介电常数对探地雷达检测隧道壁注浆效果研究

利用探地雷达方法探测软土盾构隧道盾尾壁后注浆分布效果时，电磁波波速的确定．是保证探测精度以及图形识别的关键技术之一。文章首次利用网络分析仪对影响探地雷达探测精度的壁后注浆材料的介电常数在不同频率下进行了测定，对试验结果进行了正演分析，并与介电常数恒定时的波形进行比较。结果表明针对不同的探地雷达探测频率，采用相应不同的介质介电常数来进行探地雷达探测图像的识别是十分必要的。

Research of the Effect of Dielectric Permittivity on the GPR Detection for the Grouting Material Behind Shield Tunnel Segment

When GPR is used to detect the effect of grouting behind the tunnel segment at the shield tunnel tail, determination of the velocity of electromagnetic wave is a key technique for assuring the detecting precision and figures identification. In this paper, a network analytic instrument is firstly introduced to detect the dielectric permittivity of groudng material which affects the measurement result of CPR. Some direct deduction analyses on obtained graph have been done by a lot of tests under different frequencies, and the data are compared with the results of the same dielectric permittivity of grouting material and soils. This study shows that it is necessary to adopt different dielectric permittivities according to the different frequencies.