【作者】 张东明；

【导师】 尹光志；

【作者基本信息】 重庆大学 ， 采矿工程， 2004， 博士

【摘要】 岩石的局部化变形是岩土材料失稳的一个重要特征，是材料破坏的先兆，岩石中的局部化变形直接导致了加载过程中岩石整体强度的降低，使岩体工程的承载力下降。所以研究和预测局部化变形带的起动、演化发展及剪切带形成规律对于研究岩石材料失稳破坏具有非常重要的意义。本文应用理论研究、实验研究和数值分析相结合的方法，对软岩的局部化起动、演化、形成宏观剪切带及失稳破坏进行了深入系统的研究，得到了一些有益的研究成果： (1) 通过重庆红色泥砂岩单向、三向受压状态下的实验研究，分析了软岩的损伤演化规律及裂纹扩展的非线性分形特征。在此基础上结合岩石强度概率分布假设，采用重正化群模型对岩石失稳破坏过程中的临界现象进行了研究，得到了岩石材料失稳破坏的理论临界点。通过实验数据与重正化群模型计算结果的对比，证明了重正化破坏模型能准确地模拟岩石的失稳破坏，并能有效地推测出破坏的临界点，建立判断岩石稳定状态的判据。 (2) 基于岩石变形局部化与失稳破坏过程中的自组织临界特征，采用“沙堆元胞自动机”模型，从新的角度对岩石变形过程中的裂纹扩展、损伤演化以及能量释放等细观尺度上的自组织临界行为进行了研究。 (3) 自行研制了平面应变加载系统，首次研究了重庆红色泥砂岩在平面应变加载条件下的变形局部化行为及失稳破坏机理。对平面应变加载过程中的弹性波速变化特征进行了研究，跟踪了岩石变形局部化的演化全过程，并根据弹性波测试结果得到了软岩变形局部化的起动点和失稳破坏的临界点。同时，还研究了平面应变条件下，加载速率、含水量及坡角的变化对软岩变形局部化发生和发展的影响规律。 (4) 采用先进的激光数字散斑光测方法，对泥砂岩和泥岩两种软岩试件进行变形局部化对比实验研究。研究了单轴压缩状态下，加载速率对软岩变形局部化的影响。经过一系列散斑干涉的相关分析，实时、定量地跟踪和测定了软岩变形局部化的变化规律，首次观测到了泥砂岩和泥岩变形局部化带的“转动”全过程，并确定了局部化起动的时刻，定量地测定了局部化带的宽度及局部化带内的变形速度。 (5) 基于岩石的弹塑性本构关系，采用滑块—弹簧组合系统研究了岩石剪切带形成的力学模型，并得出了该力学模型控制的变形局部化起动条件。 (6) 基于材料失稳破坏的分叉理论，对软岩变形局部化进行理论研究，以确定软岩变形局部化起动条件以及局部化方位角等理论模型。对弹塑性材料变形局重庆大学博士学位论文部化进行分叉分析。根据Maxwell不相容条件，对岩石在平面应变和平面应力状态下的局部化准则进行了理论分析。 (7)基于材料变形破坏的梯度塑性理论，对岩石变形局部化带的理论宽度进行了分析，并根据实验数据得到了泥砂岩的内部长度以及单轴压缩和平面应变状态下局部化带的宽度。 (8)基于岩石微元的强度分布函数满足威布尔分布的假设，采用RFPAZD对岩石单轴受压、等围压三轴、平面应力以及平面应变几种状态下的局部化剪切带形成过程和失稳破坏进行了数值分析。更多还原

【Abstract】 The deformation localization of the rock is both an important characteristic of the rock material’s instability and the symptom of material failure, which directly leads to the decrease in its overall intensity during the loading process and the loading-bearing capacity of the rock project.Therefore, the study and prediction of the initiation and evolution of the deformation localization band and the evolution rule of the shear band are very meaningful to the exploration of the rock material’s instability and failure. In this paper, applying the methods of theoretical study and experimental study as well as numerical analysis, from a new point of view, the author makes a thorough and systematic study of the soft rock’s deformation localization from its initiation, evolution, and taking shape into macro-shearing band and its instability as well, and yields some positive research results.(1) Through the experimental study of red mud sand rock in Chongqing under the conditions of uniaxial and triaxial loading, the author analyzes the damage evolution law of the soft rock and the nonlinear fractal features of the crack expansion. On such a basis, the author, combing the probability distribution hypothesis of the rock strength, studies the critical phenomenon during the process of the rock’s unstable failure with the adoption of renormalization model, and gains the theoretical critical point of the rock material’s unstable failure and the development direction of its stability. Contrasting the experimental data with the calculative results of renormalization model, the author proves that the model can accurately simulate the rock’s unstable failure and effectively predict the critical point of failure, thus, establishes the criterion of the rock’s stability.(2) According to the deformation localization of the rock and the self-organized critical action during the instability failure process, "sandpile cellular automata" model is adopted to study the microscopic self-organized critical behavior such as the crack expansion and damage evolution and energy release during the rock deformation process.(3) A plane strain loading system is developed, then the localized deformation and the instable failure mechanism of Chongqing red mud sandstone under the plane strain condition are investigated by this loading system for the first time. Author studies the elastic wave features during the plane strain loading process, keeps track of the whole evolution process of the rock’s deformation localization, and acquires the initiativepoint of the soft rock’s deformation localization and the critical point of instable failure. Meanwhile, he studies, under the condition of plane strain, the affection of the initiation and evolution of the soft rock’s deformation localization according to the variations of loading speed, water content and slope angle.(4) Adopting advanced laser digital speckle method, the author first conducts the contrasting experiments of deformation localization between the mud sandstone and muddy rock and studies the effects of loading speed on the soft rock’s deformation localization under uniaxial pressure. Through a range of correlation analyses of speckle interference, and the temporal and quantitative pursuit and determination of the variation laws of the soft rock’s deformation localization, he observes the whole "revolving" process of the deformation localization area of the mud sandstone and the muddy rock. Also, he determines the starting moment of localization and quantitatively surveys the width and the deformation speed of the localization area.(5) Based on elastic-plastic constitutive model of the rocks, the author, adopting the sliding block - spring combination system, studies the mechanics model of the shear band and obtains the starting conditions of deformation localization controlled by such a mechanics model.(6) According to the bifurcation theory of material instable failure, the author makes a theoretical study of the soft rock’s deformation localization in order to d更多还原