Optimization of cut‐hole layout under high in situ stress based on numerical simulation and field tests

Abstract A well‐designed cut‐hole layout is crucial for improving drilling and blasting efficiency in deep underground engineering. For this purpose, this study investigates the patterns of blast‐induced rock damage under various cut‐hole layouts and ground stress conditions through numerical simulations and field tests. The key cut‐hole parameters include uncoupling coefficients ( K ), the empty hole diameter (), and hole spacing (). In simulations, when K exceeded 1.15, indicating the use of uncoupling charge, both the rock damage scope and the blast shock wave transmission were significantly suppressed. In contrast, the coupled charge ( K = 1.0) demonstrated better performance in promoting damage. Additionally, large‐diameter empty holes ( = 8 or 10 cm) showed pronounced free surface effects on the facing‐blasting side, completely breaking the rock mass between the charge hole and the empty holes and effectively guiding crack propagation on the back‐blasting side. Hole spacing had an inhibitory effect on effective plastic strain near empty holes; the optimal value is 14 cm. Finally, field tests were conducted, and the results revealed that the suggested cut‐hole parameters enhanced cycle advancement and borehole utilization by 9.0% and 12.3%, respectively, while reducing the powder factor by 27.4%. These findings provide valuable insights for similar underground engineering applications.