Multi-phase Modelling of Unsaturated Soils

A computational model is developed for a fully coupled analysis of " ow and deformation problems in variably saturated soils. The hydro-mechanical model is formulated with in a three phase framework using mass and momentum balance equations and the effective stress approach. The stress-strain behaviour is described through the bounding surface plasticity theory. Numerical implementation of the coupled " ow-deformation equations together with the elastic-plastic constitutive model is demonstrated through the finite element approach. The governing equations are discretized spatially using the standard Galerkin method while the finite difference technique is employed for the discretisation of the time domain. The elastic-plastic constitutive equations are integrated using an explicit integration algorithm along with a stress correction scheme. Performance of the model is investigated by comparing numerical predictions with experimental data for unsaturated soils.