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.