Hydro-mechanically coupled elasto-plastic model for unsaturated soils including hydraulic hysteresis

This study introduces a hydro-mechanically coupled elasto-plastic model for unsaturated soils, including hydraulic hysteresis. The model focuses on the isotropic compression behaviour, requiring only three additional model parameters for the hydraulic part, which are determined with a single unsaturated triaxial test. This makes the proposed model significantly more practical while maintaining the desired level of accuracy. The formulation is developed, including the coupling terms that relate the change in water content to net stress and, in turn, the change in void ratio to water retention behaviour. An explicit scheme is utilized in integrating the formulation, where several unsaturated triaxial tests are simulated under various net stress and suction paths. Verification analyses show that the proposed model can capture the coupled response of unsaturated soils more effectively and consistently.