采动岩层与地表移动的“四带”模型研究.pdf
论文题目采动岩层与地表移动的“四带”模型研究 专 业矿业工程 博 士 生夏小刚邵小平 (签名) 指导教师黄庆享石平五 (签名) 摘 要 开采引起的采动损害与环境问题日益突出,煤矿“绿色开采”已成为科学采矿发展 的方向。掌握开采引起的岩层与地表移动的数学规律和力学机理,建立“岩层垮落岩 层移动变形地表沉陷”一体化的岩层和地表移动的数学力学模型,实现岩层与地表移 动的整体预计,对丰富开采沉陷控制理论、促进开采沉陷实践具有重要的意义。 本文采用理论分析、数学建模、相似模拟和实测验证等手段,对水平、近水平煤层 开采条件下,采动岩层与地表移动的数学力学模型进行了系统的研究。 通过总结岩层与地表移动的特征、规律以及二者之间的关系,基于“岩层垮落岩 层移动变形地表沉陷”一体化的研究思路,对各岩层移动带的特征进行了描述,将裂 隙带划分为“似连续带”和“块体铰接带” ,提出了岩层移动的“冒落带、块体铰接带、 似连续带、弯曲下沉带”四带划分,给出了各移动带之间的岩移传递条件及各带高度的 确定方法,建立了岩层与地表移动的总体框架模型。 基于冒落带形成过程,考虑冒落带岩石碎胀系数的时间效应和岩石散体空隙率,采 用分形几何方法对冒落带高度的动态变化进行了描述。针对块体铰接带岩层的非连续特 征和块体铰接特性,采用 DDA 法建立块体铰接带岩层移动的数学力学模型,并给出了具 体计算流程。考虑裂隙发育对岩石单轴抗压强度的影响以及岩石弹性模量与单轴抗压强 度的关系,推导出了弹性模量与裂隙发育之间分形几何关系,建立似连续带岩层的弹性 薄板移动模型。对弯曲下沉带,考虑关键层效应,提出弯曲下沉带内单一岩层下沉移动 的椭球台模型及其各岩层移动的叠加准则,建立了弯曲下沉带岩层及覆岩整体移动的数 学模型,推导出了不同开挖空间的地表沉陷的预计公式。 最后,通过工程实例对所建模型进行论证,证明所建模型的合理性和有效性。 关 键 词煤炭开采;岩层与地表移动; “四带” ;数学模型 研究类型应用研究 Subject Study on “Four-zone” Models of Mining Strata and Surface Movement Specialty Mining Engineering Name Xia Xiaogang ao Xiao Signature Instructor Huang Qingxiang Si Pingwu Signature ABSTRACT The mining damage and environmental problems caused by traditional mining mode have become increasingly prominent. “Green Mining” of coal has become the direction of science mining. Mastering the mathematical laws and mechanical mechanism of strata and surface movement caused by coal mining, establishing the mathematic and mathancis model of strata and surface movement based on“Strata CollapseStrata Movement and Deation Surface Subsidence”, bringing about the overall prediction of strata and surface movement which have very important significance of enriching the control theory and promoting practice of mining subsidence. In this paper, through the theoretical analysis, mathematical model, similar simulation verification by measurement and other means, the mathematic and mechanic model of mining strata and surface movement has been systematicly studied under level and nearly level coal mining condition. By summarizing the characteristics、laws and the relationship between strata and surface movement.Based on the integerated process of “Stratum CollapseStratum Movement and DeationSurface Subsidence”, the characteristic of each stratum movement zone has been described. In the same time, the fracture zone is divided into “Quasicontinuous Zone” and “Block Articulated Zone”, so the four zones division of “Caved zone、Quasicontinuous Zone、 Block Articulated Zone、 Continuous Deation Zone”has been putted forward. Also the strata movement transferration condition and the height determination of each zone have been given. At last, the overall framework model of strata and surface movement also is put forward. Based on the ation process of caved zone.Considerring the time effect of rock swell coefficient and rock void content of caved zone strata, the dymanic change of caved zone height has been discribed by fractal geometry. In connection with the non-continuous feature and the blocks articulated characteristics, the mathematic and mechanic model of block articulated zone movement has been built up by the discontinuous deation analysis theory DDA, the specific calculation process also has been given. Considering the influence of fissures on the uniaxial compressive strength 、the relationship between the rock elastic modulus and the uniaxial compressive strength. The fractal geometry relationship between elastic modulus and fracture has been deduced, the elastic plate movement model of quasicontinuous zone has also been established. As far as continuous deation zone is concerned, considering the key strata effect, the elliptical table model of single stratum deation in continuous deation zone and the superposition criterion of strata deation have been putt forward. The movement deation models of continuous deation zone and the whole overburden strata have also been established. The prediction ulae of different excavation space have also been derived. Finally, through engineering examples to demonstrate the model, the rationality and effectiveness of the model has been proved. Key words Coal mining Strata and surface movement “Four-Zone” Mathematical models Thesis Application Research 目 录 I 目 录 1 绪论 ...................................................................................................................................1 1.1 选题背景与研究意义..................................................................................................1 1.1.1 选题背景..........................................................................................................1 1.1.2 选题意义..........................................................................................................2 1.2 文献综述 .....................................................................................................................3 1.2.1 开采沉陷理论的研究综述...............................................................................3 1.2.2 岩层与地表移动规律的(实测)研究综述....................................................5 1.2.3 岩层与地表移动预计理论及方法的研究综述 ................................................6 1.2.4 采动岩层移动与控制的研究综述....................................................................9 1.2.5 开采沉陷预计模型的研究综述 .....................................................................10 1.2.6 影响采动岩层与地表移动因素的研究综述..................................................12 1.2.7 存在的问题及不足.........................................................................................12 1.3 主要研究内容及技术路线 ........................................................................................13 1.4 本章小结 ...................................................................................................................14 2 采空区上覆岩层的“四带”特征及其划分....................................................................15 2.1 岩层与地表移动的基本规律与特征.........................................................................15 2.1.1 岩层与地表移动的基本过程.........................................................................15 2.1.2 岩层移动的基本规律及特征.........................................................................16 2.1.3 地表移动的基本规律及特征.........................................................................19 2.1.4 岩层与地表移动的关系.................................................................................22 2.2 采空区上覆岩层的“四带”特征.................................................................................23 2.2.1 采空区上覆岩层的“四带”特征......................................................................23 2.2.2 “四带”定义描述及各带岩层的特征...............................................................24 2.2.3 浅埋煤层上覆岩层分带的讨论 .....................................................................26 西安科技大学博士学位论文 II 2.3 “四带”划分准则的建立..............................................................................................27 2.3.1 移动分带划分的区域准则.............................................................................28 2.3.2 基于分形的移动分带划分的应力准则..........................................................29 2.4 分带岩移传递准则的建立 ........................................................................................33 2.4.1 基于介质特性、破坏形式的分带岩移传递准则...........................................33 2.4.2 基于弯曲条块长度的分带岩移转化准则......................................................34 2.5 “四带”岩层位置的确定..............................................................................................36 2.5.1 弯曲下沉带高度确定.....................................................................................36 2.5.2 冒落带高度的确定.........................................................................................39 2.5.3 似连续带和块体铰接带高度的确定..............................................................40 2.6 岩层与地表移动总体框架模型的提出.....................................................................40 2.7 工程应用 ....................................................................................................................40 2.8 本章小结 ...................................................................................................................43 3 冒落带动态高度及对岩层移动的影响 ...........................................................................45 3.1 冒落带移动分析........................................................................................................45 3.1.1 冒落带形成的阶段划分.................................................................................45 3.1.2 冒落过程各阶段的转化判据.........................................................................46 3.1.3 冒落带形成分析.............................................................................................47 3.2 冒落带的动态高度....................................................................................................48 3.2.1 碎胀系数对冒落带高度的影响分析..............................................................48 3.2.2 空隙率对碎胀系数影响分析.........................................................................49 3.2.3 基于孔隙率残余碎胀系数确定 .....................................................................54 3.2.4 冒落带最终冒落高度的确定.........................................................................54 3.3 工程应用 ...................................................................................................................55 3.4 本章小结 ...................................................................................................................56 4 块体铰接带岩层移动模型的建立...................................................................................59 目 录 III 4.1 块体铰接带的形成过程及特征分析.........................................................................59 4.2.1 块体铰接带的形成过程及特征 .....................................................................59 4.2.2 块体铰接带移动建模的思路.........................................................................60 4.2 块体铰接带的岩层移动模型.....................................................................................60 4.2.1 DDA 法原理....................................................................................................60 4.2.2 块体的变形及位移模式.................................................................................61 4.2.3 块体系统的接触形式及嵌入判定..................................................................63 4.2.4 基于块体系统的基本关系及能量原理的总体平衡方程...............................65 4.2.5 总体平衡方程的求解.....................................................................................66 4.2.6 块体铰接带岩层移动模型的建立..................................................................67 4.3 本章小结 ...................................................................................................................67 5 似连续带岩层移动模型的建立.......................................................................................69 5.1 裂隙发育对岩层弹性模量的影响分析.....................................................................69 5.1.1 岩石单轴抗压强度与弹性模量的关系..........................................................69 5.1.2 基于裂隙发育的岩石弹性模量 .....................................................................70 5.2 似连续带岩层移动的模型建立.................................................................................72 5.2.1 薄板理论概述及岩层薄板可行性分析..........................................................72 5.2.2 似连续带移动挠度函数的确定 .....................................................................73 5.2.3 基于薄板的似连续带移动模型建立..............................................................75 5.3 本章小结 ...................................................................................................................79 6 弯曲下沉带及采空区上覆岩层总体移动模型的建立 ....................................................81 6.1 基于关键层和薄板理论的弯曲下沉带移动模型......................................................81 6.1.1 关键层理论概述.............................................................................................81 6.1.2 基于关键层和薄板理论的弯曲下沉带移动模型建立...................................84 6.2 岩层与地表移动的总体模型建立.............................................................................90 6.3 地表任意点移动与变形表达式.................................................................................91 西安科技大学博士学位论文 IV 6.3.1 地表任意点的下沉.........................................................................................91 6.3.2 地表任意点的倾斜.........................................................................................93 6.3.3 地表任意点的曲率.........................................................................................93 6.3.4 地表任意点的水平移动.................................................................................94 6.3.5 地表任意点水平变形.....................................................................................94 6.4 开挖空间形状的讨论................................................................................................95 6.4.1 基本开采空间地表沉陷的预计 .....................................................................95 6.4.2 不规则空间开挖地表沉陷的预计..................................................................96 6.5 本章小结 ...................................................................................................................97 7 结论 .................................................................................................................................99 7.1 主要结论 ...................................................................................................................99 7.2 创新点.....................................................................................................................101 致 谢 ...............................................................................................................................102 参考文献 ...........................................................................................................................103 附 录 ...............................................................................................................................111 1 绪论 1 1 绪论 1.1 选题背景与研究意义 1.1.1 选题背景 矿体被采出后,采空区周围岩体的自然应力平衡状态受到破坏,引起了应力的重新 分布,在此过程中,岩层和地表产生连续的移动、变形和非连续的破坏开裂、冒落等, 这种现象称为矿山开采沉陷Mining Subsidence。矿山开采沉陷学是以矿山岩石力学为 理论基础,研究矿产开采带来的地表损害、环境破坏及其治理工作的学科,是整个采矿 学科体系中不可缺少的重要分支。 近年来,随着我国社会经济的高速发展,资源和环境压力越来越大,环境污染和生 态破坏己成为危害人体健康,制约经济和社会发展的重要因素。矿产资源开发引起的环 境问题具有涉及面广、因素多等特点。据有关部门 1998 年公布的资料表明我国己探 明储量并具有开采价值的矿产资源种类达 150 余种,2000 多个县分布有各类矿山[1]。煤 炭作为已探明的主要能源,在我国能源结构占有很大的比例,大量的煤炭资源从地下采 出,引发了一系列的沉陷及其环境灾害问题[2],主要表现在以下几个方面 ⑴形成矿山压力显现。矿压压力的产生引起采场和巷道顶板的下沉、垮落和来压, 甚至引发冲击地压等强烈的矿压显现,危及井下人员和设备的安全。事实上,由于冒顶 事故引起的人员伤亡,一直占居煤矿各类伤亡事故的首位。1990 年以来,煤矿冒顶事故 死亡人数约占全部死亡人数的 45以上,随着支护技术的进步,这一数字有所下降,但 有效的控制顶板冒落,保障井下人员的生命安全仍是今后研究的一个重点。 ⑵形成采动裂隙。采动裂隙的出现引起周围煤体中的水和瓦斯的流动,导致井下瓦 斯事故和突水事故。 瓦斯爆炸、 煤和瓦斯突出一直是我国煤矿所面临的重大灾害, 仅 2001 年由于瓦斯事故的死亡人数达 2356 人,为煤矿事故总死亡人数的 40;同时,因煤矿 开采的瓦斯还加剧了温室效应,造成了严重的环境破坏。 ⑶岩层移动发展到地表引起地表沉陷。 地表沉陷的产生导致农田、 建筑设施的毁坏, 当地面潜水位较高时,地表沉陷盆地内大量积水,农田无法耕种,村庄被迫搬迁,引发 一系列的环境、经济和社会问题。 另外,随着煤炭业高强度和粗放型的开采,我国煤炭开采环境日趋恶化,开采条件 也日渐复杂,由此引起的一系列如地表沉陷、水土流失、土地荒芜等环境问题和安全问 题也越来越受到人们的重视。分析采动岩层与地表移动的机理,掌握岩层与地表移动的 规律、提出有效观测和预计方法,已成为开采沉陷学研究的核心问题。作为工程应用, 西安科技大学博士学位论文 2 一些特殊条件下的采煤,如承压含水层上采煤、公路和铁路下、建筑物下煤层开采的研 究也得到蓬勃的发展。 国内外“三下”建筑物下,水体下和铁路下压煤问题极其突出。我国仅煤炭生产 矿井“三下”压煤的工业储量就达