Real-time monitoring and early warning approach of TBM jamming and its application

The deformation of surrounding rock is prone to be large when TBM tunnelling into deep and weak ground, and the surrounding rock may squeeze TBM shield easily, then the jamming accident will happen. In order to reduce the risk of TBM jamming during tunnelling process, the monitored strain of internal shield surface was taken as the early warning index, and a real-time monitoring and early warning approach of TBM jamming was proposed. Based on the automatic task processing program and optical fibre communication technology, the proposed approach was equipped with functions of unattended operation, automatic data acquisition and transmission, remote control and automatic self-test. This monitoring and early warning approach was applied to the TBM tunnel of Lanzhou water resource project. Combined with the investigation report of the TBM jamming accident, the field monitoring data and operation parameters were analysed. The results show that the proposed approach can provide a potential effective way for early warning of TBM jamming. At the same time, according to the spatial and temporal variation law of the strain at each measuring point of internal shield surface, the direction and variation trend of the load acting on external shield surface can be speculated, which can provide references for tunnelling parameter adjustment and accident treatment during tunnelling process. © 2019, Science Press. All right reserved.