Influence of Crustal Stress on Explosion Crack Propagation Behavior and Application in Shallow and Deep Buried Tunnel Engineering

Abstract

Rational utilization of the guiding effect of crustal stress on explosive crack can significantly enhance blasting efficiency. This paper modified the calculation models for the crushed zone and fractured zone in tunnels at different burial depths and validated the models using numerical simulation methods. The influencing factors of blasting crack extension in deep and shallow buried roadways were analyzed, and the guiding significance of crack extension characteristics on the design of blasthole mesh parameters was discussed. The results show that the error in the theoretical calculations is controlled within 6%, indicating a high degree of accuracy. The longest radial main cracks appeared in the directions of 75°–90°, 70°–72°, and 74° in the blast holes for burial depths H ≤ h_q, h_q < H ≤ H_P, and H > H_P, respectively. Blasting yields optimal results when the blasthole alignment follows the direction of main fracture propagation.