Effects of Driving Parameters on TBM Dynamic Response and Cracking of the Disc Cutter Ring: A Case Study

Rock excavation by disc cutters is widely employed in tunnel boring machine (TBM). Rock-breaking impact load acted on disc cutters especially when cutting heterogeneous rock, which if not properly dealt with, may induce cracking of disc cutters. The impact load is excitation source of the TBM dynamic response and it is feasible to analyze the law of impact load based on dynamic response. In this study, a set of real-time dynamic response monitoring and analysis system was installed in a slurry TBM of a water delivery tunnel in Beijing to analyze the impact load action law that induced cracking of the cutter ring, and a series of in-situ tunneling experiments were carried out. The time-domain and frequency-domain characteristics of acceleration response were deeply investigated. The results show that compared with the static parameters, such as thrust and torque of the TBM, the acceleration response is extremely sensitive to changes of the driving parameters (advance speed, cutterhead rotating speed and penetration rate) and rapidly attenuates from the cutterhead to the shield tail of the machine. In the full section quartzy sandstone stratum, the acceleration response of the cutterhead is significantly increased with the slight improve of the penetration rate and the rotating speed and the effect of the penetration rate is larger. The acceleration response is small during the TBM tunneling with low penetration rate–high rotating speed, which is also applicable to the broken stratum. The results of dynamic response test indicate that the impact load resulting in cracking of cutter ring can be effectively reduced by three methods: reducing penetration rate, reducing rotating speed and tunneling with low penetration rate–high rotating speed. The statistical data of cutter wear validate this conclusion. The findings in the engineering practice can provide valuable references for similar TBM construction.