DEFORMATION MECHANISM OF SAND IN TRIAXIAL COMPRESSION TESTS

[出版社版]rights: 社団法人地盤工学会 rights: 本文データは学協会の許諾に基づきCiNiiから複製したものである relation: IsVersionOf: http://ci.nii.ac.jp/naid/110003913113/Based on detailed observations by using a microscope and thin section method, a new granular model has been proposed as a basis of theoretical considerations on granular mechanics.The specimen deformed to residual stress state can be divided into three subdomains having each homogeneous fabric, i.e., dead domain, dilated domain and shear domain. The void ratio in the dilated domain becomes equal to 20% relative density at peak stress state whose value represents an unstable particle configuration in a granular material. Concentration of directions (N_i) perpendicular to tangential planes at contacts to the maximum principal stress direction performs an essential role in strengthening granular fabric up to the peak stress state. Relative movements between particles in the shear domain occur principally by preferred sliding along the contacts having N_i inclined to σ_1-direction about 35°, and partially by rolling of each grain to reorient preferred dimensional orientation. Mobilized stress ratio of granular materials when subjected to a deviatoric stress state is found to depend not only upon the interparticle friction angle between grains φ_μ but also upon the parameter representing fabric anisotropy S_z/S_x. Experiments on two kinds of sand show that theoretical equation is closely obeyed by experimental results throughout deformation to failure irrespective of their initial void ratio and initial fabric