大倾角煤层长壁开采围岩应力演化及结构稳定性研究.pdf

Research on Evolution of Stress and Structural Stability of Surrounding Rock in the Longwall Mining of Steeply Dipping Seam Dissertation ted to Xi’an University of Science and Technology In Partial Fulfillment of the Requirement For the Degree of Doctor of Engineering By Wang Hong-wei School of Energy Engineering Dissertation Directed by Professor Wu Yong-ping Oct. 2014 万方数据 论文题目大倾角煤层长壁开采围岩应力演化及结构稳定性研究 专 业采矿工程 博 士 生王红伟 （签名） 指导教师伍永平 （签名） 摘 要 大倾角煤层长壁开采过程中采场围岩“关键域”的非确定性和“岩体结构”的“变 异”是形成这类煤层开采岩层运动异常复杂且难以控制的关键。研究大倾角煤层长壁开 采覆岩应力场形成及演化、岩体结构稳定性，奠定大倾角煤层安全高效开采理论基础， 对丰富复杂埋藏条件煤层开采理论与技术具有重要意义。 本文采用物理相似模拟实验、数值分析、理论分析、工程实践等相结合的综合研究 方法，对大倾角煤层长壁采场覆岩运动破坏规律、应力场形成与演化特征、围岩“关键 域”转化与岩体结构稳定性进行的系统研究表明 大倾角煤层开采过程中，沿工作面走向顶板运移具有时序性、不均衡性，工作面上 部区域顶板最先发生垮落， 垮落步距最小， 下部区域顶板最后发生垮落， 垮落步距最大； 沿工作面倾向顶板岩梁中上部位置首先出现离层、破坏，导致顶板垮落形态向上部区域 偏移，呈现出非对称拱形特征，垮落矸石沿工作面倾向滑移充填采空区，呈现下部充填 压实、中部完全充填、上部部分充填的分区特征。 大倾角煤层开采围岩应力重新分布，沿煤层走向呈对称拱形特征，沿煤层倾向呈非 对称拱形特征，且受煤层倾角、采高等因素影响明显。在采场四周煤岩体中形成支承压 力，且支承压力分布形式、大小、峰值点距煤壁距离等具有分区特性。应力分布沿煤层 走向和倾向的叠加，形成大倾角煤层开采采场围岩空间应力拱壳。随着工作面推进，应 力拱壳不断向采场四周煤岩体、上位岩层扩展，非对称特性显现程度增加。 大倾角煤层开采覆岩在“应力-冒落”双拱作用下垮落形成非对称“拱壳”形态，“拱壳” 区域岩层对覆岩活动起决定作用，称为覆岩“关键域”。沿工作面倾斜方向“关键域”转 换导致形成层位不同，下部“关键域”向直接顶和伪顶岩层转移，关键岩块以直接垮落方 式运移；中部“关键域”处于基本顶中下位岩层中，关键岩块运移方式为一次回转垮落； 上部“关键域”向基本顶上位岩层中转移，关键岩块运移方式为二次回转垮落。沿工作面 倾斜方向“关键域”关键岩块相互作用， 形成倾向“梯阶”结构。 不同区域不同位置“关键域” 关键岩块的破坏失稳，引起覆岩空间“拱壳”结构动力失稳， “拱壳”结构失稳分为工作 面上部区域壳基位置、壳肩位置、壳顶位置，工作面中部区域壳基位置、壳肩位置，工 万方数据 作面下部区域壳基位置等六个区域， “关键域”岩体结构变异导致工作面上部区域出现 的高位失稳产生冲击性来压，工作面中下部区域低位失稳出现推垮型事故。 针对枣泉煤矿 120210 大倾角工作面综放开采条件，分析采场“关键域”岩体结构 失稳机制，建立以“支护系统工作阻力分区域控制技术、顶煤放出量分区域控制技术、 工作面倾斜全长与区域分割相结合的全方位立体防护体系”为核心的围岩控制技术体 系，有效控制了采场围岩岩体结构失稳，取得了良好技术经济与社会效益。 关 键 词大倾角煤层；三维模拟实验；应力拱壳； “关键域”转换；倾向“梯阶” 结构；失稳机制 研究类型应用基础研究 万方数据 万方数据 Subject Research on Evolution of Stress and Structural Stability of Surrounding Rock in the Longwall Mining of Steeply Dipping Seam Specialty Mining Engineering Name Wang Hongwei Signature Instructor Wu Yongping Signature ABSTRACT In the process of mining steeply dipping seam, the non-definiteness of critical zone and variation of rock structure within the stope easily result in extremely complex strata movement which is hard to control. Researches on the ation and evolution characteristics of rock-mass stress field and structural stability of rock mass are theoretical foundations for safe and efficient mining and have significance to enrich mining theory and technology in such a complex condition. With a hybrid ology including physical simulation, numerical simulation, theory analysis and in-situ application, the overburden movement and destruction mechanism, ation and evolution mechanism of rock stress field, the critical zone conversion characteristics and the rock structure stability have been done systematically. The researches indicate that In the mining process of steeply dipping seam, roof movement has timing sequence and malconation along the trend, the roof caving occurred first in upper area of stope with smallest caving pace, then in middle area with smaller caving pace, and last in lower area with lagest caving pace. In the tendency of coal seam, separation occurs first and then tensile failure generates at the upper position two-thirds of roof beams, resulting in an upper region offset of roof caving and an asymmetric arch, the gangue slip and filled the gob with partition feature along tendency, including compaction zone in lower areas, completely filled zone in central areas, and partially filled zone in top areas. The surrounding rock stress is redistributed in mining the steeply dipping seam. Distribution of surrounding rock stress presents symmetrical arch characteristics along the trend of coal seam and presents symmetrical arch characteristics along the tendency of coal 万方数据 seam. It is influenced significantly by dip angle and mining height of coal seam. The abutment pressure is ed in the coal-rock mass within the stope with partition feature of distribution mode, peak, and distance and so on. The three-dimensional stress arch-shell in the steeply dipping seam mining is ed by the overlay of stress distribution along the trend and tendency of coal seam. With the working face advancing, it shifts to surrounding rock gradually and the asymmetry characteristics become more apparent. Under action of stress and caving arch in mining the steeply dipping seam, asymmetry arch shell is ed when overburden rock mass are falling. The region of arch shell called critical zone plays a decisive role on the activities of overlying rock. In tendency, critical zone would shift towards immediate roof at lower zone of the stope, and lie in lower part of main roof at middle area of the stope, and would transmit to upper part of main roof at top area of the stope. The scalar structure in tendency direction is ed by the interaction with key rocks. The instability of key rock at critical zone in different area causes dynamic instability of arch shell structure. There are six key parts of arch shell instability, including shell base, shell shoulder and shell roof in top area, shell base and shell shoulder in central area, and shell base in lower area. For the evolution of rock structure of critical zone, senior rock structure leads to impact roof weighting and lower rock structure destabilization leads to roof pushing-collapsing accident. According to conditions of No.120210 fully-mechanized sub level caving face in Zaoquan coal mine, the instability mechanism of rock mass structure is studied. The rock control technology has been established with the core technology of regional control of support loading along the tendency, regional control of top coal caving amount and well-structured safety protection system. The structural instability of surrounding rock in the stope has been controlled effectively. Beneficial technical and economic application is realized. Key words Steeply dipping seam Three-dimensional simulation Stress arch-shell Critical zone conversion calar structure in tendency of coal seam Instability mechanism Thesis Basic application research 万方数据 目 录 I 目 录 主要符号注释表主要符号注释表 ......................................................................................................................... I 1 绪论绪论 ......................................................................................................................................... 1 1.1 选题背景及研究意义 ..................................................................................................... 1 1.1.1 选题背景 .................................................................................................................... 1 1.1.2 研究意义 .................................................................................................................... 1 1.2 国内外研究现状 ............................................................................................................. 2 1.2.1 国内外大倾角煤层开采方法的发展现状 ............................................................... 2 1.2.2 国内外大倾角煤层开采围岩控制理论研究现状 ................................................... 5 1.2.3 国内外大倾角煤层开采研究特点 ......................................................................... 10 1.3 研究内容 ....................................................................................................................... 11 1.4 研究方法和技术路线 .................................................................................................... 12 1.4.1 研究方法 ................................................................................................................. 12 1.4.2 技术路线 ................................................................................................................. 13 2 大倾角煤层开采覆岩空间运移破坏规律 .......................................................................... 14 2.1 概述 ............................................................................................................................... 14 2.1.1 研究方法确定 ......................................................................................................... 14 2.1.2 工程地质和开采条件 .............................................................................................. 14 2.2 大倾角煤层开采覆岩运移垮落规律 ........................................................................... 16 2.2.1 沿工作面走向覆岩运移垮落规律 ......................................................................... 16 2.2.2 沿工作面倾向覆岩运移垮落规律 ......................................................................... 23 2.2.3 覆岩空间运移垮落规律 ......................................................................................... 28 2.3 大倾角煤层开采覆岩垮落机理 ................................................................................... 36 2.3.1 覆岩走向运移垮落力学过程 .................................................................................. 36 2.3.2 覆岩倾向运移垮落力学过程 .................................................................................. 41 2.4 大倾角煤层开采覆岩垮落充填特征 ........................................................................... 42 2.4.1 工作面下部充填压实区 ......................................................................................... 43 2.4.2 工作面上部部分充填区 ......................................................................................... 44 2.5 本章小结 ....................................................................................................................... 46 3 大倾角煤层开采覆岩应力场形成及演化特征 .................................................................. 48 3.1 大倾角煤层开采覆岩应力迁移特征 ........................................................................... 48 3.1.1 数值计算模型建立 ................................................................................................. 48 万方数据 目 录 II 3.1.2 不同采高条件下采场应力形成及演化特征 ......................................................... 49 3.1.3 不同倾角条件下采场应力形成及演化特征 ......................................................... 55 3.1.4 采场应力场形成特征 ............................................................................................. 58 3.2 采场围岩支承压力分布特征 ........................................................................................ 60 3.2.1 采场前后方煤岩体支承压力 ................................................................................. 60 3.2.2 回采巷道两侧煤岩体支承压力 ............................................................................. 61 3.2.3 采场四周煤岩体支承压力分布类型及特征 ......................................................... 64 3.3 围岩三维应力场形成特征 ........................................................................................... 67 3.4 应力拱壳分析模型和形态方程 ................................................................................... 68 3.4.1 应力拱壳分析模型建立 ......................................................................................... 68 3.4.2 应力拱壳形态方程 ................................................................................................. 69 3.5 应力拱壳演化特征 ....................................................................................................... 71 3.6 本章小结 ....................................................................................................................... 74 4 大倾角采场覆岩“关键域”岩体结构稳定性分析 .............................................................. 76 4.1 应力拱壳作用下“关键域”转化特征 ............................................................................ 76 4.1.1 覆岩“应力-冒落”双拱特性 .................................................................................... 76 4.1.2 “关键域”形成层位 .................................................................................................. 77 4.1.3 “关键域”岩体结构破断运移和平衡机制 .............................................................. 79 4.2 大倾角煤层开采岩体结构稳定性分析 ....................................................................... 82 4.2.1 倾向“梯阶”结构形成特征 ..................................................................................... 82 4.2.2 倾向“梯阶”结构力学模型 ..................................................................................... 83 4.2.3 倾向“梯阶”结构稳定性分析 ................................................................................. 84 4.3 大倾角煤层开采“关键域”岩体结构失稳机制 ............................................................ 92 4.3.1 “关键域”岩体结构破坏准则 .................................................................................. 92 4.3.2 “关键域”岩体结构失稳模式 .................................................................................. 93 4.4 大倾角煤层开采“关键域”岩体结构变异致灾机理 .................................................... 94 4.5 本章小结 ....................................................................................................................... 95 5 大倾角煤层开采岩体结构稳定性控制工程实例 .............................................................. 97 5.1 大倾角综放采场“关键域”岩体结构稳定性分析 ........................................................ 97 5.1.1 工程背景 ................................................................................................................. 97 5.1.2 综放采场岩体结构失稳分析 ................................................................................. 99 5.1.3 岩体结构失稳的现场验证 ................................................................................... 100 5.2 大倾角综放采场岩体结构控制技术 ......................................................................... 105 5.2.1 大倾角综放采场围岩控制技术体系 ................................................................... 105 万方数据 目 录 III 5.2.2 顶煤放出量的区域控制 ....................................................................................... 106 5.2.3 支护系统载荷分区域控制 ................................................................................... 106 5.2.4 工作面安全防护 ................................................................................................... 107 5.3 大倾角综放采场围岩控制效果 ................................................................................. 110 5.4 本章小结 ..................................................................................................................... 110 6 结论 .................................................................................................................................... 112 6.1 主要结论 ..................................................................................................................... 112 6.2 创新点 ......................................................................................................................... 113 6.3 展望 ............................................................................................................................. 113 致 谢 .................................................................................................................................... 114 参考文献 ................................................................................................................................ 115 附 录 .................................................................................................................................... 125 万方数据 万方数据 目 录 I C