Yielding and critical state of a collapsible unsaturated silty soil

Isotropic and anisotropic compression tests, and drained triaxial shear tests were performed on a collapsible unsaturated silty soil under various suctions. The results show that the concepts of yielding and critical state originally developed for saturated clays can be applied to this unsaturated material when the matrix suction is considered as an independent variable. Pre-yield and post-yield behaviour is clearly defined, the yield curve increases in size with suction, and the effect of suction on the critical state strength decreases with increasing net mean stress. Des essais de compression isotrope et anisotrope et des essais triaxiaux de cisaillement draine ont ete realises, pour differentes valeurs de succion, sur des cols silteux non satures effondrables. II apparait que les concepts d'etat limite et d'etat critique, initialement developpes pour les argiles saturees, sont applicables a ce type de materiau non sature si la succion matricielle est consideree comme variable independante. Les comport...