【作者】 卢兴利；

【导师】 刘泉声； 郑宏；

【作者基本信息】 中国科学院研究生院（武汉岩土力学研究所） ， 岩土工程， 2010， 博士

【摘要】 当前,随着我国国民经济的迅速发展,水利、交通、冶金、煤炭等各行业地下工程的规模和深度均呈增大趋势,特别是煤炭行业,矿井开采深度正在逐年增加。深部岩体处于复杂的地质环境中,高地应力、高地温、高渗透压以及强时间效应,使得深部岩体的组织结构、基本行为特征和工程响应与浅部岩体相比均发生了根本性变化。在这些因素共同作用下,即使是在浅部表现为坚硬稳定的岩体,在深部一般也会表现出显著的软岩特征,且由于存在着高赋存地应力和围岩体低强度之间的突出矛盾,深部地下工程开挖后造成的应力集中和应力重分布将导致很大范围内的岩体进入峰后破裂状态,而且这个过程中也往往伴随着破裂围岩的非线性大变形。本文针对煤矿深部巷道围岩普遍处于破裂状态,且表现出强烈非线性大变形的特点,采用能够表征破裂岩体几何非连续性特征以及模拟巷道围岩大变形的非连续介质方法,提出一种深部巷道破裂岩体块系介质模型,并以此为出发点,在系统科学思想指导下,采用试验研究、理论分析和数值模拟相结合的方法,分别进行了岩石块体力学特性研究、岩块间胶结界面力学特性研究以及硐室周边破裂岩体结构特征模拟方法研究。最后,综合集成上述研究成果,将所提出的深部巷道破裂岩体块系介质模型应用于淮南矿区顾北煤矿-648m水平南翼回风大巷的围岩稳定性分析中。概括来讲,本论文的主要研究内容如下：1)基于淮南矿区顾北煤矿深埋段砂岩常规三轴压缩以及峰前卸围压试验的结果,从变形、强度、破坏等不同角度对砂岩在不同应力路径下的变形和强度特征进行了较为系统的分析,获得了岩石基本力学特性,并揭示了岩石扩容—碎胀变形破坏机理,明确了岩石峰后碎胀变形是导致破裂围岩非线性大变形的主要原因。2)在前述试验基础上,研究了各特征应力值(裂纹闭合应力σcc、初始扩容应力σci、损伤扩容应力σcd、以及峰值应力σf)随围压变化的演化特征,提出了经验的砂岩进入峰前损伤扩容与峰后碎胀变形的临界条件准则,并考虑岩石峰前非弹性变形特点及卸荷过程中力学参数(粘聚力、内摩擦角、膨胀角)的损伤劣化过程,建立了反映深部岩石峰前损伤扩容与峰后破裂碎胀变形的渐近破坏本构模型,进而推导了本构模型的增量迭代格式,并在离散元数值分析软件UDEC中进行了数值实现以及模型验证,证明了该模型的有效性。3)基于经典的弹塑性理论,以块体接触界面抗拉、抗剪屈服函数为屈服准则,且考虑块体接触界面屈服破坏后粘聚力、抗拉强度的渐近软化,建立了块体胶结界面弹塑性本构模型,并推导了上述本构模型的增量迭代格式,进而采用VC++语言编制了相应的自定义本构模型,将其嵌入到离散元软件UDEC中,最后通过数值直剪试验,证明了此嵌入的数值本构模型与UDEC中内置的含残余强度的Coulomb滑移模型模拟结果的优越性。4)针对深部巷道地下硐室周边破裂岩体结构特征及动态力学行为,结合Voronoi图的多样性,提出Voronoi离散块体模型,指出了该模型的特点,并借鉴PFC2D软件中微观力学参数的获取方法,研究了其微观力学参数的校准方法,同时对各微观力学参数变化对材料宏观特性(主要指弹性模量及抗压强度)的影响进行了敏感性分析,进而得到了各微观力学参数的取值原则。5)以淮南矿区顾北煤矿-648m水平南翼回风大巷为工程实例,在前述对岩石变形破坏机理认识以及提出的岩石扩容—碎胀渐近本构模型、块体胶结界面本构模型以及Voronoi离散块体模型基础上,主要集中于开展深部巷道围岩破裂演化规律及开挖支护对策的研究工作。首先根据巷道所处工程区的地质条件建立相应的计算模型,并根据室内岩石物理试验结果,通过双轴数值试验校准确定相应的微观力学参数取值,进而从工程应用的角度系统地从位移矢量场、主应力矢量场、塑性屈服区以及破裂损伤区分布及其深度和大小等不同角度分析和总结了围岩体破裂演化规律和特征,并据此提出“分步联合支护”的设计方案,最后通过数值仿真分析和现场支护试验研究,从理论和实践上验证研究了该支护方案的有效性,这些问题的研究为深部破裂岩体中巷道工程的科学设计和安全施工提供了科学依据。更多还原

【Abstract】 At present, as the rapid development of national economy, the scale and depth of underground engineering tends to increase in various industries mainly including water conservancy, transportation, metallurgy, coal and so on, especially in the coal industry, mining depth of the coal is increasing year by year. Comparing with the shallow rock, the deep rock mass located in complicated geology environment, the high stress, high temperature, high seepage pressure and strong time-dependent effect cause essential changes in mechanics structure, basic behavior characteristic and response to project of deep rock. Influenced by these factors, the deep rock mass exhibits marked characteristics of soft rock, though it is hard and steady in shallow. For the existence of sharp contradictory between the high ground stress and low strength of surrounding rock mass, the stress concentration and stress redistribution made by the excavation of the deep underground project result in a wide range of rock mass entering the fracturing condition after peak, and during the process, it is often accompany the nonlinear large deformation of the cracked rock mass.Aim at the broken status and the characters of strong nonlinear mechanical phenomenon of surrounding rocks in deep coal mine, a model of blocks for cracked rock mass of deep roadway is proposed. Then combining the experiment research, theoretical analysis and numerical simulation, this paper systematically studies the mechanics feature of rock blocks, block bonding interface and the structural characteristic of cracked rock mass around the roadway. Lastly, the fruits of the above studies are applied to analyze the stability control of the return airway at the -648 m level of Gubei colliery in Huainan mining area.Generally, the main research works included in the dissertation are as following:1) Based on the multi-angle experimental results of sandstone in Gubei colliery, such as conventional triaxial compression tests and pre-peak unloading confining pressure tests, a more systematic analysis on the deformation and strength characteristics of the soft rocks under different circumstances in different states of stress is carried out from the deformation, strength, and failure view, which has access to the basic mechanical properties and the dilatation-bulking deformation and failure mechanism of the rock. It is clear that post-peak bulking deformation is the main reason of the nonlinear large deformation of cracked rock mass.2) Based on the results of experimental test, the evolution characteristics of the typical stress values(including crack closure stressσcc、initial dilatancy stressσci、damage dilatancy stressσcd and peak stressσf) with the confining pressure are researched. And the experimental critical condition criterion of sandstone entering pre-peak damage dilatancy and post-peak bulking deformation is proposed. Then considering the pre-peak inelasticity characteristic of rock, and the damage and degradation process of mechanics parameters (cohesion, angle of internal friction, dilation angle) during unloading, a progressive failure constitutive model, which can reflect pre-peak damage dilatancy and post-peak bulking deformation of the deep rock mass is established. The incremental iterative scheme of the constitutive model is derived, its numerical implementation and model verification are proceeded by using the UDEC (universal distinct element code) and the validity of the model is proved. 3) Based on the classical elastoplasticity theory, a block bonding interface elasto-plastic constitutive model is established by using tensile and shear function of the block contact interface as yield criterion and considering the progressive soften of the cohesion and tensile strength after the block bonding interface yield failure. The incremental iterative scheme of the above constitutive model is then derived, and the program about the constitutive model is compiled by VC++ Programming Language, and embedded it in the distinct element code UDEC. At last, by the numerical direct shear test, the advantage of the numerical constitutive model embedded is proved comparing the simulation results with the UDEC built-in Coulomb slip model with residual strength.4) Aim at the structural characteristics and the dynamic mechanical behavior of cracked rock mass of deep roadway among the underground cavernunderground cavern, a Voronoi discrete block model is proposed combining with the variety of the Voronoi figures. Then the characteristic of the model is pointed out and the calibration technique of micromechanics parameters is studied by referring the PFC2D’s method to obtain the micromechanics parameters. At the same time, the sensitivity analysis about the variation of the micromechanics parameters impacted on the macro-deformation characteristics of materials (mainly the young’s modulus and compressive strength) is carried out, and the adoption principle of the micromechanics parameters value is obtained further more.5) Using the return airway at the -648 m level of Gubei colliery in Huainan mining area as an engineering example, the researches about failure evolutionary process of surrounding rock in deep roadway and the plan of excavation support are carried out on the basis of the deformation and failure mechanism of rock mass, the dilatancy-bulking progressive constitutive model, the block bonding interface constitutive model and Voronoi discrete block model. Firstly, According to the geological conditions of the return airway, a corresponding computational model is proposed, following the laboratory experimental results, the corresponding micromechanics parameters are determined by means of numerical biaxial compression test. And then failure evolutionary law and characteristic of surrounding rock mass are systematically analyzed and summarized from the views of displacement vector field, the primary stress vector field, as well as size and depth of the plastic yielded zone and broken bulking zone. On this basis the stepped combined support method is put forward and lastly by the numerical simulation and field monitoring, the availability of the support method is verified both from theory and practice, so as to provide important basis for scientific designing and safe construction of engineering in deep roadway cracked rock mass.更多还原