【作者】 李婷；

【导师】 刘策；

【作者基本信息】 长安大学 ， 交通信息工程及控制， 2014， 博士

【摘要】 探地雷达作为一个快速、高效、无破损的探测工具，已经广泛应用于道路工程无损检测中。通过对实测探地雷达信号进行反演分析，可以对路面结构层厚度、介电参数、含水量以及是否存在脱空等结构病害做出判断。进行反演分析的关键就是构建探地雷达电磁波在层状有耗介质中传播的正演模型和寻找高效的反演优化算法。本文针对目前探地雷达正反演算法中存在的一些问题，提出了基于传输线算法的正演模型以及基于1D-TLM剥层反演的反演策略，该方法对探地雷达基础理论与应用技术的发展具有一定推动作用。取得的主要成果和结论如下：（1）基于TLM方法建立了探地雷达电磁波在层状有耗介质中的传播模型。将FDTD算法中的PML边界条件引入到TLM方法中，依据该模型模拟合成了层状结构体中探地雷达的反射信号，通过与FDTD算法模拟结果进行对比，验证了算法模型的有效性和精确性。（2）从反演问题的本质出发，将1D-TLM模型方法与剥层法相结合，建立了基于1D-TLM的模型参数调整算法。（3）运用谱估计技术对仿真信号和探地雷达实际信号进行了处理，仿真和实验结果表明MUSIC方法得到的信号功率谱曲线可以准确的估计出信号中所含正弦波的个数及其频率，MUSIC与最小二乘法的结合算法能够估计出各信号的幅值分量和相位参数，达到对实际信号进行噪声处理的目的。（4）将雷达信号预处理技术与基于TLM的正反演算法结合起来成功用于实际层状路面结构分析，实验结果表明本文算法可以用于实际层状结构处理，得到反演结果误差控制在了8%内，能够满足工程精度需要；利用探地雷达方法讨论了标准砂含水量与介电常数的关系，根据实际实验数据重新拟合了Topp公式和Alharathi公式，进一步验证了探地雷达方法检测层状结构层含水量的实用性。更多还原

【Abstract】 Ground penetrating radar(GPR),as a kind of fast, effective and non-destructive tool, hasbeen extensively applied to non-destructive testing of road quality. The thickness, watercontent, dielectric properties of structural layers and the void existing in pavement structurecan be obtained using to inverse-analysis of real GPR signals, Construction of forward modelof GPR wave propagation in layered structure and the choice of high efficient optimizationalgorithm are keys for the inverse-analysis. In this dissertation, aiming at improvement ofspeed and accuracy in the forward and inverse algorithms of ground penetrating radar, theforward model based on Transmission Line Matrix (TLM) method and the inverse-analysisbased on1D-TLM stripping layer method is presented. The methods will help in thedevelopment of GPR theory and applications. The main achievements and conclusions of thispaper are summarized below:(1) The model of GPR electromagnetic wave propagating in lossy layered media hasbeen constructed based on Transmission Line Matrix(TLM) method. The simulated signalsreflected from multi-layered structure are obtained by TLM method with the perfectlymatched layer boundary condition, and then compared with that obtained by FDTD method.The comparison results indicate that the forward model is accurate and adaptive forsimulation of GPR wave propagation in layered media structure.(2) Starting from the essence of the inverse problem, the parameter adjustment algorithmis presented based on the layer stripping method and TLM model.(3) Simulated signals and practical radar signals are processed by spectrum estimationtechnology. The results of simulations and experiments shows that signal’s power spectrumwhich obtained by the MUSIC method can accurately estimate the number and frequency ofsinusoidal signals, and the amplitude and phase can be calculated by using the MUSICmethod cooperated the least square method. Above all, noise of signals was effectivelyreduced by using spectrum estimation technology.(4) Real layer structure model is analyzed by using radar signal processing technologyand1D-layer stripping method. The results indicated that errors are lower than8%and can satisfy the precision requirement of the project. The relation of water content and dielectricconstant is discussed in standard sands utilizing GPR method. The new fitting Toppedformula and Alharath formula were obtained by analyzing the experimental data, whichfurther validated that using GPR method can estimate the water content of layer media.更多还原