Numerical Simulation Study on Rock Breaking Efficiency of Shield Cutters in Large-Size Boulder Strata

Abstract Tearing cutters are generally applied to break rocks when shield tunnelling in the strata with large size boulders. To improve rock breaking efficiency, the processes of tearing cutter impacting rock model are simulated, and the effects of cutter mass, impact velocity and spacings on specific energy of rock breaking are studied. The results indicate that the impact energy rises significantly by increasing the cutter mass or impact velocity. With the increase of cutter mass or impact velocity, the specific energy decreases rapidly at first and then increases slowly. The rock breaking efficiency increases firstly and then decreases, and the specific energy has a minimum value. Under the same impact energy, the rock breaking effect by changing the cutter mass is better than changing impact velocity. When cutter spacing increases, the specific energy decreases gradually and then increases. Once the cutter spacing is optimized, the specific energy of rock breaking is the minimum and the rock breaking efficiency is the highest. The research results can provide reference for the cutter design and layout in the similar strata.