Rock-breaking performance of cutters of tunnel boring machine in broken coal rock formation

This paper aims to design a suitable method to analyze the relationship between the rock-breaking performance and tunneling performance of the cutters of tunnel boring machine (TBM). Considering the cutting discontinuity in broken coal rock formation, the authors put forward a simulation method for the rock-breaking performance of TBM cutters. The material properties of broken coal rock with low mechanical strength and poor uniformity were described by a linear elastic constitutive model and a Drucker-Prager plastic model. The variations in the cutting force with cutting depths (5, 10 and 15mm) and rake angles (5, 10 and 15°) were observed through the simulations, aiming to disclose the mechanical nature of the contact, extrusion and peeling of the coal rock under the action of the cutter. The results show that a high cutting depth and a small rake angle are favorable for tunneling efficiency, but unfavorable for tunneling safety. Overall, the optimal cutting parameters were determined as the cutting depth of 10mm and rake angle of 15°. Our simulations were proved valid through comparison with the results of Evans' cutting resistance model for wedge cutters. The research results shed new light on the research into the TBM cutting of unstable coal rock. © 2020 WITPress. All rights reserved.