兴安矿段间无煤柱开采对采空区注氮效果的影响

Effect of Non-pillar Mining in Xing’an Coal Mine on Nitrogen Injection in Goaf

为提高兴安矿四水平11 煤层中部二段工作面段间无煤柱开采形成的大面积复合采空区的注氮效果,使用 FLAC^3D数值模拟软件开展应力分布模拟,使用 COMSOL 软件建立采空区注氮防灭火数值模拟模型,开展注氮效果数值模拟,分析煤柱宽度与应力分布的关系及不同注氮方式下采空区自燃三带分布情况。模拟结果表明:段间无煤柱开采可有效降低煤体应力,降低冲击地压危险性,但会形成大面积复合采空区,使本采空区氧化带宽度增加,老采空区形成复燃氧化带,注氮后高浓度氮气积聚区域减小,防灭火效果显著降低。对老采空区进行灌浆增阻,并增大注氮口距离和注氮量,有助于提高注氮效果,局部未完全充填区域可以配合使用钻孔压注氮气,显著提高无煤柱开采综合注氮防灭火效果。

In order to improve the effect of nitrogen injection in large composite goaf of the two-stage middle working face in the fourth level 11 floor of Xing'an Coal Mine, FLAC3D numerical simulation software was used to carry out stress distribution simulation, and COMSOL software was used to establish a numerical simulation model of nitrogen injection and fire prevention in goaf, and to carry out numerical simulation of nitrogen injection effect. The relationship between coal pillar width and stress distribution and the three zones of spontaneous combustion under different nitrogen injection modes in goaf were analyzed. The simulation results show that non-pillar mining between sections can effectively reduce the coal stress and the risk of rock burst. However, a large area of compound goaf will be formed, which will increase the width of oxidation zone in this goaf and form a reburning oxidation zone in the old goaf. After nitrogen injection, the accumulation area of high concentration nitrogen will be reduced, and the fire prevention effect will be significantly reduced. It is helpful to improve the effect of nitrogen injection by prevent grouting in the old goaf, and increasing the distance of nitrogen injection port and nitrogen injection quantity, borehole pressure injection of nitrogen can be used in the partial incomplete filling area, the fire prevention effect of comprehensive nitrogen injection of non-pillar mining is improved remarkably.