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为解决煤矿瓦斯抽放问题,在岩层中布置水平深孔,以实行预裂爆破。以爆破动力学、岩石力学、损伤力学等作为理论基础,利用三维数值分析软件,建立煤岩复合介质模型、全煤介质爆破模型,分析深孔预裂爆破在多层介质中的力学特性。基于重庆某矿的计算结果表明,煤岩复合介质中,爆破孔与控制孔间距为1.5 m时的爆破效果与全煤介质中3.0 m孔间距基本相当。对2种模型中控制孔孔口、孔底有效应力随时间的变化进行分析可知,全煤模型孔口、孔底应力最大值分别为4.20和9.33 MPa,复合介质模型孔口、孔底分别为1.64和4.14 MPa。对比应力波相同传输距离的有效应力值可知,分界面对应力的衰减作用非常明显。经过工程验证,模拟结果与现场瓦斯抽放效果相符。
In order to solve the problem of gas drainage in coal mines, horizontal deep holes are arranged in the rock strata to carry out presplitting blasting. Based on the theory of blasting dynamics, rock mechanics and damage mechanics, the three-dimensional numerical analysis software is used to establish the coal-rock composite medium model and the whole-coal medium blasting model to analyze the mechanical properties of deep-hole presplitting blasting in multi-layered media. Based on the calculation results of a mine in Chongqing, it is shown that the blasting effect when the distance between the blasting hole and the control hole is 1.5m is basically the same as the 3.0m hole spacing in the whole coal medium in the coal-rock composite media. The analysis of the change of the effective stress at the bottom of the two models with the passage of time shows that the maximum stress at the orifice and the bottom of the hole in the whole coal model is 4.20 and 9.33 MPa respectively. The orifice and the bottom of the composite medium model are 1.64 and 4.14 MPa. Comparing the effective stress values of the same transmission distance of the stress wave, it can be seen that the attenuation effect of the interface on the stress is very obvious. After engineering verification, the simulation result is consistent with the gas drainage effect on site.