A coupled hydro-mechanical peridynamic model for unsaturated seepage and crack propagation in unsaturated expansive soils due to moisture change

This paper presents a coupled hydro-mechanical peridynamic (PD) model to simulate unsaturated seepage and crack propagation due to moisture change in unsaturated expansive soils. The PD form of the nonlinear moisture diffusion equation is derived by using the PD differential operator (PDDO). The bond-based PD equilibrium equation includes the effect of elastic strain due to moisture change. These coupled field equations are solved by employing explicit schemes. Their accuracy is established by simulating the transient flow in the unsaturated soil pillar, steady flow in the unsaturated soil dam, and crack propagation in the cylinder soil specimens. The PD fluid pressure predictions are in good agreement with the analytical and numerical results. The crack propagation process and crack patterns are similar to the experimental observation. The results show that coupled hydro-mechanical PD model can capture realistic hydraulic and mechanical behaviors of unsaturated expansive soils.