Abstract:

The characteristics of the depth and defects of the tunnel lining layers need to be extracted accurately from the data collected in the tunnel lining quality detection by means of Ground Penetrating Radar (GPR) In the paper, aircoupled GPR is used for the lining quality detection, and the identification of the characteristics of the lining layer is studied based on Matlab and GprMax2D platforms Conclusions drawn are as follows: 1) 2D forward simulation of several types of lining and the characteristics of electromagnetic wave reflection within multilayered mediums are studied under actual working conditions The analysis shows that the reflection echo of GPR does not start from zero, and the reflection time of the electromagnetic wave on the boundary layer between two mediums depends on the thickness of the electromagnetic wave propagation layer For two medium layers with big difference or with some air between the two medium layers, the reflection time is located at the maximum peak or the trough of the waveform, which is independent of the position of the impulse source emitted from GPR and the dielectric constant of the second medium layer 2) The GPR data and actual interference factors of the tunnel lining are analyzed on basis of the characteristics of the tunnel lining layers, and the big errors from the theoretical reflection time is modified The paper can provide guidance and reference for the identification of the tunnel lining layers and defect properties of similar projects in the future

Key words: tunnel lining layer, characteristics identification, aircoupled ground penetrating radar, forward simulation