Abstract: To study the rock fragmentation properties by the shield disc cutters and how the disc cutter structure parameters (the blade width and the blade angle of the disc cutter) influence the rock fragmentation properties by the disc cutters, numerical simulation of the rock fragmentation by the disc cutter is developed. Based on discrete element method (DEM), a series of two-dimensional numerical modeling between the rock and the disc cutter are established. This study researches the relationship among penetration、the cutting force and the crack number in the process of the disc cutter intrusive the rock. And then the law between the disc cutters structure parameters and fracture characteristics of rock has been discovered by a simulation example. The results show that the extension of the crack in the rock is related to the forces of the disc cutter. The cutting forces in the rock-fragmentation increases at first and then decreases. The phenomenon above proves the rock's jump break property. It demonstrates that the additional stress in the rock is stress bubble which is downward. Meanwhile, the stress bubble disperses unlimitedly under the action of the disc cutter. Besides the stress bubble is symmetric. What’s more, in the blade working region, the additional stress reaches a maximum when it is close to the edge of the disc cutter. While the maximum additional stress decreases when the penetration of the disc cutter increases. When it is far away from the disc cutter edge, the additional stress in additional stress bubbles form decreases gradually in layers until the additional stress reaches 0 MPa.When the blade width of the disc cutter is chosen properly, which arranges from 10 mm to 15 mm it can not only avoid the thrust force being too large but also improve the efficiency of the disc cutter working in the rock fragmentation. The crack in the rock occurs under the blade of the disc cutter and the crack propagation is downward and it is axial mainly. When the angle of the blade is between 10° and 20°, it can not only reduce the wear of the disc cutter but also improve the efficiency of the disc cutter.

Key words: disc cutter, rock fragmentation mechanism, discrete element method (DEM), numerical simulation