Influences of Microwave Irradiation on Rock-Breaking Efficiency of a Reduced-Scale TBM Cutter

To explore the influences of microwave irradiation on the rock-breaking efficiency of tunnel boring machine (TBM) cutters, a multimode cavity with a microwave power of 2100 W was used to conduct microwave irradiation tests on Chifeng basalt for different durations. A combined abrasion test device for the reduced-scale SP3-I TBM cutter was adopted to conduct cutter wear and rock-breaking tests on basalt samples before and after microwave irradiation. Influences of microwave irradiation on the wear loss of the reduced-scale TBM cutter, rock removal, cutting force, and specific energy were investigated. The results show that the wear loss of the reduced-scale TBM cutter linearly reduces while the rock removal linearly increases with increasing exposure to microwave irradiation. When the penetration depth and the cutter spacing are fixed, the cutting force and the work done by the cutting force exerted by the reduced-scale TBM cutter decrease linearly with increasing exposure to microwave irradiation. The rock-breaking specific energy decreases with increasing exposure to microwave irradiation in an exponential manner. These results indicate that microwave irradiation can prolong the service life of the TBM cutter in the rock-breaking process, reduce the required thrust and torque of the cutter, and improve the rock-breaking efficiency of the TBM.