基于GprMax的道路空洞探地雷达图像正演模拟

发布时间：2018-12-11 19:50

【摘要】：近年来,我国的道路塌陷事故愈演愈烈,给人民的生命财产安全造成了极大危害。因此,亟待对道路路基下空洞进行检测,提前发现进行治理。由于探地雷达具有高效、无损、分辨率高的特点,且道路结构层及土基和下方潜伏的充气空洞以及充水空洞之间的介电常数差异大,因此探地雷达技术十分适合道路空洞的检测。但是实际应用过程中,由于缺乏探地雷达异常图像评判客观标准,且雷达资料解释具有多解性和主观经验性,导致探地雷达技术在道路地下空洞中的应用难以获得理想效果。因此利用计算机开展空洞正演模拟研究,研究各种典型空洞模型的电磁波传播、成像规律,这对于认识探地雷达实测结果,识别空洞目标体具有实际意义。本文通过建立道路路基下充气与充水空洞模型,基于时域有限差分法,用GprMax及Matlab编程实现道路空洞正演模拟,对空洞模型正演模拟结果的雷达波图像特征进行分析。主要内容如下:(1)针对道路空洞形成特点,将道路空洞分为充气型空洞和充水型空洞,分别进行正演模拟分析,得出判别两种类型空洞的理论依据。(2)针对不同形状、不同深度、不同大小、不同激励源类型、不同激励源中心频率、不同介电常数及电导率条件下进行正演模拟分析,分析不同条件下的雷达波成像特点,电磁波传播规律。(3)最后运用无线探地雷达进行空洞实测实例与正演模拟对比,验证正演模拟的有效性。本文正演模拟结果有助于对实际探测目标体识别和雷达成像资料的解释,为探地雷达在路基空洞检测应用积累理论经验。
[Abstract]:In recent years, road collapse accidents in our country become more and more serious, causing great harm to the safety of people's life and property. Therefore, it is urgent to detect the cavities under the roadbed and to find them in advance. Because GPR has the characteristics of high efficiency, nondestructive, high resolution, and the difference of dielectric constant between the road structure layer, the latent aeration cavity and the water filled cavity in the road structure layer and the underlying soil foundation, Therefore, the GPR technology is very suitable for the detection of road voids. However, in the practical application, due to the lack of objective criteria for the evaluation of ground penetrating radar abnormal images and the multi-solution and subjective experience in the interpretation of radar data, it is difficult to obtain ideal results in the application of ground penetrating radar technology in the underground cavity of the road. Therefore, it is of practical significance to study the electromagnetic wave propagation and imaging law of various typical cavity models by using computer to study the forward simulation of voids, which is of practical significance for recognizing the measured results of ground penetrating radar and identifying the cavity objects. Based on the finite difference time-domain (FDTD) method, the forward simulation of road cavitation is realized by using GprMax and Matlab, and the radar wave image features of the forward simulation result of the cavitation model are analyzed. The main contents are as follows: (1) according to the characteristics of road cavity formation, the road cavity is divided into inflatable cavity and water-filled cavity, and the forward simulation analysis is carried out respectively, and the theoretical basis for distinguishing the two types of voids is obtained. (2) aiming at different shapes, The forward simulation analysis of different depth, different size, different excitation source type, different excitation source center frequency, different dielectric constant and electrical conductivity is carried out, and the characteristics of radar wave imaging under different conditions are analyzed. (3) finally, the effectiveness of forward simulation is verified by using wireless ground penetrating radar (WGPR) to compare the actual cavity with the forward simulation. The results of forward modeling in this paper are helpful to the interpretation of actual target recognition and radar imaging data, and accumulate theoretical experience for the application of ground penetrating radar in subgrade cavity detection.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U416.1

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