介电参数数值实验在探地雷达试验检测中的应用

相对介电常数标定是探地雷达试验检测的重要内容,直接影响探地雷达的试验检测精度,常规的方法是采用取芯进行校正,从反射时间和芯样厚度来获取波速和近似的相对介电常数,常常忽略了介电参数中电导率对雷达波速的影响。为减少单一的取芯校正方法带来的误差,采用时域差分法,对不同电导率的钢筋混凝土介质的双介电参数进行数值实验,分别从数值模拟剖面、单道波信号、电场分量波场快照3个方面,讨论了钢筋混凝土介质的相对介电常数、电导率和波速三者之间的关系,并分别采用三次插值和双调和样条插值方法获得了双介电参数对雷达波速校正的相关关系。结果表明:双介电参数与雷达波速的相关关系呈分段曲面分布,应综合考虑电导率和相对介电常数来进行雷达波波速校正。

Application of dielectric parameter numerical experiment toGPR test and detection

Relative permittivity calibration is an important part of ground penetrating radar (GPR) test and detection, which directly affects the test accuracy of GPR. Conventional core-drilling method uses reflection time and the thickness of core to get wave velocity and approximate permittivity, and often ignores the influence of the conductivity on the radar wave velocity. In order to reduce the errors caused by the single core-drilling method, we used the time domain finite difference method to carry out numerical experiments on the double dielectric parameters of reinforced concrete with different conductivities, investigated the relationship among the relative permittivity, the conductivity and the radar wave velocity of the reinforced concrete from the three aspects of the simulation sections, the single scan signal and the snapshots of E_z component respectively, and obtained the correlation between the double dielectric parameters and the radar wave velocity calibration with cubic interpolation and biharmonic interpolation. Results show the correlation between the double dielectric parameters and the radar wave velocity calibration is a section surface distribution and the conductivity and relative dielectric parameters should to be integrally taken into account in radar wave velocity calibration.