西部浅埋厚煤层高强度开采覆岩导气裂缝的时空演化机理及控制研究

发布时间：2018-08-30 07:51

【摘要】：针对西部矿区浅埋深、薄基岩和厚煤层的赋存特点和煤层开采过程中覆岩断裂裂缝贯通地表并导致地表漏风,并由此引起工作面通风紊乱、采空区CO浓度超限、存在遗煤自燃隐患等影响安全生产的问题。本文以内蒙古串草圪旦煤矿地质赋存及生产技术条件为背景,从覆岩结构运动与空气流动学的角度出发,综合采用现场实测、相似材料模拟、数值计算、理论分析、现场工业性试验等研究方法,对浅埋厚煤层高强度开采条件下覆岩失稳运动特征及断裂裂缝的动态分布与发展变化规律、覆岩导气裂缝的产生机理及其时空演化规律、导气裂缝影响下采空区流场及工作面漏风特征等进行了系统深入地研究,提出了基于覆岩导气裂缝控制的浅埋厚煤层开采安全保障技术。研究成果对于西部矿区浅埋厚煤层高强度开采岩层控制和安全生产具有重要的理论价值和现实意义。基于串草圪旦煤矿浅埋厚煤层开采工程地质条件,实测得出了不同埋深、覆盖层厚度条件下工作面地表采动裂缝时空分布规律、动态发育特征及其主控因素,以及地表漏风强度、采空区气体浓度分布规律及其相关关系。分析归类了地表采动裂缝的类型及其对工作面安全生产的影响。建立了覆岩承载关键层深梁结构力学模型,得出了深梁结构承载关键层初次破断和周期性破断的破断特征、失稳运动形式及其影响因素,以及覆岩贯通型地裂缝的形成机理。分析了承载关键层层位、基岩厚度、松散覆盖层厚度、工作面推进速度以及地表地形等对浅埋厚煤层开采覆岩破断失稳及断裂裂缝时空演化规律的影响,得出了覆岩断裂裂缝的动态时空演化特征、类型和分布范围。建立了浅埋厚煤层开采覆岩导气裂缝空气流动力学分析模型,分析了覆岩导气裂缝的导气机理及导气特征,确定了覆岩导气裂缝的分布特征、导气条件,得出了基于覆岩导气裂缝等效缝宽的浅埋厚煤层开采覆岩导气裂缝漏风流量q￠及平均漏风流速m￠的计算公式。通过现场实测分析和计算流体力学分析相结合,得出了覆岩导气裂缝在工作面推进方向上的时空分布规律,建立了覆岩导气裂缝的演化模型,为导气裂缝影响下采空区内漏风流场时空分布规律的分析奠定了理论基础。建立了基于导气裂缝控制的工作面安全生产保障条件,提出了保障工作面安全生产的技术途径。包括减缓覆岩导气裂缝内漏风流速的填平封堵技术,防止采空区覆岩导气裂缝漏风的工作面增压通风技术,预防采空区遗煤自燃的浅埋厚煤层开采采空区注浆、注氮技术及保证工作面一定推进速度等。
[Abstract]:Aiming at the characteristics of shallow buried depth, thin bedrock and thick coal seam in the west mining area, and the overlying rock fracture through the surface during the coal seam mining, which leads to the surface air leakage, and thus causes the ventilation disorder of the working face, the CO concentration in the goaf exceeds the limit. There are some problems such as hidden danger of coal spontaneous combustion affecting production safety. Based on the geological occurrence and production conditions of Cangcao Gedan Coal Mine in Inner Mongolia, from the point of view of overburden structure movement and air flow, the field measurement, simulation of similar materials, numerical calculation and theoretical analysis are adopted in this paper. Based on the field industrial tests, the characteristics of overburden instability movement, the dynamic distribution and development of fracture fractures, the generation mechanism and space-time evolution law of overburden gas fractures under the condition of high strength mining in shallow buried thick coal seam are studied. Under the influence of gas fissures, the flow field in goaf and the characteristics of air leakage in working face are studied systematically and deeply, and the mining safety guarantee technology of shallow buried thick coal seam based on gas crack control of overburden rock is put forward. The research results have important theoretical value and practical significance for the control and safe production of strata in high strength mining of shallow thick coal seam in western mining area. Based on the mining engineering geological conditions of shallow thick coal seam in Xuancao Gedan coal mine, the temporal and spatial distribution law, dynamic development characteristics and main controlling factors of mining cracks in working face under different buried depth and overburden thickness are obtained. And the air leakage intensity, gas concentration distribution in goaf and its correlation. This paper analyzes and classifies the types of surface mining cracks and their influence on working face safety. The mechanical model of the deep beam structure of the key strata bearing overburden is established. The fracture characteristics of the first and periodic breaking of the critical layer bearing the deep beam structure, the form of instability and its influencing factors, as well as the formation mechanism of the ground fracture of the overburden through type are obtained. This paper analyzes the influence of bearing key layers, bedrock thickness, loose overburden thickness, working face advancing speed and surface topography on the time-space evolution law of overburden rock fracture instability and fracture in shallow buried thick coal seam mining. The dynamic temporal and spatial evolution characteristics, types and distribution range of overburden fracture fractures are obtained. The air flow mechanics analysis model of overburden gas fracture in shallow buried thick coal seam is established. The gas conduction mechanism and gas conduction characteristics of overburden gas fracture are analyzed, and the distribution characteristics and gas conduction condition of gas fracture in overburden rock are determined. The formula of air leakage flow Q and average air leakage velocity m of overburden gas fracture in shallow buried thick coal seam based on equivalent fracture width of overburden gas conductivity fracture is obtained. Through the combination of field measurement analysis and computational fluid dynamics analysis, the space-time distribution law of overburden gas crack in the working face is obtained, and the evolution model of overburden gas crack is established. It lays a theoretical foundation for the analysis of the spatial and temporal distribution of air leakage field in goaf under the influence of gas conduction cracks. The working face safety production guarantee condition based on the gas guide crack control is established, and the technical way to ensure the working face safety production is put forward. It includes filling and plugging technology to slow air leakage velocity in overburden gas crack, working face pressurized ventilation technology to prevent air leakage from gas crack in overburden rock in goaf, and grouting in mining goaf in shallow thick coal seam, which can prevent spontaneous combustion of coal in goaf. Nitrogen injection technology and ensure the working face certain speed of advance, etc.
【学位授予单位】：中国矿业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TD325;TD728
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本文编号：2212438