Generation and Dissipation of Dynamic Pore Water Pressures in Gravel Shell Embankment Dams by Finite Element Method

Abstract

Dynamic pore water pressures induced on gravel-shell embankment dams by earthquake motions are studied by means of a computational scheme based on a two--step decoupled procedure. In Step I, a static and dynamic stress analysis is performed with standard finite element techniques accounting for non linear soil properties. In Step II, pore water pressure increases are evaluated based on: i) static and dynamic stresses obtained in Step I, and ii) laboratory cyclic triaxial
test results performed in undrained conditions. Finally, dissipation of pore water pressures during the earthquake is evaluated as a function of time through a finite element solutioo of the diffusion equation.
A numerical example illustrates the actual significance of the dissipation process in the ma9nitude and distribution of pore water pressures induced by earthquake motions, and safety factors in postearthquake stability analysis.