Anisotropic constitutive model of frozen silty clay capturing ice cementation degradation under high mean stresses

Research results show that comparing to unfrozen soil, frozen soil has more complicated deformation behavior owing to the presence of ice. On the basis of triaxial tests results of frozen silty clay (FSC) at ˗6 °C, due to the ice cementation, the critical state line (CSL) of FSC does not cross the origin of the deviatoric plane. The critical deviatoric stress of FSC increases nonlinearly as the mean stress growing; however, further increases of the mean stress give rise to the decreases in the critical deviatoric stress. Because under high mean stresses, the ice-melting and-crushing (IMAC) cause ice cementation degradation. To predict the deformation of FSC, a new anisotropic constitutive model that considers the degradation of ice cementation is proposed. In the proposed model, first, the elastic parameters of FSC are obtained by conducting triaxial shear loading-unloading (TSLU) tests and isotropic compression loading-unloading (ICLU) tests. Second, yield and plastic potential functions are proposed, the two involve the modified mean stress and indicate the degradation of ice cementation. Third, a double hardening law pertaining to isotropic hardening and rotational hardening is developed by considering initial anisotropy and stress-induced particle rotation under shear loading. Finally, the comparison results confirm that the developed constitutive model is valid and suitable for describing the stress–strain relations of FSC.