真三轴应力状态下岩石变形破坏过程细观数值模拟研究

发布时间：2019-04-27 14:47

【摘要】：地下工程岩体均处于真三轴应力环境下,在这种应力环境下岩石的变形破坏特征与常规三轴应力环境有较大差别,而目前对岩石变形破坏过程的研究多基于常规三轴应力状态。因此,研究真三轴应力状态下岩石的变形破坏过程对于揭示地下工程岩体灾变机理具有十分重要的理论意义和指导价值。本文综合运用了数值模拟和室内试验相结合的方法,对真三轴应力状态下岩石的变形破坏过程进行了研究,研究成果如下:(1)运用颗粒流离散元程序PFC~(3D)建立了岩石真三轴数值模型,对其细观参数敏感性进行分析,得出一组符合室内试验的细观参数。(2)基于建立的岩石真三轴数值模型,系统研究了真三轴应力状态下岩石的变形特征、强度特征、损伤特征和破坏特征,重点讨论了岩石变形破坏过程的中间主应力效应,揭示了中间主应力对岩石的变形破坏起先抑制后促进的作用机制。真三轴应力状态下岩石变形破坏过程模拟还表明,宏观裂隙主要发生在中间主应力方向的垂直面上,而在最小主应力方向垂直面上未出现宏观裂隙。(3)运用岩石强度理论对岩石强度特征分析表明,Mogi-Coulomb强度准则能更好的描述真三轴应力状态下岩石强度特性;运用裂纹应变理论对岩石变形破坏特征进行研究,进一步验证了中间主应力效应对岩石破坏演化机制的影响;基于数值模型黏结破坏特征定义了损伤变量,并运用岩石损伤理论建立了真三轴应力状态下的岩石损伤本构模型,揭示了岩石的损伤破坏演化机制。
[Abstract]:The rock mass in underground engineering is in true triaxial stress environment, and the deformation and failure characteristics of rock in this stress environment are quite different from those in conventional triaxial stress environment. At present, the research on deformation and failure process of rock is mostly based on the conventional triaxial stress state. Therefore, it is of great theoretical significance and guiding value to study the deformation and failure process of rock under true triaxial stress for revealing the mechanism of rock mass disaster in underground engineering. In this paper, the deformation and failure process of rock under true triaxial stress is studied by means of numerical simulation and laboratory test. The research results are as follows: (1) the true triaxial numerical model of rock is established by using the particle flow discrete element program PFC~ (3D), and the sensitivity of mesoscopic parameters is analyzed. A set of mesoscopic parameters in accordance with laboratory tests are obtained. (2) based on the established true triaxial numerical model of rock, the deformation, strength, damage and failure characteristics of rock under true triaxial stress are systematically studied. In this paper, the effect of intermediate principal stress on rock deformation and failure is discussed, and the mechanism of action of intermediate principal stress on initial inhibition and promotion of rock deformation failure is revealed. The simulation of rock deformation and failure under true triaxial stress also shows that macro-cracks mainly occur on the vertical plane in the direction of intermediate principal stress. However, there are no macroscopic cracks on the vertical plane of the minimum principal stress. (3) the analysis of rock strength characteristics by using the rock strength theory shows that the Mogi-Coulomb strength criterion can better describe the rock strength characteristics under true triaxial stress condition; The characteristics of rock deformation and failure are studied by means of crack strain theory, and the influence of intermediate principal stress effect on rock failure evolution mechanism is further verified. The damage variables are defined based on the cohesive failure characteristics of the numerical model. The damage constitutive model of rock under true triaxial stress is established by using the rock damage theory, and the damage evolution mechanism of the rock is revealed.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU45

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