双空孔间距对爆破槽腔断面大小的影响

为了探究空孔间距对巷道掘进掏槽爆破效果的影响，基于大红山铜矿某巷道建立有限元数值模型，计算双大直径空孔不同布孔间距条件下的掏槽爆破成腔断面积，并对最优方案开展现场验证。研究结果表明:空孔间距d_v=15 cm时，槽腔断面积为0.1641 m2；当d_v增加到d_v=25 cm时，槽腔断面积为0.2116 m2，断面积增大28.94%；当 d_v增加到35 cm时，槽腔断面面积为0.2436 m2，断面积增大15.1%；但当d_v增大到45 cm时，槽腔面积为0.1740 m2，断面积减小17.8%；当d_v增大到55 cm时，槽腔面积为0.0951 m2，断面积减小45.3%。对成腔断面积最大的空孔间距d_v=35 cm的布孔方案进行现场试验，2号现场试验测得槽腔断面宽度、高度及断面积分别比模拟结果小4.0%、3.4%和4.98%，多次试验与模拟结果误差均在5%以内，能够为地下巷道掏槽爆破成腔体积预测的数值方法构建提供数据参考。

Influence of double empty hole spacing on section size of blasting chamber

In order to explore the influence of double empty hole spacing on the tunnel excavation blasting effect, the range of empty hole spacing is calculated according to the compensation space theory and the theoretical formula of hole deviation. A finite element numerical model of a roadway of Dahongshan Copper Mine is established based on the HJC constitutive model of concrete and multi-material ALE algorithm of LS-DYNA. By adding the *MAT_ADD_EROSION keyword, the damaged rock elements are observed, and the cross-section area of the cavity for cut blasting with large-diameter double empty holes of different spacing is calculated. The results show that when the hole spacing d_v is 15, 25, 35, 45 and 55 cm, the cavity section area is 0.1641, 0.2116, 0.2436, 0.1740 and 0.0951 m2, respectively. When the hole spacing increased by 10 cm each from 15 cm to 55 cm, the cavity section area increased by 18.94% and 15.1% and decreased by 17.8% and 45.3%, respectively. Thus, with the increase of empty hole spacing, the section area increases first and then decreases. When d_v = 35 cm, it reaches its maximum. This case was tested in the field. The width, height, and area of the cavity section measured by the No. 2 field test are 4.0%, 3.4%, and 4.98%, respectively, smaller than the simulation results. The error between multiple tests and simulation results is within 5%, indicating that the test results are in good agreement with the simulation results, which can provide data reference for the construction of a numerical method for predicting the cavity volume of underground tunnel cutting blasting.