Experimental investigations on the shear strength and creep properties of soil-rock mixture under freeze-thaw cycles

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.