Abstract Along with the development of urbanization, an increasing number of subsurface voids in urban cities can have serious effects on the expected functionality of key infrastructure elements such are roads. Ground penetrating radar is an effective technique for imaging the subsurface and detecting such air voids. The GPR responses of air voids with different horizontal width were quantitively investigated in this study using forward modelling: empirical experiments in both laboratory and site; as well as numerical simulations with FDTD. Two typical road constructions were modelled: reinforced concrete pavements and bituminous pavements, where the majority of underground utility networks are buried underneath. Pulse GPR signals having two centre frequencies: 600 MHz and 200 MHz were simulated. It was observed that the ratio of void size and GPR signal wavelength would result in various patterns in the GPR B-scans: they can be a hyperbola, a cross pattern, a bowl shape pattern, and a plain reverberation pattern. And GPR responses of voids under road structures were distorted by reinforcement. With signatures of air voids appeared in GPR B-scans through validation by lab experiments and ground truthing, confidence of void identification will be enhanced.

中文翻译：

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地下空气空隙探地雷达响应的正演模拟

摘要 随着城市化的发展，城市中越来越多的地下空隙会对道路等关键基础设施要素的预期功能产生严重影响。探地雷达是一种对地下成像和探测此类空气空隙的有效技术。本研究使用前向模型定量研究了具有不同水平宽度的气隙的 GPR 响应：实验室和现场的经验实验；以及使用 FDTD 进行数值模拟。对两种典型的道路建筑进行了建模：钢筋混凝土路面和沥青路面，其中大部分地下公用事业网络都埋在下面。模拟了具有两个中心频率的脉冲 GPR 信号：600 MHz 和 200 MHz。观察到空隙大小和 GPR 信号波长的比率会导致 GPR B 扫描中的各种模式：它们可以是双曲线、交叉模式、碗状模式和纯混响模式。道路结构下空隙的 GPR 响应被加固扭曲。通过实验室实验和地面实况的验证，在探地雷达 B 扫描中出现空隙的特征，将增强空隙识别的信心。