近年来，我国陕北大部分浅埋煤层矿井在开采过程中，因地质条件、通风方式、采煤工艺等因素影响，致使工作面回风隅角出现氧气浓度低于18%的低氧现象频发，已成为矿井安全生产过程中面临的新难题。本文以张家峁煤矿15211工作面为研究对象，围绕工作面回风隅角低氧形成机制及防治方案进行系统研究，具体研究内容与结果如下：

通过理论分析、现场实测调研发现，工作面所采煤层瓦斯赋存分带处于二氧化碳-氮气带（CO₂-N₂）。工作面低氧现象主要发生在回风隅角区域，通过对比工作面检修、生产及低氧时间段回风隅角氧气浓度变化规律发现，工作面回风隅角低氧现象产生主要因采空区气体大量异常涌出所致，而地表大气压降低导致的采空区内外压差，是推动采空区内部低氧浓度气体涌出的直接原因。

通过现场监测与遗煤耗氧实验得出，采空区遗煤主要通过物理吸附与化学反应双重作用消耗氧气，从而产生大量的低氧浓度气体。而工作面采空区因开采扰动的影响，造成采空区与附近老空区之间气体相互贯通，使得上覆及临近采空区内气体向工作面采空区扩散，是影响工作面回风隅角产生低氧现象的主要原因之一。经过地表裂隙漏风测定试验发现，因地表漏风的影响使得地表气体涌入工作面的速率在0.09~0.13m/s之间。

基于数值模拟计算得出，当无其他因素影响时，在正常配风量2000m³/min下，工作面各用风地点氧气浓度均处于18%以上；当地表裂隙存在向采空区漏风时，随着漏风速率从0.09m/s增加到0.13m/s过程中回风隅角低氧现象愈加严重；在地表裂隙漏风因素影响下，当工作面配风量增大时，回风隅角低氧现象严重程度有所减缓。

最后依据工作面回风隅角低氧形成机制，针对性的提出了工作面回风隅角低氧预测与预防技术方案，并基于数值模拟研究所得结果，建立了一种以风流引射器与均压通风为主，以其他防治技术为辅的低氧处置技术方案。通过现场实际应用，发现回风隅角氧气浓度与其他气体浓度均处于正常范围之内，且回风隅角最高氧气浓度升至19.2%。

In recent years, in the mining process of most shallow coal seam mines in Northern Shaanxi, due to the influence of geological conditions, ventilation mode, mining technology and other factors, low oxygen phenomenon with oxygen concentration less than 18% occurs frequently in the return air corner of the workface, which has become a new problem in the process of mine safety production. Taking 15211 workface of zhangjiamao coal mine as the research object, this paper systematically studies the formation mechanism and prevention scheme of low oxygen in the return air corner of the workface. The specific research contents and results are as follows:

Through theoretical analysis and field survey, it is found that the gas occurrence zone of the coal seam mined in the workface is in the carbon dioxide nitrogen zone (CO₂-N₂). The low oxygen phenomenon in the workface mainly occurs in the return air corner area. By comparing the change law of oxygen concentration in the return air corner during the maintenance, production and low oxygen time of the workface, it is found that the low oxygen phenomenon in the return air corner of the workface is mainly caused by a large number of abnormal gas gushing out of the goaf, and the pressure difference inside and outside the goaf caused by the reduction of surface atmospheric pressure is the direct cause of promoting the low oxygen concentration gas gushing out of the goaf.

Through on-site monitoring and oxygen consumption experiment of residual coal, it is concluded that the residual coal in goaf mainly consumes oxygen through the dual action of physical adsorption and chemical reaction, resulting in a large amount of low oxygen concentration gas. Due to the influence of mining disturbance in the goaf of the workface, the gas between the goaf and the nearby old goaf is connected with each other, so that the gas in the overlying and adjacent goaf diffuses to the goaf of the workface, which is one of the main reasons affecting the low oxygen phenomenon in the return air corner of the workface. Through the measurement test of surface fissure air leakage, it is found that the rate of surface gas flowing into the workface is between 0.09 ~ 0.13m/s due to the influence of surface air leakage.

Based on the numerical simulation calculation, when there are no other factors, under the normal air distribution volume of 2000 m³/min, the oxygen concentration at each air consumption location of the workface is more than 18%; When there is air leakage from surface cracks to goaf, the phenomenon of low oxygen in return air corner becomes more and more serious as the air leakage rate increases from 0.09 m/s to 0.13 m/s; Under the influence of surface crack air leakage, when the air distribution volume of the workface increases, the severity of low oxygen in the return air corner slows down.

Finally, according to the formation mechanism of low oxygen in the return air corner of the workface, the technical scheme of low oxygen prediction and prevention in the return air corner of the workface is put forward. Based on the results of numerical simulation, a low oxygen treatment technical scheme based on air flow ejector and pressure equalizing ventilation and supplemented by other prevention and control technologies is established. Through field application, it is found that the oxygen concentration and other gas concentrations in the return air corner are within the normal range, and the maximum oxygen concentration in the return air corner rises to 19.2%.

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