Seismic input method for a gravity dam–reservoir water–foundation system considering the compressibility of water

Abstract

The compressibility of reservoir water and the propagation of seismic waves in reservoir water are often disregarded in the seismic input of gravity dams. This paper proposed a method for solving the mixed wavefield of a reservoir water–dam foundation site on the basis of the wave equations for elastic solids and compressible water media. The radiation damping effects of the infinite foundation and reservoir water were simulated via viscoelastic artificial boundaries and fluid medium artificial boundaries, respectively. The dynamic interactions between reservoir water and dams and between reservoir water and foundations were simulated via the acoustic‒solid coupling method. A seismic wave input method for a gravity dam‒reservoir water‒foundation system based on both solid and fluid medium artificial boundary substructures was proposed. The seismic response of a concrete gravity dam was analyzed via the proposed seismic wave input method and the conventional seismic wave input method, which does not consider the propagation of seismic waves in reservoir water. Compared with those of the method proposed in this paper, the displacement and stress calculated via the seismic wave input method that does not consider the propagation of seismic waves in reservoir water are greater, with a maximum increase of 13.6 % in displacement and 55.9 % in stress. The minimum safety factor for antisliding stability of the dam foundation surface is relatively small, with a decrease of 13.8 %. The seismic wave input method that does not consider the propagation of seismic waves in reservoir water overestimates the displacement and stress response of the gravity dam and underestimates the safety factor of the antisliding stability of the dam foundation surface. Therefore, adopting a seismic wave input method that considers the propagation of seismic waves in reservoir water is necessary for the analysis of the seismic interaction of the gravity dam–reservoir water–foundation system.