The influence of particle rolling and imperfections on the formation of shear bands in granular material

This paper examines the development and evolution of shear bands in granular assemblies when particle rolling and imperfections are taken into account. Simulated biaxial tests in two-dimension are conducted using the discrete element method. The progressive development of rotational angles and effective strain are presented to describe the emergence and evolution of shear bands in biaxial tests. The simulated results reveal that when rolling resistance is taken into account in DEM, the development of shear bands is more distinct as the evolution of the minor shear bands is limited while the major shear bands are preferably promoted in granular materials, and that the local rotating bearings not only influence the onset of shear bands and the width of the shear bands, but also decrease the resistance and reduce the strength of the granular material. Also, it is demonstrated that the primary shear bands initiate from the imperfect areas and develop preferentially along the direction of imperfections. Therefore, the emergence and development of shear bands, which will result in a decline in strength and eventually lead to instability and destruction of the material, can be effectively simulated when rolling resistance is incorporated in DEM and the initial distribution of imperfections in the granular material is defined.