A mapping study of geotechnical soil properties of Tunceli province centre using GIS

The utilization of Geographic Information System (GIS) technology is highly significant in engineering projects as it improves efficiency, saves time, and reduces costs. GIS plays a crucial role in various tasks such as map-ping land data, storing and analyzing data, and facilitating information sharing. By integrating maps, data, and analytical capabilities, engineers benefit from enhanced visualization, accessibility, and shareability of project outcomes, ultimately leading to improved project quality. Understanding soil properties is fundamental in the planning, construction, and long-term safety of buildings and infrastructure. It involves determining factors like soil bearing capacity, susceptibility to liquefaction, shear wave velocity, and making informed decisions about soil selection based on these properties. In this study, a comprehensive analysis of geotechnical soil data, laboratory test results, and geological information from 96 borehole sites was conducted. The focus was on examining SPT-N values at different depths of the boreholes (3.0, 4.5, 7.5, 9.0, and 15 m) commissioned by the Tunceli Municipality Urban and City Planning Provincial Director for urban planning purposes. Geotechnical maps were created using ArcGIS software by calculations derived from borehole data, laboratory soil tests, and geophysical testing results. Various assessments, mapping activities, and analyses were carried out, including evaluations of SPT-N values, bearing capacity, shear wave velocity, soil amplification, dominant vibration period, and soil classifications based on earthquake codes such as NEHRP, EUROCODE8, and TBDY-2019. The study findings revealed a prevalence of SPT-N values exceeding 35 within the study area. Soil bearing capacity assessments were conducted using the Terzaghi & Peck and Meyerhof calculation methods, yielding a range of 300-600 kN/m2. Notably, lower bearing capacity values were observed at a depth of 1.5 meters in certain areas such as the central, eastern, Cumhuriyet, Moğultay, and Atatürk neighborhoods. Furthermore, a liquefaction risk was identified in the central part of the study area, encompassing Atatürk, Cumhuriyet, and Moğultay neighbor-hoods, while the remaining areas were classified as having "non-liquefiable" soils. Shear wave velocity calcula-tions conducted at a depth of 30 meters yielded values ranging from 286 m/s to 1271 m/s. It is important to acknowledge that any inaccuracies in the geotechnical borehole data could impact the results of the study, as the analysis assumes that the data collected is both valid and representative. Keywords: Tunceli, mapping, GIS, SPT, geotechnics.