Homogeneous and layered sand in triaxial compression

Samples of Ham River sand were prepared at high and low porosities by pouring through air or a liquid, the techniques being alternated for layered samples. Some samples were reinforced with horizontal sheets of various materials. To avoid edge effects near lubricated platens in triaxial compression, strains in the middle third of each sample were recorded in accurate detail. Changing the relation of the plane of deposition to the major principal stress direction revealed inherent anisotropy effects. Stress-strain and strength data show the influence of porosity, layer geometry and horizontal reinforcing sheets. In homogeneous samples the orientation of lines of zero extension in the maximum-shear plane depended on porosity but not on current strain or inherent anisotropy. Inherent anisotropy did not affect the stress-dilatancy relationship, nor did changing its axes affect the virtual coincidence of stress and strain rate axes. But pre-failure strains were largely influenced by inherent anisotropy at both...