An effective stress elastic–plastic model for unsaturated porous media

Abstract Within a three-phase framework, an extension of elastic–plastic models of saturated soils to unsaturated states has been presented in [Int. J. Numer. Anal. Meth. Geomech. 24 (2000) 893–927]. Here, the main concern is on the behaviour of the solid skeleton. A simple, yet effective, model for the elastic–plastic behaviour of unsaturated soils is described, requiring minimal number of material parameters to define the effect of desaturation. These material parameters are identified and the application of the model is demonstrated using a comprehensive set of data reported by Wheeler and Sivakumar [Geotechnique 45 (1) (1995) 35–53], that includes first wetting, followed by consolidation and finally triaxial compression tests. The model is also applied to describe qualitatively two characteristic features observed in experiments, e.g., plastic volumetric contractancy followed by an elastic response observed in normally consolidated soils subject to increasing values of suction, and elastic rebound upon wetting, unless compression is applied in which case collapse may occur.