低透气煤层双孔预裂爆破增透有效影响范围研究

Study on Effective Influence Range of Permeability Enhancement by Double Hole Presplitting Blasting in Low Permeability Coal Seam

煤层深孔预裂爆破增透技术能够显著提高低透气性煤层瓦斯的抽采效率。研究双孔不同间距、不同装药结构爆破增透对煤体破坏范围的影响对提高瓦斯抽采率具有重要意义。以新安煤矿二1煤层为研究对象,采用数值模拟的研究方法研究了双孔连续爆破应力波的传播过程及对煤层影响的范围。研究结果表明:煤体双孔连续爆破模型,不耦合装药粉碎圈半径小于耦合装药,裂隙圈半径大于耦合装药,有利于爆破应力波传播及裂纹扩展,裂纹密度均匀;采用耦合装药结构和不耦合结构,分别对炮孔间距为4m、6m和8m的两孔连续起爆模拟结果和现场验证比较,确定新安煤矿二1煤层预裂爆破两爆破孔的合理间距为6m,不耦合装药系数1.25。

The permeability enhancement technology of deep-hole pre-splitting blasting can significantly improve the extraction efficiency of gas in low-permeability coal seam.It is of great significance to study the influence of permeability enhancement by double-hole blasting with different spacings and charging structures on the damage range of coal body to improve gas drainage rate.Taking the No.2-1 coal seam of Xin'an Coal mine as the research object,the propagation process of stress wave and its influence on the coal seam from double-hole continuous blasting were studied by numerical simulation.The results show that:In the two-hole continuous blasting model of coal body,the radius of crushing circle of uncoupled explosive charging structure is smaller than that of coupled explosive-charging structure,and the radius of fracture circle is larger than that of coupled explosive charging structure,which is beneficial to the propagation of blasting stress wave and crack propagation,and the crack density is uniform.By using coupled explosive charging structure and uncoupled explosive charging structure,the simulation results of continuous detonation of two holes with spacings of 4 m,6 m and 8 m were compared with on-site verification.It was determined that the reasonable spacing between two blasting holes in the presplit blasting of the No.2-1 coal seam of Xin'an Coal mine was 6m with a decoupling coefficient of 1.25.