Coupled hydro-mechanical model for partially saturated soils based on Cam-Clay plasticity

This paper presents a numerical model of coupled hydro-mechanical behaviour of partially saturated soils. The model is based on Bishop's effective stress concept and the Cam-Clay model, with the compression stiffness influenced by the effect of partial saturation. The mechanical model is accompanied by the simplified water transport model where the water pressure is the only variable and van Genuchten moisture retention curve was adopted. The governing equations are discretized in the framework of the finite element method, and the resulting model is implemented in the in-house open source software package SIFEL. To improve convergence of the Newton-Raphson method used at the global level of the equilibrium finding, the algorithmic stiffness matrix was derived for the used stress return algorithm. A numerical examples of foundation problem illustrates the effective application of the model and proved that the model can capture wetting collapse.