ANISOTROPY AND STRESS DISTRIBUTION IN SAND

Abstract

Sand has both inherent and induced anisotropy. The former is produced by sedimentation and the latter occurs in shear. Degree of the anisotropy is evaluated by means of the deformation modulus ratio n = E_x/E_z, and the case n <1 is treated.
Deriving the solutions of stress and displacement in a cross-anisotropic soil, effect of n on the stress and surface settlement in sand is examined. The results show that the stress and surface settlement tend to increase near the load in case of n<1. This stress increase in plane strain case is smaller than that in axial symmetry. It can be known that the author's stress solution is not coincidence with Wolf's.
From the evidence that a radial stress field is formed in the plane strain case, it can be considered that the value n will be partly responsible for the measured concentration index in Frölich's formula.
Usefulness of the anisotropic stress-strain laws for expressing the dilatancy of soil is emphasized.