三维模型柱状药包爆生裂纹扩展规律研究

利用有机玻璃材料,采用高速摄影和数值模拟方法研究不同位置起爆柱状药包爆生裂纹扩展和损伤破坏差异。研究结果表明,正反向起爆时炮孔周围均产生多条径向裂纹,爆生裂纹面经历了由"密集波纹状→光滑平坦→少量径向微裂隙→密集径向裂隙"逐步转变的过程。正向起爆时,径向裂纹优先产生,并逐渐向模型内部延伸,在炮孔底部产生较大的超深扩展现象。而反向起爆时,底部"圆锥形"裂纹面与炮孔径向裂纹同时产生,炮孔底部裂纹面消耗较多能量,其径向裂纹扩展速度较正向起爆时小,扩展时间也较短,但有利于岩石的抛掷。由模拟结果可知,柱状药包反向起爆比正向起爆爆破损伤区范围大,并且爆破损伤的均匀程度好。因此,在掏槽爆破中,为提高岩石的抛掷效果,应尽量采用反向起爆方式进行爆破;而在松动爆破中,为增加岩石中裂纹的扩展深度,应尽量采用正向起爆方式进行爆破。

Study on crack propagation law of column charges in three-dimensional models

High-speed photography and numerical simulation were used to study the difference of crack propagation and damage of cylindrical charge when arranged at different positions in polymethyl methacrylate(PMMA). The results show that there are multiple radial cracks around the boreholes during forward and reverse detonation, and the explosive crack surface undergoes a gradual transformation from "dense corrugated" to "smooth flat" to "a small amount of radial microcracks" to "dense radial cracks". In the forward detonation, the radial crack occurs preferentially and gradually extends to the interior of the model, resulting in a large ultra-deep propagation at the bottom of the borehole. In reverse detonation, the bottom "conical" crack surface and the borehole radial crack occur at the same time, the crack surface at the bottom of the borehole consumes more energy, the radial crack propagation speed is smaller and the propagation time is shorter than that in the forward detonation, but it is beneficial to the throwing of rock. The simulation results show that the damage area of cylindrical charge reverse detonation is larger than that of forward detonation blasting, and the uniform degree of blasting damage is better. Therefore, in groove blasting, in order to improve the throwing effect of the rock, the reverse detonation method should be adopted as long as possible.While in the loose blasting, in order to increase the crack propagation depth in the rock, the forward detonation method should be adopted as long as possible.