Abstract ........................................................ 1
Introduction .................................................... 1
Background ................................................... 1
Presentation of Data ......................................... 2
Sources of Information ....................................... 3
Summary of Data .............................................. 3
Selected Case Histories of Dams on Landslides (by Landslide
Type) ........................................................... 4
Rock Fall (Including Talus Deposits) ......................... 4
Slides in Competent Rock ..................................... 6
Slides in Incompetent rock .................................. 13
Massive Rock Slides and Glide Blocks ........................ 13
Earth and Debris Slides ..................................... 15
Rock and Debris Avalanches .................................. 16
Debris, Mud, and Earth Flows ................................ 17
Cambering and Valley Bulging ................................ 22
Problems Encountered Due to Interaction Between Dams and
Landslides ..................................................... 22
Abutment and Foundation Instability ......................... 22
Abutment and Foundation Seepage ............................. 24
Mitigative Measures ............................................ 25
Planning Measures ........................................... 25
Avoidance of Landslides .................................. 25
Relocation of Site .................................... 25
Site Abandonment ...................................... 27
Redesign of Dams Because of Landslide Problems ........... 27
Lowering Reservoir Level or Reducing Rate of Filling ..... 28
Physical Measures for Foundation and Abutment Stabilization .... 28
Removal of Landslide Deposits ............................... 28
Total Removal of Landslide ............................... 28
Partial Removal of Landslide ............................. 28
Partial Removal of Talus Cover ........................... 29
Partial Removal of Landslide Deposit Following
Construction or Postconstruction Slope Failure ........... 29
Flattening Abutment Slopes .................................. 29
Earthfill or Rockfill Berms Serving as Buttresses ........... 29
Dam Serving as Buttress ..................................... 30
Cutoffs or Keys ............................................. 30
Retaining Walls ............................................. 30
Piles and Caissons .......................................... 30
Anchors ..................................................... 30
Moving or Reinforcing Spillway .............................. 30
Guniting .................................................... 31
Dental Work ................................................. 31
Physical Measures for Reducing Abutment and Foundation
Seepage ........................................................ 31
Impervious Cutoffs .......................................... 31
Impervious Curtains, Membranes, and Blankets ................ 31
Drainage Systems ............................................ 32
Multiple Mitigation Methods ................................. 32
Breaching as a Remedy ....................................... 32
Summary and Conclusions ........................................ 33
Acknowledgments ................................................ 33
References Cited ............................................... 33
Appendix ....................................................... 51
Figures
1. Original sketch map and cross section showing landslide
conditions at Farmers Union (now Rio Grande) Dam,
southwestern Colorado, United States ........................ 2
2. Photograph of Mammoth Pool Dam, San Joaquin River,
California, United States ................................... 5
3. Cross section through the narrow gorge in the foundation
of Waterbury Dam, Little River, Vermont, United States ...... 5
4. Views before and after construction of Taylor Park Dam,
central Colorado, United States ............................. 6
5. Gross Dam, Colorado, United States .......................... 7
6. Gravity-slip surfaces in granitic foundation rocks at
Gross Dam, Colorado Front Range, United States .............. 7
7. Photograph looking upstream at the remains of St. Francis
Dam, southern California, United States ..................... 8
8. Cross section through the 1928 left-abutment landslide at
St. Francis Dam, California, United States .................. 8
9. Cross section through the pre-existing rock slide that
forms the left abutment of Beauregard Dam, northwestern
Italy ....................................................... 8
10. Simplified cross-valley cross section through Dalešice
Dam, Jihlava River, Czech Republic .......................... 9
11. Oblique view of Tablachaca Dam, Peru ....................... 10
12. Photograph looking upstream at the right-abutment
landslide at Tablachaca Dam, Peru .......................... 10
13. Map of rock slide at the right abutment of Tablachaca
Dam, Peru .................................................. 10
14. Photograph of Lake Harriet Dam, Cascade Range, Oregon,
United States .............................................. 10
15. Major Holocene landslide deposits in the Columbia River
Gorge, Washington and Oregon, United States ................ 11
16. Oblique aerial view of Bonneville Dam in the Columbia
River Gorge, Washington and Oregon, United States .......... 12
17. Map of the Cascades landslide complex and its components,
United States .............................................. 12
18. Simplified cross section through the rock slide in schist
that forms the right abutment of Durlassboden Dam,
Austria .................................................... 12
19. Photograph of Fruitgrowers Dam, western Colorado, United
States ..................................................... 13
20. Locations of 18 dams on landslide bench and slump-block
landslides derived from the basalt plateau of the Grand
Mesa, western Colorado, United States ...................... 14
21. Photograph of Grand Coulee Dam, eastern Washington State,
United States .............................................. 15
22. Cross section through the Parangana Dam site, Victoria,
Australia .................................................. 16
23. Oblique aerial view of Cheakamus Dam, British Columbia,
southwestern Canada ........................................ 17
24. Cross section through the site of Cheakamus Dam, British
Columbia, southwestern Canada .............................. 17
25. Aerial-oblique view of Mud Mountain Dam, western
Washington State, United States ............................ 18
26. Cross section through the site of Mud Mountain Dam,
Washington State, United States ............................ 18
27. Aerial view of Swift Dam, Lewis River, western Washington
State, United States ....................................... 18
28. Geologic map of the area around Swift Dam, Washington
State, United States ....................................... 19
29. Geologic map of the area around Yale Dam and Yale Saddle
Dam, Washington State, United States ....................... 20
30. Sketch of the earthfill sediment-retention dam on
the North Fork Toutle River, southwestern Washington
State, United States ....................................... 21
31. Photograph of Medeo Dam, a debris-flow retention
structure on the Malaya Alma-Atinka River, Kazakhstan ...... 21
32. Photograph of construction of a cellular reinforced-
concrete debris-retention dam on the Bolshaya Alma-Atinka
River, Kazakhstan .......................................... 21
33. Cross section through B.F. Sisk (San Luis) Dam,
California, United States .................................. 23
34. Photograph of Cheurfas Dam ................................. 23
35. Photograph of Star Mountain Dam, southeast Oregon, United
States ..................................................... 24
36. Oblique-aerial view of Ochoco Dam, central Oregon, United
States ..................................................... 24
37. Cross section through the site of Howard Hanson Dam,
western Washington State, United States .................... 25
38. Photograph of Scott Dam on the Eel River, northern
California, United States .................................. 26
39. Cross section through a narrowed section of the Romanche
River valley, France ....................................... 27
40. Oblique view of the left end of Mojave River Dam ........... 29
41. Photograph of the remains of Mystic Lake Dam,
southwestern Montana, United States ........................ 32
Tables
Appendix Table A. Dam characteristics, relation to
landslides, mitigative measures, and cited
references ................................... 51
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