Thermo-poromechanics-based viscoplastic damage constitutive model for saturated frozen soil

This study is primarily intended to present a viscoplastic damage theory for saturated frozen soil based on thermo-poromechanics. On the basis of the irreversible process of thermodynamics, an elasto-viscoplastic damage constitutive theoretical framework for saturated frozen soils is formulated by use of the Lagrangian saturation and solid-fluid interface interactions, for which the upscaling microscopic properties of saturated frozen soil in plasticity are provided to elucidate the macro stress-strain relation. Furthermore, a corresponding constitutive model for simulating the cryogenic triaxial stress state of saturated frozen soils is presented to take the influence of creep and loading strain rate into account. Compared with the cryogenic triaxial tests on saturated frozen soils, it is demonstrated that the time-dependent model proposed here can simulate the salient properties of frozen soils under constant shear stress and loading strain rate conditions. The constitutive theory proposed here provides a potential basis for analyzing the stress deformation considering the effects of creep and loading strain rate for saturated frozen soils in cold regions.