Monitoring of the stability problems on the Ankara-Konya high speed railway line (Turkey) with ground penetrating radar method

The aim of the study is to research the stability problems of the high speed railway line according to rock properties and their discontinuities such as fractures, faults and karstic cavities between the capital city Ankara and the largest city Konya in Turkey. A bi-static 100 MHz center band shielded antenna was used to take measurements of two dimensional (2D) profile data. Total 35 km was surveyed on different parts of the railway line by considering the results of the geologic research and petrograpical studies. During studies, we gathered the data on the backfilled way on the three parallel profiles spaced 1m apart or on the service way next to the railway line. There was a tunnel on the line. We also gathered two parallel profiles data on the tunnel and four profiles data next to the tunnel to evaluate the stability conditions according to the discontinuities. This paper presented also determining fractures, carstic cavities, faults with their depths on two dimensional (2D) radargram and on transparent 3D GPR data visualization by assigning an opacity function to the amplitude-colour range and view angle. The petrographical studies and GPR results indicated that the areas with Jurassic alloctonous limestones thrusted on the ophiolitic rocks had deep and large fractures and cavities. The resulted radargrams indicated the thrust fault locations under the rail line. This limestone were rootless and did not have big thickness. The radargrams were also revealed the stability conditions of the tunnel on the rail line. There was an important collapsed zone filled up before. However, some part of it was still had a problem. There were approximately horizontal fracture segments under some parts of the tunnel 8m in depth. This fracture were crossed the collapsed zone.