缓倾斜中厚煤层采动应力场时空演化及覆岩破裂规律.pdf

缓倾斜中厚煤层采动应力场时空演化及 覆岩破裂规律 重庆大学硕士学位论文 学术学位 学生姓名代 沛 指导教师张东明 教授 专 业采矿工程 学科门类工 学 重庆大学资源及环境科学学院 二 O 一五年四月 Space-time Evolution of Mining Pressure Field in Gently Inclined Medium-thickness Seam and Overburden Rupture Rule A Thesis ted to Chongqing University in Partial Fulfillment of the Requirement for the Master’s Degree of Engineering By Dai Pei Supervised by Prof. Zhang Dongming Specialty Mining Engineering College of Resources and Environmental Science of Chongqing University, Chongqing, China April,2015 中文摘要 I 摘 要 进入 21 世纪，随着我国新一轮经济结构的布局与发展，煤炭资源在国民经济 中依旧占有较高的比重。其中煤矿开采中的地层应力变化及安全开采已越来越受 到人们的关注。煤矿开采过程中，巷道的掘进及工作面的回采，都会使得煤层围 岩应力场重新分布。采场围岩的应力受采动影响，原有应力平衡被破坏，巷道围 岩的结构及承载能力受到一定的影响，某些应力集中区还会造成围岩的变形失稳、 甚至出现煤岩体的破碎、岩爆及突出，直接影响煤炭的正常生产。因此，采动应 力场的监测、控制及研究，逐渐成为与煤炭开采并存的问题之一，受到人们的普 遍关注。本文以川煤集团白皎煤矿为背景，研究了该矿缓倾斜煤层开采过程中回 采巷道围岩应力场的时空演化规律，并对覆岩破裂规律进行了分析，为工作面的 安全高效开采提供了一定的理论依据和技术支持。 本文运用有限差分软件 FLAC3D，对缓倾斜中厚煤层的开采过程进行模拟， 分析了不同采距下采场围岩的应力位移变化，研究了采动应力场的时空演化规律 深入探讨了覆岩破断移动变形规律。论文的主要工作和取得的研究成果如下 ①在前人研究成果的基础上，从理论上对缓倾斜中厚煤层开采后的煤岩体应 力、垮落形态、破坏裂隙扩展等机理进行分析。并系统研究了采场覆岩“三带” 的分布及影响高度、范围的确定；分析了覆岩破断的应力学模型；对裂隙场的空 间形态进行理论描述。 ②将现场钻取的岩石样本进行加工，制作成实验室标准试件，通过岩石力学 性质试验得到试件的一般抗压强度为 39.13MPa；通过 Mohr 极限应力圆理论及岩 石破断角 θ 计算得出三组试件的参数黏聚力 c，取平均值为 7.95MPa。结合室内物 理力学性质试验及白皎矿地质情况得出煤系地层的物理力学特性，为数值模拟提 供材料参数支持。 ③运用有限差分软件 FLAC3D 对缓斜中厚煤层开采进行数值模拟， 结果表明 应力场受采动影响而变化，采面推进 50m 时，上山保护煤柱附近围岩最大垂向应 力达到 50.33MPa；回采 150m 时垂向应力增大为 66.58MPa，与采面未开挖前初始 应力 18.24MPa 比较，增大了 48.34MPa，顶板最大下沉量达 20.30cm。该处现场实 测最大位移下沉量为 24.80cm，模拟结果与现场测量值较吻合。 ④对围岩应力现场监测数据和数值模拟结果进行对比分析，随着工作面的推 进，对固定监测点的影响越来越明显，垂直应力逐渐变大、且应力变化速率随开 挖距离的接近而逐渐加快；顶板覆岩及底板岩层的移动变形逐渐增大。 关键词关键词缓倾斜，中厚煤层，采动应力场，FLAC3D 数值模拟 重庆大学硕士学位论文 II 英文摘要 III ABSTRACT In 21TH century,with the rapid development of China economy and technology,the development and using of coal resources is becoming more and more important in national economy.Where ation stress and safety mining during mining arise peoples concerns.In the procession of colliery exploitation,along with the tunnel drilling and face mining,stress field of surrounding rock will be redistributed.The change of stress in infection zones of coal mining,especially the redistribution of stress of rock mass will impact on the integrity and stability of the surrounding rock of roadway,even result in instability and destruction of surrounding rock,arise coal crushing in high stress area and coal and gas outburst,affect the production of coal directly.Therefore,the monitoring,control and research of mining pressure field gradually are becoming one of the problems as important as coal mining,getting the attention of people.Based on actual situation of Baijiao mine,studied the space-time evolution regularities of surrounding rock pressure field in mining gateway in gently inclined coal seams,and the broken variation of overburden.It has provided technological and theoretical basis support for safe and efficient mining of working face. Simulated variation of surrounding rock pressure with different distance in mining gently inclined medium-thickness seam,in-depth study evolution laws of overburden ruptured and the space-time evolution regularities of mining pressure field based on finite difference softwares Flac3D in this paper.Here are some preliminary conclusions ①Theoretically analysis coal and rock mass stress,caving and the extension of destroy crack in mining gently inclined medium-thickness seam;system discussed the divide of “Three Zones“ in overburden failure and confirmed its scope of influence;analysed mechanical model of overburden strata destruction and described the space of fracture field based on the results of previous studies. ②Process the rock sample into standard specimen in lab.The general compressive strength of samples proved as 39.13MPa by rock mechanical properties tests;calculate the cohesion of c by Mohr stress circle theory and rock rupture angle θ; where the general cohesion of c of three groups specimens is 7.95MPa.In combination with mechanical property test and engineering geological conditions obtained the physical and mechanical properties of coal measure strata;supporting material parameters for 重庆大学硕士学位论文 IV numerical simulation. ③ Used finite difference software Flac3D simulated gently inclined medium-thickness seam mining.Results show thatthe stress field influenced by mining and the max vertical stress of surrounding rock nearby uphill pillar is 50.33MPa when the working face promoted 50m,while the stress increased to 66.58MPa when promoted 150m,it has increased 48.34MPa than initial stress which was 18.24MPa before mining.At the same time,the max roof sinkage is 20.30cm where the field measurement is 24.80cm.The simulation results agree well with field measurement level. ④The comparison between model calculated results and field monitoring data of surrounding rock stress showed that the status of monitoring points influenced by stress change more and more significantly with the working face advanced,vertical stress increased gradually even the rate of change gradually deepens with working face comes near.Also the changes of roof displacement is effected by mining stronger and stronger. KeywordsGently inclined,Medium-thickness seam,Mining pressure field,Flac3D Numerical simulation 目 录 V 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 选题依据及研究意义选题依据及研究意义 ........................................................................................................... 1 1.1.1 选题依据 .................................................................................................................... 1 1.1.2 研究意义 .................................................................................................................... 2 1.2 国内外研究历史及现状国内外研究历史及现状 ....................................................................................................... 2 1.2.1 煤层采动应力场及覆岩破坏机理研究现状 ............................................................ 2 1.2.2 煤层覆岩移动破断机理研究现状 ............................................................................ 4 1.2.3 围岩应力场及覆岩破裂数值模拟研究现状 ............................................................ 4 1.2.4 采动覆岩破裂规律研究现状 .................................................................................... 5 1.3 已有研究的不足已有研究的不足 ................................................................................................................... 7 1.4 论文研究的理论和实际意义论文研究的理论和实际意义 ............................................................................................... 7 1.5 本文的研究内容及方法本文的研究内容及方法 ....................................................................................................... 8 1.5.1 本文的主要研究内容 ................................................................................................ 8 1.5.2 研究方法及技术路线 ................................................................................................ 9 2 缓倾斜缓倾斜中厚中厚煤层开采采动应力场实验研究煤层开采采动应力场实验研究 ....................................................... 11 2.1 实验矿井概况实验矿井概况 ..................................................................................................................... 11 2.1.1 白皎煤矿基本情况 .................................................................................................. 11 2.1.2 地质条件情况 .......................................................................................................... 13 2.1.3 开采煤层情况 .......................................................................................................... 13 2.2 试验场地选取、方案确定试验场地选取、方案确定 ................................................................................................. 15 2.2.1 试验场地选取 .......................................................................................................... 15 2.2.2 试验技术方案 .......................................................................................................... 16 2.3 数据的采集与处理数据的采集与处理 ............................................................................................................. 21 2.3.1 围岩应力 .................................................................................................................. 21 2.3.2 顶板下沉量 .............................................................................................................. 22 3 缓倾斜煤层开采围岩体缓倾斜煤层开采围岩体基本基本力学力学特性特性试验试验 ....................................................... 25 3.1 岩土体力学模型岩土体力学模型 ................................................................................................................. 25 3.1.1 岩体加卸载准则 ...................................................................................................... 25 3.1.2 岩体的弹塑性屈服准则 .......................................................................................... 27 3.2 试验仪器及试验方案试验仪器及试验方案 ......................................................................................................... 28 重庆大学硕士学位论文 VI 3.3 试验结果及分析试验结果及分析 ................................................................................................................. 30 4 缓倾斜煤层采动应力场演化规律数值模拟缓倾斜煤层采动应力场演化规律数值模拟....................................................... 33 4.1 数值模拟方法及原理数值模拟方法及原理 ......................................................................................................... 33 4.1.1 有限差分概念及原理 .............................................................................................. 33 4.1.2 有限差分基本算法 ................................................................................................... 33 4.2 数值模拟软件介绍数值模拟软件介绍 ............................................................................................................. 35 4.2.1 数值软件分析的特点 .............................................................................................. 35 4.2.2 FLAC3D 软件分析原理 ........................................................................................... 35 4.3 数值计算模型的建立数值计算模型的建立 ......................................................................................................... 38 4.3.1 煤岩层力学参数 ...................................................................................................... 38 4.3.2 计算模型的建立 ...................................................................................................... 39 4.4 数值模拟结果分析数值模拟结果分析 ............................................................................................................. 40 4.4.1 采动应力演化规律 .................................................................................................. 41 4.4.2 采动变形曲线分析 .................................................................................................. 44 4.5 数值模拟与实测值比较数值模拟与实测值比较 ..................................................................................................... 46 4.6 本章小结本章小结 ............................................................................................................................. 46 5 缓倾斜煤层采动裂隙分布规律研究缓倾斜煤层采动裂隙分布规律研究 ...................................................................... 49 5.1 煤层采动裂隙分布规律煤层采动裂隙分布规律 ..................................................................................................... 49 5.1.1 煤层采动裂隙场移动分带 ...................................................................................... 49 5.1.2 采动覆岩移动分区 .................................................................................................. 50 5.2 采动裂隙演化数值模拟采动裂隙演化数值模拟 ..................................................................................................... 52 5.2.1 采动裂隙演化规律 .................................................................................................. 52 5.2.2 采场围岩“o-x”区域演化 ......................................................................................... 56 5.2.3 采动覆岩移动规律 .................................................................................................. 59 5.3 采动变形曲线分析采动变形曲线分析 ............................................................................................................. 61 6 采动覆岩应力场裂隙场采动覆岩应力场裂隙场耦合关系耦合关系 ............................................................................ 63 6.1 引言引言 ..................................................................................................................................... 63 6.2 煤层采动应力场的分布及特点煤层采动应力场的分布及特点 ......................................................................................... 63 6.3 覆岩移动及破坏的力学模式覆岩移动及破坏的力学模式 ............................................................................................. 65 6.4 采动裂隙场的空间形态采动裂隙场的空间形态 ..................................................................................................... 66 6.5 本章小结本章小结 ............................................................................................................................. 69 7 结论及展望结论及展望 ............................................................................................................................ 71 7.1 结论结论 ..................................................................................................................................... 71 7.2 展望展望 ..................................................................................................................................... 72 目 录 VII 致致 谢谢 ............................................................................................................................................ 75 参考文献参考文献 ....................................................................................................................................... 77 附附 录录 ............................................................................................................................................ 83 A.作者在攻读学位期间发表的论文目录作者在攻读学位期间发表的论文目录 ............................................................................ 83 B.作者在攻读学位期间参加的科研项目情况作者在攻读学位期间参加的科研项目情况 .................................................................... 83 重庆大学硕士学位论文 VIII 1 绪 论 1 1 绪 论 在煤矿安全开采领域的诸多研究中，矿山压力一直是学者们研究的重点，取 得了一定的研究成果。其中，原岩应力以及煤层开采所造成的矿场压力改变、应 力重新分布与集中、围岩变形破断等方面，受到人们的普遍关注。近年来,煤矿开 采深度不断增加,强度也不断增大,随之煤层所处的地层压力也逐渐增大,煤层赋 存条件不断恶化导致煤岩动力灾害频发。由于采动应力场的改变与破坏，引起采 场应力的重新分布、围岩应力集中、采掘巷道的变形破坏，甚至引起煤岩涌出或 突出危险，严重影响井下人员的生命安全。因此，研究煤层采动条件下覆岩破坏 移动规律,分析煤岩层裂隙破断条件、移动分层及演化规律,进而对采动应力场时 空演化规律进行研究，指导巷道加固及工程施工，防止矿压灾害的发生。 1.1 选题依据及研究意义 1.1.1 选题依据 长期以来,煤炭在我国国民经济的一次能源消费结构中始终占有绝对比重,是 国家能源安全的重要保证。由于煤炭是不可再生资源,因此,必须尽可能合理地开 采地下煤炭资源,确保煤炭工业持续、稳定、健康地发展,以满足国家经济和人民 生活日益增长的需求。 地应力是地下工程稳定性的重要影响因素,是工程地质学长期研究的主要课 题之一。原岩应力中包括了自重应力与构造应力，一般认为岩层所受到的应力与 其埋深成一定的正比关系，应力分布通常不均匀。在地质构造复杂地区，地层最 大主应力受各种因素作用而不断变化。 矿井采掘