4 CONCLUSIONS

Through a controlled-temperature direct shear test system, this paper systematically investigates the shear characteristics of the interface between frozen soil and concrete under constant normal stiffness conditions, and arrives at the following conclusions: (1) With the increase in temperature and water content, the interfacial curve gradually transitions from a strongly hardening type to a weakly hardening type. The initial shear stiffness of the interfacial shear stress-shear displacement curve gradually increases, and the interfacial shear strength also gradually increases. (2) In the thawed state, there is no significant change in the curve morphology as the normal stiffness increases, all exhibiting strong strain hardening with a relatively small elastic deformation stage. In the frozen state, as the normal stiffness increases, the curve morphology transitions from a strongly hardening type to a weakly hardening type. The initial elastic stage of shearing is more pronounced, corresponding to a larger displacement. In the residual stage, the increment of shear stress decreases as the shear displacement increases. (3) Under normal temperature conditions, the peak interfacial shear strength gradually increases with the increase in normal stiffness, and this trend becomes more pronounced as the normal stress increases. Under negative temperature conditions, the peak shear strength significantly increases with the increase in normal stiffness, and this trend becomes more evident as the temperature decreases. Correspondingly, the interfacial cohesion and friction angle also increase with the increase in normal stiffness.