FORMULATION OF THE STRENGTH CRITERION FOR A POROUS-MEDIUM

The relationship between the macroscopic strength criterion of a fluid -saturated porous medium, modelled as a periodic heterogeneous medium, and the microscopic strength properties of the solid material, is inv estigated within the framework of the yield design homogenization meth od. If the solid material is purely cohesive or if the skeleton is for med by the assemblage of infinitely resistent grains with pointwise co ntacts, the criterion of the porous medium may be expressed by means o f a condition involving the tensor of ''effective stress '' only, thus giving legitimacy to the classical Terzaghi postulate. Moreover, a co unterexample of materials for which this postulate is not valid is exh ibited