Nondestructive evaluation of air voids in concrete structures using microwave radar technique
Nondestructive evaluation of air voids in concrete structures using microwave radar technique
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DOI：
10.1080/18824889.2021.2019968
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发表时间：
2022-02
期刊：
影响因子：
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通讯作者：
J. Takayama;Yuki Ohara;Wei Sun
中科院分区：
文献类型：
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作者：
J. Takayama;Yuki Ohara;Wei Sun
混凝土结构的内部无损检测技术是保证混凝土结构安全或健康的必要手段，而内部无损检测技术中的一个重要问题就是能否检测出稀薄的空气空洞或裂缝。本文提出了一种基于微波雷达技术的空泡种类判别和空泡厚度估算方法。具体来说，为了区分空腔和其他物体，利用时频分析分析了微波的相移。此外，基于简单的平行入射模型，对均匀层的微波反射和折射进行了分析，并计算了反射率与空隙厚度之间的特殊关系。实验结果表明，该函数对空气空洞的识别性能较好，但对厚度的定量估计失败。为此，我们提出了一种基于光线追踪传播的复杂传播路径模型，该模型提供了几种传播路径。此外，还考虑了微波的衰减特性。将定量厚度估计方法应用于实验观测波形。估计精度提高约54%，验证了定量厚度估计的有效性。
Nondestructive inner inspection techniques are essential to certify the safety or health of concrete structures, and one of the important issues in these inspections is the detectability of thin air voids or cracks. In this study, we propose a novel method for discriminating the variety and estimating the thickness of air voids based on the microwave radar technique. Specifically, to distinguish air voids from other objects, the phase shift of the microwaves was analysed using time-frequency analysis. In addition, based on a simple parallel incidence model, microwave reflection and refraction analysis were conducted on homogeneous layers, and a particular relation was calculated between the reflectance and the air void thickness. The experimental performance of the functions to distinguish air voids was good, however, quantitative thickness estimation failed. Therefore, we introduced a novel sophisticated propagation path model based on ray-traced propagation, which provides a couple of propagation paths. Additionally, the attenuation feature of microwaves was also considered. A quantitative thickness estimation method was re-applied to the experimentally observed waveforms. The estimation accuracy improved by approximately 54%, and the validity of quantitative thickness estimation was confirmed.