Optimization of direct-hole cutting blasting technology for deep-buried layered surrounding rock diversion tunnels

Abstract

Objective In recent years, the trend of tunnel blasting construction extending to depth is becoming more and more significant, and the influence of layered rock mass in deep buried diversion tunnel on cutting quality in blasting construction is the key to blasting construction. Methods In order to study the influence of the location of blasting in deep layered surrounding rock on the cut blasting, a three-dimensional finite element numerical calculation model was established by using ANSYS/LS-DYNA, based on the blasting excavation project of the diversion tunnel of San Gabán hydropower station in Peru. The damage area caused by cut blasting was analyzed, and the optimization scheme was put forward for field test. Results The results show that the boundary area of layered surrounding rock has a certain influence on the range of rock damage caused by cutting blasting. The closer to the boundary area of layered surrounding rock, the smaller the range of rock damage. In order to increase the damage area of cut blasting, the location of blasting should keep a certain distance from the boundary area of layered surrounding rock. Conclusion The optimized blasting scheme was tested on site and good blasting effect was achieved. In this study, numerical simulation was used to optimize the position of the cutting hole accroding to the law of rock damage evolution, which can improve the economy and safety of tunnel construction.

Keywords

• blasting damage
• diversion tunnel
• cutting blasting
• numerical simulation
• layed surrounding rock