Mechanical behaviors and elastoplastic damage constitutive model for heterogeneous frozen soil

The significant feature that distinguishes frozen soil from unfrozen soil is the existence of ice structures within it. To investigate the effect of ice lenses on the mechanical properties of frozen soil. A series of tests were conducted on three types of heterogeneous frozen soil under different temperatures and normal stresses. The test results showed that the strength and ductility of frozen soil decrease as the number of ice lenses increase under the same temperature and normal stress. The ice lenses within frozen soil intensify its strength attenuation under loading, the damage variable considering the cutting effect of ice lenses were established based on the fracture mechanics, and an elastoplastic damage constitutive model for heterogeneous frozen soil was proposed. The method was redeveloped in COMSOL Multiphysics, and the rationality was verified based the test results. The variation of damage variable and plastic strains of heterogeneous frozen soil under shear loading were analyzed.​ Finally, a digital model of undisturbed frozen soil was established using X-ray CT, and the failure mechanisms of the undisturbed frozen soil were investigated by the proposed model.