Arezou Modaressi

A constitutive model for cyclic behaviour of interfaces with variable dilatancy

Abstract 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.

Modeling of stress distribution in granular piles: Comparison with centrifuge experiments

The classical method to compute stress and strain distributions in granular materials is recalled using continuum mechanics approach, and different rheological laws described. It is recalled that granular materials exhibit highly nonlinear response such as nonlinear elasticity, dilatancy and plastic flow. Finite element technique is used to predict the stress field distribution below a conic and a triangular pile. The dependence of the stress distribution on the rheological law, the bottom boundary condition and the building process (horizontal or inclined strata) is demonstrated. These results are compared to experimental data obtained in centrifuge. (c) 1999 American Institute of Physics.