Hakan Akcin

Monitoring deformations on engineering structures in Kozlu Hard Coal Basin

Underground coal mining activities in Kozlu Hard Coal Basin have reached a level affecting ground layers inside the mining seams and the surface just above the mining operations, causing movements in vicinity of the basin. The movements emerge as collapsing in vertical direction and as sliding, curling and bending in horizontal direction and are termed mining subsidence since they exhibit themselves in ground layers and on earth surfaces in mining environments. These mining-induced movements cause damages and destructions on structures inside and on the surface of mining grounds, and the dimensions of these damages depend upon quality of structures and magnitude of movements. In order to contribute toward a solution to these problems and to mitigate the effects arising during and after mining activities, one should identify and investigate damage prone movements and determine the movement–time relationship. Therefore, it is immensely important to observe, investigate, and measure these movements in regions where mining activities take place. This study focuses on the surface movement-related deformations on the engineering structures in the basin such as Kozlu Seaport and some part of the Zonguldak-Kozlu Road. For this reason, subsidence monitoring points were established on the engineering structures in the basin in a geodetic network concept, and three periods of precise leveling and static GPS observations were conducted. Analyzing these two types of geodetic observations, active and residual subsidence effects were determined for both Kozlu Seaport and the Road nearby.

A comparison of two well known models for 7-parameter transformation

The transformation between two geocentric coordinate systems is carried out by the seven-parameter similarity transformation comprising three translations, three rotations and one scale difference. A number of approaches are available to realise this. Nevertheless, the Bursa-Wolf and Molodensky-Badekas models are generally favored for their simplicity. Except for their translations and their rms values both models yield similar results. Choosing a model producing more realistic translations is, of course, of paramount interest to surveyors. In this study, investigation of the causes of differences between translations of both models and which of these models produces more precise results is taken into consideration. The outcome of this investigation showed that the mathematical model of the Bursa-Wolf as opposed to the Molodensky-Badekas causes high correlations between transformation parameters, so Molodensky-Badekas model determines the translations better than the former.

Monitoring of mining induced land subsidence using L- and C-band SAR interferometry

In this study, we applied InSAR technique to Zonguldak Hardcoal Basin in Republic of Turkey using JERS-1/SAR, RADARSAT and PALSAR data in order to monitor mining induced surface displacement.

Automatic processing of interferometric SAR and accuracy of surface deformation measurement

Interferometric Synthetic Aperture Radar (InSAR), one of typical application techniques of SAR data, is used to generate Digital Elevation Model (DEM) while it is also used to measure spatial surface deformation. The former and the later techniques are usually differentiated as InSAR and Differential InSAR respectively. In this paper, we focus the later technique as InSAR. We measured ground deformation using automatic InSAR processing and verified accuracy of obtained results. The study area is Zonguldak coalfield, located along the Black Sea coast approximately 240 kilometer away from Istanbul to the east, Republic of Turkey. In this region, underground coal mining has been undergoing since 1848 and 3 million ton per year of hard coal has been produced. Recently, this coal mining is found to be causing subsidence around this area. Since the whole damage has not been grasped, we tried to measure the amount of surface deformation using InSAR. As a result, some phase anomalies were detected just above mining drifts, and the largest deformation amounts among those was 204 millimeter per 4.5 months in slant range direction. In addition, InSAR results are corresponded with GPS measurement results within 9 millimeter variations.