Dynamic effect of sediment on dam during earthquake

Dynamic response of reservoir sediment is investigated by a model of poroelastic medium. The pressure wave equation is solved numerically with the momentum equations, and they are coupled with the pressure wave equations for the impounded water and the finite element model of a concrete gravity dam. The dynamic interaction of the impounded water and sediment is sensitive to the inertia effect of the sediment which can be characterized by the sediment thickness and the porosity. The latter alters also the speed of pressure wave in the sediment. The gas absorption in the pore water reduces the first natural frequency of the reservoir. The sediment could augment significantly the hydrodynamic pressure on the dam.