【作者】 陶云奇；

【导师】 许江；

【作者基本信息】 重庆大学 ， 安全技术及工程， 2009， 博士

【摘要】 煤是一种孔隙-裂隙双重介质,瓦斯在煤层中的流动是流固耦合作用下的瓦斯流动,煤与瓦斯突出亦是流固耦合作用下的煤体失稳破坏现象,而渗透率作为标志瓦斯在煤层中流动难易程度的指标和煤层瓦斯热-流-固耦合模型一起成为煤层瓦斯运移规律研究中最基础也最重要的问题,而煤与瓦斯突出模拟实验又是煤与瓦斯突出防治研究中最重要的技术手段。因此,选择重庆能源投资集团松藻煤电公司打通一矿8#煤层、石壕矿8#煤层以及平顶山煤业集团一矿戊8煤层和己15煤层所制煤样作为研究对象,以打通一矿8#煤层和石壕矿8#煤层为主,利用西南资源开发及环境灾害控制工程教育部重点实验室(重庆大学)的MTS815岩石力学试验机、VEGAⅡ型自带能谱扫描电镜、自主研发的煤与瓦斯突出模拟试验台和煤炭科学研究总院重庆研究院的HCA型高压容量法瓦斯吸附实验系统及含瓦斯煤三轴渗透实验系统等设备对煤层瓦斯运移规律及煤与瓦斯突出模拟实验进行了系统研究,并结合岩石力学和渗流理论从理论层面开展了一些有益的探讨,通过以上系统研究,在以下方面取得了一些结论或进展:1)根据渗透率实验和煤样扫描电镜及其表面孔隙分形特征研究,发现煤渗透率与其分形维数和孔隙发育程度成正相关关系,与其密度成反相关关系。2)提出了含瓦斯煤在外应力和内应力共同作用下存在结构变形和本体变形两种变形机制,建立了压缩条件下(扩容前)的含瓦斯煤孔隙率动态演化模型和吸附热力学参数表达的有效应力方程,经现场和已有实验资料验证,运用该模型预测未采区域含瓦斯煤孔隙发育程度和应力状态的误差相对较小。3)基于含瓦斯煤三轴渗透率实验,分析了有效应力、温度和瓦斯压力对其渗透率的作用规律,系统探讨了有效应力、温度和瓦斯压力分别对渗透率的影响机理,建立了压缩条件下(扩容前)煤渗透率动态演化模型,经渗透率实验验证,该模型预测煤渗透率精度较高,对提高瓦斯抽放效果具有理论指导意义。4)自主研发了“煤与瓦斯突出模拟试验台”,该试验台弥补了国内现有突出实验装置存在的不足,在结合相似理论探讨该试验台的模拟能力的基础上,进行了不同瓦斯压力、不同突出口径及不同煤粉粒径配比等条件下的煤与瓦斯突出模拟实验,依据所开展的11次煤与瓦斯突出模拟实验结果分析了煤与瓦斯突出过程中煤体温度、突出强度、孔洞形态和突出煤样粉碎性以及煤粉粒级分布的变化规律。5)在起纽带作用的物性参数耦合方程研究基础上,建立了体现热流固三场完全耦合的含瓦斯煤THM耦合模型,经二次开发将耦合模型嵌入多物理场耦合分析软件进行数值计算,经已有解析解的一维瓦斯渗流算例和煤与瓦斯突出实验室相似模拟实验印证表明,本文建立的含瓦斯煤THM耦合模型和数值计算方法具有一定的可靠性;并以重庆能源投资集团松藻煤电公司石壕矿S1824综采工作面为工程背景,分析了采煤工作面在一次采全高且刚掘出开切眼时煤层瓦斯渗流过程中各相关指标的变化规律,提出了一套进行煤层瓦斯渗流规律分析和数值计算的研究方法。更多还原

【Abstract】 Coal belongs to two-phase material of pore-fracture, in which gas flow is affected by fluid-solid coupling. Coal and gas outburst is a distabilizing and destructive phenomenon of coal which is also affected by fluid-solid coupling. Coal-bed permeability which indicates the difficult level of the gas migration in coal and the Thermal-Hydrological-Mechanical Coupling model of coal-bed gas are both the first and the most important for the study on migration rules of coal-bed gas. Coal and gas outburst simulation experiment is the most important technological means for the research of prevention and management of coal and gas outburst calamity. So this paper chooses coal samples which are from the original coal of the 8# coal-bed of Datong No.1 mine and the 8# coal-bed of Shihao mine of Chongqing Energy Investment group Songzao C&E CO.LTD., Wu8 and Ji8 coal-bed of Pingdingshan coal CO.LTD. No.1 mine as study objects, mainly with 8# coal-bed of Datong No.1 mine and Wu8 coal-bed of Shihao mine, by using MTS815 Rock Mechanics Test System, VEGAⅡscanning electron microscopy and self-development coal and gas outburst simulation test device of Ministry of Education Key lab. for exploitation of Southwestern Resources & Environmental Disaster Control Engineering (Chongqing University), and HCA high pressure volumetric method gas adsorption experiment system and gassy coal triaxial osmotic experiment system of Coal research institute Chongqing branch, to do the systematical research on the migration rules in coal-bed and the coal and gas outburst simulation experiment, meanwhile the paper combines rock mechanics and the seepage theory to do a helpful research from the theoretical aspect. Based on the above systematic study, the main research results and progress are as follows:1) According to permeability experiment, coal sample scan electron microscope and the research of fractal feature of surface layer porosity in this paper, it is found that permeability of coal sample is directly proportional to its fractal dimension and pore development but inversely proportional to its density,2) Two deformation mechanisms that are gassy coal integral deformation and primary deformation have been put forward under effective stress and temperature and gas pressure. Gassy coal porosity dynamical evolution model under compressive condition (before dilatancy) and effective stress equation expressed by the adsorption thermodynamics parameter have been established. That this model have less errors in predicting pore development and stress state of gassy coal in non-mining areas has been verified by field and existing experimental data.3) Based on gassy coal triaxial permeability experiment, the effect law of effective stress, temperature and gas pressure on permeability has been analyzed; meanwhile the mechanism of their own effect of the three factors on permeability has respectively been discussed. Coal permeability dynamical evolution model has been established under compressive condition (before dilatancy). Verified by the permeability experiment, this model has higher precision in predicting permeability of coal and has theoretical guidance significance for improving gas drainage effect.4) Coal and gas outburst stimulant test-bed is invented independently, which makes up for what domestic experimental devices is lack of. This test-bed is applied to the simulation experiment of coal and gas outburst under different gas pressure, different outburst caliber and different stress conditions, etc, and the paper also confirm the simulation capacity of the test-bed by Similarity theory. Based on the simulation experimental results of eleven times, it analyzes the change laws of temperature of coal, outburst intensity, hole configuration, comminution of outburst coal, as well as grain size distribution of coal in the process of the coal and gas outburst.5) Gassy coal THM coupling model is established based on parameter coupling equation which has the linking function, achieving thermal-hydrological-mechanical coupling. By embedding coupling model into COMSOL Multiphysics to do numerical calculation, proved by one-dimensional gas seepage calculation and coal and gas outburst simulated experiment, gassy coal THM coupling model and numerical method which are estabished in this paper are, to some extent, reliable. Based on the background of Shihao mine S1824 fully mechanized coal mining face of Chongqing Energy Investment group Songzao C&E CO.LTD., it analyzes the variable changing laws of related indexes in coal-bed gas seepage process in the condition of mining in lump in a time and just exhuming open-off cut, and put forward a series of study rules analyse and numerical methods on coal-bed gas seepage.更多还原