基于非达西渗流的采空区自然发火数值模拟

摘要

In order to research the spontaneous combustion in goaf based on the non-darcy seepage flow,the seepage tests were conducted on four groups of broken rocks which were in different average particle sizes, and then the test da- ta were processed with the non-Darcy seepage equation to achieve the formulas of non-Darcy permeability coefficient K with porosity n and particle size d, non-Darcy flow factor fl with the n and the d. These formulas were applied into the goaf according to the Renault criteria in fluid dynamic similarity criteria. Combined with the characteristics of the goal dynamic moving, the mathematical spontaneous combustion model on the coupling of air flow field, residual coal tem- perature field and oxygen concentration field was established ,then a numerical computation software was programmed by using Finite Volume Method. To the goaf of Hedong Coal Mine as an example, the oxygen concentration and the re- sidual coal temperature distribution map in goal was obtained through the software under different advance speed of working face. Finally, the analysis indicates that accelerating the speed can significantly reduce the spontaneous corn- bustion dangers in the goal%为了研究非达西渗流下的采空区自然发火情况,对4种不同平均粒度的破碎岩样分别进行了稳态渗流实验,再对得到的数据按非达西方程处理,然后进行二元拟合得到非达西渗透系数K与孔隙率n和粒度d的关系式以及非达西流因子β与n和d的关系式。依据流体动力相似准则的雷诺准则将这些关系式推广应用到实际采空区,结合采空区动态移动的特点,建立了移动坐标下的采空区漏风流场、氧浓度场和温度场相耦合的自然发火数学模型,利用有限体积法编制了数值解算程序。以河东矿31005工作面的采空区为例,解算得到了不同推进速度下的氧浓度场和垮落煤岩温度场的分布情况,比较分析后得出加快推进速度能显著降低该采空区自然发火危险。