ZHANG Mengqi, GOU Bin, DENG Yu, DUAN Wenjun, MO Jiliang, ZHOU Zhongrong
The tunnel boring machine (TBM) is one of the key equipment used in long tunnel construction, which plays an important role in Sichuan-Tibet railway and other major national strategic projects. However, TBM still suffers some problems in hard rock stratum, such as large thrust, slow tunneling speed and serious cutter wear, which need to be solved urgently. The feasibility of controlling the cutter-rock contact based on the cutter surface structure design is discussed, and a spiral-grooved disc cutter is designed. The rock cutting efficiency of the new cutter under different penetration depth and rock types is studied by using linear rock cutting experiments, and the rock breaking mechanism is explained by using the particle flow discrete element numerical simulation. The results show that the spiral grooves on the surface of the cutter can reduce the cutting force, but has only minor effect on the total volume of rock fragments, so it can significantly reduce the work done by the cutter, and improve the energy utilization efficiency of rock cutting process. The reason is that the spiral groove optimizes the rock stress distribution so the rock under a groove is broken by tensile stress, i.e., rock fragments are formed by the interpenetration of cracks, which reduced the number of rock powder, alleviate the excessive degree of broken rock, and finally the cutting load and energy consumption are reduced.
