A damage-softening and dilatancy prediction model of coarse-grained materials considering freeze–thaw effects

The variations in mechanical properties of coarse-grained materials (CGM) caused by freeze–thaw cycles must be considered when designing subgrades in seasonally frozen regions. In this study, consolidated-drained triaxial tests are performed to investigate the properties of CGM under different numbers of freeze–thaw cycles and effective confining pressures. Typical test results are presented and discussed. Strain softening and dilatancy are observed during shearing. Motivated by experimental observations, a stress–strain prediction model that can reflect the residual strength is proposed, using the framework of continuum damage mechanics. A dilatancy prediction equation is then developed by taking the deviatoric stress as the rate of energy consumption. The effect of freeze–thaw cycles on the mechanical behaviour of CGM is fully incorporated in the degradation of the elastic modulus, peak, and residual strengths in the current model. A comparison of the predicted and test results highlights the suitability of the proposed model for capturing the effect of freeze–thaw cycles on the mechanical properties of CGM. Overall, the investigation demonstrates the potential for using strain-softening and dilatancy models to predict geotechnical degradation characteristics of CGM in seasonally cold regions.