Experimental study on the mechanical properties of soil-structure interface under frozen conditions using an improved roughness algorithm

During soil freezing, the frozen strength of the soil-structure interface measured as shear strength is critical to the evaluation of the anti-heave performance of the structure. Hence, this paper presents an experimental study of the shear stress response, shear strength and shear strength indexes of a soil-structure interface under frozen conditions by utilising an improved roughness algorithm. This study also deeply analysed the effect of roughness, temperature, moisture content, and vertical stress on the evolution of mechanical properties. The results show that the shear stress-displacement characteristics of the soil-structure interface displays strain-hardening at room temperature and strain-softening at negative temperatures. The strain-softening characteristic, in particular, is more pronounced with a decrease in negative temperature. The shear strength, cohesive force, and inner friction angle present a trend of linear growth with an increase in roughness under different values of vertical stress, temperature, and moisture content. Under the same values of vertical stress and roughness, the reduction in temperature and increase in moisture content significantly improve the shear strength of the soil-structure interface. Compared with its composition of interface friction at room temperature, the shear strength in this case is mainly derived from the contribution of cohesive force under frozen conditions, i.e., the cementation of ice crystals.