An explicit-implicit THM-Coupled MPM for saturated porous media

The thermal-hydro-mechanical (THM) responses of porous media underpin the operation and performance of key engineering applications. In this study, we introduce a coupled material point method (MPM) to model the THM behaviour of saturated soils. The governing equations are presented using the u-v-p-T formulation adaptable for dynamic and large deformation problems. An effective explicit-implicit solution scheme is further developed wherein the pressure is solved using the operator-splitting method to avoid the constraint of liquid compressibility. The proposed method is validated by simulation of a three-dimensional axisymmetric benchmark scenario involving the thermoelastic response around a point heat source. We further demonstrate the proposed method by simulating the large deformation and progressive failure in a slope caused by thermal softening. The results indicate that the presented method has the potential to simulate climate-change-driven soil degradation and related problems, such as thawing permafrost.