Geotechnical Evaluation of Foundation Zone Soil and its Response to the Groundwater Fluctuation at the North Refinery Company Expansion Sites, Northern Salah Al-Din Governorate.

The study aims to conduct a geotechnical evaluation of the soil of four suggested sites for expansion in the North Refineries Company, northern Salah Al-Din Governorate. The study area is located on the southwestern limb of Makhul anticline within the Quaternary sediments to determine their suitability for the establishment of some engineering facilities, and to assess the quality of the groundwater through chemical analyses and developing a model that simulates the effect of groundwater fluctuation when establishment as new projects.Physical and engineering tests are carried out as well as chemical analyses. The moisture content ratios range between (6.39 -13.40%), specific gravity range between )2.67- 2.74). From the results of the grain size analysis of soil, the percentages of clay and silt are found to be the highest and based on Atterberg limits and according to the plasticity scheme, it is found that the types of soil are CL and ML classification the soil is into (medium plasticity, slightly plastic). The results of the engineering properties from the direct shear test show that the internal friction angle ranges between (21-33), cohesion strength between (56-81 kPa), and the results of the consolidation test show that the soil is over consolidation O.C.R. The chemical analyses indicate that the gypsum content is low to medium, and a neutral alkaline soil with an organic content range from low to high, and contains a high percentage of sulfates, fluorides and bicarbonates. The percentage of dissolved salts exceeds (0.5%) and is considered high. The electrical conductivity (EC) will also be high. The groundwater depths are measured by a groundwater depth detector for wells distributed in the study area and samples are taken from several water wells located near the facilities. The results of chemical analyses show that the classification of water according to (pH) is from moderate to weak alkalinity. When comparing the concentration of total dissolved salts of groundwater in the study area, it is found that the water of the study area is brackish water; and according to the classification of water depending on the values of total hardness, it is found that the water of the study area is of high hardness.