基于动态焦散线实验的护壁药包机理研究

The mechanism of wall-protecting explosion based on dynamic caustic test

为了探究护壁爆破对爆生裂纹、原生裂纹和定向裂纹的作用机理,基于数字激光动态焦散线实验和数值模拟方法开展了一系列研究.结果表明:护壁爆破能抑制护壁一侧爆生裂纹和原生裂纹扩展;护壁一侧原生裂纹尖端动态应力强度因子两次峰值约为非护壁一侧的53%和77%,护壁管对爆炸应力波和爆生气体起到了很好的削弱作用;炸药爆炸后,由起爆位置传爆至护壁管端部形成的射流,作用炮孔壁形成初始损伤;随后沿炮孔壁向上传播的射流持续冲击护壁管端部岩体,形成"射流效应",驱动初始损伤扩展,最终形成定向裂纹.护壁爆破不仅可以保护围岩还可以产生定向断裂效果,在工程实践中应用前景广阔.

In order to explore the mechanism of wall-protecting explosion on blast-induced cracks, primary cracks and directional cracks, a series of studies based on digital laser dynamic caustic experiments and numerical simulations were conducted. The results show that wall-protecting explosion can suppress blast-induced and primary cracks propagation on the side of the retaining wall. Dynamic stress intensity factors of primary cracks on the side of the retaining wall are 53% and 77% of those on the side of non-retaining wall, and the wall-protecting pipe plays a significant role in weakening the loading of blasting stress waves and gas. After explosion, the jet formed at the end of the wall-protecting pipe from detonation position acts on the borehole wall and causes initial damage. Subsequently, the jet continues to impact the rock mass near the end of the wall-protecting pipe and forms "jet effect", which promotes the damage of primary cracks and eventually produces directional cracks. The wall-protecting explosion can protect the surrounding rock and produce directional fracturing effects, which has a wide application prospect in engineering practice.