THE USE OF DIGITAL IMAGE-PROCESSING IN MONITORING SHEAR-BAND DEVELOPMENT

A new technique involving sample preparation, video imaging, and image analysis has been developed to observe the kinematics of shear bands when geomaterials are subjected to a general state of combined stress. The technique provides an effective, low-cost, and non-invasive way t o monitor the development and measure the deformations inside and outs ide the shear bands. Its capabilities are demonstrated through a serie s of drained tests in which thin hollow cylinders of sand are subjecte d to combinations of hydrostatic, axial, and torsional stresses. It is shown that the deformation within the shear band is different from th e global one and the one in its vicinity. For sand specimens with the same configuration, density, and confining pressure, the initiation, o rientation, and thickness of shear bands depend on the loading path.