裂隙煤岩体损伤演化与渗流耦合试验研究.pdf

裂隙煤岩体损伤演化与渗流耦合 试验研究 重庆大学博士学位论文 学生姓名张先萌 指导教师张东明 专 业矿业工程 学科门类工 学 重庆大学资源及环境科学学院 二 O 一七年四月 国家科技重大专项课题2011ZX05040-001-005 万方数据 万方数据 Damage Evolution and Gas Permeability in Fractured Coal and Rock Mass  A Thesis ted to Chongqing University in Partial Fulfillment of the Requirement for the Doctor’s Degree of Engineering By Xian-meng Zhang Supervised by Dong-ming Zhang SpecialtyMining Engineering College of Resource and Environmental Science of Chongqing University, Chongqing, China April 2017 National Science and Technology Major Projects of China 2011ZX05040-001-005 万方数据 万方数据 中文摘要 I 摘 要 煤与瓦斯突出作为矿井生产中的自然灾害，是制约煤矿安全生产和经济效益 的重要因素。随着开采深度的增加，地下开采的条件和技术方法不断恶化，煤与 瓦斯突出的次数和强度将会不断增加，防突问题已成为国内外学者十分关注并为 此付出巨大精力和代价的研究课题。另一方面，煤层气是一种十分有用的清洁能 源，且我国煤层气储量巨大，与陆上天然气资源总量相当。此外，煤层气主要成 分为 CH4，作为温室气体的一种，如果任意排放不加以利用，会对环境造成恶劣 影响。因此，在煤炭生产过程中将抽采的瓦斯加以利用，无疑会取得安全生产、 经济与环境的多赢局面。本文选择平煤集团天安煤业十二矿的己15-17200 工作面 为主要研究对象，针对覆岩在采动影响下的裂隙煤岩体的损伤演化与渗流耦合之 间的关系进行研究，采用理论模型建立，实验室试验和数值模拟试验相结合的方 法对平煤集团煤与瓦斯共采实践进行深入探讨，提出煤层开采卸压区瓦斯抽采优 化设计方案，并通过现场试验进行实地验证，证明效果较好。取得成果如下 ①平煤集团己15煤层工作面前方主要分为卸压区，应力集中区，和原岩应力 区。并利用空心包体应变计法测量己15煤层瓦斯专巷的地应力状态，为后续研究 提供科学依据。 ②利用含瓦斯煤热流固耦合三轴渗流试验装置进行了不同轴压，不同围压， 不同瓦斯浓度的三轴渗流试验，试验结果能够有效模拟现场实际条件。建立了加 卸载条件下原煤损伤演化和瓦斯渗流耦合模型，并基于 BFGS 法进行验证，结果 表明，该模型能够有效反映卸围压原煤峰后损伤演化和瓦斯渗流规律。 ③自主研发的连续加压恒压煤岩流变试验装置，运行稳定，恒压效果好，试 验结果准确。所研制的五连杆扩力系统，最大扩力可达到 250 倍，可解决一般恒 压加载较小的缺点。并利用该设备进行了单轴稳定蠕变试验和三轴稳定蠕变试验， 并建立五元件粘弹塑性蠕变损伤本构模型，经 BFGS 算法验证，可能够有效反映 裂隙岩体蠕变损伤-渗流耦合规律。 ④由相似模型试验知直接顶和老顶岩梁破坏的主要形式均为拉破坏，并且顶 板翼端产生裂纹有向中间集中相交形成裂隙拱的趋势。结合 CXK6-Z 钻孔成像仪 对上覆岩体的破断规律进行现场观测知，煤层回采后上覆岩层形成的断裂带内破 断裂隙和离层裂隙共生，其中断裂带上部以离层裂隙为主，下部以破断裂隙为主， 且覆岩采动裂隙中穿层破断裂隙和岩层层面离层裂隙相互贯通，处于弯曲下沉带 的岩体产生离层裂隙和层内破断裂隙几率较大，产生层间破断裂隙较少。 ⑤对采动卸压区瓦斯主要来源以及含量进行了分析，确定了煤层开采卸压区 万方数据 重庆大学博士学位论文 II 的主要来源包括工作面的瓦斯涌出、采空区的瓦斯涌出和邻近煤层瓦斯涌出三大 类，并且得到了各类瓦斯涌出的基本表达式。煤层覆岩的卸压带和煤层底板的局 部化共同组成了瓦斯运移和富集主要区域。随着工作面不断推进，瓦斯形成了一 个类似裂隙拱区域的流量拱区域。流量拱区域具有明显的不对称性，靠近工作面 的区域瓦斯浓度较高。 ⑥结合己15-17200 工作面的实际地质条件，采用顺层预抽钻孔和底抽巷穿层 预抽钻孔区域瓦斯抽采措施相结合的方式进行瓦斯抽采实践。在此基础上，提出 利用既有瓦斯专巷条件下的煤层卸压区穿层钻孔的瓦斯抽采方式，进一步提高瓦 斯抽采效率。煤与瓦斯共采效率提高效果明显，为煤与瓦斯共采模式提供了新的 思路，具有重大的经济和社会价值。 关键词关键词含瓦斯原煤；渗透率；损伤演化；体积应变；准牛顿法 万方数据 英文摘要 III ABSTRACT Coal and gas outburst is a major natural disaster in mine production, which is one of the key factors that restrict the safety production and economic benefit of coal mine. With the increase of mining depth, underground mining geological and mining technology conditions continue to deteriorate, the number and intensity of coal and gas outburst increased. The problem of outburst prevention has become a research subject that scholars at home and abroad pay great attention and pay great energy and cost. On the other hand, coal-bed methane is a coal-layer associated product, which is a very useful clean energy, huge reserves, almost the same as the total amount of natural gas resources on land in China. In addition, the main component of coal-bed methane is CH4, as a kind of greenhouse gas, if any emissions are not used, will cause adverse environmental impact. Hence, undoubtedly achieve safe production, economic and environmental win-win situation if we fully utilization of the extracted gas in the process of coal production. In this paper, the Ping Dingshan Tian Coal Co. Ltd. operated the No.12 mine of Ping Dingshan mining area belong to Henan province. The No.17200 working face and its overlying rock mass as the subject investigated. Research on relationship between damage evolution and seepage coupling of fractured coal and rock mass under the influence of mining. Based on the combination of theoretical model, laboratory test and numerical simulation test, which discusses the practice of the coal and gas co-mining in Ping Dingshan Coal Group. The optimal design scheme of gas extraction in the pressure relief zone of ultra-long distance coal seam put forward and verified by field test to prove the effect is better. The following conclusions were drawn. ①The front working face of the coal seam in Pingdingshan Coal Group is mainly divided into the pressure relief zone, the stress concentration area, and the original rock stress zone. By using the of hollow body strain gauge to measure the stress state of the gas tunnel in the No.15 coal seam, which provides scientific basis for the follow-up study. ②By using the self-developed tri-axial servo-controlled seepage equipment for thermal-fluid-solid coupling of coal containing gas, the law of raw coal seepage at different gas pressures and different moisture content was investigated, the test results can be used to simulate the practical conditions. Established the coupling model of coal damage and gas seepage flow under the loading-unloading conditions, and based on the 万方数据 重庆大学博士学位论文 IV BFGS for verification. The results show that the model can well reflect the damage evolution and gas seepage of the coal after the pressure. ③The self-developed constant pressure coal-rock rheological test device for continuous pressure. The development of the five-link expansion system with the maximum expansion can reach 250 times, which can solve the problem of the general pressure loading. The uniaxial stability creep test and the tri-axial stability creep test carried out. The constitutive model of viscoelastic and plastic creep damage of the five elements was established. Based on the BFGS algorithm, which can well reflect the creep damage-seepage coupling law of fractured rock mass. ④It is found that the main failure of immediate roof and main roof rock beam failure is tensile failure by similar-simulation test, and the top of the top plate has a tendency that the crack has a centrally concentrated intersecting to a fissure arch. Combined with the CXK6-Z borehole imager, the breaking law of the overlying rock mass observed. The breaking fissures and separated fractures ed in the fracture zone by the overlying strata after coal mining, the upper part of the fault zone is mainly breaking fracture, and the fractured faults in the fractured faults of the overlying strata and the fractures of the strata in the rock strata are interconnected. The rock mass in the bent subsidence zone has a relatively high probability of fracture and crack, generate the less breakage in the layers. ⑤Analyze the main sources and contents of the gas in the depressurization area of the mining, which determined that the main sources of the coal seam depressurization area include the gas emission in the working face, the gas emission from the goaf and the gas emission in the adjacent coal seam, obtained the basic expression of various gas emission. The pressure relief zone of coal seam overlying strata and the localization of coal seam floor constitute the main area of gas migration and accumulation. As the working face continue to advance, the gas s a flow arch area similar to the fissure arch area. The flow arch area has obvious asymmetry, and it has a higher gas concentration near the working face. ⑥Combined with the actual geological conditions of the No.15-17200 working face, the gas extraction practice carried out by using the combination the pre-pumping and the bottom pumping. On this basis, it proposed to improve the efficiency of gas extraction by using the gas drainage of the ultra-long distance coal seam in the pressure relief of the existing gas tunnel. The coal and gas co-mining efficiency is obvious with significant economic and social value, which provides a new way of 万方数据 英文摘要 V thinking. Key words Raw coal containing gas; Permeability; Damage evolution; Volumetric strain; Quasi-Newton . 万方数据 重庆大学博士学位论文 VI 万方数据 目 录 VII 目 录 中文摘要中文摘要 .......................................................................................................................................... I 英文摘要英文摘要 ....................................................................................................................................... III 1 绪绪 论论 ......................................................................................................................................... 1 1.1 研究背景及意义研究背景及意义 ....................................................................................................................... 1 1.2 国内外研究现状国内外研究现状 ....................................................................................................................... 2 1.2.1 裂隙煤岩体渗流场-应力场耦合研究现状 ...................................................................... 2 1.2.2 裂隙煤岩体损伤演化研究现状 ....................................................................................... 4 1.2.3 覆岩破断及裂隙场分布时空演化规律研究现状 ........................................................... 6 1.2.4 现场卸压瓦斯抽采研究现状 ........................................................................................... 6 1.3 主要研究内容主要研究内容 ........................................................................................................................... 7 1.4 技术路线技术路线 ................................................................................................................................... 8 2 采动影响下工作面矿压显现规律采动影响下工作面矿压显现规律 .............................................................................. 9 2.1 矿井概述及瓦斯赋存规律研究矿井概述及瓦斯赋存规律研究 ............................................................................................... 9 2.1.1 矿井基本概况 ................................................................................................................... 9 2.1.2 工作面概况 ..................................................................................................................... 11 2.1.3 瓦斯赋存规律研究 ......................................................................................................... 11 2.2 工作面前方地应力的现场测试工作面前方地应力的现场测试 ............................................................................................. 12 2.2.1 空心包体应变计 ............................................................................................................. 12 2.2.2 空心包体应变计测量原理 ............................................................................................. 14 2.2.3 地应力现场测试 .............................................................................................................. 15 2.2.4 地应力测试结果分析 ..................................................................................................... 16 2.3 采动影响下工作采动影响下工作面矿压显现规律分析面矿压显现规律分析 ................................................................................. 18 2.4 本章小结本章小结 ................................................................................................................................. 21 3 采动影响下覆岩破断规律研究采动影响下覆岩破断规律研究 ................................................................................. 23 3.1 采动影响下覆岩破断规律相似模型试验采动影响下覆岩破断规律相似模型试验 ............................................................................. 23 3.1.1 相似模型试验的基本原理 ............................................................................................. 23 3.1.2 相似模型试验装置 ......................................................................................................... 24 3.1.3 相似模型试验过程 ......................................................................................................... 28 3.1.4 相似模型试验结果分析 ................................................................................................. 31 3.1.5 采动影响下覆岩破断力学模型 ...................................................................................... 34 3.2 采动影响下覆岩破断规律数值模拟采动影响下覆岩破断规律数值模拟 ..................................................................................... 35 3.2.1 采动影响下覆岩破断数值模拟模型 .............................................................................. 36 万方数据 重庆大学博士学位论文 VIII 3.2.2 采动影响下覆岩破断规律的数值模拟结果分析 ......................................................... 37 3.3 采动影响下覆岩破断规律的现场验证采动影响下覆岩破断规律的现场验证 ................................................................................. 42 3.4 本章小结本章小结 ................................................................................................................................. 45 4 加卸载条件下原煤损伤演化与渗流特性试验研加卸载条件下原煤损伤演化与渗流特性试验研究究 ....................................... 47 4.1 加卸载条件下加卸载条件下原煤三轴渗流试验原煤三轴渗流试验 ......................................................................................... 47 4.1.1 煤样制备 ......................................................................................................................... 47 4.1.2 含瓦斯煤热流固耦合三轴伺服渗流试验装置 ............................................................. 48 4.1.3 加卸载条件下原煤三轴渗流试验过程 ......................................................................... 49 4.2 加卸载条件下原煤三轴渗流试验结果分析加卸载条件下原煤三轴渗流试验结果分析 ......................................................................... 51 4.2.1 加卸载条件下原煤应力-应变曲线变化规律 ................................................................ 52 4.2.2 加卸载条件下原煤体积应变-渗透率曲线变化规律 .................................................... 57 4.2.3 加卸载条件下原煤体积变形-卸围压围压差曲线变化规律 ........................................ 57 4.3 加卸载条件下原煤损伤演化和渗流耦合模型加卸载条件下原煤损伤演化和渗流耦合模型 ..................................................................... 59 4.3.1 基本假设 ......................................................................................................................... 59 4.3.2 原煤损伤演化和瓦斯渗流模型 ..................................................................................... 60 4.3.3 原煤损伤演化和瓦斯渗流模型验证 ............................................................................. 61 4.4 本章小结本章小结 ................................................................................................................................. 64 5 裂隙岩体蠕变裂隙岩体蠕变-损伤损伤-渗流耦合理论渗流耦合理论 ........................................................................ 65 5.1 试验系统的研制试验系统的研制 ..................................................................................................................... 65 5.1.1 实验系统研制的背景及意义 ......................................................................................... 66 5.1.2 实验系统的技术参数 ..................................................................................................... 66 5.1.3 实验系统的结构介绍 ..................................................................................................... 67 5.2 裂隙岩体蠕变裂隙岩体蠕变-损伤损伤-渗流试验渗流试验 .............................................................................................. 70 5.2.1 试件制备 ......................................................................................................................... 70 5.2.2 试验方案及过程 ............................................................................................................. 71 5.3 裂隙岩体蠕变裂隙岩体蠕变-损伤损伤-渗流试验结果分析渗流试验结果分析 .............................................................................. 73 5.3.1 单轴稳定蠕变试验结果分析 ................