Abstract: To verify the efficient rock breaking ability of high-energy laser technology using for tunnel boring machines (shorted for TBM) disc cutters (hereinafter referred to as disc cutters), taking the basic movement form of the hob in the process of rock breaking-rock intrusion as the research object, a reduced scale hob indenter is prepared with a ratio of 1:8 (the following is the hob indenter) referring to the 17 inch (432 mm) engineering hob, orthogonal tests of rock invasion by hob indenter L20 (4×5) with laser assist and comparative tests without laser assist were carried out with different hole spacing (2, 3, 4, 5 mm) and cutter-hole spacing (3, 4, 5, 6, 7 mm) as variables. The experimental results show that with the increase of indenter-hole distance, both volumes of rock breakage and rock fragmentation size increase; with the increasing laser hole distance, rock breakage volume, vertical forces and the difficulty of rock breaking decrease, while rock fragmentation size and specific energy increase. The optimal indenter-hole distance and laser hole distance are 6 mm and 3 mm respectively. Compared with the traditional rock-breaking method by disc cutters, laser-assisted rock cutting would promote the generation of rock tensile cracks, and improve the rock-breaking efficiency of indentation by the cutters. The research results also show the prospects for application of the proposed laser-assisted rock cutting model to TBM tunneling under the extremely hard rock grounds in the future.

Key words: tunnel boring machine (TBM), disc cutter, laser-assisted, rock drilling, indentation