岩溶矿区采动裂隙发育及其地表塌陷规律研究.pdf

博士学位论文博士学位论文 岩溶矿区采动裂隙发育及其地表塌陷规律研究岩溶矿区采动裂隙发育及其地表塌陷规律研究 研研 究究 生生周周 泽泽 导导 师师朱川曲朱川曲 教授教授 学学 科科矿业工程矿业工程 研究方向岩石力学与岩层控制研究方向岩石力学与岩层控制 2017 年年 11 月月 密密 级级公开 中图分类号中图分类号TD325 万方数据 A Dissertation ted for the Doctor Degree Study on the development law of mining fracture and karst surface collapse when mining in karst area CandidateZe ZHOU Supervisor and RankProf. Chuanqu-ZHU 万方数据 岩溶矿区采动裂隙发育及其地表塌陷规律研究岩溶矿区采动裂隙发育及其地表塌陷规律研究 学位类学位类型型 学术型学位学术型学位 作者姓名作者姓名 周周 泽泽 作者学号作者学号 140101010001 学科（专业学位类别学科（专业学位类别 矿业工程矿业工程 研究方向（专业领域研究方向（专业领域 岩石力学与岩层控制岩石力学与岩层控制 导 师 姓 名 及 职 称导 师 姓 名 及 职 称 朱川曲朱川曲 教授教授 实 践 导 师 姓 名 及 职 称实 践 导 师 姓 名 及 职 称 所在学院所在学院 资源环境与安全工程学院资源环境与安全工程学院 论文提交日期论文提交日期 2017 年年 11 月月 万方数据 学位论文原创性声明学位论文原创性声明 本人郑重声明 所呈交的论文是本人在导师的指导下独立进行研究所取 得的研究成果。 除了文中特别加以标注引用的内容外， 本论文不包含任何其 他个人或集体已经发表或撰写的成果作品。对本文的研究做出重要贡献的 个人和集体， 均已在文中以明确方式标明。 本人完全意识到本声明的法律后 果由本人承担。 作者签名 日期 年 月 日 学位论文版权使用授权书学位论文版权使用授权书 本学位论文作者完全了解学校有关保留、使用学位论文的规定，同意学 校保留并向国家有关部门或机构送交论文的复印件和电子版，允许论文被 查阅和借阅。本人授权湖南科技大学可以将本学位论文的全部或部分内容 编入有关数据库进行检索， 可以采用影印、 缩印或扫描等复制手段保存和汇 编本学位论文。 涉密论文按学校规定处理。 作者签名 日期 年 月 日 导师签名 日期 年 月 日 万方数据 湖南科技大学博士学位论文 i 摘摘 要要 我国南方存在大面积的岩溶地区煤层开采情况，既有赋存于煤层顶板的长兴灰岩， 也有位于底板的茅口灰岩。底板岩溶水对矿井安全生产构成威胁，而在煤层开采条件下 顶板岩溶裂隙发育容易破坏岩溶地区生态环境。 目前有关岩溶地区煤层开采研究多集中 在岩溶水对矿井安全生产的影响方面。然而，岩溶地区地表生态环境脆弱，煤层开采对 岩溶地区浅表生态环境有着明显影响， 有关顶板赋存岩溶时的煤层采动裂隙发育及其对 浅埋岩溶地表变形的影响方面的研究相对较少。有鉴于此，本文从浅埋岩溶地区生态环 境保护的角度出发，依托国家自然科学基金基于浅表水环境保护的南方岩溶煤矿开采 基础理论研究 （51474104） ，采用理论分析、相似模拟试验以及数值模拟相结合的研究 方法着重对顶板赋存岩溶时的煤层开采工作面矿压显现特征、岩层移动规律、采动裂隙 发育高度以及浅埋岩溶洞地表塌陷进行了深入研究和讨论，主要工作及成果如下 1）采用弹性地基梁理论、塑性铰理论对采场覆岩破断位置以及岩层竖向破断裂隙 扩展进行了分析，通过数值模拟对导水裂隙带的发育规律进行了研究，研究结果表明 导水裂隙带的发育应充分考虑覆岩的结构差异。有鉴于关键层对岩层移动的控制作用， 可采用塑性铰理论对处于断裂带上部的关键层竖向贯通裂隙进行分析， 从而确定其导气 导水能力，进而对其是否为导水裂隙带的上边界进行判断。在采动覆岩断裂以及导水裂 隙发育规律的基础上，结合岩溶洞与开采工作面的相对位置关系，建立了采动作用下岩 溶洞塌陷分析模型。 2）通过岩溶地区煤层开采岩层移动相似模拟试验分析了岩溶洞对采动裂隙发育的 影响，研究结果表明，采动覆岩导水裂隙带中存在岩溶洞时，岩溶洞对采动裂隙的发育 具有一定的导向和吸引作用；由于缺少足够支撑，岩溶洞顶板岩层下沉值在岩溶洞处有 异常增大现象，最终导致采动裂隙发育在岩溶洞顶板处达到最大；在水平方向上，岩溶 洞对采动影响有明显的阻碍作用，当工作面开采只在岩溶洞一侧推进时，采动侧岩层受 采动影响强烈，实体煤帮侧采动岩层受采动影响不明显，靠近采动侧的岩层弯曲下沉值 明显大于靠近实体煤帮侧的岩层弯曲下沉值，致使岩溶洞两帮出现不协调变形。 3）采用离散元数值模拟软件对岩溶地区煤层开采工作面矿压显现特征、采动裂隙 发育规律进行了模拟分析，分析结果表明，岩溶矿区工作面开采过程中来压步距相较于 非岩溶矿区更小，其来压更加频繁；当岩溶洞距离导水裂隙带上边界一定距离时，岩溶 洞隙吸引采动裂隙向岩溶洞发育，且采动裂隙发育高度在岩溶洞顶板正上方容易激增， 并形成“突刺”状。同时，在受到开采影响等强烈的力学扰动条件下，采动岩体裂隙的发 育主要受岩体力学行为的影响，岩溶水对采动裂隙发育影响相对较小。在较强的开采扰 动下，岩溶洞裂隙与采动裂隙扩展造成岩溶水流失速度远远大于岩溶水补给速度；当岩 溶洞处于浅埋状态或水补给少时，开采扰动极易造成岩溶洞内部形成负压，加速岩溶洞 万方数据 摘 要 ii 的塌陷。 4） 当有采动影响和岩溶水压的共同作用时， 岩溶裂隙发育程度更高， 更加容易促使 采动裂隙与岩溶裂隙贯通。 在开采扰动下， 不同的岩溶水压导致不同的岩溶水流失速度， 且存在一定的安全水头值。即当岩溶洞内水压力值小于安全水头值时，岩溶水漏失速度 处于较低水平并较稳定，一旦岩溶洞内水压力值超过安全水头值，岩溶水漏失速度会出 现激增， 影响矿井安全生产以及浅表水生态平衡， 并据此提出了“疏水抗压开采”和“局部 注浆，降压开采”的开采方式。 5）采用数值模拟再现了开采扰动下浅埋岩溶洞塌陷的过程，其过程大致可分为四 个阶段岩溶洞潜伏阶段、岩溶洞裂隙扩展形成开口岩溶洞阶段、土洞发展阶段、岩溶 地面塌陷阶段。对开采扰动下的开口岩溶洞的形成条件、土洞极限发育高度及其影响因 素以及地裂缝的极限发育深度进行了理论分析， 提出开采扰动下浅埋岩溶洞塌陷不发育 至地表的条件是，覆盖层厚度大于土洞极限平衡高度与地裂缝极限发育深度之和。 6） 根据坪湖岩溶矿区覆盖层厚度、 浅埋岩溶洞分布以及工作面的布置方式， 对浅埋 岩溶塌陷倾向较大的区域进行了预判， 与实际生产过程中地表破坏严重的区域较为吻合； 根据实际开采情况并结合论文前文研究成果， 对坪湖矿浅埋岩溶区域下方工作面进行了 优化， 提高了工作面的回采率。 结合以往开采经验， 设计了短壁间隔条带充填开采方案， 解决了坪湖矿岩溶层下方近距离煤层的安全回采问题。 关键词关键词岩溶地区岩溶地区采煤；采煤；采动裂隙；采动裂隙；岩层移动岩层移动；；岩溶洞塌陷岩溶洞塌陷；；绿色开采绿色开采 万方数据 湖南科技大学博士学位论文 i Abstract In the south of China, there exists a large karst area with coal seam mining, there are not only the Changxing limestone that exist in the roof of the coal seam, but the Maokou limestone exist in the floor of coal seam. The karst water existed in the floor poses a threat to the mine safety production, and the karst fissure development can destroy the ecological environment in karst region when coal seam mining. At present, the research on coal seam mining in karst area is focused on the influence of karst water to mine safety production. However, the surface ecological environment of karst area is fragile, and the coal seam mining has obvious influence on the shallow ecological environment of karst area. There are relatively few researches on the development of mining fracture and its influences on the surface deation of shallow buried karst when there are karst caves exiting in the roof of coal seam. In view of this, from the perspective of ecological environmental protection in shallow karst area, this paper based on the national natural science foundation of china-Study on basic theory of coal mining for surface water environment protection in karst region of south China 51474104, by the research of combining theoretical analysis, similar simulation experiment and numerical simulation, the coal mining working face stress features, regularity of strata movement, mining- induced fracture height and shallow buried karst cave surface subsidence mechanism have been studied and discussed, the main works and results are as follows 1 The breaking location and vertical fracture of strata have been analyzed by elastic foundation beam theory and plastic hinge, and the diversion fissure zone development has been studied by numerical simulation. The research results show that, the diversion fissure zone development should consider the structural differences of overburden, and in consideration of the influence of the key strata on strata movement, vertical fracture of key strata located upper part of the fracture zone can be analyzed by plastic hinge theory, thus, the water transmitting ability of the key strata can be determined, then the upper boundary of the diversion fissure zone can be judged. Based on the mining overburden fracture and the development rule of diversion fissure zone, combining the relative location of karst cave and mining working face, the generalization model of karst cave under mining influence was established. 2 By the similar simulation experiment for strata movement when mining in karst region, the influence of karst cave on mining fracture development has analyzed. And the results show that, when there are karst caves in diversion fissure zone, the karst cave has a certain orientation and attraction to the development of mining fracture. For lack of adequate support, the subsidence of caves roof strata has an abnormal increase at the top of cave, which makes the mining fracture developed to the largest at the top of cave. In the horizontal direction, the karst cave has an obvious hindrance to the influence of mining. When the coal mining is only on the side of the cave, the mining side strata are strongly influenced by mining, and the influence is not obvious on the mining strata near integrated coal. The subsidence of mining side strata is 万方数据 Abstract ii significantly larger than the subsidence of the strata neat integrated coal, which result in incongruous deation of the two sides of karst cave. 3 The stress characteristics of working face and the development law of mining fracture when mining in karst area are simulated by discrete element numerical simulation software. And the simulated results show that, Compared with non-karst regions, the periodic caving span of working face in karst area is smaller than that of non-karst region, it is more frequent. When there is a karst cave with a certain distance from the upper boundary of diversion fissure zone, the height of mining fracture above the top of karst cave increase sharply and s a “spike“. And compared with the strong mechanical disturbances such as mining effects, the development of rock fracture is mainly controlled by the mechanics of rock mass, karst water has a relatively small influence on the development of mining fracture. With mining disturbance, karst water loss rate which caused by the development of mining fractures and karst fractures is far greater than that of karst water; when the karst cave is in shallow burial condition or water supply is low, the mining disturbance can cause the negative pressure inside the karst cave and accelerate the collapse of the karst cave. 4 When there is combined action of the mining action and the karst water pressure, the karst fissure is more developed, and it is more likely that the mining fracture and the karst fissure will penetrate. Under the disturbance of mining, different karst water pressure leads to karst water different loss rate. That is when the water pressure value in karst cave is less than the security head value, the karst water leakage rate will at lower levels, once the water pressure value is more than security head value, The leakage rate of karst water will increase sharply, which not only affect the mine safety production, but also the shallow water ecological balance. And accordingly this, the mining of “draining and anti-hydraulic pressure mining” and “local grouting and release water press mining” have been put forward. 5 A numerical simulation is used to reconstruct the collapse of the shallow buried karst cave, the surface subsidence process of shallow buried karst cave can be divided into four stages The latency stage of karst cave, the crack expansion stage of karst cave and s the open karst cave, the development stage of the soil cave, karst ground collapse stage. With the mining disturbance, the ing conditions of the open rock karst caves, the ultimate developmental height of the soil caves and its influence factors, and the extreme development depth of the ground fractures have been analyzed theoretically. It is suggested that if the shallow buried karst caves collapse under the mining disturbance are not developed to the surface, the thickness of the covering layer should be greater than the sum of the ultimate developmental height of the soil caves and the ultimate development depth of the ground crack. 6 According to the thickness of covering layer, the distribution of shallow buried karst cave and the layout of mining working face in PINGHU coal mine, shallow buried karst collapse prone area has been prejudged, which is consistent with the surface damage serious area in the actual production process. Based on the actual mining conditions and combining the research results of the paper, the working face under the shallow buried karst area of PINGHU 万方数据 湖南科技大学博士学位论文 iii coal mine have been optimized, the recovery rate of the working face is improved. Based on the previous mining experience, shortwall stripe-and-pillar mining with backfilling have designed to solve safe coal seam mining which is near the below the karst layer of PINGHU mine. Keywords coal mining in karst area; mining-induced fissure; strata movement; karst cave collapse; green mining 万方数据 湖南科技大学博士学位论文 目目 录录 摘 要 ......................................................................................................................................... i Abstract ....................................................................................................................................... i 第 1 章 绪论 ............................................................................................................................ 1 1.1 研究背景和意义 ....................................................................................................... 1 1.1.1 我国岩溶分布广泛 ........................................................................................ 1 1.1.2 煤层地下开采对环境影响明显 .................................................................... 2 1.1.3 研究意义 ........................................................................................................ 3 1.2 国内外研究现状 ....................................................................................................... 4 1.2.1 岩溶洞塌陷形成机制研究现状 .................................................................... 4 1.2.2 岩溶洞稳定性分析研究现状 ........................................................................ 6 1.2.3 采动岩层移动及采动裂隙发育规律研究现状 ............................................ 8 1.2.4 资源与环境协调（绿色）开采研究现状 .................................................... 9 1.3 主要研究内容和目的 ............................................................................................. 10 1.3.1 主要研究内容 .............................................................................................. 10 1.3.2 研究方法 ...................................................................................................... 11 1.3.3 主要研究目的 .............................................................................................. 12 第 2 章 采动覆岩裂隙发育规律及顶板岩溶洞分析模型 .................................................. 13 2.1 采动覆岩破断特征 ................................................................................................. 13 2.1.1 覆岩初次断裂移动规律分析 ...................................................................... 13 2.1.2 覆岩周期性断裂分析 .................................................................................. 17 2.1.3 随着岩层移动向上发展覆岩断裂分析 ...................................................... 19 2.2 导水裂隙带发育高度分析 ..................................................................................... 20 2.2.1 导水裂隙带岩层移动特征 .......................................................................... 20 2.2.2 导水裂隙带发育数值分析 .......................................................................... 24 2.3 采动作用下顶板岩溶塌陷分析模型 ..................................................................... 28 2.3.1 煤层顶板岩溶洞隙及岩溶水赋存特征 ...................................................... 28 2.3.2 岩溶塌陷影响因素 ...................................................................................... 29 2.3.3 采动作用对顶板岩溶塌陷的影响 .............................................................. 30 2.3.4 采动作用下顶板岩溶塌陷分析模型的建立 .............................................. 31 2.4 本章小结 ................................................................................................................. 33 第 3 章 岩溶矿区覆岩移动及岩溶裂隙发育相似模拟试验 .............................................. 35 万方数据 目 录 3.1 相似模拟试验相似理论 ......................................................................................... 35 3.1.1 相似三定律 .................................................................................................. 35 3.1.2 相似关系 ...................................................................................................... 36 3.2 试验研究主要内容及其设计 ................................................................................. 37 3.2.1 试验研究主要内容 ...................................................................................... 37 3.2.2 试验方案设计 .............................................................................................. 37 3.3 开采扰动作用下岩溶洞破坏特征 ......................................................................... 40 3.3.1 开采扰动作用下顶板圆形岩溶洞破坏特征 .............................................. 40 3.3.2 开采扰动作用下顶板矩形岩溶洞破坏特征 .............................................. 43 3.4 岩溶矿区岩层移动特征 ......................................................................................... 45 3.4.1 工作面推进岩溶洞下方时采动岩层移动规律 .......................................... 45 3.4.2 工作面推进完成时岩层移动规律 .....................