【作者】 陆银龙；

【导师】 王连国； Derek Elsworth；

【作者基本信息】 中国矿业大学 ， 工程力学， 2013， 博士

【摘要】 工程扰动作用诱发的岩体内部损伤和破裂及其造成的岩体渗流场改变是导致大规模岩体工程失稳和地质灾害的重要原因之一。在采矿工程中，采动矿压和煤层底板承压水压联合作用引发的底板突水灾害一直是威胁我国煤矿安全生产的重大问题之一。本文以煤层底板突水灾害为研究背景，综合运用理论分析、数值模拟和现场微震监测相结合的方法，对渗流-应力耦合作用下岩石损伤破裂演化过程以及煤层底板突水机理进行了深入、系统地研究，取得了如下创新性成果：(1)克服了经典的Biot孔隙弹性理论无法描述岩石介质内部结构损伤演化的局限，将微裂纹损伤张量引入到Biot孔隙弹性理论中，构建了基于微裂纹演化的岩石渗流-应力-损伤耦合模型，导出了应力诱导的微裂纹瞬时扩展和时间相关的微裂纹亚临界扩展的演化方程，建立了微裂纹损伤演化与岩石宏观弹性刚度张量、渗透张量、Biot有效应力系数张量、Biot模量以及声发射特征参数之间的联系。结合单个岩石REV分别承受渗流-应力耦合短期和长期作用的两个算例，验证了耦合模型在描述细观损伤引起的岩石宏观各向异性、峰前非线性强化、体积膨胀、声发射活动、渗透率演化以及蠕变行为方面的普适性和有效性。(2)提出了以细观单元组合和嵌在其中的随机分布微裂纹群来表征真实岩石介质的双尺度概念模型，据此将已建立的岩石渗流-应力-损伤耦合模型与宏观有限元模型有机结合，同时引入岩石介质的细观非均匀性、细观单元破裂准则以及破裂细观单元的刚度退化表征方法，建立了渗流-应力耦合作用下岩石损伤破裂演化的宏-细观双尺度数值模型，从根本上克服了传统岩石破裂过程数值分析模型中采用唯象估计方法的固有缺陷。将该模型应用于岩石双轴压缩-渗流耦合、岩石蠕变-渗流耦合以及岩石水力压裂等数值试验中，结果表明该模型能够以一种物理真实、可视化的方式有效地模拟出渗流-应力耦合作用下岩石从细观损伤演化至宏观破裂的全过程以及渗流动态演化规律。(3)基于建立的宏-细观数值模型，系统研究了承压水体上完整煤层底板和含陷落柱煤层底板的破坏突水过程，分析了工作面推进过程、顶板破断垮落压实作用、底板岩体非均质性、底板承压含水层水压力、时间效应等因素对底板隔水层损伤破裂和渗透性演化以及底板陷落柱损伤活化规律的影响，深入揭示了采动应力和承压水压力联合作用下底板“突水通道”形成与渗流突变机理，为我国承压水体上煤炭安全开采和煤层底板突水防治提供了参考依据。(4)采用高精度微震监测技术对某带压开采工作面回采过程中底板破裂的微震事件与微震能量强度进行了连续、动态地监测，并结合建立的宏-细观数值模型对该工作面煤层底板的破裂演化过程进行了数值模拟，准确地查明了底板采动破坏带的具体位置与参数，成功地指导了该带压开采工作面的安全高效生产；据此提出了将高性能微震监测技术和本文开发的岩石破裂过程数值模拟技术有机结合来实现煤层底板突水灾害监测预警的新方法，具有良好的工程应用前景。更多还原

【Abstract】 Fracturing evolution and its associated permeability change in rock, induced byengineering disturbance, usually result in the instability and geological disasters oflarge-scale rock engineering. In mining engineering, one of the problems which seriouslythreat coal mine production safety in China is the water inrush disaster which results fromthe combined effects of mining-induced stresses and confined aquifer pressure. Theevolution of fracturing and flow in rock under coupled hydraulic and mechanical loadinghas important theoretical and engineering significance in understanding and revealing themechanism of water inrush from coal seam floor and many other related rock engineering.Motivated by the water-inrush disaster in coal mine, the evolution of rock fracturing andthe mechanism of water-inrush from coal seam floor were investigated comprehensively bythe combined method of theoretical analysis, numerical simulation and in-situmicroseismic monitoring. The main conclusions are as follows:(1) The limitations of classical Biot poroelastic theory which cannot describe thechange of internal structure with rock media is overcame. The microcrack damage tensorwas introduced into classical Biot poroelastic theory and the microcrack-based coupledhydraulic-mechanical-damage model of rock was established. The governing equations ofstress-induced microcrack critical growth and time-dependent subcritical growth werederived, as well as the equations of elastic stiffness tensor, permeability tensor, Bioteffective stress coefficient tensor and Biot modulus. Two examples of the REV under theshort-term and long-term hydraulic-mechanical coupled loading were used to verify themodel and the results show the universality and effectiveness of the model in describinganisotropy, nonlinear strengthen, volume dilatation, permeability evolution, acousticemission activity and creep behavior of rock medium.(2) A two-scale conception model which assumes the macroscopic rock medium arecomposed of a series of microscopic elements in which random microcracks are embedded.Combining the microcrack-based coupled hydraulic-mechanical-damage model with FEMmodel, a combined macroscopic-microscopic numerical model for the analysis of rockfracturing was proposed, in which the heterogeneity of rock, the rupture criterion ofmicroscopic element and the stiffness degradation equation of the failed elements wereincorporated. The verification examples of biaxial compression and flow coupling, creepand flow coupling and hydraulic fracturing of rock specimen were employed to the checkthe model and the results show that the proposed model has the ability to replicate theevolution of fracturing and associated fluid flow within rock medium effectively. (3) The developed macroscopic-microscopic model was used to simulate water inrushprocess of the complete coal seam floor and of the coal seam floor containing collapsecolumn above a confined aquifer. The fracturing evolution of water-resisting layer of coalseam floor, permeability change, collapse column activation and the formation process of“water-inrush channel” were investigated and the influence of workface advancing process,roof rupture, heterogeneity of the floor, confined water pressure and time on fracturing andpermeability evolution were revealed. The results provide a significant guidance for safemining above confined water in China.(4) High precision microseismic monitoring technology was used to monitor themicroseismic events and energy intensity in a continuous and dynamic way in certain coalmine. Also, the proposed model was used to analyze the mechanism of water inrush fromcoal seam floor. A new method, combining high precision microseismic monitoringtechnology with numerical simulation of rock fracturing, was proposed to predict andforecast the water-inrush disaster of coal seam floor, which has a good prospect ofengineering application.更多还原