Geological and Geotechnical Investigations to Detected Foundation Parameters for Some New Urban Areas, Sohag Governorate, Egypt

Abstract

The study area is located in Upper Egypt as a part of the Sohag Governorate. In this study, the engineering geological properties for soil deposits of three new urban areas in the southwestern part of the Sohag Governorate are discussed and evaluated based on a field survey of soil boring, geotechnical experiment and petrographical examination. The studied area is covered by Quaternary and Pliocene deposits and composed mainly of gravely sand, silty sand, silty clay, clayey silt and rocks. Twenty-three sections, forty-two soil samples and three thin sections were studied. The depth of these samples ranges between land surface and up to 10 meters below underground. The geotechnical tests for the collected soil samples were performed to determine their physical, and mechanical characteristics (grain size distribution, specific gravity, and water content, bearing capacity, free swell and Atterberg limits). From the results, the grain size analysis proved that, the arenaceous sediments (average MZ=1.75Φ) falling in the medium sand grade. Mineralogical studies of X-ray diffraction examination of the collected samples reveal, the argillaceous deposits are composed mainly of montmorillonite, kaolinite and illite. The free swell test is ranging from 20 to 130% indicate that, some of the studied clay samples are high expansive. Thus, these soils are not suitable to direct foundation due to high swelling properties, which have a dangerous effect on the buildings. The liquid limit results range from 13 to 72%, the values of the plastic limit range from 9.8 to 32 % while the values of the shrinkage limit range from 9.3% to 25%. The values of the liquidity index range from 0.06 to -1.60. The liquidity index of studied samples is semi plastic or solid. The values of consistency index of the studied samples range from 0.65 (very stiff) to 2.59 (extremely stiff). The effective friction angle (Ф) ranges from 33.5° to 34.8°. The ultimate bearing capacity for different friction angles of the studied samples are ranging from 1312.2kN/m2 to 1533kN/m2. So, this type of soil is suitable for direct foundation.