再生顶板条件下煤自燃危险区域空间分布特征

Research on spatial distribution pattern of coal spontaneous combustion hazardous zone under condition of regenerated roof

为避免煤层开采过程中再生顶板遗煤自燃,明确其内部流场特性,探究煤自燃危险区域动态特征,以山东某矿再生顶板遗煤自燃特性分析为例,采用数值模拟方法,对比分析采空区及再生顶板在不同风量下的漏风特征,并结合再生顶板结构特性,基于氧气质量分数与漏风速度复合指标,采取投影叠加判定新方法,确定煤自燃危险区域范围。研究结果表明:采空区深度小于60 m时,氧气质量分数逐渐减小,60 m后氧气质量分数不再受风量影响;而再生顶板氧气质量分数分布具有非对称性,在回风巷尾端会形成一个“三角形”中空区域。采空区在倾向上20~40 m范围内发生漏风回流,而再生顶板漏风速度分布呈“U”型对称分布。采空区煤自燃危险区域变化特征与氧化带相类似,而再生顶板煤自燃危险区域范围主要分布在靠近进风巷中部及回风巷前中部内侧区域,且随风量的增加,危险区域面积逐渐增大并逐渐向尾部延伸。

In order to avoid the spontaneous combustion of residual coal from the regenerated roof during coal mining,the characteristics of interior fluid field were clarified,and the dynamic law of coal spontaneous combustion hazardous zone was explored.Taking the spontaneous combustion features of residual coal from the regenerated roof of a mine in Shandong province as an example,the numerical simulation method was used to simulate and compare the air leakage characteristics of goaf and regenerated roof under different air volume.Subsequently,based on the structural characteristics of the regenerated roof,the scope of coal spontaneous combustion hazardous zone was determined by adopting a new method of projection superposition judgment with oxygen concentration and air leakage speed as comprehensive indexes.The results of the study show that the oxygen mass fraction of goaf decreases gradually when the depth is smaller than 60 m,while it's no longer affected by the air volume when the depth exceeds 60 m.The oxidation zone is asymmetrically distributed,forming a"triangle"hollow area at the end of the return airway.The air leakage and backflow occurs in the range of 20-40 m in dip direction of goaf,whereas the air leakage velocity of regenerated roof presents a U-shaped symmetrical distribution.The change features of coal spontaneous combustion hazardous zone in the goaf resemble those of the oxidation zone.In contrast,the coal spontaneous combustion hazardous zone in the regenerated roof is mainly distributed near the middle of the intake airway and the inner part of the front middle of the return airway,and the area of coal spontaneous combustion hazardous zone gradually expands and extends towards the tail with the increase in air volume.