深井扇形组合孔短延时爆破裂纹扩展模拟研究

提出了一种扇形组合孔短延时爆破的构想，即在常规的每排扇形崩落孔中间增加一排致裂孔，崩落孔与致裂孔之间短延时间隔起爆。使用ANSYS/LS-DYNA对不同延时时间及不同围压加载条件下的爆破方案进行数值模拟研究，发现高应力环境下常规扇形孔爆破无法形成有效爆破漏斗，扇形组合孔短延时爆破则损伤破裂更加有效、破岩效果更好。此外对不同围压条件下的裂纹扩展进行分析，爆破裂纹扩展趋向于最大主应力方向。数值模拟及现场工程实践证实，当最大主应力方向与扇形崩落排孔成一定小角度，即平行崩落排孔方向加载较大围压、垂直排孔方向加载较小围压时，扇形组合孔短延时爆破不仅可以改善岩石破碎效果，也可以有效保护后排炮孔和保留岩体。

Simulation of Crack Propagation Induced by Short Delay Blasting with Blastholes in a Combined Fan Pattern for Deep Well

A concept of short delay blasting with blastholes in a combined fan pattern was put forward, in which a row of reinforced holes were added between each row of conventional fan-pattern holes, and detonation was initiated with short delay interval between the conventional row of holes and the added row of holes. The blasting scheme with different delay interval, and blastholes loaded with different confining pressure were numerically simulated with ANSYS/LS-DYNA. It is found that blasting crater cannot be effectively produced by adopting the scheme with conventional holes in fan pattern under high geo-stress environment, while the scheme of short delay blasting with holes in combined fan pattern is more effective in obtaining damaged and ruptured rock, showing better rock breakage effect. In addition, analysis of crack propagation under different confining pressure shows that the blasting crack tends to grow in the direction of the maximum principal stress. The numerical simulation and field engineering practice have proven that when there is an acute angle between the maximum principal stress and that added row of blastholes in fan pattern, that is, higher confining pressure is loaded in the direction of the horizontal row of holes, and lower confining pressure is loaded in the direction of the vertical row of holes, the short-delay blasting with blastholes in such a combined fan pattern can not only improve the rock breakage effect, but also effectively keep rear row of blastholes and the rock mass behind not impacted by the blasting.