Dynamic Behaviour of Sediment Deposits in Front of Concrete Gravity Dams

Analysis of dams is a complex problem due to the dam-reservoir-sediment interaction. An important factor in the design of dams in seismic regions is the effect of bottom sediment forces on the face of the dam as a result of earthquake ground motions. For an accurate analysis of resultant sediment forces on the dam, the sediment is represented in a fluid-filled porous solid on the basis of the Biot theory. In Biot formulation, the equations of motion of the soil mixture are coupled with the global mass balance equations to describe the realistic behavior of sediment. Because of irregular geometry, the sediment is generally treated as an assemblage of finite elements. The weighted residual standard Galerkin method with 8-node elements is used for developing finite element code. The analysis is carried out in time domain considering earthquake excitation. Newmark time integration scheme is developed to solve the time-discretized problem which is an unconditionally stable implicit method. Finally, the seismic behavior of sediment due to ground motion is investigated.

Keywords:

Gravity dam , sediment , finite element , earthquake , interaction