炮采放顶煤采空区自然发火的数值模拟应用

Numerical simulation on the spontaneous combustion prevention in goaf of blasting coal caving face

针对炮采放顶煤开采采空区容易发生自燃问题,基于漏风渗流方程、气体渗流-扩散-氧消耗方程,建立了采空区自然发火非稳定数值模型,采空区按非均质考虑,耗氧汇按煤矸氧化和瓦斯涌出稀释两方面综合考虑,用有限元数值方法联立求解模型。结合羊草沟矿实例,通过该矿自然发火后来的测试区的现场实测结果,拟合反演得到采空区煤的耗氧速度、瓦斯涌出强度和渗透特征参数,用确定的模型分析了前段出现自然发火的原因；描绘了炮采放顶煤开采时采空区冷却带、自燃带和窒息带等三带的形状,指出冒落压实的不均衡的非均质采空区,自燃点在偏入风一侧。用三带划分理论讨论了工作面参数(风量、推进度、控顶距)同自燃的量化关系,提出了从根本上预防采空区自然发火的途径与方法。

The unstable numerical model of spontaneous combustion in goaf is established, based on the seepage equation of leaking wind and the equation of gas seepage -diffusion-oxygen consumption. Supposing the goaf is homogenous, the consumption of oxygen is taken into account from the following aspects： the oxidizing of coal gangue and the outburst of methane. The model is resolved according to the simultaneous equation of numerical method finite element . The velocity of oxygen consumption, the out bursting intensity of methane and coefficient of permeability were obtained by fitting and inversing the on-site data from the Yang Cao-gou. The three girdles-cooling girdle, spontaneous combustion girdle, asphyxia girdle in goaf when blasting coal caving face was applied were pertained by definitive model, pointing out the spontaneous combustion place is where the unilateral entering wind in the heterogeneous goaf because of disequilibrium caving compaction. Furthermore, the quantizing relative between parameter of work face and spontaneous combustion was discussed, the paths and methods for the precaution of spontaneous combustion in goaf were given at the same time.