含水煤样动静组合加载力学响应试验研究.pdf

博士学位论文 含水煤样动静组合含水煤样动静组合加载加载力学响应力学响应试验试验研究研究 Experimental study on the mechanical response of water-saturated coal samples under coupled static-dynamic loading 申请人姓名 王 文 指导教师 李化敏 教授/博导 学位类别 工学博士 专业名称 矿业工程 研究方向 矿山岩体力学与工程 河南理工大学能源科学与工程学院河南理工大学能源科学与工程学院 二〇一二〇一六六年年六六月月 万方数据 II 万方数据 万方数据 IV 中图分类号中图分类号TD324 密密 级公开级公开 UDC622 单位代码单位代码10460 含水煤样动静组合加载力学响应及破坏试验研究 Experimental study on the mechanical response of water -saturated coal samples under coupled static-dynamic loading 资助项目国家自然科学基金面上项目（51274086） 河南理工大青年科学基金（72511/119） 申请人姓名申请人姓名 王王 文文 申 请 学 位申 请 学 位 工学博士工学博士 学 科 专 业学 科 专 业 矿业工程矿业工程 研 究 方 向研 究 方 向 矿山矿山岩体力学岩体力学与工程与工程 导师导师 李化敏李化敏 职称职称 教授教授/博导博导 提 交 日 期提 交 日 期 2016.04.07 答 辩 日 期答 辩 日 期 2016.06.08 河南理工大学 万方数据 万方数据 VI 致致 谢谢 工作几年又攻读学位，倍感机会的珍贵，又感到时间紧迫，三年太久，只争 朝夕。在论文成稿之际，感谢我的导师李化敏教授。他从论文的选题、研究方法、 方案制定、章节撰写及修改，倾注了大量的汗水与心血。他渊博的知识、敏锐的 思维、严谨的治学态度、锲而不舍的求是精神和诲人不倦的师者风范，永远启动 和指引着我以后的发展道路。在此，谨向恩师致以崇高的敬意和衷心的感谢。 感谢李东印教授、陆庭侃教授、袁瑞甫副教授、高保彬副教授、王开林老师 等在论文选题和撰写过程中给予的帮助和指导。 感谢苏承东教授级高工在静载试验及论文撰写方面给予的指导；感谢资环学 院邢智峰博士在煤样微观监测方面提供的指导与帮助；感谢硕士研究生顾合龙、 张广杰、王晨、候志强、孙浩在煤样的采集及加工等给予的支持。 感谢中南大学李夕兵教授、周子龙教授、宫凤强副教授、陶明博士、吴秋红 博士在煤样动静组合加载试验中给予的指导与帮忙。 感谢能源科学与工程学院、采矿工程系领导在工作及学习的帮助和支持。 在三年博士学习期间，还得到了李回贵、冯军发、刘闯、王明中、谭毅、徐 国胜等师兄弟的诸多帮助，在此表示感谢。 感谢家人的理解和关怀，他们默默的支持和无私的奉献是我能够完成学业的 坚强后盾和动力。 在此，向所有关心和帮助过我的领导、同事、同学等表示诚挚的谢意。 最后，向论文中所有文献的作者，是他们研究成果给我诸多的借鉴和引导， 使我对煤岩动力学的相关理论及方法有新的认识和理解，表示感谢。 最后衷心感谢各位评审专家在百忙之中给予评审和指导。 王 文 2016 年 6 月 万方数据 I 摘摘 要要 冲击地压是影响煤矿安全生产的重大灾害之一。冲击地压的形成常以震源冲 击应力波的方式通过煤岩介质传递至采掘空间，造成冲击地压事故，煤层注水是 冲击地压防治常用方法之一，静载型冲击地压煤层注水使冲击倾向性降低，但深 部煤层常处于动静组合加载的应力环境下，含水煤层的应力波传播衰减、强度、 能量耗散的强弱机理尚不清楚，含水煤样冲击动力响应是冲击地压防治亟待解决 的理论问题。利用 RMT-150C 和改进 SHPB 系统进行了煤样静载、动静组合加载 试验，探讨了不同含水煤样的动态强度、失稳破坏、应力波衰减、能量耗散、损 伤断裂等特征，主要结论及认识如下 （1）采用 RMT-150C 伺服试验系统对自然、饱水 3d、7d 煤样进行单轴和三 轴抗压强度的静载试验，单轴及三轴抗压强度随饱水时间增加而逐渐降低；三轴 压缩作用下自然和饱水 7d 煤样的应力-应变曲线峰后差异较明显， 自然状态煤样峰 后应力跌落速度较快（脆性破坏特征），饱水 7d 煤样峰后应力跌落较为缓慢（塑 性破坏特征）；基于微元强度服从 Weibull 分布，建立了单轴压缩含水煤样的统计 损伤本构模型，并进行验证。 （2）探讨了异形冲头法消除弥散效应和应力均匀问题，确定煤样动态加载尺 寸为50mm30mm； 饱水后煤样横波传播速度基本不变， 纵波传播速度增加明显， 应力波衰减系数减小；利用改进 SHPB 系统对自然、饱水 3d、饱水 7d 煤样分别进 行了一维动静组合加载试验，煤样的动态应力-应变曲线特征与静载差异较大，煤 样动态强度随饱水时间增加逐渐降低，但弹性模量少量升高，动态强度与弹性模 量高于静载强度及弹性模量；针对预加静载对煤样裂隙发展影响，将煤样裂隙分 为裂隙压缩稳定阶段、裂隙急剧扩展阶段、裂隙贯通阶段；煤样的动态强度呈现 先升高后降低的趋势，轴向预静载大于静载强度的 50-52（临界静载点）后， 一维动静组合动态强度开始下降。 （3）三维动静组合加载的相同围压不同轴压试验中，轴向静载在煤样弹性范 围内其动态强度随轴向静载增加而增加，饱水 7d 煤样的动态强度比自然状态煤样 有不同程度的增高，与静载、一维动静组合加载结果相反；相同轴压不同围压加 载时，随着围压增大自然和饱水 7d 煤样的动态强度均有增大，弹性模量也相应增 加；对一维、三维动静组合加载煤样的应力-应变曲线特征分为 4 个阶段压密阶 段、弹性阶段、裂纹扩展阶段、卸载阶段。 万方数据 II （4）运用断裂损伤力学理论，分析了裂隙尖端应力场演化特征，建立了静载、 动静组合加载条件下含水张开翼型裂纹模型；分析了裂隙水压作用下煤样裂隙动 态起始、传播与止裂判据，建立了静载、单独动载、动静组合加载条件下含水煤 样的抗压强度数学表达式，并探讨了含水煤样及岩石类材料动态抗压强度增加或 降低的原因；确定了一维动静组合加载含水煤样损伤变量，建立了含水和动静组 合加载条件下煤样的本构模型，并对模型进行验证。 （5）一维动静组合加载自然煤样破坏所需时间大于饱水煤样破坏需要时间， 煤样破碎颗粒随饱水时间增长而逐渐变小；相同含水试样破坏失稳耗散能量越大， 破碎块度越小，分形维数越大；自然煤样分形维数小于饱水 3d、7d，分维数随着 能耗密度的增加而提高，能耗密度与分形维数增幅均呈正相关；相同能耗密度随 饱水时间增长粒度逐渐减小，能耗密度与破碎粒度呈负相关，二者具有良好线性 关系，水作用对试样粒径影响显著。 关键词关键词岩石力学；霍普金森压杆；动态强度；损伤；能量耗散 万方数据 III Abstract Rock burst is one of the major disasters in coal mine. It may be caused by the static and static-dynamic loading conditions. During the rock burst, the hypocerter shock stress wave transmitted through rock and coal seams may cause the major damage to the underground structures, facilities and even mine personals. Coal seam water injection is one of the commonly used s for preventing and controlling the occurrence of rock burst, as the water may reduce the possibility of occurrence of rock burst under static loading condition. On the othe hand, in the deep coal seam, the rock burst is caused by the combination of static and dynmic loading. Under such a loading condition, the stress wave propagation and attenuation, the strength variation of coal and the disappearing characteristics of energy in the water bearing coal seam are not clear. Therefore, the experimental investigation on dynamic response of water-saturated coal samples is conducted using RMT-150B testing machine and modified SHPB system. With the static and dynamic loadings applied, the dynamic strength and stability, the attenuation of stress wave, the energy disappearing as well as the damage and fracture characteristics of different water-saturated coal samples are tested and studied. The major findings are summarized as follows 1 Static uniaxial and triaxial compressive tests have been conducted on the coal samples, which are in the natural condition and placed in water for 3 and 7days respectively. It is noted that uniaxial and triaxial compressive strength decrease with the increase of the coal sample in the water. Under the triaxial compressive loading, the post-peak of stress - strain curve of the coal samples placed in the natural and water for 7days presents different features. The brittle character has been detached for the samples in the nature condition, and plastic behavior has been identified for the samples placed in water for 7 days. Also, the statistical damage constitutive model of water-saturated coal samples under uniaxial compression loading is established on the basis of Weibull distribution, and the model verification has been conducted accordingly. 2 Special-shaped punch has been used to liminate dispersion effect and uni stress. Also, the size of coal sample is has been determined as 50mm30mm for dynamic loading tests. For the water-saturated coal sample, the shear wave velocity 万方数据 IV is basically unchanged, the longitudinal wave velocity increases obviously, and the stress wave attenuation coefficient decreases. Also, one dimensional static and dynamic loading testwas carried out by using the modified SHPB system for the samples placed in the natural, and water for 3 days and 7 days. The stress-strain curve of coal samples between dynamic and static loadhas obvious difference. The dynamic strength of coal samples will decrease with the time placed in water increased, but the modulus of elastic only has a slightly rise. The dynamic strength and modulus of elasticity is higher than the static strength and the modulus of elasticity. The fracture propagation of coal samples may be divided into few stages, including the stage of fracture compression stable, the stage of crack sharp expansion, the stageof crack coal essence according to the influence of axial pre - static load on the development of coal - like crack. The dynamic strength of coal sample increases initially and then decreases afterward. Axial pre-static load is greater than 50-52 of the static load strength Critical dead load point, the dynamic strength of one-dimensional static-dynamic combination began to decline. 3The dynamic strength of axial static load in the elastic range of coal sample increases with the increase of the axial static load under the three dimensional static and dynamic loading tests with the same confining pressure and different axial compression. The dynamic strength of coal samples in water for 7 days is higher than the one in the natural condition, but it is lower under the static loading and one dimensional static-dynamic loading conditions. The dynamic strength and the modulus of elasticity of coal samples placed in the natural and in water for 7days increase with an increasing of confining pressure under the same axial compressionand different confining pressure. The stress-strain curves of coal samples under one dimensional and three dimensional static-dynamic loading are divided into 4 stages compaction stage, elastic stage, crack growth stage and unloading stage. 4 The stress field evolution characteristicsof crack tip are analyzed, and the crack model of water-saturated open wing under the condition of static and dynamic-static loading was established by using the fracture damage mechanics. The fracture initiation, propagation and stop criterion of coal sample under the action of hydraulic pressure has been proposed. The mathematical expressions of the compressive strength of 万方数据 V water-saturated coal sample under the condition of static loading, dynamic and dynamic- static loading conditions were established. The variation mechanisms of the dynamic compressive strength of the water-saturated coal sample and the rock material were also presented. The water-saturated coal sample damage variableunder one-dimensional dynamic-static combined loading was determined. The constitutive model of water-saturated coal sample under the combination of static and dynamic loading was established, and verified. 5 The time for the destruction of natural coal samples under one-dimensional dynamic-static loadingis greater than water-saturated coal samples. The broken particles of coal samples gradually become smaller with the increase of water saturation time. The greater failure instability dissipative energy, the smaller the fragmentation degree, the greater the fractal dimension. The fractal dimension of coal sample in the natural condition is less than the samples placed in water for 3days, 7days respectively. The fractal dimension increases with an increasing of the density of energy consumption, which indicates a positive correlation. The grain size decreased with increasing saturation time under same density of energy consumption, which shows a negative correlation. The grain and the density of energy consumption have a great linear relationship. The effect of water on the size of the sample is significant. Keywords rock mechanics； Hopkinson pressure bar； dynamic strength； damage； energy dissipation； 万方数据 VI 万方数据 VII 目目 录录 摘摘 要要 ............................................................................................................................ I Abstract ........................................................................................................................ III 目目 录录 ......................................................................................................................... VII 1 绪论绪论 ........................................................................................................................... 1 1.1 选题意义选题意义 ............................................................................................................... 1 1.2 国内外研究现状国内外研究现状................................................................................................... 2 1.2.1 含水煤岩静态、动态力学特性研究现状 ............................................................ 2 1.2.2 含水煤岩损伤断裂及本构研究现状 .................................................................... 5 1.2.3 需进一步研究的科学问题 .................................................................................... 7 1.3 主要研究内容及方法主要研究内容及方法 ........................................................................................... 8 1.3.1 主要研究内容 ........................................................................................................ 8 1.3.2 技术路线 ................................................................................................................ 9 2 含水煤岩的物理化学特性含水煤岩的物理化学特性 ........................................................................................ 11 2.1 含水煤样制含水煤样制 ......................................................................................................... 12 2.1.1 煤样采集 .............................................................................................................. 12 2.1.2 煤样制备 .............................................................................................................. 13 2.1.3 煤样的饱水处理方法 .......................................................................................... 15 2.2 煤岩宏观及微细观裂隙形貌分析煤岩宏观及微细观裂隙形貌分析 ..................................................................... 16 2.2.1 煤岩宏观裂隙分布特征 ...................................................................................... 16 2.2.2 煤岩微细观裂隙分布特征 .................................................................................. 17 2.2.3 饱水前后煤岩裂隙微观特征 .............................................................................. 23 2.3 含水煤样水化腐蚀损伤效应特征含水煤样水化腐蚀损伤效应特征....................................................................... 24 2.3.1 水化腐蚀损伤对煤体的影响 .............................................................................. 24 2.3.2 水化腐蚀损伤化学过程分析 .............................................................................. 26 万方数据 VIII 2.4 小结小结 .................................................................................................................... 28 3 静载作用含水煤样力学试验静载作用含水煤样力学试验 ..................................................................................... 31 3.1 静载岩石力学试验方案静载岩石力学试验方案 ...................................................................................... 31 3.1.1 试验系统及控制变量概况 ................................................................................... 31 3.1.2 含水煤样静载试验方案 ........................................................................................ 34 3.2 静载含水煤样力学试验分析静载含水煤样力学试验分析 ............................................................................... 35 3.2.1 含水煤样单轴压缩试验分析 ............................................................................... 35 3.2.2 含水煤样三轴压缩试验分析 ............................................................................... 37 3.2.3 煤样变形与破裂过程分析 ................................................................................... 40 3.3 静载作用含水煤样损伤本构模型静载作用含水煤样损伤本构模型 ....................................................................... 41 3.3.1 静载损伤本构模型建立 ....................................................................................... 41 3.3.2 本构模型参数确定 ............................................................................................... 43 3.3.3 损伤本构模型验证 ............................................................................................... 44 3.4 小小 结结 .................................................................................................................. 45 4动静组合加载含水煤样动力学动静组合加载含水煤样动力学试验研究试验研究 ................................................................... 47 4.1 煤岩动力学测试原理及方法煤岩动力学测试原理及方法 ................................................................................ 47 4.1.1 SHPB 装置实验原理 .............................................................................................. 47 4.1.2 一维动静组合加载实验装置 ............................................................................... 50 4.1.3 三维动静组合加载 SHPB 实验装置 .................................................................... 52 4.1.4 动静组合加载试验步骤及方案 ............................................................................ 53 4.2 动载作用煤样尺动载作用煤样尺寸效应研究寸效应研究 ............................................................................... 54 4.2.1 波的弥散效应和应力均匀问题 ........................................................................... 54 4