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混凝土结构缺陷的雷达检测方法研究 总被引:1,自引:0,他引:1
介绍了探地雷达技术在混凝土结构无损检测中的应用原理,针对混凝土结构中钢筋干扰下缺陷雷达图像识别这一难点,制作了无钢筋和有钢筋的缺陷混凝土板,进行对比试验研究,得到了孔洞、裂缝、不密实等缺陷在无钢筋和有钢筋情况下的雷达波图像典型特征并做出识别,同时对注水后裂缝进行针对性试验.并将该方法应用到实际工程缺陷查找中,经取芯验证,雷达图像异常特征与缺陷实际位置吻合较好,取得了良好效果. 相似文献
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为了研究装配式混凝土结构内部缺陷的检测方法,设计制作了含有不同类型缺陷的装配式混凝土结构用叠合构件,并对试件内部缺陷进行了基于阵列超声和电磁波雷达的无损检测方法试验研究。结果表明:阵列超声法检测得到的结果与试件内部缺陷设计情况吻合度较高,通过不同二维断面成像的分析,可有效识别混凝土内部孔洞、夹杂及脱空等缺陷;当缺陷与测试面间不存在钢筋或钢筋处于内部缺陷边缘且缺陷尺寸较大时,采用电磁波雷达法可有效地定位混凝土构件内部缺陷,但对于非金属类夹杂或孔洞可能会出现漏检情况。与阵列超声法相比,水平投影定位精度偏差较大,通过后处理软件得到的水平二维图像内部缺陷位置及大小的准确性也有待进一步提高。研究结果可为装配式混凝土结构质量控制和验收提供参考和依据。 相似文献
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采用冲击回波法、雷达法及超声CT对装配式混凝土结构叠合构件结合面缺陷检测进行试验研究.考虑缺陷深度、类型等参数,共设计制作了4个试验构件.采用IE-Scanner扫描式冲击回波仪、PS1000混凝土透视仪、A1040 MIRA混凝土超声断层扫描仪分别对4个试验构件结合面缺陷进行检测,并通过钻芯进行验证.试验结果表明,冲击回波法和超声CT均能检测叠合构件结合面的缺陷,其中超声CT还能准确定位缺陷的埋置深度,而雷达仅能检测到不位于钢筋下的结合面缺陷.实际叠合构件缺陷检测时,应首先采用扫描式冲击回波仪进行大范围快速检测,初步确定缺陷位置,然后采用超声CT对缺陷大小及埋深进行详细检测. 相似文献
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简要介绍了探地雷达用于检测的基本原理,并通过对预制的混凝土模型进行探地雷达的检测比对,说明了探地雷达对不同缺陷存在的判断效果,进一步指出了探地雷达用于检测的局限性和针对性。 相似文献
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应用地质雷达进行混凝土构件缺陷检测时,浅埋钢筋会对层下钢筋及目标物的探测造成干扰,对其原因进行分析并采取有效的手段去除干扰具有重要意义。通过理论计算设计了检测试验方案,在沙槽中埋设不同埋深钢筋模拟混凝土中钢筋的检测,运用多种偏移手段对检测信号进行处理。结果表明:浅层钢筋对深层钢筋检测的干扰,与地质雷达探测区域覆盖的浅层钢筋的长度有关;相较于绕射叠加偏移、Kirchoff偏移、F-K域偏移等方法,Tau-p域偏移能够更好地对钢筋检测信号进行偏移处理,钢筋的位置被更为准确地识别,偏移后的地质雷达三维图像变得平坦、干净。结合工程实例,对地质雷达数据进行了偏移分析,取得了良好的效果。 相似文献
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Crosshole ground-penetrating radar (GPR) is a widely used measurement technique to help inspect the structural integrity of man-made underground structures, yet the resulting waveform and travel-time data can be difficult, complex and challenging to interpret. Here, we introduce the elements of a Bayesian inversion method for analyzing crosshole GPR data to guide detection of defects (weakness zones) in underground concrete structures. This framework uses as main building blocks the two-dimensional finite-difference time-domain (FDTD) simulator, the discrete cosine transform (DCT) method, and the DREAM(ZS) algorithm to reconstruct the relative permittivity field of an underground concrete structure from full-waveform GPR inversion. The FDTD simulator solves numerically Maxwell's equations in the time and space domain of the crosshole GPR experiment and simulates iteratively the electromagnetic (EM) waveforms. The DCT algorithm transforms the Cartesian parameterization to the frequency domain and reduces drastically the dimensionality of the parameter space by retaining only the low-frequency DCT-coefficients. Markov chain Monte Carlo (MCMC) simulation with the DREAM(ZS) algorithm is used to estimate the posterior distribution of the DCT-coefficients. The usefulness and applicability of the FDTD-DCT-DREAM(ZS) framework is demonstrated on a synthetic test example involving a unit square concrete structure with a small defect. Our results demonstrate that the proposed method successfully detects and locates defects in concrete structures. The inversion results appear rather insensitive to the noise level of the measured GPR waveforms, and the amount of data used (number of receiving antenna positions), as long as a sufficient number of measurements is available. The more DCT-coefficients that are used to characterize the concrete structure, the more accurate the results, yet the larger the posterior uncertainty of the reconstructed permittivity fields. 相似文献
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《Construction and Building Materials》2002,16(3):147-154
A detailed knowledge of the present condition of bridges is essential for the planning of maintenance and rehabilitation. Mobile ground penetrating radar (GPR) systems are efficient tools for obtaining information such as depth of rebar, asphalt pavement thickness and concrete damage beneath the pavement. Non-destructive testing, quasi-continuous results and efficient data acquisition are the main advantages of mobile GPR systems. In this paper, benefits and limitations of mobile GPR systems are discussed using examples from EMPA's recent work. The emphasis is on the investigation of pavement thicknesses and depths of rebar on concrete bridges. 相似文献
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Kimberly Belli Sara Wadia-Fascetti Carey Rappaport 《Computer-Aided Civil and Infrastructure Engineering》2008,23(1):3-16
Abstract: Ground penetrating radar (GPR) has become a viable technology for non-destructive condition assessment of reinforced concrete structures. Interpretation of the radar signal is typically performed through preliminary filtering techniques and interpretation is based on viewing numerous signals in the form of a scan. Although anomalies can be evident in the scanned image, quantification and interpretation of the main issue remain ambiguous. This article presents the ambiguity and common methods of interpretation based on response amplitude and travel time. An integrated medium is developed and used as a forward modeling tool to generate a realistic radar reflection of a reinforced concrete bridge deck with defects. A healthy deck reflection is obtained from a separate model and is combined with an inverse solution to quantifiably estimate unknown subsurface properties such as layer thickness and dielectric constants of subsurface materials evident in the realistic radar trace as well as. The forward modeling tool and associated model based assessment provides an objective computational alternative to the interpretation of scanned images. 相似文献
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混凝土的密实度是混凝土耐久性及抗渗性的一个重要指标.由于探地雷达检测具有无损、检测速度快、扫描面积大、效率高等优点,故作者尝试用探地雷达对混凝土的密实度进行检测.针对三种不同外观质量的混凝土路面,对其密实度进行了雷达扫描检测,发现雷达图像有明显差别.并利用渗水性检测仪,对这些路面的抗渗性作了现场测试.结果表明,两种方法的结论是一致的,这表明探地雷达对混凝土的密实度检测,是一种可行的方法. 相似文献
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探地雷达检测是一种无损检测方法。混凝土建筑结构内部通常都有钢筋网支撑,由于金属介质对高频电磁波存在强反射现象,因此使用探地雷达进行建筑结构检测非常适宜。通过分析探地雷达剖面,可判断建筑结构内部钢筋位置及分布状况。通过钻孔验证,GPR测试结果与污水处理池底部实际情况一致。 相似文献