浅埋近距离煤层群开采自燃火灾系统防控机理研究

The critical problems of shallow close distance coal seam group mining process are that multiple fractures connected to each other which lie in various layers even with the surface are inclined to leading spontaneous combustion in the goaf of coalface and recrudescence of the residual coal upper the goaf. Be aimed at solving these problems, a research that is based on theoretical analysis and the scene actual measurement data of coalface and goaf is put forward as following: establish the physical model of multilayer goaf of shallow close distance coal seam group mining process, through the test of 3D experimental table about coal spontaneous combustion and simulation of multi-field solid-fluid coupling software, discuss the deformation and rupture of overlying strata and coal pillar and the distribution of fracture field; measure and analyze the data that fractures are connected with three-dimensional space air leakage field under the pressure difference, and establish the mathematical model of air leakage field of multilayer goaf; get the key parameters data of local dynamic balance which is controlled by ventilation, establish multi-point dynamic voltage scaling balance system under the condition of connectivity of multilayer goaf and research and develop matching real-time dynamic monitoring and self-feedback control spontaneous combustion of multilayer goaf prediction and control systems. Experimental determination and analysis adopt a multi-point dynamic voltage regulating balance, stereo injection index gas (CO2), in combined with the control of systems including resistance of the modified and plugging fracture ect, air leakage field, temperature and index gas of spontaneous combustion change variation, and carry on an exploratory research about sealing mechanism that index gas (CO2) is adsorbed and transformed in the goaf. The project could lay a foundation for systematic prevention and control of coal spontaneous combustion in shallow close distance coal seam group mining process and similar conditions.

浅埋近距离煤层群开采中，多层多条裂隙连通甚至与地表贯通，易造成回采工作面采空区自燃和上方采空区遗煤复燃。基于理论分析和采场与采空区实测数据，建立浅埋近距离煤层群开采多层采空区物理模型，借助三维煤自燃实验台测试和多场固流耦合软件模拟计算，研究回采工作面上覆岩层和煤柱的变形破断及裂隙场发育规律；测定和分析不同压差下采空区裂隙连通立体空间气体流速和压力数据，建立其气体流场数学模型；获取通风控制的局部动态平衡关键参数数据，建立多层采空区裂隙连通的多点动态调压平衡系统，并研发实时动态监测和自反馈的煤自燃预测预报和控制平台。测试和分析采取多点动态调压平衡、立体注惰（CO2），结合阻化改性和封堵裂隙系统防控下，采空区漏风场、自燃指标气体和温度的变化规律，并探索性研究注惰气体（CO2）在采空区中吸附转化的封存机制。项目为系统防控浅埋近距离煤层群开采和类似条件的煤自燃火灾提供基础。

我国山西、内蒙古等矿区浅埋近距离煤层群赋存广泛。我国目前大都采用全部垮落法开釆，下层煤层开采后，使得多层相邻新老采空区相互不同程度地连通，甚至和地表贯通，形成复杂的复合釆空区。我国多采用负压通风方法通风，这将导致釆空区漏风量大，釆空区灾害气体涌入生产工作面，易造成自燃火灾，如果回采过程中需要抽采采空区瓦斯，就还涉及到瓦斯和火灾共生灾害的协调防控问题。因此，浅埋近距离煤层群开采自燃火灾防治问题的研究显得十分迫切，意义重大。本项目基于理论分析和采场实测数据，建立浅埋近距离煤层群开采多层采空区物理模型，研究采场上覆岩层裂隙场发育，研究多层采空区立体空间气体流场数学模型，研究多层采空区气体多点动态调压平衡方法和关键参数，并研发实时动态监测和自反馈的煤自燃预测预报和控制装备，探索性地研究了注惰气体（CO/N2）防灭火和封存机制。项目开展以来，项目组综合运用调研、理论分析、数值计算、实验室实验、现场验证等手段，获得了浅埋近距离煤层群上下层开采过程中的围岩裂隙演化规律和气体流动规律；阐述了浅埋近距离煤层群开采复杂采空区致灾特点和防控机制；分析了浅埋近距离煤层群采空区自燃危险区域分布规律，以及采用常规单一措施和综合措施预防自燃的机制；以恒大煤矿为例，研究获得了近距离煤层群开采条件下的瓦斯抽采与自燃分区防控效应及调控的方法；以山西四台矿为例，研究了浅埋近距离煤层群采场风流动态平衡调控方法和参数，研发了关键装备并现场应用。总之，本项目完善了浅埋近距离煤层群开采复杂条件下的防灭火机理理论，为复杂多层采空区火灾综合防控提供了新的方法、技术和装备支撑，为煤矿自燃火灾的智能防控奠定了一定基础。