A fully coupled flow deformation model for cyclic analysis of unsaturated soils including hydraulic and mechanical hystereses

A fully coupled constitutive model is presented for describing the flow and deformation behaviour of unsaturated soils. The elastic–plastic behaviour due to loading and unloading is captured using the bounding surface plasticity. The hydraulic hysteresis is accounted for through the soil water characteristic curve. The coupling between fluid flow and deformation fields is established using the effective stress parameters. Attention is also given to the interrelations between the effective stress and wetting and drying paths, and the shift in the soil water characteristic curve with the matrix deformation. A single set of material parameters is introduced for the characterization of the coupled constitutive model. Comparisons are made between the simulation results and experimental data from the literature highlighting capabilities of the model.