火成岩侵入易自燃煤层超长俯采工作面采空区自燃“三带”分布范围研究

Study on the distribution of “three zones” of spontaneous combustion in goaf of ultra-long downward working face with igneous rock intruding into coal seam prone to spontaneous combustion

大兴煤矿北一202工作面采用超长开切眼布置,存在采空区空间大、开采易自燃煤层、工作面全程俯采且顶板存在复合煤岩层采空区遗煤量大等因素,导致工作面防灭火工作难度大幅提高。通过在工作面进、回风巷道,以及上、下隅角向工作面70 m处架后采空区预埋4个束管测点,对北一202超长俯采工作面采空区自燃“三带”分布范围进行多点位观测,得出超长俯采工作面采空区最大氧化带宽度为37.7 m,位于上隅角向工作面70 m架后采空区。根据北一202工作面实际参数,建立三维几何模型,通过Fluent数值模拟分析,揭示了超长俯采工作面采空区流场及O_(2)体积分数变化规律,并将采空区自燃“三带”分布范围模拟结果与实测结果进行对比,发现两者基本一致,证明了采用数值模拟方法分析研究超长俯采工作面采空区流场、O_(2)体积分数分布规律的有效性和科学性。

The North1202 working face of Daxing Coal Mine adopts ultra-long open-off cut arrangement,and there are many factors such as large goaf space,mining of coal seam prone to spontaneous combustion,the whole process downward mining of working face,and large amount of residual coal in goaf of compound coal strata in roof,which greatly increase the difficulty of fire prevention and extinguishing of working face.Through four bundle pipe measuring points embedded in goaf behind the frame at the air inlet and return airway of the working face and 70 m from the upper and lower corners to the working face,the distribution of“three zones”of spontaneous combustion in goaf of North1202 ultra-long downward working face were observed at multiple-points,it was concluded that the maximum width of oxidation zone in goaf of ultra-long downward working face was 37.7 m,which is located in goaf behind the frame 70 m from the upper corner to the working face.In addition,according to the actual parameters of North1202 working face,a 3D geometric model was established.Through Fluent simulation analysis,the variation law of goaf flow field and O_(2) volume fraction in ultra-long downward mining face was revealed.The simulation results of“three zones”of spontaneous combustion in goaf were compared with the measured results,and it was concluded that the two results were basically consistent.It is proved that the numerical simulation method is effective and scientific to analyze the distribution law of flow field in goaf and O_(2) volume fraction in ultra-long downward working face.