不同孔隙率对采空区自燃的影响规律研究

Study on the Influence of Different Porosity on Spontaneous Combustion in Goaf

为探究煤矿采空区在不同孔隙率条件下对煤自燃环境的影响,基于多孔介质渗流特性的相关理论,以煤矿综采工作面为原型建立了U型通风采空区三维模型和渗流数学模型,利用Fluent软件对采空区以不同的孔隙率大小和分布方式进行数值模拟计算,从而得到采空区的漏风和氧气浓度的分布状态,以及氧化带的位置变化情况,进而研究不同孔隙率对采空区煤自燃环境的影响规律。研究表明:采空区漏风主要源于工作面下隅角处,进入采空区的漏风量大小与采空区的孔隙率有关。孔隙率越大,靠近工作面的漏风流速越大,氧气浓度越高,而深入采空区,孔隙率大小对采空区漏风影响越小,氧化带随着孔隙率的增大不断向采空区深部移入;孔隙率分布方式对采空区漏风速度的影响较大,且距离工作面越近影响越大,采空区深部则差别不大。

To explore the influence of coal goaf on coal spontaneous combustion environment under different porosity conditions,based on the theory of seepage characteristics of porous media,the three-dimensional model and seepage mathematical model of U type ventilation goaf are established according to the fully mechanized coal mining face.Fluent software is used to simulate the air leakage and oxygen concentration in goaf and the change of oxidation zone under the different porosity and distribution style so as to further research the influencing law of spontaneous combustion surrounding by different porosity in goaf.The research shows that the air leakage in the goaf mainly originates from the coupling angle under the working face and the amount of air leakage entering the goaf is related to the porosity of goaf.The larger the porosity,the greater the air leakage velocity near the working face and the higher the oxygen concentration,while the deeper the goaf,the smaller the influence of porosity on the air leakage in the goaf,and the more the oxidation zone moves into the deep goaf with the increase of porosity.The distribution style of porosity has the largest influence on the velocity of air leakage in the goaf.