An elastoplastic constitutive model for frozen soil considering fracture of cryostructure and propagation of cracks

The natural frozen soil is formed in long-term geological processes under complex climatic conditions, and the special cryogenic structures are engendered in it. Investigation on the mechanical model of frozen soil with cryostructure can provide reliable measures to control and dispose the deformation of engineering foundations in cold regions. In this research, the crack initiation criterion and propagation path of frozen soil containing ice lens were studied based on available laboratory results. For the frozen soil containing ice lenses, the failure was formed by the propagation and penetration of the wing cracks at tip of ice lens. According to the fracture mechanics and strain energy theory, the structural damage variable of frozen soil was established, the effects of ice lens geometric parameters on the damage variable were analyzed. The elastoplastic tensor of frozen soil with cryostructure was modified using the damage variable which considering fracture of cryostructure and propagation of cracks, and an elastoplastic model was established. The PDE module in COMSOL was adopted to redevelop the proposed model, the rationality of the model was verified and the mechanical properties of natural frozen soil was investigated.