多场耦合作用下瓦斯与煤自燃协同预防数值模拟

为解决某综放面采用顶板巷与上隅角联合抽采方式可能引起的煤自燃及瓦斯爆炸等重大安全隐患问题,采用数值模拟从瓦斯、氧气体积分数分布特点和温度场角度综合分析合理顶板巷位置与抽采流量,为协同预防瓦斯和煤自燃复合灾害提供指导。结果表明:抽采口、上隅角瓦斯体积分数随抽采流量增加而降低;抽采流量100m3/min是影响氧化带宽度变化幅度的拐点;抽采流量对采空区最高温度的影响较大,对高温范围宽度影响较小;综合确定合理顶板巷位置为内错回风巷15 m,合理抽采流量为100~150 m~3/min;现场应用表明该方案既能解决瓦斯超限问题,又能有效控制煤自燃威胁,表明数值模拟具有较好的可靠性。

Numerical simulation of synergistic prevention from the gas and coal spontaneous combustion under multifield coupling

In order to study and solve the serious safety problem of spontaneous combustion and gas explosion caused by the gas drainage from the roof entry and the upper-corner T-junction in the underground coal-mine,the paper has made a numerical simulation for analyzing the distribution of the gas and oxygen content concentration rates at a top-caving working face by using the different gas drainage methods. In our exploration and analysis,we have managed to identify and determinate the reasonable location of the roof entry and pumping flow rate by taking into account the comprehensive influential factors,such as the gas,oxygen and temperature under the roof entry and the upper corner of the Tjunction, all of which can help to provide the guides for synergistic prevention of the gas and spontaneous combustion risk disasters. As a result,we have made it clear that,though it is possible to reduce the gas concentration rate by extracting the gas density from the roof entry and the upper corner,there still exist likelinesses for the safety risks of spontaneous combustion of the residual coal to take place in the gob at the same time. Therefore,we have also made an investigation of the gas concentration,the broadth of the oxidation band and pumping flow rates in different positions of the roof entry at different temperatures,for the gas concentration may decrease with the increase of the pumping flow rates at the drainage outlets and the upper corners,for instance, the pumping flow rate of 100 m3 /min is actually the inflection point which may affect the range of the oxidation band,and tends most likley to further affect the maximum temperature of the gob area,though little influence on the range of high temperature. Since the reasonable location of the roof entry can be identified and determined to be 15 m away from the return airway towards the gob side and the reasonable pumping flow rate at the position of 100-150 m3 /min synthetically. The engineering practice shows that this scheme can not only mitigate the gas overrun and meet the demands of the gas drainage in addition to the control of the problem of spontaneous combustion of coal effectively,the numerical simulation that we have done can thus be expected to be most reliable and serves as a basis and guide to the other mines with the similar conditions.