Geotechnical Characterization and Shear Strength Analysis of Gypsum-rich Soil in the University of Tikrit, Center of Iraq

The results obtained from the geotechnical investigations are essential and useful in designing engineering projects. Additionally, they can help in identifying future problems surrounding the project and provide appropriate solutions to these problems. The physical properties are utilized in the classification of soils for engineering purposes. This study identifies some geotechnical properties of the designed models. Geotechnical tests are conducted to evaluate the engineering properties of the soil samples at the University of Tikrit to identify their weak zones, down to a depth of 3 meters. The values of specific gravity range between (2.41-2.46) due to the high gypsum content in the soil. Models with low moisture content are observed with moisture content values ranging between (2.78 and 8.11%). Atterberg limit tests are conducted, and the examination failed in models containing small proportions of clay, except for three models, where the Atterberg limits are found (St.4, St.6, St.7). The liquidity index values are (22.14, 22.95, 23.37) respectively, while the plastic limit values are (19.57, 20.14, 21.35) for the same models. The results show that the soil is of type (SM). Proctor compaction tests are performed, where the maximum dry density values range between (1.691 and 1.778 g/cm), while the optimum moisture content values range between (12.7 and 15.2%). As for shear resistance parameters, the cohesion values (C) range between (40 and 49 kPa), and the internal friction angle values () range from (30 to 35).