A peridynamics study for the free-surface-assisted rock fragmentation caused by TBM disc cutters

The free-surface-assisted rock fragmentation caused by TBM disc cutters is capable of overcoming the difficulties brought by abrasive or high strength hard rock stratum in tunneling practices. In this work, Peridynamics is proposed to study the phenomenon of free-surface-assisted rock fragmentation caused by disc cutters. Peridy-namics can avoid the drawback of finite element methods in simulating complex rock fractures in continuum, and the inconvenience of discrete element methods whose parameters are often hard to calibrate. Through numerical examples, we demonstrate the capability of Peridynamics method in simulating rock fragmentation with only two calibration parameters. With the Peridynamics framework, we have captured the whole process of rock fragmentation caused by disc cutters, and we also study the size variation of 3D rock fragments with different free-surface height and distance from cutter to free surface, and the influences of spacing and loading styles of double cutters on fragmentation patterns. The paper provides a new and reliable numerical approach for modeling free-surface-assisted rock fragmentation, and can be used in optimizing the size of rock fragments, and designing cutter spacing of double disc cutters in the tunnel engineering.