A Fine Simulation Analysis of Rock Fragmentation Mechanism of TBM Disc Cutter with DEM

Abstract

Research on rock fragmentation mechanism is significant for TBM projects. To study the influence of penetration on the disc cutter force, a numerical simulation was conducted using the software MatDEM based on Discrete Element Method (DEM). A 19 in. disc cutter model was established. Four rock materials characterised by different strength properties and two layered rock combinations were assigned to the large-scale rock specimen. The rock breaking processes of single cutter were simulated at penetrations of 2, 4, 6, 8 and 10 mm respectively. Through the monitoring and analysis of cutter forces and specific energy (SE) changes, it is found that for the same type of rock material, the average normal force and rolling force both increase as the penetration increases, but the growth trends have shown a significant difference due to the rock strength properties. The SE can be significantly affected by penetrations and there is an optimal penetration, respectively, to minimize the SE value for different types of rock. In addition, the dissimilar rock combinations have a significant impact on the cutter forces. To verify the simulation law of disc cutter forces with respect to penetrations, the linear cutting machine (LCM) test has been carried out. The consistency of the comparison results of the two methods indicated that combining the simulation of MatDEM with the LCM test can explore the rock fragmentation mechanism of the disc cutter more deeply and comprehensively.