Rolling resistance at contacts in simulation of shear band development by DEM

To simulate numerically the microstructure of shear bands, the distinct element method was modified such that the effect of rolling resistance at contacts could be taken into account. To this end, the relative movement by rolling is related to the relative rotation between two particles with a common contact, which makes it possible to generalize the conservation law of angular momentum for a more general case than the moments can be transmitted through contacts. Not only the generation of large voids inside a shear band but also the high gradient of particle rotation along the shear band boundaries can be reproduced, in a manner quite similar to those of natural granular soils, when the rolling resistance at contacts is considered. The development of columns is a common feature that appears in the strain hardening process, and buckling of the columns parallels the development of shear bands. The generation of large voids and the high gradient of particle rotation are produced as a result of the buckling of the columns.