Optimization of axial shaped charge liner configuration and its application in tunnel smooth blasting

To achieve precise control over tunnel blasting effects, this study optimized the structural parameters of a novel energy-gathering liner through numerical simulation and field tests. It also explored the optimal stand-off distance for the energy-gathering liner under surrounding rock constraints and conducted field validation. The findings can be summarized as follows: 1) When the cone angle of the energy-gathering liner is 90°, the material is aluminum alloy, and a conical explosive charge liner is used, an ideal jet shape and velocity are formed. This parameter combination provides a useful reference for industrial manufacturing of energy-gathering liners; 2) Under the simulated conditions of this study, analysis of the jet tip pressure and explosive reactivity revealed that when the spacing between explosives ranged from 10 to 90 cm, the state of the secondary charge transitioned from direct detonation to detonation following penetration over a certain distance as the spacing increased, with the penetration depth also increasing accordingly. When the spacing reached 90 cm, the jet was unable to detonate the secondary explosive; 3) Based on the numerical simulation results, four field blasting tests were conducted at the actual tunnel, with explosive charge spacings of 50 cm, 60 cm, 70 cm, and 80 cm. The results demonstrated that when the explosive charge spacing was between 60 cm and 70 cm, the best control over overbreak and underbreak was achieved. This spacing not only met the construction design requirements but also produced an optimal Smooth blasting effect.