Impacts of delayed detonation of empty hole bottom charge on the cavity forming effects of deep hole parallel cutting
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摘要: 针对深孔钻爆掘进中直眼掏槽成腔效率低下的难题，提出空孔底部装药延迟起爆的解决方案。首先通过理论分析、模型试验及数值模拟，研究了空孔底部装药延迟起爆对成腔效率的影响；然后结合岩石抛掷过程的高速影像与数值模拟，揭示了两种炮孔装药爆破协同作用下的成腔机制；最后开展现场试验验证其实际应用效果。结果表明：空孔底部装药延迟起爆可以大幅消除槽腔底部的残留根底，使得成腔效率从80 %以下提升到95 %以上；在掏槽孔爆破阶段，围岩夹制作用导致槽腔残留根底，但新生的临空面有利于后续阶段根底的抛掷；在空孔底部装药爆破时，由于围岩夹制作用减弱，根底抛掷速度较上部岩体高约2.0 m·s−1，可以实现根底的有效抛除与良好的成腔效果。与传统直眼掏槽技术相比，采用空孔底部装药延迟起爆方法，循环进尺提高了0.35 m，炸药单耗降低了0.43 kg·m−3，证实了改进后的直眼掏槽技术有助于提升掘进效率和降低掘进成本。研究成果可以为地下工程深孔掏槽爆破优化提供理论支撑与实践参考。
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关键词:
Abstract: The speed of underground blasting driving is primarily determined by the effectiveness of cutting blasting. To address the low cavity forming efficiency of parallel cutting in deep hole blasting driving, a solution involving delayed detonation of the bottom charge in the empty hole was proposed. Firstly, theoretical analysis, model experiments, and numerical simulations were conducted to investigate the influences of delayed detonation of empty hole bottom charge on the cavity forming efficiency. Subsequently, combined with high speed photography and numerical simulations of rock throwing process, the cavity forming mechanism under the synergistic effect of charge blasting in two types of blasting holes was revealed. Finally, field tests were performed to verify its actual application effects. The results indicate that delayed detonation of the empty hole bottom charge could significantly eliminate residual stumps at the bottom of the cutting cavity, increasing the cavity forming efficiency from less than 80 % to over 95 %. During the blasting stage of cutting holes, the strong clamping effect of surrounding rock leads to residual stumps in the cavity, but the newly formed free face could facilitate the throw of stumps subsequently. During the blasting stage of empty hole bottom charge, the weakened clamping effect of surrounding rock enables the residual stumps to be thrown out at the relatively high velocity, thereby achieving an excellent cavity forming effect. The rock throwing velocity during the empty hole blasting is about 2.0 m·s⁻1 higher than that during cutting hole blasting. Compared with the traditional parallel cutting technique, the proposed method increases the cycle footage by 0.35 m and reduces the specific charge by 0.43 kg·m⁻³. This confirms that the improved parallel cutting technique is conducive to enhancing driving efficiency and reducing driving costs. The research findings could provide theoretical supports and practical references for the optimization of deep hole cutting blasting in underground engineering. -
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