深井采空区煤自燃多场耦合作用及致灾机理研究

Based on the characteristics of high stress and high ground temperature in the deep coal mine, the multi-field coupling effect and mechanism of the spontaneous combustion of the left coal in deep coal mine goaf will be researched. In this project, the coupling effect of the stress field, seepage field, and temperature field of the goaf on the spontaneous combustion of the coal left behind in deep coal mine goaf is the main line, to improve the accuracy of prediction and prediction of spontaneous combustion in deep coal mine goafs. Using theoretical analysis, numerical calculations, laboratory tests, and on-site application research methods, using heat transfer theory, seepage mechanics, fluid mechanics, and porous media, and related theories, the influence mechanism of coal mine goaf stress on coal spontaneous combustion environment will be researched. The change rule of predictive index gas for coal spontaneous combustion under different ground temperature conditions will be researched, and the mechanism of secondary oxidation of coal left behind in goaf by water immersion and air drying under high ground temperature conditions will be revealed. Constructing multi-physics coupling models and control equations for deep coal mine goafs to reveal the coupling mechanism of multiple physical fields such as stress field, seepage field and temperature field. The mechanism of multi-physics coupling effect on coal spontaneous combustion in goaf will be researched. The proposed research results will provide theoretical support for the prevention and control of spontaneous combustion of residual coal in the goafs of deep coal mine, provide technical support for disaster relief decision-making, help reduce or avoid the occurrence of secondary disasters, and enrich the theory of coal spontaneous combustion mechanism, which has important theory and practice application prospects.

基于深井煤矿开采高应力、高地温的特点，旨在研究深井采空区遗煤自燃多场耦合作用及致灾机理，本项目以采空区应力场、渗流场以及温度场对深井煤矿采空区遗煤自燃的耦合作用为主线，立足于提高深部煤矿采空区自然发火预测预报准确性的根本目的，采用理论分析、数值计算、实验室测试以及现场应用的研究方法，利用传热学、渗流力学、流体力学以及多孔介质等相关理论，研究深部煤矿采空区应力对煤自燃环境的影响机制，研究不同地温条件下煤自燃预测预报指标气体的变化规律，揭示高地温条件下水浸和风干对采空区遗煤二次氧化作用机制，构建深井采空区多物理场耦合模型及控制方程，揭示应力场、渗流场、温度场等多物理场的耦合作用机理，研究多物理场耦合作用对采空区煤自燃的影响机制。拟研究成果将为深井采空区遗煤自燃灾害防治提供理论支撑，为救灾决策提供技术支持，有助于减少或避免继发性灾害的发生，丰富煤自燃机理理论，具有重要的理论和实践应用前景。

本项目依据深部开采出现的高应力、高地温等问题，研究了深井开采采空区内遗煤自燃多场耦合作用及致灾机理。通过数值模拟计算，建立了深部采空区上覆岩层孔隙率和渗透率的空间三维数学模型；根据上覆岩层塑性区分布情况、位移变化及应力分布特征，得出“两带”的范围，得到了覆岩塑形破坏范围和破坏深度随着工作面的推进的变化规律。随着工作面的推进，深部开采过程中覆岩应力水平都不断增大，应力变化距离煤层越远越平缓，增长幅度在靠近煤层处更为剧烈。运用渗流力学、分子扩散与传质等理论分析了近距离煤层作为多孔介质具有的特性，得到了上覆采空区气体运移理论、水平和垂直方向的裂隙分布情况和近距离煤层自燃发火的特点、影响因素。通过建立采空区上覆岩层孔隙率和渗透率的空间三维数学模型，得到越深入采空区深部，氧浓度越小，瓦斯浓度越高的裂隙带气体分布规律；通过分析采空区压力场、渗流场及气体浓度场分布特征，初步判定了深部采空区煤自燃危险区域。根据实验分析与理论计算，提出了不同地温条件下指标气体的变化规律以及氧化动力学的煤自燃预测预报方法。对比分析经过不同初始温度处理煤样与原煤在孔隙结构上的差异，得出了高温处理的煤样的孔隙演化过程，模拟了高地温影响下松散煤体的氧化燃烧规律。采用氧化动力学测试系统，实时测量浸水风干煤体标志性气体的变化规律，计算了活化能、最小煤堆厚度、下限氧浓度、上限漏风强度煤自燃测定参数。从物理结构的演变和化学微观官能团的转化规律的测定，得到水浸过程对煤孔隙结构特征和微观表面形貌变化的影响，揭示了水浸前后煤中主要活性基团的迁移规律，结合微观分子转化得出水浸煤氧化活性增强的内在机理。针对不同风速、地温、应力下深部采空区煤自燃多场分布的规律，建立了耦合作用下深井采空区煤自燃发火危险区域判定准则。研究结果对深井采空区遗煤自燃的扑灭，完善高温和高应力状态下多场耦合煤自燃演化机制，提高煤自燃预测以及丰富矿井火灾防治的准确性，具有十分重要的理论和现实意义。