Distinct element analysis of mechanism of rock fragmentation induced by TBM cutting rock mass with a couple of cross joints

Abstract

In this study the Distinct Element Method (DEM) with a size-dependent bond contact model was employed to investigate the fracture mechanism induced by TBM cutting in rock mass with a group of cross joints, where the effect of joint inclination angle under two cutters was analyzed. The center joint outcrop is fixed at a distance of 20 mm with the rock mass center. The DEM results show that the process of rock fragmentation can be divided into three stages: loading stage, unloading stage and residual jumping stage. The peak normal thrust decreases gradually with the decrease of joint angle α. During the process, the number of bond failure increases gradually with the increase of invasion depth. There are two distributions of bond failure in different joint angles. One is the bond failure concentrates between the cutter and the shallow joint. The other one is the bond failure crosses the shallow joint and reaches the next joint