探地雷达在公路隧道中的应用研究

发布时间：2018-05-05 01:12

本文选题：探地雷达 + 数值模拟　；参考：《广西大学》2014年硕士论文

【摘要】：探地雷达是在隧道衬砌健康检测、隧道超前预报等工程中广泛使用的物探工具。它以无损、高效、分辨率高的特点深受工程人员的亲睐。然而,在我国探地雷达的应用还处于初级阶段,在实际工程中很多问题亟待解决,例如,探测参数的设置尚无统一标准以及探测图像的解译缺少依据等。这些问题的存在影响了雷达探测的准确性。本文通过数值模拟和物理模拟方法,结合在岑溪大隧道、垌尾隧道以及岭脚隧道中的衬砌检测经验,对探地雷达在公路隧道衬砌检测和超前预报中的应用进行研究,本文研究的主要成果如下： 1.采用二维的时域有限差分法,对探地雷达进行正演模拟。从麦克斯韦电磁方程出发,推导出TM波在二维空间的有限差分方程,借助完全匹配边界条件解决在有限空间内模拟电磁波在无限空间传播的问题,使用Matlab软件编写模拟程序,对隧道衬砌检测和超前预报中典型的地电模型进行正演模拟,取得了正演图像,为实际应用中的反演提供依据。 2.分别进行隧道衬砌和超前预报不良地质体模型试验。通过隧道衬砌模型试验,研究了钢筋网对于雷达信号的屏蔽作用,混凝土龄期对雷达波速的影响,二衬分界面位置的判断方法,以及衬砌中空洞、不密实、钢拱架、钢筋网的辨识方法。通过对隧道超前预报不良地质体(破碎带、富水区、中空溶洞、含水溶洞、节理)的模拟,获取了其典型图像,并和数值模拟中得到的图像进行对比,总结了图像特征。 3.研究了计算岩溶洞穴尺寸方法,并通过试验,分别验证了波速替换法、渐近线法在计算洞穴尺寸中可靠性和准确性。 4.根据岑溪大隧道、垌尾隧道以及岭脚隧道的衬砌检测实例,对探地雷达在衬砌检测中参数设置、数据分析的方法进行研究。结合实际开挖情况,得到了各种衬砌缺陷所对应的典型图形,并对比数值模拟和物理模拟结果,总结图像特征,为衬砌检测中的图像解译提供依据。
[Abstract]:Ground penetrating radar (GPR) is a widely used geophysical tool in tunnel lining health detection and tunnel advance prediction. It has the characteristics of nondestructive, high efficiency and high resolution. However, the application of GPR in China is still in its infancy, and many problems need to be solved in practical engineering. For example, there is no uniform standard for the setting of detection parameters and there is no basis for interpretation of detection images. These problems affect the accuracy of radar detection. In this paper, through numerical simulation and physical simulation, combined with the lining detection experience in Cenxi large tunnel, Tongwei tunnel and Lingjiao tunnel, the application of ground penetrating radar in highway tunnel lining detection and advance prediction is studied. The main results of this paper are as follows: 1. The forward modeling of ground penetrating radar is carried out by using two dimensional finite difference time domain method. Based on Maxwell's electromagnetic equation, the finite difference equation of TM wave in two-dimensional space is derived. The problem of simulating electromagnetic wave propagation in finite space is solved by means of perfectly matched boundary condition. The simulation program is written with Matlab software. The forward modeling of typical geoelectric model in tunnel lining detection and prediction is carried out, and the forward image is obtained, which provides the basis for inversion in practical application. 2. Model tests of tunnel lining and advanced prediction of poor geological bodies were carried out respectively. Through tunnel lining model test, the shielding effect of steel mesh on radar signal, the influence of concrete age on radar wave velocity, the method of judging the location of interface between two linings and the hollow, undense and steel arch frame of lining are studied. Identification method of reinforcement mesh. The typical images of poor geological bodies (broken zone, water-rich area, hollow cavity, water-containing cave, joint) are obtained by simulation of tunnel advanced prediction, and compared with those obtained in numerical simulation, the image features are summarized. 3. The method of calculating the size of karst cave is studied and the reliability and accuracy of wave velocity replacement method and asymptote method in calculating cave size are verified by experiments. 4. Based on the lining detection examples of Cenxi large tunnel, Tongwei tunnel and Lingjiao tunnel, the parameter setting and data analysis method of ground penetrating radar in lining detection are studied. Combined with the actual excavation situation, the typical figures corresponding to various lining defects are obtained, and the results of numerical simulation and physical simulation are compared, and the image features are summarized, which provides the basis for image interpretation in lining detection.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U459.2;U456.33

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