【作者】 于庆磊；

【导师】 唐春安；

【作者基本信息】 东北大学 ， 工程力学， 2008， 博士

【摘要】 岩石与混凝土材料的破裂过程一直是力学、材料和工程等学科的研究热点和难点之一。研究岩石类材料的破裂过程,对于评价岩石工程的安全状态,了解岩土工程结构的稳定性及采取合理的支护措施,提高岩石和地下结构工程的设计水平,具有重要的理论意义和工程实用价值。岩石、混凝土类材料在破裂过程中表现出来的宏观力学行为的非线性,源于其细观结构的非均匀性。在基本相同的试验和加载条件下,试件的真实细观结构和内部各种细观介质的力学特性对试件的应力和变形响应起决定作用。因此,进一步研究能有效的测量岩石类材料内部各细观介质空间分布的方法,确定每种介质的本构关系和描述参数,并引入到数值模型中,这样能够更全面、更符合自然规律地研究和观测岩石类材料的力学性能和破坏规律。本文综合了数字图像处理理论、矢量化转化技术和有限元数值计算方法,并结合细观损伤力学理论和强度理论,建立了能比较真实的反映岩石类材料细观结构的破裂过程分析数值模型,并对岩石、混凝土材料细观结构对其断裂破坏力学行为的影响与相关问题进行了研究,主要研究工作总结为以下几个方面：1.分析岩石类材料数字图像在不同颜色空间表现出的图像特征,利用数字图像处理中的图像分割、边缘检测、图像识别等方法实现了对岩石类材料细观结构的数字图像表征。2.借助矢量转化技术,建立了数字图像表征的细观结构与有限元网格模型之间的映射关系；并结合细观损伤力学理论和强度理论,给出细观单元本构关系的损伤力学描述,建立能比较真实的反映材料细观结构的破裂过程分析数值模型。3.采用Visual C++语言,编制了岩石类图像的处理软件DIPS,实现了与有限元之间的模型数据接口,利用Fortan90编制了二维弹性有限元计算模块,并引入数字图像表征的材料非均匀性,在Microsoft Visual C++Studio环境下编制了基于数字图像的岩石类材料破裂过程分析系统RFPA2D-DIP。4.研究了花岗岩细观结构对其力学性能和破裂过程的影响,分析了强度和弹性模量对细观结构的敏感性,进一步揭示单轴压缩载荷作用下,花岗岩轴向劈裂破坏机理,从细观层次分析了花岗岩强度各向异性的产生机理和围压对花岗岩强度、变形和破断角的影响。5.利用边缘检测的数字图像处理方法表征混凝土中界面的形状和分布,并与多阈值分割表征骨料形状与分布方法相结合,实现了对混凝土三相复合细观结构的数字图像表征,研究了骨料的形状与分布对混凝土中应力的分布影响及对裂纹的萌生和扩展的影响。6.在一定的假设条件下,采用连续切片的方法,对材料实体每隔一定的厚度获取其切片图像,采用切片图像表征的细观结构叠加的方法,重建材料的三维细观结构,利用自主开发DIPS软件和岩石破裂分析RFPA3D，建立了比较能真实的反映材料细观结构的三维数值模型,并利用并行计算技术,进了初步应用,研究了界面对加载过程中裂纹扩展的影响。更多还原

【Abstract】 Failure mechanism of rock and concrete materials is the focus and difficulty in mechanics investigations, material and engineering investigations. The investigations on failure process of rocklike materials are very important for evaluating the safe status and stability of geotechnical engineering and structures to take reasonable support measures and improving the designing level in rock engineering and underground engineering.Failure process of rock or concrete materials is a complicated non-equilibrium nonlinear progressive process. The nonlinear characteristic of macro-mechanical behaviors expressed in the process is derived from the heterogeneity of meso-struture. Under the same conditions, the overall stress and deformation of the specimen and the response of internal points are determined by the meso-structure and meso-material’s properties. So how to measure the shape and distribution of meso-materials acutely should be studied. Only if these are integrated into numerical model and the parameters describing the constitutive law are determined, numerical study on mechanical performance and failure mechanism and criterion of geomaterials can be more overall and natural.In this thesis, digital image processing theory, the vector transformation method and the finite element method are integrated and microscopic damage mechanics theory and the theory of strength are synthesized to establish failure process analysis model based on realistic meso-scopic structures and study the realistic failure process of rocklike materials. The work in the present paper can be summarized as follows:1. Image feature of rocklike materials is analyzed in different color space and general-purpose digital image processing methods, including image segment, edge detection, image recognition and so on, are used to complete the characterization of the shape and distribution of meso-materials of rocklike materials.2. The relationship between the meso-structure characterized by digital image processing and the mesh of finite element method is determined in virtue of vector transformation. The damage evolution equations and constitutive law are formulated by integrating microscopic damage mechanics and the theory of strength, and numerical model based on the realistic meso-structure is established.3. Digital image processing software for the image of rocklike materials is developed in Visual C++ language on Microsoft Visual Studio and the data interface for finite element method is realized. Finite element method is applied to obtain the stress and strain of the model. A finite element program is developed in FORTRAN language on PowerStation. Digital image based failure process analysis code for rocklike materials is developed in Visual C++ language in Windows XP operation system by introducing the meso-structure characterized by DIP.4. The effect of meso-structure on mechanical performance and failure process is investigated in detail. The sensitivity of strength and elastic modulus on meso-structure is analyzed and the mechanism of axial splitting fracture subjected to uniaixal compressive load is revealed. The reason for part mechanical effect and the effect of confining pressure on fracture angle are studied.5. Three-phase composite meso-structure of concrete is measured by digital image processing methods combining edge detection and image segment. Edge detection method is used to measure the shape and distribution of interface transition zone and image segment method is used to measure those of aggregate. And further the effect of shape and distribution of aggregate on stress distribution and crack initiation and propagation is studied.6. On some hypothesis, by using serial sectioning method, section images of material are captured at intervals of some depth, and then two-dimensional meso-structure represented by section images is overlapped to reconstruct three-demensional realistic meso-structure of the sample. Three-dimensional numerical model based on realistic meso-structure is established by combining Digital Image Processing Software (abbreviated as DIPS) and three-dimensional rock failure process analysis code (abbreviated as RFPA3D). The effect of interfacial transition zone on crack propagation is primarily investigated by parallel computing technique.更多还原