Characteristic study on the failure of shear bands of geomaterials with damage and strain softening effect

The damage critical curved surface is derived by considering the related effect of isotropic damage and degradation of cohesion and internal friction angle of Mohr-Coulomb strength law. The characteristics of axial stress-displacement curve, axial-lateral displacement curve, networks of shear bands and the change with degree of damage, confining pressure, poisson's ratio are investigated numerically by monitoring the stress-displacement values in the process of deformation of samples under plane strain and different initial conditions. It is shown that Peak strength, residual strength, and its axial displacement depend on confining pressure. The networks of shear bands begin to 11 phase of elasticity, develop in soften phase, and shaped in the phase of residual strength. When there is confining pressure, the networks of shear bands is transformed to a pair of predominant conjugate localization band shaped X. The ratio of shear strain is intensively concentrated in the center of shear band. When there is not confining pressure, the shear deformation is only concentrated on single localization band that passes through the right and left boundary of sample. After the shear band is absolutely in shaped, the lateral displacement that passes through localization band keeps transitory invariable, then increases linearly, thus the lateral displacement outside the localization band keeps invariability all times, it is shown the sample begins to glide over relative rigid body. The sample can endure certain residual load after the shear band is in shaped.