In order to explore the reasonable spacing of charge holes in empty-hole directional blasting, based on the action mechanism of empty-hole directional blasting, the influence of charge hole spacing on crack propagation is studied, the calculation formula of charge hole spacing is deduced, and the blasting excavation process in Shijiazhuang South Ring Expressway Tunnel is simulated by finite element software. The results show that by setting empty holes on both sides of the charge holes in the peripheral blasting, the guiding cracks can be formed in the connecting direction between the empty hole and the charge hole, the propagation of cracks in other directions can be suppressed, and the spacing of charge holes can be enlarged. Reasonable charge hole spacing is very important to realize the effect of empty-hole directional blasting; the spacing is small, the rock will be overbroken, and the utilization ratio of explosives is reduced; large spacing, the guiding effect of empty holes is weak, and the effective directional cracks cannot be formed. The spacing between charge holes is closely related to the mechanical properties of rock, detonation parameters of explosive, and aperture of the charge hole and empty hole. According to the simulation results of crack propagation in different spacing, the blasting performance is the best when the charge hole spacing is 800–1000 mm, which is completely consistent with the theoretical calculation result of charge hole spacing 948 mm.

中文翻译：

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空孔定向爆破作用下装药孔距对裂纹扩展行为的影响

为了探讨空孔定向爆破中药孔的合理间距，基于空孔定向爆破的作用机理，研究了药孔间距对裂纹扩展的影响，推导了药孔间距的计算公式。用有限元软件模拟了石家庄南环高速公路隧道的爆破开挖过程。结果表明，通过在周边爆破中在装药孔的两侧设置空孔，可以在空孔与装药孔之间的连接方向上形成导向裂纹，可以抑制裂纹向其他方向的传播，充电孔的间距可以扩大。合理的药孔间距对实现空孔定向爆破效果非常重要。间距小，岩石易碎，炸药利用率降低。间距大，空孔的导向作用弱，不能形成有效的定向裂纹。装药孔之间的间距与岩石的机械性能，炸药的爆炸参数以及装药孔和空孔的孔径密切相关。根据在不同间距下裂纹扩展的模拟结果，在药孔间距为800–1000 mm时，爆破性能最佳，这与948 mm药孔间距的理论计算结果完全一致。装药孔之间的间距与岩石的机械性能，炸药的爆炸参数以及装药孔和空孔的孔径密切相关。根据在不同间距下裂纹扩展的模拟结果，在药孔间距为800–1000 mm时，爆破性能最佳，这与948 mm药孔间距的理论计算结果完全一致。装药孔之间的间距与岩石的机械性能，炸药的爆炸参数以及装药孔和空孔的孔径密切相关。根据在不同间距下裂纹扩展的模拟结果，在药孔间距为800–1000 mm时，爆破性能最佳，这与948 mm药孔间距的理论计算结果完全一致。