采空区煤自燃多场叠加作用机制及影响效应研究

The disaster of coal spontaneous combustion of China is serious now. With the increase of mining depth, the crust stress, temperature and fragmentation degree of residual coal will increase too. And the disaster of coal spontaneous combustion will be more serious which is leaded by the characteristics above. Actually, the coal spontaneous combustion of goaf occurred in the air leak and oxygen supply conditions. Different crust stress influence the amount of air leak. Different amount of air leak influence the concentration of oxygen, gas etc. and further influence the exothermic oxidation ability of coal. So obviously, the process of coal spontaneous combustion should be closely related to the crust stress filed, atmosphere field and temperature field, and the three filed have relation with each other. In this project, the independent development of multi field superimposed experimental system of coal spontaneous combustion will intend to be used to study and reveal the spontaneous combustion oxidation law of loose coal under crust stress – temperature – atmosphere field, and to obtain the relation of crust stress, temperature and atmosphere. Through experiment, the spontaneous combustion and oxidation macroscopic representation of loose coal under crust stress – temperature – atmosphere field and the influence on the process of coal spontaneous combustion under combined factors can be obtained. And then the coal spontaneous combustion under the impact of seepage field, temperature field and atmosphere field can be analyzed. Multi field superposition mechanism of coal spontaneous combustion in goaf can be constructed. The research findings can supply and improve the existing coal spontaneous combustion prevention theory. And at the same time, it has a great spot guidance effects on preventing coal spontaneous combustion disaster.

我国煤矿煤层自燃灾害形势严峻，且随着开采深度增加而呈现出地应力增加、地温升高、遗煤破碎程度增大等特点，导致煤自燃灾害越发严重。采空区煤自燃的发生实际上是在适当漏风供氧环境条件下进行的。不同的采场应力场影响漏风量，不同的漏风量影响采场中的氧气、瓦斯等气体浓度，进一步影响煤的氧化放热能力。显然煤自燃的过程与采场应力场、气氛场、温度场密切相关，且三场之间存在相互关系。本项目拟利用自主开发的煤自燃多场叠加实验系统，研究并揭示松散煤体在应力-温度-气氛多场叠加下的采空区遗煤自燃氧化规律，得到应力、温度、气氛三场耦合作用关系；实验得到松散煤体在应力-温度-气氛多场叠加下的煤自燃氧化宏观表征及组合因素下对煤自燃进程的影响。进而分析采空区渗流场、温度场、气氛场对煤自燃的影响效应，构建采空区遗煤自燃环境的多场叠加作用机制。研究成果可补充完善现有煤自燃防治理论，同时对煤自燃灾害的防治具有极大的现场指导作用。

我国煤矿煤层自燃灾害形势严峻，且随着开采深度增加而呈现出地应力增加、地温升高、遗煤破碎程度增大等特点，导致煤自燃灾害越发严重。. 本项目利用自主设计研发的承压破碎煤体渗透演化及自燃特性测试装置，并将其与GC-4000A系列气相色谱仪连用，研究并揭示松散煤体在应力-温度-气氛多场叠加下的采空区遗煤自燃氧化规律。通过模拟煤体在不同应力状态及围岩温度下空隙率、渗透率的变化特征及响应机制，获得松散煤体在应力-温度场耦合作用下的渗透特性演化规律，并在此基础上，研究松散煤体在应力-温度-气氛多场叠加下的采空区遗煤自燃氧化规律。. 为描述采空区煤自燃过程中各物理场随工作面推进的动态变化，实现推进过程中采空区几何边界移动步距与物理场分布变化的相适应性，本项目提出了一种“定坐标系，变物理场”的非稳态模拟方法，分析工作面推进对采空区遗煤所处渗流和氧化环境的动态影响。基于所建立的模拟方法，模拟了义马矿区13210工作面不同推进距离下及推进速度下采空区渗流参数、氧气浓度场和温度场的动态分布，并通过现场实测与模拟结果比对，验证了模拟方法的可行性，模拟结果的正确性。. 通过本项目的研究，发现了煤体在轴向应力的压实作用下二次破碎，形成更小的颗粒封堵有效空隙，导致煤体空隙率和渗透率降低。空隙率降低造成煤体的导热系数增大，且煤体更易形成自由基，有利于煤氧复合的发生。渗透率降低导致煤体升温氧化产生的热量更加容易积聚，在一定的范围内耗氧量和放热强度增大，煤体的氧化进程加快，促进了煤自燃的发生。随着轴向应力的继续增加，破碎煤体进一步的压实，空隙率和渗透率继续降低，导热系数增大导致放热强度和耗氧速度增加，需要消耗更多的氧气，煤氧化进程进入贫氧状态，从而抑制了煤自燃的发生，揭示了承压破碎煤体氧化差异性形成的致因。研究成果可补充完善现有煤自燃防治理论，同时对煤自燃灾害的防治具有极大的现场指导作用。