Experimental Study on the Shearing Behaviour on the Interface between Coarse Sand and Concrete under High Stress

The shear behaviour on the interface between soil and structure is a research hot point. Based on the RMT-150B rock mechanics test system, a series of high-stress direct tests were performed on the coarse sand under the condition of different moisture contents and concrete substrates with different rough and hardness. The results showed that the shear stress-displacement curve and volumetric strain-displacement curve of the interface under high stress could be fitted by a hyperbolic model; the ultimate shear strength and initial shear stiffness of the interface both increased with the normal stress while the shear stiffness decreased with the shear displacement. The crushing rate of the coarse sand particles on the interface increased with the normal stress. After the range analysis for the influencing factors of the interface’s shearing behaviour, it was shown that for the ultimate shear strength, their sequence of influencing degree was normal stress, the roughness of interface, moisture content, and hardness of concrete base; for the initial shear strength, the sequence was normal stress, moisture content, interface roughness, and basal hardness. As for dry sand, the possibility of relative particle crushing was higher than that of sand with a moisture content of 8%, and a peak of crushing occurred when the moisture content was 16%.