Abstract:The mechanical properties of the soil-structure interface are of great significance for the study of the interaction system between soil and structure. The properties of surrounding soils and the surface roughness of the structure are important factors affecting the mechanical properties of the contact surface. To investigate the influence of surface roughness of concrete structure on shear behavior of soil-structure interface, a series of large scale direct shear tests were performed for interfaces between different soil types (red clay, sand and gravelly soil) and concrete. The surface roughness was changed by prefabricating different numbers of regular semicircular grooves on the concrete surface, and the surface roughness of the concrete was quantitatively evaluated by sand filling method. Based on the results of tests, the influence of surface roughness on shear stress-shear displacement curves and shear strength parameters of different types of interface were discussed. The test results indicated that three types of shear stress versus shear displacement curves were observed for interface between different soils and concrete, including strain softening for red clay-concrete interface, perfect plasticity for sand-concrete interface and strain hardening for gravelly soil-concrete interface. The shear strength of different types of interface increased obviously with increasing roughness. But the benefit of surface roughness was weakened under a higher normal stress. A clear linear relationship between interfacial shear strength and normal stress was observed under different roughness conditions, indicated that the shear failure of interface agreed well with the Mohr-Coulomb strength criterion. The increasing roughness could remarkably increase the apparent cohesion of interface, but had little influence on internal friction angle of interface.