Combined Migrations and Time-Depth Conversions in GPR Prospecting: Application to Reinforced Concrete

In this paper, we propose the combination of different migration results achieved on the same data in order to account for different values of the propagation velocities of the electromagnetic waves within the considered Ground Penetrating Radar (GPR) profile. These different values can be the result of a variable lithological composition or (more probably for short Bscans) the results of different moisture levels, or both. Here, we separately consider the two cases of horizontal or vertical variability of the propagation velocity with a transition zone between two zones with constant propagation velocity. Moreover, we also propose a time-depth conversion accounting for these different values of the propagation velocity along the considered GPR Bscan. The method is applied to real data gathered in the field with regard to a concrete coverage containing liner layers.