基于数字图像的混凝土开裂监测和安全评价研究

发布时间：2018-06-19 12:20

本文选题：混凝土结构 + 安全监测　；参考：《华北科技学院》2017年硕士论文

【摘要】：混凝土开裂裂纹检测是建筑结构安全技术十分关注的基本问题之一。本文应用计算机图像技术新近发展起来的数字图像相关测量方法,以混凝土梁弯曲变形为试验对象,提出了基于数字相关的混凝土开裂和安全评价研究。研究工作涉及到数字图像相关方法实验平台设计、分析信号的优化处理、混凝土梁开裂变形的观测实验研究以及混凝土表面裂纹扩展的安全评价研究四个方面的内容,其具体情况如下:(1)提出了数字图像相关测量方法实验平台的设计方案。该设计方案立足良好的分析图像质量、可靠的相关系数描述函数的定义及适用和配套的常规性技术处理环节三个基本技术要点,考虑到了实验室现有技术条件,形成了以普通工业CCD相机为限制性环节的技术实施路线。(2)提出了与普通工业CCD相机采集图像配套的分析图像优化处理技术方法。针对数字图像相关测量分析信号的优化处理,将二维经验模态分解技术用于数字图像相关测量中,对带有噪声的采集图片进行频率由高到低的逐层分解,结合各个层次贡献于图像组成的比例,采用累积贡献率的方法,对各分解层进行滤波处理,实现采集图像除噪的目的。利用平面网格标定的方法对镜头进行矫正,提高了采集图像的质量,矫正方法较好地适应数字图像相关方法测量分析信号优化处理的要求。(3)以混凝土梁弯曲变形为对象,完成了基于数字图像的混凝土开裂变形研究。位移场、应变场的跟踪监测结果表明,数字图像相关方法为混凝土表面开裂变形提供了有效的测试手段,位移分量能准确捕捉到载荷作用下混凝土开裂变形的相关信息,应变分量指明的高应变区确定了裂缝的几何形态与裂缝的具体位置。(4)提出了一种基于数字图像方法的混凝土表面裂纹扩展判别方法。在数字图像相关测量方法的混凝土开裂实验数据对比分析基础上,结合混凝土分段线性简化的强度判据的分析,引入等效应变描述,获得了一个用观测应变分量判断混凝土裂纹扩展的理论关系。理论结果与实验观测结果具有良好的一致性。本文的研究工作为混凝土建筑安全提供了具有针对性的监控技术方法,在实验室所完成的研究结果表明这一技术方法良好的应用推广价值。
[Abstract]:Crack detection of concrete is one of the basic problems in building structure safety technology. In this paper, the digital image correlation measurement method developed by computer image technology is used to study the concrete cracking and safety evaluation based on digital correlation. The bending deformation of concrete beam is taken as the experimental object. The research work involves the design of digital image correlation method experimental platform, the optimal processing of analytical signal, the experimental study of concrete beam cracking and deformation observation, and the safety evaluation of concrete surface crack propagation. The details are as follows: (1) the design scheme of the experimental platform of digital image correlation measurement method is proposed. The design scheme is based on three basic technical points: good analysis of image quality, reliable definition of correlation coefficient description function and its applicability and matching routine technical processing, taking into account the existing technical conditions of the laboratory. In this paper, the technical implementation route of conventional industrial CCD camera is formed. (2) the analysis image optimization processing method matching with conventional industrial CCD camera is put forward in this paper. In order to optimize the signal processing of digital image correlation measurement and analysis, the two-dimensional empirical mode decomposition technique is applied to the digital image correlation measurement, and the frequency of the captured image with noise is decomposed from high to low layer by layer. Combined with the proportion of each level contribution to the image composition, the method of cumulative contribution rate is used to filter each decomposition layer to achieve the purpose of image denoising. The method of plane grid calibration is used to correct the lens, which improves the quality of the collected image. The correction method is better suited to the requirement of signal optimization of measurement and analysis by the digital image correlation method, and takes the bending deformation of concrete beam as the object. The research of concrete cracking and deformation based on digital image is completed. The tracking and monitoring results of displacement field and strain field show that the digital image correlation method can provide an effective testing method for concrete surface cracking and deformation, and the displacement component can accurately capture the relevant information of concrete cracking and deformation under load. The high strain region indicated by the strain component determines the geometric shape of the crack and the concrete location of the crack. (4) A method for judging crack propagation on concrete surface based on digital image method is proposed. On the basis of comparing and analyzing the experimental data of concrete cracking using digital image correlation measurement method and combining with the analysis of concrete strength criterion, the equivalent strain description is introduced. A theoretical relation for judging the crack growth of concrete by observed strain component is obtained. The theoretical results are in good agreement with the experimental results. The research work in this paper provides a targeted monitoring technique for the safety of concrete buildings. The results of the research in the laboratory show that this technique has a good value of application and popularization.
【学位授予单位】：华北科技学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP391.41;TU755.7

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