ASSESSMENT OF SWELLING POTENTIALITY OF CLAY AT EL-FAYOUM NEW CITY: GEOTECHNICAL AND SHALLOW SEISMIC REFRACTION PROSPECTING

Abstract

El-Fayoum New City represents one of the new urban settlements that are recently founded on some parts over Egypt. Expansive soils in El-Fayoum New City are considered among the difficult foundation materials and expand upon wetting. They are considered problematic soils for architectural and civil engineers, when used as foundation materials to support various types of civil engineering structures. This type of soils may cause minor to major structural damages to pavements and buildings. Expansive soils are clay soils containing considerable amount of montmorillonite clay mineral, which has a potential for swelling or shrinking, due to changes in its moisture content. Many laboratory tests were carried out to determine the swelling clay behavior. Physical properties such as, bulk density water content and as well as geotechnical properties, like Atterberg limits, consistency index and swelling potentiality have been achieved. Mineralogical composition of clay was also defined using X-ray diffraction. Results of the laboratory tests document the presence of clay layers that are composed essentially of montmorillonite, which cause high swelling potentiality of soil in the area under study. Several thin clay layers intercalated with sand and gypsum pockets are found in the study area. The thickness of these clay layers is sometimes below the seismic resolution and in other times above it and can be resolved. Moreover, the vertical seismic resolution has been determined to detect the thickness of thin clay layers that may cause soil swelling which in turn, severely damage the foundation and crack the building structures. Finally, essential solutions for this problem were recommended.