Effects of interface models on deformation of interface between slab and cushion layer and slab stress of concrete faced rock fill dam

Three-dimensional static and dynamic elasto-plastic finite element analyses are conducted on a concrete faced rock fill dam. Three different soil-structure interface models are used to simulate the interface between slab and cushion layer, including hyperbolic model (only for static analysis), ideal elasto-plastic model and ageneralized plastic model. The slab stresses are nearly the same among three interface models after construction. The slope-direction slab stresses are also slightly different among three interface models during impoundment, while the axial-direction slab stresses have clear differences. The stress path and shear deformation between slab and cushion layer calculated by the generalized plastic model are different from those by the hyperbolic and ideal elasto-plastic models during impoundment. The slope-direction stress induced by the residual deformation is slightly different between the generalized plastic and ideal elasto-plastic interface models, but the axial-direction stress is much larger for the ideal elasto-plastic model. The ideal elasto-plastic model can only produce plastic deformation when the stress reaches the peak strength, and the shear deformation of interface during earthquakes will be underestimated. The generalized plastic interface model can reflect the dilative and contractive responses, strain hardening, softening, particle breakage and cyclic residual deformation, which is more close to reality.