الفهرس 
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Abstract
New El Alamein City, where the study area lies, is one of the iconic cities in the Egyptian Northwestern Coast of Egypt, isn’t only housing units but also summer resorts for tourist attractions. The present study conducted geophysical investigations to determine the presence of clay lenses, and the intrusion of seawater into subsurface layers, and to assess its geotechnical characteristics for construction purposes. Two distinct geophysical methods were employed; Shallow Seismic Refraction (SSR) and Electrical Resistivity Tomography (ERT) with soil tests conducted in the laboratory to play a crucial role in supporting and complementing the information obtained from geophysical tools in geotechnical and engineering investigations.
The core samples were collected from nine drilled boreholes distributed in the study area. Nine ERT profiles, directed northwest-southeast parallel to the shoreline of the Mediterranean Sea, were employed to investigate the intrusion of seawater into layers and the presence of clay lenses. SSR, known for its environmental friendliness, involved nine seismic profiles in the same sites of ERT profiles to measure primary and secondary wave velocities and to compute the elastic moduli including shear modulus, young modulus, and bulk modulus in addition to near-surface geotechnical properties such as Poisson’s ratio, stress ratio index, concentration index, material index, N value, density gradient, and bearing capacity of foundation materials. These data were instrumental in selecting optimal construction sites.
from ERT data, seawater intrusion into layers was observed at various depths. Three geoelectrical layers were observed without horizontal variations indicating the absence of clay lenses. SSR data show a good match with the data extracted from core samples in terms of the existing layer numbers and thickness. SSR data indicate that there are three layers according to their velocities; two of them are observed along profiles 1 and 9, while three layers are observed along profile 5 in the middle of the study area.
The integration of these findings classified the area into two zones; Zone A is suitable for low-rise buildings with a second layer used as a foundation layer, and Zone B is heavily affected by seawater intrusion and unsuitable for construction or need to improve the strength of concrete exposed to seawater in this zone to be suitable also for buildings with a low height.