【作者】 赵国文；

【导师】 向阳；

【作者基本信息】 武汉理工大学 ， 轮机工程， 2002， 硕士

【摘要】 混凝土结构物的缺陷的无损检测是一个非常重要而又非常困难的研究课题，本论文在大量参阅了国内外关于混凝土结构物无损检测的研究资料后，结合本实验室的具体条件，应用冲击反射法集中对应力波在混凝土板块内传播速度和混凝土结构物内部开口裂纹深度的测量等一系列问题展开了研究。 首先，综合分析了国内外关于混凝土结构物的无损检测特别是应用冲击反射法检测混凝土结构物缺陷的研究现状后，了解了目前存在的问题，明确了研究课题的方向和内容。 接着，根据冲击反射法检测结构物缺陷的原理，以路面和桥面的开口裂纹为研究对象，制作了带有不同深度开口裂纹的混凝土板块，使用Sansalone等人开发的冲击反射法实验系统，用单传感器和双传感器分别对混凝土板块内应力波传播的速度和不同深度的开口裂纹进行了测量，得到了重要的实验数据。 其次，对测量数据进行了误差分析，结果表明：(1)传感器及敲击点的位置对实验结果有一定的影响，当开口裂纹的深度较深时，传感器和敲击点的位置应该离裂纹较远；(2)当开口裂纹深度接近50毫米时，由于实验中所使用的小球产生的R波传播深度均超过50毫米，故很难测量出其开口裂纹的深度；(3)实验发现，小钢球直径的大小对裂纹深度的测量结果影响并不是很大，但是，波的开始上升和下降点的测量精度(即两信号的时间延迟)，对测量的结果有很大的影响。 再次，由于两信号的时间延迟对测量结果有很大的影响，因而研究了用互相关时间延迟估计、相位谱时间延迟估计和高阶谱时间延迟估计的方法对测量数据进行了时间延迟估计，结果表明，三种时间延迟估计方法在各自适应的环境下使用，都能得到比较准确的时间延迟估计值。 最后，基于Windows2000操作平台，用MATLAB6.1语言编制了冲击反射法测量系统的软件包。此测量系统能具有用单传感器测量波速、用双传感器测量波速、用双传感器测量混凝土板块开口裂纹的深度和测量公路路面的厚度等功能。整个系统具有友好的人机界面，操作简单，计算快捷，结果的显示直观。更多还原

【Abstract】 Nondestructive testing is a very important and difficult research lesson about the defect of concrete structures. This paper mainly measures the stress waves conveying in concrete structures and the depth of surface-opening cracks in concrete plates by using impact echo method after carefully reading a lot of articles about the state and the abroad of concrete nondestructive in the field and incorporating the special conditions on the laboratory.Firstly, this paper synthetically introduces the state and the abroad of concrete structures about nondestructive testing, in particular examining flaws in concrete structures by using impact echo method, gets at the problem existing at present and clarifies the direction and the content of research lesson in the field.Secondly, according to the theory of impact echo method examining flaws, the road surface and the bridge surface are aimed as study targets, four concrete plates are made with differently deep surface-opening cracks. Using the experimental system of impact echo method made by Sansalone etc., this paper measures the stress waves velocity conveying in concrete plates by using one transducer or two transducers, and measures the depth of surface-opening cracks in concrete plates by using two transducers, and then the important data are attained.Thirdly, through assaying the error generated during measuring data, the result manifests: 1) The location installed of the transducer and the point thumped affects the experiment result to some extent. If surface-opening cracks is deeper, the location of the transducers installed and the point thumped should be further away from the location of surface-opening cracks. 2) When the depth of surface-opening cracks is near to 50mm, it is very difficult to measure the depth of surface-opening cracks because the depth of R_wave conveying in concrete plates from the different small ball bringing forth exceeds 50mm.3) It is clear from the experiment result, the influence isn’t big for the diameters of small balls to measure the data while the time interval between two transducers touched firstly has very big influence on the result.Fourthly, respectively using cross correlation method for estimation of time delay, phase spectrum method for estimation of time delay and high order spectrum method for estimation of time delay, this paper measures time delay estimation of the data obtained because time delay between two signals has big importance on thetesting result. Through comparing three results, accurate time delay is obtained under their own different circumstances.At last, base on the Windows2000 operation system, the soft wrap of impact echo examining system is explored by using the language Matlab6.1.The soft can achieve some function, including calculating the velocity of P_wave in concrete plates by using one transducer or two transducers, amounting the depth of surface-opening cracks in concrete plates by using two transducers and measuring the depth of highway. The whole system has friendly human_computer interface. It is easy for the users to operate, it is straight and quick for the users to calculate and it is clear for the users to observe.更多还原