YIELDING AND CRITICAL-STATE OF A COLLAPSIBLE UNSATURATED SILTY SOIL

Isotropic and anisotropic compression tests, and drained triaxial shea r tests were performed on a collapsible unsaturated silty soil under v arious suctions. The results show that the concepts of yielding and cr itical state originally developed for saturated clays can be applied t o this unsaturated material when the matrix suction is considered as a n independent variable. Pre-yield and post-yield behaviour is clearly defined, the yield curve increases in size with suction, and the effec t of suction on the critical state strength decreases with increasing net mean stress.