Elastoplastic constitutive model for frozen sands based on framework of homogenization theory

In this paper, the stress–strain responses of frozen sands and an elastoplastic constitutive model based on the homogenization theory of heterogeneous materials are presented. In the model, frozen soils are conceptualized as binary-medium materials consisting of bonded blocks and weak bands, and their mechanical behavior is described with elastic–brittle and elastoplastic constitutive models, respectively. By introducing two groups of parameters (i.e., the breakage ratio (λv and λs) and strain concentration coefficient (cv and cs) related to the spherical and deviatoric stress components), the proposed model incorporates the breakage process of ice crystals and nonuniform strain distributions between the matrix (bonded elements) and inclusions (frictional elements) of the heterogeneous frozen soil samples. Moreover, an elasticity-based model and a double hardening constitutive model are employed to simulate the mechanical properties of the bonded elements and the characteristics of the frictional elements, respectively. To provide appropriate and quantitative predictions with the binary-medium constitutive model proposed here, triaxial compression tests are performed on the frozen and unfrozen sands to determine the individual parameters at confining pressures of 300–1800 kPa. The model validations demonstrate that the predictions agree well with the available laboratory results.