Probabilistic Risk Assessment of Soil Slope Stability Subjected to Water Drawdown by Finite Element Limit Analysis

Abstract

This study investigates the probabilistic stability of embankment slopes subjected to water level drawdown using the random field finite element method (RFEM) with strength reduction technology. The shear strength of soil properties was controlled by cohesion and internal friction angle for the slope shear failure. The cohesion and internal friction angle were modeled by a random field following the log-normal distribution. The factor of safety (FOS) for the embankment slope with random soil is calculated by strength reduction technology. During the numerical simulation, the limit analysis upper bound and lower bound method are applied to the finite element method, respectively, to obtain the upper bound and lower bound value of the FOS. Seepage action is also considered during the water drawdown by setting five different water levels (WLs). A total of 1000 Monte Carlo simulations are performed for each work condition, resulting in histograms of the FOSs. The results show that the FOSs obtained by the random field model are all lower than those by the deterministic method. Even if the FOSs obtained by the two methods are close, there still exists the possibility of slope failure. Compared to the deterministic results, the RFEM method is more reasonable for evaluating slope stability.