多孔同段聚能爆破煤层增透数值模拟及应用
Numerical simulation of multi-hole and same delay time of cumulative blasting in coal seam and its application
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摘要: 构建三维多孔同段 (多个炮孔同时起爆) 聚能爆破模型, 利用ANSYS/LS-DYNA软件再现聚能射流及爆炸应力波传播与叠加的过程, 探讨应力波的传播规律;同时对多孔同段聚能爆破下不同间距炮孔间的煤体单元应力进行了分析。研究结果表明, 炸药爆炸后形成聚能射流侵彻煤体, 随后形成的爆炸应力波沿着各自的方向传播, 之后相遇叠加, 相邻炮孔间距越大, 应力波叠加所需时间越长且叠加应力越小;比较不同间距相邻炮孔间煤体单元应力, 发现裂隙首先在炮孔周围产生, 随着爆轰气体的传播, 裂缝将主要沿着炮孔连线扩展。只要相邻炮孔间距得当, 相邻炮孔间煤体区域相当于受到2次爆破作用, 使得煤体裂隙充分发育并相互贯通, 提高瓦斯抽采率。同时在平顶山开展了煤层多孔聚能爆破现场实验, 结果表明多孔聚能爆破能有效提高煤体致裂程度, 同时确定了多孔聚能爆破最佳相邻炮孔间距。Abstract: A model of multi-hole cumulative blasting was established by using ANSYS/LS-DYNA to study the mechanism of crack propagation and permeability increasing under the multi-hole cumulative blasting in coal seam.The model represented all of the explosion process, including the formation of shaped jet, the propagation and superposition of explosive stress waves.The variation of coal element stress with time under different holes spacing was analyzed.It was found that cumulative jet penetrated into coal seam after the explosive exploded.The explosion stress waves propagated along their respective directions and the explosion stress waves superposed finally.It was also found that the longer the distance between adjacent holes, the longer it took for the stress wave to superimpose.Comparison of unit stress of coal under different holes spacing, it was found that cracks first appeared around the hole, the cracks then spread mainly along the holes line.As long as the distance between adjacent blast holes is proper, the coal between the holes is equivalent to twice blasting effect.The cracks of coal were fully developed and interconnected with each other, and then it would increase gas extraction rate.Besides, the multi-hole cumulative blasting tests were carried out and the test results show that multi-hole cumulative blasting can significantly improve the permeability of coal.At the same time, the reasonable distance of adjacent cumulative blasting hole is determined.