【作者】 彭海涛；

【导师】 方志；

【作者基本信息】 湖南大学 ， 桥梁与隧道工程， 2011， 硕士

【摘要】 目前,混凝土外观质量检测一般采用仪器或人工估算的检测方法,该方法检测结果严重依赖检测人员的个人标准和经验,缺乏客观性,难以准确量化结构外观质量的劣化过程;我国混凝土工程量大面广,采用人工的检测方法,费时费力,同时检测过程中环境局限性大且对人员安全要求很高,有经验的检测人员相当缺乏,相应的定量评价体系尚未建立。鉴于人工检测与评定存在的不足,有必要引入以定量分析为主体的较客观的外观质量评定体系。本文基于图像分析技术的应用,提出定量检测混凝土表面裂缝、色差、气孔和孔洞的图像测量方法,采用Matlab编制程序实现,并进行试验研究,以验证所提方法的有效性,最后采用三级模糊综合评估方法建立混凝土外观质量评价体系。主要内容如下:(1)对于裂缝宽度的检测,提出在混凝土表面粘贴纯色标定块来标定、修正原始图像,并对其进行对比增强、平滑等一系列处理后直接在图像上确定最大裂缝宽度的测量方法。试验结果表明:基于正拍图像的裂缝宽度识别精度可达93.4%;基于斜拍图像的识别精度亦可达到90.9%,均可满足实际工程应用的要求。(2)对于色差,提出采用灰度图像的标准差作为评价混凝土外观色差的指标,分析了日照、拍摄距离等因素对标准差的影响,建立了基于梯形模糊分布的混凝土表面色差定量评价方法。试验表明:识别结果和人工视觉识别结果吻合良好。(3)就气孔、孔洞而言,提出一种基于边缘检测与形态学操作相结合的检测方法,采用检测率和准确率来评价方法的有效性。对10幅图进行了试验研究,结果表明:图像的检测率均值92.1%,标准差为5.1%,表明所提方法能较完整地检测出气孔、孔洞的个数,稳定性较好。就准确率而言,均值高达96.4%,标准差仅3.4%,表明该方法准确率较高,识别出的缺陷基本上为真实的缺陷,具有较强的鲁棒性。(4)基于图像分析技术的外观缺陷的定量检测结果,采用三级模糊综合评估方法,建立了混凝土桥梁外观质量评价体系。更多还原

【Abstract】 Currently, manual inspection performed by a qualified inspector is the primary inspection method, the detection results are extremely dependent on individual experiences, lack of objectivity, and difficult to quantify deterioration process accurately. However, concrete engineering structures are widely used in our country, manual inspection of concrete surface is laborious and time-consuming. In addition, the influence of environmental is great in the process of detection and the experienced inspectors are quite deficient, and corresponding quantitative evaluation system has not been established yet. In view of the deficiencies of manual inspection, it is necessary to introduce an appearance quality evaluation system which is more objective and mainly based on quantitative analysis.Based on the application of image analysis technology, this paper presents a novel concrete surface defects detection and assessment approach that can detect concrete surface cracks, discoloration, air-pockets and holes. The program is written in Matlab and performed experimental study to verify the validity of the proposed method. Finally, concrete surface defects detection and assessment system has been established based on three-stage fuzzy comprehensive assessment method. The main investigations are summarized as follows:(1)For the detection of crack width, a new non-contact method was proposed in this paper,which using the calibration block on the concrete surface and revising the original deformed images,then enhancing the contrast of the revised image and smoothing them, etc. Finally, the width of crack in the image can be calculated. The method was verified by the laboratory experiment of a cracked concrete girder using vertical and oblique photographic techniques to detect the cracks and the accuracy can reach 93.4% and 90.9%, repectively, it shows that this new method can effectively detect the width of crack.(2)For discoloration, this paper presents the standard deviation of gray-scale image as evaluation index, and analyzes the influencing relationship of sunshine and shooting distance, and establishes assessment approach of discoloration based on trapezoidal fuzzy distribution. Experimental results show that the recognition results and manual visual assessment results agree well.(3)As to air-pockets and holes on concrete surface, this paper presents a novel method of combination of edge detection and morphological operation. The detection rate and accuracy rate are used to evaluate effectiveness of this method. 10 images are tested, and experimental results show that the average of detection rate is 92.1% with standard deviation of 5.1%, so this method can detect the number of air-pockets and holes completely and have much better stability. The average of accuracy rate is 96.4% with standard deviation of 3.4% only, it shows that the identified air-pockets or holes are almost always true, so this method has strong robustness.(4)Based on the image analysis results of quantitative detection of defects, using three fuzzy synthetic evaluation method, this paper established a quality evaluation system for concrete bridge appearance.更多还原