KONG Xianjing, ZHOU Chenguang, ZOU Degao and YU Xiang

Abstract: The height of several rockfill dams in China has exceeded 300m with tremendous volume and weight, and the length of dam-foundation interface is over thousand meters along the river. In addition, since rockfill materials have nonlinear property, the influence of dam-foundation dynamic interaction during earthquake causes attention more and more in the engineering,and is necessary to study systematically. According to the several representative high rockfill dams constructed and awaiting construction in China, the wave analysis method is adopted to consider dam-foundation dynamic interaction and study the influence of intercepted range of foundation on the dam dynamic response. Through contrasting the results of vibration analysis and wave analysis, the influence of the dynamic interaction between high rockfill dam and foundation is discussed. The results indicate that the dam dynamic response calculated by wave analysis method conforms to reality better than the vibration analysis method,and suggest that the intercepted range of foundation is equal to 0.3 to 0.5 times of the length of dam-foundation interface along the river. In other words, the range is about 1.0 to 1.5 times of the height of dam for the concrete-faced rockfill dams, and the range is about 1.2 to 1.8 times of the height of dam for the core-wall rockfill dams. Compare with the results of vibration analysis method, the acceleration extreme values of dam calculated by wave analysis method decrease about 10%~40%, the dynamic displacement extreme values of dam decrease about 10%~50%, and the dynamic stress extreme values of concrete face slab decrease about 20%~40% (tensile) and 15%~30% (compressive), respectively. Therefore, the influence of dam-foundation dynamic interaction is significant,and the vibration analysis method will overestimate the dynamic response of high rockfill dam to underestimate the seismic capability.

Keywords: dam-foundation dynamic interaction; high rockfill dam; vibration analysis; wave analysis; intercepted range of foundation