in Portland-cement mortar. The dam is provided with suitable sluices for scouring the reservoir and for controlling the flow into the canal. The Periar Dam (Plate LVIII) was constructed in 1888-98 across the Periar River,* in the Province of Madras, India, to form a reservoir of about 13,1c0,0co,o0o cubic feet capacity for irrigating purposes. The water is conveyed into the valley of the Vigay River by means of a tunnel 6,650 feet long, having an area of 80 square feet, and is used for irrigating about 140,000 acres of land. The project of diverting water from the Periar River to the Vigay Valley was con- sidered as early as 1808 by Sir James Caldwell, who rejected the scheme as unworthy of consideration. In 1867 Major Ryves revived the project and made a report recommending the con- struction of an earthen dam, 162 feet high, across the Periar River. Colonel Pennycuick, who was given full charge of the project in 1868, proposed the construction of a masonry dam instead of one of earth, and worked out the details of the plans that were finally adopted. The cost of the reservoir, tunnel, and auxiliary works was estimated at $3,220,000. The construction of the masonry dam was commenced in 1888 and was completed in 1897. The profile adopted for the dam is shown on Plate LVIII. It was based on the conditions that the lines of pressure, reservoir full or empty, should be kept within the centre third of the profile, and that the maxima pressures, at the back or front face of the dam, should never exceed 18,000 lbs. per square foot, calculated by M. Bouvier’s formule. Owing to the difficulty experienced in obtaining skilled masons, it was determined to build the dam of concrete formed of 25 parts of hydraulic lime, 30 of sand, and 100 of broken stone. Both faces of the dam, however, were to be constructed of uncoursed rubble. The ingredients of the concrete were mixed mechanically by means of turbine wheels. The lime used was obtained from a quarry situated about 16 miles from the dam, and was of excellent quality, being about equal to the well-known “Theil lime” which was used for the large masonry dams near St. Etienne, France. Good, sharp, syenitic sand was found in the river-bed. Most of the stone for the masonry was obtained from the excavations made in connec- tion with this work. About 185,000 cubic yards of masonry was required for the dam. There are two waste-ways, one on each bank of the river, for which depressions in the hills will be used. They aggregate 920 fcet in length. * Written also “Periyar River.” DAMS IN ASIA AND AUSTRALASIA. 121 The construction of the Periar Dam involved unusual difficulties, the work on the foundations having been limited to the three dry months January, February, and March. From the end of May to the beginning of December the ordinary flow of the Periar River is about 4000 cubic feet per second. In January the discharge commences to diminish very much and amounts to only about 250 cubic feet per second. During February and March it is even less. The drainage area back of the dam is 300 square miles, on which annually 63-200 inches of rain fall, the average being about 125 inches. The depth of water flowing off the shed is about 49 inches yearly. But the flow of water in the river was not the only difficulty to be overcome. From the end of March to the beginning of June the malaria is deadly. Some idea of the difficulties involved in this construction may be formed from the following extract of a letter written by Colonel Pennycuick, the Chief Engineer of the work, to the writer in April 1890: “The peculiarity of this work is not so much the actual height of the dam (173 feet), as the combination of height with the size of the river, the discharge of which rises to over 120,000 cubic feet per second at times, and the peculiar conditions of the site, which is in a jungle inhabited by nothing but elephants, bison, and tigers, seventeen miles from the nearest habitation, and eighty-three from the nearest railway station. Labor has to be paid for at appalling rates, and the country bears a bad name for fever, of which the natives are much afraid. We have, in fact, to stop work entirely on that account for three months, and those the best of the year for river work; add to this that except in February and March you cannot be certain of a fort- night, at a time, without a flood, and that it is an every-day occurrence for the discharge to rise in a few hours from 500 cubic feet per second to 4000 or more, and you will understand that putting a dam across a river of this kind is not an easy job.” For a full account of how the difficulties involved in building the foundation of the Periar Dam were overcome we refer the reader to a series of articles on this subject by A. T. Mackenzie, A.M.I.C.E., in “Engineering” for 1892, and to a condensed account in “Engineering Record” of December 31, 1892. See also “the XIIth Annual Report of the U. S. Geological Survey. Irrigation in India, by Herbert M. Wilson.” The Beetaloo Dam,* in South Australia, was constructed in 1888-1890 to form a reservoir of 800,000,000 imperial gallons’ capacity for impounding water for the domestic water-supply and irrigation needs of a district of 1715 square miles, including several towns. The water is distributed by 255 miles of pipes 2-18 inches in diameter. The dam was constructed entirely of concrete mixed by machinery, the total quantity required being about 60,000 cubic yards. * Engineering News, May 30, 1891, and September 19, 1891. 122 DESIGN AND CONSTRUCTION OF MASONRY DAMS. Its general dimensions are as follows: Maximum, height, « 2 «© « «© « # « « © « « « 416 feet, Wid At tepiy 6 6 6k we ee A Gi eee @ SS a © DOUGH, 6 4 we & ¢ © a << &-¢ es Ito “ Lene BE OR,. & aie eh ew ee Re ee ae BR Spillway 200 feet long by 5 feet deep. The plan was curved to a radius of 1414 feet. The profile adopted for the dam was Prof. Rankine’s Logarithmic type (see Plate III). The masonry was founded entirely on rock. The reservoir formed has a length of 14 miles, an average width of 530 feet, and a depth at the dam of 105 feet. The work was begun in February 1888 and completed in October 18g0, the total cost being $570,000. Mr. A. B. Moncrieff was Chief Engineer. The Geelong Dam®* (Plate LIX.)—This dam was built across the valley of Stony Creek to form a reservoir for the water-supply of Victoria, Australia. It is built on a curvilinear plan, the radius of the vertical part of the back face being 300 feet. The masonry consists entirely of concrete, as it was thought to be cheaper than rubble, and also to form a more perfect monolith. The concrete was made of broken sandstone, mixed in a puddling-mill with hydraulic mortar which was composed of Portland cement and pit-sand. The best results were obtained by mixing the ingredients in the following proportions: 2 StONE eo yi we a a a a a OR arts pOCHEENINGS: fi oe BG Gn Se ee Bem ein SB Te DANS se. as wk oR So aL Re ae ee ee a ce et ok a TO Gemtient;, 3 aus. Goan & Wo ae Oe wo ewe AO Ree a Ge ee Total, @ 26 & « we 8 8 ow ee @ @ « » Bde parts: The stone of which the concrete was made weighed about 163 pounds per cubic foot. The average weight of the concrete was 143 pounds per cubic foot. The cement and sand were mixed dry, then made into mortar and thrown over the broken stone. Great pains were taken to place the concrete before the cement commenced to set. The work was carried up in courses a few inches thick, each course being rammed until the mortar flushed the surface. Before commencing a new course the surface of the preceding one was well watered and mopped over with cement grout immediately in advance of the new concrete. The Geelong Dam is coped with heavy blue stones, which are 3’ 3” wide by 1’ 9” deep. Although waves four feet high break over the top of the dam, not the slightest damage is apparent. Two pipes, 24” diameter, pass through the dam: one serves for the “outlet,” and * Proc. Inst. C. E., vol. Ivi., p. 93. DAMS IN ASIA AND AUSTRALASIA. 123 the other, which is placed at a lower level, to scour the reservoir. Both pipes have stop- cocks on the down-stream side of the dam. When the Geelong reservoir was first filed, a little water found its way through the dam; but this leakage soon stopped, owing to hard incrustations of lime .being formed on the dam. The Tytam Dam (Plate LX) * was constructed near Hong Kong, about 1887, for the Tytam Water Works. The foundation was laid on decomposed granite and boulders, as solid rock could not be found without going to a great depth. Owing to the difficulty of securing skilled masons for this work, it was decided to build the dam of stones about 3 to 6 cubic feet in size, laid in a matrix of concrete. The wall was constructed in the following manner: The inner face was composed of ashlar masonry of granite, laid in courses one foot high with plenty of headers. The side joints of the stones were grouted, the mortar being composed of 1 part Portland cement to 2 parts of sand. Next to the inner face 2 feet of “extra fine” concrete, composed of 4 parts of stone (1 cubes), 6 parts of sand, and 2} parts of Portland cement, was placed in order to form a water-tight skin. Next came 5 feet of “fine concrete,” composed of 44 parts of stone, 34 parts of sand, and 1 part of Portland cement. The “hearting” of the wall consists of “fine concrete” mixed as above, with stones 3 to 6 cubic feet in size imbedded in it. These stones were not placed closer than 3 inches from each other, the spaces between them being filled with concrete, which is well rammed. The outer face was carried up in steps for conve- nience of getting across the valley. It was not built exactly as shown in Plate LX. The facing is only one stone thick, and has its back irregular so as to bond with the concrete. The dam was constructed in courses about 2 feet thick, and inclined up-stream so that the front face was about 24 feet higher than tie back face. Each course had plenty of projecting stones to bond it with the next one. After the outer facing and the rubble-concrete hearting of a course had been laid, the “‘fine concrete” was placed between this masonry and planks. The back face was then carried up, and finally the “extra fine” concrete was rammed between this face and the “fine concrete.” About three fifths of the bulk of the whole wall consists of concrete and two fifths of stone. The best London Portland cement was used, about one barrel of cement being required per cubic yard of masonry. The stone for the concrete was crushed to pass through a 13” hole by machinery, and was mixed with the mortar in revolving cylinders. The screenings from the “crusher” were used as sand, this article being very scarce. The river sand used was not washed, as the clay, or rather decomposed granite, it contained was considered an advartare as con- ducing to water-tightness. For the same reason the engineers in charge of this work used plenty of sand in the concrete, and took care not to have it too sharp or clean, the object being not so much to obtain strength as to make the mortar impervious. The foundation of the dam was prepared in the following manner: After cleaning the surface of decomposed rock and boulders thoroughly, liquid cement mortar, mixed 3 to 1, was spread over it; then 3 inches of stiffer mortar was placed. Before this mortar could dry, 18 inches of “extra fine” concrete was laid, then 3 feet of fine concrete, and finally the rubble blocks. * This description was written in 1887. 724 DESIGN AND CONSTRUCTION OF MASONRY DAMS. To allow any water that might leak into the wall to escape freely, perforated zinc pipes 1$ inches diameter were placed in the masonry about 5 feet apart, and later on only bamboos; but this precaution was hardly necessary. When the water had risen to the top of the fourth step, the leakage could be carried off by a one-inch pipe with- out pressure. The water will be taken from the reservoir by means of a valve-well having inlets at different elevations. The well is placed at the centre of the dam, which is reinforced at this point by a pier. A cast-iron midfeather divides the well into halves, one being full of water and the other dry. The valves are placed in the dry part. The description of the Tytam Dam which we have given above has been taken from a letter of Mr. James Orange, the engineer in charge of the work, addressed to Mr. B. S. Church, Chief Engineer of the New Croton Aqueduct, to whom we are indebted for this information. The Toolsee Dam.* was built according to the logarithmic profile designed by Prof. Rankine (see Plate III), its total height above bed-rock being 79 feet. It forms a lake for the water-supply of Bombay. The Meer Allum Dam, India, was constructed about 1800 to form a reservoir, known as Meer Allum Lake, from which the city of Hyderabad draws its water-supply. The YYW Lp a ie yyy SECTION A-B SECTION C-D Fic. 31.—MEER Attum Dam. reservoir covers about gco acres of land and stores about 2,123,000,000 gallons of water. The greatest depth of water in the reservoir is about 50 feet. * Spon's Dictionary of Engineering, Vol. VIII, p. 2743. +The description of the Meer Allum Dam and Fig. 31 are taken from “Irrigation Engineering,” by H. M. Wilson, M. Am. Soc. C. E. See aiso Eng-neering Record, January 10, 1903. DAMS IN ASIA AND AUSTRALASIA. 125 The watershed of the reservoir is hilly and undulating and is well covered with jungle. The main feeder of the lake takes its rise from the river Esee and is about eight miles long. The dam, which forms in plan a large arch about half a mile long, consists of 21 smaller arches or scallops, which transmit the water pressure to solid-masonry buttresses. The small arches or scallops have spans of 70-147 feet. Fig. 31 shows the largest of these spans, which is built in the centre of the dam. Both faces of the arch are vertical except near the top, where the thickness of the arch is reduced from 84 feet to 3 feet by steps. A waste-weir is constructed at one end of the dam,-but is insufficient to discharge the water flowing into the reservoir during heavy rainstorms. In such cases about one or two inches of water flows over the crest of the dam. . The Belubula Dam, New South Wales,* was built about 1898, across the Belubula River, to form a reservoir for storing water and furnishing power for the Lyndhurst-Gold- fields Company of New South Wales. The dam is located in a narrow gorge, just above a succession of falls having a total descent of 175 feet. The valley above this gorge is of such width and slope that 16 feet of water stores about 652,000,000 gallons and gives a head of nearly 200 feet for turbines that are located about half a mile below the dam. . The rock at the site of the dam lies in a number of sharp ridges parallel with the axis of the stream with deep channels between. To have built an ordinary masonry wall in such a location would have involved expensive foundation work. Mr. Oscar Schulze, C.E., of Sydney, who designed the work and directed its execution, decided therefore to construct a buttressed wall, to be built largely of brick, as this was the cheapest available material in that locality. The dam has a total crest length, including the waste-weir, of 431 feet and a maximum height of 60 feet. The foundation is laid in concrete, varying in height from 1 to 23 feet, and above this there is 36 feet g inches of brickwork. In the central part of the dam there are six buttresses of brickwork, 28 feet apart, centre to centre, which form piers for five elliptical brick arches which are 4 feet thick at the bottom, 1 foot 7 inches thick at the top, and lean down-stream at an angle of 60°. The buttresses are 4o feet long, 12 feet wide where they abut against the wall, and 5 feet wide at the outer end. Each buttress, as it is carried up, forms a segment of a circle of 36 feet 2 inches radius and it diminishes in thickness from 84 feet at the centre to 4 feet at the outer circum- ference. The spandrels between the arches are filled with concrete which covers the crown of the arches to a depth of 12 inches and joins the side walls of the dam, which are built of concrete in which large boulders were placed to save expense. The overflow, which is constructed at one end of a side wall, is 65 feet wide. It is divided by piers into five sluiceways. Provision is also made for passing water over the tops of the arches in cases of high floods. During the construction the river flowed through an arched outlet at the base of the dam, which has been fitted as an emergency outlet for the reservoir by building out a projection on the water face of the dam, in which * Engineering News, September 8, 1898. 126 DESIGN AND CONSTRUCTION OF MASONRY DAMS. a well is constructed. This well is covered by a 12-inch wooden lid that can be raised by a 5o-ton hydraulic ram, which is worked by a pump at the back of the wall. The dam has a 12-inch outlet-pipe and two 6-inch scour-pipes, which are carried through the dam. The Barossa Dam,* South Australia, Fig. 32, was constructed in 1899-1903 to form a reservoir for supplying the town of Gawler, South Australia, and the surrounding farming district with water. ‘Chaln fonce standard BY String course of 40 Ib, ES Z ils Shhod at jotnte. yan yy ! a & i + Re \ | SASS SSS SN SDNT3A: 00S _ SOC Argillaceous.and Arenaceous Laminated Rock with Micaceous Shale Joints Fic. 32.—Barossa Dam. The dam is located in a narrow valley with a steep rock cliff, about 100 feet high on one side and a gently sloping spur of the range on the other side. The dam was built of concrete on a curved plan, the radius of the up-stream side of the top of the dam being 200 feet. It is 44 feet wide at the top and the greatest thickness of the concrete above the line of the foundation is 34 feet at the ground-line. The dam has a height of 95 feet above the bed of the creek across which it is built, the maximum height above the * Engincering News, April 7, 1904. DAMS IN ASIA AND AUSTRALASIA. 127 foundation being 112 feet. It was founded entirely on rock which was carefully stepped for the reception of the thrust of the arch into the wall on both sides. The profile adopted for the dam is of the triangular type (Fig. 32), the section being considerably reduced from a “gravity section” on account of the dam’s being built on a curved plan. Great pains were taken to establish by experiments the best proportions for the ingre- dients of the concrete. After the concrete had been brought to the ratural surface moulding timbers were introduced, which were hung on bolts built into the wall at every four feet vertical. Before inserting these bolts, they were covered with paper from the cement casks and tied around with cotton, which facilitated their removal from the wall. After the bolts and the paper were withdrawn, the holes were washed clean and filled with mortar. In the upper 15 feet of the wall string courses of iron tram-rails were built in horizontally, 40 tons being used. The dam was completed in February, 1903, but the reservoir was not completely filled until September, 1903. The atmospheric temperature during the construction varied from 30° to 168° F, The Cataract Dam, New South Wales,* has been under construction since October, 1902, and is to be completed during the year 1907. It will form a reservoir of 21,000,000,000 imperial gallons capacity for the water-supply of Sydney. The dam will be 811 feet long and 16 feet wide on top, 194 feet high above bed- rock, and 158 feet wide at the base. Its plan is straight. Thc maximum depth of water in the reservoir will be 148 feet. The heart of the dam is being built of large blocks of sandstone, laid in Portland-cement mortar, the joints being filled with concrete. This masonry is faced on the up-stream side with concrete blocks (about 5X2} X2 feet in size) made of crushed bluestone or basalt and Portland-cement mortar. The blocks are backed by about 3 feet of bluestone concrete. On the down-stream side the dam is faced with concrete, about 6 feet thick. Drains are placed in the body of the dam and will dis- charge the seepage water at the down-stream face. A waste-weir 720 feet long is provided, its crest being 7 feet below the top of the dam. Four 48-inch pipes provided with suitable valves were laid in the dam and discharged the river during the construction. Two of these pipes will form the permanent outlet of the reservoir. * Engineering Record, November 5, 1904, and April 20, 1907; Engineering News, December 6, 1906. 128 DESIGN AND CONSTRUCTION OF MASONRY DAMS. CHAPTER XIII. AMERICAN DAMS. The Boyd’s Corners Dam* (Plate LXI.) was constructed on the west branch of the Croton River, to form a storage reservoir having a capacity of 2,722,720,000 gallons for the city of New York. The reservoir has a surface of 279 acres, the maximum depth of the water being 57 feet. The general dimensions of the dam are: Length on top; « « *» « « * « » » « «* Gyeoteet. “at level of the river, . . . . + « - 200.0 ‘“ Maximum height above foundation,. . . . . 780 ‘§ Width at top,- . 2. «© s 28 # © © © 2 8.6 «¢ aS Ch Dasey, Ge Rah ee CA a ow Je te ae SO Plate LXI. shows the profile of the dam as designed by the Chief Engineer, Geo. S. Greene. It was built with cut-stone facings, and a hearting of concrete into which large stones were placed from the base to. 15 feet above the stream. The concrete was mixed in the proportion of 4 parts of stone, 2 of sand and 1 of cement. It weighed 133} pounds per cubic foot. Water is drawn from the reservoir by means of a tower having two 36-inch outlet-pipes which pass through the dam. The overflow is about 100 feet long, and was formed by excavating the rock at the north-east end of the dam. The work was done originally under the direction of “The Croton Aqueduct Board.” However, in 1870, when the dam was almost completed, the control of the work was transferred to the Department of Public Works. The new authorities changed the plans by building against the up-stream face of the dam an earthen bank 20 feet wide on top and having a slope of 5 to 2. According to Mr. J. J. R. Croes, the engineer in charge of the construction of the dam, this embankment was built of porous material which would not puddle well. “It was built by contract, and not rolled or thoroughly rammed, but merely carted over.” Under these circumstances the earthen embankment must have become saturated, sub- jecting thereby the dam to an increased pressure instead of reinforcing it. The work was commenced in September, 1866, and completed in the fall of 1872. The masonry dam contains about 21,000 cubic yards of concrete and 6000 cubic yards of cut stone. The Bridgeport Dam+ (Plate LXII.). This dam was built across the Mill River at a point 54 miles from Bridgeport, to form a new storage reservoir for the water-supply of that town. The general dimensions of the dam are: Length on top, « © 6 4 2 © » @ s « » @ ww » GdOteet, at bottom of stream, . . . . ..... 50 Maximum height, . . . .. 0.0. 6. © «2 es 40 & The west end of the dam forms an overflow-weir 80 feet long, being 5 feet below the guard-wall. * See “Memoir on the Construction of a Masonry Dam,” by J. J. R. Croes, C.E., in the Papers of he: American Society of Civil Engineers for 1874. + Enguneering News, April 9, 1897. AMERICAN DAMS. 129 The scouring-gallery is 3 feet 4 inches by 3 feet 4 inches in the clear, and is closed by a suitable gate, which is operated by worm gearing. A gate-chamber 10 feet by 15 feet in the clear, lined with 12 inches of brick, is built against the dam, the back of which forms one side of the chamber. The other sides consist of rubble walls 7 feet thick at the base and 3 feet at the top. The chamber is divided into two partitions by means of two walls, projecting 2 feet 10 inches, between which a fish-screen is placed. Three openings, 30 inches in diameter and located at different heights, serve as the inlet to the gate-cchamber. Each opening is provided with a suitable gate. After passing through the screen, the water is drawn from the reservoir by means of a 30- inch cast-iron outlet-pipe, having a stop-cock in the gate-chamber. The wall was founded entirely on rock, and was built of rubble masonry made of gneiss rock and hydraulic mortar consisting of I part of Rosendale cement to 2 parts of sand. The area of the reservoir is about 60 acres, and its capacity, 240,000,000 gallons. The original plan was of the Krantz type, as indicated by the dotted line in Plate LVI.; the dam was built, however, in steps, as shown. When the reservoir was first filled, the dam proved to be very pervious, and it has therefore been proposed to build an earthen embankment of 50 feet base at the lowest point of the valley and extending within 10 feet of the overflow against the up-stream face of the wall. Messrs. Hull and Palmer are the engineers who designed and executed this work. The Wigwam Dam,* Plate LXIII, was built in 1893 to 1903 to form a storage reser- voir of 735,000,000 gallons capacity for the water-supply of the city of Waterbury, Connecticut. The watershed supplying the reservoir contains 18 square miles. The dam is located at the junction of the West Branch of the Naugatuck River with Fern Brook. The valley at this point is only 80 feet wide at the bottom and 600 feet at 75 feet above the river-bed. The dam is founded entirely on rock. Its central part is curved to a radius of 600 feet on a chord of 391 feet, and the ends, which are only under a pressure of 20 feet of water, are made straight on the extension of the chord of the curved part. The dam has a maximum height of 91 feet above the foundation. The top width is 12 feet. The body of the dam is formed of rubble masonry, which is faced on both sides with broken ashlar of granite averaging 30 inches in thickness. The facing stones are set normal to the line of pressure. The foundation courses are laid with Portland-cement concrete, mixed 2:1, but for the remainder of the masonry Rosendale cement mortar, mixed 2:1, was used. Water is drawn from the reservoir through two 30-inch cast-iron outlet-pipes that pass through the dam. The flow through these pipes is regulated in a gate-house that is built in the up-stream side of the dam. This gate-house is divided into two compartments, or wells, one for each pipe-line. Each compartment has an inlet at its bottom, 55 feet below the flow-line of the reservoir. Higher inlets are provided 11 feet apart and are alternated between the compartments. Each of the wells can be drained out into the old brook channel. Vertical screens, 5 feet wide, of copper wire in wood frames extend from the top to the bottom of each well. At the down-stream end of the outlet-pipes a gate- * Engineering News, May 7, 1903. 130 DESIGN AND CONSTRUCTION OF MASONRY DAMS. house is placed, where either pipe-line or both may be used to supply the 36-inch pipe- line leading to the city. Immediately below the gate-house a 36-inch Venturi meter is placed for recording the water supplied to the city. At the north end of the dam a waste-weir 82 feet long was made by cutting down the rocky hillside and building a wall 5 feet high and 4 feet wide as a continuation of the main dam. The roadway which is formed on top of the dam is carried over this spillvay by means of three masonry arches supported by piers built in the waste-weir. The construction was begun in the spring of 1893 and all work done that year was by the day. In the winter of 1893-4 contracts were let for completing all work required to impound water to a level of 15 feet below the flow-line adopted for a full reservoir. These contracts were executed and a regular supply was furnished in January 1896. In Igo1—o2z the dam was built up to the full height contemplated in the plans. In addition to the masonry dam an earth dam with a concrete core-wall was constructed at a depression known as the South Gap, to retain the water in the reservoir. It has a maximum height of 35 feet and a length of 600 feet. At the north end of this dam an overflow 1,170 feet long was made in rock. The top of the earth dam is 9 feet above this spillway and 24 feet above the crest of the masonry dam. . The works were planned and executed under the direction of R. A. Cairns, M. Am. Soc. C. E., City Engineer of Waterbury. The San Mateo Dam* (Plate LXIV) was built in 1887 and 1888 near San Mateo, California, to form a storage reservoir for the water-supply of San Francisco. This reservoir has covered the old Crystal Springs reservoir from which the city was formerly supplied. The plans originally contemplated building a masonry dam 170 feet high which would store about 31,000,000,000 U. S. gallons. The top-width of the dam was to be 25 feet. At present the dam has only been carried up to a height of 146 feet, as the storage thus obtained is sufficient for the present demand. Its greatest bottom- width is 176 feet. The dam has been curved up-stream to a radius of 637 feet. At the 170-foot level it will have a length of 680 feet. As no rock suitable for rubble masonry could be found in the vicinity of the work the dam has been entirely built of concrete made with Portland cement mortar, mixed in the following proportions: 22 cubic feet of broken stone, one barrel of Portland cement, and two barrels of sand. The stone used was quarried in small nodules, which were frequently covered with clay and serpentine. It was crushed by machinery and passed through revolving iron cylinders, where it was thoroughly washed by jets of water. All the sand required for the masonry had to be brought from the dunes of North Beach near San Francisco, a distance of about 32 miles. It was first trans- ported in cars a distance of about a mile to barges, towed up the bay for a distance of about 25 miles to a landing opposite San Mateo, and then hauled in wagons to the dam for a distance of. 6 miles. The concrete was mixed in six cubical iron boxes revolved by steam, and was delivered to the work in small cars which were pushed by hand over a double-track tramway. At the dam the tramway was carried on a trestle, built at the top level of the wall, and carried half-way across the valley. The concrete was delivered to * Eighteenth Annual Report of the U. S. Geological Survey, Part IV. PLATE I, San Mateo Dam. Roughening Surface of Concrete Blocks to Receive Fresh Cement. (From ‘* Eighteenth Annual Report of U. S. Geological Survey.”) PLATE J. BEAR VALLEY Dam. (From “ Eighteenth Annual Report U.S. Geological Survey.’’) AMERICAN DAMS. 135 platforms on the wall through vertical pipes, 16 inches in diameter, which were placed at intervals between the rails of the track. The height from which the concrete was dropped was at times as much as 120 feet, but no injury was done. The concrete was placed in the dam in large moulds, forming blocks that contained from 200 to 3co0 cubic feet. These blocks had numerous offsets and were dovetailed together in an ingenious manner. They have been so well bonded in every direction that the dam forms almost a monolith. Since the reservoir has been filled the only signs of any leakage have been a few damp spots in the front face. The outlet from the reservoir consists of a 54-inch riveted iron pipe, which is laid in a rock tunnel 390 feet long, which was driven through a hill on the north side of the channel. This tunnel is lined throughout with 4 courses of brick and is 7} feet high by 74 feet. wide inside of the lining. A brick-lined shaft 14 feet in inner diameter, placed in the reservoir just inside of the dam, intersects the tunnel. Inside of this shaft there is a stand-pipe connecting with the main outlet-pipe. Three branch tunnels are driven from the shaft at different elevations to the reservoir. In each of these branch tunnels a Pipe, controlled in the shaft by a gate-valve, is laid and connected with the stand-pipe. The ends of the tunnels under water have plain cover-valves over elbows and are provided with fish-screens that are put into position from floating barges. A 44-inch pipe is laid from the outlet-pipe to San Francisco. The Bear Valley Dam (Plate LXV) was constructed in 1884 in the Bernardino Mountains in California to form a large reservoir for irrigation purposes. As all the cement, tools, and supplies had to be hauled for about 7o miles over rough mountain roads to the site of the dam, and the available financial means were very restricted, the engineer in charge of the work, F. E. Brown, C.E., designed a structure which surpasses in boldness all other dams built. The profile adopted is so thin that the dam cannot resist the thrust of the water by gravity. It owes its stability solely to the curved form of its plan, which enables the wall to act as an arch. Assuming the weight of the masonry at 166.7 pounds per cubic foot (corresponding to a specific gravity of 2%) we find that the line of pressure, reservoir full, lies almost entirely outside of the profile. The work was commenced in the summer of 1883 by the construction of an earthen dam, 6 feet high, about 24 miles above the site selected for the masonry dam. This dam retained all the water in the stream during the construction, causing it to overflow about 450 acres of land. The masonry dam was built during the latter half of 1884. It was founded on rock and constructed of a rough granite ashlar with a hearting of rubble, all laid in Portland-cement mortar or grout. A barrel of this cement delivered at the dam cost $14 to $15, of which amount $10 was for haulage. The dam is curved up-stream with a radius of 335 feet, and is about 3co feet long on the crest. Its maximum height is 64 feet. The masonry was carefully laid, the leakage through the dam, when the reservoir was filled, amounting only to a sweating. The outlet from the reservoir is controlled by a 20X24-inch iron sluice-gate which lets the water into a 2X3-foot culvert built in the bed-rock. The sluice-gate is operated from the top of the dam by a stem passing through a 6-inch vertical pipe. A waste-weir, 20 feet wide, was excavated in the rock at the south end of the dam 136 DESIGN AND CONSTRUCTION OF MASONRY DAMS. to a depth of 8.5 feet below the level of the crest of the dam. It is provided with flash- boards. The amount of water stored in the reservoir is 1,742,400,000 cubic feet. It is supplied by a watershed of about 56 square miles. The irrigation company which built the dam intended to replace this rather dangerous structure by a more substantial rock-filled dam, to be built about 200 feet farther down- stream. This dam was to have a height of 80 feet. Its foundation was laid in 1893, but rothing more was done in the construction. The Sweetwater Dam (Plate LXVI).—This dam-was constructed in San Diego County California, by the San Diego Land and Town Company, for storing water for irrigating large tracts of land and for supplying water to’ National City. The flow of the Sweetwater River, from which water was to be impounded, varies from 1 to 2 cubic feet per second during the dry seisons of the year to tooo cubic feet per second during periods of freshets. The construction of the dam and reservoir was decided upon in November, 1886. According to the original plans, the wall was to be formed of concrete and to be 10 feet thick at the base, 3 feet thick at the top, and 50 feet high. On the up-stream side of this concrete dam an earthen bank was to be constructed. After about two months’ work had been done Mr. James D. Schuyler, C.E., was given charge of the construction, and wisely modified the plans by deciding to build a substantial dam of rubble masonry, instead of a concrete wall reinforced by an earthen bank. Owing to the great need of water, the dam was at first carried up to a height of 60 feet, with a profile shown by the dotted lines in Plate LXII. The reservoir thus formed had a storage capacity of -1,221,000,000 gallons. Subsequently the dam was built to a height of 98 feet, increasing the capacity of the reservoir to 5,882,000,090 gallons. The profile adopted is shown by the full lines in Plate LXII. The principal dimensions of the dam are: ‘Lensth at tof. % « #4 9 & 4. @ 2 2-2 & © & BRe test Fleiohite. Sloe. Bie. te wie vee GS eee “Ga GS OOO Width at tops. is, Gal Ge ph ee eh eet aa!) ne es. my 1D Ca ED “ES Widthat base, a a ee a we we a a we ee The up-stream face is carried up to within 6 feet of the top of the dam with a batter of 1in6. The batter of the down-stream face starts at the base with 1 in 3 for 28 feet, changes then to 1 in 4 for 32 feet, and remains then 1 in 6 to the coping. The plan is curved, the radius at the top of the up-stream face being 222 feet. Con- siderable reliance was placed upon the additional strength obtained by curving the plan, as the line of pressure, reservoir full, would be only one sixth the width of the base from its down-stream toe, if the dam resisted simply by gravity. The dam was founded on solid rock, which was carefully prepared for the masonry. The stone used was dark blue and gray metamorphic rock, impregnated with iron. It weighed about 175-200 Ibs. per cubic foot. The quarry was about 800 feet down-stream from the dam. Portland cement of the best quality was used. It was mixed with clear, sharp river sand in a revolving, square iron box. The usual proportion for the mortar was I part of cement to 3 parts of sand; but for the masonry near the up-stream face of the dam only 2 PLATE i. SWEETWATER DAM.—INCREASING THE HEIGHT OF THE PARAPET. (From “ Eighteenth Annual Report U.S, Geological Survey."’) y AMERICAN DAMS. 139 measures of sand were mixed with 1 of cement. The masonry weighed about 164 lbs. per cubic foot. It wasall laid by means of four derricks, worked by horse-power. Water is drawn from the reservoir by means of an inlet-tower, which is located 50 feet up-stream from the dam. It has seven inlet-valves, which are placed at different elevations. Three outlet-pipes, respectively 14”, 18”, and 36” in diameter, lead from the tower. They have gates on the down-stream side of the dam, by means of which the flow from the reservoir can be regulated. The waste-weir is formed by part of the dam. It is 4o feet long and 5 feet deep. By means of piers, it is divided into 8 bays. The weir is calculated to discharge 1500 cubic feet of water per second. There is also a 30-inch blow-off pipe, which can discharge 300 cubic feet of water per second. The Sweetwater Dam was finished April 7, 1888, the construction having required 16 |months’ time. The amount of masonry laid, including that in the inlet-tower, waste-weir, etc., was 20,507 cubic vards. The average amount of cement used was 1 barrel of cement to 1.17 cubic yards of masonry. The total cost of the work, which was constructed at a time when wages were very high in California, was $234,074, not including the cost of the land. We have taken the above description from the very complete and interesting paper on the Sweetwater Dam by Mr. James D. Schuyler, the engineer in charge of the work, which paper was read before the American Society of Civil Engineers on October 17, 1888. Since the above account was written, the dam has been subjected to a very severe test during a flood caused by a rainfall of 6 inches in 24 hours. For 40 hours a sheet of water, 22 inches higher than the top of the parapet, flowed over the dam. The masonry of the dam withstood the strains it had to bear very successfully, not a stone being displaced, but great damage was caused to the outlet-pipes by the erosion of the water below the dam. The repairs required and some changes in the construction of the dam which were deemed advisable cost about $30,000. The alterations made in the dam were as follows:* 1. The parapet of the dam was raised 2 feet and strengthened so as to be able to hold the water permanently level with its crest. For 200 feet, however, the parapet was kept 2 feet lower so as to form a waste-weir, which was provided with iron frames for flashboards, by means of which the waste-weir can be raised to the level of the other part of the parapet. The effect of this change has been to raise the high-water level in the reservoir 5.5 feet, which adds 25 per cent to the capacity of the reservoir. 2. The original spillway was extended by adding four more bays, each 5 feet wide. All of the bays were carried up to the new crest of the dam. 3. An unused tunnel, 8 x 12 feet in size, which had been excavated to draw down the water in the reservoir during a lawsuit about some of the land required for the reservoir, was utilized as an additional wasteway by placing two 48-inch and two 30-inch pipes in it. These pipes pass through a masonry bulkhead which was built in the tunnel at the reservoir. They are controlled by gate-valves placed in a shaft which reaches the surface. 4. The face of the rock slopes below the waste-channel from the overflow was covered with a grillage of iron rails embedded in concrete. * Eighteenth Annual Report of the id. S, Geological Survey, Part IV. 140 DESIGN AND CONSTRUCTION OF MASONRY DAMS. 5. A concrete wall, 15 feet high, was built 50 feet down-stream from the dam and concentric therewith, in order to form a pond 5 to 10 feet deep which acts as a water-cushion for the overflow. 6. The main supply-pipe was replaced and protected through the canyon by means of concrete collars and spur-walls. The profile of the Sweetwater Dam, while not as slender as those of the Zola and Bear Valley dams, is much bolder than the types now usually adopted. During the flood mentioned above, the line of resistance, though still within the profile, was within a few feet of the outer toe. This must have caused some tension in the masonry at the up-stream face. The safety of the dam has doubtless been due to the excellent manner in which it was built and to the additional strength obtained by building it curved in plan. | The La Grange Dam$* (called also the Turloch Dam), Fig. 33, was built in 1891-94 across the Tuolumne River, in California, to form a weir to divert water from the river into two canals which begin at the dam, one on each side of the valley. It was constructed in a narrow canyon that is only 80 feet wide at the level of the river-bed. The dam is i Radius=300 ft. Fic. 33.—La GrancEe Dam. 125 feet high at the up-stream face and 129 feet high above the down-stream toe. The dam is curved in plan to a radius of 300 feet. Its top and bottom widths are respectively *The descriptions marked “S” are taken principally from ‘‘Reservoirs for Irrigation, Water-power, and Domestic Water-supply,” by James D. Schuyler, M. Am. Soc. C. E. AMERICAN DAMS. 140 24 and go feet. The whole dam, which has a length of 310 feet on the crest, acts as an overflow-weir. During floods 46,o00 cubic feet of water per second, corresponding to a depth of 12 feet of water on the crest, has passed over the dam. As no storage was contemplated, the dam is not provided with pipes. The canyon back of the dam will be allowed to fill with deposit. The dam was built of rubble masonry laid in Portland-cement concrete. A subsidiary dam, 20 feet high and 120 feet long, was built about 200 feet below the main dam to form a pond 15 feet deep at the main dam, which acts as a water- cushion for the overflow. The dam, which is the highest overflow-weir built to the present time, was designed by Luther Wagoner, C.E., and was built under the d:rection of E. H. Barton, engineer of the Turlock irrigation district, H. S. Crowe being in immediate charge of the work. The Folsom Dam (Fig. 34) was built in 1886-91 across the American River, in California, to furnish water-power and, also, to divert part of the river to the plains of the Sacramento Valley for irrigation. All of the work was performed by convict labor from one of the State prisons of California. The dam was constructed at the top of a natural fall in the rock, and is 98 feet high on the down-stream face and only 69.5 feet high at the upper face. It is 87 feet thick at the base and 24 feet at the crest. This dam is about the only one of the struc- CROSS SECTION OF WEIR Fic. 34.—Foitsom Dam. tures of this kind erected in the Western States which is not curved in plan. It crosses the river on a straight line and is only curved where it joins the side-wall of the diversion canal. The whole length on top, including the curved part at the canal, is 650 feet. An overflow-weir 6X180 feet is formed in the centre of the dam. It can be closed by a single movable shutter consisting of a Pratt truss backed with wood, which is operated by means of hydraulic jacks. The masonry consists of rough granite ashlar, composed of large blocks weighing 142 DESIGN AND CONSTRUCTION OF MASONRY DAMS. io tons or more, laid in Portland-cement mortar. The dam proper contains about 48,590 cubic yards of masonry. The Hemmet Dam® (Plate LXVIJ) was built across the south fork of the San Jacinto River, in California, to form a reservoir for irrigation purposes. The enterprise was projected in 1886, but the work on the dam was not begun until January, 1891. According to the original plans the dam was to reach a height of 150 feet above the creek-bed. It was determined, however, to stop the wall, for the present, at an elevation of 122.5 feet, to which height it was brought by the fall of 1895, after various delays caused by freshets. The height above the lowest foundation is 135.5 feet. The dam was built up to an eleva- tion of 110 feet according to the profile designed for a 150-foot dam. At this level, where the dam has a thickness of 30 feet, an offset of 18 feet was made from the front face, and the dam was then carried up 12.5 feet higher, so as to make the top-width 1o feet. Below the 110-foot level the front and back faces are sloped respectively 5 in ro and 1 in ro. The bottom-width is 1oo feet. The lengths of the wall on top and at the bottom of the valley are respectively 280 and 4o feet. The dam is curved in plan to a radius of 225.4 feet. A notch, 1X50 feet, was left in the wall to act as a waste-weir, but during severe freshets the water overflows the whole dam. The dam containse 31,105 cubic yards of granite rubble masonry. The large stones were placed at least 6 inches apart, the spaces between them being filled with concrete made with Portland-cement mortar in the following proportions, viz.: x part cement, 3 parts sand, and 6 parts stone crushed to pass through a 24-inch ring. The mortar and concrete were mixed in iron boxes revolved by water-power. All the cement used in the dam (about 20,000 barrels) had to be hauled for 23 miles up the mountain to an elevation of 500 to 600 feet, over grades of about 18 per cent. The cost of a barrel of cement delivered on the ground was about $5.00. Two 22-inch pipes (respectively at the 45- and 75-foot levels) form the outlet from the reservoir. Their up-stream ends are turned upwards by elbows and flared to 30 inches in diameter. The pipes can be closed in the reservoir by hemispherical covers operated by wire ropes, each passing over a pulley and windlass on top of the dam, but the covers are usually raised and replaced by fish-screens, the outlet-pipes being controlled by stop-cocks set below the dam. The Colorado Dam* (Plate LXVIII.) was constructed in 1891-92 across the Colorado River, about two miles above Austin, to furnish power for pumping that city’s water-supply, for electric lighting, for propelling street cars, and for general manufacturing purposes. At the site selected for the dam, the river flows in a deep gorge in limestone, with bluffs on either side rising as high as 150 feet. The dam was founded on the rock forming the river-bed, which was only excavated at the faces of the wall, to a depth of about 4 feet. It was constructed entirely of masonry, the faces and the coping being formed of blue granite that was quarried in Bennet County, Texas, at * See Engineering News, July 11, 1891. See Report on the Austin (Colorado) Dam by J T. Fanning, Con- sulting Engineer, June 22, 1892. AMERICAN DAMS. 143 a distance of 80 miles from the work, the balance of the dam being built of rubble masonry, composed of hard limestone, obtained at the site of the dam, and of hydraulic mortar composed of I part Portland cement to 3 parts of sand. The coping stones were fastened by iron dowels and clamps. The masonry laid in the dam amounted to about 18,000 cubic yards of granite cut stone and about 70,000 cubic yards of limestone rubble, the price paid for the former class of masonry being $11—$15, and for the latter $3.60 per cubic yard. Fifty cents additional price per cubic yard was paid where Portland cement was used. Including the bulkheads, at either side, the length of the dam is 1275 feet, of which 1125 feet form the overflow-weir. The water-shed above the dam contains about 50,000 square miles, from which a maximum quantity of water of about 250,000 cubic feet per second flows over the dam. The lake formed by the dam is 25 miles long. A canal 90 feet wide and 15 feet deep conveys the water to the turbine-wheels. The power obtained is estimated at 14,636 H.P. for 60 working hours per week, of which 720 H.P. are required for pumping the city’s water-supply. The cost of the dam was about $570,000, and the cost of the entire work, including dam, power-house, reservoir and distributing system, was about $1,400,000. The whole cost was borne by the city of Austin. The works were designed and constructed under Mr. Joseph Frizzell, Chief Engineer, and Mr. John Bogart and Mr. J. T. Fanning, Consulting Engineers. The dam failed on April 7, 1900, after a severe rainstorm. Five inches of rain fell. Failure of the Colorado Dam at Austin, Texas.*—A heavy rainfall of 5 inches fell in Austin and vicinity from 1 p.m. on April 6th to 4 4.M. on April 7th, 1900, in a moun- tainous country and on ground that was already saturated. Tremendous rains fell, also, along the Colorado and its tributaries for a distance of 100 miles above Austin, The river rose rapidly, and by 11.20 A.M. on April 7th it reached a level of 11.07 feet above the top of the dam, 1.27 feet above the highest previous flood-level. The dam gave way at a point about 300 feet from its east end. The current pushed its way through the gap that was made and shoved two sections of the dam, one on each side of the gap, and each about 250 feet long, bodily about 60 feet down-stream, without the slightest overturning, leaving them almost parallel with their original position. Forty minutes after the break the western section of the dam that had been shoved forwards and part of the eastern section turned over towards the dam and disappeared beneath the torrent. The remaining portion of the eastern section of the dam was swept away during the succeeding night. The failure of the dam appears to have been due to sliding, made possible by the fact that the down-stream toe of the dam was being undermined by the water flowing over the dam and by a steady stream from the power-house, which flowed in a canal (tail-race) along the toe of the dam to the channel of the river. This location of the tail-race from * The Austin Dam, by Thomas U. Taylor, Paper No. 40 of Water-supply and Irrigation Papers of the U. S. Geological Survev. 144 DESIGN AND CONSTRUCTION OF MASONRY DAMS. the power-house was very faulty and contrary to the plan of the first chief engineer, Mr. J. P. Frizell, who resigned early in 1892, as the Board of Public Works, under whose direction the dam was built, interfered much in the engineering questions involved. The foundation on which the dam was built was very poor in places. For the first 150 feet from the eastern bluff a good rock foundation was obtained, but at this point a fault 75 feet wide, extending to an indefinite depth, filled with adobe, or pulverized drock, with an occasional streak of red clay, was encountered. The excavation in this space was carried down 8 or I0 feet in the up-stream trench, which was widened from 4 feet to 10-15 feet. The dam was given an additional protection opposite the fault by dumping clay along its. up-stream face. From the west end of the fault the rock was of poor quality for 350 feet, but for the remaining part of the dam a hard stratum of limestone was obtained asa foundation. At the site selected for the dam the formation consists of alternate hard and soft strata of lime- stone, the latter being so soft that the material can be excavated with a pick and a shovel. As already stated, the western part of the dam was founded on a hard stratum of limestone. During a freshet in 1892, however, the water flowing over the dam cut through the hard stratum and tore up large pieces of rock, some weighing 7-8 tons, and deposited them 150-200 yards down-stream. A much better site than the one selected could have been found in the plateau country, I to 2 miles up-stream from Austin, where the formation consists of hard limestone in horizontal strata. Such a site would have included certain other advantages and was advocated by Mr. Frizell, who was, however, overruled by the Board of Public Works, which wished to have the dam near Austin. Mr. Frizell appears to have fully realized the danger to which the dam might be exposed from erosion. His plans contemplated an extension of the massive apron of the dam by a bed of concrete, to be applied as soon as necessary. After he had resigned as. chief engineer, Mr. Frizell addressed a letter to the Mayor of Austin on April 8, 1896,—four years before the dam failed,—calling his attention to the dangerous abrasion that might occur 300-400 feet from the east end. From what has been stated above the causes of the failure of the Austin dam are very evident, viz.: first, a poor foundation, and, second, insufficient protection against the erosive action of the water at the down-stream face. If the Board of Public Works in charge of the construction had listened to the advice of its engineers this failure would probably not have had to be recorded. The Dam of the Butte City Water Company** was constructed in 1893-95 across. Basin Creek to form a reservoir for the water-supply of Butte City, Mont. The dam is located about sg00 fect above the level of the sea in a region where there is practically no rain, the reservoir being filled by melting snow. Its principal dimen- sions were to be, according to the adopted plans: * Engineering News, December 17, 1892, August 7, 1893, and September 5, 1895. AMERICAN DAMS. 145 DOP Wide: assseanl dues ae nee eineksbecesedonsenawenes 10 feet. BottOmewidths i sie sedis eels ee vie Hare wee ok eee Sees aa. Maximum heieht: «cs seceucigecytiebie eek os seeesaacee 120‘ Length On: 1Op..s2aaeeiees enc eeuaeeee cata aa tnensan 350“ Radius Of plans..:sa00 esac ede se akeeee ek eke eke oe eee 350 «CSS Length Of wasteweltin cis sigicsesed wad Heese ote ge ig, The reservoir was to have an area of 130 acres and a capacity of 1,000,000,000 U. S. gallons. The dam has only been built up, thus far, to a level 4o fect below the projected crest. It is at present 88 feet high and stores about 200,0c0,0co gallons. The dam was constructed of large stones placed in concrete (made of crushed granite and Yankton Portland-cement mortar), faced with hard blue granite. A 20-inch waste-pipe and two 20-inch supply-pipes pass through the masonry. The water is conveyed from the dam to the city by a banded, red-wood stave pipe, 24 inches in diameter, 9 miles long, and, then, by a lap-welded 20-inch steel pipe 3 miles long. The works were designed by Mr. Chester B. Davis, M. Am. Soc. C. E., and was constructed under the direction of Eugene Carroll, the Chief Engineer of the Water Company. The Sodom Dam (Plate LXIX) was constructed in 1888-1893 to form a new storage reservoir for the water-supply of the city of New York. The work was performed under the direction of the Aqueduct Commissioners (who were given charge of the construction of the New Croton Works by Chapter 490 of the Laws of 1883), Mr. A. Fteley being Chief Engineer. The Sodom Reservoir and the Bog Brook Reservoir form together what is known as the “ Double Reservoir 1” on the East Branch of the Croton River. While these two basins have about equal storage capacities, the water-shed of the former is about twenty times as large as that of tbe latter, the areas of the water-sheds being respectively 73.42 and 3.5 square miles. To compensate for this difference, the two. basins are united by a tunnel 10 feet in diameter and 2000 feet long. The storage capacity of the double reservoir I is about 9,500,000,000 gallons. The Sodom Reservoir is formed by a masonry dam, built across the East Branch of the Croton River, and by an earthen bank about 9 feet high and 600 feet long, constructed nearly at right angles to the masonry structure on a ridge to the east of it. The earthen dam is continued by a masonry overflow-wall about 8 feet high and s90 feet long, its top being at an elevation of about 415 feet above mean tide in the Hudson River at Sing Sing. The principal dimensions of the masonry dam are as follows: Length at coping, . « 2 & » 2 « « « «© » » = $00 Teet Maximum height above foundation, . 2. . « « « »« 98 * “ “« ground, «© «© * « 2 « « « 78 * JTop-width, << « @ & 9 486 a a eae ew ee Te Width at foundation, . 2. o © « « «© « «© «© «© «» 5§3 ® 146 DESIGN AND CONSTRUCTION OF MASONRY DAMS. The total amount of masonry placed in the structure was 35,887 cubic yards. Near the centre of the dam a gate-house, 37 feet by 42 feet, was built for controlling the flow from the reservoir, which takes place through two 48-inch cast-iron pipes. The masonry was laid with the utmost care. The foundation, which was through. cut solid rock, was swept with wire stable-brooms and washed clean by means oh streams from hose-pipes. The irregularities of the bed-rock were generally levelled by layers of concrete made with Portland cement. Where water issued from cracks in the rocks, however, better results were obtained by laying rubble made of small stones, by which the water was confined to small wells about 2 feet in diameter. When the mortar of the rubble masonry had set sufficiently, the wells were bailed out and quickly filled with dry mortar into which large rubble stones were bedded. The mortar consisted principally of Portland cement and sand, mixed 1 to 2 in the lower and upper parts of the wall and 1 to 3 in the middle part. An interesting feature of the construction of the Sodom Dam was the use of a steel cable, 2 inches in diameter and weighing 7 lbs. per foot, which was stretched across the valley and served for delivering. the building materials on the wall. The cable was stretched across two towers, 667 feet apart, and anchored into the bed- rock. For a full description of the details of the construction of the Sodom Dam we refer the reader to a paper on this subject written by Mr. Walter McCulloh, M. Am. Soc. C. E. and published in the transactions of the American Society of Civil Engineers for March 1893. Owing to the great care taken in laying the masonry in the Sodom Dam, this structure has proved to be perfectly water-tight. In this connection we quote the following remarks from the paper just mentioned: “As to the water-tightness of Sodom Dam, it is perfect. When the reservoir is filled (with 68 feet of water behind the wall) many careful examinations have failed to disclose any leaks whatever, either through the wall or under it, or through the rock around the ends in the side hill. ‘Sweating’ at the joints in the facing stone appears at several points only, but not in sufficient quantity to produce a trickle. What moisture there is will wholly disappear on a dry, clear day; but if the day ‘e humid, dampness is visible upon the face of the stone as well as at the joints.” The contract for the Sodom Dam and its appurtenances was awarded to Sullivan, Rider & Dougherty on December 30, 1887. Ground was broken on February 22, 1888. Owing to various delays the work was not finished and finally accepted by the Aqueduct Commissioners until October 31, 1892. The engineers in immediate charge of the work under the directions of the Chief Engineer were Mr. George B. Burbank, Division Engineer, and Mr. Walter McCulloh, Assistant Engineer. On the resignation of the former, June 17, 1891, the latter was appointed Division Engineer and had charge of the work to its completion. The Titicus Dam (Plates LXX. to LXXVI.) was constructed in 1890 to 1895 across the Titicus River, an affluent of the Croton, near the village of Purdy’s Station, N. Y., to form a storage reservoir for the water-supply of the city of New York. The dam consists of a central wall of masonry which is extended on each side PLATE L.. SODOM DAM, IN CONSTRUCTION. PLATE M. TITICUS DAM, FRONT FACE. TITICUS DAM, BACK FACE, AMERICAN DAMS. 151 by an earthen dam. The central masonry structure, part of which forms the overflow- weir, has a length of 534 feet. The lengths of the north and south earthen dams are respectively 732 and 253 feet, the whole length of the dam being 1519 feet. The masonry portion of the dam was founded entirely on rock. The earthen dams were provided’ with masonry core-walls which were founded on hard-pan with the exception of a short distance on both sides of the masonry dam, where a rock foundation was obtained. The principal dimensions of the masonry dam are: Width undef coping, « « « =. « « » « «= » » B07 feet. Width about 109 feet below coping, . . . . . « 75.2 § Maximum height above foundation, . . . . ». . 135.0 ‘ Maximum height above surface,. . . . . . . . 1090 “ The waste-weir or overfall, which has a length of 200 feet, is built according to the stepped profile shown on Plate LXXIV. The masonry consists of rubble, faced up-stream and down-stream with cut stone, laid in regular courses. The bulk of the rubble is composed of large stones, containing 3 to 30 cubic feet, the spaces between them being filled with mortar, into which small stones are bedded. The cornice of the dam, the top of the overflow, and the superstructure of the gate-house are constructed of granite dimension-stone. All the stone required for the dam was obtained from a quarry situated about 14 miles from the work. It was transported on a tramway, partly by gravity and partly by means of a_ small locomotive. Both American and Portland cement were used for the mortar, which was usually composed of I part cement to 2 parts of sand. Part of the masonry was laid during freezing weather, the mortar being mixed with brine and the sand heated. The stones were steamed before being laid. No masonry was laid, however, when the temperature was below 20° Fahrenheit. Thirty-six masons with six derricks were usually employed on the wall. They laid on an average 3240 cubic yards of masonry per month and a maximum of 5700 cubic yards. The earthen dam, constructed on both sides of the masonry structure, has a maximum height of 102 feet above the surface and rises 9 feet above the crest of the overflow-weir It has a top-width of 30 feet and slopes of about 2% to 1. The up-stream face is covered with a paving of stones (18 inches deep, laid on 12 inches of broken stone) which extends 5 feet above the top of the overflow. The top of the dam, the down-stream slope, and the up-stream slope above the paving are sodded. The core-wall, which is constructed of rubble masonry, is 5 feet wide on top, and 17 feet wide at a depth of 98 feet, both faces being battered about .06 foot per foot. Below this depth both faces are vertical. The core-wall has a maximum height of 124 feet above the foundation. The flow from the reservoir is regulated by a gate-house, which is constructed. 152 DESIGN AND CONSTRUCTION OF MASONRY DAMS. on the up-stream face of the dam, near the overflow-weir. A central wall divides the substructure of the gate-house into two divisions, each of which is divided by a cross-wall into an inlet and an outlet water-chamber. The former has three inlet openings (6 feet wide and 8 to of feet high): one at the surface of the reservoir, one at mid-depth, and one at the bottom. These openings are protected by screens made of 4X 2$-inch iron. They can be closed by means of stop-planks or wooden drop-gates which are placed in grooves provided in the side-walls of the substructure. There are two sets of grooves, 2 feet 5 inches apart. By placing stop-planks in them and filling the intervening space with a puddle of clay and earth a tight coffer- dam can be built which cuts off the gate-house securely from the reservoir. In ordinary cases one set of stop-planks suffices for this purpose, if the joints are properly calked. The cross-wall between each inlet and outlet chamber has two openings (one at the bottom and one at mid-depth) which are controlled by 2 X 5-foot sluice-gates, operated from the floor of the gate-house. The top of the cross-wall forms an overflow- weir, the height of which can be regulated by means of stop-planks. Two sets of grooves are provided in the side-walls for these stop-planks, as at the inlet openings. Two 48-inch outlet-pipes (one for each division of the gate-house) convey the water from the outlet-chambers to the old channel of the Titicus River, which was excavated to rock for a short distance. Each of the lines of outlet-pipes is controlled by a stop-cock placed in a vault about 80 feet below the gate-house. Besides these pipes, a 24-inch drainage-pipe, that was used during the construction of the reservoir, passes through the dam. Its up-stream end is closed by a flap-valve. The superstructure of the gate-house is 32 feet 6 inches X 35 feet in plan. It is constructed of granite and has a roof of brick arches sprung from I beams. The floor of the building consists of a cast-iron grating supported by I beams. Before the work on the dam was commenced, the Titicus River was diverted by building a crib-dam about 1000 feet above the site of the masonry dam. 0 ae Gr (d+d)a we find, by reducing, a’ — rad — bar=o. The next courses of the dam were determined by using Equations (2), (3), (4) and (6) to elevation 96, which is at a depth of 110 feet below the surface of the water. It was decided to give one batter to each face of the dam from this elevation to the base, where the limiting pressure should equal 15 tons of 2000 lbs., both for reservoir full and empty. The gravel resting on the dam below the river-bed complicated the con- ditions. Mr. Ira A. Shaler, Assistant Engineer, found the following equations for determining the width of the base by making the proper substitutions for this special case in the general Equations (I) and (III), pages 16 and 20: ato +¢ — hr + fo)] + 2[A(69" — 1) — 2w] = 6M; 2) (2 + 20°96 — 3978) + Aa — 29°8) + Gu] = A(t — 918 + 98) — A — 9°) + Axl — 29°68 + 98) — 6wm + 4wx — gx’; in which f = the ratio of unit weight of gravel to unit weight of masonry; 9 =e g being the depth of gravel overlying the base. The other letters are used as on page 18, Having calculated the theoretical profile, it was modified in the following manner in order to obtain a practical design : ist. A few simple batters were substituted for the many changes in the theoretical form. 2d. The thickness of the profile was increased slightly between the top of the dam and elevation 170 (between which limits the water-surface is supposed to fluctuate) in order to increase the strength of this part of the wall against shocks from floating bodies, and also to add to the symmetry of the profile. Finally, a few steps were substituted for the sharp triangle of masonry between the 158 DESIGN AND CONSTRUCTION OF MASONRY DAMS. front face and the base. This change reduced the width of the base from 230 feet to 216 feet, avoiding thus a considerable amount of expensive excavation. The practical profile being designed, the pressures in the masonry were calculated, and the following results obtained : Maximum pressure at front face, . . 15.4 tons of 2000 lbs. per sq. ft. ee “ at back face,, . . 166 “ a ~ " “ oc Average “on base, . . . . 10.5 “ _ As regards the plan of the dam, the question whether it ought to be curved or straight was discussed fully in the reports of the Chief Engineer and Consulting Engineer. Both these gentlemen recommended that a straight plan should be adopted on account of the great width of the valley. In concluding our description of the proposed Quaker Bridge Dam, we wish to state that, while this structure will be about one hundred feet higher than any existing dam, the pressures at its base are within limits that the materials to be employed in the construction fully warrant, and exceed but slightly those sustained safely in the Almanza Dam for more than three centuries. The profile for the Quaker Bridge Dam has been based upon principles which the experience with many high masonry dams, built within recent years abroad, has proved to be safe, and no apprehensions need therefore be felt as regards the strength of the proposed dam to withstand successfully the thrust of the water in the reservoir and the crushing strains in its masonry. [Wote—After the above description of the proposed Quaker Bridge Dam was written, the Aqueduct Commissioners appointed Joseph P. Davis, James J. R. Croes, and Willem F Shunk, as a Board of Experts, to consider the plans proposed for this dam. The following extracts from the report of these eminent engineers give the conclusions at which they arrived as regards. the profile and plan of the dam: EXTRACTS FROM REPORT OF THE BOARD OF EXPERTS. New York, October 1, 1888. To the Honorable the Aqueduct Commissioners : By a resolution of the Aqueduct Commissioners, adopted March 7th last, and by subsequent action, the undersigned were appointed a Board of Experts to take into con- sideration the plans of the Quaker Bridge Dam, as projected by the Engineers of the Commissioners, and modifications which had been or might be suggested by others, either in plan or cross-section, and to fully advise the Commissioners on the subject. We have found that the work assigned to us required much more extended investi- gations than were anticipated, but we have at length finished them, and now have the honor to report the conclusions at which we have arrived. The proposed location of the Quaker Bridge Dam is at a point on the Croton River, at about two miles above its mouth, where the steep sides of the valley approach to form aravine. This ravine is about 1300 feet wide at an elevation of 230 feet above tide level, 300 feet wide at the level of the river-bed, 35 feet above tide, and has a rock. bottom 87 feet below the stream level, or 52 feet below the tide level in the Hudson River. It is proposed to close this ravine with a masonry dam which will impound the AMERICAN DAMS. 159 waters of the stream and raise the water level to a height of 200 feet above mean high tide. The greatest height of the dam from foundation level to the top of road parapet will be, therefore, from 265 to 270 feet, depending upon the character of the surface of the rock at the deepest point. It will be about roo feet higher than any dam yet built. It is to impound upwards of 5,000;000,000 cubic feet of water in an artificial lake 16 miles long and 165 feet deep at its lower end. The water-shed tributary to it has an area of 361 square miles and contains a number of storage basins with an aggregate capacity of 1,200,000,000 cubic feet, aver- aging about 7 miles distant from the Quaker Bridge Lake and 300 feet above its level. A new dam is now building which will increase this capacity to upwards of 1,800,000,000 cubic feet. The greatest recorded flood of the river, measured at Croton Dam, is 1,070,000,000 cubic feet in 24 hours. Most dams of great height are built of stone, laid in hydraulic mortar. This is the class of work recommended by recent writers upon the subject. The three profiles presented to us for consideration are proportioned for masonry of this kind, and we understood that its use for Quaker Bridge Dam had been determined upon by the Aque- duct Commissioners. We have therefore limited our studies to dams so built. Our first discussions related chiefly to the forces, whether usual or exceptional, that might be brought to bear upon the structure. These were classed under four general heads: (1) The quiescent and ever-acting forces, such as the weight of the masonry and the pressure produced by the impounded water. (2) Forces produced by the expansion of ice in place, or by floating masses. (3) Forces produced by waves of translation, the possible cause of such waves being the giving way of a dam above or an extensive land-slide. (4) Earthquake shocks. Quiescent Forces——It was determined that the specific gravity of the masonry should be taken at 2.34, making the weight of a cubic foot equal to 2.34 times 62.5 pounds, or 146.25 pounds. Krantz assumes a specific gravity of 2.3, or a weight of 143.75 pounds per cubic foot for masonry built of hard stone (granite or limestone). The experiments of M. Bouvier upon granite rubble led him to adopt a weight of 147.3 pounds per cubic foot. While building Boyd’s Corner Dam on the Croton River, a careful account was kept of all the materials entering into its construction, from which account the specific gravi- ties of the various classes of masonry were computed. These varied from 2.13 to 2.71, and the specific gravity of the whole mass was found to be 2.34,and we have thought it best to adopt the same specific gravity for the Quaker Bridge Dam. The aggregate length of the spillways will be about 1300 feet. A depth of about 2.25 feet on the crest would pass the largest recorded flood in the valley, and it will be only on rare occasions that the water can reach the elevation of 202 feet above the tide. This elevation for the water surface, as producing what may be termed the maxi- 160 DESIGN AND CONSTRUCTION OF MASONRY DAMS. mum quiescent stresses, has been adopted in computing the pressures which the masonry throughout the body of the dam must resist. The wasteway, or channel for carrying off the surplus waters from the surface of the reservoir, will be constructed in rock cuts and over subsidiary dams so situated that the overflowing water will not touch the main dam. fee—In our search for information upon the expansive force of ice in place, caused by increase of temperature, we found little of value recorded; but we obtained valuable, though somewhat conflicting, information by correspondence and personal interviews, which information, supplemented by experimental data, concerning its strength, elasticity, and rate of expansion under a rising thermometer, has led us to the opinion that the dam should be proportioned to resist a thrust at the highest ice line of about 43,000 pounds per lineal foot. More positive information was available regarding the force exerted by ice-floes. Under certain unfavorable conditions, where ice-jams form in a quick-running current, it appears to be almost irresistible by direct opposition. But as, in the case of the Quaker Bridge Dam, the water current, when there is one, will tend to divert the floes away from it, and direct impact can be produced only by sheets of ice driven by the wind, we have concluded that, if the dam be proportioned to resist the pressure of 43,000 pounds per lineal foot, above mentioned, it will be of ample strength to withstand the attack of floating masses. Waves of Translation—To secure the dam from injury by waves of translation, its upper portion, where the effect of such waves would be greatest, has been so designed as to give a coefficient of at least 2 against overturning, when the water level may be at an elevation of 214 feet above tide, or at the top of the parapet. Earthquakes Earthquake shocks may vary from a slight tremor to an immeasurable force. The dam, if proportioned to resist the forces before considered, will have ample stability to withstand all but shocks of the severest nature. Probably of all the consid- erable structures in the region affected by such an earthquake it would be the last to succumb. The Profile or Cross-section of the Dam.—To resist these forces, or at least those of them which may be considered measurable, we have agreed: (2) That the coefficient against overturning should, at all points, be not less than 2; (6) That the ratio of the weight of the masonry above any horizontal plane or joint, to the maximum force tending to cause sliding or shearing along the plane, should not be less than 3 to 2; (c) That the maximum quiescent stress on the down-stream end of the joints at the elevation of the river-bed, 35 feet above tide, should not exceed Io tons per square foot (139 pounds per square inch); (d) That below that elevation, where the strength of the masonry to resist crushing is aided by the lateral pressure of the earth, the maximum quiescent stress should not exceed 14 tons per square foot (194.5 pounds per square inch); and (e) That the pressures upon the joints of the up-stream face may be somewhat greater, since they will be permanently reduced as soon as the reservoir begins to fill. We agree in judging it prudent that in so important a structure as the Quaker Bridge AMERICAN DAMS. 161 Dam these conditions should be fulfilled, and we believe that, if fulfilled, the cross-section will be amply strong for the functions it will be called upon to perform. The profile designed by the Engineers of the Aqueduct Commissioners, and submitted to us by the Commissioners, does not meet the requirements which we think should be met for complete safety. We were therefore, under our instructions as we understood them, called upon to prepare a profile which we could recommend for adoption. We have prepared such a profile, and herewith present it under the title Profile N. (See Plate LXXIX ) Comparing this profile with that of the Aqueduct Engineers, which we have designated Profile Y * (see Plate LXXIX.), the chief point of difference is in the greater thickness of N in the upper portion of the dam. This increase of thickness appears necessary to resist the shock of ice and excessive freshets. The amount of masonry above the plane 100 feet below the level of the flow line of the reservoir will be about 40,000 cubic yards greater by Profile N than by Profile Y. We have given the plans laid before us, and the arguments presented to us relative thereto, attentive consideration, covering a field of study so extensive that it has seemed advisable to present herein only the conclusions upon which we are agreed, and not to spread before the Commissioners the method by which they have been reached, or a discussion of the several arguments in detail. As to curved and straight plans generally, without reference to the Quaker Bridge loca- tion, all authorities agree that the same principles should be followed in the designing of the profile, whatever the plan, unless the curve has a very short radius, not exceeding, say, 300 feet. In studying the transmission of pressures through the masonry of a dam built on a curved plan and subjected to water pressure on one side, we have made calculations of their magni- tude, which, while only roughly approximate and showing limits which probably are not ex- ceeded, rather than actual values, yet have appeared to us of sufficient weight to materially aid in reaching just conclusions. Our conclusions may be thus stated: (1) That, in designing a dam to close a deep, narrow gorge, it is safe to give a curved form in plan and to rely upon arch action for its stability; if the radius is short, the cross section of the dam may be reduced below what is termed the gravity section, meaning thereby a cross- section or profile of such proportions that it is able, by the force of gravity alone, to resist the forces tending to overturn it or to slide it on its base at any point. (2) That a gravity dam, built, in plan, on a curve of long radius, derives no appreciable aid from arch action so long as the masonry remains intact; but that, in case of a yielding of the masonry, the curved form might prove of advantage. The division between what may be called a long radius and what may be called a short radius is of course indefinite, and depends somewhat upon the height of the dam. In a general way, we would speak of a radius under 300 feet as a short one, and one of over 600 feet as a long one, for a dam of the height herein contemplated. (3) That, ina structure of the magnitude and importance of the Quaker Bridge Dam, the question of producing a pleasing architectural effect is second only to that of structural sta- bility, and that such an effect can be better obtained by a plan curved regularly on a long radius than by a plan composed of straight lines with sharp angular deflections. * This profile is shown by the dotted lines in Plate LXXIX. 162 DESIGN AND CONSTRUCTION OF MASONRY DAMS. (4) That the curved form better accommodates itself to changes of volume due to changes of temperature. While danger of the rupture of the masonry of the dam by extraordinary forces, if built on the profile herein recommended, is, in our opinion, very remote, yet it exists; and because it exists, and because the curved form is more pleasing to the eye, better satisfies the mind as to the stability of the structure, and more readily accommodates itself to changes of temperature, we think that it should be preferred in any case where it would cause no great addition to the cost. In comparing different locations of the dam, in order to discover the one which com- bined most effectively the advantages of economical construction and pleasing effect, we were confronted with the fact that our calculations indicate that, in a dam built upon a curved plan of large radius, the bottom down-stream toe pressures are increased beyond those in a straight dam of the same section, in consequence of the length of the toe being less than the length of the face to which the pressure of the water is applied. This increase of pressure is not exactly proportional to the decrease of length of toe, but is of such magnitude that it should not be neglected in designing the section of the dam; and it involves the necessity of increasing the mass of masonry in acertain proportion to the radius of the curvature. Conclisions.—In view of the premises and pursuant to our instructions, and believing that the dam will be more pleasing in appearance and better able to resist extraordinary forces if built on a curved plan, and bearing in mind that an excessive thrust in the direction of the curve cannot be produced until the force of gravity has been overcome, and that the profile N is so proportioned that more than twice the greatest pressure exerted by any conceivable ordinary force is necessary to overcome the resistance of gravity, we recommend the adoption of the Profile or Cross-section N, and of a curved plan on a radius of about 1200 feet as hereinbefore described, and we advise that the exact line be determined after further borings shall have established the most desirable location on the conditions prescribed. It should be added, in conclusion, that the form and dimensions herein recommended for adoption are prescribed on the assumption that the structure shall be well founded, and that its material and workmanship shall be of the first class in their several kinds. Respectfully submitted, Jos. P. Davis, J. J. R. CROEs, Wy. F. SHUNK.] The New Croton Dam (Plates LXXX to LXXXIV).—In the preceding pages we have given an account of the plans prepared for the proposed “Quaker Bridge Dam.” Owing to the strong opposition made to this project, the Aqueduct Commissioners decided to build a dam about 14 miles farther up-stream on property belonging to A. P. Cornell and others. From this site the dam was at first called the ‘Cornell Dam,” but this name was soon changed to the “New Croton Dam,” the reservoir wall built, 34 miles farther up- stream, in 1839-1843, to form Croton Lake, being designated as the “Old Croton Dam.” The profile adopted for the New Croton Dam was based entirely on the profile pre- pared by the engineers of the Aqueduct Commissioners for , the Quaker Bridge Dam (Plate LXXVIII), the only difference being that the sharp angles of the latter were AMERICAN DAMS. 163 rounded off by the introduction of more changes of batter in the faces and also by in- creasing the width of the profile of the former dam, somewhat near the top. Both faces of the New Croton Dam were designed to have polygonal outlines, but in actually build- ing the dam curves were substituted for polygonal outlines for the down-stream face. The construction of the New Croton Dam was begun on September 20, 1892, and was practically completed by January 1, 1907, with the exception of the ’ flash-board equipment for the overflow-weir. The cost of the dam under the original contract, including the construction of about 20 miles of new highways and the reinforcing of about 3 miles of the Old Croton Aqueduct, which is submerged in the reservoir, amounted to $7,631,185.60. According to the contract plans the dam was to consist of three parts, viz. (Plates LXXX and LXXXI): 1. A central masonry dam, about 600 feet long, extending across the valley and well into the south slope. 2. A masonry waste-weir, about 1000 feet long, to be built along the rocky side hill forming the north slope of the valley. The waste-weir was to be located nearly at right angles to the main dam and to have its ends connected to said dam and to the hillside by curves. A waste-channel, 50 feet wide at its upper end and 125 feet at ts lower end, was to be excavated in rock between the waste-weir and the hillside. 3. An earth dam with masonry core-wall, about 600 feet long, forming a continua- tion of the masonry dam to the south side of the valley, which was to be built according to the cross-section given on Plate XCIV, Fig. 1. The masonry dam, waste-weir, and core-wall were all to be founded on rock and to form a continuous wall of masonry across the valley. At the junction of the earth and masonry dams a large masonry wing-wall was to be built. The top of the dam was to be finished as a roadway, which was to be carried across the waste-channel on an arched bridge of 200 feet span. The manner in which the earthen dam was to be built is described on page 242. On Septemker 16, 1896, the Aqueduct Commissioners decided to extend the masonry dam rio feet to the south and to reduce the length of the earth dam by the same distance. This change reduced the maximum height of the earth dam from 120 to 50 feet. The discovery of some cracks in the core-wall of the earth dam, which was to have a maximum height of 200 feet, gave rise to some doubts about the safety of this part of the dam. On June 21, 1901, the Aqueduct Commissioners appointed a board of engineers (J. J. R. Croes, Edwin F. Smith, and Elnathan Sweet, members of the American Society of Civil Engineers) to examine the plans for the construction of the dam and the work of con- struction as far as the same had proceeded, and to report to the Aqueduct Commissioners what changes, if any, should be made in the plans for the construction of the dam. On November 18, 1901, the board of engineers handed in its report, in which it recommended that practically the whole earth dam should be replaced by a masonry dam similar to the one already built, in order to make the dam absolutely secure against disaster. This recom- mendation was adopted by the Aqueduct Commissioners on April 16, 1902, and the earth dam, which had been about half constructed, was- replaced by a masonry structure, with the exception of a short piece 128 feet long from a gate-house built at the point where 164 DESIGN AND CONSTRUCTION OF MASONRY DAMS. the Old Croton Aqueduct crosses the dam, to the southerly end of the dam. The maximum height of this earth bank is only 26 feet. According to the contract plans the different parts of the dam were to be finished at the following elevations, which refer to Croton Datum, i.e., mean tide at the mouth of the Croton River: Top of waste-weir, elevation 196; top of masonry dam, eleva‘ion 210, and top of earth dam, elevation 220. On October 16, 1900, the Aqueduct Commissioners decided to finish the whole dam at elevation 216, and the waste-weir at clevation 200, with the exception of a depressed part 250 fect long, at the junction with the masonry dam, which was to have its crest at elevation 106. Protective Works.—Owing to the great depth to which the foundation-trench for the masonry dam had to be excavated, expensive works were required for turning the river from its former course. A new channel for the river, 125 feet wide and about 1100 feet long, was excavated in the rock on the north side of the valley. To avoid expense it was kept 5 feet higher than the old bed. The river was confined in its new channel on the north by the slope of the hill, and on the south by a masonry wall continued at both ends by earthen dams which extended across the old channel, the upper one serving to turn the river into its new course. The wall was built for about 300 feet on each side of the centre-line of the dam; it was 3 feet wide.at the top and 13 feet at the base, its height being 23 to 25 feet above the grade of the new channel. The face towards the water-channel was almost vertical. On the other side of the wall (except where it crossed the site of the dam) an earth embankment was carried up for about half its height. Some portions of the wall which form permanent work were made stronger than the dimensions given. The masonry wall was continued at each end by an earthen dam, ro feet wide on top and about 30 feet high. Towards the channel the banks were sioped 14 to 1, and on the opposite side 2 to 1. Water-tightness was insured in these earthen dams by providing them with a core- wall formed of two courses of 3-inch tongued-and-grooved sheet-piles, which extended 3 feet below the tcp of the banks to about 20 feet below the original surface. The two courses of sheet- piles were spiked tcgether and were stiffened above the river-bed by frequent courses of horizontal range timbers, which were fastened to the sheeting as it was put in place. The toe of the slopes on the channel side was formed of heavy cribwork 10 to 12 feet high. In both dams two cribs, each 1o feet wide, were placed 6 feet apart, the space between them being filled with compact earth. The cribs were joined tcgether by frequent cross-ties extending through the 6-foot spaces. The outer faces of the cribs and those on each side of the filling just mentioned were covered with 3-inch tongued-and-grooved sheeting, sunk 34 to 1o feet into the ground below the bottom of the crib. The cribs were to protect the toe of the embankments against the scouring action of the water, which had a depth of 15 to 19 feet during great freshets. The total length of the masonry and earth dams which bound the new channel of the river on the sound was about 1600 feet. Excavation for Foundation.—Owing to the great width of the base of the dam (maxi- mum, 206 feet), the excavation for the foundation had to be made in open trench. In the centre of the valley, sand, gravel, and boulders had to be excavated to a depth of about 7o to 75 feet before the bed-rock was uncovered. Towards the south side of the valley the rock was found to be covered by a layer of hardpan, about 120 feet deep, upon which there was a layer of sand and gravel. PLATE N. NEW CROTON DAM. . PLATE O. NEW CROTON DAM. EXCAVATING FOR FOUNDATION. NEW CROTON DAM. LAYING MASONRY IN FOUNDATION TRENCH. AMERICAN DAMS. 169 The excavation below the river-bed was made at first with a large dredge having a 24-cubic-yard dipper on an 80-foot boom. This dredge, which excavated about 800 cubic yards in 1o hours, had to be kept floating in the foundation-trench and was replaced by a steam-shovel of the same capacity when the bed-rock was reached. At one time three steam-shovels were used in making the excavation for the foundation. Three Lidgerwood cableways, each about 1200 to 1600 feet long, were stretched across the foundation-trench 50 feet apart. They were used in making part of the excavation and, later, in delivering some of the materials required for the masonry. The material excavated was shoveled into skips, holding about 3 cubic yards, which were hoisted and transported by means of the three cableways. As the excavation assumed larger proportions, the cableways were supplemented by railway inclines, placed at different points on the side slopes and operated by means of stationary hoisting engines and cables. From the inclines the mate- rials excavated were hauled by locomotives on a 36-inch-gage track to the spoil-banks. The bed-rock was found to be gneiss on the north side of the valley and limestone in the centre and on the south side. The two kinds of rock join each other on a line about parallel with and directly under the old river-bed. At the junction of the gneiss and limec- stone a layer of black schist occurs, about 4 feet wide in places, which extends for a short distance below the surface of the rock. Below the schist the gneiss and limestone are j>ined like one rock. The gneiss rises rapidly with the north hillside, cropping out in places. The limestone extends level across the valley for a distance of about 4oo feet and then rises gradually with the slope of the hillside, being about 25 feet below the surface at the south end of the dam. The rock upon which the dam had to be founded varied much in character. The gneiss was much fissured and full of seams. The limestone was found, in some places, to be sufficiently hard and water-tight to answer for the foundation, while in other places it was so soft that it could be excavated with a pick and shovel. There were many seams in the limestone and, in one case, a cave, whose dimensions were about 12 X14 X2o feet, was discovered under a heavy stratum of solid rock. All the seams in the limestone contained more or less water, which was, in some cases, under heavy pressure. In one instance the water was under a head of go feet, requiring a ro-inch pipe to carry it off. A great many test-holes were drilled to explore the seams and the rock was excavated to a sufficient depth to insure a good foundation. The maximum depth to which the rock had to be excavated was about 54 feet; the average depth was about 20 feet. The greatest depth of the foundation was 123 feet below the river-bed. In excavating the foundations for the core-wall, which according to the original plans was to extend about 600 feet from the masonry dam to the side hill, 8 to 24 feet of sand was removed by steam-shovels before the hardpan that overlaid the rock was reached. The excavation through the hardpan and 4 to 7 feet into the rock was made in ‘‘vertical trench,”’ which was made 6 feet wider than the foundation of the core-wall to allow sufficient space for laying the masonry and for backfilling. The sides of the trench stood vertical when excavated and were sheeted and braced afterwards, as required. The total amount of material excavated for the foundations of the dam was about 1,821,400 cubic yards of earth and 400,250 cubic yards of rock. 179 DESIGN AND CONSTRUCTION OF MASONRY DAMS. Masonry.—After solid rock had been reached and all loose and shaky pieces had been removed, the bottom was thoroughly washed by streams of water under heavy pressure and cleaned with brooms. The rock was then “painted” with a grout of neat cement, applied with brushes, which filled up all small cracks or seams. All erosions and open seams were filled with grout, usually made of Portland cement and fine, sharp sand, mixed, either 1 to x or r to 2, according to whether the grout had to be pumped or poured. Large seams were filled by placing small stones in the grout. Spriags that were encoun- tered in the foundation were either drained off to a sump-hole or were confined in verticas pipes which were finally filled with grout or, in a few cases, with clay that was forced by a drop-hammer into the pipes. The laying of the foundation masonry was begun on May 26, 1896. With the excep- tion of the extension of the main dam (ordered on April 16, 1902, to replace the earth dam), which was built of cyclopean masonry, the dam and the waste-weir were constructed of rubble masonry, faced above the backfilling with ashlar masonry classified as “ facing stone masonry.” In the bottom foundation courses Portland-cement mortar, mixed 1:2, was used. Above the foundation the masonry was laid in American cement mortar, mixed I to 2, except in winter, when Portand-cement mortar, mixed 1:3, was used. The ashlar ‘“‘facing stone masonry” begins at the waste-weir at the rock surface and for the main dam above the refilling, which was brought up to elevation 70 (i.e., about 27 feet above the old river-bed). This masonry has a depth of at least 28 inches, and is laid in courses ranging in rise from 30 to 20 inches. The joints do not exceed 4 inch for 4 inches from the face and not over 2 inches wide for the remaining depth. The stretchers are 3 to 7 feet long, and in each course every third stone is a header, at least 4 feet deep. All joints in the up-stream face of the dam and waste-weir were raked out to a depth of 2 inches and pointed with Portland-cement mortar, mixed 1 to 1. The stone used for the greater part of the dam is a dark-colored granite, named “ gabro” tock Ly geologists. It weighs about 185 pounds per cubic foot, and is very hard and tough. The work of laying the masonry was continued in winter except in extremely cold weather, when the thermometer remained steadily below the freezing-point. In laying masonry in cold weather salt was added to the cement, the sand was heated in large boxes, provided with steam-coils, and warm water was used in mixing the mortar. On cold nights the fresh work was covered with canvas and in the morning the surfaces and joints of the work were thoroughly cleaned with steam and hot brine. The maximum force employed on the work, including the quarry, was 851 men (475 on the dam and 376 in the quarry). The best month’s work in the foundation was in June, 1898, when 17,186 cubic yards of masonry was laid. The description given above applies to the masonry laid in the dam and waste-weir accord- ing to the original plans. The extension of the dam, which was ordered to be made to replace the earthen dam, was built of cyclopean masonry, faced above the backfilling with “facing stone masonry” like the rest of the dam. The profile of the extension of the main dam was made slightly thicker than the contract drawing required, viz., 2.1 feet thicker at elevation 150, the increase diminishing to o at elevations 100 and 180, respectively. This was done because the then Chief Engineer, J. Waldo Smith, M. Am. Soc. C. E., considered the profile of the dam to be somewhat deficient in strength in the upper part. PLATE P. NEW CROTON DAM. TEMPORARY CHANNEL. NEW CROTON DAM. LAYING MASONRY ACROSS TEMPORARY CHANNEL. PLATE Q. NEW CROTON DAM. RELIEF OPENINGS IN DAM. NEW CROTON DAM. UP-STREAM FACE. AMERICAN DAMS. 175 The cyclopean masonry consists of large quarry stones, bedded in concrete mixed rather wet in the proportion of 1:2:4, the spaces between the large stones being, also, filled with concrete. About half the bulk of this masonry is concrete. The cyclopean masonry was laid much more rapidly than the rubble masonry that was used for the main part of the dam and for the waste-weir. One Ransome concrete-mixer and three 4-foot cubical mixers were used on the extension of the dam. Part of the time the work was continued day and night. The maximum amount of cyclopean masonry laid per month was about 16,000 cubic yards, in August, 1904. In order to avoid the delay caused by shifting derricks, two platforms were erected within the limits of the masonry on the axis of the dam (Plate R*). The platforms were 55 feet apart. Each platform was supported by six steel columns, about so feet high, which were securely anchored to the masonry and braced. The tops of the columns were joined by I-beams, which were covered with 3-inch planks so as to form a platform 25X50 feet, the longer dimen- sion being parallel with the axis of the dam. Four derricks were placed on each platform and kept in use until the masonry reached the level of the platform, viz., elevation 130 (i.e., 86 feet below the tcp of the dam). As the masonry was carried up the braces and finally the woodwork of the platforms were removed, but the columns were left in the masonry. After the masonry had reached the top of the platforms, a trestlework was built against the down- stream face to support a platform for the derricks and the building materials. Additional trestle-bents were added as the work was carried up (Plate S). The Waste-weir—The steps on the down-stream side of the waste-weir were built of ‘‘block stone masonry,” having a uniform rise of 2 feet and sufficient depth to bond under the next step above. The upper two steps of the waste-weir were coped with large blocks of granite dimen- sion stone, having the exposed surfaces rough pointed. Each of these coping stones was securely anchored to the masonry by means of two 13-inch twisted Ransome bars, 34 feet long, which were placed in 2-inch holes, drilled in the coping and masonry and leaded. Buttresses, etc.—The down-stream face of the dam is relieved by four buttresses (see Frontispiece and Plate N). The two central buttresses project about 15 feet, while the. two buttresses near the ends of the dam project only 4 feet. On the up-stream side two pilasters are built by corbeling out, opposite the two central buttresses of the down- stream face. They project 14 feet. A stairway leading to the floor and roof of the vault-chamber of the blow-off pipes is constructed on the down-stream side of the dam, near its north end. From the level of the roof of the vault-chamber, the stairway is continued inside of the adjoining buttress to the top of the dam. A s‘milar stairway leading to a platform at elevation 158 is constructed at the next buttress to the south, at the place where originally the earth dam joined the masonry dam, in order to cover the lower part of the dam at this point, which had not been provided with a cut stone facing, as it was to be covered by the slope of the earthen dam. * The photographs of the New Croton Dam which are reproduced in this book were taken by Pierre Pullis, 32 Park Place New York. 176 DESIGN AND CONSTRUCTION OF MASONRY DAMS. The ornamental masonry used for the cornice, the parapets at the buttresses, arches for stairway, etc., are built of granite dimension stone. Two Gate-houses were constructed, in connection with the dam, for controlling the flow from the reservoir. The first, known as Gate-house No. 1 (Fig. 36), is built on the down-stream face of the dam near its south end. It regulates the flow into the Old Croton Aqueduct, which crosses the dam at this place. The substructure of the gate-house, which is 55} feet high, contains four water-chambers. The Old Croton Aqueduct, the flow into which is controlled at the New Croton Gate-house, constructed about three miles above the New Croton Dam, is connected by a brick conduit, 360 feet long, with the southeast chamber. The water flows from this chamber through two sluiceways, each controlled at each end by a 2}X6-foot sluice-gate, into the southwest chamber, which is connected by a masonry conduit, 510 feet long, with the Old Croton Aqueduct below the dam. Water can be drawn at the dam into the northeast chamber of Gate-house No. 1 through a bottom, a middle, or a surface inlet, as may be desired. These inlets consist of masonry conduits Fic. 35.—Maximum SECTION. Fic. 36.—GATE-HOUSE No. 1. respectively 510 feet, 410 feet, and 22 feet long, having an oval cross-section, 6 feet wide by 1o feet high, on the inside, with an area equal to that of acircle 7} feet in diameter. The inlets can be closed at the gate-house by timber drop-gates, for which iron grooves are provided in the inlet-openings at the gate-house. The northeast chamber is connected by two sluiceways, each controlled at each end by a 24X6-foot sluice-gate, with the south- east chamber. It is also connected by an oval passage, 10 feet high by 6 feet wide, with the northwest chamber, from which the water can pass through two sluiceways, each con- trolled at each end by a 2$X6-foot sluice-gate, into the southwest chamber. The oval passage between the northeast and the northwest chambers can be closed by timber drop- gates. An outlet, controlled by two 2X8-foot sluice-gates is constructed at the northwest corer of the gate-house, which can be connected in the future with a screen-chamber and, then, either with the Old Croton Aqueduct or some new conduit for New York. Iron AMERICAN DAMS. 177 pipes, 12 inches in diameter, are placed beneath the floor of the substructure for draining the different water-chambers whenever it may be necessary for repairs or inspection. The different sluice-gates of the gate-house are operated in a vault, constructed beneath the level of the roadway on top of the dam. Gate-house No. 2 (Fig. 37) was constructed on the up-stream face of the dam at the junction of the masonry dam with the overflow-weir to control the flow through three 48-inch blow-off pipes, which are laid in the masonry of the dam at about elevation 92. The flow into each of these pipes is regulated in the following manner. An_ inlet-opening 4 feet wide and 524 feet high is constructed in the up-stream face of the gate-house. Its width is reduced in 2} feet to 3 feet. The inlet connects with a chamber 3 feet wide by 64 feet long extending to the floor of the gate- <4" Diem, house (elevation 207). Two sets of 66-inch grooves FL suncoe are cut in the sides of this chamber, the up-stream set being used for iron screens, while the down-stream "Sq. . ew am jushing, Comp Metal set serves to guide a wooden drop-gate which controls the flow of water from the chamber just described Fa = s : Jor’ itl \ Qs : : : : ep aX . into a sluiceway, 3 feet wide, 6 feet high, and 8 feet Ce i OS z ‘ I = long, which leads to a second chamber extending to the sf, to oathk | 3 ‘ as t | 234 Square 7 floor of the gate-house. For 4 feet this chamber has gapt | | 3 2 . 36 1 A-dth => tf B a width of 7 feet, and for 2 fect, at its down-stream P) ppd t Composition fiji}\y¥ Cast Iron TRL Vales Gate Ilouse = = BT Tesco, pa eal yy! ied £ vA 7 vot | iil (Port ¥ BHQ Ai Jir ey hes Wei = Dos eges=- 27 7ST TTT TT _ composition Mota” PLSTY pseaesceda! 48” Diam----------: Bridge = == AE sl v tit a f Lu HU Ratan PART HORIZONTAL SECTION Blow-olf || e PART SECTIONAL PLAN Fic. 37 —GaTE-HOUSE No. 2. Fic. 38.—BALANCED VALVE. end, the width is reduced to 3 feet. Grooves are provided in the sides of this chamber, at its down-stream end, for a sluice-gate 3 feet wide by 6 feet high, which is operated from the floor of the gate-house, and controls the flow into a second sluiceway, 3 feet wide, 6 feet high, and 8 feet long. The sluiceway last described leads to a circular well 12 feet in diameter, constructed in the masonry of the gate-house with its bottom at elevation 99.25. The masonry lining of the well is corbeled, beginning at the elevation 196, so as to terminate the well at the floor of the gate-house with a rectangular opening 7$X12 feet in section. At the 178 DESIGN AND CONSTRUCTION OF MASONRY DAMS. bottom of the well a 48-inch elbow is embedded in the masonry and is connected with one of the blow-off pipes. The inlet into the elbow is controlled by a cylindrical, balanced valve having a conical seat (Fig. 38). This valve is placed in a tight cast-iron casing, which has eight ports through which water can flow into the blow-off pipe when the valve is raised, which is done by means of a stem extending through the casing to the floor of the gate- house, where the hoisting machinery is placed. Each blow-off pipe has, also, a stop-cock which is placed in a vault on the down-stream side of the dam. A 12-inch by-pass pipe, provided with a stop-cock, is placed at the stop-cock of the blow-off pipe in order to reduce the pressure when this stop-cock is to be opened. On each side of the 48-inch stop-cock a 6-inch blow-off is placed at the bottom of the 48-inch pipe. ‘A 12-inch iron drain-pipe is laid from each of the circular wells in the masonry of the dam to the stop-cock vault, where it is connected with one of the blow-off pipes. This pipe begins at the bottom of the well with an elbow provided with a balanced valve, similar to that of the blow-off valve. From the south drain-pipe a 12-inch iron pipe is laid to a fountain, where it is connected to five vertical jet pipes, one of 6 inches and four of 4 inches diameter. The basin of the fountain has a diameter of 50 feet, and is connected by a 20-inch overflow- and discharge-pipe with the Croton River. While the foundation of the dam was being constructed below the river-bed, the Croton River was confined in a new channel, 125 feet wide, constructed along the north hillside, as already described. When the masonry was carried up above the river-bed an arched relief opening was constructed in the masonry to permit the river to flow through the dam. The arched opening (Plate Q) was constructed at the new river-channel at about elevation 50. It was made 28 feet wide by 24 feet high at the up-stream face and 20 feet wide by 21 feet high at the down-stream face. The reduction in width and height of the opening was made by four offsets and the sides were “toothed” so as to bond with the concrete with which the opening was finally filled. After the opening had been filled with concrete, grout was forced through small pipes, imbedded in the masonry near the top of the opening, to fill any void spaces that might be found in the concrete. Two 48-inch scour-pipes were imbedded in the concrete at the bottom of the relief opening. The flow into each of these pipes is controlled on the up-stream face of the dam by a 2X 5-foot sluice-gate, which is operated by hoisting machinery placed on a small platform constructed at elevation 153, which can be reached from the top of the dam by means of a ladder. Ordinarily this platform is submerged and the scour-gates can only be opened when the water surface of the reservoir has been lowered by means of the three blow-off pipes to elevation 150. Each of the scour-pipes is provided at the down-stream face of the dam with a stop-cock having a 4-inch by-pass pipe with a stop- cock to relieve the pressure. A’ vault is built over these stop-cocks. In order to provide an ample outlet for the Croton River during floods, and, also, to facilitate the transportation of building materials from one side to the other of the dam, a second arched opening was constructed in the dam at elevation 60, just south of Gate- -house No. 2. This opening was 22 feet wide Ly 23 feet high at the up-stream face of ‘the dam and 18 feet. wide by 21 feet high at the down-stream face, the reduction in width -and height being made by two offsets. The sides were toothed and the opening was finally closed with concrete, as in the case of the arched opening at the river-channel. PLATE. RB. re Ce 4 MC 6G ME od ee, Tle. Fl nal NEW CROTON DAM. TRESTLE ON DOWN-STREAM FACE, ‘SHVG AYNOSVN JO NOISNALXH ONIGTING ‘NYG NOLOWO MAN PLATE S. Sb keiiy NAGY r EN RNY AMERICAN DAMS. 183 No pipes were laid in the masonry, except the small pipes used for grouting the con- crete. On January 22, 1905, the scour and blow-off pipes of the dam were closed for the first time, and the reservoir was allowed to fill. By April 1, 1905, the water had risen in the reservoir to about elevation 170. It was not allowed to rise more than a foot or two above this level, as some refilling, etc., remained to be done, and in the following October the water was drawn down to elevation 55 to permit the contractors to complete their work. The last stone was laid in the dam on January 17, 1906. A roadway 19} feet wide, formed of concrete laid in sections 6 feet wide, was constructed on top of the dam. The front face of the dam was corbeled out near the top, in order to get the width required for the roadway. The drainage from this roadway is discharged by 8-inch vitrified pipes (placed at intervals of 114 feet on both sides of the roadway and provided with suitable gratings in the gutters) into a 4%4-foot sewer constructed in the masonry of the dam under the roadway. Iron railings are placed on both sides of the roadway, except at the buttresses and pilasters, where stone parapets are built. The railing consists of wrought-iron pipes with cast-iron post caps, bases, and special channels. The railing has panels 9} feet long between the centres of posts and is 4 feet high above the masonry base. Each post is anchored by 4-inch bronze bolts to the masonry, the bolt-holes being grouted with Portland cement. All ironwork was galvanized and given three coats of paint after being erected. The roadway is carried across the waste channel by a steel arch bridge of 200 feet span. Contractors’ Plant.— The contract for the New Croton Dam included, in addition to the work of the dam, the construction of 21 miles of new highways and the repairs and reinforcement of 3 miles of the Old Croton Aqueduct that were to be submerged by the reservoir. The principal items of the plant used by the contractors on this work were: 11 locomotives for 36-inch gauge. 82 flat cars for 36-inch gauge. 200 dump-cars for 36-inch gauge. 750 tons of steel rail (30-40 pounds per yard). 3 steam-shovels (bucket 14-24 cubic yards). 1 dredge, 80 feet boom, 3 cubic yards bucket. 39 steam-boilers, total capacity 1,400 H.P. 15 steam-pumps, total capacity 20,000,000 gallons per day. 51 hoisting-engines. 11 steam-engines, 10-50 H.P. 20 steam-drills. 75 derricks (boom, guy, and stiff-leg). 3 cableways, 1,250 to 1,650 feet long, with engines, etc. 3 stone-crushing plants. 8 concrete-mixing machines, etc., etc. The pumping-plant required for the foundation-trench consisted of three Worthington compound pumps, each having a nominal capacity of 4,000,000 gallons in twenty-four hours against a head of go feet. i&4 DEISGN AND CONSTRUCTION OF MASONRY DAMS. Force Employed, etc—When the construction was at its height the contractors empl.yed a force of about 1,564 men. In performing the work covered by their contract, including highways, etc., the contractors used about 381,000 barrels of American cement, 365,000 barrels of Portland cement, and 125,000 tons of coal. All of this material had to be hauled by teams from Croton-on-Hudson to the dam, a distance of about 24 miles, as the contractors were prevented from building a railroad from the New York Central and Tludson River Railroad to their work on account of charters that had been obtained by private parties, who wished to sell these charters to the contractors at exorbitant prices. Engineers.—The plans for the New Croton Dam were prepared by the late A. Fteley, Past President Am. Soc. C. E., Chief Engineer of the Aqueduct Commission. The construction of the work was carried on under the direction of Mr. Fteley from September 1, 1892, to January 1, 1900, when he resigned on account of ill health, W. R. Hill, M. Am. Soc. C. E., succeeded Mr. Fteley as Chief Engineer and directed the work of con- struction until he resigned on October 14, 1903. J. Waldo Smith, M. Am. Soc. C. E., was appointed on October 15, 1903, Chief Engineer of the Aqueduct Commission and served in that capacity until August 1, 1905, when he resigned. Walter H. Sears, M. Am. Soc. C. E., was placed in charge of the work as Acting Chief Engineer, and on January 9, 1906, the Aqueduct Commissioners appointed him Chief Engineer. Charles S. Gowen, M. Am. Soc. C. E.,* was in immediate charge of the work as Division Engineer from the beginning of the construction until August 31, 1905, when he resigned. On October 15, 1905, Mr. Frederick B. Rogers was appointed as Mr. Gowen’s successor. The following Assistant Engineers were in immediate charge of the construction of the dam unde- the direction of the Division Engineer: B. R. Value, September 1, 1892, to June 1, 1900; F. B. Rogers, June 1, 1900, to October 15, 1905; C. E. Smith, October 15, 1905, to completion. Contractors.—The contract for constructing the New Croton Dam was awarded on August 26, 1892, to James S. Coleman, the lowest bidder, at his bid of $4,150,573. Mr. Coleman assigned the contract for the construction of the dam on January 2, 1895, to the firm of Coleman, Ryan & Brown, who on July 13, 1899, assigned the contract to Coleman, Breuchaud & Coleman. The original contractor, James 5. Coleman, was the senior member of both of the firms mentioned above. The Indian River Dam, New York,} was constructed in 1898, on a tributary of the Hudson, to increase the size of Indian Lake in order to store an additional quantity of water to supply the Lake Champlain Canal, to add to the water-power, and to improve the navigation of the Hudson River. The central part of the dam, which is constructed of masonry, is 207 feet long. It is 7 feet wide at the top and 33 feet wide at the base, its extreme height being 47 feet. The masonry dam is continued by an earth embankment, 200 feet long, having a masonry *Mr. Gowen has described the construction of the foundations of the dam very fully in a paper read before the American Society of Civil Engineers (see Vol. XLIII., p. 469), and has discussed the importan changes made in the plans by substituting a masonry dam for the proposed earthen dam in a second paper read before that Society on January 18, 1906. + Engineering News, May 18, 1899. AMERICAN DAMS. 185 core- wall. This embankment is 15 feet wide on top and has an inner slope of 24:1 paved with 12 inches of _stone riprap, and an outer slope of 2:1. The core-wall, which Is carried up to within 2 feet of the top of the embankment, is 2 feet thick at the top and 4 feet thick at the base. ‘On the other side of the masonry dam, a masonry waste-weir, 106.5 feet rons is constructed. It is crossed by a foot- bridge resting on five masonry piers. A logwa 18 feet wide, is constructed in the masonry with its crest 17 feet below the top of the By This opening can be closed with 45 wooien needle beams (4 X8’’Xi, AT abel 2 eR Sosa JUNIATA DAM. SHOWING WHEEL-PIT, SECTION OF GRAVEL FOUNDATION, CUT. OFF WALLS, AND PORTION OF FLOOR. JUNIATA DAM. FLOOR NEARLY COMPLETED. REINFORCED CONCRETE DAMS. 219 The Dam at Schuylerville, New York,* was constructed in 1904, for the American Wood Board Company, on the Batten Kil River. The dam was built of reinforced concrete and was made hollow, but the abutments, wing-walls, and bulkheads were built of solid concrete. The dam has a length of rollway of 250 feet between abutments an average height of 25 feet above the river-bed, and a maximum height of 28 feet. The strains in the dam were calculated for an assumed flood of 5 feet on the rollway. Fig. 49 shows the cross-section of the dam. The dam is founded on Hudson River shale. A trench, 5 feet wide and 3 feet deep, was excavated for the cut-off wall at the upper heel of the dam. No excavation was made for the buttresses or toe, the rock being only washed by a jet of water under pressure to prepare it as a foundation. The passageway in the interior of the dam forms the only means of communication between the mill on a) ee i ; lhe ill 2rt2eed ti i Sey hie oN Sih Te * Tie Rods ' Ih t I \ 2 fe. gd ih : ai it Fic. 49.—SCHUYLERVILLE Dam. the north bank and the railroad station on the south bank of the river, and is in daily use. It is dry and well ventilated by the air coming through the vents in the apron. The hydraulic works of the American Wood Board Company were designed by Mr. George F. Hardy of New York; Tucker and Vinton of New York were the general con- tractors for the dam. The plans for the dam were prepared by the Ambursen Hydraulic Construction Company of Boston, which took a sub-contract for the elaborate false-work and moulds for the dam. The construction was begun on September 27, 1904, and was completed by the following December 3rst. The Juniata Damft (Plates V and W) was constructed in 1906 on the Juniata River, at a gap in Warriors Ridge Range, about four miles west of Huntingdon, Pennsylvania. The drainage area supplying the river above this gap contains about goo square miles. The dam extends across the river in a nearly north and south direction. Its south end abuts against the foot of Warriors Ridge and the north end against the power-house. The dam has a rollway 375 feet long, having a maximum height of 27} feet. The buttresses of the dam are 10 feet, centre to centre. They are 18 inches thick at the bottom and 14 inches thick at the top, the reduction being made by a 2-inch offset at each side. Two rectangular openings are provided in each buttress. A plank walk carried through * Engineering Record, March 4, 1905. ft Ibid., December 22, 1906. 220 DESIGN AND CONSTRUCTION OF MASONRY DAMS. the upper openings serves as a passageway for inspection of the inner surface of the dam, but the lower openings were only made for convenience during the construction. The river-bed at the site of the dam consists of clayey gravel, underlain by a soft black slaty material. A cut-off wall, both at the up-stream and down-stream toe of the dam, extends down to this slate, but the floor rests on the natural bed of gravel and is provided with weep-holes to relieve any upward hydraulic pressure. as 6. Go ek ee we a ew RO Outer ‘‘ Sn ee Ge aS SP Bo os a See aes O. In building the dam the vegetable top soil was excavated to a depth of a foot from the surface that was to be covered by the embankment, except where sand was found, in which case the excavation was continued until an impervious stratum was reached. For the puddle-core that was to be placed in the centre of the dam the excavation was continued to rock, into which a groove, 5 feet wide, was cut, extending for the whole length of the dam. In this groove a wall of rubble masonry, laid in hydraulic-cement mortar, was built, “the sides being plastered with mortar. It was made 4 feet wide at the base and 2 feet wide at the top. A puddle core-wall, 36 feet wide at the base and 17 feet wide at the top, was constructed on and around the stone wall. The embankment was carefully constructed in layers. After the up-stream slope had been built of earth it was covered with 2 feet of good puddle upon which 1 foot of gravel was placed, all being carefully rolled. After the completion of the embankment the inside slope was covered with riprap of large stones from 10 feet below to 2 feet above its high-water mark. The top 6 feet of the riprap was covered with stones, r to 3 inches in diameter. The top of the dam, the outer slope, and the inner slope above the riprap were sodded. Some time after the dam had been completed, a driveway was constructed on the outer slope about half-way up. This driveway was supported by increasing the width of the dam at the outer slope. The inlet-, outlet-, and drain-pipes were originally constructed through the dam at its east end. These pipes were laid in trenches upon solid earth and were supported by stone piers, 6 feet apart, where they crossed the puddle-core. The piers were carried up and * Engineering News, February 20, 1902. EARTHEN DAMS. 237 around the pipes so as to form collars to prevent water percolating through the dam along the pipes. Some of the pipes in the earth trenches were cracked, probably because the pipes at the puddle core-wall were laid on piers, while the others were only supported by earth, thus making it impossible for the pipes to settle uniformly. The cracked pipes were removed, the ends of the remaining good pipes were closed by caps, and new inlet-, outlet-, and drain-pipes were laid on the south side of the reservoir at a point where the height of the embankment was much lower than at the main dam. The dam was designed by Robert K. Martin, Chief Engineer of the Baltimore Water- works, and was built under his supervision. The work was begun on March 7, 1864, and was completed by January 2, 1871, when the reservoir was permanently filled. The dam has proved to be perfectly water-tight. The Temescal Dam,* Califorina, was constructed in 1866-68 to form a reservoir for the water-supply of Oakland. The reservoir is located about 4} miles from the city. The work was begun by Mr. Anthony Chabot of Oakland and was completed by the Contra Costa Water Company. The dam was constructed in layers by means of carts and scrapers and was completed in 1868 with a top-width of 18 feet, at a maximum height of 105 feet above the bed of the creek, across which the dam was built. The slopes were originally 3:1 on the up-stream side and 24:1 on the down-stream side. The following year Mr. Chabot, who was a practical hydraulic miner, flattened the down-stream slope by sluicing in material by the same process that is used in hydraulic mining, and in 1886 the crest of the dam was raised 10 feet by the hydraulic method. As finished the dam has a maximum height of 115 feet above the creek-bed and a down-stream slope of 5:1. The reservoir formed by the dam covers 18 acres and has a storage capacity of 250,000,000 gallons. The San Leandro Dam }+ (Fig. 53) was constructed in 1874-76 to form a reservoir for the Oakland Water-works. The dam was finished in the latter part of 1875 with a maximum height of 115 feet above the bed of the creek across which it was built. The reservoir formed by the dam covered about 400 acres and stored about 5,000,000,000 gallons. In 1898 the crest of the dam was raised 10 feet, giving the dam a height of 125 feet above the bed of the creek and the up-stream slope was reinforced at the same time. With the water-line 5 feet below its crest, the dam forms now a reservoir covering 436 acres and having an available storage of 5,826,000,000 gallons. By silting up this capacity has been reduced up to January 1, 1903, to about 5,167,000,000 gallons. The drainage area supplying the reservoir contains about 43 square miles. Fig. 53 shows the cross-section adopted for this dam. According to the original plans the dam was to be raised ro feet every 4 or 5 years until an extreme height of 175 feet above the creek-bed should be attained. This was to be done not only to increase the storage, but also to offset the silting up of the reservoir, which averages about a foot in * Engineering News, September 11, 1902, and ‘‘Reservoirs for Irrigation, Water-power, and Domestic Water-supply,”” by James D. Schuyler, M. Am. Soc. C. E. + Engineering News, September 11, 1902; “Earth Dams,’’ by Burr Bassell, M. Am. Soc. C. E.; and ‘‘ Reser- voirs for Irrigation, Water-power and Domestic Water-supply,”’ by James D. Schuyler, M. Am. Soc. C. E. 238 DESIGN AND CONSTRUCTION OF DAMS. depth per annum. With a view to this raisirg, the dam was given a much greater width of base than would otherwise have been adopted. Within a slope of 3:1 on the up-stream side and 23:1 on the down-stream side the dam was made of selected material, placed in layers ebout a foot thick in the usual way. The material was dumped on the dam from carts and wagons and was sprinkled suf"- ciently to pack it well. No rollers were used, the earth being compacted by the carting and by a band of horses, which was led by a boy on horseback over the entire work. A central trench was excavated 30 feet below the original creek-bed and in the bottom of this trench three secondary trenches were excavated, 3 feet wide by 3 feet deep, and were filled with concrete walls, which were carried up 2 feet above the general floor of the trench in order to break the continuity of its surface. Outside of the 24:1 slope on the down-stream side the dam was constructed of ordinary earth and more or less rock that were sluiced in by gravity during the winter months. This process was carried on until the canyon below the dam was filled, giving an average slope of 6.7:1 on the down-stream side. Some material was also sluiced in in the up-stream face of the dam. James D. Schuyler states in his “Reservoirs for Irrigation, etc.,” that the dam as completed to a height of 115 feet in 1875 contained about 542,700 cubic yards of material, of which H.W:Surface | ~--~---= i Surface of silt? s —— , 7, 7 = ‘ SN - Concrete Walls, 3’x 5’ Fic. 53.—DEVELOPED SECTION OF SAN LEANDRO Dam. about 160,000 cubic yards were sluiced in. The water used for the “hydraulic method” was brought four miles in a ditch and the material was sluiced in a flume, lined with sheet-iron plates, which was built on a grade of 4-6 per cent. About 10-15 cubic feet of water per second was used for this process. It was estimated that the hydraulic method cost only about one-fourth to one-fifth of the ordinary way of building dams by means of sweepers and carts. The dam, as raised in 1898, is 28 feet wide on the crest and 500 feet long. The original width of the ravine at the base of the dam was 66 feet. The present width of the dam from toe to toe of slopes is 1,700 feet. The maximum depth of water to the silt in the reservoir was about 85 feet in 1902. A wasteway was originally excavated in the bed-rock of the natural hillside at the north end of the dam and was lined with masonry. Tt has been practically abandoned as menacing the safety of the dam, and was replaced in 1888 by a waste-tunnel, about 1oX10 feet in section and 1,487 feet long, having a 24 per-cent grade. This tunnel was driven through a ridge to the north of the dam and was lined throughout with masonry. The outlet-pipes are laid in two tunnels excavated at different elevations near the dam. No pipes or culverts were placed in the dam itself. The construction of this dam was chiefly due to Mr, Anthony Chabot of Oakland. It was probably due to his experience in hydraulic mining that a large part of the dam EARTHEN DAMS. 239 was constructed by the hydraulic method. Mr. W. F. Boardman, a hydraulic engineer of Oakland, California, superintended the construction of the dam. The Pilarcitos and San Andres Dams, California,* were constructed to form storage reservoirs for the City of San Francisco. The Pilarcitos Dam (Fig. 54) is 25 feet wide at the crest and 620 feet long. It is 95 feet high above the original surface of the ground. Its down-stream slope is 2}:1 and the up-stream slope is 3:1 for a certain distance at the bottom and then 24:1. The roe --" tek Conerete Wall 3x 6 Beale in fect eS SS Se uv 40 40 «GO 30-100 Fic. 54.[—CRoss-SECTION OF PILARCITOs Dam. dam is provided with a centre puddle-wall which extends down 4o feet below the surface into a trench cut in the rock, The reservoir formed by the dam, which is 696 feet above the sea-level, stores about 1,180,000,000 gallons. The San Andres Dam (Fig.55) is 25 feet wide on top and 850 feet long. Its up-stream aid down-stream slopes are respectively 3.5:1 and 3:1. Originally the dam was only Fic. 55.—CROSS-SECTION OF SAN ANDRES Dam. 77 feet high above the surface, but in 1875 it was built up 16 feet higher, giving it a height of 93 feet above the surface. The base of the dam, as finished in 1875, is 135 feet wide. The central puddle-wall extends through 46 feet of earth and gravel to bed-rock. As the up-stream slope was continued in the same plane in the raising of the dam, the puddle-wall had to be built at the top on an offset, as shown in Fig. 55, in order to keep it in the centre of the dam. The reservoir formed by the dam stores about 6,500,000,000 gallons. *Reservoirs for Irrigation, Water-power, and Demestic Water-supply,’’ by James D. Schuyler, M. Am. Soc. C. E. + Figs. 53 and s4 are taken from ‘‘ Earth Dams,” by Burr Bassell, M. Am. Soc. C. E. 240 DESIGN AND CONSTRUCTION OF DAMS. The Tabeaud Dam,* California, was constructed in 1900-02 by the Standard Electric Company, of California, as part of its electric development. It is located on a small tributary of the South Fork of Jackson Creek, about 8 miles above Jackson, the county seat of Amador County. The dam is about 2,000 feet above the sea-level and 1,256 feet above the company’s power-house, which was built at Electra, on the Montelumne River, about 13 miles from the dam. The principal dimensions of the dam are: Length of crest ......--...- Seeing ea ce Saedig tdi ouiays 636 feet. re ft Base. CLOSSing PAVING s44.airaicwrare-alierd aie sisiude Gewese’ 50-100 *S Height of dam above natural surface at down-stream toe... 123 Sf oe cc cé ce ce oe ce up-stream toe... ee I00 ce oe Ee ‘* rock vertically beneath crest......... ‘ 120 °° Superelevation of crest above high water in reservoir....... 8 Width. of dam at topos ccccstenoinesekecateyiedeguanece 20° Be CREE, SEE” SRY ID a Ges Se sesh asda nla te dea eae rat ecstasy att 620 ‘f Lotal volume: in. dams. occcusss waivigaed sees etecneaudanines 370,350 cubic yards. ei ‘A Jeeta Pa in, Excess of: is ea sat 20/, Crown El, 1258 ,*) Orginal Plan; Rock Paving % i spins Eng eels fa “sg” _7/ (a8*deep not aia, H.W.Surface, E1.1250.0 7 oF Tih 901 —— 3 a oe On. 1901 Bulz0. xo —— g B1:1206 25) coe : ‘puis oe Soom == . a Ses gn 5 Sept TMT yyggq DWT Ca. Vids. ae os = 3 Bine0 joy o_O ee = Bs ELu61, i 0 ELiey a = as ‘September Fill 1900 :, Beis Teen £1.1135 a) 1 Na SS © qe Yiock Drain Iu Bed Rook ‘Approx.Grade 1:25 4 SECTION A-B Fic. 56.—CRoss-SECTION oF TaBEAUD Dam. The dam forms a reservoir having a water surface of 40 acres and an available storage capacity of about 350,000,000 gallons. In addition to this the reservoir has a silting capacity of 1,091,000 cubic feet. Fig. 56 shows the cross-section of the dam. On both sides the general slope is 24:1, but, on the up-stream face, the lower half of the slope is flattened by a rock-fill, put over a puddle face, to 3:1 and on the down-stream face the slope is broken by three berms. According to the original plans the dam was to have a central puddle wall which was to be 8 feet thick at top. After this wall had been carried up to a height of 24 feet it was abandoned and a puddle slope protected by a rock-fill was substituted in its place. This was done, as the material placed in the dam proved to be very impervious, and also to expedite construction. Most of the dam rests on hard-pan and the balance on bed-rock, most of which is slate, having a dip of about 40° up-stream and a strike of 15° with the centre-line of the dam. The excavation was made to rock beneath both the axis and near the foot of the inner slope, where the puddle-face wall abutted against the hillsides. About 150 feet above the centre-line a quartz vein crosses the valley. Between this line and the longi- * Engineering News, July 10, 1902, and ‘‘Earth Dams," by Burr Bassell, M. Am. Soc. C. E. EARTHEN DAMS, 241 tudinal axis the rock was satisfactory, but above the quartz vein fissures and springs occurred. A system of drains was placed in the excavation in bed-rock in order to remove the water from the springs during construction and to intercept seepage after the reservoir was filled. The drains were generally made either with stone or of small pipes that were protected by inverted angle-irons. According to circumstances the drains were either covered with fine gravel or concrete and then with clay puddle. The main drain consists of an 11-inch iron pipe, which was laid to a weir-box outside of the down-stream slope at a distance of 500 feet from the axis of the dam. The embankment was made of a red gravelly clay, which was almost an ideal material for constructing a homogeneous dam. The puddle placed on the up-stream slope was only used to “make assurance doubly sure,” and was not extended to the top of the dam. As the upper surface of the slate bed-rock was found to be badly fissured, especially near the up-stream toe, and as the rock was not very deep below the surface, the excavation was made to bed-rock for the entire up-stream half of the dam. At the axis of the dam and where the puddle face abutted against the hillsides the excavation was also made to rock. The material placed in the dam was obtained near by from borrow-pits within the limits of the reservoir or at the ends of the dam. The surface of the ground was plowed and the earth was excavated. by means of a steam-shovel and scrapers, and loaded through earth traps into dump-wagons, each holding 3 cubic yards. The wagons, which weighed loaded about 6 tons each, were hauled by 4-horse teams, and the earth was dumped on the dam in long rows, through swinging bottom doors, while the wagons were in motion. These rows were generally parallel with the axis of the dam, except at the ends, where a few rows were made parallel with the intersection of the embankment with the hillsides. The best material was placed on the up-stream half of the dam and at the ends. After the earth was dumped, all roots, stones weighing over five pounds, and other unsuitable material were removed by rock-pickers, who were contin- ually passing along the rows with their carts. The rows were then leveled by 6-horse road- graders and the material was then harrowed and rolled, being sprinkled by water-wagons and by hose and nozzles, as required. The top of the dam was kept basin-shaped during the construction, with a slope of about 1 in 25 from the sides to the centre. This made the central part of the dam receive more water than the others, any excess being carried off by the drains in the foundation. The specifications required the body of the dam to be constructed in 6-inch layers up to a height of 60 feet and permitted 8-inch layers to be used above this elevation. The thickness of the layers was regulated closely by spacing the rows of earth. The top surface of every finished layer was thoroughly sprinkled and harrowed before the next layer was placed. Two rollers, each drawn by six horses, were kept constantly in use. One weighed five tons and the other 8 tons, the pressure per lineal inch for the rollers being, respectively, 166 and 200 pounds. The rollers were not grooved, but the smooth surface they left was always harrowed and more or less cut by the passing wagons, which when loaded had a pressure of 750 pounds per inch on their wheels. The wagons were found to compact the earth even more than the rollers. In the bottom trenches some tamping had to be 242 DESIGN AND CONSTRUCTION OF DAMS. done by hand and by the trampling of the horses. The trenches were made sufficiently wide to permit the horses to turn in order to have the material in the trenches tramped as much as possible. The outlet from the reservoir is a tunnel 2,903 feet long, which was driven through solid slate rock in the ridge dividing the watershed of Jackson Creek and Montelumne River. This tunnel is reached from the reservoir by an open cut 350 feet long and at the other end by a cut 39 feet long, each cut having a maximum depth of about 26 feet. The section of this tunnel consists of a rectangle, 6 feet wide by 4 feet high, on top of which there is a semicircle of 3 feet radius. The area of the cross-section of the tunnel contains about 40 square feet. The water from the reservoir fills the tunnel to a point near the south portal (the one farther from the reservoir), where a receiver is placed and connected with the tunnel by a short pipe-line, 60 inches in diameter. About 175 feet from the receiver a water-tight bulkhead of brick and concrete masonry is built in the tunnel. In the line of 60-inch riveted steel pipe, which connects the reservoir and tunnel with the receiver, there is placed a cast-iron chamber for entrapping silt or sand, with a branch pipe 16 inches in diameter, leading into a ravine, through which sand or silt thus collected can be wasted or washed out. All controlling devices, screens, gates, etc., are at the south end of the tunnel and easily accessible. The spillway is some distance from the dam. It consists of a cut, 48 feet wide at the bottom and 300 feet long, which was excavated through a hill and discharges into a ravine that joins the main valley 500 feet below the dam. The sill of the spillway is to feet below the top of the dam. The Tabeaud Dam, not including the foundation, was built in eight months, under the direction of Burr Bassell, M. Am. Soc. C. E. Dams for the Water-works of New York.—A number of earthen dams have been built in the Croton watershed to form, either alone or in connection with masonry dams, storage reservoirs for the water-works of New York. They have all been built with masonry core- walls, according to similar plans. The highest of these dams was built as an extension of the masonry dam forming the Titicus Reservoir, q.v. According to the contract plans, part of the New Croton Dam was to consist of an earthen embankment (see p. 163) which was to be constructed according to the cross-section shown in Plate XCIV, and the specifications given on page 367 of the Appendix, with its top 10 feet above the crest of the masonry dam. This embankment was to have a maxi- mum height of about 120 feet above the surface of the ground, a top width of 30 feet, and slopes on both sides of 2:1. The down-stream slope was to be broken by two berms, s feet wide, made, respectively, 30 and 60 feet below the top of the dam. The berms were to be ditched and paved to carry off rain-water. The up-stream slope was to be protected by a stone paving 2 feet deep, which was to be placed on 16 inches of broken stones. This paving was to extend to a level 10 feet above the high-water mark. The top of the dam, except where the roadway was to be formed, the up-stream slope above the paving, and the down-stream slope were to be covered with good soil and sodded. The construction of this embankment was carried on from the letting of the contract in August 1892, until the fall of too1. The discovery of some cracks in the core-wall EARTHEN DAMS. 243 of the dam, which was to have a maximum height of about 200 feet, gave rise to some apprehensions with reference to the water-tightness and safety of the embankment. Upon the recommendation of the then Chief Engineer, Wm. R. Hill, M. Am. Soc. C. E., the Aqueduct Commissioners, who had charge of the construction of the New Croton Dam, appointed, in June 1901, a Commission of Engineers to examine the plans for the construc- tion of the dam and to report what changes, if any, should be made. This Commission, which consisted of J. R. Croes, Edwin F. Smith, and Elnathan Sweet, all members of the Am. Soc. C. E., made a very careful examination of all the earth dams that had been built or were in construction in the Croton watershed. Specimens of the materials of which these embankments were made were examined with reference to impermeability in the Cornell hydraulic laboratory and pipes were driven in the inner and outer slopes to determine whether any water had percolated through the dams. The dams in the Croton watershed are made of glacial drift in which the materials are not evenly distributed so as to form a homogeneous mass. Distinct layers of gravel, boulders, and beds of sand occur in the borrow-pits from which the dams were made, and, also, large pockets of very fine sand, with a small amount of clay, forming a very compact material when not exposed to the action of water, but dissolving readily and becoming quite fluid when reached by water. In all dams on which observations were made the up-stream slopes were found to be completely saturated with water. In nearly every case water was also found in the down- stream slopes, but the extent of saturation in these slopes varied very greatly, according to the materials used and the care taken in the construction. In the case of the Titicus Dam (described on page 148) the core-wall proved to be impervious, no water being found in the outer slope of the embankment, until a depth of 40 feet below the reservoir level was reached. The presence of this water was readily accounted for by the supposition that there was a slight flow of ground-water from the natural surface which rises from the core-wall at this point and forms a pocket. When this confined water can escape to the toe of the embankment, it assumes a slope of 10.7 in 100, indicating that the embank- ment is quite porous. . In the outer slopes of the other dams examined the water appeared to be coming from the reservoirs, either by leakage through or under the core-walls, or through fissures in the rock. Water was found in the outer slopes of these dams at depths below high water varying from 7 to 26 feet, and was found to assume slopes varying from 17:100 to 40:100. The more compact the material in the embankment was the steeper the slope of saturation was found to be. As the result of its observations, the Commission reached the conclusion that in the case of the earth embankment of the New Croton Dam, whose crest was assumed to be 20 feet above high water, the loss of head caused by the core-wall would probably be 21 feet and that the slope of saturation would probably be 20 feet in 100 feet. On this basis the Commission did not consider it safe to construct the earth embankment of the New Croton Dam to a greater height than 7o feet. The Commission recommended that the core-wall and embankment of the New Croton Dam be removed and replaced by a masonry structure similar to that built for the main part of the dam. This recom- mendation was carried out by the Aqueduct Commissioners. 244 DESIGN AND CONSTRUCTION OF DAMS. The conclusions of the Commission were disputed by other prominent engineers, includ- ing A. Fteley, Past-President, Am. Soc. C. E., who had designed the New Croton Dam. The report of the Commission is given in full in the Enginecring Ncws of November 28, 1901, and the comments on this report by Mr. Fteley and other engineers are printed in the Enginxring News for 1901 and 1902. At the time tie change in the plans recommended by the Commission took place, more than half of the core-wall and about half of the earth embankment had been con- structed. The change made involved considerable expense and loss of time. The question whether this modification in the original plans was necessary is considered by Charles S. Gowen, who was Division Engineer in charge of the construction of the dam, in a paper read before the American Society of Civil Engineers in January 1906, and by a number of prominent engineers who discussed Mr. Gowen’s paper. The North Dike of the Wachusett Reservoir * was constructed in 1898-1905 to assist in retaining the water in the Wachusett Reservoir of the Metropolitan Water-works of Boston, Massachusetts. Tne dike is built across a sandy plain having a general level of about 15 feet below the water-l:vel of the reservoir. Its location was determined by numer- ous wash-drill borings. In all 1,131 borings were made, having an aggregate depth of 17? miles. The average depth to rock was 83 feet and the maximum depth was 286 feet. The north dike is of unusual dimensions. As it had been decided, upon sanitary grounds, to strip the surface soil from the whole of the 64 square miles comprised within the limits of the reservoir, a superabundance of material was available for the construction of the dike. It was decided, therefore, to give the dike an unusual width, ,in order to make percolation through it practically impossible and also to insure absolute safety. The dike has a length on the water side, at the full reservoir level, of about 2 miles. It covers an area of 143 acres and contains about 5,500,000 cubic yards of material. At the deepest place the dike is 65 feet high to the full-reservoir level and has a maximum width of 1,930 feet. The upper layers of the plain on which the dike was built consist generally of coarse sand or fine gravel. In order to prevent the percolation of water through these layers, a cut-off trench was excavated in such places, extending longitudinally under the crest of the dike. This trench has a total length of 9,556 feet, a bottom width of 30 feet, and a maximum depth of 60 feet. For 3,124 feet the trench was excavated in rock and for the remaining distance into fine sand. Wherever the material was such that percolation below the level of the cut-off trench was feared, sheet-piling was driven in the bottom of the cut-off trench. This sheeting was driven for 5,245 feet of the trench, leaving 1,187 feet of the trench without sheeting. The top of the dike was finished 17 feet above high water, allowing for a probable settling of 2 feet. The width of the dike at full-reservoir level is 189 feet. The down- stream slope is, as a rule, 3 in roo. But there are some exceptions, and at one place the slope is 6 in roo. On the water side the slope is 2 in 1, both above and below a berm 15 feet wide, which is made 13 feet below the full-reservoir level. Above the * Description by Frederick P. Stearns, Chief Engineer, in Trans, Am. Soc. C. E., Vol. XLVIII, page 259. See also Engineering News, May 8, 1902. EARTHEN DAMS. 245 berm the slope is protected by a layer of coarse gravel, 7 feet thick, resting on an embank- ment of either sand or gravel. Upon the coarse gravel a paving, 3 feet thick, of large stones embedded in and chinked with broken stones, is placed. This paving extends from 8 feet above the water-level to the berm, but diminishes in thickness towards its upper and lower ends. Below the berm the slope is only protected by a layer of coarse gravel, except in a few exposed places where riprap is used. ; The cut-off trench was excavated with slopes of 1:1, as this was found to be more economical than vertical sides and facilitated the work of driving the sheet-piles. This trench furnished most of the sand and gravel that was placed in the dike at its water side. A secondary cut-off trench of somewhat smaller dimensions was provided for a part of the length of thedike, as an additional precaution. The cut-off trenches were refilled with soil compacted by being saturated with water, which experiments showed to be prac- tically water-tight. The preliminary borings showed that in some places fine sands that were not wholly impervious extended to a depth of 50 feet below the bottom of the cut-off trench. As the sand was free of stones the sheet-piles were driven by means of a water-jet. It was found to be impracticable to obtain single planks for such long sheet-piles, and, where the length exceeded 30 feet, the sheeting was made 6 inches thick and composed of 2-inch planks put together substantially as the Wakefield triple-lap sheet-piling. The planks were planed to an even thickness and nailed together, except at the lower end, where they were bolted together to resist water pressure. The piles were beveled at the bottom for a part of their width to make them keep close to the piles against which they were driven. For lengths of less than 30 feet, 4-inch grooved spruce sheeting was used. In making the preliminary investigations for the construction of the dam numerous experiments ‘vere made upon the filtration of water through soils and sand, on the density of soil compacted in various ways and on the stability of soils under heavy loads. Experiments were also made with dikes which were built in a water-tight wooden tank, 6 feet wide, 8 feet high, and 60 feet long, which was constructed in a building, 25 feet wide by 70 feet long. The soil was deposited in the dikes in different ways: (1) Shoveled loosely into the tank without consolidation of any kind; (2) deposited by shoveling the soil into water. Water was admitted to one side of the dike experimented on, and the amount of percolation measured on the other side. It was found that soil that had been thrown in loosely in a dike settled, as it became saturated with water, and became quite compact. After the dike had been subjected to water pressure for several weeks, the percolation amounted to only 1 gallon in 22 minutes. The work was constructed under the direction of Frederick P. Stearns, M. Am. Soc. C. E., Chief Engineer of the Metropolitan Water and Sewerage Board of Boston, Massachusetts. The Belle Fourche Dam* (Plate XCV) is now being constructed across Owl Creek, just below the mouth of Dry Creek, about ten miles northeast of the town of Belle Fourche, South Dakota. It will form a reservoir for storing water for irrigation, having a capacity of about 66,500,000,000 gallons. - Fourth Annual Report of the Reclamation Service of the United States Geological Survey 246 DESIGN AND CONSTRUCTION OF DAMS. The dam will be 6,500 feet long and 20 feet wide on top. Its maximum height above the bed of Owl Creek will be 115 feet. The up-stream slope will be 2:1 below the highest water-level and 1:1 above this elevation. It will be protected from wash and ice action by 2 feet of screened gravel, rolled into place on the slope, on which concrete blocks, 4’x6’ and 8 inches thick, will be placed. The down-stream slope will be 2:1 in the lower portion and 1.75:1 in the upper portion. It will be provided with concrete gutters for disposing of the rainfall and will be fertilized and seeded with grass to prevent erosion. The dam will be made of heavy clay and gumbo, weighing in some places 120 pounds per cubic foot, and will be built in layers, the material being sprinkled and rolled with heavy steam-rollers. The reservoir will have two outlet conduits of concrete and steel, surmounted with towers and gatehouses for delivering the water into two distributing canals, known respec- tively as the north and the south canal. A semicircular waste-weir of concrete will be provided at the high-water line beyond the north end of the dam, ‘ The contract for the construction of the dam was given on November 14, 1905, to Orman & Crook of Pueblo, Colorado, and up to March 1, 1907, 94 per cent of the work of constructing the dam had been performed. The work is being done under the direction of the United States Reclamation Service, of which F. H. Newell, M. Am. Soc. C. E., is Director, and A. P. Davis, M. Am. Soc. C. E., is Chief Engineer. Charles E. Wells, M. Am. Soc. C. E., is Supervising Engineer, and Raymond F. Walter is the Engineer in charge of the Project. The dam is being built under the superintendence of Walter W. Patch, Assoc. M. Am. Soc. C. E., Constructing Engineer, at Orman, South Dakota. Failures of Earthen Dams have been very numerous. The cause of the rupture has generally been a neglect of some detail in the construction,—as an insufficient length of spillway or of the waste channel below it, a faulty manner of laying the outlet-pipes in the dam, etc. The two greatest disasters resulting from the failure of earthen dams occurred in Sheffield, England, on March 11, 1864, and in Johnstown, Pennsylvania, on May 31, 1889. As they teach some important lessons, we shall describe briefly the facts connected with these failures. The Dale Dyke Dam formed the Bradfield reservoir for the water-supply of Sheffield. This reservoir covered 78 acres and stored 114,000,000 cubic feet. The dam was 95 feet high, 1254 feet long, 12 feet wide on top, and 500 feet at the base. Both slopes were 24 to 1. The puddle-core was 4 feet wide on top and 16 feet at the surface, both faces being battered 1% inches per foot. To reach an impermeable stratum the puddle-trench was excavated for a great part of its length to a depth of 60 feet. Two 18-inch socket-jointed cast-iron outlet-pipes (14 inches thick) were laid naked in a trench under the dam at its highest point. The pipes were placed 2 feet 6 inches apart. The whole -rench was refilled with puddle, 18 inches of this material being placed both below and above the pipes. Where this trench crossed that of the puddle- core of the dam, it was excavated to the depth of the latter. EARTHEN DAMS. 247 In constructing the dam, the engineers adopted the rather original plan of making the inner part of the embankment as much as possible of rubble-stone and shale.* They based this preference on the idea that earth becomes saturated by water and assumes a flatter slope, while a pervious bank, made principally of stone, will keep its slope. By this arrangement, however, the whole hydrostatic pressure of the water was brought directly against the puddle-core. If settling caused the least crack in this puddle, the water was sure to find its way rapidly through the dam. While the puddle-core is to act as a cut-off in the heart of the bank, an inner slope of well: packed earth should prevent the water from percolating to the centre of the dam, as much as possible. The reservoir was full when the dam failed, and a narrow crack had appeared on the outer slope. In the investigation which followed the rupture of the dam, the greatest engineers of England testified as experts. Their opinions, as regards the cause of the bursting of the dam, varied very much, and it will never be known what started the failure. It is evident, however, that the plans of the dam were very unsafe in requiring the outlet-pipes to be laid unprotected in the dam, and the inner part of the dam to be made of stone and shale. The Johnstown Disaster, which caused the loss of more than two thousand lives and of millions of dollars’ worth of property, resulted from the rupture of an earthen dam which was built across the south branch of the Little Conemaugh River in Pennsylvania, The dam was 70 feet high, and 10 feet wide on top. The inner and outer slopes were respectively 2 to 1 and 14 to 1. In this case the inner slope was made of earth properly rolled, but stone was placed in the outer slope. The failure, which occurred after an unprecedented rain-storm, was due to the insufficiency of the waste-weir, which was partly obstructed by fish-screens. At 11.30 A.M. the water commenced to pass over the top of the dam, and it rose to a height of 20 inches above the dam. The water gradually cut a channel through the embankment, until at 3 P.M. the dam burst. If this dam had been provided with a masonry core-wall, carried up to the high- water mark, the water, instead of cutting a channel through the bank, would have washed away the earth to the top of the core-wall. This wall would have formed a long waste-weir which would not have been ruptured until the outer slope was washed away, and even then only the highest part of the wall might have given way. Considering the fact that the outer slope of the dam was made largely of stone, it is quite probable that the Johnstown disaster would not have occurred if the dam had had a core-wall. Such a wall, besides making a dam water-tight, may be considered as a safeguard against the erosive action of water that may pass over the top of a dam during a great flood. * See ‘‘The Designing and Construction of Storage Reservoirs,” by Arthur Jacob, B.A. 248 DESIGN AND CONSTRUCTION OF DAMS. CHAPTER II. DAMS MADE BY THE HYDRAULIC PROCESS. A NOVEL manner of building dams of earth and gravel has been used in some of the Western States. It consists in excavating, transporting, and depositing the material required by the erosive action of water, which is obtained either under pressure from a jet or by gravity from a flume. This method, which was first introduced for what is known as “hydraulic mining,” was soon applied in making small dams in California and was used, also, on a very extensive scale, in making embankments for the Northern Pacific and Canadian Pacific Railways. The dams of the Temescal and San Leandro storage-reservoirs for the water-supply of Oakland, California, were partly constructed in this manner (see preceding chapter), and within the last few years a number of dams in the Western States have been constructed by this process. According to James D. Schuyler,* M. Am. Soc. C. E., the theory on which such dams are generally planned is: First: That the inner third of the dam should be composed of material which should consolidate into a mass impervious to water. Second: That the outer half of each of the other thirds of the dam should consist of coarse, porous material, permitting the passage of water, and Third: That the inner halves of the outer thirds of the dam should be a mixture of coarse and fine material, which should act as a filter to retain the fine particles of the inner third, while allowing water to percolate slowly. In order to carry on the hydraulic process of dam construction efficiently, water should be obtained by gravity in a volume of 10 to 15 cubic feet per second, with a pressure of roo to 150 pounds per square inch at the nozzle of the monitor (the name given to the hydraulic machine used in this method). The earth eroded by the water at the borrow-pit is sluiced to the dam in a flume or pipe which is carried across the valley at the site of the dam on a light trestle. Lateral flumes or pipes are placed at suitable distances to distribute the sluiced material to the differ- ent parts of the dam. The Dam at Tyler, Texas, was built in 1894 by the hydraulic process. The dam is 575 feet long and 32 feet high. The inner and outer slopes are respectively 3 to 1 and 2 to 1. The maximum depth of the water in the reservoir is 26 feet. All the material used in the dam was sluiced in from a hill near by. ‘The average cost of the * Paper on “Recent Practice in Hydraulic-fill Dam Construction” in Trans. Am. Soc. C. E,, June 1907. x PLATE BEGINNING THE CONSTRUCTION OF LA MEsA Dam. (From “Eighteenth Annual Report of tT. S. Geological Survey.”’) DAMS MADE BY THE HYDRAULIC PROCESS. 25r dam, including the plant and all the appurtenances of the reservoir, was 4% cents per cubic yard. In this case the water required for sluicing was obtained from a 6-inch pipe from the old city pumping-station. This pipe terminated with a common fire-hydrant about half-way up the hill from which the earth was to be washed. An ordinary 2-}inch hose, with a nozzle 14 inches in diameter, was connected with the hydrant and delivered the water, at the place where it was required, under a pressure of 100 pounds per square inch. The stream from the nozzle was directed against the face of the hill. The cutting made by the jet was carried into the hill on a 3 per cent grade. A working- face of 10 feet high was soon obtained and gradually increased to 36 feet. The jet was directed against the face so as to undermine it, and the water washed the material (clay, sand, and loam) to the dam. About 65 per cent of this material was sand, and 35 per cent clay and loam. The work on the dam was begun by digging a trench 4 feet wide from the surface down into the clay subsoil, a depth of several feet. This trench was then filled with selected puddle-clay which was sluiced into place. The slopes of the dam were then defined by low ridges made by the laborers with hoes, and a flow of water carrying sand and clay was maintained over the top of the dam, the water being drawn off from time to time at either slope. The material was conveyed from the bank in a 13-inch sheet-iron pipe having loose joints, stove-pipe fashion. This pipe extended from the bank to and across the dam on its centre-line. The joints could be readily uncoupled and the stream directed so as to carry the bank up uniformly. The quantity of solids brought down by the water was found to vary from 18 per cent in clay to 30 per cent in sand. As sharp sand does not flow as readily as rounded sand’ or gravel, the delivery was increased by mixing clay and stones with the sand. The entire cost of this dam is given as $1140. The reservoir formed by it covers 17.7 acres and stores about 77,000,000 gallons. The dam is reported to be water-tight. La Mesa Dam, California, was constructed in 1895 to store the flood-water of San Diego River. The dam (Fig. 57) is 66 feet high, 20 feet wide on top, and & aes ~ & é 8 gP Fine sand Vee go._Lime ahd Clay PS Caer sas Oo Top eo See RR Ot N z $ Vo on wd o % ‘ad me 4 $ A ‘ \ h H a % 409; n S fo v rN ' 8 g ° % § of 8 Finesand a] ‘ ‘ ww OG oad Mud 55 es wi 2! 75" aah 25! ' Fic 57.—Cross-sEcTION OF LA MEsA Dam. 251.5 feet at the base. It consists partly of a rock-fill and partly of a bank of earth, The material was transported and deposited in the fill by water by the process 252 DESIGN AND CONSTRUCTION OF DAMS. known to miners as ‘‘ ground-slnicing.’’ The surplus water from a flume of the San Diego Flume Company was used for the purpose and was stored in the reservoir as the fill rose in height. The dam is located in a very narrow gorge cut through porphyry. The valley is only 40 feet wide at the bottom, and one side is almost vertical for 40 feet. According to the original plans a rock-fill with plank-facing was to be built at this site. This dam was to be 55 feet high. Its top-width was to be 12 feet, and the up-stream and down-stream slopes were to be respectively 4 to 1 and 1 to 1. The length on top was to be 470 feet. The lowest bid received for building this dam, exclusive of the plank facing, outlet-pipes, and gates, was $20,260. As a lower bid was received for building a dam by the hydraulic process, that method was adopted and the dam was built at a total cost of about $17,000, including plant, excavation of foundations and spillway, outlet-pipes, culvert and stand-pipes, paving of slopes, etc. About 38,000 cubic yards of material was put in the dam. It was obtained by stripping I1.5 acres, situated about 2200 feet from the dam, a mean depth of 2 feet. Below the depth of 2 feet the material was found to consist of gravel and cobbles, which were cemented together so hard as to resist washing. This necessitated the use of scrapers to bring the material to the sluiceway and increased the cost considerably. If all the material could have been transported directly by the hydraulic process, the dam would probably have cost 25 to 30 per cent less. The gravel put in the dam varies from egg size to cobbles 8 to 10 inches in diameter. The largest cobbles were laid by hand on the outer slope so as to form a dry wall of uniform batter. The amotnt of water available for building the dam was only from 300 to 400 miner’s inches (6 to 8 second-feet). From the end of the flume from which the supply was obtained, the water was siphoned across a deep ravine in a 36-inch wooden-stave pipe, 3000 feet long, which emptied into a ditch 1.5 miles long, extending to the top of the ridge on the south side of the dam. Lateral ditches were carried from various points on the main ditch down the slope on 6 per cent grades. They divided the ground into irregular zones, 50 to 100 feet in width and several hundred feet long. These divisions were stripped to the rock, beginning next to the dam and working towards the ridge. The fall from the upper (clear-water) ditch to the lower side of a zone was made as great as possible. When the slope became flatter than 1 in 4, the velocity of the water was reduced so as to become insufficient to erode the material. In such cases the hydraulic process had to be assisted by the use of scrapers and ploughs, where the ground was not too soft for teams, or by hand labor. The stream of water carrying its load of earth and gravel was conveyed-along the line of the lower ditch through a 24-inch wooden-stave pipe to the fill where the material was to be deposited. This pipe was found to wear out very rapidly and had to be lined with strap-iron or tire-steel. Cast-iron pipes would have been preferable for this kind of work. An embankment made by this process becomes so thoroughly compacted that no rolling is required to prevent settling. In building this dam a force of 27 to 45 men, divided into three 8-hour shifts, placed 700 to 1400 cubic yards a day. Two men were always kept on the dump directing the stream of material, the DAMS MADE BY THE HYDRAULIC PROCESS. 253 other laborers being needed for the ground-sluicing. The upper 12 to 15 feet of the dam was finished by hauling in material with wagons. Before beginning the dam a trench, 2 to § feet deep, 20 feet wide at the centre, and 5 feet wide at the ends, was excavated to the bed-rock on the longitudinal axis of the dam. The material excavated from the trench was thrown on both sides and forms part of the embankment. Water is drawn from the reservoir through two lines of 24-inch cast-iron pipes, which extend through the dam at its widest part, for 72 feet from the outer toe, and connect with a concrete conduit (48 inches wide and 30 inches high) which connects with the reservoir. Four stand-pipes, consisting of 24-inch vitrified pipes, which are surrounded with concrete, connect with the conduit. Their tops are placed at different levels. Each of these stand-pipes is provided on top with a brass ring and flap-valve, which is operated from the top of the dam by means of rods, laid on the inner slope. During the construction of the work these pipes served to admit the water into the reservoir after it had deposited its load of gravel and sediment. The pipes were carried up a joint (2 feet) at a time. As the stand-pipes are placed on the inner slope, the coarser material was deposited by the water in the outer slope, and the fine sand at the reservoir. This is just as it should be. An advantage of making a dam by the hydraulic process is that the work is tested, as it progresses, by the pond of water that collects behind it. This dam is not free of leakage. With 46 feet of water the loss amounted to only 23 gallons per minute, but it increased to 100 gallons per minute when the water reached the 54-foot level. It is intended to cover the water-slope with a facing of asphaltum cement concrete. Recent Hydraulic-fill Dams.—In a paper presented, on December 19, 1906, to the Ameri- can Society of Civil Engineers, James D. Schuyler, M. Amer. Soc. C. E., gives an interesting account of “‘recent practice in hydraulic-fill dam construction.”” The following descriptions of dams repaired or built by the hydraulic method are condensed from Mr. Schuyler’s valuable paper. The Lake Frances Dam was constructed in 1899 on Dobbins Creek, in Yuba County, Calli- fornia, to form a reservoir of 228,500,000 gallons capacity. The watershed supplying the reservoir has a yield varying from practically nothing to 1000 cubic feet per second. On October 21, 1899, a few days after the dam had been completed, a rainfall of 9 inches in 36 hours occurred, which caused the reservoir to fill very rapidly. When the water had risen to-within 6 feet of the spillway the dam was ruptured at a point where it had settled, a gap being formed in the dam 98 feet wide, measured on the crest, and 30 to 4o feet wide at the bottom. In 1go1 this gap was filled by the hydraulic sluicing process and the dam was raised an additional height of 27 feet by the same method. As originally constructed the dam had a height of 50 feet, a length on top of gg2 feet, and slopes of 2 to 1 and 3 to 1, respectively, on the down-stream and up-stream sides. The crest of the dam, which was carried up 4 feet above the spillway, was 16 feet wide. The spillway, which 254 DESIGN AND CONSTRUCTION OF DAMS. was excavated in earth and lined with a wooden flume of 2-inch plank, had a width of 4o feet. The outlets of the dam consisted of two 36” cast-iron pipes laid in trenches 15 feet apart from centre to centre, about 100 feet east of the creek-bed, and a 16-inch riveted steel scour-pipe laid at a lower clevation in the creck channel. The sluice-gates of these pipes were operated from light steel towers standing in the water of the reservoir. For two thirds of its length from the south end the dam was built with slip and wheel scrapers and rolled in the usual manner. For the remaining part, which was built late in the season after the water-supply had practically failed, no attempt was made to place the filling in layers. Towards the end there was such haste to complete the dam that the earth was dumped in the most convenient manner, as in an ordinary railroad embankment. Much of the steep slope on which the dam was constructed at its north end was not cleared of stumps and roots. The earth of which the dam was constructed consisted of red clay and gray sandy soil resulting from the disintegration of syenite devoid of mica. When the dam was ruptured, the first symptom noticed was considerable leakage along the outlet-pipes. A few minutes later, a large stream appeared near the steep bank, about 100 feet west of the original creek channel and 20 feet above the base of the dam. This stream enlarged very rapidly and washed away about 20 per cent of the material of which the dam had been constructed. Some of the cast-iron outlet-pipes were broken by the pressure of the earth and the softening of the foundation under them. In 1900 James D. Schuyler, M. Am. Soc. C. E., was engaged to report on the best manner of repairing the dam. He associated with himself J. M. Howells, M. Am. Soc. C. E., who was assisted by F. S. Hyde, Hydraulic Engineer, who had been in charge cf the construction of the La Mesa Dam in California. These engineers deemed it unwise to repair the dam by simply filling in the gap, as it was liable to fail at some other point, and, as unequal settlement would occur between the cld and the new part, they recommended that a heavy layer of earth be placed against the up-stream slope, of sufficient thickness to give an impervious core of selected fine clay between porous zones of coarse, stable material, one of which, next to the dam, should be of sufficient thickness to drain properly the clay core down along the slope of the old embankment to a stone drain, which was to be carried along its upper toe and connected with a drainage-pipe. An outer permeable layer cf stone and sand was required to give stability to the 3 to 1 slope of the outer face. These three layers were to have an aggregate thickness of 125 feet, measured horizontally. As this plan would give the dam a crest width of 141 feet, it was recommended that its height be increased by 27 feet, the storage of the reservoir being thus increased to about 760,000,000 gallons. With the proposed increase in height the length of the dam along the crest was to be 1,300 feet. It was recommended that the width of the spillway be increased to 80 feet, in addition to a five- foot culvert through the dam, near the bottom, which was to be opened during floods, and that the crest of the dam be raised 6 feet above the spillway. These recommendations were accepted and the repairs and raising of the dam were carried out in rgo1 to 1905, under the immediate direc- tion of Mr. Hyde. The only available water was to be found in Dobbins Creek, the flow of which is reduced during the dry months to 1 cubic foot per second, and is at times a mere trickle. A small crib-dam was built about 300 feet below the main dam, and 150,000 gallons were stored before the sluicing began. At first the water was raised to the monitor by means of a 6-inch single-stage centrifugal pump, DAMS MADE BY THE HYDRAULIC PROCESS. 255 which was direct connected to a 30-h.p. motor, supplied with electricity from a power-house two miles distant. This pump delivered 1.76 cubic feet per second under a head of 100 feet. The water sluiced, through 11-inch pipes, 4,090 cubic yards of earth into place from a hill near by at an expense of 18.27 cents per cubic yard. The average ratio of solids deposited to water pumped was 13 per cent. The muddy water draining from the dam and overflowing from within the levees, thrown upon each slope in the break, after depositing its load of earth, was caught in the little reservoir below and pumped over and over again. The small centrifugal pump was soon replaced by a two-stage tandem centrifugal pump capa- ble of delivering 6 cubic feet per second under a pressure of 120 lbs. per square inch. The water was delivered through a line of 20-inch pipe, varying from 300 to 700 feet in length, and the material was sluiced to the dam through a 22-inch riveted pipe laid on a grade of 3 per cent. This pipe was carried across the dam, on a grade of 2.2 per cent, on a trestle having an average height of about 25 feet. It was erected on a line parallel with the axis of the dam, and far enough inside of the slope lines to make it possible to reach the slope with lateral flumes of moderate length. The posts of the trestle were left in the embankment. Owing to the great length of the dam and to the fact that all material had to be obtained from one side, very low gradients had to be adopted for the sluice-pipes. This made it impossible to use much of the rock found in the borrow-pits. Most of the material sluiced was clay. As not enough rcck and gravcl was deposited in the dam to kecp the slopes frcm slipping and sloughiing, brush had finally to be resorted to to maintain the slopes while the embankment was settling and draining. Pine and cedar boughs and young trees about 6 fect long were laid, with the butts towards the centre-line of the dam, in the low levees that were thrown up on either side of the dam. Although this gave the slopes of the dam a rough appearance, it stopped the sloughing and shding. During the construction a pond of water and thin mud, 1 to 5 feet deep, was maintained on top of the rising dam, and the reservoir was allowed to fill behind the dam, the water-level being kept 8 to 11 feet below the top of the dam. For a detailed account of how the dam was repaired the reader is referred to the paper of James D. Schuyler, M. Am. Soc. C. E., mentioned above. The Crane Valley Dam was constructed by the San Joaquin Electric Company in Madéra County, Central California, by the hydraulic process, in order to form a storage reservoir. The dam was located in the lower end of Crane Valley, where this valley contracts into a narrow canyon, through which the North Fork River flows. The plans for the dam were prepared by J. M. Howells, M. Am. Soc. C. E., in the capacity of Consulting Engineer, and the construction was carried on under the direct supervision of the President of the Electric Company, Mr. J. J. Seymour. The general dimensions of the dam were fixed as follows: Maximunt height ..:.06. s02 cane ceteen cue dm oie weadaeene 100 feet. ene tly On top ides astaie dawewuen sowie eee cand Sele dees eaies 720 * Width, On tops: cust tect eecaego gee ete steen Dees emtendides 0 Slope on NEE Cea seat ine catenigamnegiy Ceeaacnsamwees oi Width-of canyon at base, o:...3 ee vis see akavadseevedeeseee ds 50 * EP’ “GO MECE ITE eT wy shece ie col oye sara fate iar pire ae oie ate 200 256 DESIGN AND CONSTR.CTION OF DAMS. The bottom and sides of the canyon are composed of granite formation. Near the stream the rock is extremely hard, but it becomes less so as the sides recede, and near the top, on the west side, it was difficult to obtain a sufficiently firm base for the foundation of the centre core of the dam. The centre-line of the dam was excavated to bed-rock, and all loose material, boulders, and sand resting on the rock were removed on the up-stream side for a distance of about 20 feet from the centre- line. A concrete foundation-wall, 2 feet thick and 2 feet high, was then built along the centre-line. ‘This wall was made 5 feet high in the centre of the stream-bed. About g inches from the up-stream side of this wall a wooden core-wall of doubled 1-inch sheeting was fastened by firmly embedding it with concrete of high grade. This sheeting was carried up about 30 feet above the bottom of the dam. Its principal object was to prevent the stratification of the material deposited by the hydraulic process from extending across the centre of the dam. After the dam was constructed it also served to prevent water from percolating through the core of the dam. According to the original plans, the wooden core-wall was to be carried up to the water-line of the reservoir, but it was found that stratification of the deposited material could be effectively prevented by a system of cutting into the plastic material in the central part of the dam by pushing down board paddles made of 1-inch boards. When sluicing was being carried on, continuous lines of cleavage were made in the centre plastic material by means of the paddle, from end to nd of the dam. These lines of cleavage were made at intervals of 2 feet on the up-stream side, from the centre-line for a distance of 20 feet, making in all 8 or 10 lines of cleavage each time the process was gone through. In doing this work the paddles could be pushed about 10 feet into the mushy middle mass, so that the cleavage was repeated over and over again. The result obtained by this kneading process was so satisfactory that it was not considered necessary to carry the wooden sheeting higher than 30 feet from the bottom. ‘Towards the sides of the canyon the height of the sheeting was gradually decreased until, at an elevation of 60 feet above the bottom, it extended only 6 feet above the foun- dation-wall, which height was maintained to the ends of the dam. A 3-inch porous cement conduit was laid on top of the centre concrete wall, against the down- stream side of the wooden sheeting, for the whole length of the wall. This conduit was connected at the lowest point in the stream-bed with a 6-inch porous cement pipe, which was laid down the stream-bed until it extended beyond the toe of the lower slope. The object of this drainage system was to draw off any water that might percolate past the centre of the dam. During the construction the water of the stream was carried off through a cut, 6 feet wide and 7 feet high, that was blasted out in solid rock at a level of 14 feet above the stream-bed, and was arched over with masonry. Gates were set in this culvert on the centre-line of the dam. After the completion of the dam the culvert was to be bulkheaded just above the gates, which could then be closed, allowing the water-storage to begin. A circular shaft, 22 inches in diameter, made of successive rings of cement pipe 12 inches in height, was carried up directly above the gates to the top of the dam. During the construction the water used in the sluicing, which formed a pool in the centre of the dam, was drawn off through this shaft. The water needed for the hydraulic process was pumped from the stream by a Worthington compound duplex pump, capable of pumping 60,000 gallons per hour (2} cubic feet per second). The water was conveyed through an 11-inch riveted steel pipe to a “Little Giant” monitor, having a nozzle of 2} inches diameter, which was placed at the borrow-pits, 75 to 110 feet above the stream. Flumes laid on a 6-per-cent grade carried the earth washed out of the borrow-pits to the dam. The DAMS MADE BY THE HYDRAULIC PROCESS. 257 flumes were made of 1-inch pine lumber 12 inches wide, and had an inner cross-section 10 inches wide by 12 inches high. They were enclosed on all four sides until the dam was reached, where the top board was left off. Grades of less than 6 per cent were found to cause clogging of the flumes. Two flumes were constructed on the dam, one on each side. They were used alternately in the sluicing operations, one side of the dam being carried up a certain height and then the other. The flumes were supported on light trestles, made of 2’’x4’’ plank. They were raised about 10 feet in elevation each time. Slotted openings were made in the bottom of the flume, through which a driblet of water was allowed to run, that carried with it the coarser particles of sand coming down the flume. This material was shoveled out by the workmen to carry up the outer slopes of the dam. Attempts were made to carry small boulders and rock through the flumes, but this was found to be impracticable with the available quantity of water and with the grades used. About two thirds of the total quantity of material placed in the dam was moved very cheaply by the method of pumping and sluicing described above. For the last third of the material to be placed in the dam water was brought by gravity in ditches from a distance of five miles, and the earth was ground-sluiced in, the methods of handling the sluice being similar to that of pumping. The dam was brought up to a height of about 70 feet, which gave sufficient reservoir capacity for the needs of the company at that time. At this elevation a secure temporary spillway was obtained. Both faces of the dam were riprapped with broken stone gathered from the adjoining hillsides and from the temporary spillway. During the construction of the dam some blasting had to be done at the outlet of the culvert. This caused a break in the 3-inch drainage-pipe, described above, at the point where this pipe crossed the outlet-culvert. This led to a break in the dam, which began by showing an increase and discoloration of the small quantity of water that was carried by the 6-inch drainage-pipe to a point below the toe of the lower slope of the dam. This flow increased to 3 or 4 miner’s inches of highly discolored water carrying much sand, which quantity was discharged for several days. At this time the reservoir was almost full to the spillway, with the outlet-culvert discharging its full capacity of water. As the result of washing out of material in the dam a subsidence occurred on the top of the dam, about 4o feet from the centre, on the up-stream side and a little to one side vertically of the outlet-culvert. The subsidence continued until a conical-shaped depression, 15 to 20 feet deep, had been made. Several concentric rings of fracture occurred around this crater, the outermost being nearly 60 feet from the centre of the disturbance. In order to repair the break great quantities of gravel, boulders of varying sizes, and bags of sand were thrown into the break, and were supposed to have checked the leak, as it gradually stopped. To repair the break a shaft was sunk around the 22-inch cement pipe-shaft, through which the water had been drained off during the sluicing. Some of the sections of this pipe were found to be broken by the movement of the top of the dam towards the depression. When the top of the culvert was reached by the shaft it was found that the 3-inch drain-pipe had been plugged with roots and leaves which had been washed into the dam in the process of sluicing. This drain-pipe was plugged with cement, the circular drainage-shaft was removed, its opening into the culvert being closed, and the exploration-shaft was filled up. The reservoir has been in use since its completion, but the dam has not been brought up, at this date, to the height originally contemplated, namely, too feet. 258 DESIGN AND CONSTRUCTION OF DAMS. Hydraulic-fill and Rock-fill Dams on Snake River, Idaho.—Three dams were built in 1904-1905 by the Twin Falls Land and Water Company to divert Snake River into irriga- tion canals, on either side of that stream, in Cassia County, Idaho. The plans for the work were prepared by W. G. Filer, Manager of the Company, and P. S. A. Brickel, Chief Engineer, with the advice of James D. Schuyler, M. Am. Soc. C. E., as Consulting Engineer. At the site selected for the dam, the river was divided by two islands of basaltic rock into three channels. The north channel was the permanent bed of the river, the middle channel carried a considerable volume of water at medium high water, while the south channel carried water only during exceptionally high floods. The three channels were closed by earth and rock-fill dams, which raised the river g feet above normal low water. The islands were utilized for wasteways. The principal dimensions of the dams are: Peeing Top Height above ee Length. Lower Toe. Rock-fill. Earth. Main channel. . . . . . 340 ft. 86 ft. 39,650 cu. yds. 58,000 cu. yds. Middle channel , « » » + 835 81 42,800 62,850 South channel. . . . . . 560 56 34,700 48,000 The total length of the three dams and the spillway is about 2,100 feet. The rock-fill parts of the dams were made 10 feet wide at the crest, with slopes 14 to 1 on the down-stream side, and } to 1 on the up-stream side. After the base of each dam had been stripped of surface soil and loose material, a trench, 5 to 6 feet wide, was excavated into the bed-rock along the centre-line of the rock-fill, extending up to the top on the sides. A continuous core-wall of double 2-inch plank was built in the trench from the bottom to within 6 feet of the top. The planks were laid horizontally, breaking joints, and were spiked to 3’ x 6’ uprights, placed 2 feet. apart from centre to centre. The base of this wooden core-wall was embedded in concrete, which filled the trench to above the line of the bed-rock and formed a tight bond with the rock. The loose rock-fill was built up on each side of the core-wall, which was carried up considerably in advance of the rock-filling. For several feet on each side of the core-wall the rock was carefully laid by hand, but beyond this it was loosely dumped from a cableway. The object of the core- wall was to prevent the earth sluiced against the up-stream side of the rock-fill from flowing through the voids in the rock. The earth available for the dam consisted of fine, white or grayish soil, which covers this region to a depth of from 2 to 20 feet. It is almost impalpable powder, free from grit and very uniform, which is classified by geologists as loess or eolian (wind-borne) soil. It absorbs water very slowly, but packs very solidly after becoming wet, and becomes as imper- vious as solid clay, without having the disadvantage of clay of shrinking and cracking as it dries. In constructing the south and middle embankments, a levee was thrown up with dry earth at the up-stream toe of the fill. The earth used for this purpose was hauled by wheel-scrapers or wagons. The bulk of the filling between the levee and the rock-fill was sluiced in place by water delivered by a centrifugal pump from the river to the earth-dump at one end of the dam. The earth required was brought by cars from borrow-pits and dumped at such an elevation, at the nearer end of the dam, that the water would carry it to the other end. Earth sluiced in this manner forms a grade of 2 to4 percent. All the voids on the up-stream side of the rock-fill were filled with liquid mud. Some slight leakage occurred in the wooden core-wall, but this was soon stopped by the swelling of the wood. The earth embankment was always kept about 20 feet below the top of DAMS MADE BY THE HYDRAULIC PROCESS. 253 the rock-fill. While the earth was being sluiced-in it was so soft that a puie coula easily be pushed down 10 feet or more into the mud, but after drying for four days it became so hard that a team could be driven over it without sinking in. About 1.5 cubic feet of water per second was used for sluicing the earth. It was sprayed upon the dusty earth coming from the cars, and converted it almost immediately into liquid mud. After depositing its material the water soon disappeared in some mysterious manner, without reappearing at either slope of the dam, being partly absorbed by the dry earth at the outer slope. About 80 per cent of the volume of the middle and south dams was made by the hydraulic process, only 20 per cent being put in dry at the outer slope. The dams showed no leakage when the reservoir was filled. A somewhat different method of construction had to be employed for the north dam, which was built in the bed of the main stream, where the flow amounted to 5,000 to 10,000 cubic feet per second, during the construction. The water was diverted into a large tunnel, which was driven at the north end of the south island, next to the middle dam. When the work on the dam was begun, the water in the north channel was 20 feet deep. Two parallel fills of large, loose rock were made, by means of a cableway, across the channel, to form the outer toe-walls for the rock-fill. Sufficient room was left between these walls for sinking a line of timber cribs, 24 feet wide, placed so as to have their upper edges in line with the centre core-wall subsequently built. The bed-rock was cleaned off to receive the cribs by divers, who adjusted the cribs to their correct position. After the cribs had been loaded with stones, double 2-inch sheet-piling was laid against the upper face of the cribs and spiked thereto, the bottom of the sheet-piling being placed in a shallow trench blasted out in the rock under water. Concrete in bags was placed against the bottom of the piling so as to form a wall, about 6-8 feet wide at the base and 4 feet high. It took two divers two months to place this concrete. After a tight core had thus been constructed in the rock-fill the hydraulic filling was begun. The earth required was dumped from wagons into a receiving-box at the end of a flume on the north side of the river, and sluiced by water pumped from the river to the dam. A centrifugal pump, having a capacity of about 1 cubic foot per second, was used for the purpose. The filling was done from the core-wall towards the up-stream toe. The material assumed the flat slope of 6 or 7 to 1 under the water-line. Some bad leaks occurred through the core-wall, possibly on account of the settling of the cribs, and caused considerable loss of material. The leaks were stopped with difficulty with fine gravel brought in a barge from a few miles above the dam. Serious trouble was encountered in making the hydraulic fill on account of the necessity of doing part of this work in winter. The earth would freeze in cold weather in layers and afterwards thaw out, causing a settling of the embankment. Since the repairs have been made the dam appears perfectly tight. Dam for the Waialua Sugar Plantation.—This dam was built in 1904-1906, on the island of Oahu, 22 miles from Honolulu. James D. Schuyler, M. Am. Soc. C. E., was engaged in 1903 as Consulting Engineer on the proposed dam, and recommended that it be made a combina- tion of rock-fill and earth-fill, with an extreme height of 98 feet and a crest width of 25 feet, ro feet above the level of the spillway. A wooden core-wall was built in the rock-fill with its bottom embedded in a concrete wall, and the earth was to be sluiced into position against the core-wall, so as to have a slope of 4 to 1 on the water side. The dam was built practically according to these recommendations, under the direction of Mr. H. Clay Kellogg of Santa Anna, California. The dam has a length on top of 460 feet, a top-width of 25 feet, and a width of 580 feet at 260 DESIGN AND CONSTRUCTION OF DAMS. the base. The rock-fill is 11.5 feet wide at the top and 80 feet at the base. It contains 26,000 cubic yards of loose rock, a considerable portion of which was laid by hand as a dry wall. The outer slope of the rock-fill is ? to 1, and the inner side is vertical. The wooden core-wall was built in the rock-fill, 2 feet down-stream from its vertical face. It consists of double 2-inch redwood plank, laid horizontally, with a double layer of burlap dipped in hot asphaltum between the two layers of plank, and spiked to 3x 6” uprights, placed 2 feet apart, centre to centre. The bottom of the core-wall was embedded in a concrete wall built in a trench, which had a maximum depth of 38 feet below the surface and extended laterally into the hillsides from 14 to 28 feet. The trench was made 5 feet wide at the bottom, and was filled with concrete to a level slightly above the natural surface. The rock (basaltic boulders) was brought in cars to the site of the dam and dumped from a high trestle. The water required for making the hydraulic fill was delivered by pipes from an upper ditch to a point 2,000 feet distant from, and 50 feet higher than, the dam. Ground-sluicing was resorted to, as the available head was not sufficient for excavating and disintegrating the material. Between the point where the water was delivered and the dam there was a large quantity of earth of great depth that was considered suitable for making the hydraulic fill. For a depth of 2 or 3 feet it con- sisted of reddish-brown soil, under which there was a bright-red tufa for a depth of 20 to 50 feet, and then yellow tufa for 50 to 100 feet more. This tufa resisted the erosive action of the water in a remarkable manner. It had no tendency to slide, and would stand vertically in trenches for along time. It was found to be very difficult to sluice the tufa, as it contained no sand or grit to do the cutting and would settle in the pond very rapidly. The method resorted to for sluicing this material was to dig a ditch, about 4 feet deep at its upper end and 12 to 16 feet deep at the dam. Its length was about 1,300 feet. The earth on either side of this ditch, for a width of 12 feet, was loosened by a steam-plow and dumped by scrapers into the running water in the ditch, which had sufficient velocity to carry the earth to the dam. This was found to be the only practical way of handling the tufa, as the water had no effect when turned upon the plowed ground, and ran over it perfectly clear. The process described above was continued until the ditch grade was reached, when a new strip would be plowed and the ditch would be shifted over to the bluff-bank on either side of its original position. The total cost of placing the earth in the dam, by the method described above, amounted to 11 cents per cubic yard. The hydraulic fill has a volume of 141,000 cubic yards. It is reported to be very hard and perfectly water-tight. The reservoir formed by the dam stores 2,500,000,000 gallons. The Zuni River Dam is being built by the United States Indian Bureau to store water for irrigating the lands of the Zufii Indian Reservation in McKinley County, New Mexico, about 4o miles south of Gallup. The dam is being constructed under the direction of J. B. Harper, M. Am. Soc. C. E., James D. Schuyler, M. Am. Soc. C. E., being engaged as Consulting Engineer.* The dam, which will be gor feet long on top and 7o feet high, is being built of a loose rock embankment, backed by an earth-fill, placed by the hydraulic method. The rock-fill consists of stones, weighing 2 to 6 tons and occasionally 8 to 1o tons, laid by hand, the spaces between these stones being carefully filled with small stone. Fig. 58 shows a cross-section of the dam. No wooden core-wall was built in this dam, the liquid earth being retained by two levees of dry * The views of this dam, given on Plate X, and the dimensions were kindly furnished to the author by J.B Harper, M. Am. Soc. C. E. PLATE Y. Fic. 2.—Down-stream Face of Rock-fill. Fig. 4—Monitor Cutting Bank. ZUNI RIVER ROCK-FILL DAM, NEW MENICO. DAMS MADE BY THE HYDRAULIC PROCESS. 263 earth, about 10 feet wide, one placed against the rock-fill and the other at the outer slope of the earth-fill, The levees were made of earth hauled by teams. The water required for sluicing was delivered through an 8-inch pipe to a hydraulic giant by a steam-pump having a capacity of about 3 cubic feet per second. The pressure was sufficient to enable the X4-inch argle-bars, placed 15 feet from center to center. The 5-inch leg of each pair of angle-bars forms a joint projecting into the reservoir. The angle-bars are riveted together at their outer extremities, an iron filler 3x2 inches beirg placed between them. The expansion of the steel facing is taken up by the bending and spring of these legs, the distance between the plate and the filler being about 4 inches. The plates are riveted and calked as thoroughly as in boiler work. The bottom- and end-plates are embedded in concrete which is laid in a trench cut in the bed-rock. A pair of 5xX8-inch angle-bars is riveted at the base and another pair is placed a foot higher. Concrete is laid around these angle-irons and acts both as a sup- port for the entire steel face and is cut off for water. The ends are arrarged in a similar manner except that the angle-bars are placed vertically. Next to the facing fine stone and sedimentary material are filled in for a space of 4 to 6 inches, enough water being used to pack the filling thoroughly. Next to this comes loose rock-fill. At the dirt filling the stones were laid by hand, but others are dumped in, enough small pieces beirg used to fill the spaces between the larger stones. A spillway, 50 feet wide, cut through the rock foundation, is provided at the west end of the dam. The concrete floor of the spillway is 3 feet below the crest of rock-fill. By means of flashboards the spillway can be raised to the crest of the dam. The water is drawn from the reservoir by means of a 30-inch wooden-stave pipe which passes through the dam and extends 240 feet into the reservoir. This pipe is enclosed by concrete where it passes through the dam and it is supported in the reservoir by a rock wall to which it is anchored by steel cables. The dam and reservoir were constructed in. 1900-01 by the Pike’s Peak Power Company of Victor, Colorado, under the direction of their engineer and superintendent, Mr. R. M. Jones. 280 DESIGN AND CONSTRUCTION OF DAMS. CHAPTER IV. TIMBER DAMS, General Requirements.—Dams of brushwood, logs, cribwork, or framed timber are often built across streams to obtain water-power, to secure sufficient depth for slack-water navigation, or to divert water for irrigation. These dams are usually made strong enough to pass the streams over their crests in times of flood. They must also be able to withstand shocks from floating bodies such as ice, etc. This last requirement determines the form of the up-stream side of the dam, which should be an inclined plane (Fig. 66), in order to facil- itate the passage of floating bodies and to protect the dam against shocks. Dams have been built according to this simple profile, but unless the height of the dam be very inconsiderable the falling water will gradually undermine the dam in front, even if the bed of the river be rock and a pool of water protect it. Trautwine* states that at the Jones’s Dam on Cape Fear River, which had a height of 16 feet, the water falling vertically over the dam, usually from a height of 10 feet, into a pool of water 6 feet deep, wore out the soft shale rock (in vertical strata) on which the dam was founded for 16 feet, and under- mined the dam in a few years to such an extent that it fell into the cavity. o Fic, €6, Fic. 67, Fic. 68. He mentions another case, where water falling vertically from a dam 36 feet high into a pool of water only 2 feet deep wore out the hard slate rock in the river Io to 20 feet in twenty years, the erosive action extending from the face of the dam for a distance of from 70 to 8o feet. The Holyoke Dam (page 290) is another example of the undermining of a dam by the erosive action of water flowing over it. There are two ways of breaking the fall of the water flowing over the dam: ist. By giving the down-stream side of the dam a slope (Fig. 67). 2d. By forming this face by a number of steps (Fig. 68). The latter plan is the better of the two, as the velocity of the water flowing down an incline plane is accelerated. Whichever of the types shown in Figs. 66, 67, and 68 be adopted, an apron should be constructed in front of the dam to protect the river-bed against the erosive action of the overflowing water. The apron may consist simply of a Jayer of large stones and boulders. If the river be liable to severe freshets, the stones forming the apron must be kept in place by building a crib-dam or driving piles on the down-stream side of the layer. The whole * Civil Engineers’ Pocket Book, by John C. Trautwine. TIMBER DAMS. 281 apron may consist of crib-work filled with dry stones. Very frequently it is formed of a course of heavy timbers (10-14 inches thick) placed closely together. The distance to which the apron should extend down-stream depends upon the height of the dam and the greatest depth of the sheet of water that may pass over it. Under ordinary circumstances the length of the apron, measured down-stream, should be about twice the height of the vertical fall of the water. For dams founded on rock the apron is sometimes omitted, but this should only be done under the most favorable circumstances, viz., with hard rock covered by a pool of water having sufficient depth. Timber dams may be built, in plan, either straight or curved so as to be convex up- stream. When a straight plan is adopted the axis of the dam may either be at right angles or oblique to the current. The latter plan is sometimes adopted with a view of obtaining a longer crest for the dam, but it has the disadvantage of tending to force the current towards the bank of the river on which the upper end of the dam abuts. Instead of curving the plan of the dam, it may be pointed up-stream, especially in the case of a narrow river. Leakage may occur through the dam, around its ends, or under it. The up-stream face should be made as water-tight as possible. Some leakage will occur when the dam has just been completed. The silt and mud borne by the stream will soon diminish this loss. While it is important to prevent the water from leaking through the dam, it is rather an advantage, after the water has passed the crest of the dam, to have enough leakage take place to keep the timbers forming the structure always wet. For this purpose the planks which are used to cover the top and down-stream slope are often placed a little distance apart. Leakage around the end of the dam is to be prevented by carrying the ends into the banks and building against them substantial abutments which should be raised to a height which will prevent their being overflowed. For an important dam the abutments should be built of solid masonry. A cheaper construction consists in forming the abutments of crib- work filled with stones or simply of sheet-piling. The most dangerous leakage is that which may occur under the dam, as it would under- mine the structure. The surest method of preventing this leakage is to give the dam consid- erable width up and down stream. Asa general rule a timber dam should be wider than high. The greater the width can be made the better it will be. In a river having a soft bottom one or two rows of sheet-piles (2-4 inches thick) should be driven at the up-stream toe of the dam. It is sometimes advisable to drive sheet-piles, also, at the down-stream end of the apron. Having considered the general requirements which a timber dam built across a stream should fulfil, we will next consider the different manners in which wood can be used in the construction of a dam.* Brushwood Dams.—TIn the case of a sluggish stream, having a soft bottom, a sub- stantial dam can be formed of alternate courses of brushwood and gravel. Wood of all sizes, including saplings and even trees, should be used, the latter being always placed with their branches up-stream. After a course of brushwood 3 to 5 feet thick has been placed in position it is sunk by filling stone and gravelly earth upon it. Clay should be used but sparingly and with other earth, as it is apt to wash away. * The descriptions of the simple types of dams given on pages 282 to 288 have been taken principally ¢rom Leffel’s Construction of Mill-Dams. 282 DESIGN AND CONSTRUCTION OF DAMS. The dam is carried up by alternate courses of wood and gravel so as to have a trap- ezoidal cross-section. It is finished by facing the slopes with planking, fascines, or a covering of riprap. Log-dams.—Where timber can be obtained cheaply an excellent dam can be built, at a very moderate cost, of logs and brush, as shown in Fig. 69. The logs should be 8 to 12 inches in diameter at the butt end. The branches should be cut off the two sides of each log, which will be its top and bottom when placed in the dam. All the logs are placed with their tops up-stream. The largest logs are laid side by side across the stream to form the foundation course. The second and third courses of logs are stepped up-stream respectively about 25 Fic. 69. and 20 feet. The fourth course is stepped back about 5 feet from the third course, and the dam proper is then carried up with logs, so as to have its down-stream face almost vertical. Saplings, brush, stone, and earth are placed between the succeeding courses of logs to make the dam as tight as possible. Binders, 3 to 4 inches in diameter, should be placed across the logs of all the courses of the dam proper, and should be fastened by treenails or spikes to the logs. The top course should have several binders and should be covered with stone and earth so as to have a uniform slope. A log-dam is especially suited for soft or sandy river bottoms. Owing to its great width and ample apron it will not be undermined. It will pass severe floods without damage, as the logs, brush, and filling are strongly interlocked. Experience shows that such a dam may settle one or two feet during the first year, but after that period the settling will be but trifling. The log-dam may be straight or curved in plan according to circumstances. If much water flows in the stream while the dam is being built, the foundation courses of logs will have to be sunk by loading them with stone. An opening will also have to be left in the dam to pass the stream during the construction. It must finally be closed by building the dam at this place as rapidly and strongly as possible. In the case of a narrow stream (about 40 to 60 feet wide) a strong dam can be built of logs by adopting the pointed plan. The butts of the logs are placed against the banks and the points are notched where they cross each other. There are only two logs in each course —one from each bank. The logs must be fastened together with treenails or drift-bolts. The dam is like a roof placed on end. Its strength depends evidently upon an unyielding bearing or skew-back being provided for the butt ends of the logs. If the banks of the stream be rocky, a good bearing is obtained by trimming the rock to the required surface. When the banks consist of gravel or earth, timber-cribs filled with stone may be placed in the TIMBER DAMS. 283 banks to form the skew-backs for the logs. In the latter case the logs forming the dam should extend into the crib, being notched and spiked to its timbers. Water-tightness is obtained by filling in a slope of gravel on the up-stream side of the dam. An apron of logs placed closely together, having their top and bottom sides squared, should be constructed on the down-stream side. Dams I0 to 15 feet in height have been built according to the simple plan just de- scribed, and have stood successfully for many years. Crib-dams.—A more economical plan of using logs to form a dam than the plan shown in Fig. 69 consists in building cribs with the logs and filling the spaces between them—ordinarily 6 by 6 feet to 10 by 10 feet—with stone or gravel. Fig. 70 shows a crib- Fic 70. dam which has a triangular profile like the log-dam. The foundation course is formed of large logs, placed at right angles to the stream, and carried into the bank on both sides. These logs, which are generally placed 6 to 8 feet apart, are laid in trenches excavated to such a depth that the tops of the logs project just above the river-bed. If the width of the stream be considerable, two or more logs spliced together will be required for each of these trenches. The second course of logs is laid at right angles to the foundation course. The apron is formed between the two foundation-logs which are furthest down- stream by placing planks between the logs of the second course. These planks should project under the third course of logs, with which the dam proper begins. Each course of logs is placed at right angles to the one below it. ‘The logs are not notched where they cross each other, but simply flattened so as to form good bearings. They are spiked together by iron drift-bolts (usually # by # in.) at each intersection of logs. Wooden tree- nails of hard wood may be used instead of the spikes. The top cross-logs should be securely fastened by iron bolts passing through two or three logs beneath. In building cribs the timbers should be so placed that the pockets of the crib will have vertical sides. Formerly the timbers were often staggered so as not to be directly over those below, but nothing is gained by adopting this plan. In the dam shown in Fig. 28 the triangular section is obtained by making the logs across the river smaller at the up-stream than at the down-stream side of the crib. The down-stream face of the dam is made almost vertical. A course of planks (about 4 inches thick and 12 feet long) securely spiked to the logs is placed on the up-stream side of the crest of the dam. This course is continued up-stream by a slope of gravel or earth. Crib-dams can be used in almost any kind of river bottom. If placed on rock the bottom logs should be fastened to the foundation by iron bolts. For this purpose holes are drilled in the rock. The lower end of each iron anchor-bolt is split from 5 to 6 inches. 284 DESIGN AND CONSTR CTION OF DAMS. By placing a wedge in the split end of the bolt and driving the latter down into the drill- hole, the bottom of the bolt is expanded and anchors the log firmly to the rock. Unless the dam is to have but little height, it will be found most convenient to form it of square cribs, placing a low crib in front of the main dam to form the apron, and a slope of gravel and earth on the up-stream side. This plan is the method usually adopted. Descriptions of some dams of this kind which have been constructed and which have stood successfully for many years are given on pages 145 to 147. Pile-dams.—If the river bottom is soft, but does not contain quicksand, a substantial dam can be built by driving one to three rows of piles across the river, the piles in each row being driven as closely together as possible. Logs and brushwood are placed hori- zontally between or against the piles, according to circumstances. In Fig. 71 two rows of Fie. 71. piles are shown, the horizontal logs and brush being placed between them. An apron is placed in front of the dam, and long piles are laid about Io feet apart, as ties from the piling into the earth filling. Plank-dams.—A strong dam can be formed by laying planks so as to form a vertical arch, convex up-stream. Planks Io to 12 inches wide and 2 to 24% inches thick may be used for this purpose. They should not be more than 12 feet long, so as to form short chords of the arch. If the dam be founded on hard rock no apron is required. A level bed must be prepared for the first course. Concrete or rubble masonry may be used to level the irregularities of the rock. At both ends of the dam skew-backs must be cut for the arch to bear against. Having laid the first three or four courses of planks, they should be anchored to the rock by iron split bolts in the manner described on page 140. The heads of the bolts must be countersunk in the top plank. The other courses of planks are merely spiked or fastened by treenails to those beneath them. The joints between the planks should be cut on radial lines and closely fitted. With this dam, too, it is advisable to place a slope of earth and gravel on its up-stream side. If a dam is to be built of planks on a soft or sandy river-bed an apron must be provided. A foundation is prepared for the dam by laying long, square timbers about 10 by 12 inches in section, or logs squared roughly to this size, either closely together or 2 or 3 feet apart according to the softness of the bottom and the height of the dam. The down-stream part of these timbers forms the apron, if they are placed closely together. If they be two or three feet apart planks are spiked to them to form the apron. Instead of building a single arch of planks, as described above, a double arch may be built as shown in Fig. 30, the space between the arches being filled TIMBER DAMS. 285 with earth, gravel, and stone. Such a dam would of course be stronger than the single- arch dam described above. As the dam shown in Fig. 72 is supposed to be built in soft ground, strong abut- ments must be constructed to resist the thrust of the arches. Cribs made of planks i Zan SSS Ue i Ss ella (ll ILL TE Dey) PA _ BA ee WE OSES 5 TES TES - => — Mae a Z Up De ZL Pe EET T Z GaN = iT S BO EE: LE aS Z GEL E Ae WA Fic. 72. and filled with stone will answer for this purpose. Where the arches abut against the cribs the alternate courses of planks in the arches should be extended into the plank-cribs in order to tie the work well together. A third plan of building a dam of planks is shown in Fig. 31. In this case the planks form a series of steps on either face, except at the lower part of the up-stream face, where they are laid as a vertical wall. Each course is securely tied by laying planks about 8 to 10 feet apart, at right angles across the dam, as shown in Fig. 73. The Fic. 73. space between the planks is packed with earth and gravel and a slope of earth is placed on the up-stream side. The planks used should be 10 to 12 inches wide and 2 to 3 inches thick. They may be spiked together, But it is preferable to fasten them together by wooden pins. These pins are usually made square to avoid splitting the planks in driving the pins. For soft-wood planks pins # by # inch are driven into round holes # inch in diameter. If the wood be hard the holes must be made somewhat larger. The planks on the down-stream side should be of oak. On the up-stream side planks of sycamore, elm, etc., may be used below the water, but above it the planks should be of oak. If a dam of the kind just described is to be placed on a soft bottom, a founda- tion of logs or square timber must first be laid, as already explained. 286 DESIGN AND CONSTRUCTION OF DAMS. Framed Timber Dams are made in various ways, according to circumstances. On a rock bottom a dam of moderate height can be built like a tight board fence. For a dam 6 feet high, posts 16 inches square are placed about 12 feet from centre to centre, the foot of each post being put in a hole about two feet deep excavated in the rock. Each post is supported on the down-stream side by an inclined brace 12 inches square. One end of the brace is let about a foot into the rock and bears against a piece of 2-inch planking. The other end bears against a shoulder cut in the post. A thin key serves to wedge the brace and post firmly together. Three horizontal timbers, about 6 by 10 inches, are placed in notches cut in the posts, on their up-stream side. One of these timbers is securely spiked at the bottom, one at the middle, and the other at the top of the post. Vertical pieces of 2-inch plank are nailed to the horizontal timbers. If well-seasoned plank be used, they should be spaced a trifle apart, as they will swell when they become wet. If the planks are green they will shrink when wet, leaving thus cracks between them. The difficulty of the swelling or shrinking of the planking may be overcome by placing alternately well-seasoned and green planks. The top of each post should be levelled in the down-stream direction, to let water run freely off the post. The holes in which the posts are set should be cut in a dove- tailed fashion, the dovetail being on the up-stream side. The end of each post is cut to fit the dovetail, a shoulder 2 inches deep being made on that side. The hole cut in the rock must be larger, of course, than the foot of the post. In order to secure the post firmly in the hole, a long, wide key, about 24 inches thick, is placed on its lower side. It is important that this key should be well-fitted to the hole and that it be placed on the lower side of the post so that the pressure against the dam forces the key and post together. If the dovetail of the hole and the key are placed on the up-stream side of the post, the water-pressure wil! tend to force them apart. To insure water-tightness and to prevent shocks from floating bodies it is advis- able (but not absolutely necessary) to place 4 siope of earth and gravel against the up-stream side of the timber-dam. No apron is provided in this case, as the dam is supposed to be erected on a bed of hard rock. Should the rock be soft it must be protected by an apron. Fig. 74 shows a simple kind of hollow frame dam. It can be used for any kind of a foundation, and requires much less timber than a dam made of logs. In Fig. 74 the dam is supposed to be built on a rock foundation. Short sills 10’ % 10” & 4’ are securely bedded parallel with the current and 8 feet apart, centre to centre, in both TIMBER DAMS. 287 directions. On these be -blocks the cross-sills of 12 by 12 inch timber are laid. Where joints occur on these sills 2-foot splices should be made, a block of wood being put under each joint. The cross-sills should be anchored to the rock by split-bolts 14 to 1% inches in diameter, which should pass through the cross-sills, bed-block, and about 34 feet into the rock. For the down-stream sill bolts should be placed 8 feet apart, but for the up-stream sill a bolt should be put in every 4 feet, a block being put under the cross-sill at every point where an anchor-bolt is placed. The cross-sills support the bents, framed of 10’ X 10” timber, which are placed 8 feet apart. Cross-ties of 4” x7” timber are fastened about 4 feet apart to the caps of the bents. The dam is completed by spiking 14 to 2 inch planks to the cross- ties. It is not advisable to use planks of much more thickness, as they are more apt to rot on account of the wood being wet on one side and dry on the other. The remarks made on page 286 about the spacing of the planks apply, of course, also to this case. Fig. 75 shows another manner of framing the bents of a timber-dam. When it is necessary to break the force of the water the down-stream face of the dam can be Fic, 75. formed of a series of steps or an incline, as explained on page 280. A dam built at New Hartford, Conn., is a very good example of the latter style of construction. We shall describe it somewhat in detail to illustrate fully the construction of timber-dams. The Dam at New Hartford, Conn., was built in 1847 across the Farmington River for the Greenwoods Company. At the place where the dam was constructed the river bottom consists of cobble-stones, gravel, and quicksand. The banks are composed of gravel and sand. The dam has a length of 232 feet on its crest. It was originally built 21 feet high, according to the trapezoidal profile shown in Fig. 67, the width at the bottom being 68 feet. Both faces of the dam make an angle of 27° with a horizontal plane. The timbers of which the dam is built are 9 to 12 inches thick. The courses of timbers were laid alternately crosswise and lengthwise of the stream, the first course being laid across the stream. The timbers parallel with the current are 6 feet apart, those at right angles to the stream are 2 to 3 feet apart. Where the timbers cross each other they were fastened. 288 DESIGN AND CONSTRUCTION OF DAMS. with 2-inch round spikes, 20 inches long. Both faces of the dam were originally cov- ered with 3-inch oak and chestnut planks, placed close together and fastened with 7-inch cut spikes. All the spaces between the timbers were filled with stone. The crest of the dam was formed by a strong cap-log. The apron extends 14 feet in front of the dam. It consists of timbers 12 inches thick placed close together. The mudsill supporting the down-stream end of the apron timbers is supported by piles driven about 15 feet into the river bottom. The apron was well tied to the dam by using, every 6 feet, long timbers extending 25 to 30 feet into the dam. The other apron timbers run only 2 or 3 feet into the dam. Sheet piles were driven at the up-stream toe of the dam. A slope of gravel, reaching within 4 or 5 feet of the cap- log was filled in on the up-stream face. Substantial masonry abutments were built on pile foundations on both sides of the dam. During freshets 6 feet of water frequently passes over this dam and as much as 10 feet has been recorded. As the apron of the dam did not extend far enough, the water washed out a considerable quantity of gravel in front of it, and the proprietors were obliged to build cribs of logs, filled with large stones weighing 2 or 3 tons, to protect the dam against being undermined. These cribs were chained to the piles supporting the apron. After the dam had been standing about twenty years the upper 10 feet had to be renewed, as the timbers had become rotten. This was supposed to have been caused by the hot vapor forming in summer inside of the dam, which faces south. The planking was therefore removed from the down-stream slope of the dam to allow the vapor to escape. Dams across the Schuylkill River.*—On Plate XCVI. we show sections of a number of timber-dams which have been constructed across the Schuylkill River, to obtain slack-water navigation. No. 1 was built in 1819 at Plymouth. It was constructed without a coffer- dam on a bed of rock. The bottom timbers (12 X 16 inches) were placed 8 feet apart, par- allel with the stream and secured to the rock bottom by two-inch oak treenails. The other courses of timbers were laid alternately crosswise and lengthwise of the stream, the timbers being securely fastened together with treenails, no iron bolts being used in the dam. The up-stream face of the dam was covered with timbers 10 inches thick placed close together. Until this sheathing was laid the water could pass freely between the timbers, as no stone filling was placed inthe dam. The covering was done from both ends until only 60 feet of the dam was left uncovered for the water to pass through. The remaining sheathing was carefully cut and fitted and placed quickly in the dam by a large force of men before the river could rise so as to interfere with the work. A slope of clay and stone was placed against the up-stream face. This dam stood for thirty-nine years, withstanding successfully floods that rose to a height of 11 feet above its crest. Although it was built upon a tolerably firm micaceous rock in nearly vertical strata, covered ordinarily by about 2 feet of water, the rock in front of the dam was worn out in thirty-nine years to an average depth of 3 feet (nearly an inch per year).+ The depth of the water on the crest was usually 6 to 18 inches deep. The structure was replaced in 1858 by the dam shown in sketch No. 3. * The facts stated about these dams and Plate XCVI. are taken from a paper on ‘‘Dam Building in Navigable and other Streams,” by Edwin F. Smith, published in the Proceedings of the Engineers’ Club ot Philadelphia, for August, 1888. ¢ The Civil Engineers’ Pocket Book, by John C. Trautwine, page 382. TIMBER DAMS. 284 The dam shown in sketch No. 2 was built in 1836. It was filled with stone and protected against leakage by sheet-piling. The framing in this dam was rather expensive, as the timbers had to be accurately fitted and joined. In 1846 the dam was raised for an enlarged navigation. It is still in an excellent state of preservation and has required but little repairs. Sketches 3, 4, 5,,and 6 show dams of more recent construction. They illustrate the type of dam now adopted for the Schuylkill Navigation. One of their characteristic features is that the up-stream face is made vertical or almost so. Experience has shown this type of dam to be cheaper, heavier, and stronger than the earlier kinds of dam built across the Schuylkill. It was urged against this type that the wide crest or comb would be damaged by debris or ice in floods, but long experience has proved that dams built accord- ing to this style are injured less than those having narrow crests. Sketch No. 5 shows the Felix Dam which was built in 1855, 6 miles above Reading, Pa. It is 19 feet high and 27 feet wide at the base. It is similar in construction to No. 4.. Although it has been subjected to heavy ice-floods, it is still in a remarkably good state of preservation. Sketch No. 6 shows the Kernsville Dam, which was built on a gravel bottom in a gap of the Blue Mountains. It required a heavy apron to protect it from being undermined. In this case the apron was formed by extending the foundation-cribs of the main dam. This is not generally considered to be good practice on account of the injurious effect that may be produced on the main dam by the concussion of the overflowing water. In this particular case no harmful effect was apprehended, as the fall of the water was insignificant. The Columbia Dam (Sketch No. 7) was built in 1875 across the Susquehanna River at Columbia, Pennsylvania. It is 6,847 feet long. Its average height is only 74 feet above low water. The base was made 30 feet wide to give the dam sufficient weight and strength to resist the violent floods to which it is exposed. The crest of the dam is 16 feet wide and level. The up-stream slope is vertical; the down-stream slope has a fall of 21 inches in 134 feet. The principal longitudinal timbers at the crest are of 12 by 13 inch white oak, in lengths of 40 to 50 feet. A covering of 5-inch white oak plank is placed over the crest and down-stream slope, and securely fastened with #-inch bolts 124 inches long. The planks in the down-stream slope are placed 4 inch apart, to permit the water to keep the timbers wet. On the up-stream face sheet-piling of 4-inch white pine planks, carefully jointed, was driven to the rock. This face of the dam is protected by plates of 74-inch iron, reaching well over the crest timbers and down upon the sheeting. The structure described replaced an older dam built with a narrow crest and a long down-stream slope, as it was supposed that the ice would pass freely over it. Experience proved this not to be the case. The Susquehanna River is noted for its great ice-freshets. In 1857, 4219 lineal feet of the dam was destroyed by ice; in 1865, 2500 feet; in 1873, 946 feet; and in 1875, 1085 feet. In the last mentioned year 2649 additional feet of the dam was damaged by the carrying away of the down-stream slope. On account of these experiences the dam built in 1875 (Sketch No. 7) was made with a wide crest like those adopted on the Schuylkill, and the results have proved to be very satisfactory. 290 DESIGN AND CONSTRUCTION OF DAMS. This dam has withstood some of the severest ice-floods ever known on the Susquehanna. In thirteen years the level crest suffered very little, but the 5-inch oak planking on the down-stream slope, while almost uninjured at its junction with the crest, was worn down to I or 2 inches thickness at the point of the overfall, leaving the iron bolts by which it was fastened projecting 3 to 4 inches and bent over down-stream. If the dam had to be rebuilt, the down-stream slope would probably be abandoned, a level deck being adopted for the whole width of the dam. In building dams in rivers subject to destructive ice-floods, a timber dam should be made as heavy as possible. This object will be best accomplished for low dams by adopting a square cross-section and placing a slope of stone and gravel to help the ice over the dam. The upper part of this slope should be protected by a paving of stone. It is not advisable to use much timber in such a dam, as it reduces the weight of the structure. In the winter of 1887-88 two short sections of the Columbia Dam, 50 to 60 feet in length, raised 12 to 18 inches. This was ascribed to the preponderance of white-pine timber used in the dam at these points. When these sections raised the dam was submerged in 10 feet of backwater caused by an ice-pack some miles below. The Holyoke Dam™* (Plate CXVII.) was built in 1849 across the Connecticut River by the Hadley Falls Company (now the Holyoke Water-Power Co.). Before this struc- ture was begun a temporary dam was built a little further up-stream to serve as a pro- tection during the construction of the permanent dam and to furnish water-power in the meantime. The temporary dam was built somewhat like the permanent dam, con- structed subsequently, but was given less strength. The gates of the temporary dam were closed on November 16, 1848. When the water reached within 2 or 3 feet of the top, the whole dam, except 75 feet on one end and 150 feet on the other, was rolled over and floated down-stream on the crest of a wave about 8 feet high. The loss to the company on account of this failure is stated to have been $40,000 to $50,000. The permanent dam shown in Fig. 1, Plate CX VII., was begun the following year and finisned in the summer. This dam is still standing, but will soon be replaced by a masonry dam below it. It is 1017 feet long and has a maximum height of about 30 feet. The down-stream face of the dam was originally made vertical, but in 1870 a sloping apron was built in front of the dam, as shown in Plate CXVII. The dam was founded on a ledge of red slate and sandstone, which dips down-stream about 30° from a horizontal plane. The whole dam was built of heavy timbers, nothing less than 12 by 12 inches being used. The bottom timbers (1§ by 15 inches in section) were placed parallel with the current and were bolted to the bed-rock with iron bolts 1} inches in diameter, about 3000 of these bolts being used in the dam. The bottom timbers and those directly over them were placed 6 feet apart and divided the dam into 170 sections. The up-stream slope, which makes an angle of 20° 45’ with a horizontal plane, was covered with three courses of 6-inch timber. This planking was strongly fast- ened together with spikes and treenails. The rolling top or combing was covered across the whole length of the dam with sheets of boiler-iron. Four million feet, board measure, of wood was placed in the dam. As the dam was built up the pockets between the timbers were filled with stone to a * Paper by Clemens Herschel, Trans. Am. Soc. C. E., for 1886, and Engineering News of May 13, 1897. TIMBER DAMS. 2gt height of 10 feet. Above this the dam was originally left hollow. The foot of the dam was protected by concrete. A bank of gravel was filled in against the up-stream face of the dam, beginning 70 feet above the dam and covering over 30 feet of the slope. Strong abutments of masonry were built on both sides of the timber dam. The total cost of the dam amounted to $150,000. During the construction of the dam the river-water was passed through 46 gates, each having an opening of 16 by 18 feet. These gates were closed for the first time on October 22, 1849, the water being thus forced to pass over the dam. The work stood this test very successfully. The leakage through the dam was very trifling, not more than was thought necessary to keep the timbers from decay. In November, 1849, 6 feet of water passed over the top of the dam. It caused the windows in Springfield, 8 miles away, to rattle, as no provision had been made to allow the air to pass freely from abutment to abutment under the sheet of water. In April, 1862, 124 feet of water passed over the dam, which is the maximum height the water has reached. The water, ice, logs, etc., passing over it rapidly wore away the rock in front of it. By 1868 the ledge had been eroded to a depth of 20 to 25 feet, and the dam had become undermined in some places. Besides the wearing out of the rock, the front timbers had become injured by logs and ice which, after passing over the dam, were forced against the front face by the eddies caused by the falling water. In some cases logs having become wedged among the front timbers and being struck by the falling water forced the timbers apart, acting like large levers. In order to protect the dam against such injuries and to reduce the fall of the water, a large inclined apron of cribwork was built in front of the dam during the years 1868, 1869, and 1870 Plate CXVII.). This crib, which exceeds the original dam in volume, was built of round logs laid so as to form pockets 6 by 6 feet, which were filled with stone to the top before the covering, consisting of 6-inch planks of hard wood, was put on. The cost of the apron is given variously as $263,000 to $350,000—about double the cost of the original dam. The construction of the apron merely transferred the erosive action of the water further down-stream. The slope of the apron being nearly parallel with the dip of the rock, the circumstances for washing out the ledge were very favorable. By 1886 the rock in front of the apron had been eroded in places to a depth of 20 to 25 feet. While the apron was being constructed a considerable amount of stone was also filled into the old dam. This work was done carelessly, stones weighing 4 to 5 tons and even whole scow-loads of stone being occasionally dropped on the up-stream slope of the dam. The leakage through the dam, which in after years entailed much expense, was probably partly due to the injuries thus sustained. From 1849 to 1879 only trifling repairs were required on the dam with the excep- tion of the construction of the apron. In the latter year a break occurred in the plank covering of the up-stream slope. Many similar breaks taking place in the next few years, the whole up-stream slope was replanked in 1885. At the same time sheet-piling was driven longitudinally through the dam, about three bents back from the face, and gravel dumped and puddled on both sides of the sheet-piling. The cause of the breaks was the rotting of the planking (which, as already stated, had been injured by stones being 292 DESIGN AND CONSTRUCTION OF DAMS. dropped on it) and also of some of the timbers. For a full account of how the dam was repaired we must refer the reader to Mr. Clemens Herschel’s Paper (Trans. Am. soc, G, E., for 1886), As the repairs appeared to have no permanent effect in stopping the leakage, it was finally decided to build a masonry dam 112 feet at one end and 132 feet at the other down- stream from the old timber structure. Surveys for the new dam were made in 1891. The construction was begun in 1895. It is expected that the dam will be completed during the season of 1899. Figs. 2 and 3, Plate XCVII., show the profile adopted for the masonry dam. The upper part of the down-stream face is the parabola, which a sheet of water 4 feet in depth over the crest would describe in falling freely. The parabola continues to the point of reversing below which a cycloid (the curve of ‘‘ quickest descent’’) is adopted for the face. At the extreme toe the face is turned somewhat upwards to break the force of the water and to prevent it from cutting the ledge beyond. The back slope forms a series of steps, 5 feet high, equivalent to a batter of 1 foot in 5 feet. The length of the rollway of the new dam will be 1020 feet. The plans for the masonry dam* were prepared by Mr. E. S. Waters, Chief Engineer of the Holyoke Water Power Company. In conclusion, it may be of interest to mention some of the lessons taught by the old timber dam and summarized by Mr. Herschel in his ‘‘ Paper”: -Ist. A wooden dam should not be left hollow, as the foul air on the inside will eventu- ally rot the timbers. A stone filling will not prevent this decay, but a tight filling of gravel will protect the timbers against rotting. 2d. A masonry shelf on a masonry abutment should not take the place of the last frame of adam. The dam will probably settle, but the masonry will not, and thus a distortion will be produced in the framing of the dam. 3d. The down-stream face of the dam should never be vertical unless the height be very insignificant. Ath. An apron should be provided and given a proper form to prevent the water from washing out the river-bed in front of it. A long, steep slope of timber on the up-stream side of a dam is very objectionable.. Mr. Edward F. Smith has pointed out that if the plan of the original Holyoke Dam had been turned around so that the up-stream face would have been downstream, and if a broad comb 10 to 15 feet wide had been added at the up-stream (vertical) face of the dam, adding about 30 per cent to the mass of timber and stone, the cost of the expensive crib-apron would have been saved.t A slope of gravel on the upstream side instead of the long timber one would have made the dam tighter and have avoided all the expensive repairs which became afterwards necessary. : The simple triangular profile shown in Fig. 66, page 280, is often adopted for low dams, but the experience with the Holyoke Dam proves clearly that such a profile should never be used for a high fall of water. * For a full account of the manner in which the masonry dam is being built, see Engineering News for May 13th, 1897. + Proceedings of Engineers’ Club of Philadelphia, for August, 1888, TIMBER DAMS. 293, The Canyon Ferry Dam was built in 1898 across the Missouri River near Helena, Mon- tana, for the Helena Water and Electric Power Company. All the plans for the work were prepared by Mr. J. T. Fanning, the Consulting Engineer of the Company. Fig. 76 shows a section of the dam which consists of timber cribs filled with stone. It is 485 feet long and 29 feet high. The timbers are fastened together with iron drift-bolts. 20 to 30 inches long. The down-stream face of the dam formed originally three steps to break the force of the water and prevent it from scouring out the river-bed. The steps were covered with 20 inches of timber (two courses 10/’12’’ timbers laid on the 12-inch side). The risers were covered with two courses of 3-inch plank, lap-jointed. The back of the dam was covered in a similar manner with 2-inch plank. An earth slope, riprapped at the wet Fic. 76.—CANYON FERRY DAM, top, was placed against the back of the dam, and below the dam large rocks were filled in to the surface of the river for a distance of 25 feet, being held in place by a row of round piles. The timber-dam was founded on a bed of gravel and granite sand, which is almost impervious to water. Both above and below the crib-dam a row of triple-lap sheet-piling made of 3 by 12 inch plank, stiffly bolted together, was driven to a depth of about 12 feet below the river-bed. Masonry abutments were built on both sides of the crib-dam to a height of 124 feet above its crest. On the east bank an earth dam 285 feet long, having a masonry core-wall and slopes of 2 to 1 and 14 to I respectively on the up-stream and down-stream sides,* was. built to the hillside, the top of the dam being at the level of the top of the abutments. * Soon after the dam had been completed, 5 feet of water passed over its crest, With this depth the sheet of water, after passing over the first step, cleared the other two and struck the apron and protection riprap with such force as to cause scouring. As a result of the undermining, part of the dam, about 200 feet long, settled and moved out of line, the maximum settling being about a foot and the maximum movement down-stream being 5 to 6 feet. The dam was repaired with new cribbing, heavily anchored and tied together. A timber apron, 49 feet long,. was placed down-stream of the dam, and two slopes of timber were substituted for the three steps, the first slope being 39 feet long and the second having a length of 60 feet. 294 DESIGN AND CONSTRUCTION OF DAMS. CHAPTER V. STEEL DAMS. Steel Dam at Ash Fork, Arizona.*—This dam is situated four miles east of Ash Fork, a station of the Santa Fé Pacific Railway (Atchison, Topeka and Santa Fé Railway system). It was constructed to form a reservoir for supplying water service for the railroad. The reservoir stores 36,000,000 gallons. It is formed in a dry canyon, known as Johnson’s Canyon, in which water flows only at two periods each year. Before the reser- voir was constructed the water required for the service of the railroad, about 90,000 gallons per day, had to be brought in tank-cars from a distance of 27 to 45 miles. The steel portion of the dam has a length of 184 feet, the total length on top of the dam, including masonry abutments, being about 300 feet. Its greatest height is 46 feet. The steel part of the dam consists of 24 triangular bents 12 to 42 feet high, which are placed 8 feet from centre tocentre on concrete foundations. The bents form with the rock bottom of the canyon right-angled triangles having their inclined sides, which are on a slope of 45°, turned up-siream. The structure is composed of alternate rigid and loose panels. The general arrangement of the panels and of the bents and details of one of the highest bents is given on Plate XCIX. Fig. 1 of Plate BB shows the construction of the dam. The up-stream inclined columns of the bents are formed of 20-inch I-beams, weighing 65 pounds per yard, which are reinforced on their under side with a plate one- half inch thick and 18 inches wide. Each vertical or inclined post is composed of 4 Z-bars and a web plate. Alternate panels of the structure have transverse diagonal bracing. The crest or apron plates, which fit the braced panels between the bents, are riveted to a curved angle which is riveted to the upper end of the curved plate, while in the unbraced panels this angle merely bears on the apron plate. This arrangement makes provision for expansion and contraction. The face of the dam is formed of steel plates, 3 inch thick and 8’ 103 wide, which are riveted to the outer flanges of the inclined I-beams of the bents. The plates are generally 8 feet long and are curved to a radius of 74 feet, so as to form a series of gullies down the face, leaving a flat part to be riveted to the I-beams. The curved plates do not, however, extend into the concrete foundations. They are replaced in the bottom course by flat plates, the bottom curved plates being dished toa radius of 3’ 84’, forming a segment of a sphere. The edges of all face plates and their splices are planed to a bevel edge for calking. * See Engineering News, May 12, 1898, and ‘Structural Steel Dams,’ by F. H. Bainbridge, in Journal of Western Society of Engineers, October 1905. PLATE BB ASH FORK STEEL DAM. REDRIDGE STEEL DAM. ST_EL DAMS. 207 A masonry abutment, with its water face on a slope of 45° projecting 6 inches beyond the steel work into the reservoir, is built at each end of the steel dam. ‘The steelwork is anchored into these abutments by two angle sheets. All the steelwork is painted with two coats of Detroit Sulphite Paint. The structure is covered on the down-stream side by corrugated iron plates to keep visitors away. No special spillway is provided, as the dam is designed as an overflow weir. Its curved crest plates project on the down-stream side. The outlet is a 6-inch pipe bedded in concrete in a trench excavated in rock, under the dam, the pipe terminating in a drain within the reservoir. From the down-stream side of this pipe a 4-inch pipe extends to Ash Fork. When the reservoir was filled the steel part was found to be perfectly water-tight, but leakage occurred where the steel plates joined the concrete at the sides and bottom of the dam. In 1900 the concrete was covered with asphalt, and the whole structure is now reported to be water-tight. The dam was designed by Mr. F. H. Bainbridge in collaboration with Mr. James Dun, Chief Engineer, and Mr. A. F. Robinson, Bridge Engineer of the Santa Fé system of rail- roads. The Redridge Dam, Michigan,* was constructed in 1901 to form a reservoir for supplying water to the stamp-mills of the Atlantic Mining Company and of the Baltic Mining Company. In this case the concrete base was made sufficiently strong to resist overturning and sliding instead of depending on anchorage to the bed-rock, as in the Ash Fork dam. The steel portion of the dam has a length on the crest of 464 feet and a maximum height including the concrete base of about 74 feet above the rock foundation. The steel bents are placed 8 feet apart. Figs. 1 and 2, Plate C, show respectively the lowest and the highest bent in the dam. Fig. 2 of Plate BB gives a view of the dam during erection. The face members of the bents consist of 15-inch I-beams for the low bents and 24-inch I-beams for the high bents. The face plates are of }-inch steel plate 16 feet long curved concave to the water to a radius of 7’ 574’’. These plates have on each side a flat strip 5% inches wide, which is riveted to the flange of the I-beam. A course of flat plates is placed below the lowest course of curved plates, the open space left between the plates being closed by an inclined diaphragm. The vertical joints are double-riveted, the face plates lapping each other on the I-beam. The rivets are 3 inch in diameter with 24-inch pitch. The ironwork is continued with %-inch plates down the vertical face of the concrete base. The face plates were given a coat of Edward Smith & Company’s durable metal coating both before and after the erection. The rest of the structure was painted with graphite paint. A special waste-weir is provided for this dam. The work was designed by J. F. Jackson, M. Am. Soc. C. E., Engineer of the Wisconsin Bridge & Iron Company. F. Foster Crowell, Mem. Am. Soc. C. E., acted as Consulting Engineer. * See Engineering News, August 15, 1901, and “Structural Steel Dams,” by F. H. Bainbridge, in Journal of Western Society of Engineers, February 1903. 298 DESIGN AND CONSTRUCTION OF DAMS. The Hauser Lake Dam (Plate C -) was recently constructed for the Helena Power & Transmission Company across the Missouri River, about 15 miles from Helena, Montana. It is built of steel, in a similar manner to the two steel dams described above, but some improve- ments were made in the details. It is 630 feet long and has an average height of about 75 feet. The up-stream slope is 14 horizontal to 1 vertical. The dam was founded partly on gravel and partly on solid rock. Friestedt steel sheet piling, 35 feet long, was driven at the up-stream toe of that part of the dam that was founded on gravel, and steel plates were connected to them. The dam was designed by J. F. Jackson, M. Am. Soc. C.E., Engineer of the Wisconsin Bridge & Iron Company, who has furnished the author with the informa’ion given above. The dam has a factor of safety of 4 against overturning and otf 2 against sliding. A waste-weir, 500 feet long, having its crest 12 feet helow the top of the dam was provided. PLATE CC. HAUSER LAKE DAM IN CONSTRUCTION. HAUSER LAKE DAM IN CONSTRUCTION. seep Thee mae PART Ill. MOVABLE DAMS, CHAPTER I. FRAME-DAMS. Canalization of Rivers.—On many rivers navigation becomes impossible at shoals during periods of low water. In early times boats had to be kept at such places until rain-storms raised the river sufficiently to carry them over the shallow points. The first improvement attempted to remedy this trouble consisted in building dams (weirs) across the river where needed to increase the depth of water for ‘‘slack-water naviga- tion.” Each of these dams had usually one or more openings, which could be tempo- rarily closed by ‘‘stanches”’ consisting of spars, planks or gates, bearing at the bottom against a sill and at the top against movable wooden beams. By removing these beams suddenly, and thus releasing the stanches, an artificial flood was produced which carried any boats that might be above the dam through the openings and over the shoals below. This process was called ‘‘ flashing,” or ‘‘flushing.”” It was in use on several rivers in France until the middle of this century and also in England on the Thames and Severn.* Instead of vertical planks, etc., for stanches, horizontal beams. (poutrelles), placed one on top of another, were sometimes used in France to close openings of 15 to 18 feet in a dam. By a suitable arrangement, these beams could be suddenly released for flashing. In order to make it possible to take a boat up or down stream without removing the stanches, a lock was often built at these dams. By constructing at suitable points dams with locks or stanches, a river was practically converted into a canal,+ with the difference, however, that it still remained subject to floods, for which pro- vision had to be made. Needle-dams.t—About the end of the eighteenth century the French Government commenced to improve internal navigation by constructing substantial ‘‘ navigable * Minutes of Proceedings Inst. C. E., Vol. IV., p. 111. +The river Lot, in France, was the first river to be canalized in this manner. Dams were built across this river in the thirteenth century and locks were introduced in the fifteenth century. ¢ The authorities on movable dams, which the writer has consulted, are given on page qt1. For the historical notes on works of this character in France, he is indebted to Lagrené’s ‘‘Cours de Naviga- tion Intérieure” and to memoirs on Movable Dams that have appeared since 1839 in the ‘‘Annales des Ponts et Chaussées.” 301 302 MOVABLE DAMS. passes,” 26 feet wide, in some of the dams built across rivers, especially on the Yonne, a branch of the Seine. These passes were built with side-walls and aprons of masonry. They were closed by small wooden spars called needles, which bore on the bottom against a masonry sill and at the top against wooden beams, pivoted on iron pins placed in the side-walls. Later on, the wicth of the passes on the river Yonne was increased to 40 feet, a cable which could be slacked or stretched as required being substituted for the pivoted beams. As a pass only 40 feet wide was found to involve considerable inconvenience and danger to navigation, M. Poirée, who had charge of the improvements on the river Yonne, increased the width of the pass at Basseville, which was constructed in 1834, to 72 feet. For such a width a cable could no longer be used for supporting the upper ends of the needles. M. Poirée substituted for the cable a series of short iron bars, which were fastened to the top of iron frames (trestle-bents), placed at short intervals across the pass, from one side-wall to the other. In the Basseville dam these frames were originally two metres (6.56 feet) apart, but this distance was afterwards reduced to one-half. In needle-dams erected subsequently the distance between the frames varies from 3 to 4 feet. One of the chief features of M. Poirée’s invention was the manner in which he removed the frames when the pass was to be opened. This was accomplished by removing the needles by hand, unhooking the bars connecting the frames, and turning the latter down on journals placed in their lower bases until they rested in a recess in the masonry apron, presenting thus no obstacle above the sill of the floor. It was objected at first that the frames would be silted up while lying thus on the apron, and that it would be very troublesome to raise them again, but experience on the Yonne and similar rivers has proved that no difficulty has been experienced in this respect, as the bents are only turned down during periods of high water, when but little silt is deposited. In Fig. 77* we show one of the earlier Poirée dams. The frames are made of bar iron about 14 inches thick. Each frame has a trapezoidal form, the top and bottom pieces being horizontal, the up-stream post vertical and the down-stream post slightly inclined. A diagonal brace serves to stiffen the frame. The ends of the lower base form journals which fit into cast-iron boxes fixed in the floor. The frames are 6.23 feet high, 2.56 feet wide on top, and 4.92 feet wide at the base. They are placed a metre (3.28 feet) apart, and weigh each 242 pounds. Wooden planks placed on top of the frames form a bridge which enables the dam-tender to replace or remove the needles, etc. Two men are able to raise or lower a frame by means of iron chains joining their tops. When erected the frames are fastened together on top by connecting bars, both on the up-stream and down-stream sides. The up-stream bars are made stronger than those on the down-stream side, as they have to support the upper ends of the needles. The bars are made in various ways. In the dam shown in Fig. 77 the bars are pivoted at one end and provided at the other with a hook which can be attached to a pin on the cap of the adjoining trestle. In some of the earlier dams * Figs. 77, 83, and 105 are taken from the ‘‘ Paper by B. F. Thomas on Movable Dams,” Trans. Amer. Soc. C. E. for 1898. FRAME-DAMS, 393 the connecting bars had pinholes at both ends, and were placed over pins attached to the caps. The construction of the first Poirée needle-dam was soon followed by others, the details being perfected and frames of greater height being used to secure a greater depth ELEVATION LOOKING DOWN STREAM SCALE OF FEET } n i O3C9 12 1 2 3 4 & 6 7 8 9 10 u 2 13 fax) PLAN 5 SIDE ¢ ELEVATION DISC t = ESCAPEMENT POIREE NEEDLE DAM SCALE OF FEET FRONT ‘| 102 1 2 3 46 67 8 9 10 13a} keLevaTionL} # EVATIO! “ —Ss—T 0123156789101 112, SECTION Fic. 77-—Porrfe Dam. of water for navigation. The second needle-dam was built at Decise, on the Loire, in 1836. A similar work, described below, was constructed in 1838 at Epineau, on the Yonne. In 1840-45 needle-dams were built to replace the fixed weirs on the Sadne, which caused great damage during floods. Needle-dams have been erected on the following streams in France: The Seine, Marne, Oise, Cher, and Allier; and also on the Belgian Meuse and on the Main in Germany. A dam of this kind constructed in the United States is described on page 309. The Needle-dam at Epineau, on the Yonne, built in 1838, is one of the eartiest works of this kind. A description of the dam, written by M. Chanoine, the engineer 304 MOVABLE DAMS, in charge of the construction, is given in the ‘‘Annales des Ponts et Chaussées” for 1839, First Series, p. 238. The dam had a length of 230 feet and a height of 64 feet above the sill. The frames, which were placed a metre apart, were made of bar iron 1% inches square. Each frame was 7 feet high, 4 feet 7 inches wide at the base and 4 feet 3 inches wide on top. The wooden needles were 22 by 14 inches in section and 8 feet long, each weighing about 13 pounds. In several similar dams that were constructed subsequently on the Yonne, the frames were made 7 feet 4$ inches high and placed 3 feet 7 inches apart. The Needles used in Europe have generally been made of red pine. In the first dams they were only about 1% inches square and 8.2 feet high, each needle weigh- ing, when wet, about 44 pounds. As higher dams were constructed, heavier needles had to be used. The largest needles in France are 4% inches square and 16 feet 5 inches long, each weighing about 100 pounds. A needle of this size and weight can still be placed by hand, but heavier needles have to be handled by machinery. Needles 8 inches square have been experimented with in France, but abandoned as too heavy. In an American dam (page 310) needles 44” * 12” X 14’ 3”, weighing each 263 pounds when wet, have been used, but they are placed by means of machinery. The needles have a square or rectangular cross-section. For high pools the thickness of the needle is reduced according to the strain to which it is subjected, the width remaining, however, the same. Needles having a hexagonal or semi-hex- agonal section have been experimented with but have not yet been introduced. The top of the needle is formed into a handle. It is generally provided with an iron ring and sometimes with a hook serving to attach the needle to the supporting- bar. When the needles are to be released mechanically by turning the supporting- bar, those between two adjoining frames are usually fastened to the same rope, which passes through the iron rings or through eyes in the needles. This rope is attached to a hawser, one end of which is fastened on shore. By this arrangement the needle can easily be recovered. As the height of Poirée dams became greater two difficulties were encountered: Ist. The needles were often broken in handling; 2d. The leakage between the needles increased considerably. To avoid breakage heavier needles, proportioned according to the pressure they were to sustain, were introduced. In some dams a wooden bar has been placed on the up-stream side of the frames to relieve the needles of some of the pressure they have to bear. The bar is suspended by chains and bears against the needles at about one-third the height of the part under pressure. Hollow needles have been proposed, as giving greater strength for the same weight than solid spars, and it has also been FRAME-DAMS. 305 suggested for high dams to use two sets of needles, one for the lower and one for tne upper part of the dam. The leakage can be diminished by placing straw, etc., in front of the dam. Alternate needles of a ‘“‘T” form (Fig. 78), or with india-rubber facing (‘*C” in Fig. 79), have been proposed. None of these improvements suggested to avoid leakage and breakage have yet been practically introduced. Frames.—In the first needle-dams the frames were only about 7 feet high. As such dams were built later on to retain greater depths of water, the height of the frames had to be increased. In the Martot Dam, on the Seine, the frames are 11 feet high. The frames of the dam at Louisa, Kentucky (page 309) are 15.17 feet high. The simple construction of the early frames had to be modified as their height was increased. ‘‘T” or ‘*U” iron, etc., were used in the frames as giving Fic. 80.—PoIRf&E NEEDLE-DAM. greater strength for the same weight than bar iron. More bracing was also re- quired. Fig. 80* shows a modern frame. In some dams the frames are surmounted by light framework in order to raise the foot-bridge so as to be above all danger of * Figs. 80 to 93, and 98 to 1ro2, are taken from “Fixed and Movable Weirs,”” by J.. F. Vernon-Harcourt, in Minutes of Proc. Inst. C. FE. for 1880. Figs. 89 to gr are taken from a paper on the River Seine by the same author, in Minutes of Proc. Inst. C. E. for 1806 306 MOVABLE DAMS, submersion. Standards for a rope-railing were also attached to the frames on the down-stream side in order to reduce the danger to which the dam-tenders were ex- posed in handling the needles at night or in stormy weather. The chains that were attached to the caps of the frames of the early dams have been omitted in some more modern constructions in France, as the frames can be readily raised by means of boat-hooks. Improvements were soon introduced in the details of needle-dams. One of the most important was the substitution of an iron foot-bridge for the wooden planks (Fig. 81, page 308), an invention made by M. d’Haranguier de Quincerot. The iron bridge was arranged in such a manner as to fasten the frames together when up and to fall with them when lowered, partially covering them when down. The frames of the dams on the Cher are arranged in this manner. Another improvement was the introduction of a releasing contrivance, which allowed the supporting-bar between any two adjoining frames to swing loose, setting thus the needles free, which were attached to a rope and could be easily recovered. This con- trivance became more important as the height of the Poirée dams was increased. MM. Poirée and Chanoine invented such contrivances for dams in France whereby a length of dam of 130 feet could be opened in fifteen minutes, instead of requiring an hour by the primitive method of removing the needles by hand. A very simple re- lease device, invented by M. Kummer and used in dams on the Belgian Meuse, is described on page 308. * In the early Poirée dams no special provision was made to carry off flood-waters except by the overflow formed by the fixed part of the dam. As the foot-bridge of the needle-dam had to be kept low (about 12 to 18 inches above the water), it was exposed to the risk of being submerged, which would make it impossible to lower the dam. To avoid this danger the upper part of the overflow-weir was made movable by placing on its crest some kind of shutter, such as the Chanoine wicket (described on page 327), which could be readily removed. Method of Working.—Two attendants were able to perform by hand all the work of raising or lowering the first Poirée dams. Supposing the frames to be down, the attendants erected the dam in the following manner: They first raised the frame nearest the abutment (which was the last one to be lowered) by means of the chains fastened to it, or with boat-hooks, attaching it temporarily by a hook or clamp to a ring fixed in the abutment. The planks of the foot-bridge were next laid from the abutment to the erected frame, which was then firmly attached to the abutment by the up-stream and down-stream connecting-bars. The other frames were then raised and attached in succession in a similar manner. A handle with projections (Fig. 77) served to hold a frame temporarily in place until the planks were laid and the con- necting-bars were attached. In placing the needles every other one would first be put into position so as to dam the water gradually, the intermediate needles being finally placed. The needles, even including those weighing up to 100 pounds, were placed by hand in the dam by shoving them into the water so as to allow the current to bring their lower ends against the sill. In the large dams on the river Marne (France) each needle is pro- FRAME-DAMS. 307 vided with a handle and an iron hook. In placing a needle, which in these dams weighs about 103 pounds, it is held horizontally until the hook has been attached to the supporting-bar, and then the point of the needle is lowered into the current, which carries ‘it against the sill. The distance from the hook to the point of the needle is made about half an inch longer than the distance from the supporting-bar to the sill. This causes the foot of the needle to scrape along the floor before striking the sill and thus avoids all shock. When ligther needles are used they may be pushed almost vertically into the water so as to bear against the sill. The attendants soon acquire considerable skill in performing their work. They are nevertheless exposed occasionally to danger in lowering a dam at night and in stormy weather. The necessity of doing so was, however, later on almost eliminated by providing ample overflow-weirs having movable parts, which were more easily handled than needles, and by organizing a system of signals by telegraph, telephone, etc., along the river, giving ample notices of freshets likely to occur. As the weight of the frames and needles increased, some power had to be sup- plied for handling them. This has usually been done by means of a windlass placed on a little truck moving over the trestles on rails. This truck serves also for trans- porting the needles. In some cases the dam-tenders have worked from a boat placed on the down-stream side of the dam, but experience proved that they were exposed to more danger, especially in lowering the dam, in a boat than when working from a bridge. Needle-dams in Belgium (Fig. 81). In 1875-78 twenty-seven needle-dams were con- structed on the Belgian Meuse. They contain all the improvements made up to that date. Each of these works consists of : A lock, having an available length of 328 feet and a clear width of 39.33 feet; a navigable pass 150 feet long, which can be closed by a needle-dam; and an overflow-weir 179 feet long, on top of which Chano- ine wickets (page 327) are placed. The sill of the weir is laid at low-water ; the sill of the pass is placed 2 feet lower. When the dam is up the pool formed is 10.17 feet above the pass-sill. The frames of the pass are placed 3.93 feet apart, centre to centre. They are 8.36 feet wide at the base, 4.76 feet wide on top, and 11.48 feet high from the floor to the under side of the collar of the bar supporting the needles. The frame is made of wrought-iron bars. It is stiffened by a diagonal brace con- sisting of two pieces. A horizontal tie passes between the two bars of the brace, as shown in Fig. 81. The top of the frame, when up, reaches the normal level of the water in the pool. The foot-bridge is kept about 18 inches above the water by placing on top of the frame two short iron posts, each 19.7 inches long, one at the up-stream and the other at the down-stream end of the cap. The former consists of a piece of tube and is part of the arrangement for releasing the needles, as explained hereafter. The latter is made of a solid piece of iron. The axle from which the iron floor is hung connects these short posts. The total weight of a frame, including the floor, escape-bars, etc., is 1108 pounds. The up-stream journal-box for the axle on which the frame turns is let into the sill and held by screws and bands. The down-stream journal-box is bolted to the stone. These boxes weigh respectively 70 and 200 pounds, 308 MOVABLE DAMS, The frames are held rigidly together by a sheet-iron floor 3.64 feet wide. One end of each section of floor is permanently attached to a frame by the axle on which it revolves; the other end terminates in claws which grasp the cap of the next frame. The floor is connected at the abutment, pier, and lock-wall to iron bars like the caps of the frames, which are fastened to the masonry. The needles are made of red Riga fir. They are 12.3 feet long and 3% inches wide. At the point of maximum pressure and for 10 inches each way the needles are 4% inches thick. They are 3 inches thick at the bottom and 34 inches at the top. Each needle is finished at the top so as to form a handle g inches long, ending in a Fic. 81.—BELGIAN NEEDLE-DAM. ball. It is provided with an iron ring, through which a rope passes that connects the eleven needles of each bar. One end of this rope is tied to the down-stream leg of the trestle, the other end is knotted. The needles, which weigh 55 pounds apiece, are placed by hand by the dam- tender. When it is desired to release the eleven needles between any two frames, the rope connecting the needles is fastened to a hawser tied at one end to the pier or shore. The escapement is then turned and the needles are carried by the current below the dam. The escape device used in these dams was invented in 1845 by M. Kummer, the Chief Engineer of the Meuse Improvements in the Province of Liége. It is constructed in the following manner: The bar MW (Fig. 81), supporting the tops of the needles between any two frames, is connected at one end by means of a collar to the hollow tube D bearing the up-stream end of the floor-axle in such a manner that it can turn horizontally when released. At the other end it rests (when locked) against a FRAME-DAMS. 309 circular post called a jack-post, placed inside the tube Dof the next frame. A semi- circular notch is cut in the jack-post at the elevation of the support-bar. Similar notches are cut in the tube D, in whichthe jack-post is placed, and in the rear end of the collar of each support-bar, M. The head A of the jack posts, which pro- jects out of the tube D, is made square to enable the dam-tender to turn it by means of a wrench or key. When the jack-post is turned so that its notch corre- sponds: to that of the tube the supp-rt-bar of the needles becomes free and swings back horizontally, releasing the needles. Needles are used only for the pass. The movable dam placed on top of the weir consists of 39 Chanoine wickets (page 327) each 7’ 4” high by 4’ 3° wide. A 4-inch space is left between two adioining wickets. It may be closed by a board during low- water. The wickets are maneuvered from a frame foot-bridge placed on the up-stream side of the weir. The Dam across the Big Sandy River at Louisa, Ky.,* built in 1891 to 1897, is the first needle-dam constructed in the United States. It differs in several respects from similar works in Europe. It sustains a greater head of water, the needles are much wider and heavier, the trestle-frames are much lighter, and the methods of operating the dam are new. According tc the original plans, needles were to be used for the pass and wickets for the overflow-weir, but it was finally decided to use needles both for the pass and weir. We believe that this is the first dam in which this arrangement has been adopted. . The works consist of : A lock 52 feet wide by 255 feet long, located on the right bank of the river; a navigable pass, next to the lock, 130 feet long, and an over- flow weir 140 feet long, separated from the pass by a pier 12 feet wide and termi- nating at an abutment 174 feet wide, on the left bank. The total length of the masonry foundation, including the lock, is about 400 feet. The sill of the pass is about one foot below the low-water mark of recent years. The sill of the weir is placed 6 feet above that of the pass. The normal height of the pool is 13 feet above the sill of the pass. The frames are placed four feet apart between centres. Those of the pass are 15’ 2” high and 9’ 10} wide at the base. The weir frames are 9’ 8” high and 6’ 5” wide at the base. The weights of the pass and weir frames are respectively 1140 and 920 pounds. The frames are made of 4-inch steel channels, the up-stream parts being single, while those on the down-stream side are made of two pieces, set apart and trussed as shown in Fig. 4, Plate DD. The posts of each frame are connected by two horizontal braces made of angle-iron. A suitable frame for carrying the floor is riveted to the outside of the main trestle-head. The bar which connects two adjoining frames with each other when standing and supports the upper end of the needles is hinged vertically at one end at the pool level so as to swing horizontally. On the other end it is formed into a hook, on its up-stream side, which engages with a lip or projection on the next frame. A crank- * Paper on Movable Dams by B. F. Thomas, Trans. Am. Soc. C. E., June, 1898. Report of the Chief of Engineers, United States Army, 1897. 310 MOVABLE DAMS, shaped rod, called a jack-post, serves for holding in place or releasing the hook end of the bar. When the dam is up this post is kept by a Jatch from turning. When the needles are to be released the latch is raised and the jack-post is turned by a wrench so as to allow the hook end of the bar to pass through the space formed by bending the post. The frames are connected on top by a sheet-iron floor, which is hinged to and falls with them. They are also connected by the maneuvering chain. The frames are raised or lowered by means of two chain-crabs—one for the pass and the other for the weir. The former is located on the lock-wall; the latter is situated on the pier. As the frames of the pass and weir are raised or lowered by their respective crabs in the same manner, we shall only describe the method of raising those of the pass. A chain which can be wound or unwound by the crab passes over all the frames and is attached to the one furthest from the crab. This. chain passes, at each frame, over a combihed chain and _ ratchet-wheel, which is attached to the head of the frame and turns on a horizontal axis. When the pawl is out of the ratchet the chain-wheel simply turns as the chain from the from the crab is moved, without producing any effect on the frame. When the pawl is dropped into the ratchet the chain-wheel is locked, and consequently any motion of the chain from the crab will revolve the frame on its journals. The chain passes at the crab over a sprocket-wheel and drops through a hole into a recess provided for it in the masonry. The Needles are made of white pine. They are 12 inches wide. Those for the pass are 14’3” long, 8%” thick at the bottom and 44” on top, each needle weigh- ing when wet about 263 pounds. The needles for the weir are 8’3” long, 3%” thick at the bottom and 23” at the top, each weighing about 80 pounds. All of the needles are banded at the top and bottom and are provided with iron handles at the top for convenience in handling. They have also suitable attachments for connecting- chains, for placing or removing them. Shallow grooves are cut in the sides. of the pass-needles for strips of rubber, which may be placed in these grooves to prevent leakage. Thus far this has not been found necessary, the dam being remarkably tight. ‘The needles’ are placed by means of a boat on which those for the pass are stored when not in use. Method of Working.—The following operations are required in working the dam: Ist. Raising or lowering the frames; ° 2d. Placing or removing the needles. Ist. Raising or Lowering the Frames.—Two men turning the crab and a third man to connect the frames, etc., can perform this work. When the frames are down the iron floor locks the pawls in the ratchet-wheels. Consequently, as the men at the crab wind’ in the chain the frame nearest the crab starts first to rise and others. follow in turn. When the first frame is nearly vertical the attendant in charge of this part of the work raises the iron floor a few inches. The effect of this motion is to turn the pawl out of the ratchet, disconnecting thus the frame from tne motion of the chain, which now simply revolves the chain-wheel. The attendant connects PLATE DD. NEEDLE-DAM ON THE Bic SANDY RIVER AT Louisa, KENTUCKY. FRAME-DAMS., 313 now this frame with the masonry by means of its floor and then places the connect- ing-bars. By the time he has performed this work the second frame has come within reach. This is stopped and connected to the first frame in the manner just described. The remaining frames are handled in a like manner. The iron foot-bridge is prolonged to the pier or abutment, as the case may be, by a rolling foot-bridge. To lower the frames the work described is done in a reversed order. The attendant unhooks the rolling bridge and shoves it back into a recess provided for it in the masonry. He then disconnects the two frames furthest from the crab and unhooks the iron floor, which falls on the crab-chain, locking the pawl in the ratchet. The attendant pushes the last frame away from the crab while the chain is being unwound. When about 4 feet of chain have been unwound, the connections between the next two frames are removed and the pawl of the frame next to the one already being lowered is locked in the ratchet-wheel by dropping the iron floor on the crab-chain in the manner just described. This frame is pulled down by the weight of the one already descending, and so on. Several frames are usually raised or lowered at the same time, Plate DD, Fig. 1. The men at the crabs need not stop in the winding or unwinding. Should the chain break, as has happened in the first working of the dam, the frames can be handled from the needle-boat. 2d. Placing or Removing the Needles.—This has been done in two ways: Ist, directly from the boat; 2d, from the water by means of a derrick on the boat.: The first method was the one originally contemplated, but the second has been found by experience to involve less work. When the first method is adopted the needles are handled by means of two trolleys travelling on suspended tracks, one on each side of the boat. In placing the needles every fourth one is first put in position in the dam. The intermediate needles are first placed on shelves, temporarily attached to the trestles just above the water. When all the remaining needles are placed in this manner, each shelf is re- volved to a vertical position by pulling a trigger. The needles, left without support, drop into the water and are guided to their proper position by the turned shelf behind them and the needles already placed. The revolving shelves are then removed. When a rise occurs in the river, some relief may be given by opening the gates of the lock and by pushing out the heads of alternate pins, supporting them by sticks 12 to I§ inches long, placed between them and the support bar. If these measures are insufficient to keep the water from rising, the needles of the pass or of the whole dam may have to be removed. According to the original intention the needles were to be released in the usual manner by turning the jack-posts. It was feared, however, that owing to their weight the needles might get more or less injured when released, especially those falling over the weir. Another method of removing the needles was therefore adopted. Each needle is provided on top with a counter-sunk handle. A chain much longer than the dam is passed along the up-stream side of the needles and connected by hooks with their handles so as to have a considerable amount of slack chain between each pair. A long line is connected to the end of the chain. It can be wound up either 314 MOVABLE DAMS. by the engine of the boat or by a crab on the lock-wal! or on shore. As this ims is wound up the needles are pulled in succession out of their place in the dam. This method works very rapidly and satisfactorily. Drift-boom.—After severe storms the river carries a considerable amount of drift, which may injure the dam and interfere with its being lowered. To avoid this danger a drift-boom, consisting of four parallel timbers bolted’ rigidly together and having rudders at intervals of 30 feet, is placed across the river from a point some distance above the lock to the crib at the river-wall of the lock. As the river makes a sharp bend at the point of attachment the boom forms a continuation of the shore. It serves to guide the drift into the lock, where it can be held or let through as desired. The rudders are all controlled by a wire rope which connects them all and is wound on a capstan at the end of the boom. By setting the rudders at any de- sired angle the boom can be held out in the stream at any point required. Cost.—The total cost of the dam, including the pass, weir, pier, and abutment, amounted to $73,697.74, or $245.66 per lineal foot. The substructure cost $226.48 and the superstructure $19.18 per foot. li a Ue M wy , VY Nea TNO VON DB Mp 7 Viti, JEM NY gTte Ye “uy Yili Fic. 82.—BouLft GATE. Boulé Gates (Fig. 82).—In 1874 M. Boulé introduced a modification in a Poirée dam by substituting for the needles ordinary plank sluice-gates, a number of gates, placed one on top of another, being used in each bay. Each of these gates consists of a number of boards, tongued-and-grooved, and bolted together. They slide vertically between the frames and are maneuvered by a derrick travelling on top of the foot-bridge. In order to limit the transverse strains, to which the gates are subjected, the distance between the frames should not exceed one meter. Thicker boards are used for the lower gates than for FRAME-DAMS. 315 those placed at the top. For convenience in regulating the height of the pool, the upper gates may consist of single planks which can be readily placed or removed by hand. While the first cost of a frame-dam with Boulé gates is about the same as that of a needie-dam,. the former has the following advantages over the latter: Ist. It forms a tighter dam, as it has fewer joints. 2d. It can be more correctly proportioned to the water pressure to be resisted, thin planks being used for the upper and thick planks for the lower gates. 3d. It reduces the spans of the wooden members greatly, by placing them horizontally between the frames. 4th. It can be used for deeper pools. 5th. The service-bridge can be placed at a higher level above the water. 6th. No weir is required, as the whole dam forms an overflow. 7th. The level of the pool can be easily regulated. 8th. The dam is more easily maneuvered and with less danger. On the other hand, it must be stated that a needle-dam can be opened much more rapidly than a Boulé dam, as constructed at present. Compared with a dam of Chanoine wickets, Boulé’s system is found to be considerably cheaper and less complicated. By removing in succession each row of Boulé gates across the whole dam, the pool is lowered gradually and the work of raising the gates is greatly reduced. This method of maneuvering consumes, however, considerable time, 5 to 6 minutes being required for raising ‘ ene Fic. 83.—BouLft GArEes In Moskow Dams. one of the gates of the lowest tier. This objectionable feature might be removed by intro- ducing some system of escapement. Boulé gates were first used in France in the regulating portion of the Mulatiére dam across the Saéne, near Lyons. They have since been successfully used in the dams at Suresnes, Marly, etc. This system was applied by M. Janicki, in 1876, in six dams on the river Moskowa, in Russia. According to the original plans, these dams were to be provided with needles 7 316 MOVABLE DAMS. mches square. As the engineers had some doubts about being able to work needles of that size, they adopted Boulé’s system, which had just been proposed, with some modifications. instead of gates, planks about 10 inches wide are used, which bear against upright timbers resting against a sill and the top of the frame like Poirée needles (Fig. 83). Two pegs are put through every plank, one at each end. They bear on the down-stream side against Fic. 84.—CAmMERE CuURTAIN-DAM. the upright timbers, and serve as guides for the planks. On the up-stream side they form the handles by which the planks are raised, by means of hooked poles, no crab being required. The objection to the time consumed in maneuvering dams arranged according to Boulé’s system applies also to the Moscow dams, but it would seem that in this case an arrangement for permitting the planks to escape might be readily contrived. The Curtain-dam, invented by M. Caméré, was first introduced in 1876-80 in the Port o ¢ 60,9000 0 30 0 0 0 ofa 30-0. 00 of SECTION 1 foe 1 Lt SSS rhe -09-rte 09-9. 3S 2 o|efo ooo of? Cre of2 2 2 fo Pet 29000 mit 2 eg— bees ° al e - ; = 6 6 i ° ! ° | : be 1 ° = ° —~+S-Ho if ° i oO | ° t ° ! ° of ---099---> lo 1 ° ' io i 406 02 No 1 eo00 0 ' io S 3 ooco -}- 9 [J ——$—$—* t lo ‘of ' ° i | > i ELEVATION ine i, SSSreoMeo- sso se @o0o000 e2a000 0 9 0 0 59,0 0,0 0 0 00000 eo 000 cS SSS SSS Cet ean y 100| ¢-4-4 LAA UO 9] 0) — lo. 9 OP olo 29 oo 6 0 O00 0 0] 9 pre ee Fic. 86. CamEr£é CuRTAIN-DAM. Fic. 85. 318 MOVABLE DAMS. Villez dam (page 319). Having stood this test very successfully, it was used later on in the} Suresnes, Poses, and Fort-Mort dams (pages 319 to 323). M. Caméré’s invention consists in the substitut‘on of a wooden curtain that can be rolled up from the bottom, for the needles in a Poirée dam. Figs. 84 to 88 show the construction of the curtains, etc., of the Poses dam,* which are called ‘‘ double,” as each of them covers two bays of the dam. In the other two dams mentioned above, a curtain is provided for every bay. Each curtain consists of a number of horizontal wooden bars, which are fastened together on the up-stream side by two rows of bronze hinges (Fig. 86). The bars have the same length and height, but their thickness is increased from the top to the bottom, according to the pressure they have to sustain. A casting called the ‘‘ rolling-shoe”’ is attached to the bottom bar and forms the centre on which the curtain is rolled up. It rests on the floor when the curtain is down. The base of the shoe forms half the spire of an Archimedian spiral, which is completed by three flanges which surmount the upper plane surface of the shoe. The weight of the ‘* rolling- shoe” is sufficient to make the curtain unroll easily when it is being lowered. The curtain is suspended by two chains which are fastened by hooks to the fixed parts of the dam, above the water. Each of these chains is attached to a ring bolted to the upper bar in the line of the hinges. The curtain is moved by means of a special windlass (Fig. 87), which works an endless chain that passes around the curtain on its centre-line. The chain is prolonged above the curtain and is guided to the windlass by fixed pulleys. The windlass is arranged in such a manner that when the curtain is being rolled up, the up-stream part of the windlass-chain, which rises, travels faster than the down- stream part, which is lowered. This difference of velocity causes the chain to slide under the shoe. The resulting friction added to the traction of the chain makes the shoe revolve, and thus rolls up the curtain. In unrolling the curtain the down- stream part of the chain is made fast and the up-stream part is released. If the curtain is properly suspended it will move between two vertical planes. It is, how- ever, advisable to have guides to prevent any lateral motion which might be caused * Figs. 84 to 88 are taken from Dr. William Watson’s official report to the U. S. Government on ‘‘ Civil Engi+ neering, Public Works, and Architecture at the Paris Universal Exposition of 1889,” oi FRAML-DAMS, 319 by faulty construction or regulation. These guides are usually formed of angle-irons which are attached to the frames. The hooks of the chains by which the curtain is suspended are fastencd to a special iron frame (Fig. 87), which is securcd to the bridge of the dam by pins. When the curtain is to be removed, after being rolled up, it is placed with the frame from which it is suspended, on a special car (Fig. 87) running on the bridge track. After being taken out of the dam, the curtains must be hung up to dry, and cleaned. With the Caméré system of movable dam a special weir is not required, as no damage can result from the water passing over the top of the curtains. The upper Fic. 88 -—CRross-SECTION OF CAMERE CURTAIN-DAM. pool can be drawn down by rolling up the curtains to any desired height. As the water is thus discharged from the bottom of the pool, no difficulty is experienced with drift, but on the other hand, it involves the objectionable feature that scour is produced at the bottom of the curtains when they are raised. The Caméré curtains have now stood the practical test of fifteen to twenty years’ service in the dams of Port Villez, Poses, Suresnes, and Port-Mort. The Port Villez Dam was constructed in 1876-80 across the Seine at a point about 90 miles below Paris, to obtain a depth of 10} feet for navigation. It is 700 feet long and consists of two central navigable passes and a_ reguating weir on the right bank, which are separated by two piers. The sill of the passes are 13.12 feet below the upper water-level: the sill of the weir is at half this depth. 320 MOVABLE DAMS, The original plans contemplated the construction of a Poirée dam with needles 8 inches square, which were to be handled by mechanical means. Thus far this system had only been applied to lifts of about 63 feet. As M. Caméré, the engineer who designed and constructed the works under the direction of M. Lagrené as Chief Engineer, had some hesitation of using needles for the great lift required in the Villez Dam, he invented a hinged wooden curtain (page 316), which he used with Poirée frames, both in the passes and in the weir. The frames are placed 3 feet 74 inches apart. Those for the passes are 18 feet high and weigh each 4181 pounds. The weir frames are g feet 2 inches high, and weigh 798 pounds apiece. The frames are designed to present as little obstruction as possible when lowered. They lie in a recess in the masonry apron when down. » The up-stream posts have a small ‘‘ T-iron” on their face, the web of which serves as a guide for the bars of the curtains. The service-bridge is widened sufficiently to carry two tracks, by means of brackets on the down-stream side of the frames. The rails act as the braces for the frames and replace the connecting bars used in the older types of frames. The frames are raised or lowered by means of a windlass which is placed on a car that travels on one of the tracks of the service-bridge. The lowering of the heavy frames of the passes is a troublesome operation. Numerous breakages and deforma- tions of the frames, caused by their striking on stones, stumps, etc., brought down by the floods, have occurred. The Poses Dam on the Seine, about 125 miles below Paris, was constructed to replace an older movable dam. The work was completed in 1885. The dam, which extends from the left bank of the river to the point of an island (Fig. 89), has seven Fic. 89.—Posrs Dam. openings which are separated by piers. The two openings at the left bank, serving as navigable passes, are each 106% feet wide; the others have each a width of gg feet. The sills of the navigable passes and of the three passes nearest the island are 16.42 feet below the upper water-level. The two central openings have their sills 6% feet FRAME-DAMS. 321 higher than those of the other passes. The locks are located between the island, at which the dam terminates, and the right bank of the river. On account of the great height of the dam, the foundation across the whole river was carried down to an impermeable stratum of chalk, at a depth of, about 28 feet below the sills of the navigable passes. The piers (Fig. 90) are 13.12 feet wees GI Do ca cee ne nce tee mene cee eee ecnee cane mes onen senna nenene TNT ES eee pe OTT GLEN noe ON On ras csecnse neem eser = Fic. 90.—PiER oF Poses Dam. thick. Full-centred arches, 4.26 feet wide and 7.54 feet high, are constructed in the piers and abutments to permit the service-bridge to pass through them. On account of the trouble experienced in handling the heavy Poirée frames of the Villez dam, mentioned above, M. Caméré, who designed and constructed also the Poses dam, decided to use in the latter, frames suspended from an overhead bridge. When down, these frames bear against a sill and form the support for the Caméré curtains. When the dam is to be opened, the curtains are first removed, and then the frames are hoisted out of the water, so as to lie in a horizontal position below the bridge. A similar arrangement of suspended frames was suggested by M. Tavernier for the Saéne in 1873, but was not carried out. While this system has the advantage of removing the whole dam from the water when the passes are to be opened, it necessitates a high service-bridge and, consequently, long frames, if vessels are to pass under the bridge during floods. A wide bridge is constructed across the whole dam. It is composed of three lines of longitudinal lattice girders connected by cross-girders. The longitudinal girders divide the bridge into two parts at different elevations (Fig. 88); one supporting the upper, suspended ends of the frames and carrying the derrick used in removing 322 MOVABLE DAMS. the curtains; the other supporting the windlass for hoisting the frames out of the water. Each curtain in this dam is 7.47 feet wide and closes two bays. It is composed of yellow-pine bars 0.25 feet high, having a slight play between them to allow for swelling. The thickness of the bars varies from 1.57 inches at the top to 3.54 inches at the bottom of the deep bays. The upper bar is reenforced by an angle-iron, as it is exposed to shocks from floating bodies. The curtains, when rolled up, are not removed from the frames unless they require repairs. Even when the frames are hoisted up, the curtains remain attached to them. In one of the deep passes a curtain can be rolled or unrolled in about fifteen minutes. The raising and lowering of a frame requires, respectively, twenty and ten minutes. The Dam at Suresnes, a short distance below Paris, was originally constructed for Poirée needles. In 1884 it was reconstructed in order to raise the level of the pool 34 feet, to secure a minimum depth of 10} feet of water. In building the new dam M. Boulé, the Chief Engineer in charge of the work, decided to use both the gates invented by him and Caméré curtains, in order to test the two systems side by side. At the site of the dam two islands divide the river into three channels, Fig. 91. A weir 206 feet wide was Fic. 91.—SurRESNES DAM. built in the middle channel, and passes respectively 206 feet and 238 feet wide were con- structed in the right and left channels. The sills of the right pass, weir, and left pass were placed respectively 12.13, 16.25, and 17.90 feet below the level of the upper pool. A lock 525 feet long and 56 feet wide is constructed at the left bank. The weir is closed by Boulé gates, Fig. 82, page 314. Caméré curtains are used in the right pass. In the left pass, which is the principal channel for navigation, Caméré curtains and Boulé gates alternate. The curtains and gates are supported by Poirée frames. Those of the main pass are 19.5 feet high and weigh each about 4000 pounds. Each of the curtains used in this pass weighs 1600 pounds. The frames are maneuvered by means of a Megy patent windlass, which is placed on the abutment. A continuous chain unites the frames by means of link catches placed on their upper cross-braces. The portion of the chain between any two con- FRAME-DAMS, 323 secutive frames is longer than the distance between their centres. As the chain is wound up several frames are moved at a time, like the sticks of a fan. This system is similar but not as good as that used in the Louisa Dam, described on page 309. At Suresnes seven men can open a pass of 238 feet, containing 57 frames, in three hours and can raise it in five. At Louisa three men can 1aise a frame and place the foot-bridge in about a minute. The Port-Mort Dam was constructed in 1886 across the right branch of the Seine, between the Port Villez and Poses dams. It has seven passes of gg feet width, which are separated by piers 13 feet wide and are closed by Cameré curtains. The dam is very similar in design to that at Poses, except in some minor details of construction. Owing to the much greater height of the navigable level above the normal level, the piers of this dam are higher and its frames are longer than those of the Poses dam. In both of these dams a clear headway of 16} feet above the highest navigable level is provided when the frames are raised. A-Frame Dams.—This stlye of movable dam was invented by B. F. Thomas, M. Am. Soc. C. E. It consists of a number of A-shaped trestles or frames (Fig. 92) adjoining each other so as to form a sufficiently tight dam. The legs of each frame are fastened ~~ > Pasa. BOLT OR COTTER PIN SSS SS SSS UP-STREAM ELEVATION CAULKING STRIP SIDE ELEVATION GENERAL DESIGN OF AN A-FRAME Dam OF Low Lirt. Fic, 92,—THoMAS A-FRAME Dam. together at the top by plates 18-30 inches wide, which form a walk on top of the dam. To the lower end of each leg a piece having an eye is riveted, the piece being bent so as to make the eye vertical. A pin passes through this eye and connects the leg to a journal 324 MOVABLE DAMS. box, which is fastened to the floor of the dam. To enable the frames to turn without binding, the eye of the journal box must be centred at a greater distance from the floor than half the width of a frame. The up-stream box is embedded in the sill or may form part of it. The up-stream legs of the frames are made of channels to which plates are riveted. A space of about } inch may be left between the adjoinirg frames, when erected, to prevent foulirg when the dam is operated. The small amount of leakage between the plates would serve to flush out the bed between the legs. The down-stream legs may be con- structed like those on the up-stream side, or they may be latticed or made of single members. The frames may be raised or lowered by a maneuvering chain which is wound around a winch placed on the pier or wall at one end of the movable dam, and attached to the frame furthest removed from the winch. The chain passes over sprocket-wheels, one being placed on a shaft at the head of each frame. Each of these wheels has on one edge a ratchet, into which the tooth at one end of a pawl fits loosely, while the other end forms a rounded wedge. The pawl is pivoted so as to be readily lifted out of the ratchet when the wedge end is depressed. This occurs, just as the frame becomes vertical in raising, by the wedge end being pushed by a projection on the adjacent frame, made for this purpose. The wheel on top of the frame is thus enabled to run freely, but if the frame should begin to descend the pawl would become locked in the ratchet and the frame would be raised again. The pockets in the wheel are made to fit the maneuvering chain, which cannot move without also moving a trestle so long as the pawl is in the ratchet. In addition to the maneuvering chain short pieces of chains may be placed between adjacent trestles and fastened to them by eye-bolts. The length given these short chains (called fixed chains) depends on the number of frames that are to be raised at a time, or, in other words, upon the power of the winch; they must, however, be sufficiently long to permit the frames to lie flat when down. When lowered the frames are protected by the sill of the weir or pass. Instead of a chain-wheel and pawl a latch, placed and removed by hand, may be used. The advantages claimed for this style of dam are: . Simplicity of construction and operation. Lal 2. Cheapness of construction, as only a narrow foundation is required. 3. Little leakage. 4. The dam can be operated under great heads of water by two or three men, as it is raised or lowered across the current. A weir of this kind, 120 feet long and 13 feet 2 inches high, forms part of Dam No. 6 on the Ohio River, which was completed in the fall of 1904.* * See page 365. SHUTTER-DAMS. 325 CHAPTER II, SHUTTER-DAMS. Early Shutter-gates.—For some centuries gates turning on horizontal axles, placed near their tops, have been used in Holland to let the interior water from rivers and canals escape into the ocean at low tide while preventing the water from the sea from entering at high tide. Such a gate having its axle placed at one-third its height from its base, which corresponds to the centre of pressure when the water rises to the top of the gate, was proposed by M. de Cessart, in a ‘‘ Description of Hydraulic Works,” printed in 1808. M. Petitot suggested, in 1825, a similar gate for regulating automatically the level of a stream of water.* In a memoir on establishing internal navigation be- tween Paris and Rouen, M. Frimot proposed, in 1827, placing in fixed dams several gates, one on top of the other, each turning on a horizontal axis. The turning of these gates was to be controlled by floats. In 1837, shutters turning on horizontal axles were placed under the bridge of Riom (France). + These gates opened automatically during freshets and had to be set up again by hand. The first dam constructed by movable shutters was probably the one across the river Orb (France), described by Delalande in his ‘‘ Traité des Travaux de Navigation,” published in 1778. This dam was raised 3 feet by movable wooden shutters hinged to the top of the dam and held by props placed on their down-stream side. The sluice-openings were closed by stop-planks (poutrelles) placed horizontally, one on top of another, and attached to each other by chains. When the water was to be low- ered these stop-planks were allowed to escape by a suitable contrivance and the shutters on top of the dam were lowered by hand when the water had subsided sufficiently. Thénard Shutters.—M. Thénard applied the movable shutters just described, with some improvements, on several dams on the river I'Isle (France). He found that the height of these dams, 6.56 feet above low water, while insufficient for internal naviga- tion, caused inundations in times of freshets. To avoid this trouble M. Thénard deter- mined to reduce the height of the fixed dam to 3.93 feet above low water, and to obtain the remaining height required for navigation by means of movable shutters similar to those placed on the crest of some of the dams in the river Ord. He used this construction for the first time in 1831 in the dam of Saint-Seurin. The principal improvement which M. Thénard introduced was a tripping-bar, by means of which the props could be ‘‘tripped ’’ in succession, allowing the shutters to fall down. The end of this bar consisted of a rack, which could be moved by a pinion placed in a well in the abutment. * Mémorial du Génie, for 1825, Vol. VII., page 161. + Annales des Ponts et Chaussées, for 1842, 1st Series, page 231. 326 MOVABLE DAMS. : While the device just described made the lowering of the dam a very simple operation, much difficulty was encountered in raising it against the current. To obviate this trouble, M. Mesnager advised M. Thénard to place counter-shutters falling up- stream above the remaining shutters. The former were to be raised by the current itself and to be kept by stop-chains from rising too high. This plan was carried out successfully on three dams built on the I’Isle in 1839-1841. Each of these dams was 230 feet long, including the pass and lock. The shutters were bolted to a wooden sill which was fastened to the top of the masonry dam. They were 6.56 feet wide by 3.28 feet high. Those falling down-stream were supported, when up, by wrought-iron props, whose feet bore against iron hurters (shoes) or sills. The iron tripping-bar was moved by turning a pinion on the river bank in the manner already explained. It had a projection for every prop. For every 14 inches of motion it tripped one shutter. After all the shutters were lowered the tripping-bar had to be moved back to its original position. The up-stream shutters, when lowered, were held in place by spring-latches, which could be released by a tripping-bar. A forked chain, fastened to the floor, kept each shutter from rising above a desired point. When these shutters were up the lock-keeper could walk almost dry-shod on the weir and raise the down-stream shutters by hand. When both sets of shutters were up he equalized the level of water between them by opening small valves in the up-stream shutters. He finally pushed the counter-shutters down with a pole. The whole operation of raising one of these dams could be performed by one man in about sixteen minutes. In 1843, M. Thénard erected at the St. Antoine Dam shutters 5.57 feet high by 3.82 feet wide. In this case he constructed a small sheet-iron foot-bridge on top of the counter-shutters, from which the tender could raise the down-stream shutters. Having applied movable shutters 5.57 feet high successfully, M. Thénard obtained, in 1846, authority to carry out his system on the Seine near Montereau. Accord- ing to a memoir which he prepared he intended, in this case, to use shutters 7.54 feet high by 5.08 feet wide, and counter-shutters 7.04 feet high by 5.02 feet wide. The apron was to have a length of 36 feet. Some improvements were to be introduced in the manner of releasing and lowering the counter-shutters. The main shutters were to be raised from a boat. Before he could carry out his project M. Thénard was put on the retired list. His successor, M. Chanoine, introduced several modifications before such a dam was actually built in 1850 across the Seine at Courbeton. Although Thénard’s system of movable dams has been used successfully, the counter-shutters form rather an objectionable feature. The stop-chains, their attach- ments, and the hinges of these shutters are subjected to great strains when the shutters are suddenly stopped at the proper height. Breakage of these parts at any one shutter delays the erection of the whole dam. It has also been found difficult to make the temporary dam, formed by the counter-shutters, sufficiently tight. Thénard shutters have been used, with some modifications and improvements, on dams in India.* In the Mahanuddee Dam (Fig. 93) ten openings, 50 feet in width, * “Movable Dams in Indian Weirs,’”’ by R. B. Buckley, Minutes of Proc. Inst. C. E. for 1880, Vol. LX., p- 44. Fig. 93 is taken from this paper. SHUTTER-DAMS. 327 are each closed by seven pairs of shutters, those falling down-stream being g feet high. In the Sone Dam sixty-six openings, 20$ feet wide, are each closed by a single pair of shutters, those on the down-stream side being 9$ feet high. To regulate the rising of the counter-shutters, and to avoid the heavy shocks to which they would be subjected if stopped suddenly, hydraulic brakes are attached to their up-stream side. Each of these brakes consists of a cylinder full of water, in which a piston, moved by the shutter in rising, travels. A number of small escape orifices for the water are made in the Y IS Vey) a ‘7, Pot 1, Ya, +/4, Yet. YSIS 4, Us LAMA AL 4) 4, o Z yy SA/ Lele iy, LA foley Up teppei the Opt, Wit ibit ili YY hey LY DN A fit Z ALTA MAA MAL 1 AT Ve dO Ef 6 VAM IGLAIV YS LL St. Fic. 93.—THENARD SHUTTER-DAM. cylinder and arranged in such a manner that the vent of the water is diminished as the piston rises, and the checking force of the brake, therefore, is increased. Chanoine Wicket-dam.—The objection to counter-shutters mentioned above in- duced M. Chanoine to substitute for them in the Courbeton Dam across the Seine a Poirée needle-dam, which serves to hold back the water while the shutters on the weir are being raised and furnishes a bridge from which this operation can be per- formed. There still remained, however, the difficulty of raising the last shutter on the weir on account of the leakage through the needle-dam. In 1852, M. Chanoine overcame this difficulty by raising the axle of the shutter to a point between one- third and one-half of its height, and supporting it on a horse or trestle which itself could revolve on an axle fixed on an apron of the dam when the prop was with- drawn. This invention was carried out practically for the first time in 1857 in the dam of Conflans, on the Seine. Another engineer, M. Carro, appears to have invented a similar shutter about the same time. The term ‘‘ wicket ’’ has been applied in the United States to a shutter revolving on an axle placed near its middle. Described in detail, a Chanoine wicket consists of three parts (Figs. 94, 95, and 96): A rectangular panel of wood or iron; the horse, or trestle, supporting the axle of the shutter, and the prop holding up the horse and having its foot bearing against a cast-iron shoe, called a ‘‘hurter” (in French ‘‘heurtoir’”’) fixed to the apron. The parts of the shutter above and below the axle 328 MOVABLE DAMS. are called respectively the ‘‘chase’’ and the ‘‘breech.” Two maneuvering chains are usually attached to the shutter, one to the top and the other to the bottom. Several wickets, placed side by side, form the dam. To prevent the panels from interfering with each other by swelling, etc., they are placed about 2 to 4 inches - we twee wr PCF Fic. 94.—CHANOINE SHUTTER-DAM ON NAVIGABLE PAss ON THE UPPER SEINE. Fic. 95.—CHANOINE SHUTTER-DAM ON NAVIGABLE PASS ON THE MARNE. apart. When the leakage between the wickets is greater than the minimum flow in the river the spaces between the wickets can be closed by needles or by nailing strips of wood to the shutters. The axles of the weir-wickets are placed so that they will revolve automatically when the water reaches a certain height, but those of the pass are attached at the centre of the shutter. The pass wickets do not oscillate, therefore, when the water rises. They can be readily lowered by the tripping-bar when required. When the prop is tripped by moving it sideways, it slides forward on a casting joined to the hurter, called the slide, and is 329 HUTTER-DAMS. § {06gi NI G@LonULsNoD) INIGS WiddqQ] FHL NO way SIVIONY,T Vv LYOg ao SSVq ATAVOIAVN YOr Ww vd-4¥aLLaHs INIONVHD—-"96 ‘org 330 MOVABLE DAMS. followed by the horse. The shutter falls on top and covers them. This method can only be used, of course, when there is sufficient water on the apron to act as a cushion. If the water on the apron is not deep enough for this purpose the fall of the wicket must be broken by means of the maneuvering chains. The tripping-bar moves horizontally on the apron. It has a projection for each prop. They are placed in such a manner that at first only one prop is tripped at a time, then two, and finally three or four. By this arrangement the pool is drawn down gradually and the effort required in moving the tripping-bar is reduced. As the tripping-bar must be pulled back to its original position when the dam is a it must either be placed in a special channel on the apron or the tops of the props must be curved at the top as shown (Fig. 95), in order not to interfere with the tripping-bar when they are down. The tripping-bar is sometimes placed on rollers to facilitate its motion. One end of the tripping-bar is formed by a rack which engages with a pinion fixed on a vertical shaft and placed in a well built in the masonry of the abutment. To raise the dam each wicket is brought to a horizontal position, or, as it is called, ‘‘ put on the swing,” by pulling the breech-chain from the service-bridge or a boat until the horse is up and the prop has fallen into its resting-step. If the breech-chain is pulled up too much there is some difficulty in afterwards raising the wicket to its vertical position. To avoid this trouble lugs are sometimes cast on the horse to confine the position of the wickct within 15° of the horizontal, when on the swing. When a foot-bridge is provided there is, however, no difficulty in raising the wickets by means of the two maneuvering chains and the lugs on the horse are omitted, as they have some disadvantages. After the wickets have all been brought to the swing, in which position they offer very little resistance to the current, they are rapidly raised by pulling the chase-chains until the wickets strike against the sill. When in position in the dam they are inclined about 20° from a vertical plane. Movable counter-weights are sometimes attached to the wickets to assist in raising them. In some Chanoine wicket-dams no service-bridge is provided, the maneuvering being done entirely from a boat. In others a foot-bridge is used only for the weir, the pass- wickets being maneuvered by means of a boat. In each of these cases the details of maneuvering differ slightly from the manner we have described. Thus, when a boat is used for the weir and the pass, the wickets of the former are first put on the swing, but those of the latter are erected at once. Inthe dams built in 1860 on the upper Seine and Yonne a boat was used for the pass and weir, but later on, in 1869, foot-bridges were constructed for the weirs. The ordinary tripping-bar of the Chanoine wicket-dam can only be operated for a certain length of pass. By using two of these bars, one operated from each side of the pass, this length can be doubled. While having the advantage of lowering a dam very rapidly when all goes well, any obstruction that might get in the channel of the tripping-bar or in front of a hurter would prevent the lowering of the dam. For this reason M. Pasqueau, in constructing a movable dam across the Saéne near Lyons (page 331), decided to dispense with the tripping-bar and to arrange the wickets so that each could be lowered separately. He accomplished this by devising a special double-grooved hurter and slide (Fig. 97), in which a step @ is placed in front of the step a on which the prop rests. When a wicket is to be lowered it is first put on the swing. The breech-chain is then pulled. SHUTTER-DAMS. 331 This drags the prop from its rest and lets its foot fall to the lower step 2. As the face of this step is inclined so as to offer no support, the prop slides down a passage in the hurter and down ‘‘the slide” behind the hurter until the wicket has been lowered. Chanoine wickets, having their axis of rotation placed at 4 to $ their height, at the centre of pressure of the water, open freely when the water rises above their crest, but do not close rapidly enough when the level of the upper pool falls, and cause thus a loss of water. This trouble has been removed and the raising of the k Fic. 97.—PASQuEAU HuRTER. shutters facilitated by placing one or two butterfly (flutter) valves near the top of the shutter (page 335). These valves (which are diminutive shutters about 3 feet high by 2 feet wide, revolving on horizontal axles) open when the shutter is being raised, and thus diminish the resistance. They regulate the level of the upper pool by opening and closing in a much more rapid manner for small variations than can be done by allowing the whole shutter to oscillate. M. Chanoine’s system has been largely used for movable dams on the upper Seine, Loire, Saédne and Meuse. While it is more complicated and expensive than the systems of frame-dams which we have described, it has the advantage of permitting a much more rapid opening of the dam. When used with a maneuvering-boat this system is applicable to rivers carrying much drift, where any system of frame-dam would fail. It is for this reason that Chanoine shutters were used in the movable dams constructed on the Kanawha and Ohio rivers in the United States. La Mulatiére Dam, near Lyons, was constructed in 1879-81 across the Sadne River at its junction with the Rhone. As the latter is a torrential stream subject to rapid rises and falls and often forces back-water into the mouth of the Saédne, the dam was in the peculiar position of being exposed to sudden rises as well from below as from above. A sudden fall in the Rhone necessitated the rapid erection of the dam to maintain the required depth in the Sadne. The dam had, therefore, to be constructed so that it could be rapidly raised or lowered. To meet these conditions M. Pasqueau, the engineer in charge of the work, in- troduced various modifications in the system of Chanoine wickets, which was used, by inventing new details for the construction and devising new methods of maneuvering. As a great deal of gravel was carried by the stream, M. Pasqueau dispensed with the tripping-bar, which might have easily been obstructed, and arranged the wickets to be raised or lowered from a maneuvering-bridge. This was made possi- ble by using a double-stepped hurter or resting-shoe for the props, described on 332 MOVABLE DAMS. page 331. The ordinary tripping-bar cannot be used for passes much over 150 feet wide. With Pasqueau hurters the width of the pass need not be considered. In the Mulatiére dam it is 340 feet wide, no piers being placed in the stream. Iron wickets are used in this dam, as those of wood only last for ten years. The panels are formed of two ‘‘U” irons, 2.95 feet apart, covered by ~;-inch plate iron, projecting 10 inches beyond the uprights, supported by braces, and having angle irons put on the edges. They are 14.3 feet long and 4.6 feet wide. atety Top of| in Cubic} Feet of Sante Pressure, |Pressure, essary |* Sues Daun in vee of | Masonry. Left Right. | Total ba erg ae In Feet|In Tons] In Feet | In Tons Eaui- TUES Sele Sey in Feet, | in Feet. | in Feet. Full, in | Empty, | of Ma- | of 2000} of Ma- | of 2000 /librium.| ‘78 Feet. in Feet. | sonry.| lbs. sonry. lbs. oO ° ° 17.40 1.34 18.74 ° 9-37 | 9-37 0.0] 0.00 0.0 | 0.00 ]0.00 | 0.0 Io 25 83 19.72 1.52 21.24 200} 10.73 | 10.09 g.1| 0.57 10.8 0.68 |0.13 | 26.7 20 100 667 22.35 1372 24.07 426] 11.62 | 10.89 | 19.6] 1.23 22.8 I.43 | 0.23 8.5 30 225 2250 25.29 1.94 27.23 679] 12.13 | I1.79 | 33.1] 2.07 34.9 2.18 | 0.33 4.7 4o 400 5333 28.69 2.21 30.90 973| 12.57 | 12.85 | 49.1] 3.07 47-4 2.96 |0.41 B'S 50 625 | 10417 | 32.53 | 2.50 | 35-03 | 1303] 13.01 | 14.02 | 65.9] 4.12] 59.5 | 3.72 |0.48 | 2.6 60 goo 18000 | 36.83 2.83 39.66 | 1674] 13.56 | 15.35 | 82.2] 5.14 70.8 4-43 |0.54 2.3 7O | 1225 28583 | 41.75 3.21 | 44.96 | 2098] 14.48 | 16.86 | 96.6] 6.04 | 81.7 5.11 0.58 | 2.1 80 1600 | 42667 47.31 3.64 50.95 | 2577] 15.83 | 18.57 | 108.5] 6.78 | 91.7 5-73 |0.62 2.0 go 2025 60750 53-61 4.12 57-73 | 3119| 17.74 | 20.51 | 117.2] 7.33 | 100.9 6.31 |0.65 1.9 100 2500 83333 60.75 4.67 65.42 | 3734] 20.39 | 22.71 | 122.1, 7.63 | 109.5 6.84 | 0.67 1.9 IIo 3025 | I10QI7 68.84 5.29 74-13 | 4430] 23.91 | 25.19 | 123.6] 7.73 | 117-3 | 7-33 | 0.68 2.0 120 3600 | I44000 78.00 6.00 84.00 | 5221] 28.40 | 28.02 | 122.6; 7.66 | 124.3 7.77 |0.69 2.0 130 4225 | 183083 88.39 6.80 95-19 | 6116} 34.05 | 31.21 | 119.1] 7.44 | 130.6 8.16 | 0.69 2.1 140 4900 | 228667 | 100.15 7.70 | 107.85 | 7129] 40.95 | 34.83 | 113.8] 7.11 | 136.5 8.53 | 0.69 2.3 150 5625 | 281250 | 113.49 8.73 | 122.22 | 8278] 49.31 | 38.94 | 107.0] 6.69 | 141.7 8.87 |0.68 2.5 160 6400 | 341333 | 128.60 g.go | 138.50 | 9581] 59.29 | 43.59] 99.1] 6.19 | 146.5 9.16 | 0.67 235 170 7225 | 409417 | 145.72 | 11.21 | 156.93 | 11055] 71.05 | 48.85 | 90.3] 5.64 | 150.9 9-43 | 0.65 2.9 180 8100 | 486000 | 165.14 | 12.70 | 177.84 | 12728] 84.83 | 54.82 | 81.4] 5.09 | 154.8 9.68 | 0.64 3.2 Igo go25 | 571583 | 187.10 | 14.40 | 201.50 | 14621] 100.82 | 61.59 | 72.6) 4.54 | 158.3 9.89 | 0.62 3.6 200 | 10000 | 666667 | 212.00 | 16.30 | 228.30 | 16765 | 119.30 | 69.24 | 63.6] 3.98 | 161.4 | 10.09 |0.60 | 4.0 The Specific Gravity of the Masonry = 2. TABLE IV. (See page 32.) THEORETICAL PROFILE, BASED ON PROFESSOR RANKINE’S LIMITS AND CONDITIONS. Distance | Distance ; Maxima Pressures, Depth Hos. Moment Joint Rererrep To a VER- Front gon —_ te Factor Water| Thrust | of Water, TIGRE AIS. Total | Face to | Faceto| Reservoir Reservoir Fric- | 62h Below |of Water,| in Cubic Area in] Line of | Line of Full. Empty. tion nec-|, aint Top of |inCubic| Feet of ane tS Pressure] essary "Bye Ane econ BENE! ack Right, | Total eet. | Reser | Reser | tn Feet(In Tons| In Feet |In Tons Equi- om = , ? 2 mf 2 i f Ma-| of f Ma- : ing. in Feet. | in Feet. | in Feet. Pall is ue: ented : Ibs. Sante tha mati 0.0 ° oO 18.74 | 0.00 18 74 ° 9.37 9-37 0.0] 0.00 0.0 | 0.00 |0.00 | 0.0 26.5 175 I551 18.74 | 0.00 18.74 497 6.25 | 9.37 | 53.0] 3-31 26.5 1.66 |0.35 3.0 40.0 400 5333 25.08 0.00 | 25.08 792 8.36 | 9.99 | 63.1] 3.94 50.8 3.18 |0.51 2.2 50.0 625 IO4I7 31.17 0.00 31.17 | 1074} 10.39 | 11.08 | 68.9] 4.31 64.4 4.03 |0.58 2,1 60.0 goo 18000 37.92 0.00 37.92 | I41g| 12.64 | 12.60 | 74.8] 4.68 75.1 4.69 | 0.63 2.0 70.0; 1225 28583 45.52 1.04 | 46.56 | 1842] 15.52 | 15.52 | 79.1] 4.94 79.1 4-94 |0.66 | 2.0 80.0; 1600 42667 52.83 1.64 54.47 | 2347] 18.16 | 18.16 | 86.2] 5.39 86.2 5.39 |0.68 2.0 go.0] 2025 60750 60.16 2.04 62.20 | 2930] 20.73 | 20.73 | 94.2] 5.89 Q4-2 5.89 | 0.69 2.0 100.0| 2500 | 83333 | 67.36 | 2.29 | 69.65 | 3589| 23.22 | 23.22 | 103.1] 6.44 | 103.1 6.44 |0.69 | 2.0 I10.0| 3025 | II0gI7 74.52 2.46 76.98 | 4322] 25.66 | 25.66 |112.3| 7.02 | 112.3 7.02 |0.70 2.0 120.0] 3600 | 144000 | 81.65 2.58 | 84.23 | 5129] 28.08 | 28.08 | 121.8| 7.61 | 121.8 7.61 10.70 | 2.0 130.0| 4225 | 183083 go. 36 3.38 93-74 | 6018| 32.07 | 31.25 |125.0] 7.81 | 128.4 8.03 |0.70 | 2.1 140.0] 4900 | 228667 | 100.24 4.53 | 104.77 | 7OII| 37.23 | 34.92 |125.0| 7.81 | 133.8 8.36 | 0.70 2.1 150.0] 5625 | 281250 | 110.55 5.64 | 116.19 |} 8116] 42.81 | 38 73 |125.0] 7.81 | 139.7 8.73 | 0.69 2.2 160.0] 6400 | 341333 | 121.28 | 6.72 | 128.00 | 9337] 48.78 | 42.66 |125.0| 7.81 | 145.9 | 9.12 [0.69 | 2.3 170.0] 7225 | 409417 | 132.40 7.78 | 140.18 | 10078] 55.12 | 46.72 | 125.0] 7.81 | 152.3 9-52 |0.68 2.4 180.0] 8100 | 486000 | 143.91 8.82 | 152.73 | 12142} 61.80 | 50.90 | 125.0] 7.81 | 159.0 | 9.94 [0.67 | 2.5 190.0] go25 | 571583 | 156.16 | 11.91 | 168.07 | 13746] 69.25 | 57.23 | 125.0] 7.81 | 160.0 | 10.00 |0.66 | 2.6 200.0] 10000 | 666667 | 168.93 | 15.86 | 184.79 | 15510] 77.32 | 64.49 |125.0| 7.81 | 160.0 | 10.00 | 0.65 2.8 The Specific Gravity of the Masonry = 2. 39° APPENDIX, TABLE V. (See page 6.) M. KRANTZ'S PROFILE-TYPE. Jomvr REFERRED To a pias Dante Maxima Pressures. ee VERTICAL AXIS. FE ae Back of |F Depth Vertical | Horizon- Monenk | Pacete Face to Fric- ecror af Water- |tal Thrust] of Wrater Total | Line of | Line of | Reservoir Reservoir tion | Safety Water,| Pressure, | of Waters) i, Cubic’ : Area, in | “Pres. Pres- ull. Empty. | neces-iagainst in. | in Cubic | in Cubic | 4 | Left | Right | po4,) | Square zs Metres of| Metres of| Metres Of o¢ Axis,lof Axis, “24 | Metres, | SUTS Sure: BABY, | Vere Metres Masonry. | Masonr Masonry. oR in Reser- | Reser- In In In In for | turn- y y Wetes Mees Metres. voir voir | Metres | Kilos |Metres | Kilos|Equi-| ing. _ Pee Full, in |Empty, in} of Ma- |perSq.| of Ma-|perSq.| lib- Metres. | Metres. | sonry. | Cent. | sonry. | Cent. | rium. oO 0.00 0.00 0.00] 5.00) 0.00] 5.00} 17.50} 2.50 2.50 | 7.00} 1.61) 7.00} 1.61] 0.00] 0.0 5 0.20 5.43 9.06] 5.29) 0.14) 5.43) 43.21] 2.60 2.64 8.95] 2.06] 8.59] 1.98] 0.12) 13.4 Io 1.59 oI. 74 72.46] 6.16] 0.55| 6.71! 73.19] 2 67 3.13 | 18.05! 4.15] 13.09] 3.01] 0.29! 3.8 15 5-41 48.91 244.57] 7-65} 1.24] 8.89] 111.74] 3.00 3.93 | 26.09! 6.00] 16.59] 3.82] 0.42) 2.4 20 I2.95 86.96 579-71] 9.84] 2.23] 12.07] 163.83} 3.90 5.21 | 30.22) 6.95] 19.00] 4.37; 0.49) 2.2 25 25.46 | 135.87 | 1132.24] 12.85] 3.50] 16.35] 234.33) 5.65 6.87 | 30.51] 7.02] 21.21] 4.88) 0.52) 2.3 30 44.51 | 195.65 | 1956.52] 16.91] 5.09) 22.00] 329.60, 8.60 g.00 | 28.23] 6.49] 23.07; 5.31) 0.52) 2.6 22.50] 7.00) 29.50 35 71.57 | 266.30 SOOO tas ce) (8 .00)|(31 . 50) 457-31) 13.13 | II.71 | 24.03) 5.53} 25.11] 5.78) 0.50) 3.2 4o | 141.10 | 347-83 | 4637.69] 28.50) 11.33] 39.83] 635.61] 19.09 | 17.01 | 21.84] 5.02] 22.98] 5.29) 0.45! 4.2 45 | 202.73 | 440.22 | 6603.26) 33.50; 14.67) 48.17] 855.61) 23.62 | 21.21 | 23.29] 5.35] 24.15] 5.55] 0.41; 4.8 50 | 271.58 | 543-48 | 9059.97] 38.50] 18.00] 56.50/1117.31) 28.16 | 25.31 | 25.07| 5.77} 26.10] 6.00) 0.39) 5.3 The Specific Gravity of the Masonry = 2.3. TABLE VI. (See page 6.) PROF. A. R. HARLACHER’S PROFILE-TYPE. 7 .__,| Jonr REFERRED TO VER- a Maxima PREs- wae H -| Vi 1 Dist Dist eee tal Com cotips=! FICAE QOS: Total ion font” SuEES pao Factor paatal Depth | ponent | nent of Total | Weight) Front Back Reser- | Reser- lof Fric- of Joint of |ofWater-| Water- 7 Area of | of Ma-| Face to| Face to aie voir tion | Safety Below Water,| Pres- Pres- Left | Right Total _Profile, | sonry, | Line of Line of Full mot neces- | 28ainst Top of in _sure, | sure, | of Axis, |of Axis, in” [in Squarejin Tons| Pressure, | Pressure, : pty. sary for ver- Dac, A Metres.| in Tons | in Tons in in Metres. | Metres. of 1000 |Reservoir| Reservoir|In Kilos./In Kilos.| Equi. | tut- Metres of 1000 | of 1000 | Metres. |Metres. 7 Kilos. | Full, in |Empty, in| per per |librium,| #8- U Kilos. Kilos. Metres. | Metres. [Sq Cent. Sq. Cent. , 0.00 | 0.00] 0.0 0.0 | 4.00] 0.00] 4.00 0.00] 0.0} 2.00 2.00 | 0.00] 0.00] 0.00} 0.0 2.50 | 0.00] 0.0 0.0] 4.00] 0.00 | 4.00] 10.00) 22.0} 2.00 2.00 | 0.55 0.55 | 0.00 | 0.0 5.00} 2.50) 3.1 0.0 | 4.00 | 0.00 | 4.00 | 20.00) 44.0 1.94 2.00 1.12 I.10 | 0.07 | 33.3 7.50 | 5.00; 12.5 0.0} 4.20] 0.00] 4.20] 30.20) 66.4) 1.87 2.10 | 2.10] 1.58 {0.19 | 6.9 10.00 7.50) 28.1 0.0| 4.75 | 0.00] 4.75 | 41.35} 90.9 1.87 2.12 3.11 2.55 | 0.31 3.4 12.50 | 10.00] 50.0 0.0 | 5.65 | 0.00 5.65 54.35| 119.5 2.02 2.22 3-90 | 3.43 | 0.42) 2.4 15.00 | 12.50) 78.1 0.0 7.05 | 0.00 7.05 70.15] 154.3 2.47 2.47 4.13 4.16 | 0.51 2.2 17.50 | 15.00) 112.5 0.7 8.75 | 0.00 8.75 89.85] 197.6 9:17 297 4-13 4:75. | O57 2.1 20.00 | 17.50] 153.1 3.0 | 10.45 | 0.15 | 10.60 | 114.05] 250.8 3.80 3-35 4.42 5.00 | 0.60; 2.1 22.50 | 20.00] 200.0 7.6 | 12.12 | 0.40 | 12.52 | 142.95} 314.4 4.36 4.06 4.91 5.16 | 0.62 4,2 25.00 | 22.50} 253.1 14.8 | 13.80 | 0.75 | 14.55 | 176.75] 388.8 5.13 4.88 5.24 5-34 | 0.63 2.1 27.50 | 25.00) 312.5 25.2 | 15.50 | 1.20 | 16.70 | 215.75] 474.6 5.90 5.85 5.64 5.40 | 0.62 3.4 30.00 | 27.50) 378.1 39-5 | 17-19 | 1-70 | 18.89 | 260.25) 572.7 6.79 6.84 6.00 5-53 | 0.62 2.2 32.50 | 30.00) 450.0 58.3 | 18.88 | 2.35 | 21.23 | 310.40] 683.0 Tsh7 7.92 6.28 5.67 | 0.61 2.3 35.00 | 32.50) 528.1 81.8 | 20.57 | 3.10 | 23.67 | 366.52) 806.5 8.93 9-13 6.49 5-74 | 0.60 2.4 37.50 | 35.00] 612.5 | TI1.2 | 22.26 | 4.00 | 26.26 | 428.92] 943.8) 10.13 10.48 6.73 5-75 | 0.59] 2.5 The Specific Gravity of the Masonry = 2.2, APPENDIX. 391 TABLE VII. (See page 6.) M. CRUGNOLA’S PROFILE-TYPE. Dist: f the Line of : ; i Depth Weight Pressure from ‘the Cents saa Poa ee Bonpavae oe Coefficient of Length of Li of Metre of the Joint. . of Friction Water,| Joint, in in Tons cE _ necessary in Metres. lbs.* Reservoir | Reservoir for Equilib- Metres, BROS 8; Full. in. | Empty. in |. At Front At Back Of the Resultant of all the rium. Metres. Metees, Face, in Kilos.|Face,in Kilos.| Forces in Tons of 2205 Ibs.* Io 6.00 155.82 0.00 0.00 0.000 0.000 155.8 50.0 0.321 15 8.58 239.66 1.00 1.25 5 832 5.232 239.6 112.5 0.469 20 12.52 360.98 1.47 2.20 6.482 5.922 304.4 200.0 0.549 25 16.72 529.11 1.85 2.91 7 186 , 6.468 543.1 312.5 0.575 30 21.20 747.15 2.05 3.12 7.821 6.936 781.1 450.0 0.576 35 26.96 1018.32 1.95 4.20 7.601 7.309 1083.3 612.5 0 565 4o 33.28 1364.70 1.70 4.80 7.480 7.648 1476.7 800 0 0.542 45 39.93 1785.66 I 50 5.20 7.664 7 965 1968.1 1012.5 O 5I4 50 46.92 2285.05 I.10 5-45 7.721 8.265 2565.0 1250.0 o 487 * Ton =1 cubic metre of water = 2204.737 lbs, The Specific Gravity of the Masonry = 2.3. TABLE VIIL (See page 28.) : THEORETICAL PROFILE No. 1 oS - Joint REFERRED TO a VER- Distance | Distance Maxima Pressur Coeffi y Horizon- eee from. from cee a dent of Factor Wate oa Moment Total neo ae Reservoir Reservoir Fric- ° Below Bld of Water, Area, in Line ae Line e Full. Empty. tion nec-| Safety Topst in Cubic eer Left, Right, | Total, eae Pressure,| Pressure, ooo against in’ | Feet of Masonry. in Feet. | in Feet. | in Feet. ? eos Reser ae ie ae een In Feet | In Tons Equi- le pes aay Fest. in Bee, eoney. ; ibs, cone, a librium | ing. 0.0 oO ° 18.74] 0.00 | 18.74* 0.0; 9.37 9-37 0.0] 0.00 0.0 | 0.00 0.00} 0.0 37-1 295 3648 18.74] 0.00 | 18.74 | 695.3] 4.12 9-37 | 112.3] 8.19¢} 37.1 | 2.71 0.42} 1.8 50.0) 535 8929 24.76| 0.00 | 24.76 | 975.8] 5-79 g.82 | 112.3] 8.19 | 63.9 | 4.66 | 0.55] 1.6 60.0 7a 15429 30.47| 0.00 | 30.47 |1252.0 7-44 10.71 112.3] 8.19 78.1 | 5.69 0.62 1.6 70.0) 1049 24500 36.87] 0.00 | 36.87 |11588.7) 9.43 12.02 | 112.3] 8.19 88.1 | 6.42 0.66 |) 2.6 80.0, 1370 36571 43.87] 0.00 | 43.87 |1992.4] 11.84 13.68 | 112.3) 8.19 97.2 | 7.09 0.68 | 1.6 90.0} 1734 52071 51.39] 0.00 | 51.39 2468.7] 14.65 15.65 | 112.3) 8.19 | 105.0 | 7.66 0.70 | 1.7 100.0] 214! 71429 59-44] 0.00 | 59.44 |3022.8} 17.94 17.85 | 112.3} 8.19 | 112.8 | 8.22 0.71 | 1.8 110.0] 2591 | 95071 68.02] 0.00 | 68.02 |3660.1| 21.73 20.32 | 112.3] 8.19 | 122.2 | 8.91 | 0.71 | 1.8 120.0] 3084 | 123429 77-15] 0.00 | 77.15 /4386.0] 26.04 22.97 | 112.3] 8.19 | 127.3 | 9.28 0.70] 1.9 130.0] 3619 | 156929 | 86.73] 0.00] 86.73 |5205.4) 30.77 | 25.81 | 112.3] 8.19 | 134.4 | 9.80 | 0.69] 2.0 140 0] 4197 | 196000 | 96.72] 0.00 | 96.72 [6122.6] 35.89 | 28.82 | 112.3) 8.19 | 140.4 |10.24f | 0.68 | 2.1 150.0] 4818 | 241071 | 107.25] 2.02 | 109.27 |7152.6] 41.61 33.96 | 112.3] 8.19 | 140.4 |10.24 0.67 | 2.2 160.0] 5482 | 292571 | 118.21] 4.34 | 122.55 |8311.7| 47.88 39-47 | 112.3} 8.19 | 140.4 |10.24 0.66 | 2.4 * The top width was made equal to that of Rankine’s Type (see Table III.), for comparison. + Equivalent to 8 kilos. per square centimetre. ¢ Equivalent to 10 kilos. per square centimetre. The Specific Gravity of the Masonry = 2}. hy led ¥ 392 APPENDIX. TABLE IX. (See page 28.) THEORETICAL PROFILE No. 2 Joint REFERRED TO a VEr- Distance | Distance M Pp Coeffi- Depth nee i TICAL AXIS: an a pom eee cient of Factot oO: a t 2 . a a Water | Thrust | of ‘Water, een, in wace ae Hee a a pore Ronnee: Safety Foret ee | ar, | ight | cnotn, | BOR [Preomre| Bresoure oe ee 1 Feet 0 i. 5 . ‘s: = 2 6 r re _Dam, | Feet of | Masonry. | in Feet, in i eet. | in Feel, re ae oo ne i in ous ea Hse ee Equi- turn: dni Bech| Masonry in Feet. | in Feet. sonry.| lbs. sonry. Ibs. librium.| ing. 0.00 oO ©] 16.40} 0.00 | 16.40%] 0.0} 8.20 8.20 0.00] 0.00 0.0 | 0.00 | 0.00 | 0.00 37-47 301 3758 | 16.40 | 0.00 | 16.40 | 614.5] 2.09 8.20 |196.53/14.34t| 37.5 2.73 | 0.49 | 1.34 50.00 535 8929 | 21.95 | 0.00 | 21.95 | 854.8} 2.90 8.61 |196.53!14.34 | 64.1 | 4.67 | 0.63 | 1.28 60.00 771 15429 | 27.19 0.00 | 27.19 |1100.5] 3.73 9.44 |196.53/14.34 B79, 5.67 } 0.70 | 1.26 79.00] 1049 24500 | 32.89 0.00 | 32.89 |1400.9} 4.74 10.65 |196.53/14.34 87.2 6.36 | 0.75 | 1.27 80.001 1370} 36571 | 38.90 | 0.00 | 38.90 |1759.8] 5.98 12.14 1196.53|14.34 | 96.7 | 7.05 | 0.78 | 1.29 go.00| 1734 52071 | 45.14 | 0.00 | 45.14 [2180.0] 7.39 13.86 |196.53/14.34 | 104.9 | 7.65 | 0.79 | 1.31 100.00) 2141 71429 | 51.59 | 0.00 | 51.59 |2663.7/ 9-03 15.74 |196.53/14.34 | 112.9 8.23 | 0.80 | 1.33 110.00) 2591 95071 | 58.24 | 0.00 | 58.24 /3212.8] 10.90 17.75 |196 53/14.34 | 120.7 8.80 | 0.80 | 1.37 120.00] 3084 | 123429 | 65.10 | 0.00 | 65.10 |3829.5] 13.04 1g 84 |196.53/14-34 | 128.7 | 9.38 | 0.80 | 1.41 130.00] 3619 | 156929 | 72.11 0.00 | 72.11 |4515.6] 15.32 22.04 |196.53/14.34 | 136.6 | 9.96 | 0.80 | 1.44 140.00] 4197 | 196000 | 79.37 | 0.00 | 79.37 |5273.0] 17.88 24.32 |196.53]14.34 | 144.5 | 10.54 | 0.80 | 1.48 150.00) 4818 | 241071 | 86.87 | 0.00 | 86.87 |6104.2} 20.71 26.67 |196.53/14.34 | 152.6 | 11.13 | 0.79 | 1.53 160.00] 5482 | 292571 94.61 0.00 | 94.61 {7011.6} 23.78 29.10 |196.53/14.34 | 160.6 } 11.71 | 0.78 | 1.57 scac il * Equal to 5 metres. + Equivalent to 14 kilos. per square centimetre. The Specific Gravity of the Masonry = 2}. TABLE X. (See page 29.) THEORETICAL PROFILE No. 3 Joivr REFERRED TO A VER- Distance | Distance M Pp ‘ Coeffi- Depth |Horizon- CAE, ied aoa Beet eee cient of| Factor of tal Moment Total | ¢ 2 a Race to ; ae Fric- | _ of Water | Thrust | of Water, Area, in ine of | Likeof Reservoir Full. | Reservoir Empty.| tion Safety aoe erates ele Lef: Right Total =a Dressure Pressure,) _ |. . |. . 1. . ae to against opo in Cubic t eft, 1 y otal, ts i a sar or ver- bas, in| Feet of Macau, in Feet. | in Feet. | in Feet. - ra ae teh yA ea Me ee = hg in tees ‘Equi. turn: Feet. |IMasonry Feet, Heer, sonry. lbs, sonry. lbs, librium.| ing. 0.0 ° o | 18.74] 0.00 | 18.74* o| = 9-37 9-37 v.0}| 0.00 0.0 | 0.00 | 0.00 | 0.0 26.5 175 1551 18.74] 0.00 | 18.74 497 6.25 9-37 53.0] 3-31 26.5 | 1.66 0.35 | 3.0 40.0] 400 5333 25.08| 0.00 | 25.08 792 8.36 9.99 63.1] 3.94 50.8 | 3.18 O51 | 2.2 50.0 625 10417 31.17| 0.00 | 31.17 1074| 10.39 11,08 68.9) 4.31 64.4 | 4.03 0.58 | 2.1 60.0} goo 18000 | 37.92] 0.00 | 37.92 T4I19| 12.64 } 12.60 74.8] 4.68 75.1 | 4.69 | 0.63] 2.0 70.0} 1225 28583 | 45.52) 1.04 | 46.56 1842] 15.52 15.52 79-1| 4.94] 79-I | 4.94 | 0.66] 2.0 80.0) 1600 42667 52.83} 1.64 | 54.47 2347| 18.16 18.16 86.2] 5.39 86.2 | 5.39 0.68 | 2.0 go.0} 2025 60750 60.16] 2.04 | 62.20 2930] 20.73 20.73 94.2] 5.89 94.2 | 5.89 0.69 | 2.0 TOO O} 2500 83333 67.36} 2.29 | 69.65 3589] 23.22 23.22 | 103.1] 6.44 | 103.1 | 6.44 0.69 | 2.0 IIO.0] 3025 | I10g17 74.52] 2.46 | 76.98 4322} 25.66 25.06 | 112.3] 7.02 | 112.3 | 7.02 0.70 | 2.0 _120.0] 3600 | 144000 81.65} 2.58 | 84.23 5129] 28.08 28.08 | 121.8} 7.61 | 121.8 | 7.61 0.70 | 2.0 130.0] 4225 | 183083 88.77| 2.66 | 91.43 6007| 30.48 30.48 | 131.1] 8.19+] 131.1 | 8.19 0.70 | 2.0 140.0] 4900 | 228667 98.43) 3.87 |102.30 6976} 35.42 34.10 | 131.1] 8.19 | 136.4 | 8.53 0.70 | 2.1 150.0} 5625 | 281250 | 108.45] 5.00 |II3.45 8054) 40.71 37.82 | 131.1] 8.19 | 145.0 | 9.06 0.70 | 2. 160.0| 6400 | 341333 | 118.89] 6.10 /124.99 9246) 46.41 41.66 | 131.1] 8.19 | 148.0 | 9.25 0.69 | 2.3 170.0) 7225 | 409417 | 129.71; 7.17 |136.88 | 10556] 52.46 45.63 | 131.1! 8.19 | 154.2 | 9.64 0.69 | 2.4 180.0} 8100 | 486000 | 140.91} 8.23 |149.14 | 11986] 58.88 | 49.71 | 131.1] 8.19 | 160.7 |10.04 0.68 | 2.5 190.0] 9025 | 571583 | 152.67) 10.49 |163.16 | 13547] 65.85 55.12 | 131.1] 8.19 | 163.8 |ro.24t | 0.67 | 2.6 200.0} 10000 | 666667 | 164.97] 14.22 |179.19 | 15259] 73.88 61.63 | 131.1] 8.19 | 163.8 |10.24 0.65 | 2.7 s * Equivalent to 8 kilos. per square centimetre. * The top width was made equai to that of Rankine’s Type (see Table III.), for comparison. The Specific Gravity of the Masonry = 2. + Equivalent to to kilos. per square centimetre. APPENDIX. 393 TABLE XI. (See page 29.) THEORETICAL PROFILE No. 4. Josie REP RRED ED a Viet Distance | Distance Maxima PRESSURES Coeffi- Depth Hiariane- si TIGAL Us: ii on irene : vier Packt i : os : a 2 Water Thrust af Wale eee ove ee He a seseayae Pek Seon are tion nee Safety Below |ofWater,| in Cubic : Square) 5 mecca Deecare essary jagainst Top of | in Cubic] Feet of | Left, | Right, | Total, eet. Reservoir Reservoir In Feet|In Tons| In Feet | In Tons for | Over- Dam, in] Feet of | Masonry. | in Feet. | in Fect. | in Feet. Full Empt of Ma- | of 2000] of Ma- | of 2000 | Equi- | turn- Feet. |Masonry ia Feet. | in Beet sonry. Ibs. sonry. lbs. |librium.) ing. 0.00 oO oO 18.74] 0.00 |* 18.74 OQ} 9.37 9.37 0.0] 0.00 0.0 | 0.00 | 0.00! 0.0 27.58 176 1614 18.74] 0.00 18.74 517 6.25 9.37 55.3) 3-74 27.7 | 1.88 0.34} 3.0 40.60 370 4923 24.20] 0.00 24.20 784 8.07 9.84 64.8] 4.39 50.5 | 3.42 0.47 | 2.3 50.00 577 9615 29.87| 0.00 29.87| 1054 g.96 10.79 70.6) 4.78 65.0 | 4.40 | 0.55 | 2.1 60.00 831 16615 36.25} 0.00 36.25} 1385) 12.08 12.18 76.4) 5.17 975.6 | 5.12 0.60 | 2.0 JO oo} 1132 26386 43.41] 0.87 44.28) 1788) 14.76 14.76 80.7) 5.46 80.7 | 5.46 | 0.63] 2.0 80 oo] 1478 39385 50.52] 1.55 52.07} 2269) 17.36 17.36 87.2] 5.90 87.2 | 5.90 0.65 | 2.0 go.oo] 1871 56077 57-52) 1.99 59-51} 2827| 19.84 19.84 95-0] 6.43 95.0 | 6.43 0.66 | 2.0 100.00] 2309 76923 64.45] 2.27 66.72; 3458) 22.24 22.24 | 103.7] 7.02 | 103.7 | 7.02 0.66 | 2.0 TIO.00] 2795 | 102385 71.35! 2.47 73.82) q416z| 24.61 24.61 | 112.7] 7.63 | 112.7 | 7.63 0.67 | 2.0 120,00] 3326 | 132923 78.21) 2.61 80.82) 4934] 26.94 26.94 | 121.0] 8.19t/ 122.1 | 8.26 | 0.67 | 2.0 130.00] 3903 | 169000 87.68] 3.87 91.55} §796| 31.84 30.52 | 121.0] 8.19 | 126.6 | 8.57 | 0.67 | 2.1 140.00] 4527 | 210769 97-30] 4-94 | 102.24) 6765] 37.00 34.08 | 121.0] 8.19 | 132.3 | 8.96 | 0.67} 2.2 150.00} 5196 | 259615 | 107.44] 6.02 | 113.46) 7844) 42.54 37.82 | 121.0) 8.19 | 138.3 | 9-36 | 0.66 | 2.3 169.00] 5912 | 315077 | 117.94] 7.05 | 124.99] 9036] 48.46 41.66 | 121.0] 8.19 | 144.6 | 9-79 | 0.65 | 2.4 170 00} 6674 | 377692 | 128.81) 8.05 | 136.86] 10345] 54.73 45.62 | 121.0] 8.19 | 151.2 |10.24f | 0.64 | 2.5 180 oo} 7483 | 448615 | 140.47] 11.30 | 151.77] 11788] 61.77 51.94 | 121.0] 8.19 | I51.2 |10.24 0.63 | 2.6 190.00} 8337 | 527615 | 152.60] 15.09 | 167.69] 13386} 69.44 58.83 | 121.0} 8.19 | 151.2 |10.24 | 0.62 | 2.7 200,00] 9238 | 615385 | 165.24) 19.47 | 184.71] 15148] 77.72 66.36 | 121.0] 8.19 | I5I.z |10.24 | 0.61 | z.9 * + Equivalent The top width was made equal to that of Rankine’s Type (see Table III.), for comparison. to 8 kilos. per square centimetre. ¢ Equivalent to 10 kilos. per square centimetre. The Specific Gravity of the Masonry = 23. TABLE XII. (See page 29.) THEORETICAL PROFILE NO. 5. Depth |Horizon- ce ees > rae Dips Maxima Pressures. Coeffi- | 5 of tal Moment Front Back cient ae Water | Thrust | of Water Total | Face to] Face to| Reservoir Reservoir |0f Fric-| catety Below of in Cubic’ Area, in | rine of | Line of Full. Empty. tion | against = of ue Feet of Left, | Right,| Total, a era Pressure, | Pressure, | ————————- ey ver- am Feet se Masonry. | in Feet. jin Feet.| in Feet. te Reservoir) Reservoir|In Feet In Tons|In Feet) In Tons os turn- Feet, {Masonry Meee | Page mL aca (at gone eb Mae) of eee htealute,| 3 0.00 oO o | 18.74 | 0.00 |* 18.74 ° 9.37 9-37 | 0.0} 0.00 | 0.0] 0.00 | 0.00 |] o.o 28.62 175 1671 | 18.74 | 0.00 18.74 536 6.25 9-37 | 57.2 | 4.17 | 28.6 | 2.09 0.33 3.0 40.00) 343 4571 | 23.45 | 0.00 23.45 776 7.82 9-74 | 66.2 | 4.83 | 49.7 | 3.62 v.44 2.3 50.00 535 8929 | 28.78 | 0.00 28.78} 1038 9-59 10.58 | 72.2 | 5.26 | 65.0 | 4.74 | 0.52 2.1 60.00) 771 15429 | 34.83 | 0.00 34.83! 1356 I1.61 11.83 | 77.8 | 5.67 | 76.2 | 5.56 0.57 2.0 70.00] 1049 24500 | 41.37 | 0.85 42.22) I741 T4s07 14.07 | 82.5 | 6.01 | 82.5 | 6.01 0.60 20 80.00] 1370 36571 | 48.28 | 1.60 | 49.88] 2206 16.63 16.63 | 88.4 | 6.45 | 88.4 | 6.45 0.62 2.0 go.00] 1734 52071 | 54.97 | 2.04 57.01) 2740 19.00 19.00 | 96.2 | 7.01 | 96.2 | 7.07 0.63 2.0 100.00] 2I4r 71429 | 61.68 | 2.38 64.06, 3345 21.35 21.35 |104.4 | 7.61 |104.4 | 7.61 0.64 2.0 I10.00} 2591 95071 | 68.34 | 2.60 70.94) 4020 | 23.65 23.65 |112.3 | 8.19tit12.3 | 8.19 | 0.64 2.0 120.00} 3084 | 123429 | 77.39 | 3.82 81.21) 4781 28.32 27.07 |112.3 | 8.19 {117.8 | 8.59 | 0.64 2.1 130.00} 3619 | 156929 | 86.68 | 4.88 gI.56) 5645 $3.22 30.52 |112.3 | 8.19 |123.3 | 8.99 0.64 2.2 140.00] 4197 | 196000 | 96.43 | 5-90 | 102.33] 6615 38.59 34-II |112.3 | 8.19 |129.3 | 9.43 0.63 253 150.00}; 4818 | 241071 |106.60 | 6.90 |} 113.50 7694 44.34 37.83 [112.3 | 8.19 |135.6 9.89 0.63 24 160.00] 5482 | 292571 |117.15 | 7.87 12502) 8886 50.43 41.67 |112.3 | 8.19 |140.4 |10.24¢| 0.62 25 170.00} 6188 | 350929 |128.57 {11.67 | 140.24! 10213 57.45 48.43 |112.3 | 8.19 |140.4 |10.24 @.6T 2.6 180.00] 6938 | 416571 |}140.50 |15.46 | 155.96 11694 65.05 55.28 |112.3 | 8.19 |140.4 |10.24 0.59 2.8 190.00] 7730 | 489929 |152.91 |19.95 | 172.86) 13338 73.26 62.87 |112.3 | 8.19 j140.4 j10.24 | 0.58 3.0 200.00} 8565 | 571429 |165.96 [25.02 | 190.98) 15157 | 82.29 | 70.99 |112.3 | 8.19 |140.4 |t0.24 | 0.56 | 3.2 * The top width was made equal to that of Rankine’s Type (see Table III.), for comparison. + Equivalent to 8 kilos, per square centimetre. ¢ Equivalent to ro kilos. per square centimetre, The Specific Gravity of the Masonry = 2}. APPENDIX. TABLE XIII. (See page 29.) THEORETICAL PROFILE NO. 6, Depth Hot Shige eksenee ne D uae Diane Maxima Pressures. en Factor en Wailer Thrust Moment Total Front Back ‘ R i et nies of Below ot of Water, Area in| Face to | Face to Reservoir eservoir tion | Safety Top of | Water, | 2 Cubic : Square | Line of | Line of Full. Empty. neces- | 282inst Dam. (ia Cubic Feet of : Left, Right, Total, cee Pressure, Pressure, Een GR aEEs sary for ver- ey eee Masonry. | in Feet. /in Feet.| in Feet. Reservar peer year ie pee in Tone in tet ty Meas Equi- oe Feet. |Masonry Beek. Oyeet. 7 unn “he sonry. Ibs. librium. 0.0 ° o | 18.74 | 0.00} 18.74 ° 9.37 9:37 | 0.0] 0.00 | 0.0 | 0.00 | 0.00 | 0.0 29.6 175 1729 | 18.74 | 0.00] 18.74 555 6.25 9-37 | 59.2 | 4.63 | 29.6 | 2.31 0.32 3.0 40.0 320 4267 | 22.80 0.00] 22.80 wt 7.60 9.66 | 67.6 | 5.28 | 49.3 | 3-85 0.41 2.4 50.0 500 8333 | 27.85 0.00] 27.85 1024 9.28 10.42 | 73.5 | 5.74 | 64.6 | 5.04 0.49 212 60.0 720 14400 | 33.58 | 0.00] 33.58 1331 I1.19 11.57 | 79-3 | 6.19 | 76-6 |} 5.99 | 0.54] 2.0 70.0 g80 | 22867 | 39.91 | 0.39] 40.30 1701 13.43 | 13-43 : 84.4 | 6.59 | 84.4 | 6.59 | 0.58] 2.0 80.0 1280 34133 | 46.62 1.20] 47.82 2141 15.94 15.94 | 89.5 | 6.99 | 89.5 | 6.99 0.59 2.0 g0.0 1620 | 48600 | 53.20 1.72] 54.92 2655 18.31 18.31 | 96.7 | 7.55 | 96.7 | 7.55 | 0-61 2.0 100.0 2000 66667 | 59.69 2.07] 61.76 3238 20.59 20.59 |104.9 | 8.19*|104.9 | 8.19 0.62 2:0: 10.0 | 2420 | 88733 | 68.08 | 3.16) 71.24 3903 | 24.76 | 23.75 |104.9 | 8.19 |109.6 | 8.56 | 0.62] 2.1 120.0 2880 | 115200 | 78.97 4.20] 81.17 4665 29.42 27.06 |104.9 | 8.19 |115.0 | 8.98 0.62 2.2 130.0 3380 | 146467 | 86.32 5.21! gl.53 5529 24.53 30.51 |104.9 | 8.19 |120.8 | 9.44 | 0.61 2.3 140.0 | 3920 | 182933 | 96.10 | 6.19)102.29 6498 | 40.03 34.10 |104.9 | 8.19 |127-1 | 9-93 | 0-60] 2.4 150.0 4500 | 225000 |106.40 7. 89/114.29 7581 46.06 38.55 |104.9 | 8.19 |131.1 |10.24 +] 0.59 2.6 160.0 5120 | 273066 |117.39 | I1.15}128.54 8796 52.84 | 44.65 |104.9 | 8.19 |131.1 j10.24 0.58 2.7 170.0 5780 | 327533 |128.93 | 15.00]143.93 | 10158 60.30 51.39 |104.9 | 8.19 |131.1 10.24 | 0.57 2.9 180.0 6480 | 388800 ]141.06 | 19.49|160.55 11680 68.45 58.81 j104.9 | 8.19 |131.1 |10.24 0.56 3x1 190.0 7220 | 457286 |153.82 | 24.66|178.48 | 13375 77.35 66 g4 |104.9 | 8.19 |131.1 |10.24 0.54 3.3 200.0 8000 | 533333 |167.25 | 30.57)197.82 | 15257 87.03 75.83 |104.9 | 8.19 |131.1 |10.24 0.52 3.5 The Specific Gravity of the Masonry = 2}. * Equivalent to 8 kilcs. per square centimetre, + Equivalent to 70 kilos. per square centimetre. APPENDIX. 395 TABLE XIV. (See page 31.) INCLINED JOINTS IN THEORETICAL PROFILE No, 5. Depth of Horizontal Moment Joint. Distance Maxims, PRSSEEEE Coeffi- ater of one of Water, |————~——_——_——|_ Angle _| Total Area, ee Reservoir Full. Eleat ot Below Top| %. Cabic | in Cubic | Below Top of Dam. with the | in Square |4f Pressure, |) 1. 7... | necessary a aie Feet of Pecces Front Back Length. Horizon. Feet. Reservoir |In Feet of ta Tene for Equi- 7 Masonry. ral Edge. Edge. Full, in Feet.) Masonry. Ibs, librium. 28.62 175 1671 18.62 | 28.62 | 21.23 | 28° 05' 442.64 9-55 28.97 | 2.11 O.II 28.62 175 1671 23.62 | 28.62 19.38 | 14° 56’ 489.49 7.59 44.21 | 3.22 | 0.08 28 62 175 1671 28.62 28.62 18.74 oO 536.34 6.25 57.20 4-17 0.33 28 62 175 1671 33.62 28.62 21.37 | 13° 32) 583 20 7.49 46.75 3.41 0.58 28.62 175 1671 40.00 28.62 26.04 | 25° 53' 642.96 g.00 32.42 2.36 0.87 60,00 771 15429 45.00 | 60.00} 30.12 | 29° 53’ 1096.18 10.48 84.72 | 6.18 0.10 60,00 771 15429 47.50 60.00 30.19 | 24° 29' 1138.79 10.27 88.04 6.42 0.17 60,00 771 15429 50.00 60.00 30.50 | Ig° 10° 1181.36 10.17 89.77 6.55 0.25 60,00 771 15429 52.50 60.00 31.12 | 13° 55° 1224.89 10.31 88.94 6.49 0.33 60,00 771 15429 55.00} 60.00 | 32.20] 8° 56’ 1268.45 10.68 85.76 | 6.26 | 0.41 60.00 771 15429 60.00 60.00 34.83 oO 1355.70 11.61 77.80 5.67 0.57 60.00 771 15429 65.00 | 60.00 | 38.46 7° 29) 1437-59 13.14 67.18 | 4.90 | 0.72 60,00 771 15429 70.00 | 60.00 | 42.55 | 13° 35" 1519.67 15.08 57.10 | 4.17 0.85 60,00 771 15429 75.00 60.00 47.31 | 18° 30, 1605.80 17.44 48.37 3.53 0.97 II0,00 2591 95071 85.00 | 110.00 59.67 | 24° 45 3133.69 20.78 125.80 g.18 0.40 110.00 2591 g507L 87.50 | 110.00 | 60.16 | 21° 56’ 3222.52 20.68 127.66 | 9.32 0.30 110,00 2591 95071 go.00 | 110.00 | 60.98 | 19° Io’ 3311.35 20.85 126.99 | 9.27 0.34 I10,00 2591 95071 g5.00 | 110.00 62.76 | 13° 50' 3488.53 21.16 126.37 g.22 0.42 IIO,00 2591 95071 100.00 | 110.00 64.98 8° 51’ 3665.71 21.69 123.83 9-04 0.49 110,00 2591 95071 110.00 | 110.00 70.94 oO 4020.40 23.65 113.40 8.28 0.64 II0.00 2591 95071 115.00 | II0.00 75.63 3° 48' 4197.76 26.25 101.93 7-44 0.71 110.00 2591 g5071 120.00 | II0.00 80.64 7° 08" 4375-12 28.91 92.32 6.74 0.77 110,00 2591 95071 125.00 | I10.00 86.70 9° 59. 4553.71 32.68 80.98 5.91 0.83 160.00 5482 292571 I10.00 | 160.00 g1.08 | 33° 16’ 5815.18 32.99 157.75 | 11.51 0.18 160,00 5482 292571 115.00 | 160.00 92.40 | 29° 08’ 6118.39 33.35 158.93 | 11.60 0.23 160,00 5482 292571 120.00 | 160.00 94.12 | 25° 08' | 6421.60 33.96 158.68 | 11.58 0.27 160.00 5482 292571 125.00 | 160.00 96.42 | 21° 16 6727.60 34-93 156.68 | 11.44 0.32 160,00 5482 292571 130.00 | 160.00 99.33 | 17° 36’ 7033.60 36.30 152.21 | 11.11 0.37 160.00 5482 292571 135.00 | 160.00 | 102.46 14° 07’ 7337.11 37.97 147.68 | 10.97 O 42 160.00 5482 292571 140.00 | 160.00 | 105.82 | 10° 52’ 7640.62 39.50 I42.10 | 10.37 0.46 160.00 5482 292571 145.00 | 160.00 | 110.29 7° 48 7950.97 41.95 134.55 | 9.82 0.50 160.00 5482 292571 150.00 | 160.00 | IT4.94 5° 00 8261.32 44.55 126.81 9.26 0.54 160.00 5482 292571 155.00 | 160.00 | 119.85 2° 24' 8573.86 47.39 | 119.50] 8.72 0.58 160.00 5482 292571 160.00 | 160.00 | 125.02 ° 8886.30 50.43 112.30 8.20 0.62 160.00 5482 292571 165.00 | 160.00 | 131.58 2. 11! g1y8.94 54.60 103.10 7:52 0.65 160.00 5482 292571 170.00 | 160.00 | 137.00 | 4° 12’ gs1r.48 58.03 96.80 | 7.06 | 0.68 160.00 5482 292571 175.00 | 160.00 | 142.86 6° o1' 9823.18 61.85 g0.09 6.57 0.71 160.00 5482 292571 200.00 | 160.00 | 178.57 | 12° 58’ | 11337.30 86.01 61.19 4.47 0.80 TABLE XV. (See page 31.) THEORETICAL PROFILE NO. 5, MODIFIED BY BOUVIER’S FORMUL&, Depth [orion ee Distance | Distance] Maxina Pressures | Coeth-| recto Water | Thrust ne Total wnt. Fotos Reservoir Reservoir of Fric-| .,° Below | of | lin Cubic Area, in | Tine of | Line of Full. Empty. ven | Seer Tet by oreray Feet of | Left, | Right, Total, sre Pressure, | Pressure, ered ‘Over: in’ | Feet of Masonry.| in Feet. Jin Feet.} in Feet. * |Reservoir |Reservoir an Ny In TonsiIn Feet] In Tons Eau turn- Feet. |Masonry Hl [rapa na Mee et gore | ae a | of 2268 scbam,| 28 100 2141 71429] 62.75] 2.84! 65.59] 3353-00] 22.43 21.86 |140.26) 16.23/102.24] 7.46 | 0.64 | 2.05 110 | 2591 g5071| 71.71} 3.95} 75.66) 4058.25] 27.00 25.24 140.31) 10.24/107.28] 7.83 | 0.64 | 2.15 120 | 3084 | 123429} 81.04] 4.95] 85.99] 4866.50) 31.95 28.68 |140.43} 10.25/113.19] 8.26 | 0.63 | 2.20. 130 | 3619 | 156929) 90.76] 5.88) 96.64) 5779.65} 37.31 32.23 j140.10] 10.22/119.61| 8.73 | 0.63 | 2.38 140 4197 | 196000] 100.79] 6.75] 107.54] 6800.55] 42.86 35.86 |140.50| 10.25/126.48| 9.23 | 0.62 | 2.50 150 | 4818 | 241071} 111.18} 7.59} 118.77] 7932.10} 48.78 39.60 |140. 48) 10.25/133.57/ 9.75 | 0.61 | 2.60 160 5482 | 292571) 121.89] 8.56) 130.45] 9178.20] 54.98 43-59 |140.51| 10.25/140.44| 10.25 | 0.60 | 2.72 170 6188 | 350929} 133.45] I1.95| 145-40,10557 45 62.09 50.07 |140.36] 10.24 140.43] 10.25 | 0.59 | 2.87 180 | 6938 | 416571] 145.36) 15.94 161 .30,12090 95} 69.65 57-19 |140.55 10. 26/140. 33 10.24 | 0.57 | 3.02 190 7730 | 489929] 157.74] 20.53) 178.2713788.80] 77.83 64.91 |140.39 10. 25/140.47 10.25 | 0.56 | 3.19 200 8565 | 571429] 170.56] 25.79 ghee geMt 9 86.57 73.30 |140.32 10,24) 4038 10.25 | 0.55 | 3.37 396 APPENDIX. TABLE XVI. (See page 36.) THEORETICAL TYPE No. I. : Distance from Maxima Pressures d epth of | Horizontal entre of Joint : 3 Coefficient | Factor ® ater ‘Thrust of mere ae Length of | Total Area, . to roe Reservoir Full or Empty. of Friction ey Se cere) eat | ee, Vent ae en pace lace ne : ’ a F a P . In Feet of | In Tonsof |; 4 S ielect. bat Masonry, Masonry or Ems, in Naseary, zooo Ibs, |Equilibrium.| ing. ° ° 0.0 0.00 00.0 0.00 ° 0.00 0.000 ° 10 21 7I.4 6.55 32.7 1.09 10 0.73 0.655 2 20 84 571-4 13-09 130.9 2.18 20 1.46 0.655 22 30 193 1928.0 19.64 294.6 3.27 30 2.19 0.655 2 4o 343 4571-4 26.19 523.7 4.36 40 2.92 0.655 2 50 535 8928 6 32.73 818.3 _ 5.45 50 3.65 0.655 2 60 771 15428.6 39.28 1178.4 6.55 60 4.38 0.655 2 70 1049 24500.0 45.83 1603.9 7.64 70 5.11 0.655 2 80 1370 36571.4 52.37 2094 9 8.73 80 5.84 0.655 2 go 1734 52071.4 58.92 2651.4 9.82 go 6.57 0.655 2 100 2141 71.428 .6 65.47 9273.3 10.91 100 7.30 0.655 2 110 2591 g4071.4 72.01 3960.7 I2.00 I10 8.03 0.655 2 I20 3084 I23428.6 78.56 4713.5 13.09 120 8.76 0.655 2 130 3619 156928 .6 85.11 5531.9 I4.18 130 9-49 0.655 2 140 4197 196000.0 gt.65 6415.6 15.27 140 10.22 0.655 2 150 4818 241071. 4 98.20 7364.9 16.37 150 10.95 0.655 2 160 5482 292571.4 104.75 8379.7 17.46 160 11.68 0.655 2 170 6188 350928 .6 III.29 9459.8 18.55 I70 I2.41 0.655 2 180 6938 416571.4 117.84 10605 .5 Ig.64 18G 13.14 0.655 2) Ig0 7730 489928 .6 124.39 1816.6 20.73 Igo 13.87 Oo 655 2 200 8565, 571428.6 130.93 13093.2 21.82 200 14.60 0.655 2 The Specific Gravity of the Masonry = 24. TABLE XVII. (See page 38.) PRACTICAL TYPE No, I. Seis er eiee Ae & EE Distance! Distance Maxima Pressures. Coeffi- Depth |Horizon- ha ss IER NIS te | am ae : cient of| Factor of tal Moment Total root ac : = Fric- of Water | Thrust | of Water, Aveacin veer 8 ree ig Reservoir Full. | Reservoir Empty.| tion Safety Slee ae rniets ipisubie an Ras ae mquere Peessire. Pressure, aa against am,in Feet of | Masonry. | in Feet. | in Feet. | in Feet. rc pee fp eerrals ey te ee a ‘i ig oes qui furh- Feet. | Masonry pees a Sonry.| ‘bs.. | soory: Ibs, |librium.) ing. 0.00 o}] ‘ 0.0} 20.00} 0.00] 20.00 0.0} 10.00 10.00 0.0} 0.00] 0.0] 0.00] 0.00 | 0.0 10.00 21 71.4| 20.00) 0.00 | 20.00) 200.0] 9.64 10.00 | 11.1] 0.81| 10.0] 0.73 | 0.11 | 27.8 20.00) 84 571.4] 20.00} 0.00 20.00} 400.0] 8.57 10.00 28.6] 2.09] 20.0 1.46 | 0.21 | 7.0 30.55 200 2036.6; 20.00! 0.00 20.00) 611.0; 6.67 10.00 61.1) 4.46) 30.6 2.23 | 0.33 | 2.0 40.00) 343 4571.4) 26.19] 0.00 26.19} 829.2] 10.25 10.42 52.3) 3.82] 51.0 3.72 | O.41 | 29 50.00] 535 8928.6) 32.73) 0.00 | 32.73) 1123.8] 13.61 1i.57 51.6] 3.77| 64.5 4.71 | 0.47 | 2.8 60.00 771 | 15428.6| 39.28] 0.00 39-28] 1483.9] 15.74 13.14 60.2) 4.39] 75.2 5.49 | 0.52 | 2.5 70.00, 1049 | 24500.0) 45.83) 0.00] 45.83) 1909.4] 18.04 14.96 68.2! 4.98) 85.1 6.21 | 0.55 | 2.4 80.00] 1370 | 36571.4) 52-37] 0.00 52.37| 2400.4] 20.21 16.93 77.3) 5.641 94.5 6.90 | 0.57 | 2.3 go.00| 1734 | 52071.4/ 58.92] 0.00 | 58.92] 2956.9] 22.32 18.99 | 86.6} 6.32! 103.8 | 7.58 | 0.59] 2.3 Too CO. 2I4t | 71428.6) 65.47; 0.00 65.47) 3578.8) 24.41 21.09 96.4; 7.04) 113.1 8.25 | 0.60 | 2.2 II0.00) 2591 | 94071.4| 72.01%) 0.00 72.01) 4266 2) 26.48 23.24 | 106.3) 7.76) 122.4 8.94 | 0.61 | 2.2 120.00, 3084 |123428.6) 78.56; 0.00 | 78.56 5org.1| 28.57 | 25.40 | 116.1] 8.48 131.7 | 9.61 | 0.61 | 2.1 130.00, 3619 |156928.6| 85.11] 0.00 85.11} 5837.4] 30.65 27.58 | 126.2) g.21! I41.I |] 10.30 | 0.62 | 2.1 140.00, 4197 1g6000.0} 91.65} 0.00 gr -68, 6721.2) 32.72 29.977 | 146.2 9-94) 150-5 I0.98 | 0.602 | 2.1 150.00, 4818 |241071.4] 98.20} 0.00 98.20 7670.4) 34.72 31.96 | 146.8] 10.72 160.0} 11.68 | 0.63 | 2.1 160.00) 5482 |292571.4| 104.75] 0.00 104.75, 8685.1] 36.90 34.16 | 156.3] 11.41; 169.5 | 12.37 | 0.63 | 2.1 170.00, 6188 |350928.6] TII.29] 0.00 III.29 9765.3) 39-00 36.35 | 166.5] 12.15 179.1 | 13.07 | 0.63 | 2.1 180.00, 6938 |416571.4] 117.84] 0.00 | 117.84 Iogtr.o| 41.10 | 38.55 | 176.7 12.90| 188.7 | 13.76 | 0.63 | 2.1 190.00, 7730 489928 .6) 124.39] 0.00 | 124.39 12122.1) 43.22 40.75 | 186.7] 13.63) 198.3 | 14.46 | 0.64 | 2.1 | 8565 |571428.6! 130.93] 0.00 130.93,13398-7 45-33 42.95 | 196.6] 14.35] 207.9 | 15.16 | 0.64] 2.1 The Specific Gravity of the Masonry = 2}. Notr.—The Profile given by this Table can be changed to another having any desired top width (equal to #y the height) by simply changing the scale to which it has been drawn. To obtain a corresponding Table-from the one above, proceed as follows: Let 7 = ratio of desired top width to that of Practical Type No. I. Divide the numbers in columns 1, 4, 5, 6, 8, 9, 10, 11, 12, 13, by 7; those in column 2 and 7 by 7; those in column 3 by »%. ‘The numbers in column 14 and 15 will remain unchanged. APPENDIX. 397 TABLE XVIII. (See page 38.) THEORETICAL TYPE No. IL, Jowr REFERRED BO Distance | Distance AXIMA PRESSURES, oeffi- Depth | Horizon- - eee re Bak ee ee! x scent Factor z 7 ji : of Fric- Wace meas of Water: roses es ree He Resenpor Sul, Becerra SE tion nec- Sateuy Below of Water,| in Cubic . Square Pressure. | Pressure essary jagainst Top of | in Cubic) Feet of | Left, | Right, | Total, eet, Reservoir) Reservoir i Feet|In Tons} In Feet| In Tons| for | Over- Dim, in’ Feet of | Masonry. | in Feet. jin Feet.\in Feet. Pall F Empty of Ma- | of 2000] of Ma- | of 2000 | Equi- | turn- Feet. |Masonry in Feet. | in Feet. | S°MTY- lbs. sonry. Ibs. librium.) ing. 0.00 ° 0.0; 20.00] 0.00 | 20.00 0.0} 10.00 10.00 0.0 0.00} 0.0]! 0.00] 0.00} 0.0 30.55 200 2036.6) 20.00] 0.00 | 20.00 611.0 6.67 10.00 61.1; 4.45] 30.5 2523. | 0.33, 2.4 40.00 343, 4571.4) 23.75] 0.00 | 23.75 817.7 7.92 10.24 68.8} 5.02) 48.6 3.54 | 0.42 2.2 50.00 535 8928.6] 48.83) 0.00 | 28.83) 1080.6] 9.61 10.96 74.9! 5.46) 64.4] 4.70 | 0.49 2.1 60.00 771 | 15428.6) 34.68! 0.00 | 34.68) 1398.2] 11.56 12.09 80.6; 5.88) 76.9 5.61 | 0.55 2.0 67.00 962 | 21483.1) 39.08] 0.00 | 39.08} 1656.3) 13.03 13.08 84.7) 6.17) 84.6 6.17 | 0.60 2.0 80.00] 1370 | 36571.4] 48.07] 1.13 | 49.20) 2230.2) 16.40 16.40 g0.6| 6.60] 90.6 6.60 | 0.61 2.0 g0.00| 1734 | 52071.4} 54.90] 1.72 | 56.62) 2759.3) 18.87 18.87 97.4, 7.10] 97.4 7.10 | 0,62 2.0 100.00) 214I | 71428.6) 61.63} 2.12 | 63.75) 3361.1) 21.25 21.25 | 105.4) 7.68) 105.4 7.68 | 0.64 2.0 II0.00; 2591 } 95071.4| 68.31] 2.40 | 70.71) 4033.4! 23.57 23.57 | 114.1] 8.32] 114.1 8.32 | 0.64 2.0 120.00] 3084 |123428.6; 74.95] 2.60 | 77.55] 4774-7| 25.85 25.85 | 123.1} 8.97] 123.1 8.97 | 0.64 2.0 130.00) 361g {156928.6) 81.57] 2.74 | 84.31] 5584.0) 28.10 28.10 | 132.5| 9.66] 132.5 9.66 | 0.65 2.0 140.00, 4197 |Ig6000.0] 88.17] 2.84 | g1.o1| 6460.6} 30.34 30.34 | 142.0 10.35] 142.0 | 10.35 | 0.65 2.0 150.00] 4818 /241071.4| 94.76] 2.92 | 97.68) 7404.1] 32.56 32.56 151.6) TI.05} 151.6 | 11.05 | 0.65 2.0 160.00] 5482 /292571.4| 101.33] 2.98 |104.31| 8414.0] 34.77 34.77 | 161.3, 11.76) 161.3 | 11.76 | 0.65 2.0 170.00) 6188 |350928.6] 107.90] 3.03 |110.93| 9490.2] 36.98 36.98 | 171.1] 12.47] 171.1 | 12.47 | 0.65 2.0 180.00, 6938 |416571.4| 114.47] 3.07 |II7.54) 10632.6] 39.18 39.18 | 180.9] 13.19] 180.9 | 13.19 | 0.65 2.0 Ig0.00! 7730 |489928.6) 121.03] 3.10 |/124.13} I11840.9| 41.38 41.38 | 190.8] 13.91] 190.8 | 13.91 | 0.65 2.0 200.00] 8565 [571428.6| 127.59] 3.12 |130.71) 13115.1| 43.57 43-57 | 200.7] 14.63] 200.7 | 14.63 | 0.65 2.0 The Specific Gravity of the Masonry = 2}. Notr.—The Profile given by this Table can be changed to another having any desired top width (equal to +, the height) by simply changing the scale to which it has been drawn. To obtain a corresponding Table from the one above, proceed as follows: Let x = ratio of desired top width to that of Theoretical Type No. II. Divide the numbers in columns I, 4, 5, 6, 8, 9, 10, II, 12, 13 by 7; those in columns 2 and 7 by 7”; those in column 3 by 7*. The numbers in columns 14 and 15 will remain unchanged. TABLE XIX. (See page 39.) PRACTICAL TYPE No. 2. fae Rete is Digianee i Maxima Pressures. Coeffi- Depth |Horizon- Front Back © |_—-——————__________I cient of | Factor of tal Moment Total Face'te | ‘Face to Reservoir Reservoir _Fric- of Water | Thrust | of Water, -Area,in | Tine of | Line of Full, Empty. tion nec-| Safety Below fefveater.| im CuBle| are | reigns, | Total, | Hae [Pressure] Presaure, reas Dats, Feet of | Masonry. |in Feet.| in Feet. in Feet. 3 Reservoir cig tf eat In Tons e ce ines Equi: turn dn Feet. | Masonry in Feet. | in Feet. | sonry.| Ibs. sonry, lbs, |ibrium.| ing, 0.000 ° . © | 20.00] 0.00 | 20.00) 0.0) 10.00 10,00 0.0] 0.00; 0.0] 0.00 | 0.00 ' 0.0 18.744 75 470 | 20.00] 0.00 | 20.00] 374.9] 8.74 10.00 25.8) 1.89) 18.7 1.36 | 0.20 | 8.0 ‘30.000 192 1929 | 21.07} 0.00 | 21.07] 604.0) 7.86 10.06 50.41 3-63} 32.5 | 2.37 | 0.31 | 3.4 40.000 343 4571 | 23.89] 0.00 | 23.89] 827.2! 7.99 10.37 68.9} 5-03) 48.3] 3.53 | o.41 | 2.4 51.967 579 10024 | 30.04! 0.00 | 30.04] 1146.5) 10.07 Il.21 75.8) 5.53) 67.3 4.91 | 0.50 | 2.1 60.000 771 15429 | 35.38] 0.00 | 35.38! 1409.1] 12.26 I2.17 76.6) 5.59| 77.1 5.63 | 0.54 | 2.1 70.000} 1049 24500 | 42.03] 0.62 | 42.65) 1799.3! 14.71 14.33 81.4) 5-94] 83.7 6.11 | 0.58 | 2.1 80.000] 1370} 36571 | 48.68} 1.25 | 49.93) 2262.2) 17.07 16.70 88.3) 6.45] 90.3 | 6.59] 0.61 | 2.1 go.000] 1734 52071 | 55.33] 1.87 | 57.20] 2797.9] 19.39 19.20 96.1) 7.02) 97.1 7.09 | 0.62 | 2.0 100.000] 2I4I 71429 | 61.98] 2.50 | 64.48) 3406.2] 21.73 21.78 | 104.4) 7.62! 104.2 7.61 | 0.63 | 2.0 110.000] 2591 g5071 | 68.63) 3.12 | 71.75} 4087.4] 24.09 24.40 | 113.2} 8.26] 111.7 8.15 | 0.63 | 2.0 120.000] 3084 | 123429 | 75.28] 3.74 | 79.02! 4840.7| 26.46 27.06 | 121.9] 8.90) 119.1 8.69 | 0.63 | 2.0 130.000] 3619 | 156929 | 81.93} 3.74 | 85.67] 5664.2] 28.85 29.1I | 130.9] 9.55) 129.6 9-46 | 0.64 | 2.0 140.000} 4197 | 196000 | 88.58! 3.74 | 92.32] 6554.2] 31.22 31.20 | 140.0] 10.22) 140.0 | 10.22 | 0.64 | 2.0 150.000] 4818 | 241071 | 95.23) 3.74 | 98.97! 7510.7! 33.56 33.32 | 149.2 To. 89! 150.3 | 10.96 | 0.64 | 2.0 160.000) 5482 | 292571 /101.88] 3.74 |105.62| 8533.7] 35.87 35-46 | 158.5] 11.56) 160.5 | t1.71 | 0.64 | 2.0 170.000] 6188 | 350929 |108.53) 3.74 |112.27| 9623.2] 38.20 | 37.61 | 168.0) 12.25 170.5 | 12.44 | 0.64 | 2.0 180.000] 6938 | 416571 |115.18} 3.74 /118.92/10779.2| 40 50 39.78 | 177-5] 12.95] 180.7 | 13.18 | 0.64 | 20 190.000] 7730 | 489929 |121.83! 3.74 |125.57|12001.7| 42.80 41.95 186.9) 13.63} 190.7 | 13.91 | 0.64 | 2.0 200.000) 8565 | 571429 /128.48| 3.74 |132.22/13290.6] 45.10 | 44.13 | 196.4] 14.32) 200.8 14.65 | 0.64 | 2.0 The Specific Gravity of the Masonry = 2}, NoTtE.—The Profile given by this Table can be changed to another having any desired top width (equal to ,), the height) by simply changing the scale to which it has been drawn. To obtain a corresponding Table from the one ahove proceed as follows: Let y = ratio of desired top width to that of Practical Type No. 2. Divide the numbers in columns I, 4. 5, 6, 8, 9, 10. 11, 12, 13. by 7; those in columns 2 and 7 by 7*; those in column 3 by *. The numbers in columns 14 and 15 wiil remain unchanged. 398 APPENDIX. TABLE XX. (See page 41.) PRACTICAL PROFILE No. 1. REFE D TO A VER- Dist: Dist Depth Horizon- Joint eee R from from Maxima Pressures. ae, mee W: tal M T 1 ron aC. 7m Z Fric- f Below AYU | of Water, Areayin] Face 69] Face re | Reh” | Smpty., _ [onnec| Safety weet in Cubic a adie Left, Right, | Total, Square Pressure,) Pressure, See 4) inet ia” Bad of Masonry in Feet. | in Feet. | in Feet. R Batervoln oe ie re Tn rans is oe To Equi- | turn: " ull, in mpty, | 0 - 2000 - : 5 Bese, |e Feet. | in eet, sonry.|{ Ibs. | sonry. Ibs, [Hibrium.| ing. 0.000 ° ° 5.00 0.900 5.00] 0.0} 2.50 2.50 0.00} 0.00 | 0.00 | 0.00 | 0.00 | 0.0 4-686 5 9% 5.00 0.00 5.00] 23.4] 2.18 2.50 6.45] 0.48 4-70 | 0.34 | 0.20] 8.0 10.000] 22 71 5.98 0.00 5.98] 51.7] 2.00 2.60 | 17.25/ 1.26 | 12.10 | 0.89 | 0.41 | 2.4 12.992 36 157 7.51 0.00 750] PRaz) 2.52 2.81 | 18.95] 1.39 | 16.85 1.23 |] 0.50] 2.1 15.000 48 241 8.85 0.00 8.85} 88.1] 3.07 3.05 Ig.15] 1.40 | 19.30 7.40 | O.54 | 2.5 20.000 86 571 12.17 0.32 | 12.49] I41.4] 4.27 4.18 | 22.10) 1.62 | 22.60 1.65 | 0.61 | 2.1 25.000] 134 T116 15.50 0.62 | 16.12) 212.9] 5.44 5.45 | 26.10] 1.92 | 26.05 I.90 | 0.63 | 2.0 30.000] 193 1929 18.82 0.94 | 19.76) 302.6] 6.62 6.77 | 30.50] 2.23 | 29.80 2.18 | 0.63 | 2.0 35.000] 262 3063 22.14 0.94 | 23.08] 409.7) 7.81 7.80 | 35.00) 2.51 | 35.00 2.55 | 0.64 | 2.0 40.000] 343 4571 | 25.47 0.94 | 26.41] 533.4) 8.97 8.87 | 39.65] 2.39 | 40.15 2.93 | 0.64 | 2.0 45-000] 434 6509 28.80 0.94 | 29.74) 673.7| 10.13 9-95 | 44.40] 3.24 | 45.20 3.30 | 0.64 | 2.0 50.009] 535 8929 | 32.12 0.94. | 33.06) 830.7) 11.28 11.04 | 49.10] 3.58 | 50.20 | 3.67 | 0.64 | 2.0 The Specific Gravity of the Masonry = 2} TABLE XXI. (See page 41.) PRACTICAL PROFILE NO. 2, Depth |Horizon- ee ee , aa Pe Maxima Pressures. Coefi: Factor of tal Moment Total Front Back ? ; of Fe | _ of Water | Thrust | of Water, ee a Face to | Face to Reservoir Reservoir tio: SF Safety Below |of Water,| in Cubic S a, In / Line of | Line of ull, Empty. eens against Top of |inCubic} Feet of | Left, | Right, | Total, Ee Pressure, | Pressure, f ¥ | Over- Dam, | Feet of | Masonry. jin Feet. in Feet. jin Feet. cet. | Reservoir] Reservoir|In Feet|In Tons|In Feet|In Tons Eoui- turn- in Feet. | Masonry) | Full, Empty, | of Ma- | of 2000 } of Ma- | of 2000 lib: qui ing. | in Feet. | in Feet. | sonry.| Ibs. sonry. Ibs, [POEM | 0.000 ° © | 10.00 0.00 | 10.00 0.0 5.00 5.00 | 0.0 | 0.00 0.0] 0.00 | 0.00 | 0.0 9.372 19 59 | 10.00! 0,00 | 10.00 93-7 437 5.00 | 12.9 }] 0.95 9-4) 0.68 | 0.20 8.0 15.000 48 241 10. 54, 0.00 | 10.54] I51.0 3-93 5.03 | 25.2 | 1.84 16.3] 1.69 | 0.31 3.4 20.000) 86 571 | 11.95: v.00} II.95| 206.8 4.00 5.18 | 34.5 | 2.52 24.2) 1.97 | O.47 2.4 25.983 145 1253 | 15.02) 0.00 | 15.02) 286.6 5.04 5.60 | 37.9 | 2.77 33.7) 2.45 | 0.50 | 2.1 30.000 193 1929 | 17.69, 0.00 | 17.69) 352.3 6.13 6.08 | 38.3 | 2.80 38.6) 2.82 | 0.54 2.1 35 .000 262 3063 | 21.02; 0.31 | 21.33} 449.8 7.38 7.16 | 40.7 | 2.97 41.9] 3.06 | 0.58 2.1 40.000 343 4571 | 24.34) 0.63 | 24.97] 565.6 8.54 8.35 | 44.2 | 3.23 45.2] 3.30 | 0.61 2.1 45.000 434 6509 | 27.66; 0.94 | 28.60) 699.5 9.70 g.60 | 48.1 | 3.51 48.6] 3.55 | 0.62 2.0 50.000 535 8929 | 30.99, 1.25 | 32.24] 851.6 10.87 10.89 | 52.2 | 3.81 52.1) 3.81 | 0.63 2.0 55.000 648 11884 | 34.32) 1.56 | 35.88) Io2I.9 12.05 12.20 | 56.6 | 4.13 55.9| 4.08 | 0 63 2.0 60.000 771 15429 | 37.64; 1.87 | 39 51) 1210.2 13.23 13.53 | 61.0 | 4.45 59.6) 4.35 | 0.63 2.0 65.000 g05 19616 | 40.97| 1.87 | 42.84| 1416.1 14.43 14.55 | 65.5 | 4.78 64.8} 4.73 | 0.64 | 2.0 70.000] 1049 24500 | 44.29) 1.87 | 46.16] 1638.6 I5.61 15.60 | 70.0 | 5.11 70.0| 5.11 | 0.64 2.0 75.000} 1205 30134 | 47.62) 1.87 | 49.49] 1877.7 16.78 16.66 | 74.6 | 5.45 75.2} 5.48 | 0.64 2.0 80.000} 1371 36571 | 50.94, 1.87 | 52.81] 2133.4 17.94 P7693) 7x3 | 678 80.3] 5.86 | 0.64 2.0 85.000] 1547 43866 | 54.27) 1.87 | 56.14! 2405.8 Ig.10 18.80 | 84.0 | 6.13 85.3] 6.22 | 0.64 2.0 g0.000} 1735 52071 | 57-59 1.87 | 59-46| 2694.8 20.25 1g.89 | 88.8 | 6.48 g0.4| 6.59 | 0.64] 2.0 95.000] 1933 | 61241 | 60.92, 1.87 | 62.79] 3000.4 | 21.40] 20.98 | 93.5 | 6.82 95-4) 6.96 | 0.64] 2.0 100.000} 2141 71429 | 64.24, 1.87 | 66.11) 3322.7 22.55 22.07 | 98.2 | 7.16 | 100.4) 7.33 | 0.64 2.0 The Specific Gravity of the Masonry = 2}. APPENDIX, 399 TABLE XXII. (See page 41.) PRACTICAL PROFILE NO. 3. s OINT REFERRED i i Depth |Horizon- i VERTICAL ie — ae Maxima Pressures, Coeffi- | >. ctor of tal Moment Total Front Back - : Se Bae of Water Thrust of Water, Area in Face to Face to Reservoir Reservoir onnee: Safety Below jof Water,| in Cubic : Square | Line of | Line of Full. Empty. cosary | against Top of |inCubic] Feet of | Left, | Right, | Total, Roe Pressure, Pressure, ——— te ae Over- _Dam, | Feet of | Masonry. jin Feet.| in Feet. Jin Leet. * | Reservoir| Reservoir/In Feet/In Tons/In FeetjIn Tons} po4;. | turn- in Feet. | Masonry _ Full, Empty, | of Ma- | of 2000 | of Ma- | of 2000 librtatn ing. in Feet. eet. | sonry. Ibs, sonry. Ibs. 0.000 ° 0.0] 18.74] 0.00 | 18.74 0.00] 9.37 9.37 | 0.00) 0.00 | 0.00] 0.00) 0.00 | 0.0 16.585 59 325.9] 18.74] 0.00 | 18.74] 310.80 8.32 9.37 | 22.16) 1.62 | 16.59} 1.21] 0.19 8.9 20.000 86 571.4] 18.86} 0.00 | 18.86) 374.98 7.93 9.41 | 29.37] 2.14 | 20.01] 1.46] 0.23 6.2 30.000] 193 1928.5] 20.56} 0.00 | 20.56} 570.33 7.67 9.51 | 48.87) 3.57 | 33-97) «-48| 0.34 | 3.3 40.000] 343. | 4571-4] 24.52] 0.00 | 24.52) 793.65} 8.78 9.98 | 59.93) 4.38 | 50.43] 3.68) 0.43 | 2.5, 50.000 535 8928.6) 29.95] 0.00 | 29.95] 1065.69} 10.65 10.92 | 66.41| 4.84 | 64.49) 4.70) 0.50 22 60.000) 771 | 15428.6] 35.71] 0.43 | 36.14] 1395.80] 12.44 12.64 | 74.721 5.45 | 73.44] 5-35| 0.55 Det 70.000! 1049 | 24500.0| 41.S1| 0.87 | 42.68) 1789.57] 14.40 14.59 | 82.84] 6.04 | 81.72) 5.96] 0.59 | 2.0 80.000] 1370 | 36571.4} 48.29] 1.30 | 49.59] 2250.59] 16.62 16.72 | 90.28) 6.58 | 89.73! 6.54] 0.61 2.0 g0.000] 1734 | 52071.4] 55.15] 1-73 | 56.88] 2782.60) 19.16 Ig.01 | 96.81] 7.06 | 97.58] 7.12] 0.62 2.0 100.000] 2141 | 71428.6| 62.41] 2.17 | 64.58] 3389.58] 22.06 21.45 |102.38) 7.46 |105.35| 7.68) 0.63 2.0 IT0.000] 2591 | g5071.4] 70.11] 2.60 | 72.71] 4075.87] 25.37 24.02 |106.87] 7.79 {113.12| 8.25] 0.63 2.1 120.000} 3084 |123428.6| 78.28} 3.65 | 81 93) 4848.70] 29 16 27.32 110.34! 8.05 |118.31| 8.63) 0.63 2.1 130.000] 3619 |156928.6) 86.94] 4-71 | 91.65] 5716 17| 33.45 30.75 |112.90| 8.23 |123.92] 9.04] 0.63 Oise 140.000] 4197 |196000.0] 96.13} 5-76 |ror.89| 6683.36) 38.28 34.28 |114.51| 8.35 |129.96] 9.48) 0.63 | 2.3 150.000] 4818 |241071.4]105.90] 6,82 |112.72] 7755-93) 43.69 37.95 |115.21| 8.40 |136.23] 9.94] 0.62 2.4 160.000} 5482 |292571.4|116.32| 7.87 |124.19| 8939.87| 49.72 41.75 |115.02) 8.39 |r42.74] 10.48] 0.61 2.5, 170.000} 6188 |350928.6/127.44| 12.16 |139.60|10258.14| 56.51 48.88 |115.45| 8.42 |139.54; 10.18] 0.60 2.6 180.000] 6938 |416571.4/139-34| 16.45 |155.79|11734.32] 64.24 56.05 |114.93| 8.38 |138.69) 10.11; 0.59 2.8 1g0.000] 7730 |439928.6]152.14| 20.73 |172.87/13376.80| 72.98 63 27 |113.52| 8.28 |139.59) 10.18] 0.58 3.0 200.000| 8565 |571428.6|165.96| 25.02 |190.98|15195.10| 82.75 70.62 /111.40| 8.13 |141.72]| 10.33] 0.56 312) The Specific Gravity of the Masonry = 2}. APPENDIX. 400 TIAM~9jSBAM JT] JIatLAA (z) ‘IQQI ‘1aqwasaq ur payrey we eBIqey oy t “HONSUIOFUL JUSTOJNS JO HIV] Jo JUNOIe uo ‘apqe} Sty} Ul papn[ouUr jou s1e *zogr ‘of judy uo painjdni sem weq sojueng ey, } ‘WEP aU} JO YYSuUa| au} UI papnpoutr si 7 ‘wep oy} surofpe ‘6g aed uo pauoljusu ‘AuBULIer) UT suep Yystqy euros (1) x is S641 Z£-Lzer o's olt oor as 2 aid oe a fh igs ahabvincieceeeg oe eae ay asta * s[veq w0,01D gb ysre1ys ZIOL thir o'Sz olt gor i. te pee 7 Fite te sree eer eees s+ DART ssoIg Sp , ek iad o'gor emer are oon e 4s sees e eee a terete sees eeeeeee + +s gu0ysoUs tt deasaadee |W. Cacdeatoes 3 aor ore ne = be tees “5 Ss OOS trees Japugyeg ev i ogl ovolr 0°02 ogz ah ed ss a a saye1S payug a ster sqpaasooy | zh sy | Pl pees % Libr $:Sr LS1 grr uoroniyst0 uy Saha renter aie ae gourig i Be eaeieUp TERME ZO OE EET 1b ‘ 60S £°36 rer 6¢r bsitrcids $o61—1061 seteeeeeecees spinsny [octttrersrestececes § 9s nROMOy ob 56 Lfor L£° Sor O'gI o61 rete bo61-1061 prea shes -Aupunas jo °° Rel sweep eee PACU 6 peaing oct 3° £6 pcr fzr Lot o61—1061 eee nesses QouBLy em me seecee -uouspucQ, ge ¢ gltr o'Lgr g'Sz gee | tees ‘ 9061-0061 seen nee 55 i oe STOOD AGEL S Fee TSH AN Ze a oStz o LL o'lr PII Sor So061-0061 wee ree . . TIM SSF KERATIN STYOSIUGOT gt Wsresys 69£ 1 Eaimeene: ||) aac Sr og S061-0061 ee ne . trees *Sipa saids ce ir ally CES o'glt O'gr ztz Sie 2 bo61-0061 ernie : ‘ “+ uURUISIaY IAeT ve ss 60S + 3 matali Lor thr to61—0061 eee r . ae aes mearale e keyejoo ee peaing vs 9°88 o'lt ler gogi—r6gt Si Giants Phas Geeta) lay iarar ia armayerae ++ aadeypq ze WBress ggtz 0'9g0z O'%z L6z Lo61—z6g1 PY, e creeeeerers ss TOIOIY MAN 1f i ost o'£g o'or oz . z6g1 fe ete tore Fee Ay Sng 1. el paaing SreBind fetes O'OOor o‘or oft $6g1-16g1 ign ae cat ye 45 ale, Sacdaus: griare oir feuadtegee a & pus 6z Wyste14S res o SL o'gr Ser teins S6g1—-06gr ts ” ee Tay sereees ss sno Se peaing ozt 0°06 o'be Ser Rae B eS o6gr *saye1S payuy ps tresses ss gSuviseT Lz an OPED | *e sews S-ir IOL S6 o6gr jnoqy sere gguBIy |F wees susnsigee “aynoyy gz q8rens Beet oof arek ogt ee L6g1-9gg1 serge srt jee ie “+ + reuag Sz peaing og O-‘OIr o-tr o11 htidiealtis o6gI-Rggr Cg ER 8 fsecuhen giinae Rae eee + ooyeyaag. z ee eee Loot ots O'cl ofr sere, BhaegiL ae awe S83 Bp Up ue hee e+ Onset Ys ee Pere genes ‘ reer IQI teeeee ZOgt-gegr 6 fPS BES ew eee teases aur. a “ ayoUy ze paain:y ool o'glt o'0g oLlt SERGE 6gg1—-Lgg1 *sayeqS payug "th ae ues Tz Sareea are ogg o'0or o'zl gir a acit bs 16g1-9ggr arma alee 2 BTU [Pee See aaa R IS ie wrens Hrmieie a esUuR oz ae oSf1 g dir 0'0z gtr SETI OggI—zggr Se: SURpaug {S988 et peewee eee As neces Sate A 61 es zes z°16 bgt Sez S11 Seer Sebaae Rees oS 8 BEET gi WSIS 60S S blr u'r rh Fggi—zggt a svyinayy uviny | fr edversaygis. f) oasis we ae rer bor thr | octeeee fggr jnoqy ee eeces oa seine it rae osunjoseT gt 53 zor 9°66 rer gz IL £gQ1-Oger ws Ne a]UaZzlor) or paainy gfe o'Lbr Por IPL Pas Oggi Be ot aelty tr jeuo3 + ekozo'yT s paainy Soz giv 0°61 fer oz fbgr ynoqy Sene SAE S TIME ye eS Svan tem Sie WS Doses Sish8 a RIOZ, b ee off o' LE ut Oiee, «|! “Sedeee 16L1-SgLr reves sae, “7+ + ++ oQuraguy op fea | © jeuo3sjog $z6 etts £-se tor tS TOLT=Soet phen ee tgeeee won sis “| soquang a peainy o6r gor 9°S9 Ser Let bOS1-6LS1 vrrtessureds “ss aqueoyy | or ‘aseg doy “ysaa9 sige *1ayeM ‘ued uo ytuey ; Tae jo yydaq | “UOHENAYsuog jo eyed *uol}E007 “wed ‘ON, “HLOIM : *HOIH LU OOF WAAO SAMN-LONULS AINO ONIGNTONI (1904. UL suotsuaUI) TITXX WTAVL ‘SAV AUNOSVYN HDIH APPENDIX. 401 TABLE XXIV. HIGH EARTH DAMS.* EMBANKMENT. SLOPEs. Available Name of Dam or Reservoir. Location. Depths, Maximum Top Feet. Height, Width, Water. Rear. Feet. Feet. San Leandro............4.. California...........-. 125 28 Padawan: | Seesaw | “aesivet Tabeaud........... eee a A ore” Sedan ttc fA fics 123 20 3 ont 2k ont 70 Druid) Hall o.s o.ceesaeew sare ..-| Maryland,............ 119 60 4 oni 2 ont 82 Dodd Er 5. cin wsiniecrea ancien Treland s, esscaesuaaaaees 115 22 34 on I Sone || saipawss Titicus Dam... ee. ee ee eee New York vo. seeseeaen IIo 30 2 ont atoni | sass Mudduk Tank.............. Indl awe oes aad decead TOS |) ca seeas 3 oni 2$onr eens Cummum Tank... ......... OF © Siducsnsengisaas aaae TOR |) aaswas 3 ont I ont go DALE DIRE iiieisssesrce nity weiesae ie gens England. ............. 102 12 24 oni 24 oni Mag Marengo ........eeeeeeeeeee Algeria: sc sciaieaisases TOD |) asegue: | eeveitaaa | siadlanee ||) cama TOrsidé.. i vow esa siveews scans Beng and w scis ssa gion TOO | wesaee |) gusawons 2 waseaats 84 VA ETOW sce sis caeaeccee ee fe Rieab awakes es 100 24 3 ont 2 oni sridtslaters Honey Lake.......... ieanent CAFTA. «cows ssiewa 96 20 3 oni A OMT |. sascaas PilarcitOs és s00cise eas sa eras Be ig ariamiantiae Wanetas 95 25 2¢on1 EON T | aswlerire San Andres .... .ceecssaeeeel a errr ere 95 a0 3h on I J Ont || cases Temescal....... sianase-e. eae “ ea ROGER DIETS 95 12 3 oni 2 ONT | waters Waghad........ Wid lars oe cccamhon tierce 95 6 3 ont 2 ont 81 Bradfield........ oeoenat ell COBBAN 6 a Gisanmcunnedan 95 12 2$onr ahomt | ssaws é Oued Meurad....... ease aie PIBOM Ae yg oesiseomare eed OS ih ices! |! wleardtecee ||) teikasewre! |'|) ceeaidans St. Andrews... .sescseeeeee Treland .sivssunangaesas 93 OF | h awedhends |) Ghaxewae |||) as vow Hdgelaw coiccnsavkaie eae wan Scotland «scascasveeas4 OF f aeaskhe 3 onI aOR Tt || ada Woodhead .. ......s cece eens Breland 2 maiisicmaaors OO Ol saemadar My antaawess Ih aaaoat 92 Tot Off ss. ese sce siecsiiaree sie mia Scotland: vic sacweewceis 85 Io 3 oni @hont | scsses Nagar sat sins qucdee setanes Indla.ssi6 45 saad eee as Sd: Agnes? | ameaeeate! I (attsageua. Ii “agate Nahars a2.2d4 which proves our calculation to be correct. We calculate next the length of the joint at a depth of 4o feet by equation (2), page 22. Substituting the values for the known quantities, we get ae ea 6 oR ( oe 0 18.74) = 7o.gl555 X 9-37 + 4267) + 351-193 whence # = 22.80. We now check our calculation by moments, assuming a vertical axis of moments 50 feet (any convenient distance) up-stream from the back face of the dam. Weights. Lever-arms. Moments. 555 x 59-37 = 32959 195 x 59-37 = 11577 21 x 70.09 = 1472 77§ X 59,66 = 45999 The lever-arm 59.66 is obtained by dividing the sum of the moments by the sum of the weights. From formula (G\, page 20. we find 7 = 5.54. Knowing m and v we find u = 7.60 = ? 404 APPENDIX. which proves the correctness of our calculations. It is convenient to makea sketch (I'ig. 119), showing how the joint calculated is divided by Pand P’. 7.60 eae 9.66 agg See ee — o—— O<4x/5 OF MOpq’ 22,80 a ad Fic. 119. We now calculate the length of the joint at a depth of 50 feet by equation (2), page 22. Substituting the values of the known quantities, we obtain ae x 771 6 x (477 is 22.8).x = 76(771 X 9.66 + 8333) + 519.84; whence 4 = 27.82. In checking this calculation by moments, we carry forward the total weight and total moment of the previous calculation and add the weight and moment of the course just determined, which is divided into a rectangle and triangle for convenience. Weights. Lever-arms. Moments, 771 teees 45999 228 61.40 13999 25 74.47 1862 1024 60.41 61860 From formula (G), page 20, we obtain v= 8.14. The joint will be divided by P and P’ as follows: , j , SO FELT XK o—2-27 8. if 6 10.4 -o< AXIS oe 2782 MOMENTS, Fic. 120. The calculations for the first three courses of the dam suffice to show the writer's method ot determining the length of a joint and of verifying it by moments. The use of the different equations which must be applied suecessively in determining the lengths of the joints are explained in Part I, Chapter III. ~ BIBLIOGRAPHY. MASONRY DAMS. SAZILLY. Note sur un type de profil d’égale ré- sistance, proposé pour les murs de réservoirs d’eau. Annales des Ponts et Chaussées, 1853, 2° semestre, pp. 191-222. Sul Serbatoto dt Lozoya. Rivista de Obras publicas. Madrid, 1854. AYMARD. Irrigations du Midide I'Espagne. Etudes sur les grands travaux hydrauliques et le régime administratif des arrosages de cette contrée. Paris, 1864. GR#FF. Rapport sur la forme et le mode de con- struction du barrage du gouffre d’Enfer, sur le Furens et des grands barrages en général. An- nales des Ponts et Chaussées, 1866, Septembre et Octobre, DELOcCRE. Mémoire sur la forme du profil a adopter pour les grands barrages en magonnérie des réservoirs. Annales des Ponts et Chaussées, 1866, 2° semestre, p. 212. MarcHAL. Barrage de l’Habra sur !’Habra. nales du Génie Civil, 1868, pp. 33-46. Laront. Sur la repartition des pressions dans les An- murs de souténement et des réservoir. Annales des Ponts et Chaussées, 1868. Le Buancec. Stabilité des constructions. Annales des Ponts et Chaussées, No. 242, 1869. KRANTz. Etude sur les murs de réservoirs. Paris, 1870. Translated by Mahan. New York, 1883. RANKINE. Report on the Design and Construction of Masonry Dams. Miscellaneous Scientific Papers. London, 1881. Also in The Engineer, Jan. 5, 1872. TOURNADRE. Description d’un barrage exécuté sur la riviére du Verdon et de la prise d’eau du canal du Verdon en Provence. Annales des Ponts et Chaussées, 1872, 1° semestre, pp. 428-455. TULLOCH. Water-supply of Bombay. Professional Papers on Indian Engineering (Paper 68), 1873. De LaGRENE. Cours de navigation intérieur, tome Il, part 11, chapitre 111. Paris, 1873. Spon’s Dictionary of Engineering. ‘Damming,” vols. 3, 4; “ Retaining Walls,” vol. 8. 1874. Croes, J. J. R. Memoir on the Construction of a Masonry Dam. Proc. Am. Soc. C. E., 1874. MONTGOLFIER. Travaux exécutés pour la conduite d’eau de la ville de Saint-Etienne. Annales des Ponts et Chaussées, Fevrier, 1875. PocHET. Mémoire sur la mise en valeur de la plaine de 1l’Habra, Province d’Oran, Algérie. Annales des Ponts et Chaussées, 1875, Avril, pp. 261-389. BouviER, Calculs de résistance des grands barrages en magonnérie. Annales des Ponts et Chaus- sées, 1875, Aofit, pp. 173-205. INTZE. Ueber die erf6rderliche Starke der gebrauch- lichsten Formen von Quaimauern, Stiitzmauern und Thalsperren, mit Riicksicht auf die Wider- standfaihigkeit der Materialen und etwaige Fehler bei der Ausfiihrung. Deutsche Bauzeitung, 1875. GILEPPE DAM. Proc. Inst. C. E., vol. 48, p. 312; vol. 56, p. 337, 1876. Engineering News, Dec. 25, 1886. McMastTers. High Masonry Dams. New York, 1876, HARLACHER. Das Reservoir im ‘“ bésen Loch” bei Komatau. Technische Blatter; Vierteljahr- schrift des deutschen polytechnischen Vereins. 7ter Jahrgang. HumBer, W. A Comprehensive Treatise on the Water-supply of Cities and Large Towns, p. 103. London, 1876. PELLETREAU. Mémoire sur les murs qui supportent une poussée d’eau. Annales des Ponts et Chaus- sées, 1876, Octobre; 1877, Aotit et Novembre. Bopson, DETIENNE et LECLERQ. Mémoire sur le Barrage de la Gileppe. 1877. Dosson. Geelong Water-supply, Victoria, Austra- , lia. Proc. Inst. C. E., vol. 56, p. 94, 1878. DEBAUVE. Manuel de I’Ingénieur des Ponts et Chaussées. Paris, 1878. VILLARS RESERVOIR. Rivista de Obras publicas, toma xxiii. KuHN. Die Thalsperre der Gileppe bei Verviers. Zeitschrift fiir Baukunde, 1879, p. 185; und im Civilingenieur, 1879, Heft 1. LE barrage du Hamiz en Algér'e. Annales Indus- trielles, 1879 p. 769, et Nouvelles Annales de la Construction, 1879, p. 141. CHAPINEAU. Etudes sur le désenvasement des bar- rages. 1880, LE barrage du Chagres 4 Panama. trielles, 1880, p. 674. PLANAT. Murs de réservoirs. structeurs, 1880 (iv. p. 553). Annales Indus- Semaine des Con- 405 406 DE LESSEPS. de l’académie des sciences. —— Le barrage de la Gileppe. Migc. Le barrage de la Gileppe. Bulletin de la Société industrielle de Mulhouse. 1880, p. 44. BursTING of Habra Dam. Proc. Inst. C. E., vol. 70, p. 447, 1881. CAMERE. Mémoire sur divers barrages en course d’exécution en France. Congrés international du Génie Civil, 1881. DucouRNAU. Rupture du barrage de Perregaux (Habra) Génie Civil, 1881-82, p. 439. VILLAR Dam. Proc. Inst. of C. E., vol. 71, p. 379, 1882. CRUGNOLA. Sui Muri di Sostegno e-sulle Traverse dei Serbatoi d’Acqua. Torino, 1883.—La rottura della traversa dell’'Habra nella Provincia d’Oran (Algeria). Ingegneria civile e le arti industriali. Torino, 1882. — La traversa della Gileppe in vicinanza di Verviers. Ingegneria civile e le arti industriali. Torino, 1882. FANNING, J. I. A Treatise on Le barrage du Furens. Compte rendu 1880 (xc. p. 1148). 18So (xci. p. 151). Hydraulic and Water-supply Engineering, chap. x. New York, 1882. CERADINI. Calcolo dei muri di sostegno d’acqua. Politecnico, 1883 (xxxi. p. 217). TORRICELLI. Dei grandi_ bacini per irrigazione. Roma, 1885. — Sul calcolo delle alte diyhe di ritenuta. Gior- nale del Genio Civile, 1884. CASTIGLIANO. Muri di sostegno delle acque. Poli- tecnico, 1884, pp. 32-67. GOULD. Strains in High Masonry Dams, Van Nostrand’s Eclectic Engineering Magazine, 1884 (xxx. p. 265). DEACON. Report as to the Vyrnwy Masonry Dam. Liverpool, 1885. Hiitier. Etudes sur la résistance des matériaux dans les murs de souténement. Annales des Ponts et Chaussées, 1885, 1°" semestre, p. 795. CovEeNTRY. The Design and Stability of Masonry Dams. Proc. Inst. C. E., vol. 85 (Paper 2110), session 1885 to 1886. HErieR. Calcul du Profil des Murs Barrages, nales des Ponts et Chaussées, Avril, 1886. WILLIOT. Murs de Retenue des Grandes Réservoirs. Génie Civile, Tome XII., No. 13; 28 Janvier, 1888. Francis, J. B. High Walls or Dams to resist the Pressure of Water. Transactions Am, Soc.C. E., October 1888. HILL, J. W. Masonry Dam at Eden Reservoir, Cin- cinnati. Trans. Am, Soc. C. E., vol. 16 (June, 1887), p. 261. QUAKER BRIDGE Dam. See Reports made on this project to the Aqueduct Commission of the City of New York, by B.S. Church, Chief Engineer, July 28, 1887; A. Fteley, Consulting Engineer, July 25, 1887; J. P. Davis, J. J. R. Croes and W. F, Shunk, a Board of Experts, on October 1, 1888. An- BIBLIOGRAPHY, Abstracts of these reports will be found in En- gineering News for 1888. MarICcHAL, A. Description of the Gileppe Dam. Proceedings Engineers’ Club of Philadelphia, vol. 6 (1886-88), p. 243. SCHUYLER, J.D. The Sweetwater Dam, San Diego, Cal. Trans. Am. Soc. C. E., vol. 19 (November, 1888), p. 201. Wixson, H. M., gives description of dams in India in his report on “Irrigation in India,” published in the XIIth Annual Report of the U. S. Geo- logical Survey (1890-91). Vyrnwy Dam. Full description in Engineering (London), January 8, 1886. Abstract in Engineer- ing News, January 30, 1886. See also, zd, June 19, 1886, and December 29, 1888; Engineering (London), June 27, 1890; Railroad and Engineer- ing Journal, September, 1892. Fotsom Dam. Engineering News, October 17, 1891, p. 364; also, Railroad and Engineering Journal, July, 1892, p. 315. Tansa Dam. Bombay Water-works. Engineering Record, December 19, 1891, p. 40; Engineering News, June 30, 1892, p. 646. New Croton Dam. Engineering News, June 2, 1892, and October 20, 1898; also, Engineering Record, June 11, 1898, and Aug. 16, 1902. BuarTcur Dam, India. Railroad and Engineering Journal, August, 1892, p. 357; also, Engineering News, April 27, 1893. Butte City Dam. Engineering News, December 15, 22, 1892. Sopom Dam, New York. Paper by W. McCulloh, Trans. Am. Soc. C. E., vol. 28, p. 185. Abstract in Engineering Record, June 3, 1893. BEETALOO CONCRETE Dam. Engineering Record, September 23, 1893, p. 263. PELLETREAU, A. Note sur les profils sans extensions des grands barrages en magonnerie, Annales des Ponts et Chaussées, May, 1894. KREUTER, F. The Design of Masonry Dams. Minutes of Proceedings Inst. C. E., vol. 115 (1893-94), p. 63. AUSTIN Dam, Texas. Engineering News, January 26, 1893, and August 2,1894; Engineering Magazine, November, 1894. LAGRANGE Dam. Description. Engineering Record, March 3, 1894; Engineering News, March 29, 1894. CHEMNITZ Dam, Germany. Engineering Record, July 28, 1894; also, Scientific American Supple- ment, November Io, 1894. GouLp, E.S. The Dunnings Dam. Trans. Am. Soc. C. E., vol. 22, November, 1894, p. 389; also, En- gineering News, October 18, 1894; Engineering Record, October 20, 1894. FAILURE OF THE Bousry Dam. Engineering (Lon- don), May 3, 1895; The Engineer (London), May 31, 1895, January 17, 1896, and Sep- BIBLIOGRAPHY. tember 10, 1897; Le Génie Civil, May 11, 1895, July to, 17, 24, 1897; Proc. Inst. C. E. vol. 125; Engineering News, May 9, 23, 1808. PERIAR Dam, India. Engineering (London), Nov. 25, Dec. 2, 9, 1892; Engineering Record, Dec.31, 1892; Scientific American Supplement, April 8, 1899; Engineering News, Oct. 24, 1901. VaN BurEN, J. D. High Masonry Dams. Trans. Am. Soc. C. E., vol. 34 (December, 1895), P. 493. Witson, H. M. Irrigation Engineering. York, 1896% pp. 384 to 436. ReEMSCHEID Dam, Germany. Engineering News, January 30, 1896; The Engineer (London), July 31, 1896. : Deacon, G. F. The Vyrnwy Works for the Water- supply at Liverpool. Minutes of Proceedings Inst. C. E., vol. 126, Part IV, page 24 (Oct., 1896). GiLeprE Dam. Engineering Record, Oct. 17, 1896. SCHUYLER, J. D., gives descriptions of Masonry Dams in the Western States in his report on “Reservoirs for Irrigation,” published in the XVIIIth Annual Report of the U. S. Geo- logical Survey (1896-97). CourTNEy, C. F. Masonry Dams from Inception to Completion. London, 1897. PELLETREAU. Mémoire sur les profils des bar- rages en maconnerie. Annales des Ponts et Chaussées, 1. Trimestre, 1897. HoLyoxe Dam, Massachusetts. Engineering News, May 13, 1897; Engineering Record, July 22, 1899. CoNCRETE Dam AT Rock IsLAND ARSENAL. Jour- nal of the Western Society of Engineers (Chicago), June, 1897. Hemet Dam, California. Paper read by J. D. Schuyler before the Technical Society of the Pacific Coast and published in the Journal of the Association of Engineering Societies for September, 1897. Abstract in Engineering News of March 24, 1898. MucukunpiI ConcrETE Dam, India. gineer (London), October 22, 1897. Livy, Maurice. Note sur les diverses maniéres d’appliquer la régle du trapéze au calcul de la stabilité des barrages en maconnerie. Annales des Ponts et Chaussées, 4. Trimestre, 1897. SWEETWATER Daw, California. Repair and Exten- sion. Engineering Record, March 12, 1898. Livy, Maurice. Sur la légitimité de la régle dite du trapéze dans l'étude de la résistance des barrages en maconnerie. Comptes Rendus de Academie des Sciences, Paris, Mai 2, 1898. New The En- 407 BarBetT. Note sur le calcul des barrages de ré- servoirs en maconnerie. Annales des Ponts et Chaussées, 2. Trimestre, 1898. Ltvy, Maurice. Sur Péquilibre elastique d’un barrage en maconnerie & section triangulaire. Comptes Rendus de l’Academie des Sciences, Paris, 4. Juillet, 1898. Betusuta Dam (brick and concrete with but- tresses), New South Wales. Engineering News, September, 1898. SCHUYLER, J. D. The Failure of the Lynx Creek Masonry Dam, near Prescott, Arizona. En- gineering News, June 9, 18098. CLAVENAD. Mémoire sur la stabilité, les mouve- ments, la rupture des massifs en général. Annales des Ponts et Chaussées, 1. Semestre, 1887. Husert ViscHER and LuTHER WAGONER. On the Strains in Curved Masonry Dams. Trans, Technical Society of the Pacific Coast, vol. 6, December, 1889. BarseET, L. Note sur les conditions de résistance des barrages de réservoirs en magonnerie. Annales des Ponts et Chaussées, 1. Trimestre, 1899. InpIAN RivER Dam, New York. Engineering News, May 18, 1899. LAGRANGE Das, California. Trans. Am. Inst. of Mining Engineers, September, 1899. EartH BACKING FOR Masonry Dams. Engineer- ing Record, December 23, 1899. Avarco, J. M. The Bear Valley Dam as an Arch. The Technograph, University of Illinois, Champaign, IIl., No. 14, 1899-1900. TEsTs OF AN ELastic Mopet or A Dam. Trans, of the Association of Civil Engineers of Cornell University, Ithaca, New York, 1900. ZIEGLER, P. Der Thalsperrenbau, nebst einer Be- schreibung ausgefiihrter Thalsperren. Berlin, 1900. FAILURE oF AusTIN Dam, Texas. Engineering News and Engineering Record for 1900; also Scientific American, April 28, 1900. GowEN, CHARLES S. The Foundations of the New Croton Dam. Trans. Am. Soc. C. E., June, 1go0. The Changes at the New Croton Dam. Trans. Am. Soc. C. E., June, 1906. ScHUYLER, J. D. Reservoirs for Irrigation, Water- power and Domestic Water-supply. New York, IQOL, pp. 117 to 274. WacuusEett Dam, Massachusetts. Engineering Record, September 8, 1900, April 5, 1902, March 5, 1904, and October 6, 1906; Engineering News, September 13, 1900; Scientific Ameri- 408 can Supplement, December 15, 1900; Rail- road Gazette (New York), vol. XXXIX, No. s. RurFFieux, R. Etude sur la résistance des bar- rages en macgonnerie. Annales des Ponts et Chaussées, 1. Trimestre, 1901. GILLETTE, H. P. Coefficient of Friction in Dam Design and the Failure of the Austin Dam. Engineering News, May 30, got. Masonry Das, built by Spring Brook Water Sup- ply Company, Pennsylvania. Trans. of Asso- ciation of Civil Engineers of Cornell University, 1901; Engineering Record, June 15, 1901. Grecory, Joun H. Formulas for Stability of Small Dams. Engineering Record, September 21, Igor. AssuAaN Dam, Sluice Gates. October 12, rgor. New Croron Dam. Report of Experts recommend- ing Changes of Plans, and Discussions thereon by other Engineers. Engineering News, No- vember 28, December 26, 1901, January 9 and 16, Igo2. Assuan Dam, Egypt. The Nile Reservoir Dam at Assuan, by W. Willcocks, C.M.G., M. Inst. C. E., London, 1901; The Engineer (London), Dec. 12, 19, and 26, 1902; Engineering (Lon- don), Dec. 12, 1902; and Paper by Maurice Fitzmaurice, C.M.G., B.A.I., in Proc. Inst. C. E. for January, 1903. Ramiscu, G. Beitrag zur Dimensionierung der Thalsperrmauern. Zeitschrift des Osterreich- ischen Ingenieur und Architekten Vereines, April 4, 1902. LAUCHENSEE Dam, Germany. Engineering Record, August 30, 1902. Capart, G. Barrages 4 parements rectilignes. Annales des Ponts et Chaussées, 3. Trimestre, 1g02. Dittman, G. L. A proposed new type of masonry dams. Trans. Am. Soc. C. E., December, 1902. Urert Dam, Germany. Deutsche Bauzeitung (Ber- lin), March 14 and 21, 1903; Engineering News, July 16, 1903. Wicwam Dam, Connecticut. May 7, 1903. Betwa Dam, India. 1903. SPIER FALts Dam, New York. Engineering News, June 18, 1903. Irgaca Dam, New York. Engineering Record, July 18, 1903; Trans. Amer. Soc. C. E., December, 1904. Boonton Dam, New Jersey. Engineering Record, August 8, 1903. Scientific American, Engineering News, Engineering News, June 4, BIBLIOGRAPHY. WisNnER, G. Y¥. The Correct Design and Sta- bility of High Masonry Dams. Engineering News, October 1, 1903. See, also, Report made to F. H. Newell, Chief Engineer, in Engineering News, August 10, 1905. Lake CHEESMAN Dam, Colorado. Engineering Record, October 24, 1903; Trans. Am. Soc. C. E., December, 1904; and Proc. Ameri- can Water Works Association for 1906, p. 453: CONCRETE-STEEL Dams: at Theresa, N. Y., En- gineering News, Nov. 5, 1903; at Schuyler- ville, N. Y., Engineering News, April 27, 1905; at Danville, Ky., Engineering Record, Feb. 15, 1902; at Fenelon Falls, Ont., Engineering News, Feb. 9, 1905; at Huntington, Penn., Engineering Record, Dec. 22, 1906. AVIGNONET Dam. Schweizerische Bauzeitung, December 19, 26, 1903. BarossA Dam, Australia. 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Given in full in Engineering News, January 2 and 9g, 1892, and in Engineering Record, May 14 and 28, 1&g2. SANTA FE Daw, of earth. 85 ft. high, rooo ft. long. Fngineering News, April 13, 1893. Lr Conte, L. J. High earthen dams for storage reservoirs. Paper read before the American 409 CONCRETE-BLOCK Dam ON PEDLAR RIVER, Virginia. Engineering Record, May 12, 1906. Cross River Dam, New York Water Works. gineering Record, June 16, 1906. New Croton Dam. Scientific American, October 17, 1896, and January 20, 1900;. Engineering News, October 4, 1906. BiLacksBrook Dam, England. Engineering Record, November 24, 1906. Mercepes Dam, Durango, Mexico. News, November 1, 1906. Wecmann, E. The Design of the New Croton Dam. Trans. Am. Soc. C. E., June, 1907. En- Engineering DAMS. Water-works Association. Engineering Record, Sept. 16, 1893, p. 257. Turner, J. H. T., and BricHtmore, A. W. The Principles of Water-works Engineering. Lon- don, 1893. pp. 183-208. EartH Dam oF THE Honey LAKE VALLEY, Cali- fornia. Engineering News, March 15, 1894. Burton, W. K. The Water-supply of Towns. London, 1894. pp. 53-70. Witson, H. M. Irrigation Engineering. New York, 1896; pp. 347 to 373. RESERVOIR Dams WITH IRON SHEETING. Ad- vantages they may possess. (London), May 8, 1896. STRANGE, Wm. L. Reservoirs with High Earthen Dams in Western India. Minutes of Proc. Inst. C. E., vol. 132, p. 130 (1897-98). Fox, Wiri1am. Reservoir Embankments, with Suggestions for Avoiding and Remedying Failures. Trans. Society of Engineers, Lon- don, March 7, 1898. For abstract of this Paper see Engineering Record, September 3, 1898. Lippincott, J. B. The Failure of the Snake Ravine Dam (made by the hydraulic process), California. Engineering News, October 20, 1898, p. 242. EarTHEN Dam FOR WATER-worKS of Cambridge, Massachusetts. Engineering News, November 24, 1898, p. 324. CrysTaL Sprincs Dam, California. Scientific SCHUYLER, J. D. Reservoirs for Irrigation, Water- power, and Domestic Water-supply. New York, 1901; pp. 76 to 117 and 274 to 299. American, December 17, 1898. Druip Lake Daw, Baltimore. Engineering News, February 20, 1902. WacHuseTT Norta Dike, Massachusetts. gineering News, May 8, rgo2. The Engineer En- 410 Hitt, W. R. Classified Review of Dam and Reservoir Failures in the United States. Paper of American Water-works Association, 1902; also, Engineering News, June 19, 1902; En- gineering Record, September 27, 1902. TaBEeAup Dam, California. Engineering News, July 0, 1902. , SAN LEANDRO Daw, California. September 11, 1902. BaILLarGE, C. Dam Construction and Failures during the Last Thirty Years. Trans. Cana- dian Society of Civil Engineers, 1903. Engineering News, BIBLIOGRAPHY. WacuHuseTT SOUTH DIKE, Massachusetts. En- gineering Record, August 20, 1904. EartH AND Cris DAM ON THE ANIMAS RIVER, Colorado. Engineering News, January 4, 1906. Tue BELLE FourcHE Dam, South Dakota. En- gineering News, February 22, 1906; Engineer- ing Record, March 3, 1906. TrenaNco Dam No. 1, Mexico. Construction by Sluicing. Engineering Record, June 9g, 1906. THe TERRACE HypRAULIC-FILL Dam, Colorado, Engineering Record, December 22, 1906. ROCK-FILL DAMS. Watnut Grove Dam, Arizona. Engineering News, , October 20, 1888. Otay Rocx-Fitt Dam. Engineering Record, Sept. 28, 1895. Wixrson, H. M. Irrigation Engineering. York, 1906. pp. 373 to 379. Howe tt, L. B. The Pecos Valley Irrigation Sys- tem. Describes rock-fill dams. Engineering News, September 17, 1896, p. 181. SCHUYLER, J. D., gives descriptions of rock-fill dams in the Western States in his report on “ Reser- voirs for Irrigation,” published in the XVIIIth Annual Report of the U. S. Geological Survey (1896-97). Russet, W.S. A Rock-fill Dam with Steel Heart- wall, at Otay, Cal. Engineering News, March 10, 1898, p. 157. Lower Otay Rocx-Fitt Dam, California. gineering News, March 10, 1808. CANYON FERRY Dam, Montana. Journal of the Association of Engineering Societies, May, New En- 1898. Reconstruction of the dam, Engineering News, April 26, 1900. CasTLEWooD Rock-Fitt Dam, Colorado. En- gineering News, December 24, 1898, and May 19, 1900; Engineering and Mining Journal, February 9, 1899; Engineering Record, July 12, 1902. East Canyon CREEK ROCK-FILL Dam, Utah. En- gineering Record, September 2, 1899; Engin- eering News, January 2, 1902. Rock-FILL DAMS wiITH METALLIC REINFORCE- MENT. Génie Civil, October 21, 1899. SCHUYLER, J. D. Reservoirs for Irrigation , Water- power, and Domestic Water-supply. New York, 1901. pp. 1 to 76. FAILuRE oF Lake Avaton Rock-Fmt Dam, New Mexico. Engineering News, July 6, 1905. ALFRED Dam, Maine. Dry rubble, faced on water side with concrete. Engineering Record, March 3, 1906. TIMBER DAMS. James LerreL & Co. The Construction of Mill- dams. 1874. Graff, F. Notes upon the early history of the em- ployment of water-power for supplying Phila- delphia with water, and the building and re- building of the dam at Fairmount. Proceed- ings Engineers’ Club of Philadelphia, August, 1886, vol. 5, p. 372. Hotyoke Dam. Paper by Clemens Herschel, Trans. Am. Soc. C. E. for 1886; see, also, Engineering News, May 13, 1897. CHITTENDEN, 5S. H. Dam across the Potomac River (partly of masonry, partly of crib-work), Trans. Am. Soc. C. E., vol. 18 (February, 1888). SmiTtH, E. F. Dam Building in Navigable and Other Streams. Proceedings of the Engineers’ Club of Philadelphia, vol. 7 (August, 1888), p- 7. Crores, J. J. R. Lumber Dam in Pennsylvania. Engineering News, September 5, 1891, p. 205. PaRKER, M.S. Black Eagle Falls Dam (crib-dam, 14 feet high). Trans. Am. Soc. C. E., vol. 27 (July, 1892), p. 56. SEWALL Faris Dam across the Merrimac River, near Concord, N. H. Engineering News, April 19, 1894. Pearsons, G. N. Dam at Bangor, Maine. Clos- ing of the timber dam. Engineering News, July 26, 1894. BIBLIOGRAPHY. Harvesty, W. P. The Bear River Irrigation Sys- tem, Utah. Describes a crib-dam 370 feet long and 174 feet high. Engineering News, Feb- ruary 6, 1896, p. 83. Bisoop, W. J. The Lachine Rapids Power Plant, Montreal, P. Q. Describes masonry and crib dams. Engineering News, February 18, 1897, p. 98. Timser Dam for the Power Plant of Butte, Mon- tana. Engineering Record, March 5, 1898, p. 301. For partial failure of this dam see 7d., August 6, 1898, p. 203. STEEL SteEL Dam at Ash Fork, Arizona. Engineering News, May 12, 1898; Engineering Record, April 9, 1898; Journal of the Western Society of Engineers, October, 1905. 4ll TimpeR Dam Across SoutH YuBA RIveEr, Cali- fornia. Mining and Scientific Press, San Fran- cisco, February 8, 1896. Crip-pAM across Rock River, Illinois. Journal of the Association of Engineering Societies, July, 1896. CriB-DaM, Butte, Montana. Engineering Record, August 6, 1898, February 3, 1900; Journal © Association of Engineering Societies, April, 1899. CHESUNCOOK TimBER Dam, Maine. Engineering Record, July 16, 1904. DAMS. REDRIDGE STEEL Dam, Michigan. Enginev..ng News, August 15, 1901; Journal of the Western Society of Engineers, October, 1905. MOVABLE DAMS. Memoirs and Notes in the Annales des Ponts et Chaussées. 1839. CHANOINE. Mémoire sur le barrage d’Epineau. 1st Series, vol. 16, p. 238. 1841, THENARD e¢ a/, Barrages fixes 4 hausses mobiles exécutées sur la riviére de L’Isle. 2d Series, vol. 2, Pp. 45. 1843. CHANOINE ET POIREE. Echappements des barrages a fermettes mobiles. 2d Series, vol. 5, p. 241. 1845. LAVAL. Notice sur les travaux de perfectionnement de la navigation de la Sa6ne, entre ]’emb»uchure du canal du Rhone au Rhin et Lyon. 2d Series, vol. 9, p. ro. 1851. CHANOINE, Barrage Auto-Mobile. Mémoire sur la fusion des systémes de MM. Poirée et Thénard. 3d Series, vol. 2, p. 133. 1853. CHRONIQUE. Barrage de Laneuville-le-Pont (Bear-trap dam on the Marne). 3d Series, vol. 6, p. 252, 1855. CHRONIQUE. Barrages mobiles de M. Chanoine. 3d Series, vol. 10, p. 97. 1859. CHANOINE. Mémoire sur les hausses mobiles et automobiles: construction du barrage de Conflans- sur-Seine et expériences faites 4 Conflans et 4 Combeton. 3d Series, vol. 18, p. 197. 1861, CHANOINE ET DE LAGRENE. Mémoire sur les barrages a hausses mobiles. 4th Series, vol. 2, p. 209. 1866. DE LAGRENE, Etude Comparative sur divers systémes de barrages mobiles. 4th Series, vol. 11, p.172, 1867. CAMBUZAT. Note sur les barrages mobiles du systéme Poirée et du systéme Chanoine qui fonctionnent simultanément, pour les éclusées de I’'Yonne. 4th Series, vol. 13, p. 135. 1868, SAINT-YVES. Etude Comparative des divers systémes de barrage mobiles. 4th Series, vol. 15, p. 282. 1868. De LAGRENE. Observations relatives aux barrages mobiles, 4th Series, vol. 16, p. 50. 1868. CHANOINE ET DE LAGRENE. Mémoire sur Ja construction des douze barrages éclusées exécutés sur la haute Seine, entre Paris et Montereau. 4th Series, vol. 16, p. 479. 1868. MaLEzIEusE. Notice sur le barrage construit en 1867, sur la Marne a Joinville (Seine). 4th Series, vol. 16, p. 482. 1870, SAINT-YVES. De l’emploi des barrages mobiles du systéme Poirée pour des retenues d’eau supérieur, a 2 metres au-dessus de l’étiage. 4th Series, vol. 20, p. 425. 1873. CAMBUZAT. Substitution d’une navigation continue a l'aide des barrages mobiles 4 la navigation inter- mittente produite par les éclusées de l'Yonne sur la Seine et sur l’Yonne, entre Paris et Auxerre, 5th Series, vol. 5, p. 177. 1873. BOUL. Nouvelle Passe Navigable établie en 1870 dans le barrage de Port 41’Anglais. Hausses mobiles supportant une retenue de 4 metres, 5th Series, vol. 6, p. 98. 1873. REMISE. Barrage Mobile Automoteur, Systéme a presses hydrauliques de M. Girard. 5th Series, vol. 6, p. 360. 1874. DE LarossE. Travaux d’embellissement de Vichy. Barrage mobile établi 4 Vichy sur 1’Allier, 5th Series, vol. 7, p. 659. 412 1876, 1881. 1881, 1883. Igo. Igoo. Igoo. 1901. Igor. IgOl. 1go2. 1902. 1903. 1903. 1904. 1904. 1904. 1904. 1905. 1905. 1905. 1906. BIBLIOGRAPHY, BouLf. Mémoire sur un nouveau systéme de barrage mobile fermé par des vannes et des fermettes. 5th Series, vol. 11, p. 320. LEvy. Note sur la manceuvre des barrages Chanoines. 6th Series, vol. 1, p. 419. LAVOLLEE. Note sur un systéme employé pour la manceuvre des aiguilles au déversoir de Port a l’Anglais. 6th Series, vol. 2, p. 221. LAVOLLEE, Note sur les ouvrages mobiles des barrages de la Haute Seine. 6th Series, vol. 5, p.622. REPORTS OF THE CHIEF OF ENGINEERS U.S. A. . Part I], p. 14, Report by Lieut. F. A. Mahan on the dam at Port a l’Anglais (France). . P. 1339, Note on Curtain-dam of M. Caméré for Poses dam (France); p. 1338, La Mulatiére Dam. . Part II, p. 1753. La Mulatiére Dam on the Sadne at Lyons. Description of the new system of wickets adopted for this dam, by M. Pasqueau. . Part ITI, p. 1731. Report on a proposed dam at Beattyville on the Kentucky River with bear-trap gates. Part III, p. 1869. Report of a Board of Engineers on the extension of the system of Movable Dams to the Ohio River. . P. 2102. Report of Officers of the Corps of Engineers on the Dam on the Big Sandy River, near Louisa, Kentucky. . P. 2534. Description of Lock and Movable Dam in the Big Sandy River, near Louisa, Kentucky, by Major Gregory. . Part III, p. 2118. Improvement of the Great Kanawha River, West Virginia. . Part ITI, p. 2143 and 2160. Improvement of Big Sandy River, West Virginia and Kentucky. . Part VI, p. 3546. Construction and Operation of Model of Movable Dam for Osage River (Chittenden). . Part III, p. 2185. Report on Lake Winnibigoshish Dam, etc. . Part III, p. 2505. Operating and Care of Lock and Dam in Big Sandy River, West Virginia and Kentucky. . Part IV, p. 2358. Data on Cost of Movable Dams. . Part V, p. 3146. Movable Dams in Ohio River. . Part V, p. 3257. Construction of Locks and Dams at Herr Island and at Springdale, Allegheny River. . Part Vp. 3325. Operating and Care of Locks and Dams on Kanawha River, West Virginia. Part V, p. 3353. Operating and Care of Lock and Dam in Big Sandy River, West Virginia and Kentucky. Part V, p. 3482. Operating and Care of Louisville and Portland Canal, Louisville, Kentucky. Part VI, p. 4327. Item 8. A-frame Dam for Cascade Canal, Columbia River, Oregon. Part III, p. 2314. Reconstruction of Lake Winnibigoshish Dam. Part IV, p. 2659. Movable Dams in Ohio River. Part IV, p. 2768. Proposed Movable Dams for Big Sandy River, West Wirginia and Kentucky. Part II, p. 1667. Improvement of Mississippi River between Minneapolis and St. Paul. Part III, p. 2500. The Chanoine Dam as adepted to Improvement of Congaree River, South Carolina. Part II, p. 1683. Operating and Care of Herr Island Dam (No.1), Allegheny River. Part II, p. 1693. Movable Dams in Ohio River. Part II, p. 2232. Improvement of Mississippi River between St. Paul and Minneapolis, Minnesota. Part II, p. 2239. Reconstruction of Pokegama Falls Dam. Part III, p. 2527. Imprcvement of Allegheny River, Pennsylvania Part III, p. 2707. Improvement of Ohio River. Part II, p. 1842. Operating and care of locks and dams on Ohio River. Part II, p. 1858. Operating and care of locks and dams on Allegheny River, Pennsylvania Part II, p. 1912. Improvement of Kentucky River, Kentucky. Part II, see pp. 1589, 1610, and 1650. BIBLIOGRAPHY. Dr Lacren£, H. Cours de Navigation Intérieur. Paris, 1873. Vol. 3, pp. 174-359. Wma. Watson. River Improvements in France, in- cluding a description of Poirée’s system of Mov- able Dams. Van Nostrand’s Eclectic Engineer- ing Magazine, vol. 18 (1878), p. 339. Wm. Watson. River Improvements in France, in- cluding a description of Chanoine’s system of Falling Gates. Van Nostrand’s Eclectic En- gineering Magazine, vol. 18 (1878), p. 458. VeERNoN-Harcourt, L. F. The Progress of Pub- lic Works Engineering. Van Nostrand’s En- gineering Magazine (January, 1880), vol. 22, p- Il. VeRNON-HarcourT, L. F. Fixed and Movable Weirs. Minutes of Proceedings Inst. C. E., 1880, vol. 60, p. 24. Bucktey, B. B. Movable Dams in Indian Weirs. Minutes of Proceedings Inst. C. E., 1880, vol. 60, p. 43. Wiswatt’s Tilting Shutter-weir. September 1, 1882. ANNUAL Report of the Commissioner of Dams and Reservoirs in the State of Rhode Island, U.S. A., for 1885-1890. VeERNON-Harcourt, L. F. The River Seine. Min- utes of Proceedings Inst. C. E., 1886, vol. 84, Pp. 210. Vernon-Harcourt, L. F. La canalisation des ri- vieres—barrage mobile. International Con- gress of Paris, 1889. Vernon-Harcourt, L. F. Some Canal, River, and other Works in France, Belgium, and Ger- many. Minutes of Proceedings Inst. C. E., 1889, vol. 96, p. 186. Watson, Professor W. Report to the U. S. Gov- ernment on Civil Engineering, Public Works, and Architecture at the Paris Universal Ex- position of 1889. Pocuet’s MovasitE Dam. Scientific Supplement, May 24, 1890. CANALIZATION OF THE SEINE (describes Poses Dam). Scientific American Supplement, July 12, 1890. Tue Davis IstanpD Dam on the Ohio River, Pitts- burg, Pennsylvania. Scientific American Sup- plement, August 1, 1891. Jones, Major W.A. Damand Weirs. Describes a modified bear-trap gate at Sandy Lake, Minn. Engineering Record, February 2, 1895. CHITTENDEN, Lieut. H. M. American Types of Movable Dams and their Development. En- gineering News, February 7, 1895. The Engineer, American 413 AMERICAN Hyprautic GATES, WEIRS, AND Moy- ABLE Dams. Journal of the Association of En- gineering Societies, June, 1896. articles by different writers.) STIckNEY, Amos. Lifting Dam for Navigable Pass of Dam No. 6, Ohio River. Journal of the Association of Engineering Societies, June, 1896. BEAR-TRAP GATES IN AMERICAN Dams. Journal of the Association of Engineering Societies, June, 1896. Tuomas, B. F. A Design for a Movable Dam. Journal of the Association of Engineering Societies, June, 1896. Tue FOUNDATIONS OF THE HERR ISLAND Lock AND Dam, near Pittsburg, Pennsylvania. En- gineering News, August 20, 1896, p. 127. Locks anpD DaMS ON THE GREAT KANAWHA River. Engineering News, August 13, 1896, p- 98, and December 31, 1896, p. 426. VERNON-Harcourt, L. F. Rivers and Canals. London, 1896. Vol. 1, pp. 121-148. CraiseE. Difficultés que l'on rencontre 4 maintenir a la retenue réglementaire les barrages a ai- guilles de la Meuse Ardennaise et note sur un systéme de vanne étudie par M. Baudisson. Annales des Ponts et Chaussées, 2. Trimestre, 1897. See, also, Oesterreichische Monatsschrift fiir den Oeffentlichen Baudienst, Wien, Novem- ber, 1897. Rottinc SHUTTERS IN MovaBLE Dams. Civil, May 1, 1897. Tae Marsasacy Automatic Movasle Daw. En- ginecring News, May 26, 1898, p. 343. THE MANAGEMENT OF NON-PARALLEL MOTION and Deficient Operating Head in Bear-trap Dams by Auxiliary Constructions. Engineer- ing News, May 26, 1898, p. 338. BEAR-TRAP Dam FOR REGULATING Works, Chi- cago Drainage Canal. Engineering News, March 24 and May 26, 1898. NEEDLE-DAM ON Bic Sanpy River, Kentucky. Trans. Am. Soc. C. E., June, 1898; Génie Civil, May 14, 1898; Engineering News, July 7, 1898. Tuomas, B. F. Movable Dams. C. E., June, 1808. CHITTENDEN Drum Dam on Osage River. gineering Record, September 16, 1899.. RECONSTRUCTION OF THE LAKE WINNIBIGOSHISH Dam. Engineering Record, September 13, 1902. (A series of Génie Trans. Am. Soc. En- INDEX. PAGE Adams; ‘Ji. Was: ace saceweacieendeseins eeatenaaaewin 155 A-frame dams .......... Sia Hees lene Se'sivtewiieres 63235 305 Ahern, Jeremiah ..........006 eigis.ae wilite Wiemsee Reefs 207 Aird & Co., Sir John ..... slacaseusiere Soareia breralaieraceniese 109 Algiers, dams in .........eee005 Seen eGaEIE Tess 94 Ali, Viceroy Mehemet .........ccceccccceeneees IOI, 103 Alicante Dam ..........4- Ssh evasayere Wie aieiat ase spaacaeraie 54 lle ACIP scons ccavha leno a iaare w Sreipigineitvare Miner apeaise ee a 198 Almanza, Damssiiegine asinawieiss saeuigewen semesters ses 54 Ambursen Hydraulic Construction Co. ..... 210, 219, 220 AMerGtaNn daM8.o:6.0.6-6.0:c.nsccm ssid aseiies a4ineee eee as 128 American Wood Board Company .........eeeee0s. 219 Arch, dam acting as a horizontal ......... aiiaeiacag 46 Ash Fork: Dam... ¢chaeteciam cases ce aawinsews ss 294 Ashtt Dai, c.g: oi sive nwearede aosaswereiaeaa@ece 234 Assiout Datl 466 sa0 ska csswassearawie ss Signoesss IIs Assian Dani. se sccsossscan siiaieecsassoarsecawe TOS Atcherley, L. W.: conclusions from experiments.......... eeecesee 10 models of dam ........ccecccecccceeee Mauna 9 paper on masonary dams ....... alae weaver ereieievece 8 Avignonet Dam .......eeeeeeeee eee ccceseeesceens 74 Babcock; By. Si <5 nae sevice ad eesiieeseeeasuwenes: (220 Bainbridge, F. H......ccecceecencescceccveceees 294, 297 Baker, Sir Benjamin .........cceceeceeeeeneecs 104, 109 Baldwin, Ee Fly. cciiccisiaessi ae dgiae paanidwed eee inegene 204 Ban Datt ga6o esr ows eee POCO esses: "FO Barossa Dam sic icavcssasvasers siosseas ceaacns 126 Barton, E. Hu... 2... ccc ec ce cece nec raseceneene ce 141 Baseéll, Burt asusecs veesvaiee ee eedoeen 237, 239, 240, 242 Basseville Poirée Needle-dam .......+eseeseeeeeees 302 Bear-trap dams (gates) .....sseeeceeeccceceecrees 344 Bear Valley Dam ........seeeeeeeenceee heesmabet 135 Beauve, M. de, graphical method of ..........+-45 6 Beaver, Movable Dam ........-e0+- wren os andieenans 304 Beetaloo Dam ......seesccceceeeceencreeveeceece r21 Bélanger, M. 1.1... cece cee ee ec eccecnserenenes I4 Belle Fourche Dam .....ceeeeeeerseecerececseees 245 Bellet; He. ci.cccaackivwes dsc aearniaeeemesssoen 78 Beloe, Chas. H. ....cccseceesenccceeesvecesccees 235 Belubula Dam .... 2... sce ee cece e essen er scence 53 Betwa Dam ..... ccc c eee ee cn eee eee ee enon enes 11g Beznau Dam .... 1. cee eee e etter ee ence eee eeeee 357 Bhatgur Dam ..... see ee cece eee e ete ee ee eeeneces 118 Bidaut, M....... ccc cece cece eee e teen nee eeenaetete 85 Big Sandy River Needle-dam_ ....e+eeeeeeeeeeeere 309 Blackwell, F. O. 0... ccc cece e cere cee eeesceees 265 Blanc, M. 0. ce cece cece eect eect een nen eneeeeees 5 Boardman, W. F. ..sseeeeeeeceeeee cence eeteeeees 239 415 PAGE Bogart, JOM x siasie cseai's oaiuisie s aielvis el eneaaiaslecste seve 143 Bog Brook Reservoir. ...cecsccccccssecacccecceees 145 Bonanno, G.......eeeceeees eid ai Siete Gia iSoeReie aheod SRO 386 Boonton Dam .....cceesceccccceens saeeawis Acuna 196 Bosé; '(C. Miuinesscawayaase iNda'is cedar evenaiialesoie Save lakanea lela seyaks 220 Bosmeéléa Datt «.cccciacta setae see wcrawoas ane ee 63 Bostaphy Ws Mle cviacn ath va ccacewsn ieee ts senathie isedns- oa 278 Boule! Gates winis wats giaatinegiadisiatelgamaiedew woree vias wiaters 314 Boulé Gates on the Moskowa River.........0.se00. 315 Boulé, Ma. sj scan svisoties © cee 06 3 Saeed eee mae S 314 Bouvier, Misiiccwcsdewwaaeseis Honwiswew taeeaas 5, 6, 16, 69 profile on principle of .. 1... ecceeeeeeeee 31 Bouzey Dam, description ......ccceeeseevecserers 71 falUTre: Of aarions.cissemuiend Se caciamiaeaneveass 71 Boyd's: Coriéts: Daim -s.cieacieacoa nonanieaige se deme 128 Brickell: Ps IS: Ass soja gio see esaiat sue neve aval lahereceiieve coha wtecsievaus v's 258 Bridgeport Dam... :ssissciesesieuesaccasecaansens 128 BRUMOt GR ova dda eda wks eee G4ONE CRE G ee wedes 348 Brushwood Dams.......ssccessccceccccessscceses 281 Burbank; Geo: Be saws esau oaceeeeeesiee eoeiecges 146 Butte City Daw x saisieda snisiaciadie sce marnawaien eave 144 Butterfly Dantiavis che cimigeahadinss saae tes Ser aeaen 362 By-wash for reservoirs... ... eee ccereeeccsccceeecs 227 Cagiliatt Dant iio iguagaca eis seesboul Cue sesasice 64 79 Cagliart, NMME.OF wiisanaieddanaeererGcns $a siesaese 79 Cairns; ‘Ri As «anewe are adameaa vie wens ne neneaeee 130 Calculation of Profile No. 6 1... cceseeececsceeoes 403. Caldwell, Sir JaMmess.:aseass oes sisnowmei es oceans 120 Caméré’s Curtain-dam ........ceeccsecceen evenness 316 Canilization of rivers .....csceeeensenceereseeeees 301 Canyon Ferry Dam ...... cece cece ene nencseees 293 Carlier; Me auiag sis cc etune ses’ mateo s as Sanweeles 73 Car AIDEN siasine gia a adieckihe eR araisionen dF dies elae 264 Carstanjen, Ma, i.s.sauiaeencapieeaieuc deen eawees 358 Case, Be Win soaies seeeaaiderak a baebAw aia eGuieeun 263 Carre Gate sciwia0t ceaaasieaes Spelateyatananrers Mieaeraeau 347 Castlewood rock-fill dam ............ srala\ereGuocesesecan 275, Cataract Dam oii cesciciepaaee eae ora ialtureree andichsiaicietala 127 Ceylon, ancient dams in .......ceccecsssccccccecs 233: Chabot, Anthotily, « oicsngav vied siieaweseangs as 237, 238 Chanoine Wicket-dams..........cccceeceeeeneeens 327 Charlottenburg Drum-dam.........cccceeceeescees 340: Chartrain Damas os ccainaus seacnsawe veGhea cess 72 Chatsworth Park rock-fill dam............0.eeeeee 273 Chazilly: Dams nisise sci yisiersie wateeree ie eetnarawied ns eaves ae 64. Ger Da mie sivas upeinciaita side Meine as A ire@ med erduastins 78 Chesbroughy Te Sh. cena cieueies a racec renee 2eageea 155 Chittenden Drum-dam............000 Gisela aera 341 Church; Bi S scivsaredevnecssvemeseas acidatewa ees 155, 416 INDEX., PAGE PAGE Clavenad’s method........ ina whenge deena ne eancees 7 | Dams in America........ SHAT ope nOaies Seema 128 CIEL, sundae ak aimee omannadammeakaa dtp an eeuaN 116 in Asia and Australasia........c0eccssessenees 116 Coleman, Breuchaud & Coleman..........0.0.0005 184 In Brazil oso dup nae necaargescad neesasawerdn es 265 Coleman, Ryan & Browitcacscxcds enensendasanlonx 184 1D) EV Pisin cotanes Meneame tated oametn sss IOI Colenitaig Wass (Si ios bc daa tenad Race Sid backs aaleudieded gees 184 TED OO 2 6 cake nh SAR een £1 DRE DRARERS OOS 63 COlGrde Damir: ~ dang sine nn REAR ER EAGT ROUSE r42 It MEXICO inciacenyien Sores teae ewes, Gaaewtas 264 Columbia. Timber Dam .esacvisee ynaeueecinendany at 289 An Spain... css caxccas peamesnelesauns eee acer 54 Comparison of profile types ..........eeeeee enone 42 made by the Hydraulic Process...........00- 248 of de Sazilly’s and Delocre’s type....... of Reinforced! Concrete: cc, acats's.cocaatincieone as 210 of theoretical and logarithmic type...... 32 various BUrOpeans asaneniade Iagaedcniensadalsy ae 79 Component, vertical, of water pressure included...... ag) |\..Davies, Chester Baia cateaatanaiead ene geuia Dannes ats 145 neglected in calculations ....... 520) | Davis As JP) ocasnmhen sec erase saeyaccmels 204, 207, 246 Components of inclined forcé.....caeceececadeusees 08 rh | Davis, J; Pinsssavscsed actengntiwaaeds eae 155,158, 194 Conditions assumed by Rankine............e0e eens 4 | Davis and Weber Counties Canal Co. ........+.... 278 by de Sazilly cicsagssaneease se I.) Dereon "Gc. jacdeeseosaiawh ee takeasatakererems 89 for practical profiles .......... Bo || Debrousse;. Mian anaqyegasacandgran pavecmeaang 95 for theoretical profiles; ...c0cs2. 16 | Del Gasta Dam 2.5 .ceccesccsescuaeada ccasaes ves 59 Conflans Movablé: Damm «sic id cee cna eominewaeeds g2a7 | Delestracy Me pats ccs nsed cdicirdeesindaed pasa 4 ace 77 Construetionof dams’ wash dew aicadsdeaumadnstivngoieidn 46 | Delocre: Conte-Grandchamps <.ccnccnaiscre< onde onnseaaw ae 65 ANEA OL AY POOL ee ceasyetas don tindnakind ARR ave bes 3,42 CookE Se sisciveeawuas odaserans kosmoeeeanee 209 Habra Dam designed by method of .......... 94 Gooley,. Tu: Bs 2 ose dest soveewt ane sansseasauuued 199 MAELHORNOR aiinyate sn 's rsimeGmaian epimnsalis os eeu eaten cla 2,3 Core=walls Of MaSONFy oo sc jnessenes Paves Gas eonees 225 studies for Furens Dam by.........cceeeeeeeee 65 Cornell Site, for New Croton Dam..........0+00005 162 theory of curved dams by .............45 reoan a6) Cotatay Dam 22334 cac0 canned oseweredes a7 EV POHOR 4 ses aihcey Vinh fd SoaA mundi aintemnae Ne aS 3 Counterforts in Gros-Bois Dam ...............+.. 64 | Desfontaines Drum-dam ............00.e0eeee vega 3338 in. Pont Dani eusivecaduaseniccsegeranney 72: | Dillman, (Geos Leond sa ctaccese et dasae es aeewiimenas 53 in, Gorzente Dam 5050 atcaseseagexes 80: | Djidionia, Dam. i. casiaawesieeepen ee sare smane yd 99 Courbeton Movable Dam cain acuta daccaas sawanes 327 | Drains: Goventry, We Be acsnsntedaraun ceiasenas ThA project abvadoned: Jew eR Rae Te jaeiee 262 Qualey, Jos. S. & Cor... ccc cece cece cece eee eeee 198 Quantin, J. Hiei ssied ccrnwscae sae Astin eee GRE 207 Rafter, Geo. Wo... cect eee enna renee vecene 185 Rankine, Prof. W. J. Mut oe. cee eee eee ete ee eee 3 areas of type of.. sip: Seageaeeaveer Sale eccentricity of fire sf pressure in 2 fips af biases 38 logarithmic profile of «6.6... sees eee eee e eee 5 419 PAGE Rankine, Prof. W. J. M.: method for curved dams Of .......eeseeeeeoes - 48 IMEHTOMN GE La sice. aoaxomeyaeisrexmewe’s sepia Ay 5 theoretical profile compared with type of ....... 32 Toolsee Dam built according to type of ....... 124 Beetaloo Dam built according to type of ....... 122 Reaction of the foundation...........0ceeeeeees igs. Te Redridge: Damas dcndacas sancadacdiains need aaret aes 207 Reinforced concrete dams......-..sseereeeeeeeeeee 210 Reinold, E. K., sluice-gates designed by..........+. 119 Remscheid: Danitic-ecaccmaaed caaduwnenvewes. anon go Resistance to overturning........... 0 eee eeee ees 19 Resistance! 16: Sliding. ce sameee cetaaamaaevesaanes 19 Resultant of forces acting on a dam............000% 12 Reuss) MEG sivacn yaadamnnisenea sas saxo ine hahesannaa nine ‘ 77 Richardson, Thos. F. ........eccece0e eS iehacaiare erates 194 Rickey; James Whiss caccaware seas xa Reet es An eect 358 Ridgway, Robert ........cccceccccceeenee wiavtingides 152 Robinson, Ay: Fis cascwngesaksesacxdansaseneeeaecs 207 Rochetaillée, Dam of..........005 chahieeal @iaie SEV ateNNS 65 Rock-fll damsiicoa cc acdesstes araveai ears vaiareue eee wreeaHe 266 Rogers, FB. eevee eae eee eee ee ee ee Cy 184 Rolling dams \si.5 sis sos presence eiewaaswised eciedaas 358 Roosevelt. Dats wis. as vateaaue esdanmens « seiaeys 203 Rosetta Dam iia cciscaee hace dean vache mine wearers IOI RUBID, Ves vieoneeassatmann eran sce gisestne aipalanee eer 363 Rundall, Gens Jo As sgavuawgs veelse cvadas ss eaaeee 103 RYyVes;, Major wssves.okewans e's Laon DEEteaeas 120 Saint Etienne, dam of... .....ceccscveceessccesees 65 San Andrés! Dany 0.0: caaagienan sis tgnieen' en scatins 239 San Joaquin Electric Company.............eeeee ee 255 San Léandré Dams. p..ccdeaed deen aarmnaecceaaans 237 Sati Mateo. Dam sasuee ism srotissibatar ecaeiensuradoamy 130 Sanders); Wee His oasis wsSia dae a ev aes maedemieeacuaie 204 Santa Fé Pacific Ry... .. ccc eee e eee nana rac aya ss adeers 294 Sao Tramway, Light & Power Co. ....... acaniessis 265 Sauviat Dam (see Miodeix Dam)..... sini 5 3a gibi ara uee Savage, He Niscacnaa cevvasan aan eeeuigenm ness oa 207 Sazilly, M. de: areas of type of........... ateiatieadcnns. wane. 14a method Of i. acservccnsaw coreaaaaese ss semanas I,2 LPC Of. c ac creer reresaneawer aamsenaas » reo 3 Schulze, Osear,.5 sa aa acaaw aa tsa esaaeawnaawnes.g 00% 125 Schuyler, J. D. 136, 238, 248, 254, 255, 258, 259, 260, 263 264, 266 Schiiylérvillé Damiswsae wre eviosw eed seaweed vaaction 219 Schuylkill River Timber Dams............0.eeeee. 288 Schaeinfurt Rolling Dams.... 1.2... eee eee eee 361 Scouring-galleries (see descriptions of Spanish Dams) SGOUTIRG=PIPES cis crwaeus pas GAMO eS RE aid ds yecing 228 Sears; Walter’ Hisssiawc-ct-caawed ans sagas aacominay 184, 209 Separating Well. soc ccsanwaasedacarsiasnainacoeae 227 Séttons Dat. 6 wasiet cag dnnaqiddasdavidenaden paces 64 Seymour, Jr Js: casacautantserawiiimiaseceeaeaeic 255 Shaler, Ita Aun ovens esaeasais sean Nomad SSA Gisele 157 Shirreff, Reuben. .......... Radiata neues deen 194 Shoshone Dams «. scs-ssancinaiaseesancteaayeaanwns 207 Shunk; Wink Fasuiiscessongeoe scare nonss acca 09 158, 162 Shia te r-aS so. ssaig c evand.cvauesenngcianaueayanenada syestioere ya boegtaecd 325 Shutter-gates, early ........ 0. ce cece e econ seetsee 325, 420 PAGE Sioule Dam........ GARD chil ig ha aORNSs 8b anangpeceual uayocaheraecs 75 ir ee acta cide aaiieee siiiehesiesebiesiee —29 Smith, Gy Ba sa.aecsdvecetesee cuctnaneweneessen. TE: Smith, ‘Cy Wass ses Mopaie Has vies CaN NRE SEN Kee. LOM Smith, Bs. Bocuse ayeceand eee DE eee emma eee ee 243 Smith, J. Waldo....... Peed ionmgigmarcdenl7O, 14, 707) Snake River Dams...... irae SAWwanNMeaewew ees sages “255 Sodom Dam. tho eA Nes Aaa ep eem Sees ene, EAS Southern Caltfornta Mountain Water COvieranaee wea OUe Spanish damsii sais cscmsdawiee sav gai necws sia RA 54 Specific gravity of masonry: assumed by various writers ..... eit Saves 2 of Termay Danis, iseswsodiasene Sakae Bee 70 of Vymwy Damiic.s ius ee cease nace pierieiscelatete vous 988 Specifications for New Croton Dam................ 367 Spler Balls: Watts: aavaeisas act ewer ccdarecaude sacnwalene 194 Stearns; Bi. Piss igs aera wagescee ecw vis ore erersyanamrerwreee 194, 244, 245 Steel DaMse ie taps adoacseaialasie mameleeewien weet + 204 Stokes, Fs W:. Scniwasitesiadeecenciwwats Swregeecean TOD DBLOME YS JP (Gi Mina: tind so wlaisa ore cosa weve avacandeanads + +351; 357 Stoney Roller Sluice-gates.......... secure LOZ), B50; B57 Stop-cock vault for dams........ Aviles aaaleeaebe ee 231 Strachey; Genscan pa cae saan cine iis AA eS 119 Sullivan, Rider & Dougherty......... siteraei guanine - 146 Suresies Dates cssccsceidans caweags we sneeeeaes 322 Sweety. Blnathatts scaeasiwisesie'seaieceres deniewwmmwewe, 1243 Sweetwater Dam....... SieGuee als Wisewmivesnees 130 Tabeand Dam. .........0% Mmitnimavesciaeeiae 240 Tache Dam........ jeeamesoede istadneshesesaaae 9172 Tanks in India.......... Sisbaseieels ss ‘iaaiiwwaiuaamnek.> a8 Tansa Dame: isasaacs anes s SN apseaeeee dene LIC Teichnidnny Fa caavcesrerersaionrn sqacwinenwaene Od Temescal Dam.......... sisiaselayesn weet ipeweeosmmnye 239 Tenango Dam........... a anareie WiGAR os enWES eee OF Tension in masonry.........0+ SiS Ria aN Maae 4 in Djidionia Dam peealeaemuens shaccameaniaase 100) in Hamiz Dam.......... Seales eo eRe eke 100 Ternay Dams «0 2s0s0es. anisiereuseaynecya ae avaraiecatawienese 69 Terrace Dam si ciasewrnewanwse jiesvnoneiwaanne 263 Thénard Shutter-dams ...... dine sys axes siepere aie see 325 Thirlmere Dam ......... HRS Oe Pairea a ainine die 89 Thomas’ A.-frame dam.......-seccecsecccecees 323, 365 Thomas; Bi. Pisces cacneaseneee ed anaes «5302, 323, 363 Tibi, Dam Of i.-cc0sicacece WME OMe edepeserdale,, LAGE Tillot Dat axcoscscwsiesss niwhe sea Rwes oven (OM Timber Dams ......+.-04: enaieale ea agtane deals wa 280 abutments ........- Chote neneereeeseees scone 282 APTONSs aneesirasnes ee vixens BN eee NMR E ts 281 leakages occtneatewewewe ses ai sapeneds oe .. 281 PTOMIES... 6. cs sete aeisgciew se ves (MM teneEeeeee BOO sheet-piling ........eeeeeees shomapegeasednns 2OE Titicus Dam....... ha RORTeS aiela@ slararwtareie ed. o'aaye 150 Tlélat Dam.......sceeeee se eeeenens Benda rnsehaie » 98 "Toolses! Danis. oes dsereateu ese eabee ciamees se aiaeceaie: 1 ae Top of masonry dam, superelevation above water of 36 Top-width of masonry dam, size of........ seasnrartne ch 36 ‘Torricelli, Signor iiacc nese ewea saad de Ve ees aes 104 Trapezoid representing reaction of foundation..... wae 08 Triangle representing reaction of foundation ....... 13 INDEX. PAGE Tripping-bar for wicket-dam ......eccessseereeess 330 Troja Dam........... ak shecagemealnneessapasem | B08 Tucker & Vinton, cccccanvacccivcewsauenen an one 808, 219 Tullock; Major... wissuweiciss nieces ee ieeias 106 Turloch Dam (see tupraaye Dai): avewaienceeases : Turdine Dam. inacs gigas vara vewreioe bkausmarasuaeane “FO Twin Falls Land & Water Co.....sceeeeceesceeeee 258 Tyler Dati ss wis esaas eeiauaeatis sie R ada Mie waco ens . 248 Types: comparison of de Sazilly’s and Delocre’s........ 3. comparison of various...... ere Depesaewee fd 42 Practical, 1 and 2...... Aniehmeresa naa: BO! Theoretical, I and II.......... Semester BO) Ty tant Dati vin sc-gaae ee atin eons ieee BE Upper Otary Dam...... sioaeeys Uwe eecesseya 220 Urtt. Damiss-vese goss Oe OE oer Sipe Hie aciay +. go Val de Infierno Dam......... WMmieRedeaK ose SY Vale, By Rig ¢ie0+aacee saad su ee via eseenmee ee » 184 Valve-tower........ Raves BvbeyatonaueGtiors ie biokGramomeieeeres: 220) Vassy cement used in Furens Dam. .......-.20000- 66 Veliaty Datta sao. y sce eciswiserecdns susilargters ecard sbcar evens awe: 2235 Verdon Dames iwc en sis sa ea:dusvac aces Mike veeeaeinee 270 Vertical component of water pressure: effect of including.........eeeeeeee iweeromine 2D omitted in calculations by Rankine ..........6. 5 omitted in finding Theoretical Profiles .... we 8S Vicat, M., gives crushing strength of mortar ....... 70° Villar Dam, sovus ovens ainGGte wiaisieeras arene Mew § NOT Vioréad Damivs.scssineuiewsve Gaweltcacs. aiaeand siesta . 63 Weis: Daltices nascaaees Seaieias cas dgmektweas 82 Wachusetts Dam... sseeeeeeeee Boyan geAerere mine eee 185 Wagoner, Luther. ........0005 eoeccssceescsesese I4E Waialta Dam, si.-.scae-acass esa srethacenieearsrane waaistereree: 2150» Walnut Grove, rock-fill dam........ Sinauainerene 269 Walter, R. F.. S pihieenavendiohece oe-p Sue Termeni 2A Washburn, Shaler ‘& Washburn sib SRM mM Meee erete ESS Waste-pipes ........ Suigaeiwisnlsieadniats RS eteseicts isaieees 220 Waste-weir .......... Haldieeiawen Sask GSA Lesa onghOy 225, Water pressure: effect against curved dam........ceeeeeeees sare AF effect of vertical component Of...........e00082 © 29 hydrostatic, considered only...... eres sis aie Gimiene- BO vertical component of, neglected in calculations 5, 20 Waves: PesiStANet 1dccccaddseiasasnbeeckesodate een + +20, 34 Weight of dam to resist the thrust of the water...... 12 Weight of masonry: elect Obs vcs aaiiae eases ceeeesniayeees etnies, 2S given by various authorities... ........eeeeeeeee 29 Weir-formula........eeees Pst eaeeewenees 296 Wells, Chas. E...... aicvie ag idedve 4.8 a rarevermamnewidre bw ¥ROR LOGO Welsh, Ashbel.......... AGC SARE MeeeReee: | B44: Western, Lieut. Colonel .....cccceeeccesecenceses IO4 Wheeler Edgar TD vsiseyoscattocsiesiccanemaes 40) White, Josiah ....... DiiTeededea swsemiemeeeeses: 344: Whitehouse, F. C....... ce veecesesnagcenessensens FOO Whiting) Jy Biiescs tsa weer (kUie es MaVesowENeRee TLS Wicketsdams. ccc saessaaesdbsuaian eonnamwead dacs 32? Wigwaln Dats isavesvbsacswicieas caeeeua depeeenge, 220 INDEX. PAGE Wiley, An Ts. anid biaaeuatdaewaaraabegdacmaeces 202 Willcocks, Sir William........ceecesseeseee+103, 104, 109 Williams, Prof. (G. Swuinsscaaeedaeaaas aan eaeabuve 201, 202 Wilson, H. M. ............118, 119, 121, 124, 220, 233, 234 Wilson, W. Ji casa ncees 164 RG RECT E LEER RSE 109 Wisner: (Geo: Va teadannavcnsisduaialnade das . .46, 204, 207 Woodward, Silas H.........0ceseeeere sate ede wad 46, 199 Working-needle-dams, method of.........eseeceee4 306 421 PAGE 235 i18 Yarrow Dam Yeuland River Zola Dam, acts as a horizontal arch........+eeeee+ 46 description Of scssascdcnes {eteeine eons: Ox, Zola, M., projector of Zola Dam ww eeeeeveeeevees O64 Lorn; Gs We aie-svasunscess Mes Sabeeine i Use oN eaie> -<202 Zn River Dam aoc sasreaweagy sassmecereescoaceages: 200 PLATE SAZILLY’S PROFILE TYPE SCALE OF METRES. O12 4 6 81 0 250 2.50 125|156/2.61 / | / 137]192,/3.25 /3.00 | (47/235, 3.87 | je75_ 3:32 | LL PLATE ll. 6 SCALE OF METRES Oo? DELOGRE’S PROFILE TYPE _10 aN . wo co oO So o oa 0 o o wo T aie a a a a S| Ss SaaS SSS PPO Ta SS HP SSS scores ese r | \ ' ! 1 1 \ ' \ | ee | + | ! ; ' i | ' ' ei | i | { I i ! | l | ! fnew ener nnnn pone | | \ Ni 1 f : | ol 1 1 \ ' ! i | | * bot * r T 1 SN oO} ! I 1 o ! | on | ol} 3 oS al o 2 SSS S Ses staaec stows. We seseese S) t =| “ a ee ta mt a t “Sea t ' \ L ~~“ Sete t 4 ty. TP a ! wm os, PS 4 ey VT. a 2) ae oe a a fat oe a I ! RSS, ~~ o| i Seis SS | i ee Sie | mI ol 7 Se ow! a hee, + Pet 1 PSS ' on Ete, 1 x Si 1 ° | ~~ Qe Ww, Sat co ! 1 = 1 1 | “Smee, ' SINE Soo ot ' t ' 1 | \ l 4 ' I 1 oN IS | N| ! 1 | ' | 1 t 1 { ( \ \ | i © ! ry nw N 74 ae A Se ESSE SE EN PLATE Ill. PROF. RANKINE’S PROFILE TYPE SCALE OF FEET. 0510 20 30 40 ns eins) 9.37 9.37 0 73 10: ore 00 = 10 11.62 154 1089 = a 20, 12.13 3a! 11.79 a iS ae 80 1257 4g 1285 [| / 13.01 00] 1402 | -/ (1448/1962) 1686 | 1583 / 885 {1887 / ~ ATE O88 2051 2039 / 2232 | 227 / | 23.9! / 2503 | 25.19 | a (2840 / 2758 | 2802 / ee eee Oc BE Se (aassese nos ___/ 3703 (4885 84.83 ; 38.19 / 54.82 it om _ 100.82 dl 39.09 Z 61.59 wr 119.30 : 3976 Z 69.24 COMPARISON OF RANKINE’S PROFILE WITH THE THEORETICAL PROFILE SCALE OF FEET o.6 10 20 30. 40 SSS PROFESSOR RANKINE’S PROFILE “ae ----- THEORETICAL PROFILE . p be So ON Fi ate EI a leaner 4 PLATE V. KRANTZ’S PROFILE TYPE PS ea S SSS Se Se Se SS SS Sim 11.71 Poo - Poo ee 4 1 | \ ' 1 \ \ So o! + 10 rey a nN oul N ' si eetow oe bnsirmrasiae es | 2 oS! Go! > +--+ ' wo 1 a PS a | Tet al °7; ee mt Tt x Mee a +! il Pee + : re Tose ' ‘ at cc 2 | Z i 2 1 | i 2 a 31 Bb 21 i 1 = i 1 oy va \ uy 1 cu | So | 3 - oo ° 0 oS 0 a nq & 3 OG et TIT hohe neo por asaSes (RS eSs SSH SSeS Sa Sseas= a Sa eS eE ntcterg means ae 17.01 ~ 4 | SS wl | Ni + ol 9! Seuss Het | 1 eat ( 19.09 EE A SEN ea sh heh tee t Lt t t ae es 25.31 28.16 PLATE VI. 8 6 4 2 SCALE OF METRES 0 PROF. HARLACHER’S PROFILE TYPE o. A a So Oo oO Q °o °o os “ S ° ° ° 2 S o e 0 S 3 S Z AS 1 2 nid a oe N 3S ai re) N °o “i 9 : oO “ wo nN = = =- N io N N So tse » 6--8S-e-- ree Pees oa Taree we i acai fae ae ere 1 ' : | I H | | | | | | , ' | ! 1 ! ' i | ! { ’ | | | | | { \ \ i | { i | ol ! ! : . 2 \ wo) | © , ! \ f \ \ 1 | cl | | | | | 1 | i 1 | oO oO} “~ ° ° ol \ tN \ { i ; os fF ss a a SG FF FH BS ow @ i of ot | ajo ea Se OSU ll CU SC ll a a = OL -- Og See | { ‘ a 2; o N! G o : a Oo, rSses are wo \ v i 1 : a = S fo (Ae. ! ! ! ! " a |e pee | | | | | uy oS 00} i ESS a i i \ 21 ~sst ai! 74 eas \ \ | i 3 fs wo | ee \ > [pee A ol ol ee | See a “OM ! sea | ots \ NI | I | =| co! { | : a o Bl | | ; ! 2 3B \ 0, ord o! i 9) ! | or | 00 | J \ a \ o| Ss ' : | £0 oe | \ o ' “ 1 | | 1 i Te : | Poe oO} J I I 1 cae S| i a ae . \ @; : \ ! | | Sy - ! . ¥ nl | & ! NI \ : N ! 4 ’ Z I N, | oo | 2) \ ©; f \ i oe vo | . | / ( t 2 ‘ 1 1 ' : t I ‘ | | : 5 ’ 1 ; / | [¥# PLATE VII. CRUGNOLA’S PROFILE TYPE 15 6 3 10 SCALE OF METRES 4 PLATE VIII. THEORETICAL PROFILE No. 1 937 937 Ti ScALE OF FEET i — o 5 10 20 30 40 =a Boece ; Ih =! il aaa i! i! foal) | -—4 ry [—-—-+4 Vy }—__. ry --——| F | To eri — i | +— i i fie I | f i | i) nipieds 9.37 pee eee al / ue / ! j | | fe | Ps | 579; 915 9.82 222 ee —=an - r---150 / { / | Iaer_ 1282 { 1On --4 60 | 9.43 / 15.42 12.02 ° e I A prea ~-£_ 4 --1 70 1 1 | 18.385 __ tae --- 80 i | 1 I gos os ian ee eo IE | | \ t Ee / fa a a a caps ee ty ck WOE ied --4100 I | | Be a ae 20.32 | iio { Ve 4120 ! | ' . + 130 ( } | +140 { ' | +150 | | 160 ———— PLATE IX, THEORETICAL PROFILE No. 2 a, SCALE OF METRES 0 5 10 20 30° 40 i = A 37.47 50 60 70 80 90 100 10 120 130 140 160 160 PLATE X. COMPARISON OF THEORETICAL PROFILES SCALE OF FEET 0 6 #10 20 30 40 SS PLATE XI. | THEORETICAL PROFILE No. 5 WITH INCLINED JOINTS SCALE OF FEET 0 5 10 20 30 40 wa ee PLATE XII. THEORETICAL PROFILE No. 5 MODIFIED BY M. BOUVIER’S FORMULA .; SCALE OF FEET 0°5 10 20 30 40 SS 937 937 0 (U61 (1.39 | 1183 r ! / 14.07 _' 14.07 | 14.07 / (16.63 / 166) 16.63 a SSeS ec OS Se a ea eee --------—-- --- tS ee eee Jee eee ee 30 SCALE OF _PLATE XiIll. — THEORETICAL TYPE: No. |. SCALE OF FEET. 0’ 0' 5 10'15'20' ‘ 60 /) / /| feed i, | / | | es / | / | - H | y | / | / / / / f | | / / / - / / i f | 7 | / / / / / / / | f J i / / | | / | | e / / | | / | | / / / / | } . / / | J | | J / | j | | / / | 7 / | 43.64 Zz 43.65" } 43.64 | 200' 130.93 _PLATE XIV. PRACTICAL TYPE No. 1 SCALE OF FEET. 0’ 5’ 10° 15'20' 40 60 esr é oe | fie ‘667 ae ? | 10. o/s wat / 13.61, J188| 57 mi 1496 _/ 1283 | x i Sot fp HF ee ee ee Ht 43.22 / Bt Baa By Sed ee eae seni teh PA eh Ot et Rat pe See eee eee, Ca a OL a 4 OOS | | 40 Peas 45.33 THEORETICAL TYPE No. II. PLATE XV. SCALE OF FEET 05 10'15 20’ 40! _ 60 20 QO | | I eee aes | lj See] Ea A poe eee | A = 674533. 10 30/55 Sere 10 fo | 792/559! 10.24 40 tal rene re 2g tal e a 961 /8.26| 10.96 |50 a eee ees | i / (56/03 | 209] _|60 i 303 / 12.97 jiso8 | 167 ; ee " / i | 1640 / 16.40 1640 'g0 a a era ae is87 / 1888 / iss7 | {90 Sa ge SS i ; | ee a ae i100 _ i | | 4 23.57 | 2357 HO = pg Te ee Ba / 2585 [| 28.85 1120 / 2585 | 2585 | falta | / | 2811 / 2810 {130 OO Go er ce et |140 | | | rea’ —SeSe —_ f—SPBe ee eee 4190 | 3477 | 160" | Sa Sepa | ; , | _. 3697 ) 3696 || sO T ! | ee: ee ee es NU f { 4138 | 1190 / i | | AO | 200 (3071 PLATE XVI. , PRACTICAL TYPE No. 2 SCALE OF FEET 40 O* 5" 19° 15"_20° . a —— s = 60 —. BE Nae +40! | 4 \ / | ‘07/876! 1121. (10:0778.76) 121 _ ees 4 51'967 ! 7'99/553 10°37 / ------=% : SE Sis Siena ee Faye Vy eee 1 37°61 Seat { SE io ce Ree Deca eae | : | ree seer aes 4.4.13 deseae tess | PLATE XVII : o N . 3 a ° + oe = oO ° w ° wn ° gapranese ee eatin EAM out nee N oO oo vr t+ wo r eae oe loa ee ee ees Pee see pees Ses a ! | j ' 1 i 1 ! ! ' | | | ' | ! 1 1 ' ‘ 1 1 1 | ' i \ ' ! I i 1 | Moe i \ t ' 1 ee 7 | fans A 1 | \ ! \ I ! ' t Q ' ! ‘ ' | 1 MS Seatac n, el ©} Nn, I Hee : 00) ! FS N! 5! ei STS Sa | 0 or t+ v I, \ ell °o ( ! =~ 1 1 = es { ee ! Pr a | \ ae t | Wiel nN! \ eS I \ I OEE ti It I Sy i ' : = mn ! ' i 1 i rs ; | SSG 00! = es ' s 1 o = | “ al, o tlo = I / | ! Nio fo { S| 1 Laid | fe Re ae! to - ee WD 1 7 Sh LL ie Noe “NS Cc) v fee | ' Ske! co Ss “hs ( i ist 1 1 ad 2 2 ZT On, 2) © 2 “1 — 1 Cs) — 1 n © = <= ! os x PLATE. XVIII. PRACTICAL PROFILE No. 2 SCALE OF FEET 0 10 20 30 aan ng ia tt | 43711 6.00 [~ g'a29 I i | 93.158 5.03 i 0/277|_ 5. / ' food | I : | 5:60 ; { (6.13_/ 548 | 6.08 i ! /7.36_/ 681 / 716 || i f 8.35 4 ! £970 / 9.30 i_._.9.60__ _ 10.87 0/1048 10.89 a 1205 7/38 1220, 1823 2.75 8S ! 14.55 | mannan nana 1 65 | 15.60 aye ie ON a a 170 1 oN te ae digg | 1 | tot WI DG Noose tests | 255 cy Cea ar WOO oe Nae i | 1989) sf 199 ! y : 20.98 | wfor waren ne eR gn nnn ban nnn nn SOE 8 nnn 795 | 22.07 aeeccioccgealine s _ PLATE XIX, | SCALE OF FEET 0 5 10 15 20 fo __—8”0 18.74 +0 { = SSS Hl SS = - R =50.289 8.32 11 9.37 I Reco ee OS ene ee oh aan Re ao 16.585 Pe. ia Lanne 120 Re t Boy a ! S5 7.67 9.51 i Paso |e it 1 t ' i 8.78576, 9.98 140 , ! | | 838 /10.92, a ieee tpi aoa 4 50 / ! | - f | | HEAT L108 | 12.68 ll ee See a 4 60 Fond ‘ | ee 470 i 16.25 jf 16.72 Tails 2 ee oe. x iz STABILITY OF PRACTICAL PROFILE No. 3 FOUND BY _ GRAPHIC STATICS SCALE OF FEET. 0610. 20 30 40 -50 ee SCALE oF FORCES. t INCH=—369,314 LBS. 10 No XX 3LV1d PLATE XXI. ALMANZA DAM ‘SCALE OF METRES 0, j 2 4 6 8 eS = 50 2.00 6.10 SSS SSS eases 13.50 ° o 3 Q a °o Sm oS o = 2 @ a a sap eeeees PLATE XXII. = 5.10 asso 779 ---410,20 =-4 135 Sa 10 8 SCALE OF METRES 6 f----------------- += ALICANTE DAM PLATE XXII. ELCHE DAM SCALE OF METRES PLATE XXIV. 10 8 6 SCALE OF METRES 4 o12 PUENTES DAM 1089 12.525 16.70 -4 iat Et hi 24. 25. 29.70 sere eeces 33.94 40.86 --------4 39.60 PLATE XXV. GS Bl SLi ¥S 2) SZ Iv SL el OL 8 9 + @ £ @ S3YLIW 40 31V0S WV ONGSHNI 30 VA PLATE XXVI. NIJAR DAM SCALE OF METRES. | 2 4. 6 saa anon Rae PLATE XXVII. Ov VEE 7 G XG NO ee oe LIF LEAT. Lie z Yj; E o {a i AZ Ze, Ir es 2; QA BY QL BEER eae) Uy Zi 7 a Me LD ¥. Ze Fa Yi a SaYL3aW 40 31v9S WVdG VAOZO1 eel == OZ Ol 0 eK Ae, PALE | | i ! 1 | | { | | o Ir r | | oO oy oO Ps fen ene a i i T PLATE XXVIII. o a3 Joana ===~----4 9825 4825 : 58.25 68.25 78.25 88.25 0 30 SCALE OF FEET lo 6 VILLAR DAM PLATE -X XIX, 20 HIJAR DAM SCALE of METRES 6 4 2 _ ——--—~—— ————— --—- -—-—7- 44.80 —_ PLATE XXX = LAMPY DAM SCALE -OF METRES 4 2 4.90 1.25 4.93 1.17 PLATE XXX] 4 SCALE OF METRES 2 VIOREU DAM so L PLATE XXXII. 4. 2 BOSMELEA DAM 0 <--00'I-- 8.50 PLATE XXXiIll. See 4 2 f-- 61 I= 11.90 PLATE XXXIV. 8 6 2 V 0 G OS-BO 1S $s DA M 5.00 ‘a PLATE XXXV., ZOLA DAM SCALE OFMETRES. 7 T1020 10.0 17.50 oOo 9.0 PLATE XXXVI, FUREN’S DAM _ SCALE OF METRES. o12 4 6 8 10 Se / _445 /259/ 5.0! Go ee 17 PG / pO ~ oh Go on pa sear Jeg | | | | | | | | ! | \--~----~---431 | 50 PLATE XXXVII 6 cern weE ee wo ite) xo ' ¢ 2 re Oo m So © oO “ wo N an © wo oO o fo} tr gone S9e--- a , = = a = “ vo un wa a oO ° oe Y Tier T 1 ! = — t 1 1 ' 1 I i t 1 ; ! ( t 1 rye ' i ' ! \ ! \ 1 | ' | ity 1 1 t ‘ ' \ ! | ! 1 I aa ie ! 1 i | ' I 1 f ! I \ | | ' ft i i ' 4d t f i 1 ! i ‘ 1 ' t r 1 ' ties ia | \ | ! 1 \ i roy \ | yd x t : ‘ 1 1 if 1 \ ' — a i ft #4 | ‘| °} | { | t nN NI 1 I I i | t I i It Deft ' oO: = I -o, < 1 | ' ' '& t 1 o! Clq . Or i sr x ol NI ' io! $1 oO! nu 1 i S n ow be S| | NI st Rio} ti i NI eo! De vi i + | L Se ae Sr : at ais \ \ | { ! t (0 (hp RSet t 1 | toy t | i ' o! ae Hea clea taal 2h || 4 a! t o} { TE L i yo i fs \ i]t xl i Ny °o; wn! ' aa oe ' ! | | ' i ry! 0! to a} Bw Lo apr seato iy : ~ el ce | Sm cad ‘| ™~ —_— -~—— i el 6} Sa PrnPeRe ty t! Te om! Sr met || ' \ weet DM a) ost i Tt, mrt ao; _! { ! 1 ree o! al = HSS it 1 tig! | Ni wl ! 1 | | =) ee ee a a ee ee ) I o! ! 1 a ' ie, ; a o: ! wo; i , { ss ii | t T! = o! ryt ¥| t or t qh ol | | ' wl on! col] ! 2 | t ao: ~h 4 I I { { | ioe] oO x: ' | | Pos I I i ©, id | I rie ee OO st i t ot | | st! | 1 riN i \ at 1 \ Pe { 1 i{! | im || ps Cesc ‘14 th Ie ti | ~~ ! Ip, MO t t eli! Sy ay Br { ~L fe AGT { ae w) ! ( | 1 i I ' 1 I ' 1 co it \ I 1 | : 1 { | ( SCALE OF METRES 2 4+ TERNAY DAM 0 9.56 - -- ee ee ee Ot ee PLATE XXXVIII. 4 6 8 10 BAN DAM SCALE OF METRE QO 2 FJULIW AFI SOO YILLVG é 082+; PLATE XXXIX. 8 10 SCALE OF METRES VERDON DAM 4 Cx KK eonsery EN: Th ii ‘ QO dace? gale as | er . Z Ch es ee \ LK f ey ot ie oe a_ [eae oP ee ee a | ae, 3 1 - ieee Hq Pelee eee \ | o, } |e eral em : cr al ees ! ee Ae ee ' at Cel = LL Gf eager eg, qe eg BP -3¢-4 oo it 4 | poe OF f= “0 \ : it Ml | 3 Ab Se : oegiat ro ea, 2 a a” Pete |? | a fo! | ye ere in! Ms Fy iat If ae | Ls +! es £752 \ a, 19 C | u ¢ *f ty ob ( Vi | ek ab O wae 2 | tee," ibe 4 ee eet a bec aee se Te { \ \ ahs —l-- be | : SS Sees | ee oe if Kp ie Hd | | ead ' ' | ' ‘aS aa Aes ee hoe hanes ase = SLO 68°8 "| PLATE XL. BOUZEY DAM oy 2 OGALE QFMETRES ig | ee E.3731 £.372.95 E371.95 E.367.60 R.17.506 E.360.51 SAND & GRAVEL E.355.5 1S a an cI" E,352.2 S eeoaeseae y 0 g ’ i | | (hae AO ee PLATE XLI. 15 PONT DAM SCALE OF METRES cae: ae > SEE | oi Dim [S00 3d01S 0092 ee Ses ial ha a te L 1 | ‘ , oon sae ae poo ct tere er er nnn ene ne 2 = = +--+ CHATRAIN DAM SCALE OF METRES. 012345 10 a a ee a” é 7 - 30 J 2 ” P oS 5 Oa” a “ ue z Z , Z Z a 0.34 ON C34.80) 14.53 \ (41.30) \ (47.50) PLATE_XLIl. PLATE XLII. eee 1 -3.50--> |} o 2345 67 8 910 k~-00°€-- 3 4 MOUCHE DAM. SCALE OF METRES, ---3.50--><¢ 0 f---~----—-7.60,2--------» t | | | | | | | | | | | | | | | | | 1 © o a oO N I | | | | ! ! | | | ! ! | | | | 1 L | | | ue ! J ! ° ° 0 ! \ ye i ' 1 1 - -- - — 20.2938 -— -- - ~~ ------ we -- — PLATE XLIV. Fic. 1 —Turpine Dam. Scale of Meters T T T T . 6 8 10 E250) 3 xe a wo Bg Ee a e 5 \ YS : | | C_ Bts0 ; t | | : | e ™ I s a | = 3 | e. ' gS Ne co 1 e No Zs | “Nee ~~ % G | a 1 @\S 1 ! | | 1 | | | | | | | | | ; E)-24,50 | jo. 4 | 2.254 18.25 I 1 ' ! (4 18.16 : | be 20.35 19.03 i { Fie. 2.—Mioperx Dam. _ PLATE XLV. 0 CAGLIARI DAM SCALE OF METRES. (22 Bae BG 7 PLATE XLVI. GORZENTE DAM SCALE OF METRES 12 10 k---4.00--» k=-=-— 7,0@ ------4 = = -- == - 5 - = = ¥-4 -- - --- -- K--- oro ------ ist wy) ' oo : oO i oO | ! * | | | { | 1 t | ! ( | i ' | w! \ | oO} i \ i] ' ! a, t I 1 I 1 ' ! ! ! ! | ! | 3 Rs, error | ! , | i 1 { t 1 ' 1 | I l 1 \ i i I 1 I ( 1 l \ i f ae Hesse seSceeo nesses ee ee ee hen ee eee OR ¥ 008 09 eI 00g” PLATE XLVII. 34.09: 42.68 FIG. 1 KOMOTAU DAM. FIG. 2 LAGOLUNGO DAM. Scale in Meters on es T TT tf o 2 4 6 8 10 m2 PLATE XLVIII. ooo a uo ie 9 + 2@ 10 S3yuL3W 40 31V9S eect . WG 3dda19 is y= = Tt eo --------—-- QOGI--- --------= > PLATE XLIX, VYRNWY DAM SCALE EVEL _ Hac) -- >> W257 ----------- ComPONENT OF ALLFoR 681-3 TONS S N eS eS ee + ggg Se aes mo eee ee ee nS SH FeoopWaTER Lever. fo---------— 60-81 ---- Kec PLATE L. wars 8 6 2 I HABRA DAM SCALE aE ETRE 0 150 | 2.80 sae __PLATE LI. TLELAT DAM SCALE OF METRES Oe 32. a 6 8 _—i10 SS el PLATE LII. 2.3°4 5 6 78 9 19 a DJIDIONIA DAM SCALE OF METRES 0 PLATE LIM. aieeaiedeieaaeseenedanamneanemmmmadias . GRAN CHEURFAS DAM SCALE OF METRES, oO 2 4 6 8 10 ae! |, 4.00 | ( ee meets PLATE LIV. HAMIZ DAM SCALE OF METRE 7 # PLATE LV. ASSUAN DAM I .0' i al I ! 1. 007. 08 2 re ) WS : R. L. 109. 00 Vg MM Ly : H.W. LRU. 108.00) RR LLY KI H:W.L. OF RESERVOIR R.L.106.00 (7 US = NS CEOS SM, ; Ws TS Dy Wi, Uy iy WA. KE) MMOLE MEI OS E F MMOL 8 KD Noy tig pug Ly fy YN, OT INL oN e BUTTRESS YO OOO ELST a LLL ELIOT py - TEM OIE OLE ALL MLL MAY I TPs TA MAL OIA ELI OE UY Ye IPE UN LEM AMI AAS GLEE LEELA ELSON LLL MEA LLM LO EME MM MLL YL La ew LLL MILI SE ELIOD YOU LI TIED YOO EMA, WG Sy LUM ¢\ LL UIE) MLE AA Or LLM ELE SE ELD WML ALN EEE EL LG GLEE ALE LO LP MOLL LLL YY) UR \S LLL GOEL USO LAL EES We CMM “y WN Wh I Ui Yt Ty Yf Wey A as Wf, LLL LM MUM SE EE Wipro Ci LMM ELLE LILIA . D LEE PA EL LDS : Eee Se ae os seas VOGLER wees AWS NN ON? Vee ao ae LAG F457,2 Bo, i0 as Bes He ye Ee CROSS SECTION OF DAM SHOWING ABUTMENT PIER. ) | POONA DAM SCALE OF FEET O12 4 8 [2 {6 20 i 13.75 5.00 __PLaTE LVI. 75 65 55 50 45 35 25 105 — PLATE LVII. TANSA DAM SCALE OF FEET, 013 5 10 20 ren Pe tyes cms SS wan eee er 56 0 nmr rrr rr 6 gOS Esse es 1 ! I I I i ‘ 1 ' t { ' 1 1 oO aw oO nN, SSS er ' a ! L , ' ' I Be po S cesta, PLATE L VIII. n oe ‘n we ARS S WY - nN SSG va Oo 3 Yd of C = oe d ! d vo G G a: ofS 1 | i. 0 \ ry re? o : | WW wn i | | | 5: aera) & 1 —"* 49 ! oe ! ! ae or ° ” a | -. 4 : | | A uu rn ec a ss Oo. Coe tO Pe | S Oo ' | P sas \ \ Y a ia ae ae ee os y See fs oe a a a 8 4 + | [2] in 3 F y : i : = 4 Moe tt Eee OF M oc A 1 Ow Ou i L Gf o ad 1 i t J a or ,O | af ee, [ ff ep PD we | 4 J ae ae | le hh OR Om OU Rete 38 cot gy & oe P FF FOre1 Fy 2 oe a: ee ee ee ee ee ee a I ' | | \ 1 | { I © “ t | ' | | | ! { | \ ! | es y spe Ny ¥ Vv v 1 e : of iit | MG \ \ ° a in és SS i . z Sa PLATE LIX. 6 8 10 4 SCALE OF FEET 2 0 GEELONG DAM 730 40 Smt 18.50 aoa cdeseescereneas Ns te PLATE LX, 2. | Oni uw || => Cv; cy > 5° he? 5 f olf PLATE L XI. SCALE OF FEET BOYD'S CORNERS DAM 8 \I0 6 4 i! | ee a CONCRETE LEVEL OF EARTH FILLING. RUBBLE & CONCRETE 32.60 35.60 z STREAM :'LEVELI.50 RUBBLE & CONCRETE ROCK PLATE LXIl. 10 ea, SCALE OF FEET oO !234 5 BRIDGEPORT DAM 32.0 PLATE LXIIl. WIGWAM DAM SCALE in FEET 10 012345 ‘ * fe SS ee ee 4 Qa ° 3° S © = ° ‘2 i © r 1 Te A e ” r | Q N ! ' i ! YN! 9 Wl ( 1 1 | 1 | ' 1 Sa Go en ara niente aS S Seat erp Seine Sia a ke Gocmasls ate as oe ro ally H a I i ' a Ka 5 rs a % a ed S i ) = 2 st T oS é ; = ¥ + 9 ie ' ' T I ' pelt 0 oO) ‘ e 2 age ee eke als 6 a ae 8 | ner SR ~ ' 5 ; ; Nie ‘ = *) ' ' 1 tou 5 Q aS i i a i “ os ! : ! MM ‘ s 1 Sp 1 1 ' | : | : | oF Se i : TF I Fi : = a4 | #1 N i i ' oii : = ' ee 4 iG c ' é 1 . 1 1 ‘ ! - ' ~ ! ' It I i 8 } ' ’ ' a ce ! < ' i 1 x 1 ~ ! 9 ba 1 i ! ec ' , . | ! th ae oO # 1 i Pe , es N = - ~ ne | | Sy ! i 9 by 1 i RE i! ' 74 J to! ( AN ae Y © Nes ; ef i ' Oy N ea : \ N 1 ! " ; = & N Mag ‘ = Q = : et ; y ' Koy 3s ae ; zx ‘ ~ it : p ee : hi = Lal 1 ‘ = ~ ! hea | L ‘ 1 : / OF - io Ss . 3 é ° i Q < ee 68E2/ ------ Rows s ees H9Q9] -------> BRS IOS SSS SSE weeds peta iktee Sasa cased aes cs OU9 = 22235225 sede cces notte ease rece en ~-> A—A.LINES DEFINING THE MIDDLE THIRD WATER TAKEN AT 62.5 LBS. PER CUFT. 150 “ MASONRY « PLATE LXIV, SS 2: Ata N eae Lee Vy \ NER KC ITE IED OLELT LILLIE IED SAN MATEO DAM. i gs io < thi y as ES Fees SAY Farrer, KY ie AK os Ar s— Ee ie PECK TREN ROA Sta! KES SSRI RONERONEN SRNR any LL RAK CLS ARLEN RG U Ly TIES NLR EIR 7h ge UA ORI “My Me RRR e Me SRN) a ROR | TORS AN \ hi " Ky OS uy Ni iggy YU ‘WU ATU MY si im Pig Ce ‘S39INIS LIILNG ONOYHL NOILOIS ‘ 4 sous ge (mquoae NY ae AS i SAN HP iuatia Wh WU AO \\\ We ge MW ill: bisa He y TA Lg ‘ AAW AN Wea WS ' \’ UREN \\ SA \ WLM ELLE WY (UN EM LLL LL AUT HE Wy ¥ ‘i Mieih U y yi L as \ NA EEA TS i) AY \\ AN } Te Ly a ae PLATE LXY. rece BEAR VALLEY DAM SCALE OF FEET. \ | [14,91 _ PLATE LXVI. 20 Of 2745 SWEET WATER DAM PLATE LXVII. HEMMET DAM. Protile Masonry Dam = (SB foo nnn == ~~~ nena = non = = ++ ee lo 30" 10 90 70% 50} 30 10 OR -- --- 2 ee eee eee ee eee apg Basnese Channel 7 Section of Fipe and Valve <22in> RUBBLE PLaTe LXVIII. COLORADO RIVER DAM. SCALE OF FEET. oO! 3 5 10 ao | . LOW WATER 0 tt PLATE, LXIX., THE AQUEDUCT COMMISSIONERS EAST BRANCH RESERVOIR MASONRY DAM PRINCIPAL SECTION AT STATIONS 3+15,3+40,4+00 be cee 2 ane uae © monte S x o > ° oY - 2 oe aD wm poe YY bff =, 8.426 YAY ee Yfg YI) , ha 5 F7.2 Profile at A 2Qmites T 68,2 Miles «1 degree. ' ‘ ‘ . ' e ' ’ t a - 24¥y TEE SMe 12 i 7x§.G Rear of Aprons. ao svasespsies 20 6. ke! For-embankment “ a a eeete coed 1 ql u a Top line of Secondary Dam. C fe] 4 — Bond of Stone in Face of Weir "> ~ 4 f Ww 6} 36 PLATE LXXVII CITY OF NEW YORK 197 n b SO . dos 2° s ar) a i) = oO = ru 2 Se eee 8s E og Il 9 ™, 3c Ww é: o§ Bao O we a. a Pw oO $s 5 * Us ags a rid 234 ce co as ae Bem ot Be S38 Ei sl. 2 83 um © Ble 38 2a ZZ a oF Ze w < ao sax Ss oa od es 32 Ke = Je zz « 2D B, 8 e O l,$ 28 wi oo a & & NOTE: 70 91.2 205 78.5 274 PLATE £ XXVIII. or oe eT: QUAKER BRIDGE DAM SCALE oF FEET. 510 20°30 40 FLOW LINE&.206 2793 | “ff ee a pe RIVERBED E.35 ] 1 | | | 4 4531609 LBS. cnts3 ow © : — Dp @ ay 2 / RESULTANT Rt im / WATERPRESSURE)” == 8.20, I 8625 Slice boas 2d 8036 sid 236.531 LBS, 8 / > ij 86l2 | -£+— a ee OC : ati is gui2 © 2 on Di alg ee # Vio ae oe 10 | SESULTANT WEIGH acest ee PLATE LXXIX. PROFILE FOR QUAKER BRIDGE DAM DESIGNED BY BOARD OF EXPERTS. SCALE a) 02039 4 eee THE AQUEDUCT COMMISSIONERS NEW CROTON DAM AT CORNELL SITE CONTOUR PLAN OF DAM NRw croTon DAM REFERENCE O.. Bench Mark. erat. Nigh Wafer Mark | Rock a $.R. Jofm Rock wa. Hard Rock Rot, S$.@.R. Sof Greiss Rock age WGK. Hard Greits Rock ea Sw.n, Sof White Rock wen. Hard White Rock €. Elevation eee © Trench © "Drill Mele mo nig at ALOR sm - RR aa beret ons : MURTUIUT EB MARR aN 3 Mead tare: aR Fr: - = Ee E Tata HWE. fi. aun Lae : fe : iy i E “i i i iB RAH REY : Taran | E a caea 5 Nita BH ARES E MAN: A ah Ra RR HH aa PHT ae RUSE is Rn rH Nan acute ae RS Stk an i nih ea a Cumifim Dap NEW cRoTON DAM PLATE LXXX1. et A A DOOR URW ROU UT dels oe te RE ye NOVI Taio L i 4 Hy PRA 1D) : cee : ae GT Jom nt en etn n nee fe ery er tran De lilas tee alee ae ek a tay Mag 2 eT at tel ete ed eet tT ates el baited ae cdorpl dopeakga ll iol ek tae Uh ket te koed dod CTT eli cll of pelted Pond he heed Lacthethd oo haalde tak det eo Sf ee fT eae ts sa dp t pL gilli Llano label iC yada et gh ll rt poi os et it abl a ot teal Sewer me be prec fe ate [Td ot dye i a eld lad Sahl el ih a ghaglT OoTn eit wk diate Adee lod olde mda . 7: fa ppp daha eke A ped ol hale ee et lta hcl gl daa fi pd phd eodk tld sethead dest cpl athe pl Pep Ped hhc d deh ded td nah nad heap aoael Pnacthce al rd, sold nny cl etal a all called bl diene ad Td Nd ak ld path ol hocgheAd psa A eM ml oe el duel ehh aed ag coheed cei A cach CT ed caked 2 aad gehen ail Duara haa al ecg onda 3 or. ETT al ahd pd sod nel Sey a tet aL f 5 TT cg ape Mee yh ah thal areal yh eth coh Seepage ig A ol i 4 F THE AQUEDUCT COMMISSIONERS NEW CROTON DAM AT CORNELL SITE fee eee en SIGE N s VATION OF DAM. o 20° 4 60' SCALE ames PLATE LXXXIl. = QO ”| Ee a) O38 ko ous or < One) z= ok LJ za TH AT SA ws = AAR a \ ANY B\\\E MQ QQOds KK ue : WS t N\A o fi : $ + VE 1 4 poe 2 - o \ PO Ny ‘ AX KARR RRR RRA QV OO } SAN SEER Ne : 3 6 » SSSA ‘ i = Eh’ gh aly, eh Sr. =p Myc: vy ey Bh PLATE, LXAXIM, on ZA MINIMUM SECTION MAXIMUM SECTION OF OVERFALL . SH - Ho ——75 TO 80 —=._—_ THE AQUEDUCT COMMISSIONERS NEW CROTON DAM. AT : CORNELL SIT Nova. THE WIDTHS OF THE SPILLWAY CHANNEL MAY BB INCREASED OURING CONSTRUCTION, IF POUND NECESSARY, OWING 70 THE NATURE OF THE MATERIAL ENCOUNTSAEG Om OTHEAMER ELE. 150. 4 + Vox 4 2 EX Xt 7 SNe w x We ARE LE REE NS x INTERMEDIATE SECTION PLATE LXXXIV, | K- 22.516" 9 esa SSS ee \ E1395. Full Reservoir _ EEE ci ee a pie | 08 6 Ral “ | = it er Sy a | aoe Se | ¥ il a Bt gf 5 El.+ 90 | aa pn oe S366 | E1350 ____ fe aot — we et 80, Kull Reserva / | | SSS = 7 e | a te | a i af | oh yy | Ae | sy 3 97 | # 3 , ae J | / | EA | —~ ———— —a1.494— — —__\ Finished Surface ly 7 | w+ 27.81 tare, Ses oe %, | a ! Osnee—s: =G: “av oS ~-Os son wD | eer s O Re T | = Original Surface of Earth _ 2 Ya hes / | aa Osis Sikes , —— —— —— —— —— - 114,95 - —- —- —_ . | Foret ole rage eg es | | | | : Qe | 4 INe | | Le ON. | 1 ger “4 “o | | s *& | | | Portland Cement Mortar "® | . Zp | ¢ S anes ; a : Ys | ee ee ae er ne ( {8 : MS nee ee os ANI DONTANIN CT VING LAW Me > / VA. —ANX WYWY Ix WV ILKCGIN V7 IK, I GY, Iie * WAIN] NN ax MN N DS Gay j Se pe a eg a ee SPIER’S FALLS DAM. WACHUSETT DAM. Fig. 2 Fig. 1 PLATE LXXXV. RE ae c 4-48 nh fa ee ae ee a8 (Cena aon aaERRES 8 raga 2 3 8s fneting masdury under es temporary head house at 7d _of small fuse y CaS SECTIONAL ELEVATION XX ‘ WOOK ee EXTENSION OF hyo WACHUSETT AQUEDUCT ; WQG MG GB aes Ee es ppb ore i y wl 4 wl z ° ra Sand Sump - mE ie Op B wn re ST Monnbie a : yo By lectatigsh — 48° talve d oO Brackets fo Sc . ao 2 Poor Pronk) § J SECTIONAL PLAN DETAILS OF UPPER GATE CHAMBER, SECTION OD Dosh: tines indicate end of existing masonry on side nest to dam ond EL 300 Lao f. Yi dotted lines, on opposite side | 1 | Overflow EL 292 25 pe sesee H rough SECTION BB! _ EXTENSION — OF — = _ WACHUSETT AQUEDUCT; Te a — 2 el CL 78452 Uae ae " fs ct a i m Turkine sere = . pripigehe re nip te iNeed ELS SECTIONS AND PLAN OF LOWER GATE CHAMBER, Li of Crest 2595 Class B Paving a Fountain I~ avr ven cere reRRER et el 2859 - i —— No paving on eae ee bottom of channel @ + ELEVATION OF UPPER GATE CHAMBER. HALF SECTION FF fo vertical SECTION OF DAM SHOWING GATE CHAMBERS. z ‘ at H ry Le if hervzontay TNS GATE CHAMBERS FOR WACHUSETT DAM. METROPOLITAN WATER SUPFLY, BOSTON. Frederic P. Steams, : : oe M. Am. Soc. C. E., SECTION PERPENDICULAR TO LINE OF DAM ON CENTER LINE OF POOL ; : SECTION EE | OVERFLOW POOL AND. CONNECTIONS. Chief Engineer. EWLAROED SECTION OF LIRR §N ws PLATE LXXXVI. oe eee 1, 310.25 | Scuttle | Hea 58”Stcel Pipe 4"thick BOONTON DAM Scale in Feet 1 T 20 30 40 48"Steel Pipe 4” thick Gy) —\IN x ZY SZ ~- Omen e is MAXIMUM SECTION OF DAM PLATE LXXXVII. FIG. 2— OVERFALL SECTION OF SPIER'S FALLS DAM. PLATE. LXXXVIIL I 20> ea 01! 2’ - Cf El-+ 230 1 | 7 a“ ee 1 | yo g wo Eiti70 [ gue 4 El + 152.24 I E = : 5 ots é = fea) Fia. 2 Rad.= 399,89! | 18>] | El+221 ROOSEVELT DAM El--217 = 190—=1 .. T El+ 170 Elst 150 & S Ma Elst 130 - | 166,33 — — | py ie) | LAKE CHEESMAN DAM; WVd ANOHSOHS WV YSQNISHLVd V2 ANY AM 5 . 9909 TH WAM ae —e = E= MIVA a Diss ~ FL QT 0g9e “TH EAM: Wl Mz ——0i— -- Pua ces “1d ped meals Ft TS Tal 2a PLATE LXXXIX. OL69 “1H Ter ; ah 0.8 * v parte pa= DEH moe: | : 210-— i | it ale BE Mt ni | Hi Hf ext i Ac Ne C ® 3 2 gd g a , 3 PLATE XC. Wvd JO NOILDIS WNWIXYN YIOANASAY Y3AAIN SSOUD yoog JooTeog 02 9T GE 8 F O SYA8WVHO-3SLVD HONOYHL WY 4O NOILD3S op Le a BOE WWD au} ee ADO iS ie iy qo Se oe |) is Le a iS & ie Go i WU UY Owes Gy G7 7 Us ae ae ay a7) VAY Ce SY = A ertical le SS. So} ee Me Me a oo Le Le d By . A ioy oT Ue. 4 4 Ms 3 a TEM UrezaNg uy C 4 Ae H Downstream Gate-Chamber a be soujang Pasodosy z 0 t og Joatwog dOLl 4O NOILDSS G3DYVINS I 1 sousANg juosoly a 2 oe ne ie ae a 2 = PA oe roy Ce Ome cf ‘ ro Oy oc me AN a ‘1 Bek OL? ie RM aL aU C/T RNS sh Ws he Met Boo SD) are Apa 2 5 * : 2 oy ---70,1I-----| i —90,8-- >| -59,8- -— 4 | ae fu Qo Te 1 pty mn 7 2 os 58 ak = oF g~ 5B? a: PLATE XCI. 167" Reseryoir__ E1,310 , a Full SCOOELTTEETTT =| 3 Tr = WL. WO ORI OF = - Fe ENLARGED SECTION OF TOP, Eo O>y=7" Scale of Feet ois 7 g 2 Concrete Gutter toe { . 90, |100'3'to center.of Fountain Dy: HOM: Bale 1EZIENS SECTION OF DAM THROUGH GATE-CHAMBERS. Scale of Feat 8 19 8B CROTON FALLS RESERVOIR. PLATE XCIL WATER. SUHPLY or TOWNS. INLET TOWER Section ficie. FIG.S. Sestiory of Brbankment at Gangway and Inlet Tower BOMBAY WATERWORKS. PLATE XCIII. LIVERPOOL CORPORATION WATER WORKS. YARROW RESERVOIR. z S. ‘ Top Bank fh 6 i a 66.0 15.0. 66.0. i a ane __ fon Water mf VE eereccee m: Embankment Embankment of Ground face Swe ALAN A Beg=—— OT ro ! itm as ~~ Fs re ie. “Mas b Per as aor 22s Pkard. if ss Stones > > TURNERS EMBANKMENT Scale 40 Feet to ar Inch. 4 Z e ‘ at SSS Wa PA matorssaac 1%, . lo* *'@ ng San (2 ‘5 % “4 3 ee iy Gescaty tere } ts. (ch, ' i he fas as “Si Nj i Sa a Me wid # fake. . sR i oy YY) x “> SS S we ON ISL a y 1, “Ys <= Ss MY, CN oS; RC aN 4 Nyy Y,, SS QM oe te YS . eK Mie: V4 S WN Ne Q ee ww ZENON) US WS WS Sa ms ~ M4,» Ure USK S LES Seat B90: O06, aes Tare Ore DETAI L OF ROADWAY A _—— _—— ed ace — ee ee eo — ee ee ee 4.87 ik Ml SECTION B-B —— aos Gee cee, _—— NS? aM uv 18 Collar Bo ft. EE Stops UNV =YNWw! x Road wa y WH NG) NSN »! SY Wee = Miz Wh Mie Myre Mee MYM —INY/ YY, YA) mi i \\ SECTION THROUGH NORTH CONDUIT TIS q < = STIS INN Leta NS CG INN Wz ZU ANMIN S Hl SIDI iS SY e * G - AY ccna WILY Ax IWIN : Soe : Oe gS EE ae pres Eu a are ii Ya teu WSs Ys BELLE FOURCHE DAM, SOUTH DAKOTA. CRIB DAMS. Ne1. OLD DAM AT PLYMOUTH. N92 7. COLUMBIA DAM, SCHUYLKILL NAV. CO. Across the Susquehanna River at Columbia,Penna., as built by the Phila. & Reading R.R.Co.[lessee of Susq.Canal,] in 1875. Oe ae (OA TA OA TONAL NS SSE EZ SETI. est = E SS oe a == (J ZZ-”= eZ“ = pe aS xe cm Ran = SS SS SS fi Se Sia ae Bele at ! Ne 2. DAM AT POPLAR NECK. = eZ MN" ":.-. oe “ i SCHUYLKILL NAV Co SSS SS SSS SS" eee Ea WE TA a ae ‘ le CEE WY by EZ cs a ; e ae +¢ Fe a8 ee as He = SS eS SE fe ha ae oo ee | i i hj Za cele | - i He i y Nes. FELIX’S DAM wa f----6 N°3. NEW DAM AT PLYMOUTH come - 6.50 SYeltank ere SCHUYLKILL NAV. CO. ‘287% 32° beng te hee ——] TE es : = 140 ar LF ee 5 LZ ZZZA SS BZ SNS EH RE ae Ror roa A — —_ co > y SECTION THROUGH THE UPPER SLUICES. ROCK BOTTOM =z e = 222 PLATE XCVI. SS a ee SS CRIB DAMS. T PLYMOUTH. LL NAV. CO. LEZ ZZ egg — SS cs ‘Nc + Bae Ng - > > oe . CLAY * ee . r | AT°“POPLAR NECK. oe te ee ae ae eg SHUYLKILL NAV Co. SSS 2 ae, Ske OHS Oa aS VME ML . Be em a ae Ss < A Pie er PS LS > ie ee eee a Yo AL uni ROE STD RENE HA SECTION THROUGH THE CENTER, 5 x ns JAM AT PLYMOUTH CHUYLKILL NAY. CO. RG ie er =a $e 5 ay ae a oS LS Se SN Re LOW WATER ICK BOTTOM Sar neo4, VINCENT DAM. SCHUYLKILL NAV, CO. — oe eS 5 0 es x See a SECTION THROUGH THE UPPER SLUICES. Sy 6 = ™ STIS Ey . no6. KERNSVILLE OAM. CROSS-SECTION SHOWING RELATIVE POSITION OF OLD & NEW DAM & ABUTMENT, Coss Loe SSS eA SRI | oo ra i : ‘ aft - | i t mi 3 no X lm : a { = ° : Zz { ° n Oo > = "WVG JO NOILOAS SSOHD f ‘DIA Mee ‘NVG NS0GOOM G10 SO NOILOSS *t “DIS ‘AVd AMXOATOH PLATE XCVIII. Rs ae een a g d a 1 1 ou 12 Do eo she Bos a 2 2 3 2 py 3 A Hs | Ke gs 3 3 W o a ‘ e a MN a a a fa x 22) 220] ayy] sy] i] ty) oy) 8) Ag) oy a) 5 2 x 7 il io 8 7 6 5 LN (Bracing “d" shown AT in broken lines 5m : TIRANA SA Section Showing Inetined Bracing “b” and “d” Ash Fork, Arizona Section Showing Vertical Bracng“a™ 21 19 17 15 18 11 7 5B 8B 14 BS Fic. 1—Elevation of Upstream Face. Section Showing Inclined Bracing “ic” Benn nang ennne TSS mSa se mrsesnse Ss csesSess Sess Ssas ena eaten ee 6%-4%--—-—- —--------~-------~-~-~~-------~-- | PL2Ixigxs’61g ‘ PL2ixigx1’9" 7]_ 201 Beam 65 tbs. Fig. 2.—Diagrams Showing Lateral Bracing. Bracing a, b, c and d, is Longitudinal Bracing connecting the Bents, and lying in the plane of the members indicated. ae Py 7 Bent/PL___ > -_-_-_--. fee eoe besa ahs : ae * / *Bent Piadhigia’ioy § ao > eee 1 7 ae s! |e By Ven PA of |= a af Le BENTS 1 TO 7, Ry 4 8 BENT 24. f ® : 19 2 “i 3 TG \ ie BENTS 8 AND 9; Vy x 7 "220 23, ! 3B ho PER ry ee NR ' 3 q 1 ' ! a” BENTS 10T0 12; 0 Sons “19° 2t, yer Yr hn ae BENT \% re (pale Fig. 4.—Arrangement of Bents, a recor . x PL.2ax54x2' . El. 42.50 4h Fic. 6.—Section of Masonry Abutment. Fie. 3.—Details of Bent No. 15. Bed Rock: PLATE XCIN. STEEL DAM AT REDRIDGE, MICHIGAN. Railway Trestle ES Arash, Railway Trestle ~~»: - A Hi E1.84.0 / if iv | ior. 1 } Od % | I at It —) 1; a gas. ater eh a | i * = 2 2 | 122,000 ' Mx SECTION MEAR ENDS : FIG. 4 4 ss Yisi.28.921 CROSS SECTIONS OF DAM He SQN é 4 a oO ge > ‘i 601,000 | | ] | 3 SECTION NEAR CENTER ee a pe ene Fee nl en aN oe Sah Sk gy! ope = -- - --- gx’ - ---- we GE MEL G Rie me = aoe = rhe g24------ “a | I SS ae 7 ' ; 4 i Mee 1 ve» a SS % ey a Fre 2 et ' 1 25) tae 33 va = al eee ae Bo tea Crest Line 1 |! 2 Gacwa - e t+ BH —# th 1 = iS Core Wall | = ' Lit ye a =. Drie ' i Jo 2 ee al 5] Lt ra ty Pepe tet ee ee Pe ae oo 2+— -— 3 1 = ae q Heo 3 s] : : Ee Oesse Sts afe= OG! ae meee, vl : = Launder Base of Rail E1 91.0 E.90.25 EL.85.0 E1.85.0 F1,90.25 | i | r Le fa AT, | 3 \ | NIZE er Tish roel [7 = 60 ae TTT OAT TTT, “ oe 52 “UT to jo aa, hI | 44 ar Davide y 36” 28’ Vertical Dash und Dot Lines A +28" Yt , 207 Indicate the Bents of the Trestle Dake Sila ee 12” SS ee oe ee ee 4 , 4 EIT TTT TPT TTT ETT TTT TTT O” ‘20’ 40" Go” 80" 100’ 120’ 140’ 160" 180” 200’ a0’ ato’ a0’ 280" 300” 320’ gio” 300’ 380" 400” 420" du” atu’ ago! DOWN STREAM ELEVATION FIG.3. PLAN AND ELEVATION OF DAM. PLATE C. STONEY ROLLER SLUICE GATE FOR BEZNAU DAM, SWITZERLAND. ELEVATION VERTICAL SECTION FROM UPSTREAM FROM DOWNSTREAM Counter> ight Ss wel END ELEVATION == SERVICE BRIDGE VERTICAL SECTION 4. NT. 0%89: 0201+ — 0001I_—>«— 002 —>}< — 0008 + — 008 > — 008 >} 00 ec OSGI. ae 08 — > —— 91 — Sy im dvb 13 3 a — OF 166 069+ a ones t 4u 79404 ~onuRegie |. FT ee) v “ av so/v/Ao ‘ Av 80/81/10 }<————1400- VERTICAL SECTION c-D rn oyoshs 73 THROUGH ROLLER SECTION PLAN OF ROLLER _— PLAN OF SERVICE BRIOGE 2300441 5004 HORIZONTAL SECTION E-F THROUGH ROLLERS Ly Li Ui iflday Mie Zh 7G Ge TS Ke us Zi ZA ASS LW = Z me SS -—= ---— HH ly ~ am we = a = ae “2. TEN Relate atte cee c -_ —— “# = F ee ; inate ee eT ee A ic ll a ee “ o Saas . Pies 2 Se a a re ge «