【作者】 杨永杰；

【导师】 宋扬；

【作者基本信息】 山东科技大学 ， 采矿工程， 2006， 博士

【摘要】 采用MTS815.03电液伺服岩石试验系统进行了大量煤样单轴压缩、三轴压缩、循环荷载及全应力应变过程的渗透性试验，同时进行了煤样压缩破坏过程的声发射试验及煤矿井下采场覆岩破裂失稳的微地震监测，对煤岩强度、变形及微震特征进行了较系统的分析研究。 通过扫描电镜测试和力学性质试验分析，发现煤在力学性质上表现为明显的不连续性、各向异性和非均质性特征，煤岩原生损伤变量对强度和变形影响很大。大量煤样超声波速度和相应的力学参数测试表明，煤样强度与其纵波速度间呈现置信度很高的指数函数相关关系，为进行强度等对比性试验前合理选择煤样以避免盲目试验提供了依据。 煤岩的声发射特征能较好地描述其变形和损伤演化特性。由于原生损伤发育，在围压作用下，煤岩孔隙裂隙被压密闭合，刚度增加，弹性模量与围压之间符合二次多项式关系。根据试验结果及模型简化拟合得出了常规三轴压缩条件下煤岩的分段本构方程。煤岩三轴压缩破坏符合Coulomb强度准则，但由于其内部存在大量微裂隙，煤样沿随机裂隙剪切破坏偏离θ₀=45°+φ／2的可能性很大。同坚硬致密的岩石相比，循环荷载作用下煤岩更容易发生疲劳破坏，煤岩疲劳破坏“门槛值”与其结构和组分等有关，其变形破坏过程与其损伤累计发展过程一致。煤岩渗透率—应变与其相应的应力-应变曲线总体趋势基本一致，但表现相对“滞后”，表明渗透率的变化与其损伤演化过程密切相关，同时煤体通过其内部裂隙的渗透需要一定的时间过程。根据试验结果拟合得出了煤岩渗透率—应变关系分段曲线方程。 通过声发射参数时间序列的最大Lyapunov指数计算，证实采用声发射参数描述的煤、岩压缩破裂演化系统的未来变化趋势不是完全呈现依赖于初值的混沌状态，是可以预报的。通过小波系数分解，发现采用不同尺度上声发射参数最先出现的Lipschitz指数α负值所对应的时间作为煤、岩压缩破裂预报时间，与实际情况吻合较好。通过对采场覆岩破坏微震事件的定位分析，证实微地震发展演化与采场覆岩运动密切相关。根据岩体失稳前微震事件频数、能量、距离的一到四阶差分的变化规律，能够较准确地预报岩体破裂，这对于采用微地震监测技术解决矿山岩体破坏失稳预报具有重要指导意义。更多还原

【Abstract】 Adapting MTS815.03 servo-controlled rock mechanical test system, a large number of tests of coal samples under uniaxial compression, triaxial compression, cyclic loading, permeability during the complete stress-strain path are carried out; besides, acoustic emission of coal and rock samples under uniaxial compression rapture process and microseism monitoring on fracturing and destabilizing of overburden strata of coal face are carried out. The characteristics of strength, deformation and microseism of coal are fairly analyzed and studied.Through analysis of scanning electronic microscopy measuring and mechanical test of coal samples, coal obviously has the mechanical characteristics such as discontinuousness, anisotropy and heterogeneousness. The strength and deformation of coal is largely influenced by the original damage variable. The exponential function relationship between the strength and the corresponding P-wave velocity of coal sample has high confidence degree which is regressed from test results of a large number of coal samples. This provides basis for choosing proper coal samples before carrying out comparative experiments such as strength in order to avoid blind experiments.The characteristics of deformation and rapture evolvement can fairly be described by the feature of acoustic emission of coal. Due to the development of primary damage, the micro-porosities and micro-cracks are compacted and closed by confining pressure, the stiffness of coal is increased and the relationship between elastic modulus and confining pressure conforms to quadratic polynomial function. The segmental constitution equation of coal is obtained through fitting method according to the triaxial compression test results and simplified model. The characteristic of triaxial compressive fracture of coal conforms to Coulomb strength criterion, but due to the large quantities of micro defects in coal, along therandom fissures, the possibility of fracture angle departed for θ₀ = 45° + φ/2 is big. Comparing with hardand compact rocks, coal is inclined to fatigue damage under cyclic loading. The value of fatigue damage "threshold" of coal is relative with its micro structures and micro components. The deformation and fatigue damage process of coal is in close accordance with its damage accumulation. The permeability rate-strain and stress-strain curves of coal are on the whole the same but the permeability rate-strain curve is relatively "hysteretic" which indicates that the close relativity between the evolvement of damage and the development of permeability rate and the permeability developing needs a time course. The segmental permeability rate-strain curve equations are obtained through fitting method according to the experimental results.更多还原