Mapping geotechnical properties using geographical information system: A case study of Siirt city

Siirt is one of the most important cities in the Southeastern Anatolian Region. The faults around the Southeast Anatolian and neighbouring has generated severe earthquakes in the study area. In this study, mapping of the geotechnical properties by Geographical Information System in Siirt Central District is aimed to be presented. The city center of Siirt is situated at 37o 55' 38'' North and 41o 56' 31'' East coordinates and is influenced by active faults connected to the Eastern Anatolian Fault Zone and Southeast Anatolian Thrust. The main goal was to provide ease of access to geotechnical data in the field of engineering, to support the workforce and to increase the efficiency. A total of 178 borehole points was obtained from the soil investigation reports of Siirt Environment and Urbanization Directorate. Geotechnical maps were created by transferring the field and laboratory test results which were obtained from the soil investigation reports to ArcGIS software by means of Geographic Information System. Calculations, mapping and analysis of SPT-N, bearing capacity, shear wave velocity, soil amplification, dominant vibration period and soil classifications according to NEHRP, EUROCODE8 and TBDY-2019 earthquake codes were made. Bearing capacity calculations were made in 4 different methods according to geophysical and geotechnical approaches. Both approaches have shown a great difference when have compared. Also, shear wave velocity values have been calculated and compared according to different scientist in the literature. Furthermore, many other maps and analysis were made, which will be available online in the Siirt Municipality. This analysis will save time and help the workforce in future studies.