An elastoplastic binary medium constitutive model for saturated frozen soils

The constitutive model for frozen soils is one of the hot research topics in the frozen soils mechanics. In this paper, the loading-unloading-reloading tests are carried out with different confining pressures to further investigate the deformation characteristics for frozen soils, and it is found that the elastic and plastic deformation of frozen soils do not occur simultaneously in the shear process, which demonstrates that this two types of deformations have different physical mechanisms. Then these two deformation mechanisms are studied under the framework of breakage mechanics for geomaterials by taking the ice-cementing part as the bonded elements (Elastic characteristic) and breakage part as the frictional elements (Plastic characteristic) in frozen soils. Based on the above results, the binary medium constitutive model for frozen soils is derived with the homogenization theory, considering this breakage mechanisms and the nonuniform distribution of stress. Meanwhile, a more reasonable methods for obtaining the evolution functions of breakage ratio and stress concentration tensor are presented. Finally, the parameters of this binary medium model are determined through experiments to duplicate the test curve of frozen soils, and the computed results demonstrate that the constitutive model proposed here can well simulate the deformation characteristics of frozen soils.