The interface between structure and coarse grained soil was found to exhibit remarkable coupling of shear stress-strain relationship in both the directions due to three-dimensional shear application based on test results. The magnitude of principal shear strain is only dependent on the magnitude of principal shear stress. A three-dimensional constitutive model and its numerical scheme were then developed based on the elastoplasticity damage theory

which was programmed and used to predict the response of soil-structure interface. The model and its numerical scheme were confirmed to reasonably characterize main behaviors including the coupling of shear stress-strain relations of the interface between structure and coarse grained soil

which may have much effect on the response of interface.