ILLUSTRATIONS.
| PAGE | ||
| Fig. 1. | Longitudinal Section of Yarrow Dam Site | [10] |
| 2. | Cross-Section of the Yarrow Dam | [10] |
| 3. | Plan of the Tabeaud Reservoir | [17] |
| 4. | Tabeaud Dam: Plan Showing Bed Rock Drains | [18] |
| 5. | Details of Drains | [18] |
| 6. | View of Drains | [19] |
| 7. | North Trench | [20] |
| 8. | South Trench | [21] |
| 9. | Main Central Drain | [21] |
| 10. | Embankment Work | [23] |
| 11. | Dimension Section | [26] |
| 12. | Cross and Longitudinal Sections | [27] |
| 13. | View of Dam Immediately After Completion | [29] |
| 14. | Cross-Section of Pilarcitos Dam | [34] |
| 15. | San Andres Dam | [34] |
| 16. | Ashti Tank Embankment | [35] |
| 17. | Typical New England Dam | [40] |
| 18. | Two Croton Valley Dams Showing Saturation | [41] |
| 19. | Studies of Board of Experts on the Original Earth | |
| Portion of the New Croton Dam | [43] | |
| 20. | Studies of Jerome Park Reservoir Embankment | [46] |
| 21 to 24. | Experimental Dikes and Cylinder Employed in Studies | |
| for the North Dike of the Wachusett Reservoir | [49] | |
| 25. | Cross-Section of Dike of Wachusett Reservoir | [49] |
| 26. | Working Cross-Section of Druid Lake Dam | [53] |
| 27 to 29. | Designs for the Bohio Dam, Panama Canal | [55] |
| 30. | Cross-Section of the Upper Pecos River Rock-Fill Dam | [59] |
| 31. | Developed Section of the San Leandro Dam | [59] |
EARTH DAMS
CHAPTER I.
Introductory.
The earth dam is probably the oldest type of dam in existence, antedating the Christian Era many hundreds of years. The literature upon this subject is voluminous, but much of it is inaccessible and far from satisfactory. No attempt will here be made to collate this literature or to give a history of the construction of earth dams, however interesting such an account might be. The object will rather be to present such a study as will make clear the application of the principles underlying the proper design and erection of this class of structures. In no way, therefore, will it assume the character or dignity of a technical treatise.
Dams forming storage reservoirs, which are intended to impound large volumes of water, must necessarily be built of considerable height, except in a very few instances where favorable sites may exist. Recent discussions would indicate that a new interest has been awakened in the construction of high earth dams. As related to the general subject of storage, it is with the high structure rather than the low that this study has to do. To the extent that “the greater includes the less,” the principles here presented are applicable to works of minor importance.
Many persons who should know better place little importance upon the skill required for the construction of earthwork embankments, considering the work to involve no scientific problems. It is far too common belief that any ordinary laborer, who may be able to use skillfully a scraper on a country road, is fitted to superintend the construction of an earth dam. It has been said that the art of constructing earth dams is purely empirical, that exact science furnishes no approved method of determining their internal stresses, and that in regard to their design experience is much more valuable than theory. When the question of stability is fully taken into consideration, it certainly requires a large amount of skill successfully to carry out works of this character.
Extreme care in the selection of the site, sound judgment in the choice of materials and assiduity in superintending the work while in progress, are all vitally essential.