Investigation of crack inhibition mechanism by anchoring: Insights from discrete element simulation and force chain analysis

In order to deeply reveal the anchoring mechanism of bolt to granites, coupled modeling technology of finite difference method (FDM) - discrete element method (DEM) is used to develop a numerical anchored sample. The differences in term of mechanical and geometric size of various minerals in granites can be restored at a three-dimensional scale. The force chain network realizes multi-level classification and quantitative analysis. It is found that under the uniaxial compression condition, the level of force chains of the anchored sample is greater than that of the unanchored sample. Among all minerals, quartz has the highest average value of force chains, which is mainly due to its highest micro-parameters. The anchoring reinforcement mechanism is revealed based on the force chain information. Both the sum value and average value of force chains in anchored samples consistently exceed those of unanchored samples at all crucial loading moments. The number of cracks in the anchored sample is smaller than that in the unanchored sample. The anti-cracking resistance of the end region is significantly improved. The crack distribution and stress distribution of the whole anchored sample are more uniform, which fundamentally improves the bearing capacity. The conclusion can provide some reference for the stability analysis of surrounding rock and the determining of bolt support scheme.