Development of a Real-Time Monitoring and Calculation Method for TBM Disc-Cutter's Cutting Force in Complex Ground

Cutting force is an essential parameter of the operating state of tunneling boring machines. In this study, a real-time cutting force monitoring method is proposed for widely used disc-cutters. A microcylindrical strain gauge is embedded in predrilled small boreholes in the bottom and side surface of the two C-shaped cushion blocks on the cutter saddle. The strain gauges are protected by a glue seal, and the sensor leads are protected using a groove and covered by wear-resistant steel. The strain is measured using a wireless strain node and transmitted from the strain node to the wireless gateway connected to a computer. Then, the strain-force relationship of the cushion block is fitted using a laboratory static calibration test. The load on the cushion block is calculated based on the measured cushion block strain. Subsequently, considering the cutter system's vibration, a multi-degree-of-freedom coupling vibration differential equation of the cutter system is established. The mass matrix, stiffness matrix, and damping matrix of the cutter system are also determined. Finally, a Wilson -0 inverse analysis method is put forward to calculate the cutter's external load. The developed real-time cutting force monitoring method will not affect cutter replacement, and the cushion block equipped with sensors can be reused. The cutting force identification method, which considers the cutter system vibration, is rigorous in theory, and a useful numerical inverse analysis calculation method is provided.