Report on Seismic Stability, Onondaga Dam, New York, Attachment Number 2,
CORPS OF ENGINEERS BUFFALO NY BUFFALO DISTRICT
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The Onondaga Dam is located in a region of exposed gentle, southerly sloping Lower and Middle Devonian limestones and shales of the Helderberg Group, Onondaga Limestone and Hamilton Group. Superimposed on the dip are some minor, small faults and folds of Late Paleozoic age. Therefore, the dam is situated in an area that is structurally simple and tectonically stable. The dam is located in an area that historically can be described as nearly aseismic. To obtain qualitative and quantitative data for use in the assessment of the stability of the dam under earthquake shaking, three test borings were drilled from the crest of the embankment into the foundation soils. The static stability of the embankment and foundation soils is adequate based on the type and relative density of the soils present and the geometry of the dam. Likewise, the stability of the concrete spillway, which bears on rock, also appears to be adequate. As a result of the analyses conducted, it is concluded that a more in-depth analysis of the stability of the dam due to liquefaction of other earthquake effects is not warranted.
- Soil Mechanics
- Civil Engineering