More and more attention was paid to the behavior of bedrock-dam materials interface in earth rockfill dams. The hyperbolic hardening rule for constitutive model of coarse grained soil is introduced into the model for soil-structure interface and thus a simple elasto-plastic interface model is suggested. The expression of stiffness matrix of interface model is derived. The performance of proposed model is demonstrated by comparing its predictions with direct shear test results for different types of granular soils

including sand and rockfill materials

during shearing. Within the framework of thin layer element finite element scheme

the interface model is applied in numerical finite element program. Combining Rumei high core-wall dam example

shear sliding property of shear band between dam materials and valley is analyzed. Simulation results show that tangential displacements of middle zone of slope is relatively large while the edge zone is relatively small. These are in accordance with the sliding law of coarse-grained soils

which provide a favorable reference to research on shear sliding property of bedrock-dam materials interface and deformations calculation of earth-rock dam.