采空区自燃火灾气体钻孔导流的数值模拟研究

针对采空区局部自燃火源点的火灾情况 ,提出用地面钻孔抽放采空区自燃火灾气体 ,使其避免流向工作面的方法。基于渗流方程和气体扩散方程建立了简化的采空区火灾气体移动———弥散数值模型 ,用迎风有限元方法结合图形显示技术求解。模拟了在抽放前后采空区火灾气体移动和CO浓度分布特征 ,该方法对火源位置的判定精度要求不高 ,但钻孔必须设在火源的后方。通过模拟试验 ,抽放后工作面向采空区漏风增加量约为抽放流量的一半 ;抽放流量与采空区CO绝对涌出量近似呈负指数关系 ,给出了最低抽放流量的表达式。这项研究 ,能为分析在短期内消除采空区自燃火灾气体对工作面影响和确定抽放参数提供一种辅助手段。

Study on Numerical Simulation for Gases from Spontaneous Combustion in Goaf by Boring Water Diversion

According to the situation of fire source from local spontaneous combustion in goaf, evacuating the gases from spontaneous combustion by boring from ground surface to prevent the gases flowing to working faces was adopted. A simplified move-diffusion numerical model for fire gases in goaf was established based on seepage equation and gas diffusion equation, and the model was solved by windward finite element method and graph display technology. The movement of fire gases in goaf and the distribution characters of CO concentration before and after evacuation were simulated. The method did not require a high precision in determination of fire source location; however, the boring must be set behind the fire source. By simulation experiments, the relation between evacuation flux and the absolute emission rate of CO that enters into working face was approximate negative exponent, and the expression of minimum evacuation quantity could be determined. The study provides a supplementary measure for analyzing how to eliminate the influence of spontaneous combustion fire gases in goaf on working faces in short period, as well as to determine evacuation parameters.