【作者】 李波波；

【导师】 许江；

【作者基本信息】 重庆大学 ， 矿业工程， 2014， 博士

【摘要】 煤矿开采历程中，长期以来将煤层瓦斯视作煤矿井下安全生产第一灾害，提高煤层渗透率，从而增强煤层瓦斯抽采效果，减少安全生产隐患，并抽采出来作为清洁能源加以利用，因此，煤岩损伤演化及其渗透机理一直是我国煤矿安全研究领域的重点和难点。为增强对煤岩损伤演化及渗透性的认识，本文以重庆松藻煤电有限责任公司松藻煤矿K1煤层、K2煤层和山西晋城无烟煤业集团有限责任公司赵庄矿3#煤层的煤为研究对象，从煤岩三轴应力状态、周期性采掘扰动及煤层降压瓦斯抽采等条件出发，采用实验室测试和理论研究结合的方法，系统地开展了煤岩孔裂隙特征及其吸附解吸特性、三轴应力状态下煤岩损伤演化与渗透机理、周期性采掘扰动下煤岩损伤演化与渗透机理、煤层降压瓦斯抽采过程中煤岩损伤演化与渗透机理、多场耦合渗透率模型及渗透率敏感性分析等方面的研究，并结合岩石力学、渗流力学及损伤力学从理论层面上进行了一系列有益的探讨。通过本文研究，在以下方面取得了一些进展：1)分析了煤岩原生孔裂隙结构特征，并利用HCA型高压容量法吸附装置对其吸附瓦斯特性进行了试验研究，得到了不同温度下的等温吸附曲线及吸附常数a、b值随温度的变化规律。2)开展了三轴应力状态下不同温度、不同粒径、不同瓦斯压力条件下(温度)的力学特性及渗流特性试验研究，并在不同开采方式下的加卸载试验中进行了三种不同卸载速率条件下的试验研究，分别探讨了煤岩的变形特性、渗透特性等损伤演化规律及其煤岩变形与渗透率关系。3)利用统计损伤的概念和方法，建立了考虑三轴应力状态及温度的煤岩统计损伤本构模型，并通过试验所测得数据对其实用性及合理性进行了验证，结果表明，考虑温度的煤岩统计损伤本构模型的理论曲线能够较好地反映实测煤岩损伤演化趋势，其统计损伤本构模型理论计算数据能够较好与实验测定曲线吻合。4)通过不同温度、不同粒径和不同稳定时间条件下的煤岩周期性荷载试验研究了周期性采掘扰动下煤岩损伤演化与渗透机理，系统地探讨了煤岩加、卸载阶段的主应力差、渗透率与轴向应变关系，并分析了3种条件下的单次循环变形及渗透特性，变形、渗透率随时间和循环次数关系等变化规律；探讨了不同稳定时间条件下煤岩渗透率变化滞后于体积应变。5)通过不同温度条件下周期性荷载试验，探讨了煤变形的能量演化机制，从能量角度出发，突出了煤在不同温度条件下循环荷载作用过程中的能量转化关系及应变能转化速率的研究，分析了吸收能、弹性应变能、耗散能随循环次数及温度的变化规律；基于能量耗散分析建立的煤岩损伤演化方程进行了验证，测定了相关参数指标，较好地描述煤岩在压缩时的损伤演化过程，探讨了能量耗散与损伤的关系。6)通过不同应力、不同温度条件下(CH4、He)的气体压力降低渗流试验，分析了煤层降压瓦斯抽采过程中煤岩变形特性和渗透特性，并探讨了不同应力条件下煤岩的吸附膨胀、解吸基质收缩变形和有效应力对渗透率影响、不同温度下煤岩应变随气体压力和温度的变化趋势、煤岩渗透率随气体压力下降呈先减小后增大的趋势、煤岩渗透率随温度的升高呈现先减小后增大的趋势以及渗透率和体积应变关系，研究了煤岩割理压缩系数的可变性。7)基于Jishan Liu模型、Shi-Durucan模型以及煤岩多孔介质均质、各向同性热弹性的有效应力与应变关系，在考虑应力、温度和瓦斯的吸附解吸等因素以及改进其算法和条件的基础上，建立了多场耦合渗透率模型，通过试验数据验证和及其与P&M模型和S&D模型的对比分析，证明所构建的渗透率模型能够较好地反映实测渗透率的变化趋势；通过定义气体压力敏感性系数和温度敏感性系数，推导了基于敏感性系数的煤岩渗透率与气体压力、温度的函数关系式开展了不同气体压力和不同温度条件下煤层渗透性的敏感性分析。更多还原

【Abstract】 During the safety production of coal mining history, the gas has long been regardedas first one of all disasters. Improving permeability of coal seam is very important toenhance the effect of coal seam gas extraction and to reduce safety risks as well as toextract the gas as a clean energy. Therefore, the damage evolution and the penetrationmechanism of coal and rock have been the focus and difficulty of coal mine safetyresearch in China. In order to know more about the damage evolution and permeabilityof coal, using coal from Songzao K1, K2seam of Chong qing Songzao LLC and ShanxiJincheng Anthracite Coal Industry Group Co., Ltd. affiliated Zhaozhuang mine3#coalseam as the reseach objects to conduct experiments. Based on coal and rock triaxialstress state, cyclical mining disturbance, and gas extraction from coal seam step-downconditions, the coal and rock pore fracture characteristics and its adsorption desorptioncharacteristics, damage evolution and penetration mechanism under triaxial stress state,the periodic mining disturbing and gas step-down extraction process weresystematically studied, multi-field coupling permeability model and the permeabilitysensitivity was also systematically analysed by conbining the laboratory test andtheoretical research. And a series of useful disscussion was made from the theoreticallevel by combining with rock mechanics, seepage mechanics and damage mechanics.Through the research, some progresses were made in the following aspects:1) The native bore and fractures of coal were analysized. By using HCA-pressurevolumetric method, the gas adsorption characteristics of coal at different temperaturesand the variation law of adsorption constants a, b with temperature were experimentalstudied.2) Mechanics and seepage characteristics tests were carried out at differenttemperatures, particle sizes, gas pressures (temperature) under triaxial stress state and atthree different unloading rates under loading-unloading stress state in different miningmethods. The deformation characteristics, permeability during the evolution of damageand the relationship between deformation and permeability of coal were discussedrespectively.3) Using the concept and method of damage statistics, a statistical damageconstitutive model considering triaxial stress state and temperature was established itspracticality and rationality were verified by test data. The results show that the theoretical curve considering the temperature of coal and rock statistical damageconstitutive model can better reflect the actual trend of coal and rock damage evolution.The theoretical calculations data of the statistical damage constitutive model can bebetter fitted with experimental measurement data.4) The coal and rock damage evolution and penetration mechanism under cyclicalmining disturbance were studied by experiments at different temperatures, particle sizes,stabilization time. The relationship between main stress, permeability and axial strainduring load-unload stage were systematically discussed. The deformation andpermeability characteristics and their relationship with time under three conditions in asingle-cycle were anlyzed. Permeability changes lags volumetric strain changes atdifferent stability time.5) Through the periodic load tests under different temperature conditions, energyevolution mechanism of coal deformation were discussed.From the perspective ofenergy, study on energy conversion relationship and strain energy conversion rate atdifferent temperature during the periodic load were highlighted. The changing law ofabsorbed energy, elastic strain energy and dissipation energy with cycles andtemperatures were analyzed. The damage evolution equation of coal and rock based onthe analysis of energy dissipation was verified, and the related parameters were tested.And this equation describes the damage evolution process of coal and rock duringcompression. The relationship between energy dissipation and damage was discussed.6) The deformation and seepage features during the reducing of gas pressure wereanalyzed by gas pressure reducing seepage tests at different stresses and temperatures(CH4, He). Influence from the adsorption expansion and desorption matrix shrinkagedeformation of coal and rock, effective stress on permeability under different stressstates was discussed. Trend of coal and rock strain with the gas pressure droping andtemperature under different temperatures was analyzed. Coal and rock permeabilitydecreases first and then increases with the gas pressure droping, and also does with thetemperature increasing. The relationship between volumetric strain and permeabilitywas also analysed. Variability of coal and rock cleat compression coefficient wasstudied.7) Based on the permeability model of Jishan Liu and Shi-Durucan as well as therelationship between the effective stress and the strain of homogeneous porous mediuand isotropic thermoelastic, considering stress, temperature, adsorption and desorptionof gas and improving its algorithm and conditions, multi-field coupling permeability model was established. The new permeability model is proved to reflect the changingtrend of the measured permeability well by verifying the test data and making a contrastwith P&M and S&D models. By defining the gas pressure sensitivity coefficient andtemperature sensitivity coefficient, the function relation between the permeability andgas pressure, temperature based on the sensitivity coefficient was deduced. Andsensitivity analysis of permeability under different gas pressures and temperatures werestudied.更多还原