A hydro-mechanical constitutive model for unsaturated soils considering hydraulic hysteresis based on coupled elasto-plastic formulation

Successful prediction of unsaturated soil behavior is a complicated task as the simultaneous effect of net stress and matric suction on degree of saturation and void ratio needs to be considered. Although, numerous constitutive models are developed to capture the hydro-mechanical behavior, these models either lack sufficient accuracy in simulating the fundamental behavior of unsaturated soils or rely on a formulation that is too complex to yield accurate results. Therefore, there still need coherent theoretical models backed by efficient algorithms for understanding the hydro-mechanics of unsaturated soils. This study introduces such a sound hydro-mechanical model based upon elasto-plasticity including hydraulic hysteresis. The proposed model relies on a relatively straight forward yet powerful formulation compared to similar models of its kind. The model needs material parameters that require only a handful of triaxial tests to obtain. Particular attention is given to the effect of change in void ratio on the water retention behavior. An efficient explicit scheme is utilized in integrating the model, where a number of unsaturated triaxial tests at constant suction and constant water content are simulated under various net stress and suction paths. Verification analyses result in good accuracy showing the capability of the proposed model for unsaturated soils. © 2024 Gazi Universitesi. All rights reserved.