岩石介质中双孔爆破效应的数值模拟研究

Numerical Simulation of Explosion Effects of Double-hole Blasting in Rock Medium

基于动力分析软件LS-DYNA及Langrange-Euler耦合算法,数值模拟研究了双炮孔同时起爆和微差起爆(微差时间分别为0.05 ms、0.1 ms、0.3 ms和5 ms)时爆炸冲击波在岩石介质中的传播规律和爆破对炮孔周围岩体振动效应的影响。研究表明:双炮孔同时起爆初期,损伤破碎区的扩展类似于单孔爆破;当爆炸冲击波相互叠加后,两炮孔中间纵向单元和药柱内外两侧横向近区单元的压力和等效应力随爆心距的增大而减小,而自由面上单元呈现出先增后减的变化趋势,且在距药柱10 cm外出现内侧单元的压力和应力值均高于外侧;微差起爆可缓解爆破振动和改善爆破效果,以同时起爆药柱完全引爆所需时间0.3 ms为例,当微差小于0.3 ms时,随着微差时间的延长,微差起爆对周围岩体单元的压力和等效应力峰值的降低幅度越大,同时缓解岩体纵向爆破隆起和z方向的振动效应也越明显,但超过0.3 ms后则微差起爆的改善效果受到一定限制。

Based on the dynamic analysis software of LS-DYNA and Langrange-Euler coupling algorithm, the propagation rules of shock wave of explosion and blasting effects of rock medium vibration are studied by numerical simulation with the simultaneous initiation and micro-delay initiation （different millisecond time intervals ：0.05 ms, 0.1 ms,0.3 ms and 5 ms） in rock mass. The results show that the expansion of damage zone in the rock medium at the beginning of simultaneous initiation is similar to that of single-hole blasting. When explosion shock waves super- impose with each other,the pressures and equivalent stresses of the longitudinal unit in middle of the two-hole and the near-field element on both sides of charge column decrease with increasing of the distance from explosion center. Meanwhile, the trend of pressure and equivalent stress variations in the unit of free surface increases firstly and then decreases, and the pressures and stresses of the inside unit beyond 10 cm range on both sides of medicine column are higher than that of the outside. The millisecond delay initiation can relieve blasting vibration and improve blasting effect. When the millisecond time interval is less than about O. 3 ms ,the decreased amplitude of peak pressure and e- quivalent stresses are enlarged with the millisecond time interval increase. The bulge effect of longitudinal rock mass and vibration effect in the z direction is also more obvious, and the improvement effect of millisecond initiation is limited when the millisecond time interval is more than 0.3 ms.