【作者】 高保彬；

【导师】 乔春生； 李化敏；

【作者基本信息】 北京交通大学 ， 地下工程， 2010， 博士

【摘要】 采动应力引起的煤岩节理裂隙的动态及空间分布的变化是伴随着采掘活动而不断发生发展的过程,这一过程控制着煤岩体内瓦斯的解吸、扩散、运移特征和能量的释放方式,决定着采掘空间瓦斯的涌出乃至突出的发生发展及演化。研究采动应力-裂隙-瓦斯涌出之间的内在规律,揭示采动力学过程与瓦斯运移及其时空关系,对研究煤与煤层气共同开采和瓦斯灾害治理具有重要的基础理论意义。本文针对矿井开采过程中采动应力场、围岩裂隙场和渗流场多因素交叉这一科学难题,采用RMT-150B岩石力学试验系统、JSM-6390LV钨灯丝扫描电镜、CDAE-1型声发射仪、自行研制的煤岩-气耦合渗透性双向加载试验系统做了大量细观、宏观角度的煤岩力学试验,研究了煤岩材料破裂过程中应力场-裂隙场-渗流场之间的演化关系,研究了模拟采掘工作面实际边界条件的煤岩裂隙演化及其透气性能演化过程,最后分析总结了采动煤岩-瓦斯耦合作用机理,并探讨了耦合作用对煤岩动力灾害影响。根据以上系统研究,取得了如下主要成果:（1）通过对大量的煤样单轴压缩破裂后的形貌描述和力学性质分析,归纳了煤岩在单轴压缩条件下六种主要破裂形貌和裂隙演化六阶段,特别提出了裂隙渐生段、裂隙速生段和裂隙扩展贯通段的概念。孔裂隙结构及断口形貌的扫描电镜细观分析结果表明煤岩宏观裂隙扩展和其内部微结构及微缺陷关系密切;（2）在煤、岩质量指标中,单轴强度对其声发射性能影响较大,而空隙性和声发射性能不具有相关性。基于裂隙演化特点,定义了裂隙渐生点σ_ci和裂隙速生点σ_cd,提出了采用裂隙速生点σ_cd和应力监测组合起来判断试样失稳破裂的前兆信息的方法。对不同应力路径下的煤样和砂岩试样的变形破坏过程研究后得到了裂隙演化过程中的声发射特性。建立了基于声发射参量的损伤模型;（3）自行研制了专利装置——准平面应变下煤岩-气耦合渗透性双向加载实验系统,用于模拟采掘工作面附近单元体的物理实际。试验研究了准平面条件下煤岩裂隙演化的四阶段,并提出煤岩失稳黄色前兆点和红色前兆点的概念。准平面应变下煤岩变形破坏过程的应力（应变）-裂隙-透气性变化试验结果表明了三者的关系变化;（4）系统研究了准平面应变下煤岩轴向应变-渗透率的相关性,给出了不同应变段应变-渗透率的数学表述;研究煤岩应力-渗透率相关性时发现渗透率增加多在峰值前,而渗透率突变多在峰后某一时刻,据此提出渗透率增加应力点和渗透率突变应力点指标:（5）加卸载应力路径下渗透性变化结果表明卸压对试样的渗透性能增加有重要作用,且不同应力阶段卸载气流增加量不同;恒定应力水平下气体压力变化对试样的声发射活动影响的结果表明在不同应力阶段气压发生变化产生声发射特征不同,但相对因应力变化产生的声发射密度和幅值均较低。更多还原

【Abstract】 Variation of dynamic and spatial distribution of coal joint fissures due to mining stress was along with the ongoing process of development of mining activities, the coal methane’s characteristics of desorption, diffusion and migration and the methods of energy release were controlled by the process, so the occurrence, development and evolution of the gas emission （even coal and gas outburst） in space mining were also controlled by such process. The study on finding the inner variation laws of mining stress-fracture-gas emission, revealing the space-time relationship on the mining mechanics process, gas migration was with basis theoretical significance on the research of joint exploitation of coal and coal-bed methane and gas disaster prevention.Based on the problems of mining pressure field, surrounding rock fracture field, seepage field in the process of mining, the thesis adopted the test system of rock mechanical RMB-150B, tungsten filament scanning electron microscope JSM-6390LV, acoustic emission detector CDAE-1, self-made bidirectional loading testing system of coal-gas coupling permeability and made plenty of coal mechanical tests from micro perspective and macro perspective, and then studied the time evolution of stress field, fracture field and seepage field during the fracturing process of coal materials, especially coal fracturing evolution and permeability evolutionary process under the simulated real boundary conditions of extraction face. At last, the coupling effect mechanism of mining coal and gas was analyzed, and the influences of coupling effect on coal or rock dynamic disasters were discussed.Based on the above systematic study, some main achievements having been made are as follows:Firstly, through the morphology descriptions and mechanical process analysis of uniaxial compression ruptured coal samples, this thesis summed up seven main fracturing features and six stages of fracturing involution, and in particular concepts of fracture slow-growing section, fracture fast-growing section, and fracture expanding and perforating section were brought up. SEM test results on pore and fissures structure and the morphology of the cut indicated that the macro cracks propagation have close relation to the micro-structure and micro-defects. Secondly, for the quality index of coal, uniaxial strength had great influence on its emission properties, but void property and emission property were not related. Based on the features of cracks evolution, concepts of fracture slow-growing pointσ_ci and fast-growing pointσ_cd were given, and the approach, combining fast-growing pointσ_cd with stress monitoring to judge the fracture portent of samples, was put forward. According to the deformation and failure process of coal sample and sandstone under different stress path, acoustic emission features were studied. Based on acoustic emission parameters, a damage model was built.Thirdly, quasi-plane strain bidirectional loading testing system on coal-gas coupling permeability was invented, which was used to simulate the physical activities of unit bodies near extracting coal face. The experiment studied the four evolution stages of coal fracturing under the condition of quasi-plane, and then concepts, yellow precursory point and red precursory point of coal instability, were brought forward. Under the condition of varying quasi-plane, the test related to the variety of stress （strain）- fracture- permeability in coal deformation and failure process showed the time relationship between the three factors.Fourthly, the correlation of axial strain and permeability of coal samples under condition of quasi-plane strain was analyzed systemically, and the mathematical expression of strain and permeability in different strain sections was given. Through studying the the correlation of stress and permeability of coal samples under condition of quasi-plane strain, it found that permeability often increased before the peak, while permeability mutation often appeared after the peak, thus the author drew concepts of stress point of permeability increasing and stress point of permeability mutation.Fifthly, Test results on the change of permeability under the load-unload stress path indicated that unloading had important role on the increasing of samples’ permeability, but the flow rates of increment were different under different stress stage. Experimental results on the influence of AE activities because of gas pressure changes under certain stable stress level showed that AE characteristics were different under different stress level, but the density and amplitude of AE parameters were lower than which were produced by variation of stress.更多还原