Effects of Cross Anisotropy on Three-Dimensional Behavior of Sand. I: Stress–Strain Behavior and Shear Banding

The significance of material cross anisotropy in sands is underscored and experimentally evaluated in a series of true triaxial tests on Santa Monica beach sand in a cubical device. Failure patterns, initiation and development of shear banding, and complete stress–strain behavior are described for the entire range of the Lode angle under general three-dimensional loading conditions. Localized failure was found to govern the ultimate resistance of the sand for intermediate values of parameter b=(σ2-σ3)/(σ1-σ3) in each of the three sectors of the octahedral plane. Variations of the friction angle are fully described and show its significant dependence on the inherent cross-anisotropic material structure.