An elastoplastic damage constitutive model for frozen soil based on the super/subloading yield surfaces

Soil particles and ice form bonded structure in frozen soil. The modulus and bond strength of frozen soil decrease with the damage of the bonded structure during deformation. An elastoplastic damage constitutive model, based on the super/subloading yield surfaces, is proposed for frozen soil, in which the damage variable and bond strength are used to consider the elastic and plastic damage respectively. The model is validated with the observed mechanical behaviors of frozen sandy soil and frozen saline soil in triaxial compression tests with different confining pressures. The comparisons illustrate that the model can describe the hardening/softening and dilatancy of frozen soils with the change of confining pressures. The results also show that the expansion of frozen soil during shear is related to the loss of bond strength induced by the development of damage of the bonded structure.