Shear Banding in Coarse Sands Under Combined Stresses.

The phenomenon of shear banding in soils has been studied over the last few years at Case Western Reserve University. Prior research was performed on cohesive and fine-grain, angular soils. To complete the study, a coarse-grain sand was used to determine the effect grain size has on the propagation of shear bands. Many state-of-the- art techniques were used to collect the necessary data these include digital imaging programs and constant mean stress testing devices. Several different variables were examined to determine the effect they have on the development and propagation of the shear band. Some of these parameters include relative density, stress path, and confining pressure. The genesis of the slip plane and the eventual direction of the shear band was monitored using video cameras. At regular times during the testing process, snapshots from these cameras were taken and stored as VGA images on a computer. The images were then digitally traced using specifically designed software packages. With the images digitally recorded, a great deal of information could then be calculated such as the angle of the slip plane and the strains in and around the shear band.