A numerical study of spalling and related rockburst under dynamic disturbance using a particle-based numerical manifold method (PNMM)

In this paper, the spalling failure of rock materials and spalling-induced rockbursts in tunnels are numerically investigated using a particle-based numerical manifold method (PNMM). The ability of PNMM for modelling spalling failure of rocks is validated in both one-dimensional (1D) and two-dimensional (2D) cases. The thickness of the first spall in rock bars and the spalling fracture pattern in rock plates are in good agreement with the theoretical analysis and numerical solutions in the literature. The values of spall strength at different loading rates are calculated by the particle velocities on the free surface of rock bar. Afterward, the rockburst in tunnels triggered by dynamic disturbance is simulated by the validated model. The mechanism of rockburst under this condition is proven to be closely related to spalling failure. The effect of the static in-situ stress on rockbursts are considered. Modelling results reveal that rockbursts are most likely to take place when the dynamic disturbance comes from the direction of the higher in-situ stress. Parametric studies also indicate that the larger difference exists between the horizontal and vertical in-situ stresses, the more severe rockburst could be triggered.