Seismic Sliding Analysis of Sandy Slopes Subjected to Pore-Water Pressure Buildup

Abstract

Pore-water pressure buildup strongly affects seismic permanent displacement of the slopes constituted from saturated soils. Previous attempts simulating the generation of excess pore pressures (or decrease in soil strength) have been applied in the sliding block models, but the models assumed a rigid block. In the present study, a simplified procedure is presented to account for this effect in sliding block analysis. A correlation between excess pore pressure ratio and cumulative absolute velocity is obtained through the fully coupled solid-fluid effective stress analysis of level ground. The effect of pore-water pressure variation on critical acceleration is investigated in this paper, and the available Newmarkian sliding block methods, such as the rigid block, decoupled, and coupled approaches, are modified to estimate seismic permanent displacement in the presence of excess pore pressure buildup. The present study is original because the method not only simulates the generation of excess pore pressures but also considers the coupled procedure. In addition, centrifuge test results of lateral spreading in the infinite sloping ground are used to demonstrate that the proposed modification considerably improves prediction of seismic sliding displacement. The results clearly demonstrate that ignored pore-water pressure buildup in sliding block procedures can lead to unconservative estimates of seismic permanent displacements during seismic loading.