This research project will focus on detailed field measurements and response prediction analyses of another large arch dam in China, to study dynamic interaction mechanisms of the impounded-water, sediment, and foundation rock with the dam. New areas of investigation include the dam-water-sediment interaction effects with respect to the sediment properties and sediment thickness, effects of canyon topography on the free-field ground motions, and improved dynamic excitation techniques. The basic concept in the field measurements is to excite the dynamic response of the dam and its retained water by detonating explosive charges. Two types of explosion tests will be employed: those applied to the foundation rock and those detonated in the lake water. In addition, two approaches based on the seismic reflection and refraction techniques will be employed to measure the reflection coefficient of the lake-bottom materials. The proposed test program will provide improved understanding of the actual dynamic response behavior of arch dams influenced by the interaction with the impounded-water and the foundation rock; by the energy absorption of the lake-bottom materials; by the lake topography; and by the spatial variations of ground motion around the canyon. Results of the proposed research should lead to better understanding of the dam-water-sediment and dam-foundation interaction effects, and will provide measured data by which the accuracy of computer programs for analyzing the earthquake response of arch dams can be examined and possibly improved.
