Analysis of the Sand-Concrete Interface Shear Behaviors Considering the Soil Unloading and Interface Roughness Effects

The interface shear behaviors between sand soil and concrete were analyzed considering the soil unloading and interface roughness effects by the direct shear tests. The analysis results show that the soil unloading has a negative effect on the difference in ultimate shear stress between the adjacent roughness. Regardless of the value of consolidation normal stress, the soil unloading effect can cause the ultimate shear stress decreased and the higher value of roughness corresponding to a higher decrease rate of it. The values of roughness and soil unloading degrees also have a negative effect on the residual ratio of interface shear strength f_r. The influence of roughness on the interface shear dilation can be suppressed with the increased of the applied normal stress and make the interface transform gradually into the shear shrinkage state. A new test evaluation method of the interface shear influence range is proposed and compared with the theoretical analysis results. The analysis results may provide a new research approach for revealing the shear mechanism of the sand-concrete interface.