Experimental investigation on the dynamic shear behavior of the unsaturated soil-concrete interface under cyclic loading

This study focuses on investigating the shear behavior of the Shanghai clay-concrete interface under cyclic loading using a large-scale multifunctional shear apparatus. Considering that soil-structure interfaces are typically found in shallow soil layers or even above the ground surface, the interface zone is unsaturated in its natural state, the shear experiments were therefore conducted on the tested soil with different water contents. The corresponding matric suction of the tested soil under different water content and initial dry densities was determined by the filter paper method. The experimental findings indicate a substantial influence of matric suction on the interfacial strength, revealing a pronounced non-linear relationship. The interface exhibits the highest shear strength during the initial shear, which gradually decreases with an increasing number of shear cycles. This reduction can be attributed to the weakening of the bonding effect at the interface caused by cyclic shear. On the other hand, the matric suction decreases with water content increases, leading to a decrease in interface shear strength. Additionally, the vertical cumulative displacement of the soil increases with higher water content.