The tunnel lining detection numerical simulation based on GPRMax and its application
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摘要: 利用基于时间域有限差分法( FDTD)的GPRMax,针对常用的400、900、1500 MHz三种不同中心频率的天线,数值模拟了隧道衬砌不同钢筋网密度、不同钢筋直径及其下方的钢拱架、空气界面等目标体的探地雷达反射及干扰信号图像特征;在混凝土试件上开展实验研究,并运用克希霍夫积分偏移处理了数值模拟和实验数据,压制了钢筋的绕射波和多次波,提高了钢筋网下方弱反射信号的成像效果;通过对比分析数值模拟、实验测量和工程实测结果,为探地雷达在隧道衬砌检测中取得更好的探测效果提供了借鉴。Abstract: Using GPRMax basd on the theory of finite difference time domain ( FDTD) , and taking into account three different frequen?cy antennae of 400 MHz, 900 MHz, and 1500 MHz, the author simulated the image characteristics of the ground penetrating radar re?flection and interference signal obtained from the objects inside tunnel lining, including different steel mesh densities, different rebar diameters, steel arches and air layers. An experiment of ground penetrating radar survey was carried out on concrete specimen, the Kirchhoff migration was used to process the numerical simulations and experimental data, so as to suppress the diffracted wave and mul?tiple wave coming from rebar mesh and improve range resolution of weak reflection signal under steel mesh. Based on the comparative a?nalysis of the numerical simulation data and the experimental data on concrete specimen and tunnel lining detection results, the authors reached some conclusions which can be used as a reference for obtaining better detection results of ground penetrating radar survey in tunnel lining.
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