Investigation of geotechnical characteristics of the 5th and 6th rainwater drainage regions in Aksaray province

In this study, the soil properties of the 5th and 6th rainwater catchment areas of Aksaray province were investigated by using the geotechnical and hydrogeological data obtained from 102 exploration drillings. The geological units observed within the boundaries of the study area are alluvium and alluvial cones. Up to a depth of 10 meters, soil shows a generally heterogeneous profile consisting of gravelous sand and gravel, brown-gray color, clay, sandy-silty clay, clay-silty fine sand, clayey-sandy silt. The ratio of fine-grained soil is 88 % and coarse-grained soil is 12%. Fine-grained soils in region generally show low plasticity silty clay (CL) type soil characteristics. 94% of the fine-grained soils are inactive - medium compressibility clay feature. 80% of fine grained soils have medium swelling potential. The mean ultimate bearing capacity of soils for raft foundation calculated according to the Terzaghi (1943) and Turkey Building Earthquake Regulation (TBDY) methods are 1.69 kg/cm2 and 3.81 kg/cm2, respectively. Bearing capacity of soils for continuous foundations are 1.36 kg/cm2 (acc. to Terzaghi) and 3.23 kg/cm2 (acc. to TBDY). Average values of some physical properties of soils; are natural unit weight 1.9 gr/cm3, natural water content 22%, liquid limit 43.4 %, plastic limit 20.9 % and plasticity index 22.4 %. The liquefaction potential index averages of studied area calculated according to 6 Ms and 7 Ms earthquake scenario are 0.29 and 1.37. According to the results of water chemistry analysis performed on water samples taken from 26 research wells, the mean values of the carbon dioxide, ammonium, magnesium and sulphate concentrations in groundwaters have been measured 33.2, 0.64, 80.4 and 372.9 mg/L, respectively. In terms of CO2 concentrations, 27% of groundwaters have a strong corrosive efficiency ratio for concrete and reinforcements in the foundations of buildings. This ratio has been calculated as 19% for the SO4 concentration.