The Ground Penetrating radar (GPR) is often used to detect cracks in concrete.In this paper,the finite difference time domain (FDTD) method is used to simulate the crack of concrete by using the Gprmax 2D and Matlab software.The fractures of different types,sizes and different internal fillings are simulated respectively,with the image changes characteristic analyzed and compared.The results showed that there exists the influence of different types of concrete cracks on the propagation of electromagnetic waves,so it has a different influence on the image;the influence of different fillers on the propagation of electromagnetic waves in the cracks is great,because the water has the strong absorption of electromagnetic wave,and the electromagnetic wave reflection is enhanced,resulting in the multiple influence on deep and more complex image features.The forward modeling can provide some scientific basis and guidance for the interpretation of the actual detection results.%地质雷达(GPR)常用于混凝土内部裂隙的检测.本文利用GprMax 2D和Matlab软件对混凝土内部裂隙进行时域有限元差分(FDTD)法正演模拟,分别针对不同类型、不同尺寸和内部不同填充物的裂隙进行模拟,分析对比图像变化特征.结果表明:不同类型的混凝土内部裂隙对电磁波的传播影响不同,从而造成对图像的影响范围不同;裂隙内部不同的填充物对电磁波的传播影响较大,其中水对电磁波有较强的吸收作用,使得电磁波反射增强,造成多次波的影响较深,图像特征较为复杂.通过正演模拟可以为地质雷达实际探测结果的判读提供一定科学依据和指导.
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