Abstract:Based on the review of some classic interface elements,a twin-body model is offered for research on mechanical performance of interface between rock and concrete for the assessment of stability of concrete dam foundation. In this paper,FLAC,a finite difference program,is utilized to model the mechanical behaviors of rock-concrete and rock-rock interface with the action of compressive and shear loads. The stress,displacements and plastic zone distribution are obtained to explain the model failure and the effect of interface. Results show that some different stages happen in the damage process and the interface roughness has an obvious effect on the mechanical behaviors of the model.