Three-dimensional Analysis of Rainfall-induced Slope Failure

Abstract

Numerical simulations and flume experiments were performed to investigate the mechanism of slope failure due to rainfall events. A three-dimensional (3D) seepage flow numerical simulation model was coupled with a two-dimensional (2D) surface flow and erosion/deposition model for the seepage analysis. The conventional water-phase (one-phase) seepage-flow model assumed only water-phase flow in the seepage analysis, which was inadequate for unsaturated soil domains. A water-air two-phase seepage-flow model that considered both the water and air phases in the seepage-flow process was also used for the seepage analysis. The pore-water pressure and moisture-content data obtained from the seepage-flow model were used to analyze the slope stability. Janbu’s simplified method and the extended Spencer method were used for the stability analysis. The numerical simulation and experimental measurements agreed satisfactorily in terms of moisture and air movement, seepage outflow rate, surface water forefront propagation, predicted critical slip surfaces, and time of failure of the considered slope.