Design and application of forces testing for TBM disc cutter in indoor experiment

To enhance cutting system’s stiffness of linear cutting machine and obtain reliable rock breaking forces of disc cutter, this study proposes a strain-gauge-based measurement method in three bridge circuits attached in a column-frame type cutter holder. By rationally arranging strain gauges on its four columns to form three independent full bridge circuits, the normal, rolling, and side forces on disc cutter are able to be measured separately. The finite element analysis confirms the sufficient strength and high rigidity of the cutter holder and guides the optimal placement of strain gauges. Furthermore, the mapping relationships between the three-directional rock breaking forces and the output strains from three bridge circuits are determined with the calibration experiments. Finally, cutting tests on granite under different cutting parameters are performed and testing results are compared with CSM model results. It demonstrates that this method can effectively measure dynamic rock breaking force signals. Meanwhile, it reveals that the rock breaking forces measured by this method, particularly under larger penetration depths, are significantly larger than those obtained by the CSM model since the cutting system in the experiments has sufficient stiffness. The proposed method can provide accurate and reliable force data for the design of the cutter and the entire TBM machine.