Fracture mechanism of tunnel surrounding rock induced by blasting disturbances: Experiments and numerical simulations
Jianpo Liu, Fengtian Li, Xiaonan Wang, Yingtao Si, Yandi Fan, Zixuan Zhang, Yongxin Wang
Abstract
The inversion of the source mechanism is a critical step in revealing and understanding the mechanisms of rock mass failure and guiding the prevention and control of ground pressure disasters. Under conditions of high stress and strong blasting disturbances, the formation, clustering, and interconnection of internal cracks in the surrounding rock of tunnels are highly likely to induce rock mass failure. Investigating the failure mechanisms of tunnel surrounding rock induced by strong blasting disturbances is essential for achieving effective tunnel protection. In this study, acoustic emission (AE) monitoring technology was employed to capture micro-fracture signals from the surrounding rock in real time. The RA-AF ratio method was utilized to classify crack types, while discrete element numerical simulations were conducted to analyze crack propagation patterns under dynamic disturbances. The results indicate that tensile-type cracks dominate during the static stress-controlled stage of tunnel failure, whereas blasting disturbances significantly accelerate shear crack propagation. Stress waves traveling in different directions produce tensile reflection effects in straight wall regions, leading to the interconnection of shallow cracks on the blast-facing side and the formation of macroscopic fracture zones. Based on these findings, optimization strategies for support design are proposed. Radial constraints should be enhanced on the blast-facing side to suppress shallow surrounding rock deformation, and support depth should be extended along principal stress directions to mitigate rock mass damage and diffusion caused by blasting disturbances. © 2001 Elsevier Science. All rights reserved • The characteristics of energy differences were taken into account during the classification of tensile and shear cracks • The surrounding rock of the roadway exhibited a transformation from tensile to shear fracture mechanisms. • Disturbance waves from different directions induced heterogeneous expansion of the damage zone.