The analysis of different partial wear degrees of cutter on the rock-breaking effect

When the tunnel boring machine (TBM) is engaged in rock-breaking operations, the cutters are subject to wear due to the harsh underground environment. This study aims to investigate the effects of cutter wear on rock-breaking force and overall rock fragmentation efficiency. Firstly, a three-dimensional simulation model of the cutter breaking rock is generated through PFC3D. Then, the rock-breaking force, specific energy consumption and the internal crack breaking mode of the rock are studied under different partial wear degrees of the cutter. Finally, the simulation results were verified and analyzed through indoor scale-down experiments. The research results show that: 1) When the partial wear of the cutter is 8%, the normal force and tangential force increase by 29.1 kN and 12.2 kN, respectively, compared to those without wear. 2) The unit specific energy consumption increases continuously with cutter partial wear. At the 8% wear threshold, the inter-cutter synergistic effect is completely lost, and 91% rock ridge are formed. 3) When the partial wear occurs on the cutter, it will cause a change in the rock fragmentation form, from intergranular cracking to transgranular cracking.