基于扩展有限元的岩体中裂纹扩展规律研究

发布时间：2018-08-29 09:53

【摘要】：岩体因在地质历史形成过程中会发生岩化，并且受到各种构造力和流体压力的作用，其本身是存在很多天然节理裂隙等缺陷的。当天然作用的应力、应变和流体压力引起岩体破坏的时候，岩体就发生脆性或半脆性断裂。本文基于扩展有限元理论，借助商业软件ABAQUS强大的功能分析了岩石内含预制裂纹情况时裂纹的萌生、扩展、贯通以致试样最后的破坏模式。并以此对比试验成果然后将其应用于工程分析中，为工程实践提供一定的理论基础。总结本文中的主要内容如下： ①对国内外岩石断裂力学的研究进程进行了阐述，分别对有限元方法、无网格方法、数值流形方法和扩展有限元方法在研究裂纹扩展方向的理论方法和进程进行了分析和对比。 ②总结了岩石断裂力学相关理论基础和扩展有限元理论，说明了abaqus基于扩展有限元理论在研究裂纹扩展问题时使用的技术手段，分析了岩石断裂力学在岩石裂纹方面的应用知识，主要包括断裂判据、裂纹类别和应力强度因子算法。 ③通过数值分析软件abaqus模拟不同裂纹倾角和不同裂纹外端距的裂纹萌生、扩展和贯通模式，，其中包括裂纹倾角为30°和45°时裂纹外端距分别为0mm、10mm和20mm六种不同情况的模型破坏模式。并且对比相应每一种相似模型试验成果，以确认数值结果和试验成果的可靠性；在数值模拟结果中，可以更加直观地了解到不同角度不同裂纹外端距裂纹的不同萌生方式，不同扩展模式以及最终的破坏形式。 ④建立双轴压缩数值模型进行演算分析，不仅从裂纹的萌生、扩展和贯通模式方面分析模型的破坏，还分析了双轴压缩模型破坏时模型的应力分布，以此着手从应力分布场差异性分析裂纹扩展的影响。 ⑤根据收集的锦屏二级水电站资料，基于ABAQUS平台建立数值模型以此分析裂纹在该工程中的影响，分析了不同卸载阶段洞周裂纹萌生与扩展情况，以及最终完全应力释放阶段洞周的应力位移分布场与裂纹布置的关系，为工程应用提供一定的依据。
[Abstract]:Rock mass has many defects, such as natural joints and fractures, because of its lithotization during the formation of geological history, and it is affected by various tectonic forces and fluid pressures. When natural stress, strain and fluid pressure cause rock mass failure, brittle or semi-brittle fracture occurs. Based on the extended finite element theory and the powerful function of commercial software ABAQUS, the crack initiation, propagation and penetration in rock with precast cracks are analyzed in this paper. The experimental results are compared and applied to engineering analysis, which provides a theoretical basis for engineering practice. The main contents of this paper are summarized as follows: 1 the research process of rock fracture mechanics at home and abroad is expounded, the finite element method, the meshless method, respectively. The numerical manifold method and the extended finite element method are analyzed and compared in the theoretical methods and processes of studying the crack propagation direction. 2 the related theories of rock fracture mechanics and the extended finite element theory are summarized. This paper explains the technical means used by abaqus in studying crack propagation based on the theory of propagating finite element, and analyzes the application knowledge of rock fracture mechanics in rock crack, mainly including fracture criterion. The numerical analysis software abaqus is used to simulate the crack initiation, propagation and penetration mode with different crack inclination and outer end distance. It includes six different failure modes of crack with 30 掳and 45 掳crack dip angle, respectively, where the outer end distance of the crack is 0 mm / 10 mm and 20mm is different. In order to confirm the reliability of the numerical results and the experimental results, the different initiation modes of cracks with different angles and outer distance can be more intuitively understood in the numerical simulation results. Different propagation modes and ultimate failure modes. (4) the numerical model of biaxial compression is established to analyze the failure of the model not only from the aspects of crack initiation, propagation and penetration mode, but also from the point of view of crack initiation, propagation and failure mode. The stress distribution of the model during the failure of the biaxial compression model is also analyzed, so as to analyze the influence of crack growth from the stress distribution field difference. 5. According to the data collected from Jinping II Hydropower Station, A numerical model based on ABAQUS platform is established to analyze the influence of cracks on the project, and the crack initiation and propagation around the hole in different unloading stages are analyzed. The relationship between the stress and displacement distribution field around the hole and the crack arrangement in the final complete stress release stage provides a basis for engineering application.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU45

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