CONSTITUTIVE BEHAVIOR OF STRESS-INDUCED ANISOTROPIC COHESIVE SOIL

This paper describes the stress-strain response of a cohesive soil subjected to stress-induced anisotropy. A directional shear cell (DSC) is utilized in the experiments. The DSC is capable of applying independently controlled normal and shear stresses on four vertical faces of the cubical specimen under plane strain conditions, thereby controlling the magnitude and orientation of the principal stresses that are applied to the specimen. In the experiments reported herein, the fabric anisotropy in the soil is induced by preloading. The initial loading direction coincides with the material principal axes, and the directions of the reloading principal stresses are applied in discrete jumps at specified orientations relative to the direction of the initial loading. When the specimen, are reloaded at the various orientations of the principal stress directions, the results reveal the pronounced effects of the stress-induced fabric anisotropy, as indicated by significant variations in the stress-strain responses. The stiffness moduli significantly decrease and the maximum strain and the volumetric strain increase with the increasing rotation angle of the stress direction.