Investigating the Shear Behavior of Interfaces between Frozen Clay and Cement Blocks

The interfacial frictional resistance of anchor solids, bolt, and the surrounding soil of soil nails in the flexible support structures of frozen soil slopes is a key parameter for calculating and evaluating its stability. Based on a series of direct shear tests under the condition of a constant normal load boundary, the shear mechanical behavior of the interface between the soil and a cement slurry block under different soil temperatures, water contents, and normal pressures was studied, and the interfacial deformation mechanism was analyzed. The results show that in the thawing state, with the increase of water content, the shear surface moves from the side close to the soil to the side close to the cement slurry block. However, the shear plane is determined in the direct shear test, which makes the effect of the change of the soil's own strength on the interfacial shear strength smaller. In the frozen state, the behavior of the interfacial shear stress-shear displacement behavior at the same water content varies from strain-hardening type to strain-softening type with the temperature decreasing. The normal displacement is affected by temperature, normal pressure, and water content. At the same temperature, the maximum normal displacement gradually decreases with the increase of water content and normal pressure. At the same normal pressure and water content, the maximum normal displacement tends to increase and then decrease as the temperature drops. Still, the maximum normal displacement in the frozen state is more significant than in the thawing state. At the same water content and normal pressure, the interfacial peak shear strength shows a nonlinear increase with the decrease in temperature. At the same normal pressure and temperature, the interfacial peak shear strength delivers a linear increasing law with increasing water content. The peak interfacial cohesion increases with the decreasing temperature and increasing water content, and this phenomenon is more evident at lower temperatures. The interfacial friction angle does not change significantly with the rise in water content at the same temperature, but as temperature decreases, its average value increases significantly. The research results can provide a reference for the design of slope support structures in cold regions.