Abstract: The strength characteristics of the interface between saturated clay and structure were analyzed by triaxial instrument. Shear strength and excess pore water pressure at the interface between saturated clay and structure were measured by prefabricating an inclined and drilled structure surface, forming a triaxial composite sample with saturated clay. Compared to the interface direct shearing test which can not distinguish the shearing rates effect and drainage effect of the interface strength characteristics, the proposed method can accurately control the drainage conditions and clarify the influence of the shearing rates on the interface strength. Triaxial consolidated undrained interface shear tests with various surface roughness and shearing rates were carried out. Direct interface shear tests under various shearing rates were also conducted. Results show that the shear strength and excess pore water pressure increase with the increase of the roughness of the structural surface under the same confining pressure. The shear strength and the axial strain required for the stability of excess pore water pressure at the interface increase with the increase of shearing rates. Strict control of drainage conditions and accurate measurement of excess pore water pressure at the interface are of great significance for measuring the interface friction angle between saturated clay and structure.

Key words: interface strength, shearing rates, roughness, saturated clay, excess pore water pressure, stress ratio