Modeling of Initial Stresses and Seepage for Large Deformation Finite-Element Simulation of Sensitive Clay Landslides

Abstract

Groundwater seepage and an increased lateral earth pressure coefficient at rest (K0) increase the potential for triggering large-scale landslides in sensitive clays. After the failure is triggered, the successive retrogressive failure of soil blocks in the undrained condition is influenced highly by K0. This paper presents the numerical techniques for modeling seepage and K0 using an Eulerian-based large deformation finite-element method. The finite-element simulation was performed first for a drained condition to calculate the in situ effective stresses and seepage forces, which then were used to model subsequent undrained retrogressive failure in total stress, triggered by toe erosion. A strain-softening- and strain-rate-dependent undrained soil strength model, which captures the behavior of soil failure from its intact condition to the fluidlike remolded material flow, was adopted in the retrogressive failure analysis. The simulation covered different phases of the landslide, including the initiation and retrogression of failure, and debris flow. Using the developed numerical technique, the 2010 Saint-Jude landslide in Quebec, Canada, was simulated.