Optimal normal force analysis of disc cutter based on test and characteristic particle size theory

Abstract The disc cutter is one of the most TBM cutting tools because of its excellent rock‐breaking capacity. In order to improve the efficiency of the disc cutter, determining the appropriate normal force is an effective solution. The characteristics of rock chips formed by disc cutter are important indicators to comprehensively reflect the rock breaking efficiency. In order to research the relationship between characteristic particle size and the optimal normal force of the disc cutter, the linear cutting test is carried out and the effects of six sets of TBM disc cutter penetrations on the particle size distribution are investigated. The data of rock chips from test and the characteristic particle size theory are used to investigate the relationship when the TBM energy consumption is consistent with Kich similarity theory, Bond hypothesis and Rittinger new surface theory. It is found that the relationships between the rock‐breaking consumption energy, characteristic particle size and penetration are both in accordance with the quadratic function. Moreover, the formulas between the optimal normal force and the characteristic particle size are obtained, which provide theoretical basis for excavation construction in the similar stratum.