Earthquake Response of Concrete Gravity Dams Including Base Sliding

Abstract

The stability of a concrete gravity dam against sliding along the interface between the dam base and the foundation rock must be assured in a seismic safety evaluation. The hybrid frequency–time domain procedure is used to compute the earthquake response of gravity dams, including base sliding. The procedure accounts for the nonlinear base sliding of the dam and the frequency-dependent response of the impounded water and the flexible foundation rock. A parameter study of typical gravity dams shows how the earthquake-induced sliding is affected by the characteristics of the ground motion and dam system. Based on the results of the study, it is necessary to include the effects of dam–foundation rock interaction to obtain realistic estimates of the base sliding displacement for a dam. The sliding displacement is sensitive to the value of the coefficient of friction for the interface zone, especially for moderate to tall dams. Water compressibility also affects the base sliding displacement. Although a dam remains stable after an earthquake, the base sliding deformation may damage the interface zone without a significant isolation effect for the dam body.