Etude des mecanismes de fissuration dans les argiles saturees

This research consists of studying the fissuring mechanism in saturated clay.;For this purpose, Polytechnique Hollow Cylinder Fracture Tests (PHCFT) on saturated clay with an initial straight symmetrical slot and without the use of membrane have been made.;A significant difference exists between results of tests where the interfacial tension is zero (the fluid used is water) and those where the interfacial tension is different from zero. On the other hand the initial pore pressure (before the test) varied linearly as a function of the interfacial tension. The shear tests on samples soaked in different fluids without using a membrane and on samples with membrane confirmed these results.;In tests where water is used as fluid, the only resistance comes from the skeleton however the tests where fluids are such that the interfacial tension is different from zero represent the behavior of the skeleton + water. The difference between results obtained from tests with fluids and those with water represents the contribution of the pore water to the resistance.;The analysis of the results has been made by calculating the stress intensity factors and fissuring energy. (1) The calculation of the critical stress intensity factors showed that the rupture takes place when that due to the skeleton and also that due to the skeleton + water reaches a critical value. (2) The calculation of the fissuring energy indicates a linear relationship with the length of the fissure for the skeleton as well as for the skeleton + water. The fissuring energy is independent of the initial fissure length.;As a conclusion, the tensile failure criterion of rupture is not governed by the effective stresses neither by the total stresses but by a mixed stresses (f (sigma, u) or f (sigma', u)) because failure takes place when the two components of saturated clay get the rupture. (Abstract shortened by UMI.).