An Elasto-Plastic Model for Unsaturated Soils

The paper presents an elasto-plastic model describing the behaviour at yielding of partially saturated soils. This model assumes that the soil remains saturated until the air entry value is exceeded and its behaviour is controlled by effective stresses. Beyond this particular point, the soil becomes unsaturated and the model then makes use of two independent stress variables: "modified net stress" σ^* = σ – u_a + χ^* (u_a – u_w) and matric suction. An experimental programme was performed in suction-controlled apparatus on reconstituted clay from Ste-Rosalie, Canada. The agreement between observed and computed results is satisfactory and confirms the possibilities for the model to reproduce the most important features of partially saturated soil behaviour.