Simulation of the Influence of Grain Damage on the Evolution of Shear Strain Localization

Abstract

The influence of grain damage on shear strain localization in a lateral infinite granular layer under monotonic plane shearing is simulated using a micro-polar continuum description. The change of the grading of the grain sizes caused by grain damage is taken into account in a simplified manner by a reduction of the mean grain diameter, which is embedded in the constitutive model as an internal length. It is assumed that a reduction of the mean grain diameter caused by grain breakage and grain abrasion is related to an increase in the pressure, the micro-rotation and the micro-curvature. A reduction of the grain sizes is accompanied by a reduction of the limit void ratios and a reduction of the material against compaction. In the constitutive model the decrease of the mean grain diameter is linked to the so-called solid hardness, which is defined within a continuum description. The proposed concept of reduction of the mean grain diameter and the solid hardness is embedded in a micro-polar hypoplastic model. The results of the numerical simulations show that the reduction of the mean grain diameter has a significant effect on the evolution of the void ratio within the zone of shear strain localization.