Elastoplastic Modelling of Hydro-mechanical Behaviour of Unsaturated Soils

The development of constitutive models for unsaturated soils is briefly reviewed, and the state-of-the-art of elastoplastic constitutive models for unsaturated soils is summarized. This paper introduces an elastoplastic model that couples hydraulic and mechanical behaviour for unsaturated non-expansive and expansive soils. The two coupled elastoplastic constitutive models are illustrated with laboratory tests to show their application and performance. Hydraulic hysteresis in the soil-water characteristic is modeled as an elastoplastic process with the elastic region of the degree of saturation. The effect of change in degree of saturation on the stress-strain-strength behaviour and the effect of change in void ratio on the soil-water characteristics are taken into consideration in the model in addition to the effect of suction on the hydraulic and mechanical behaviour.