Shear banding in a sedimentary soft mudstone subjected to plane strain compression

A plane strain compression (PSC) testing system to observe shear banding in softrock was developed. The deformation characteristics of shear band in a sedimentary soft mudstone were evaluated by locally measuring axial and la teral deformations of specimens in drained PSC tests. Shear deformation and dilatancy of sheer band that occurred between the peak stress state and th e start of the residual stress state were on the order of 1 and 0.5 mm. Dil atancy of the shear band continued during the residual stress state, result ing in a high-residual Friction angle mobilized along the shear band. Shear band deformation characteristics of two other sedimentary softrocks were o btained from axial strains measured locally in triaxial compression tests b ased on the stress-state dilatancy relationship obtained from the PSC tests .