岩石深孔爆破对邻近煤层的动应力作用

为解决松软煤体爆破孔成形困难导致深孔预裂爆破技术无法应用的问题,选择在运输巷底板距煤 层较近的岩石中进行爆破,利用数值模拟方法进行了相关理论探讨。分析了煤岩介质和单煤体介质中布孔的 差异,建立了单煤体和煤岩体深孔预裂爆破的5个数值计算模型。研究了单煤体和煤岩介质爆破孔与抽放孔 连心线上有效应力随距离的变化,从岩孔爆破传播到煤层其应力衰减的程度较单煤层中大得多,但在靠近抽 放孔附近煤层,二者的差距变小。抽放孔轴线方向所受有效应力的大小是决定爆破效果的重要因素,煤岩介 质中爆破孔与抽放孔间距为2.0m 时,抽放孔轴线方向上的平均有效应力与单煤层中爆破孔与抽放孔间距 为3.0m 时的相当,可作为实现岩孔爆破效果的布孔参数。

Dynamic stress in adjacent coal seams induced by deep-hole blasting in rock

To overcome the difficulty in using the deep-hole pre-splitting blasting technology in the soft coal seams prone to resulting in the borehole collapse,a new method was applied to increasing the gas drainage rate,in which the rock nearby the coal seam was exploded at the bottom of the laneway.The theories for the technique were explored by numerical simulation.Layouts of blast holes and drain holes were compared the single coal seam and the coal-rock media.Five numerical computational models were constructed by DYNA3D,including a single coal model and four coal-rock models with the different distance between the blast hole and the drain hole.The corresponding effective stress was computed along the linking line of the blast hole and the drain hole.The computational results show that the attenuation of the effective stress from the blast hole to the drain hole is more in the coal-rock media than in the single coal,whereas the effective stress difference between the two media decreases in the coal seams adjacent to the drain holes.The distribution of the effective stress along the axis of the drain hole is significant to the drain effect.The mean effective stress along the axis of the drain hole in coal-rock media,when the distance between the blast hole and the drain hole is 2.0 m,is appropriately the same as that in the single coal seam,when the distance between the blast hole and the drain hole is 3.0 m.And it can be used as the layout parameter to keep the same blast effect in the coal-rock media as in the single coal seam.