【作者】 徐勇；

【导师】 周志祥；

【作者基本信息】 西南交通大学 ， 桥梁与隧道工程， 2013， 博士

【摘要】 混凝土桥梁的性能退化及失效通常始于裂缝的发生和发展,因此对混凝土结构关键区域的裂缝监测是桥梁健康监测的重要内容,该文依托国家自然科学基金项目“混凝土桥梁结构的机敏网仿生裂缝监测方法研究”(项目编号：50808188)和西部交通建设科技项目“混凝土桥梁裂缝仿生监测系统研发”(项目编号：2009318814065),对混凝土桥梁限宽裂缝机敏网监测方法与应用开展了系统的试验和理论研究,主要研究内容和成果如下：1.裂缝宽度是评定混凝土结构状况的一个重要指标,综合分析国内外公路混凝土桥梁所处环境状况及其裂缝宽度限值,提出特征裂缝宽度指标可分别确定为开裂及裂缝宽度为0.10mm、0.15mm、0.20mm、0.25mm、0.3mm.基于动物肌肤对创伤的感知机理,根据特征裂缝宽度监测需求,研发了在混凝土结构表面黏贴由不同直径的机敏丝构成机敏丝组的裂缝监测机敏网,达到既能监测混凝土表面裂缝的发生发展,又能感知裂缝宽度所在范围值。2.针对表面粘贴有机敏丝的混凝土结构,提出一种由混凝土、粘结胶、机敏丝构成的层合复合材料理论模型,借助McCartney模型分析方法,研究了混凝土开裂后机敏丝断裂瞬间层合结构的应力、应变等物理量,建立了能间接反映机敏丝直径与其断裂时裂缝宽度关系的各层位移、应力、应变等的统一场量微分方程。3.完成了239个表面粘贴有不同直径机敏丝的钢筋混凝土小型试件的加载试验,获得了直径分别为0.05mm、0.06mm、0.07mm、0.08mm、0.13mm和0.20mm机敏丝被崩断时的1600余组裂缝宽度数据；完成了3片表面粘贴有四种直径机敏丝组成的机敏丝组的钢筋混凝土梁加载试验,获得了直径分别为0.05mm、0.08mm、0.13mm和0.20mm机敏丝被崩断时的200余组裂缝宽度数据；应用多项分布的卡方(χ2一)检验方法和最大熵方法(Maximum Entropy Method)对试验数据进行分析处理,结果表明各直径的机敏丝被崩断时的裂缝宽度均满足正态分布规律；机敏丝直径越大,被崩断时对应的裂缝宽度越大。4.针对钢筋混凝土小型试件和钢筋混凝土试验梁,分析比较了不同直径的机敏丝被崩断时对应裂缝宽度的试验数据,结果表明同直径的机敏丝断裂时对应的裂缝宽度的均值、标准差基本相同,说明断裂时机敏丝直径主要与所跨越的裂缝宽度有关,而与被监测试件大小无关;两批次试验中各直径的机敏丝断裂时对应裂缝宽度的实测统计值与依据本文建立的层合复合材料理论模型得到的数值计算结果基本相同,验证了本文层合复合材料理论模型的正确性；根据两批次试验数据统计分析和理论计算结果,得到直径分别为0.05mm、0.06mm、0.07mm、0.08mm、0.13mm和0.20mm机敏丝断裂时对应的裂缝宽度分别为0.07mm、0.08mm、0.09mm、0.10mm、0.18mm和0.25mm,据此建立了不同直径机敏丝被崩断时对应的裂缝宽度计算公式w=1.2456d+0.0058。5.构造了限宽裂缝机敏网监测方法的总体系统,该系统由传感器模块、数据采集模块、数据处理模块、控制模块和数据通信模块五个模块组成。在系统硬件方面针对限宽裂缝监测重点研究并开发出了机敏网传感器和中间处理器；在软件方面研究编制了相应上位机主控程序、下位机采集程序、裂缝仿真程序和系统数据库管理程序。6.针对大跨径斜拉桥混凝土索塔内外表面的裂缝监测要求和实际监测环境,为监测混凝土索塔开裂与否、裂缝宽度是否超过0.20mmm或0.25mm,设计了由0.05mm、0.13mm和0.20mm三种直径构成的机敏丝组监测网,研制了相应硬件和软件系统；在该桥混凝土索塔上安装了限宽裂缝监测系统,实现了及时感知混凝土索塔结构表面新裂缝的出现和原有裂缝的发展情况；多次派专人到现场核查的结果表明本系统监测到的裂缝发展及宽度情况与现场核查基本吻合。更多还原

【Abstract】 The appearance and development of cracks are the most common source of structure degradation and failure in concrete bridges. Crack monitoring in the pivotal area of concrete bridge structure is an important subject of concrete bridge health monitoring. Sponsored by the National Natural Science Foundation of China funded project:"Research on Smart Film Monitoring Method for Cracks of Concrete Bridge Structure"(No.50808188) and the West Transportation Construction Technology Project:"Development of Bionic Monitoring System for Cracks of Concrete Bridge Structure"(No.2009318814065), a comprehensive theoretical research on the method of bionic monitoring for width-limited cracks in concrete bridge structure is conducted, and the project application was constructed subsequently. The main research contents and results are as follows:1. Crak width is the most important parameter in evaluating the safe-state of concrete structure. In the present paper, the charateristic crack width were specified as cracking and a series of sequential crack width(0.10mm,0.15mm,0.20mm,0.25mm,0.3mm) based on analysis of various criterion in limit of crack width and envirment of concrete bridges in freeway system. By simulating the functions of biological sensory neurons to perceive wounds, and meeting the demands of monitoring charateristic crack width, a method both monitoring the appearance and width of crack was proposed by means of pasting smart sensing wire on the surface of concrete bridge structure.2. In this paper, theoretical model of a laminated-composite material is developed upon that the composite material consists of three subsequent layers:concrete, cohesive and smart sensing wire. The McCartney method is employed to analyze the stress and strain of laminated structure at the moment of fracture of smart sensing wire after cracking of concrete. Unified parameter differential equation in terms of displacement, stress and strain of three layers is fomulated, which can indirectly reflect the relationship between diameter of smart sensing wire and crack width when the wire is fastened to fracture.3. Over1600sets of data were obtained from239concrete specimen trial tests, those specimens were pasted with different specifications smart sensing wire in diameter of0.05mm,0.06mm,0.07mm,0.08mm,0.13mm and0.20mm respectively. Over200sets of data aquired from three concrete beams trial tests, those beams pasted with smart sensing wire in diameter of0.05mm,0.08mm,0.13mm and0.20mm. The X2-Checking Mothed and Maximum Entropy Theory are employed to process those data from trial tests. The results show that he crack width is snapped to the Normal Distribution Law when the smat sensing wires were tightened to failure.4. The comparison between the result of small specimens and the result of beams shows that cracks have similar average width and standard deviations when smart sensing wires with the same diameter were tightened to failure. The result also illustrated that the diameter of smart sensing wire is related to crack width, apart from the size of specimen, when them were tightened to failure. Furthermore, the statistic experimental data of crack width from specimens and beams validated the theoretical model of the laminated-composite material. According to the statistic data from two series of experimental and the theoretical calculation results, smart sensing wire with a diameter of0.05mm,0.06mm,0.07mm,0.08mm,0.13mm and0.20mm is corresponding to crack width0.07mm,0.08mm,0.09mm,0.10mm,0.18mm and0.25mm, respectively, and the relationship between failure width and diameter can be fomulated as w=1.2456d+0.0058.5. The width-limited crack bionic monitoring system for concrete bridge structure was built, which comprises five modules:the sensor module, data acquisition module, data processing module, control module and data communication module. In hardware aspects, this paper focused on design and manufacture of alert network sensor and the intermediate processor. In system software aspect, various applications designed for achieving the function of each module were built.6. In order to monitor the crack development and width (its limitation is0.20mm or0.25mm) on the surface of cable tower of long-span cable-stayed bridge, a monitoring network system was developed upon smart film method with smart sensing wires in diameters of0.05mm,0.13mm and0.20mm. The corresponding hardware and software are constructed to complete the monitoring network system. The developed monitoring system is validated by engineering application, which verified the capability and reliability of this system in monitoring appearance and development of craks on the surface of cable tower.更多还原