Use of geographical information system for the evaluation of some geotechnical properties in Batman, Türkiye

Geographic Information Systems (GIS) is a collection of data that offers features such as analyzing geographical data, querying, visualization, statistical analysis, and spatial analysis. Within the scope of construction areas and urban planning, GIS is used in digital mapping studies, allowing for more effective examination, interpretation, conclusion, and planning of data. This study aims to minimize risks emerging from geotechnical problems, specifically seismic site effects and soft soil properties. Soil survey reports, field and laboratory test results obtained from the archives of Batman Municipality's Directorate of Zoning and Urbanization were used during the study. Geological, geophysical, and geotechnical data obtained from 253 borehole logs within a region of approximately 54 km² of the Central District of Batman Province were analyzed using GIS Inverse Distance Weighting (IDW) method. Engineering properties of soils were examined according to various depths (1.5, 3.0, 4.5, 7.5, 9.0 and 15.0) in the study area. The study included a standard penetration test (SPT), bearing capacity, groundwater level, consistency limits, shear wave velocity (VS), site dominant vibration period (T0), and soil classification analyses according NEHRP, EUROCODE-8 and TDBY2018 earthquake regulations. The blow number of the standard penetration test (SPT-N) range from 4 to 50. A total of 1398 soil samples are classified into nine different groups (CH, CL, GC, GM, GW, GW-GM, SC, SM and SW-SM) over a large area. The soil classification clearly indicates that clayey soil samples make up 89% of the study area, demonstrating their dominance. The analysis of shear wave velocity data at a depth of 30 meters revealed that the soil classes in the study area can be categorized as C and B according to the NEHRP and TBDY2018 classification or B and A according to EUROCODE-8. These soil classes are important for evaluating the seismic characteristics of the soil in the study area. Furthermore, the soil in the northern region of Batman is typically loosely packed, while other areas have medium to dense soil. Also, the proximity to the Batman River results in increased groundwater levels and low bearing capacity. In addition, water level beneath the ground ranges from 3.0 to 15 meters, but the highest percentage of water content is found at a depth of 1.5 meters, with a percentage reaching up to 41%. Finally, certain areas in Batman have alluvial soils and a high groundwater level, which increases the risk of liquefaction during earthquakes and for further studies it is crucial to identify and map these areas in the region.