New Method for Studying Rock-Breaking Mechanism by Disc Cutters

Gaining a thorough understanding of the theoretical principles of rock breaking with a disc cutter is a critical issue in tunnel boring machine (TBM) technology. To fully consider the complexity and importance of the basic principles of rock breaking during tunnel excavation, in this paper we use a new method, the smooth particle hydrodynamics (SPH), to study the rock-breaking mechanism and verify its accuracy and feasibility. Using the SPH method, we induce the rock fragmentation process with two cutters in synchronous and sequential orders. The results show that when the cutters act on rock sequentially, the second indentation influences the crack evolution of the first indentation. With increased cutter spacing, the second crack gradually becomes independent of the first crack. Under synchronous action of the two cutters, a bursiform nucleus is generated beneath the cutters and the area of the nucleus increases with increased cutter spacing. Whether the cutters act on the rock sequentially or synchronously, we found the optimum cutter spacing of our chosen rock type to be 60 mm. Our analyses results show that the efficiency of sequential rock cutting is superior to synchronous cutting, both with respect to crack evolution and cutter force. © 2017, Tianjin University and Springer-Verlag Berlin Heidelberg.