Development and in-situ application of a real-time monitoring system for the interaction between TBM and surrounding rock

In this study, a real-time monitoring system for the interaction between TBM (Tunnel Boring Machine) and surrounding rock is developed, in which the focus is on the cutter-head vibration, and the interaction between the surrounding rock and the shield. The monitoring system consists of sensors, data acquisition subsystem, remote data transmission-storage subsystem and data analysis subsystem. A program is developed to carry out unattended operation of the monitoring software. Further, it can transmit the data synchronously from inside the tunnel to the system outside the tunnel, as well as give feedback information of any operation error to the users automatically. The feasibility, stability, durability of the developed monitoring method has been validated. Subsequently, the time-domain and spectral frequent-domain analysis methods for the accelerated velocity of cutter-head vibration are put forward. Further, the back-calculation analyses method for the surrounding rock pressures acting on the shield and shield jamming warning approach is also developed. Then, the developed monitoring method has been implemented on the double-shield TBM in China's Lanzhou Water Resource Project. Many evolution rules have been obtained. Firstly, the cutter-head vibration monitoring results show that: (a) the cutter-head vibration is significantly correlated with the TBM advance parameters and the geological conditions; (b) the cutter-head vibrates intensely during TBM restarting after a stoppage or entrapment; (c) the cutter-head vibration intensity increases with the increasing cutter-head rotational speed and penetration rate. Secondly, in-situ monitoring of the surrounding rock pressures acting on the shield manifests that: (a) the surrounding rock pressures acting on the shield is non-uniform, which increase with the growing distance from the tunnel face; (b) the contact scope enlarges from the front shield to the rear shield gradually with time, and the surrounding rock loads acting on the shield increases simultaneously; (c) the squeezing pressures acting on the shield decrease and then return to the relatively small pressures after the relief countermeasures were conducted on the trapped TBM. The measured data give insights on the intense cutter-head vibration warning and shield jamming prediction. Furthermore, the verifications, significances, advantages, weaknesses and future improvements of the monitoring system are discussed.