综放采空区瓦斯与煤自燃多场耦合模拟研究

为了分析瓦斯与煤自燃多场耦合致灾特性，结合瓦斯抽采引起的采空区混合气体流动、气体组分渗流与采空区渗透率变化、固气两相热量传输等多物理过程，建立了基于综放采空区高位钻孔瓦斯抽采的热-流-化多场耦合数学模型，采用COMSOL软件模拟了综放采空区高位钻孔抽采瓦斯诱导煤自燃过程，阐明了瓦斯与煤自燃多场耦合致灾机理，得到了寸草塔二矿31102综放采空区氧化带范围与高温范围，并探讨了抽采强度对综放采空区氧浓度场与温度场的影响。研究结果表明:高位钻孔抽采瓦斯有效地降低了回风巷瓦斯浓度，保证了31102综放工作面安全高效回采。增大综放采空区高位钻孔抽采瓦斯强度不能保证煤自燃安全性，二者存在矛盾，在得到高效抽采瓦斯的同时，会造成进风侧氧化带宽度增加，采空区氧化带边界向深处蔓延，扩大煤自燃高温区域，漏风携氧充分的参与煤氧复合反应，采空区最高温度逐渐上升，煤自燃风险增大。

Simulation study on multi field coupling of gas and coal spontaneous combustion in goaf of fully mechanized caving face

Combined with the multi physical processes such as mixed gas flow in the goaf caused by gas drainage,gas component seepage and permeability change in the goaf,and solid gas two phase heat transfer,a thermal fluid chemical multi field coupling mathematical model based on the high level borehole gas drainage in the goaf of fully mechanized caving face was established.The COMSOL software was used to simulate the spontaneous combustion process of coal induced by gas with high level borehole drainage in the goaf of fully mechanized caving face,and the disaster causing mechanism of multi field coupling of gas and coal spontaneous combustion was clarified.The oxidation zone range and high temperature range of 31102 goaf of fully mechanized caving face in Cuncaota No.2 Mine were obtained,and the influence of drainage intensity on oxygen concentration field and temperature field in goaf of fully mechanized caving face was discussed.The results showed that the high level borehole gas drainage effectively reduced the gas concentration in the return air passage,which ensured the safe and efficient recovery of 31102 fully mechanized caving face.Increasing the intensity of high level borehole gas drainage in the goaf of fully mechanized caving face could not guarantee the safety of coal spontaneous combustion,and there existed the contradiction between them.When getting the high efficiency gas drainage,the width of oxidation zone on the inlet side would increase,and the boundary of oxidation zone in the goaf would spread deeper,so the high temperature area of coal spontaneous combustion would expand.Then the air leakage with oxygen would fully participate in the coal oxygen complex reaction,and the highest temperature of goaf would gradually rise,so the risk of coal spontaneous combustion would increase.