Numerical simulation of rockburst disaster and control strategy of constant resistance and large deformation anchor cable in Gaoloushan tunnel

The Gaoloushan Tunnel in Longnan City, Gansu Province, China, frequently experiences rockburst disasters due to high in-situ stress. Managing rockburst in deep-buried tunnels remains a challenging issue. This paper employs RFPA (Rock Failure Process Analysis) software to establish a calculation model of constant resistance and large deformation (CRLD) anchorages and analyzes the effects of different support methods and pre-stress levels on rockburst. We simulate the process of tunnel rockburst disasters and find that ordinary anchor support incurs rockburst on the right arch waist and arch top, forming a V-shaped explosion pit. CRLD anchor support has several advantages in rockburst control, such as more uniform stress distribution in the surrounding rock, a uniform distribution of plastic zones, less noticeable damage to the tunnel, and effective control of the arch top displacement. The effectiveness of the CRLD anchor support under varying pre-stress conditions shows that a higher pre-stress results in a smaller plastic zone of the surrounding rock and arch top displacement and a lower number of acoustic emission signals, which better explains the excavation compensation effect. Moreover, adding long anchorages in the deep surrounding rock area can better control rockburst and reduce surrounding rock deformation. Based on these findings, we propose a comprehensive control system that combines long and short anchorages and provides the optimal scheme based on calculations. Therefore, by using high-prestress CRLD anchor support and the combination of long and short anchorages at critical positions, we can enhance the integrity of the surrounding rock, effectively absorb the energy released by the surrounding rock deformation, and reduce the incidence of rockburst disasters.