Stochastic study of stability of unsaturated heterogeneous slopes destabilised by rainfall

Abstract

Failure of unsaturated soils due to rainfall infiltration is a threat in many parts of the world with temperate or hot climate. Understanding of unsaturated slope stability during rainfall infiltration is an important but complex problem. The shear strength of unsaturated soil depends on soil suction and positive pore water pressure which are governed by the water flow. In addition, the soil porosity can vary spatially quite significantly which generates atypical preferential paths for the water flow. This can lead to unusual suction reduction and/or build-up of positive pore pressure over the domain. This study nummerically investigates the stability of an unsaturated slope with spatially varying porosity. The random finite element method and the shear strength reduction technique are employed to probabilistically estimate the change in factor of safety during and after a rainfall event. Through Monte Carlo simulation, the study shows that the heterogeneity of porosity can alter the failure mechanism and the probability of failure of the unsaturated slope

Stochastic study of stability of unsaturated heterogeneous slopes destabilised by rainfall