Energy‐Based Modeling of Stress–Dilatancy in Unsaturated Soils

ABSTRACT Several laboratory testing efforts have demonstrated the significant impact of suction on the dilatancy and peak shear strength of unsaturated soils. However, there are gaps in the literature regarding analytical models that accurately describe the stress–dilatancy behavior of unsaturated soils. This paper aims to fill this gap by incorporating suction into a thermodynamic model that describes the energy exchange between external stresses and soil. The derivation employs the enthalpy potential to establish the relationship between plastic strains, stress ratios, and friction. We consider the difference between net and effective stresses to derive the equations of dissipative and internal energies in unsaturated soils. The proposed model accounts for the stored energy associated with volume change, a consideration often overlooked in other models. Additionally, it integrates friction, which dissipates deviatoric energy at each stress level, and accounts for energy dissipation resulting from water flow. The accuracy of the proposed model is validated by comparing the predicted values against the measured stress–dilatancy data of five different unsaturated soils available in the literature. The findings demonstrate the capability of the proposed model to predict the complex stress–dilatancy response of various unsaturated soils with high accuracy, with errors significantly lower than those of the three alternative models. Furthermore, the proposed model successfully captures the suction‐hardening phenomenon.