عنوان مقاله [English]
In current study, GPR (Ground-Penetrating Radar) method has been used to identify physical and geometrical parameters of buried cylindrical targets including tunnel shape structures. To achieve this goal, the well-established mathematical relationships between geometrical parameters of cylindrical target (radius, burial depth and horizontal location) with the associated GPR hyperbolic response characteristics are employed using the template matching method. In order to validate the applicability of template matching method in providing estimates of such parameters, the method was first tried on GPR responses of synthetic data with known geometrical parameters followed by applying on real data using two different similarity criteria including 2D spatial convolution and normalized cross-correlation in the wave number domain. The results of the study for several diverse tested synthetic models reveal that the proposed algorithm can estimate the known geometrical parameters of the cylinders with great accuracy (maximum error of 15 percent). The template matching algorithm was also used to extract geometrical parameters of a qanat buried in Shahin-shahr plain, Isfahan province. Depending on environmental conditions and subsurface host materials, the real GPR data normally contain a variety of noises, therefore a series of appropriate and objective preprocessing and processing stages were designed in order to apply on real GPR radargrams before deploying template matching algorithm. The applicability of the template matching algorithm on real data and validity of the estimated parameters were proved based on assessing the accuracy of estimated values geometrical parameters of the qanat through GPR response versus the measured parameters. The proposed algorithm is designed in such a way that all stages of the estimation of geometrical parameters of buried cylindrical targets are automatically carried out.