【作者】 杨锐玲；

【导师】 朱永华；

【作者基本信息】 武汉大学 ， 工程力学， 2004， 硕士

【摘要】 对已建混凝土桥梁、高层建筑、高架道路、水坝的安全评估；解决传统查找混凝土建筑物隐患方法效率低、成本高且不安全问题，实现快且无损探测混凝土裂缝、空洞和高层建筑外墙是否剥离，是国际、国内土木工程界亟待解决的重大课题，有巨大的社会需要和经济效益。但是由于检测环境条件太复杂。现代建筑物的主要材料钢筋混凝土是非均匀的、多孔的、多变的各向异性复合材料，它不仅有着复杂的结构，而且其性质的分散性也极大。故在土木工程中，红外线无损检测技术的应用还不像在其它工业部门那样普遍。本文进行的红外热成像法探测混凝土缺陷的实验及理论研究是国家自然科学基金资助项目“用红外遥感技术快速探测混凝土劣化程度”主要研究内容之一，旨在已有相关成果的基础上，通过理论分析、有限元模拟计算和实验相结合，探讨混凝土缺陷无损检测原理和方法。为此，本文主要进行了以下几个方面的研究工作： 1．根据热辐射定律和混凝土的热传导性能阐述了红外热成象技术无损检测混凝土缺陷的原理和方法。 2．根据热传导方程和热辐射边界条件从理论上建立了计算混凝土内部缺陷深度公式和确立了该公式适用范围及条件。最后给出了截断误差计算公式。 3．利用有限元热分析技术模拟在各种环境条件、缺陷尺寸和试件尺寸下混凝土的传热问题。并利用混凝土表面温度值验算缺陷深度的计算公式。 4．相似理论应用于固体热传导模型实验中，使难于在实验室复现的原型利用相似准则得以实现。对不同定型准则下缺陷深度和大小的进行研究，得出不同定型准则下，不同缺陷深度和大小的试件表面温差ΔT变化曲线图，给出利用曲线图查找缺陷深度和大小的方法。 5．红外线摄像仪摄取的混凝土表面温度场进行计算机分析形成数字温度场。实验结果和有限元解析法结果进行比较．寻求高精度检测方法。 最后，在全面总结论文工作基础上，提出该课题尚待深入研究的问题。更多还原

【Abstract】 In the fields of international and domestic civil engineering, there is an urgent need to research on some important subjects such as to thoroughly assess the constructed concrete bridges, tall buildings, viaducts and dams, to solve the problems of low efficiency, high cost and insecurity caused by traditional check methods in seeking the potential danger of the concrete - constructions, and to quickly carry out loss less exploration in whether the concrete crack and the bare hole will remove from the outside walls of tall buildings. The fulfillment of these subjects will bring enormous social and economical benefit.However, the complication in checking conditions, and the uneven, porous and unstable anisotropic composite materials for the reinforced concrete of modern buildings, which has complex structure and disperse quality, make the infrared loss less checking technique not widespread in civil engineering as in other industrial fields.In this paper, the experiments and theories of using infrared thermal mapping to probe into the concrete defect are given as the main research contents of the "Inspection Method for Evaluating Decaying Concrete Using Thermal Infrared Remote Sensing System" which is subsidized by National Natural Science Foundation. Based on relative results, by combining the finite element imitation computation with experiments together, this paper explores the principles and methods in the loss less checking of concrete defect.The paper mainly deals with the following aspects:1. According to thermal radiation laws and thermal conduction functions of the concrete, the principles and methods by using the infrared thermal mapping technology to carry out loss less inspection for concrete are expounded.2. According to thermal conduction formulation and thermal radiation boundary terms, the formula to calculate the depth of the internal defect in concrete is theoretically put forward and the available range and terms of the formula are established. In addition, the formula for cut-off error is also given.3. The techniques for the finite element thermal analysis are applied to imitate the thermal conduction in concrete at all kinds of defect sizes and object sizes. Furthermore, the formula to calculate the defect depth is also worked out by using concrete surface temperature.4. Similarity theories are applied in the experiment of solid thermal conduction model. As a result, the prototype test difficult to be realized in laboratory is successfully carried out through some similarity principles. By studying the defect depth and size in various types and standards, the variation curve of the defect size is designed in this paper, and the problem on how to use the curve to seek the defect depth and size is solved as well.5. The figure temperature field is formed by analyzing the concrete surface temperature field taken by infrared thermal mapping instrument. The experiment result is also compared with the finite element analytic result so as to search a more accurate measuring method.Finally, by summarizing all the research work, some unsolved problems concerning this subject are proposed.更多还原