基于X-ray CT沥青混合料细观结构及力学性能研究

发布时间：2018-01-14 06:14

本文关键词：基于X-ray CT沥青混合料细观结构及力学性能研究　出处：《哈尔滨工业大学》2014年硕士论文　论文类型：学位论文

【摘要】：当前的沥青混合料设计法基本上仍是沿用传统的实验-观察的现象学经验方法，传统研究方法虽为世界道路行业的进步做出了巨大贡献，但现在已经逐渐无法满足工程需要。究其原因，传统方法未从根本上揭示沥青混合料内部结构特征对宏观性能的影响关系，从而出现了统计指标（诸如级配、沥青用量、空隙率等）相同而各试件性能有较大差异的情况。随着交叉学科在路面工程中的不断渗透和研究手段的不断丰富，，越来越多的学者开始致力于研究沥青混合料细观分布规律（颗粒及空隙空间分布）、沥青与集料微观交互作用能力及其对混合料宏观性能的影响，并取得了大量有价值的研究成果。本文针对沥青混合料细观结构与其力学性能的相关性问题开展研究，建立基于X-ray CT断层扫描技术及数字图像处理技术的沥青混合料细观组成、结构分布特征指标体系，建立分析沥青混合料细观组成、结构的定性及定量方法，描述沥青混合料骨架结构形式，及其与力学性能的相关性，克服以往宏观研究的限制，从细观尺度上进行剖析。本文主要的研究内容及成果概括如下：首先，基于德国Phoenix v|tome|x s微焦点工业CT扫描系统，寻求不同情况下沥青混合料试件的最优扫描参数配置；采用“等效体积”法，通过对“标准物质”的扫描并进行空隙体积计算，验证CT体积重构的准确性。在最佳参数配置下，进行差异性物质的分离，为后续分析奠定基础。其次，采用X-ray CT无损扫描对不同级配类型（AC-16、SMA-16、OGFC-16）、成型方式（Marshall击实与SGC旋转压实）、不同压实度下沥青混合料试件进行扫描，利用VGStudio MAX2.2软件研究了空隙在沥青混合料中横向、纵向的分布规律，揭示了空隙在沥青混合料中的不均匀分布的特性。随后，采用数字图像处理技术，利用Matlab程序平台，对二维图像的集料的形态特性以及集料组成分布特性进行分析，并采用统计模型对其分布进行拟合；结合数学中的分形理论，对不同级配、不同成型方式及不同压实度下的沥青混合料试件的连续截面几何信息进行了研究。再次，对于沥青混合料的骨架特性，分别从宏观、细观进行分析对比；采用Matlab图像处理模块，结合散体力学理论，通过对集料骨架接触算法进行设计，对沿高度方向的集料接触点数量进行统计分析。最后，建立了沥青混合料内部细观结构与其宏观力学性能之间的联系。采用劈裂试验方法评价力学性能，并采用数字散斑DIC技术对不同细观结构下的试件破坏模式与应变场的均匀性进行分析；并利用PFC-2D软件对不同结构类型沥青混合料进行受力模拟，验证骨架接触的重要性；结合灰关联理论，分析了细观指标对其力学性能影响程度的敏感性。
[Abstract]:The current asphalt mixture design method is still using the traditional experiment-observation phenomenological experience method, although the traditional research method has made great contribution to the progress of the world road industry. But now it has been unable to meet the needs of the project. The traditional method has not fundamentally revealed the impact of the internal structural characteristics of asphalt mixture on the macro-performance of the relationship, thus the emergence of statistical indicators (such as gradation. With the continuous penetration of cross-disciplinary in pavement engineering and the continuous enrichment of research means, the asphalt content, porosity, etc.) are the same and the performance of each specimen has great difference. More and more scholars have begun to study the micro-distribution of asphalt mixture (particle and void space distribution, asphalt and aggregate micro-interaction ability and its impact on the macro performance of the mixture. A large number of valuable research results have been obtained. In this paper, the relationship between the microstructure of asphalt mixture and its mechanical properties is studied, and the microstructure of asphalt mixture based on X-ray CT tomography and digital image processing is established. The index system of structural distribution characteristics is established to analyze the mesoscopic composition of asphalt mixture, the qualitative and quantitative methods of structure, and to describe the structure form of asphalt mixture skeleton and its correlation with mechanical properties. In order to overcome the limitations of previous macro research and analyze from the meso scale, the main contents and achievements of this paper are summarized as follows: Firstly, based on Phoenix v tome x s microfocus industrial CT scanning system in Germany, the optimal scanning parameter configuration of asphalt mixture specimen under different conditions is sought. The accuracy of CT volume reconstruction was verified by "equivalent volume" method by scanning the "standard material" and calculating the void volume. Under the optimal parameter configuration, the difference material was separated. To lay a foundation for subsequent analysis. Secondly, X-ray CT nondestructive scanning was used to compare the different grading types of AC-16 SMA-16 / OGFC-16). The molding method is SGC compaction and SGC rotary compaction, and the asphalt mixture specimens are scanned under different compaction degrees. The transverse and longitudinal distribution of void in asphalt mixture is studied by VGStudio MAX2.2 software, and the characteristics of uneven distribution of void in asphalt mixture are revealed. Then, using the digital image processing technology and the Matlab program platform, the morphology characteristics and the aggregate composition distribution characteristics of the two-dimensional image are analyzed. The statistical model is used to fit the distribution. Based on the fractal theory in mathematics, the geometric information of continuous section of asphalt mixture specimens with different gradation, different molding methods and different compaction degree is studied. Thirdly, the skeleton characteristics of asphalt mixture are analyzed and compared from macro and meso. By using Matlab image processing module and the theory of bulk mechanics, the contact algorithm of aggregate skeleton is designed, and the number of aggregate contact points along the height is analyzed statistically. Finally, the relationship between the internal meso-structure of asphalt mixture and its macroscopic mechanical properties is established. The splitting test method is used to evaluate the mechanical properties. Digital speckle DIC technique is used to analyze the failure mode and the uniformity of strain field of specimens with different mesoscopic structures. PFC-2D software is used to simulate the stress of different structural types of asphalt mixture to verify the importance of skeleton contact. Based on the grey correlation theory, the sensitivity of meso-index to its mechanical properties is analyzed.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U414

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