<p>Tunnel boring machine (TBM) faces the dual challenges of reduced boring efficiency and increased disc cutter maintenance costs in hard rock formations. Free surface assisted rock-breaking technology shows promising application prospects for enhancing TBM rock-breaking performance. However, different free surface assisted breaking modes exhibit distinct rock breaking characteristics and disc cutter wear behaviour. To systematically study the wear behavior and rock breaking characteristics of the disc cutter under different free surface assisted rock breaking modes, the middle rock breaking mode and the overlapping rock breaking mode were set up, and three installation radii were selected. The annular free surface corresponding to the engineering practice is established by using high pressure water jet, and the rotary cutting experiment is carried out. At the same time, the vertical penetration experiment was carried out and compared with the results of the rotary cutting experiment. The rock breaking load, disc cutter wear mass, rock breaking efficiency, and rock morphology were analysed. The results show that the intensity of load fluctuation of the two rock-breaking modes gradually increases with the decrease of the depth of the free surface, resulting in a corresponding increase in the impact load on the disc cutter. The wear mass and rock breaking efficiency of the disc cutter in the middle rock breaking mode are better than those in the overlapping rock breaking mode. With the increase in the installation radius, the wear mass of the disc cutter increases. The intensity of load fluctuation and rock morphology results of the vertical penetration rock breaking mode correspond to those of the rotary cutting rock breaking. The research findings provide crucial support for selecting TBM disc cutter rock-breaking modes and predicting disc cutter wear, thereby enhancing the safety and efficiency of TBM construction.</p>