浅埋近距离煤层群工作面上隅角贫氧致因及综防技术

我国神东、平朔、大同煤田赋存着大量浅埋近距离煤层群,浅埋近距离煤层群具有煤层埋藏浅、煤层间距近等特点,在开采扰动下,层间易产生裂隙形成漏风通道,当地表空气进入上覆采空区,易引起上覆采空区遗煤自燃,间接影响下层煤开采过程中工作面上隅角的氧气浓度,造成贫氧现象。为了探究浅埋近距离煤层群工作面上隅角贫氧致因,提出防治贫氧的措施,以大恒煤矿91103综采工作面为研究背景,采用理论分析、CDEM数值模拟以及SF6示踪气体漏风测试等方法进行了研究。结果表明:地面裂缝、沉积现象明显;模拟煤岩损伤、破裂过程、裂隙发育,得出地表与上覆采空区、工作面贯通模型;利用连续定量释放SF6示踪气体在工作面进行漏风测定,测定结果验证了数值模拟中地表、上覆采空区以及工作面的贯通。工作面上隅角贫氧是由于浅埋赋存煤体破碎析出的低氧气体、采空区氧化衍生气体以及防灭火注入的惰性气体,在通风负压和大气压力的双重作用下,通过漏风通道进入工作面,加之U型通风方式的通风特点等多种因素共同造成的,其中工作面与地表贯通造成漏风严重是上隅角贫氧的主要致因。基于对贫氧致因的研究,大恒煤矿采用了井上下堵漏、安设风帘、埋管抽采、风机配合风筒等综合性防治措施,有效解决了工作面上隅角贫氧对安全生产的制约和影响,确保了工作面上隅角氧气浓度始终处于正常水平。

Causes of oxygen deficiency in upper corners of working face in shallow-buried and contiguous seams and comprehensive prevention technology

Shendong,Pingshuo,Datong coalfield in China have a large of shallow-buried and contiguous seams,shallow buried and con?tiguous seams have the characteristics of shallow coal seams and close seam spacing.Under mining disturbance,cracks are likely to form air leakage channels.Surface air entering the overlying gob can easily cause spontaneous combustion of the remaining coal in the overlying gob,which indirectly affects the oxygen concentration in the upper corners of the working face during the mining of the underlying coal,resulting in oxygen depletion.In order to explore the causes of oxygen deficiency in the corner of the working face and put forward the measures to prevent oxygen deficiency,taking No.91103 fully-mechanized working face of Daheng Coal Mine as the research background,theoretical analysis,CDEM numerical simulation and SF6 air leakage test methods were used for the study.The results show that there are obvious cracks and sedimentation on the ground.By simulating the process of coal and rock damage,fracture process and cracks develop?ment,the ground surface and the overlying gob and working face are connected.Using continuous quantitative release of SF6 tracer gas in the working face for air leakage measurement,the measurement results verify the numerical simulation of the surface,overlying gob and working face through model.The oxygen deficiency in upper corner is due to the low oxygen gas released from the crushing of shallow-bur?ied coal,the oxidation derived gas from gob and the inert gas injected into fire prevention.Under the dual effects of ventilation negative pressure and atmospheric pressure,low oxygen gas by the air leakage channel enters the working face as well as the ventilation characteris?tics of U-type ventilation mode,resulting in oxygen deficiency.Among them,the serious air leakage caused by the connection between the working face and the ground surface is the main cause of oxygen deficiency in the upper corner.Based on the research on the causes of poor oxygen,Daheng Coal Mine adopted comprehensive prevention and control measures,such as plugging up and down the well,instal?ling air curtains,buried pipe drainage,fans with air duct,etc.,which effectively solved the problem of poor oxygen at the upper corners of the working surface,and the oxygen concentration in the upper corner of the working face was always at the normal level.