Model for penetration of the TBM disc cutter under laser pre-drilling based on stress concentration in a circular hole and its test verification

The laser generator is installed on the cutterhead of the tunneling boring machine (TBM), and the high-energy laser is used to assist the TBM tunneling operation, which is expected to achieve the purpose of thermal-mechanically efficient rock breaking in theory. For the laser-assisted rock breaking by disc cutter, based on the method for elastic stress state of the stress concentration theory in a circular hole and the cavity expansion model, a theoretical model for rock penetration by cutter under laser pre-drilling is established considering the effects of dense core, and it is theoretically analyzed. Subsequently, the laser-assisted disc cutter indenter penetration tests under confining pressure are carried out to verify the theoretical model. The results show that both the edge width and the hole spacing have effects on the vertical force, and that when the hole spacing is small, the theoretical model is no longer applicable. Through comparative analysis of the theoretical model and the test results, the vertical force has the same change trend with change in the hole spacing and is relatively consistent. The theoretical model is of certain accuracy.