Abstract
Inherent and stress state-induced anisotropy in the elastic deformation properties of granular materials were investigated experimentally. Both axial and lateral principal strains of large square-prismatic and small solid cylindrical specimens were measured locally. Very small strain-amplitude cyclic normal stresses were applied in the vertical and horizontal directions at various isotropic and anisotropic stress states. Elastic deformation properties are inherently anisotropic with the Young's modulus being larger in the vertical direction than in the horizontal direction at isotropic stress states. The Young's modulus is stress state-dependent, becoming more anisotropic as the stress state becomes more anisotropic. The elasticity is of hypo-elastic type. Deformations do not become totally elastic even after the application of a large number of stress cycles of relatively large amplitude along a fixed stress path.
