采空区不同瓦斯抽采方法与自燃合理平衡的数值模拟

Numerical simulation on reasonable balance between different gas drainage methods and spontaneous combustion in gob area

为了研究和解决西铭矿在生产中由于瓦斯抽采方法的不同可能引起采空区自燃以及瓦斯爆炸等重大安全隐患问题,构建了高位巷、埋管和高低位钻孔瓦斯抽采方法下的非均质多孔介质三维模型。利用非线性渗流定律、通用控制方程和自定义的函数进行解算,结果表明:高位巷、高低位钻孔抽采流量与抽采氧气浓度近似呈正比函数关系,埋管抽采流量与氧化带宽度呈指数函数关系;高位巷、高低位钻孔随着抽采流量的增加抽采效率反而降低,抽采总量增加,埋管抽采位置在距工作面35m处、抽采流量为20m3/min能很好解决上隅角瓦斯超限问题。根据模拟结论:采用立体联合瓦斯抽采方法既能满足抽采要求又能有效控制采空区自燃现象。

In order to study and prevent the potential safety problems of spontaneous combustion and gas explosion in gob area caused by different gas drainage methods in Ximing coal mine, a three-dimensional numerical model of heterogeneous porous media was established for simulating gas drainage with different methods including high level entry method, buried pipe method, and high and low level borehole method. The nonlinear percolation law, gener- al control equations and the self-defined functions were used for resolving the model. The results showed that： the gas drainage flow rate is directly proportional to the concentration of extracted oxygen when the high level entry and high and low borehole methods are used, while an exponential function relationship between gas drainage flow rate and width of oxidation zone appears when the buried pipe method is used. With the high level entry and high low borehole methods, the incremental drainage efficiency reduces when the drainage flow rate increases, but the total drainage amount increases. Gas exceeding limits in the upper comer can be prevented fairly well when the drainage position is 35 m away from the working face, at the flow rate of 20m3/min with buried pipe method. The three-dimensional combined gas drainage method can not only meet the requirements of drainage, but also control the spontaneous combustion in the gob area effectively.