Detecting physical and geometrical parameters of some common geotechnical targets through their effects on GPR responses

Abstract

Ground-penetrating radar (GPR) responses expected over a number of synthetic models resembling some commonly encountered geotechnical structures including single horizontal cylinder with different fluid contents, double horizontal cylinders, and 2D arbitrary polygonal bodies have been simulated using an improved finite difference time domain forward modeling algorithm. In the first part of this study, we investigate the effects of such synthetic model parameters on GPR responses. Based on the effects of the studied parameters on GPR responses, it is shown that there exist mathematical relationships between the characteristics of GPR responses (the typical hyperbolic shapes) and the respective geometrical and physical parameters of subsurface hidden targets. It is concluded that we can efficiently apply such mathematical relationships between model parameters and GPR responses to derive estimations of hidden subsurface parameters in real field data. In order to show the applicability of the approach outlined in this study, the geometrical parameters of a known hidden qanat in Shahin Shahr plain, Isfahan Province, Iran are estimated. Finally, it is shown that the GPR response of two hidden horizontal cylindrical objects is just an aggregate of each single object response which in turn can be processed with the same approach developed for single objects.