Deformation,strength,yield and moisture change of a remolded unsaturated loess

This paper studies the deformation, strength,yield and moisture change of a remolded unsaturated loess. Three types of stress path tests using a modified triaxial apparatus were conducted, i.e., an isotropic compression test with controlled suction, a triaxial shrinkage test with controlled net mean stress and a triaxial drained shear test with controlled suction and net cell pressure. The results show that stress paths have significant effect on the deformation and moisture change of unsaturated soil, the soil water charateristics curve is dependent on net mean stress,the shear strength versus suction relationship is non linear,the parameter for water content change under triaxial shear condition is approximately a constant, the net mean yield stress and deviatoric yield stress increase with suction, and the yield suction is not necessary equal to the maximum suction experienced by the soil specimen under constant net mean stress. Based on the test data, a modified yield criterion associated with suction increase is proposed. In addition, a new method to identify the yield stress under triaxial shear condition is suggested.