Previous studies have predominantly employed single continuous or discontinuous numerical methods to simulate the tunnel boring machine (TBM) disc cutter rock breaking process, making it difficult to accurately analyze information such as rock debris size, rock debris volume, and specific energy. Therefore, the purpose of this paper is to calibrate appropriate element sizes and penetration rates when using the 2D-FDEM numerical method to simulate TBM disc cutter rock breaking. Additionally, it aims to investigate the effects of cutter blade width, disc cutter spacing and penetration sequence.
By setting different element sizes and penetration rates, their effects on rock breaking effectiveness are investigated. When the element size and penetration rate are sufficiently small, the simulation results stabilize, allowing for the calibration of appropriate element sizes and penetration rates. Additionally, by varying cutter blade widths, cutter spacings and penetration sequences, their respective impacts on rock breaking effectiveness are studied to determine the optimal cutter width and spacing.
The maximum element size should not exceed 3.5 mm, and the maximum penetration rate should not exceed 1.0 m/s. The optimal cutter width ranges from 7.0 to 14.5 mm. Wide-blade cutters can reduce specific energy, expand the failure range of the specimen, and reduce cutter wear. However, wide-blade cutters increase cutter thrust and crack initiation load. Under the conditions studied in this paper, the optimal spacing between adjacent cutters is 10–15 cm when they penetrate simultaneously. However, when there is a sequential difference in the penetration order of adjacent cutters, the cutter spacing needs to be reduced.
The findings of this study provide valuable references for selecting element sizes and penetration rates in subsequent FDEM simulations of TBM disc cutter rock breaking. Furthermore, the results establish recommended ranges for optimal cutter blade width and cutter spacing, offering practical guidance for the design and installation of TBM disc cutters.
