FEniCS simulation of a partially saturated slope under varying environmental loads

Paper in proceeding, 2023

This paper presents a numerical simulation of the response of a partially saturated slope under the impact of a long heavy rainfall event. The results are shown as a chart of varying safety factor over time. The powerful FEniCS finite element framework is employed to solve the governing coupled Hydro-Mechanical (HM) balance equations. An extended version of the Mohr-Coulomb failure criterion that accounts for partial saturation is implemented in Fortran and called from within FEniCSscript to carry out the stress integration and plastic correction. The safety calculations are performed using the strength reduction technique, firstly using Bishop’s effective stress, and secondly using two independent stress measures (i.e., net stress and suction). The impact of the chosen stress measures on the results is briefly discussed. The results highlight the importance of considering the unsaturated soil behaviour in the estimation of the safety margin, and to answer the important question of when and where the failure might occur.