Abstract: In order to evaluate the rock breaking performance of tunnel boring machine (TBM), feedback the rock breaking load of the disc cutter, and warn the risk of the TBM jamming, the rock breaking coefficient is used to represent the rock breaking characteristics of TBM, and the cutting coefficient is used to represent the rock breaking characteristics of single disc cutter. The rock breaking coefficient reflects TBM thrust and torque correlation on a macro scale, on the other hand, the cutting coefficient reflects the correlation between the disc cutter vertical force and rolling force on a meso scale. By deriving the relationship between the TBM rock breaking coefficient and the disc cutter cutting coefficient, it is found that the rock breaking coefficient and the cutting coefficient are numerically equal, and only related to penetration and disc cutter diameter. By validating multiple TBM engineering field data, it is found that both TBM rock breaking coefficient and disc cutter cutting coefficient show power function with the penetration. While, the TBM rock breaking coefficient is obviously smaller than disc cutter cutting coefficient, but the two are highly linear, which shows that the theoretical derivation of the relationship between the rock breaking coefficient and the cutting coefficient is correct. The correlation among parameters such as rock breaking coefficient, cutting coefficient and penetration established in this paper is of great benefit in predicting and evaluating rock breaking performance of TBM.

Key words: tunnel engineering, rock breaking performance, tunnel boring machine（TBM）, rock breaking load, jamming warning