EXPERIMENTAL STUDY ON CHARACTERISTICS OF DEFORMATIONAND STRENGTH OF UNSATURATED CLAY

A series of triaxial tests were carried out using double-cell triaxial system for unsaturated soils to investigate the behavior of volume change,yield and strength of unsaturated clays.The stress paths included drying with isotropic stress,isotropic compression and shearing with controlled suction.The results show that the clay exhibited an elasto-plastic shrinkage upon drying with low suction,indicating the existence of the suction-increase(SI) yield locus.During isotropic compression,the yield stress increases with increase of suction and the loading collapse(LC) yield curve changes parabolically.Increasement of net normal stress has more significant effect on the behavior of volumetric change than that of matric suction.The stress-strain relationship depends on the combinational style of net normal stress and matric suction,and suction enhances the stress-strain stiffness feature during triaxial shear test.Under conditions of different values of constant suctions,the effective friction angle is approximate a constant,and cohesion coefficient versus suction relationship is approximately linear.