Constitutive model for cyclic behaviour of interfaces with variable dilatancy

In the context of numerical approaches such as the finite element method very often body and interface elements whose constitutive models are developed separately are used. However, for a given mass of soil, a relationship between these two constitutive models could be obtained, providing a more satisfactory approach. Actually experimental results show some common features in the behaviour of body and interfaces in geomaterials. The dependancy of the dilatancy to the mean effective pressure is a good example. The purpose of our study is to propose a cyclic interface constitutive model derived on the basis of an elastoplastic body constitutive law. Usually, stick, slip, debonding and rebonding of the interface happen during subsequent loadings and unloadings. Cyclic loading functions with a memory of the last loading reversal are used to model these features. Finally the model is entirely developed with respect to effective stress vectors and is thus especially suited for the analysis of the influence of the pore pressure.