【作者】 陈文玲；

【导师】 赵法锁；

【作者基本信息】 长安大学 ， 地质工程， 2009， 博士

【摘要】 本文以黑河水库左坝肩的云母石英片岩为研究对象，采用试验研究、理论分析相结合，宏、微观研究相结合的研究方法，基于三轴蠕变试验结果，电子显微镜和偏光显微镜扫描测试结果，对云母石英片岩的蠕变特性、蠕变机理进行了分析，并建立了云母石英片岩的蠕变模型，为边坡变形破坏预测奠定理论基础。首先，对片理发育的软弱变质岩—云母石英片岩，在轴向力与片理垂直的条件下，采用岩石全自动流变伺服仪进行了三轴压缩蠕变试验，对轴向蠕变和径向蠕变进行了对比分析，提出径向蠕变比轴向蠕变敏感，以径向蠕变长期强度作为长期强度更合理。研究了围压对云母石英片岩三轴蠕变的影响，进一步指出围压越大，对径向变形的约束能力越强，径向蠕变长期强度和轴向蠕变长期强度均增加，径向蠕变长期强度与轴向蠕变长期强度的比值减小。在单轴蠕变时，轴向蠕变长期强度可以作为软岩的长期强度。总结出轴向、径向等时应力应变曲线的特点，表明云母石英片岩的蠕变具有明显的非线形特征。总结出三种类型的轴向、径向蠕变速率—时间曲线和对应的三种类型粘滞系数—时间关系曲线。指出现有的蠕变元件组合模型无法描述加速蠕变阶段的根本原因是模型中的粘滞系数没有反映出其实际变化规律。然后，通过偏光显微镜和电子显微镜测试不同蠕变阶段云母石英片岩径轴向的微观结构变化，将云母石英片岩内部分为空隙、裂隙等缺陷、坚硬部分和软弱部分共三部分，提出了张开裂隙的闭合、软弱部分的位置调整、微破裂和坚硬部分的位置调整四种微结构变化，在此基础上，探讨了云母石英片岩的微观蠕变机理，对衰减蠕变阶段、等速蠕变阶段和加速蠕变阶段的微观机理进行了合理解释，并将微观结构变化引起的效应归结为空隙率的变化和损伤效应，通过建立空隙率、损伤变量和宏观应力、应变的关系，间接地建立了宏观力学变量和微观结构变化的关系。接着，建立了云母石英片岩的七元件线性粘弹塑性蠕变模型和非线性粘弹塑性蠕变模型，对轴向蠕变和径向蠕变曲线采用同一模型分别进行了拟合，确定了模型参数，根据试验曲线和拟合曲线的吻合情况，验证了模型的正确性；用各模型参数的平均值作为代表值研究了围压对模型参数的影响，轴向和径向模型参数的区别。总结出由试验曲线拟合求模型参数过程中的影响因素，提出用参数综合辩识法来进行模型参数选择。最后，定义了蠕变损伤变量，该蠕变损伤变量只有2个模型参数，能全面地反映蠕变过程中的四种微结构变化和蠕变机理，简化分解后的蠕变损伤变量能描述在破坏应力下和中高应力下的粘滞系数η₃和时间关系。采用全解耦合的方法来考虑云母石英片岩损伤和蠕变的耦合作用，得到了能反映蠕变机理的云母石英片岩蠕变损伤本构方程，对模型进行了验证，确定了模型参数，并进行了参数敏感性分析。更多还原

【Abstract】 In this paper, aimed at mica-quartzose schist at left dam abutment of heihe reservoir, by using the study method that test study combined with theoretical analysis, macro-scope study combined with micro-scope study, the creep characteristics and creep mechanism of mica-quartzose sschist are analyzed, the creep constitution models are alse established on the basis of triaxial creep tests, polarization microscope analysis and scanning electron microscope analysis.Firstly, triaxial compression creep tests with mica-quartzose schist which is a kind of soft metamorphic rock with lots of schistosity surfaces were carried out on the rock servo-controlling rheology testing machine under the condition of the axial stress vertical to the direction of the schistosity surface. Axial creep characteristics of mica-quartzose schist were analyzed by comparing with radial creep characteristics. It was proposed that, for the mica-quartzose schist, taking the long-term strength of radial creep as the long-term strength was more reasonable since the radial creep is more sensitive than the axial creep. Besides, the higher confining compression is, the stronger the restrain of compression was to radial deformation, which resulted in increase of both the long-term strength of radial creep and the long-term strength axial creep. However, the ratio of the long-term strength of radial creep to the long-term strength axial creep reduces with increased confining compression, therefore, the long-term strength of axial creep can be taken as the long-term strength when studying the uniaxial creep characteristics. The test results alse show that the schistosity surfaces have little influence on the creep characteristic of mica-quartzose schist and it can not control the creep of mica-quartzose. The characteristics of radial isochrounous stress-strain curve and axial isochrounous stress-strain curve are concluded, which shows that the creep of mica-quartzose schist has apparent nonlinesrity. Three kinds of axial creep rate-time surves and radial creep rate-time curves with the related three kinds of viscous coefficient-time curves have been summarized as well, furthermore, it proposes that the radical reasons of the component-combined creep model can not describe the speedup creep phase are that they can not reflect the true variation regularity of viscosity coefficient.Secondly, mica-quartzose schist is separated as defaults such as pores and cracks, relative rigid part and relative rigid soft which are altogether three parts on the basis of polarization microscope analysis and scanning electron microscope analysis of both axial and radial strip of mica-quartzose schist at different creep stage, at the same time, four kinds of microstructure change which are the close of open crack, the situation change of relative rigid part, the situation change of relative soft part and micro-cracking are put forward. Micro-creep mechanism of mica-quartzose schist is investigated, the reasonable interpretations of micro-mechanism on the initial attenuation creep phase , the stabilization creep phase and the speedup creep phase are put forward. The influence of microstructure change on mica-quartzose schist are summarized as the damage effect and the change of porosity, the relation between the macro-mechanics variable and microstructure change is established indirectly through establishing the relation of macro-stress and macro-strain with porosity and damage variable.Thirdly, seven-component linear viscoelastoplastic creep model and nonlinear viscoelastoplastic creep model of mica-quartzose schist are established. By using a same model, the model parameters of axial creep and radial creep are fitted in accordance with test curves and the comparison between the test curves and fitted curves shows that the creep model is right and reasonable. The influence of compression to model parameters and the different between axial model parameters and radial model parameters are also studied by comparing the average of every model parameters. The factors which influence the model parameters during in the course of fitting are summarized, and a comprehensive identification method to select model parameters is put forward.Finally, a creep damage variable which has two model parameters and can reflect both the creep mechanism and four microstructure change of creep is defined. After simplified and separated, this creep damage variable can reflect the change of viscosity coefficientη₃ with time not only under destroyed stress level but also under middle and high stress level. A damage creep constitutional model is obtained by considering the effect of damage and creep, and the comparison between the test curves and fitted curves shows that the creep model is right and reasonable. The model parameters are also determined, and the sensitivity of model parameters is analyzed.更多还原