Research of the sea-filled airport OGU in the Black Sea, Turkey, using ground penetrating radar method

Abstract

The primary aim of this study was to research filled layers, including the runway, aprons and taxiway of the newly constructed sea-filled airport OGU, next to the beaches of Ordu and Giresun cities in the Black Sea, Turkey, using the ground penetrating radar (GPR) method. The second aim was to compare the determined bottom boundary line of the filled layer on the processed radargrams with the bathymetric line measured after clearing the unconsolidated sediments of the Black Sea before construction along the measurement profiles. Finally, a special data processing method, including deconvolution, migration and F-K filtering, was to be applied on the basic processed radargrams to develop imaging of the sea-filled layer.This study was important for imaging the special characterized thin layers of the airport runway and aprons that were constructed with a filled layer, on the sea, which is composed of different sized andesite and basalt rock pieces, along with aglomera and seawater. This study was a test of the GPR method to image such a layer. There were four drilling points to control the deviation of the bathymetry. Therefore, six different appropriate GPR profile data measurements were taken, crossing these points with the runway and aprons using 100MHz shielded GPR antennas. According to the traditional processed radargrams, effects of different sized rock blocks and changing amounts of seawater were avoided to line the bottom of the filled layer. In addition, there were clutter effects and multiples on the radargrams. A deconvolution and F-K filter and migration were applied to remove clutter, multiple and scattering effects that were particularly seen at high frequencies. Finally, the depth line of the filled layer could almost be revealed. To realize the second aim, a topographic correction was applied to the processed profile data. Then, bathymetric lines were merged onto the radargrams. Finally, differences between bathymetric lines and the bottom boundary lines of the filled layer of the runway and aprons were compared. The results showed that there have been small deviations for the bathymetric line under the aprons that are probably the reason for the small amount of residual unconsolidated sediments in the small trenches at the sea bottom. No deviation has been observed under the runway of the airport. The results also showed that the GPR method, along with the process of deconvolution and F-K filtering to remove clutter and multiple effects, could be used successfully to determine the boundary line of the sea-filled layer in the Black Sea.