Constitutive model for sand-structure interface under constant stress increment ratio stress paths

Based on the simple shear test results of sand-concrete interface under the CSIRSP (Constant Stress Increment Ratio Stress Paths), a bi-potential surface elasto-plastic model for soilstructure interface is proposed on purpose for describing the interface deformation behavior, including strain softening and normal dilatancy, as well as the effect of stress paths. The model is formulated in the framework of generalized potential theory, in which the soilstructure interface problem is regard as a two-dimensional mathematical question in stress field, and plastic state equations are used to replace the traditional field surface. In the model, the relation curves of stress ratio and tangential strain are fitted by a piecewise function composed by hyperbolic function and hyperbolic secant function. The normal strain can be divided into two parts, one is normal compression strain, and another is normal dilatancy. The relation curves of normal dilatancy and tangential strain are fitted by another piecewise function composed by quadratic function and hyperbolic secant function. Finally, the predictions of the model have been compared with experimental results, and results show the model is reasonable and practical. © 2012 ejge.