Numerical simulation study on parameter optimization of smooth blasting based on damage

Aiming at the problems of surrounding rock damage and overbreak caused by excavation blasting of large section roadway, it is necessary to optimize the smooth blasting parameters. LS-DYNA software is used to establish a blasting model, and the effects of charge structure, hole spacing and smooth blasting layer thickness on damage changes are studied, and the field parameters are optimized. The results show that damage change between the two holes in the charge part of the blasthole. After detonation, fracturing damage occurs around the blasthole, as the shock wave expansion intensity gradually decreases, it turns into a stress wave, and the ore rock does not produce damage at this time. With the superposition effect of stress waves between the blasthole holes, damage occurs at the center line and extends to both sides, and damage change of air-spaced charge, as the stress wave propagates to the center of the air interval, the damage gradually develops to the center, the damage thickness gradually decreases, and meets at the center and promotes the expansion of the damage. The air space is beneficial to the propagation of stress wave and promotes the development of damage. The original rock damage in the air spacing area is mainly caused by the interaction between the stress wave superposition of adjacent blastholes and the stress wave caused by explosives on both sides of the air spacing area of the middle blasthole. The increase of air interval length and hole spacing will reduce the damage degree and thickness of rock in air spacing area. According to the combination of theoretical calculation and numerical simulation, it can be concluded that the interval distance is 500 mm, the hole spacing is 600 mm, and the thickness of the smooth blasting layer is 700 mm. Through the on-site experiments, the smooth blasting effect is improved, reducing the increase in support costs caused by over excavation and underexcavation, and achieving good results.