TBM disc cutter is pressed on the rock surface to be broken by the hydraulic system of the machine. In the process of working, the disc cutter rotates around its own axis, and at the same time it revolves around the central axis of the cutter head as the cutter head rotates. Under the combined action of the rotating torque of the cutter head and the vertical thrust of the propulsion cylinder, the disc cutters distributed on the cutter head cut out a group of concentric circles on the tunnel face. When the compressive strength of the rock is lower than the thrust of the cutter head, the rock will be directly broken by the cutter blade, thus forming multiple concentric grooves. With the advance of the cutter head, the groove depth gradually deepens, and the blade penetrates into the rock, forming crushing zones and radial cracks. Under further pressure, when the hob spacing meets certain conditions, the surface crack of the adjacent rock mass expands gradually, and finally the rock between the adjacent concentric grooves collapses, and the rock breaking process of the disc cutters is completed.