Ageing dams located across the west coast of North America, both in the USA and Canada, are threatened by potential for large earthquakes. Assessing the seismic performance of these dams has been a challenge. This paper presents a synthesized approach for assessing the seismic and post-earthquake performance of a dumped rockfill dam built in the 1960s with a gunite (shotcrete) face as the water barrier. The dam may lose its freeboard due to seismic settlements. If loss of freeboard does not occur, the gunite face can still crack and allow leakage. Excessive discharge at the downstream toe due to the through-flow may cause the rockfill at the toe to unravel. Such unraveling and consequent sloughing of the slope may cause a dam breach. The synthesized approach consists of a dynamic analysis and methods for assessing the cracks in the gunite face, leakage through the upstream face, and potential for unraveling and instability of the downstream slope.
Thavaraj, T, and Stevenson, G. 2020. “A Synthesized Approach for Seismic and Post-Seismic Performance of a Dumped Rockfill Dam with a Shotcrete Face,” in Proceedings of Geo-Congress 2020: Geotechnical Earthquake Engineering and Special Topics, Minneapolis, MN. Hambleton, J., P., Makhnenko, R. and Budge, A. S. , eds. ASCE G-I Geotechnical Special Publication (GSP) No. 318, pp. 20-29.