Rock Breaking Performance of Two Disc Cutters of Tunnel Boring Machine for Safe Tunneling in Unstable Coal Rock Stratum

Abstract

In unstable coal rock formations, the rescue channels should be constructed through safe and efficient tunneling. The rock breaking performance of the tunneling equipment directly hinges on the cutter-head layout. Focusing on the conditions of unstable coal rock formation, this paper adopts the extended Drucker-Prager (D-P) plastic model to define the properties of bedrock materials of the coal rock with low mechanical strength and poor homogeneity. Then, a finite-element model was established on ABAQUS for the coal rock cut by two disc cutters, and used to simulate the breaking of the coal rock and the peeling of slags from the bedrock. On this basis, the authors analyzed the influence of cutter spacing (30, 35, 40, and 45mm) over cutting force, rock breaking amount, and specific energy under two cutting methods: simultaneous cutting and sequential cutting. Finally, a cutter deployment strategy was designed for safe and efficient tunneling in unstable coal rock formations. The results show that: Under simultaneous cutting, as the cutter spacing increased from 30 to 35mm, the rock breaking amount increased, while the specific energy declined; as the cutter spacing further rose from 35 to 45mm, the rock breaking amount dropped, while the specific energy increased. Under the coal rock conditions in our research, the optimal cutter deployment strategy is: simultaneous cutting with cutter spacing of 35mm. The research results provide theoretical support for the cutter-head design of rescue equipment for collapsed coalmines.

Coal Rock Breaking Simulation and Cutting Performance Analysis of Disc Cutters

“…Labra et al [16] combined discrete element simulation with FEA software to explore the difference between rock breaking with pre-cutting and that without pre-cutting in pressure distribution. Guo et al [17] constructed a finite-element model of coal rock breaking with two cutters, and examined how the cutter spacing affects cutting force, degree of fragmentation, and specific energy under simultaneous cutting and sequential cutting.…”