Evaluation of Some Geotechnical Properties of the Soil of a Proposed Site for the Construction of Residential Complexes, Northwest of Tikrit City

Some geotechnical properties of the soil at depths between (0.5-6 meters). of a proposed site for the construction of residential complexes, northwest of the city of Tikrit are evaluated for three stations represented by six models. The moisture content is (0.41% - 3.39%), the specific gravity values are (2.39% - 2.61%). The particle size analysis show that the soil of the region has particle sizes of the coarse type (gravel, sand) and fine type (silt, clay). The percentage of gravel is (0%-74.09%), sand (21.58%-67.88%), silt (3.59%-32.03%), clay (0.14%-23.84%). The plasticity test shows that most of the stations in the study area lack the presence of clay, with the exception of model (C) for station (3), which has a fluidity limit of (22), a plasticity limit of (19). The plasticity index values for the model reached (3), and the compression index values for models (C, A2) respectively are (0.95-0.45), and the swelling index ratio (Cr) for the two models ranges between (0.31 and 0.083) meaning that the soil has a low swelling ratio due to the lack of clay minerals that can swell in the soil. The maximum dry density values are (1.80 - 2.5 gm/cm3) and the ideal moisture content values are (6.1% - 12.1%). Chemical analyses show a high percentage of gypsum in the soil ranging between (1.06% and 46.25%). The percentage of soluble salts is (3.01%-50.07%). The percentage of organic materials (0.017%-0.062%). The pH is (7.82% - 8.11%), and the chlorides (0.21% - 1.82%). We conclude from this study that the studied soil is not suitable for engineering projects in its current condition