A micro-mechanical model for unsaturated soils based on DEM

A micro-mechanical model to study the microscopic and macroscopic behavior of unsaturated soils under different suctions is proposed in this study. In the model, a novel pore-scale numerical method for simulating the liquid–solid interfaces is proposed first. A discretization of the particle surface using Fibonacci-Lattice is then introduced to calculate the capillary forces from the complex liquid–solid interfaces. The joint influence of capillary forces and the interparticle contact forces on the motion of the particles are handled by the discrete element method (DEM). The effective stress parameter estimated by the model is compared with the experimental results for unsaturated soils, which confirms the validity of the proposed micro-mechanical model. The microscopic responses (liquid–solid interfaces, capillary forces, contact forces and coordination numbers) and macroscopic responses (strength, stress–strain relationship and volume change) of unsaturated soils in desaturation tests and triaxial tests are studied by the proposed model.