Abstract
A laboratory investigation has been carried out into the effects of initial anisotropic fabric and b=(σ2'-σ3')/(σ1'-σ3') on the strength and deformation characteristics of air-pluviated Toyoura sand. Drained tests in triaxial compression (b=0.0), in plane strain compression (b≒0.2∼0.5) and in triaxial extension (b=1.0) were performed at different directions of principal stresses with respect to the deposition direction. The strength in triaxial extension was found to be strongly influenced by failure modes. The inherent anisotropy in strength and the effects of both the parameter b and the failure mode on strength are portrayed in the form of a three dimensional surface having the axes of φ, b and the angles ω and ξ;ω and ξ represent the deposition direction with respect to the directions of σ1', σ2' and σ3'. It was found that φ is rather insensitive to the change in b when the one of the planes of the maximum stress obliquity is in parallel with the bedding plane. The deformation characteristics including the stress-dilatancy relation are discussed in a similar way as for φ.
