针对低透气性煤层掘进过程中,瓦斯抽放难度高、掘进效率低等难点问题,提出应用CO2增透预裂技术,提升煤层透气性系数与瓦斯抽放效率,提高工作面掘进效率。应用岩土力学模拟软件,模拟分析了煤层掘进过程中煤体破坏分布与应力分布状态。模拟结果表明:掘进过程中,巷道两帮破碎区域为距巷帮0~3m的范围,巷帮主要应力集中区域为距巷帮3~4m的区域,应力为18.0~18.9MPa。根据数值模拟结果,设计了煤层CO2增透的预裂孔与抽放孔的详细参数,进行了现场验证。现场试验与效果分析表明:预裂前后钻场瓦斯抽采瓦斯纯流量提高了27%,瓦斯抽放浓度提高了1.7倍,可解吸瓦斯量由7.27降到4.30m3/t,掘进效率明显提高。
Aiming at the highly difficult gas drainage and low efficient drivaging of low permeability coal seam drivaging process of a coal mine, CO2 anti-reflection pre-splitting technology was put forward to improve seam permeability coefficient, gas drainage efficiency and working face drivaging efficiency. Rock mechanics simulation software was applied to simulate and analyze the coal damage distribution and stress distribution state in coal seam drivaging process. The simulation results showed that, the broken area on both sides of the roadway is 0~3m from one side, and the main stress concentrated area of roadway sides is 3~4m from roadway sides, the stress intensity ranges from 18 to 18.9 MPa in the drivaging process. Meanwhile, according to the simulated conclusions, detail parameters of pre-splitting and drainage drill holes were designed specifically. Field tests and effect analysis showed that, the net flow of gas drainage is increased by 27%, drainage concentration by 1.7 times, and desorption gas quantity is reduced from 7.27 m3/t to 4.3 m3/t in each dill site after pre-splitting, significantly improving the drivaging efficiency.
