The complicated heterogeneity and discontinuity of soil-rock mixture (SRM) usually cause high variability in SRM's creep characteristics, which can easily cause geological disasters (e.g., landslides) under harsh environment such as freeze-thaw (F-T) cycles. However, the nonlinear creep behaviors of SRM material, under varying internal structures induced by F-T cycles, skeleton changes and stress states, have not been reported and it is still challenging to describe these complicated creep behaviors using current existing creep models. Therefore, direct shear creep tests were carried out to study the creep evolutions of SRM under various F-T cycles (0 to 15 cycles) and rock contents (15% to 55%). A new element combination creep model was then proposed to describe SRM's nonlinear creep behaviors involving the instantaneous elastoplastic and viscoelastic-plastic deformations. Results showed that the creep deformation tended to decrease as the rock content increased. The initial 3 to 5 F-T cycles significantly affected the creep behaviour of SRM. The proposed new creep model could well describe the nonlinear creep behaviors of SRM material under different stress states.

The creep properties of soil-rock mixture (SRM) usually exhibit high variations after suffering harsh field conditions in cold regions such as freeze-thaw cycles, which can easily trigger landslides and threat the long-term stability of SRM slopes. However, the creep properties of SRM induced by freeze-thaw cycles have not been studied, especially in terms of the evolution of creep deformation and failure types under multiphase transitions within SRM material. Therefore, the shear and creep properties of SRM specimens under different freeze-thaw cycles (0 to 15 cycles) and rock contents (15% to 55%) were investigated to reveal the creep failure mechanisms of SRM using large-scale direct shear and direct shear creep tests. The shear stress-displacement curves, shear strengths, the creep curves and long-term strengths of SRM specimens were analyzed. Results showed that increasing freeze-thaw cycles tended to decrease the shear strength of the SRM specimen. The final creep deformation of SRM generally decreased with increasing rock content, and the first 3 to 5 freeze-thaw cycles resulted in significant creep displacement and the decrease of long-term strength.