Experimental research on the rotary rock-breaking effect of tunnel boring machine cutters assisted by microwave irradiation

Abstract

To deeply analyze the rock-breaking effect of tunnel boring machine (TBM) cutters assisted by microwave irradiation, rock-breaking experiments were conducted on microwave-irradiated rocks using reduced-scale TBM cutters. Influences of parameters including the microwave exposure time, microwave power, cutter spacing, same rolling distance (different rock-breaking depths), and penetration rate on rock-breaking marks, rock removal, wear loss of cutters, average cutter thrust, average cutterhead torque, and rock-breaking specific energy were explored. Research results show that under the same rotation diameter, increasing the microwave exposure time and microwave power decreases the wear loss of cutters, average cutter thrust, average cutterhead torque, and rock-breaking specific energy while increases the rock removal. If the cutter spacing is too large, the rock between adjacent cutting marks cannot be effectively exfoliated, the average cutter thrust and cutterhead torque enlarge, and the rock-breaking efficiency reduces. The wear loss of cutters is directly proportional to the rock-breaking depth. Under the current experimental conditions, using a large rock-breaking depth can exfoliate rock debris and improve the rock-breaking efficiency. A high penetration rate reduces the rotation number of the cutterhead, promotes the generation of rock debris, enlarges the rock removal, and improves the rock-breaking efficiency.