Reliability Analyses of Slopes Incorporating Head and Flow Anisotropy as Random Variables

Probabilistic risk analyses can provide a quantitative measure of error propagation in the analysis of slope stability and help determine the probability of slope failure. This study proposes two closed-form solutions that estimate the pore fluid load for the Culmann failure mode. The First Order Second Moment and Hasofer-Lind methods make it possible to compute the contribution of the uncertainty in each individual parameter to the overall uncertainty in the slope stability, enabling an assessment of the influence of pore pressure and anisotropic permeability on the probability of failure. Evaluations include an initial comparison of the closed-form solutions with a simple finite element model for flow through porous media, followed by a parametric analysis implementing the closed-form equations. The proposed closed-form solutions for flow effects are comparable to the finite element solutions and thus have the potential to be valuable tools in reliability analyses, provided that the scope of applicability is well understood.