呼吸效应对矿井封闭火区氧浓度的影响分析

为避免因火区封闭导致重大安全事故发生，通过采集某矿井1 d内3个不同监测点的大气压力变化情况，建立大气压力波动模型并分析计算，同时建立火区内外压差100，750 Pa情形下的氧浓度模型进而获得火区内侧氧气浓度因呼吸效应，在不同压差、体积大小火区、风阻、瓦斯涌出量、封闭时刻等多因素耦合影响下随时间的变化规律，以评估火区危险性。研究结果表明:井下大气随地面大气周期波动，封闭火区内、外侧之间的气压差因外界大气波动呈现16 h的余弦波动和8 h的线性波动周期变化；密闭质量好的火区具有更好地抗干扰性，内侧氧浓度的降低主要依靠瓦斯稀释；密闭质量差的火区，内侧氧浓度易受到火区涌出瓦斯、外界涌入大气双重影响；火区氧浓度在2%~12%之间波动，以至火区存在发生瓦斯爆炸的可能性；火区内外压差较大时，氧浓度波动变化幅度更大，危险作用持续时间更长。结合火区氧浓度波动模型，可有效地对矿井火区采取安全的防范措施，避免瓦斯爆炸事故发生。

Analysis on influence of respiratory effect on oxygen concentration in closed fire zone of mine

In order to avoid the major safety accident caused by the closed fire zone,a model of atmospheric pressure fluctuation was established and analyzed through collecting the change of atmospheric pressures at three different monitoring points in a mine within one day.Meanwhile,a model of oxygen concentration under the pressure difference of 100 and 750 Pa inside and outside the fire zone was established,thus the variation of oxygen concentration inside the fire zone with time under the multi factor coupling influence of different pressure difference,volume of fire zone,wind resistance,gas emission and closing time due to the respiratory effect was obtained to evaluate the risk of fire zone.The results showed that the underground atmosphere fluctuated periodically with the ground atmosphere,and the pressure difference inside and outside the closed fire zone presented the periodic variation of 16 hours cosine fluctuation and 8 hours linear fluctuation due to the external atmosphere fluctuation.The fire zone with good closing quality had better anti interference,and the reduction of internal oxygen concentration mainly depended on the gas dilution.For the fire zone with poor closing quality,the internal oxygen concentration was vulnerable to the influence of both gas emission of fire zone and air inflow from outside.The oxygen concentration in the fire zone fluctuated between 2% and 12%,so that there existed the possibility of gas explosion in the fire zone.When the pressure difference inside and outside the fire zone was larger,the fluctuation variation amplitude of oxygen concentration was greater,and the duration of dangerous effect was longer.Combined with the model of oxygen concentration fluctuation in the fire zone,the safe preventive measures can be effectively taken to avoid the gas explosion accident in the fire zone of mine.