Micro-mechanical Observations of Strain Localization in Granular Soils During Simple Shear Loading

Abstract

This paper examines the micro-mechanical origins of strain localization in granular materials during simple shear loading using the two-dimensional Discrete Element Method (DEM) as implemented in the Particle Flow Code (PFC). A key feature of the DEM model used in the study is the implementation of a rolling resistance component in the contact behavior between particles. Analysis of the results of the DEM study was performed in terms of the evolution of force chains, buckling of columns of particles, particle rolling, and formation of voids in the shear band. The results show that at bifurcation fewer force chains carry the loads inside the shear band, and as the frictional resistance between particles is exceeded, the force chains collapse. This collapse is seen in the buckling of columns of particles in narrow zones in the shear band. High degrees of particle rotations and large voids are produced in the shear band as a result of particle column buckling.