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This study aims to evaluate the suitability of subsurface layers for infrastructure development using geophysical and geotechnical studies. Six seismic refraction and six 2D geoelectic profiles were conducted in the study area to analyze the geotechnical characteristics of the subsoil in order to assess its suitability for construction projects. According to the geophysical investigation, there are two main geoelectric strata, each with a different lithology and thickness. The first layer has high resistivity values of more than 200 (Ωm) and its thickness is between 3.5 and 6.3 m. The second layer's resistivity ranges from 0.3 to 200 (Ωm). The findings indicate that the near-surface area of the study site is composed of two layers in addition to the surface layer, which consists of semi-consolidated wadi fill deposits of gravel, sand, and silt with rock fragments. The first layer comprises fractured limestone with clay intercalation, followed by a second layer of marly limestone, which transitions into marl and clay. Both compressional (P) and shear (S) waves were detected and analyzed. The shallow seismic refraction technique indicates that the velocity waves (Vp) in the first and second layers range from 133 to 770 and 790 to 3100 m/s respectively. Various engineering parameters for the second layer were determined, including elastic moduli (bulk modulus, Poisson's ratio, rigidity modulus, and Young's modulus), competence scales (stress ratio, concentration index, material index and density gradient), and bearing capacity (ultimate and allowable). The average Poisson ratio for the first and second layers is 0.235. The ultimate bearing capacity (Qu) of the first layer ranges from 379.1 to 1031.2 gm/cm2 and between 1040.8 and 1548.5 gm/cm2 of the second layer. Allowable bearing capacity (Qall) for the first layer is between 126.4 and 343.7 gm/cm2, and for the second layer, it is between 346.9 and 516.2 gm/cm2. According to the geotechnical investigation's findings, the range of liquid limit (LL) values is between 41.20 and 86.30%, the range of plastic limit (PL) values is between 18 and 35.25%, the range of plasticity index (PI) values is between 14.17 and 51.45%, and the range of free swelling values is between 60 and 170%. However, the study identified high-risk areas in the study area. These zones are located in the first and second layers represented by strongly swelling clay layers and strongly fractured limestone, which will have a major impact on the road and buildings. Therefore, this study recommends addressing these problems before any development to protect these areas from subsidence and collapse. [ABSTRACT FROM AUTHOR]

Abstract El-Alamein new city is regarded as one of the iconic cities of the Egyptian North Western Coast to be not only residential units but also summer resorts for tourist attractions. This study examines the efficiency of integrating geophysical methods for determining if clay lenses exist or seawater has intruded into shallow strata and for calculating the geotechnical parameters of near-surface layers for construction purposes. Nine electrical resistivity tomography (ERT) and shallow seismic refraction (SSR) profiles are conducted in this study. From ERT data, we observed the intrusion of seawater in layers at different depths. From SSR data, two layers are observed along profiles, while three layers are observed along the other profiles according to their velocities. Near-surface geotechnical parameters, that were calculated from SSR data, are integrated to evaluate our study area. Accordingly, it was considered a low-competent area and suitable for buildings with low heights, and the only difference is the intrusion of seawater, therefore, it is subdivided into 2 zones. In zone (A), the second layer is used as a foundation layer. Zone (B) is pretentious by the intrusion of seawater, and it is not suggested to construct any buildings or to improve the strength of concrete exposed to seawater in this zone to be suitable also for buildings with a low height.

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The main target of the present study is to investigate the foundation layers and the subsurface structures in an Egyptian solar plant site using geophysical techniques including the seismic refraction and Multichannel Analysis of Surface Waves (MASW). The studied solar park is situated at about 40 km to the north of Aswan city on the Aswan-Cairo highway road and is classified as the largest solar plant in Africa and worldwide. Due to its location in the vicinity of the most prone earthquake area in Egypt (Aswan seismic zone); it is imperative to mitigate the earthquake hazard in this region. The geophysical results show that the subsurface foundation in this site is primarily composed of two layers. The upper one is loose and incompetent soil sediments that extend down to about 10 m depth with P-wave velocity ranging from 400 to 1000 m/s and shear-wave velocity ranging from 260 to 550 m/s. The deeper section is considered the main foundation layer with velocities ranging between 650 and 1900 m/s and from 350 to 950 m/s for P-wave and shear-wave, respectively. The average shear-wave velocities calculated for the topmost 30 m (Vs30) vary almost between 319 and 834 m/s; thereby the studied site is primarily ranked into classes C&D (180-360 m/s & 360-760 m/s, respectively) according to the National Earthquake Hazards Reduction Program (NEHRP) soil classification. Additionally, the southwestern and southeastern zones of the site area are characterized by maximum velocity values, relative high values of rock densities, rigidity or shear modulus "μ", Standard Penetration Test (N-Value), ultimate bearing capacity and allowable bearing capacity, while the low values are observed through the northern and middle sectors across the area. This study an integral part of many works being carried out delineating the subsurface foundation structures around the solar plant and allows the most appropriate sites for constructing the renewable energy plants to be sited away from the highly hazards prone areas. [ABSTRACT FROM AUTHOR]

Geotechnical hazards are the main factors that control decisions about construction in structurally complex zones. In the Mokattam area, Cairo, Egypt, different techniques, such as geotechnical techniques, remote sensing, and geophysical tools, are used and integrated to study the subsurface lithology, caves and structures to evaluate the possible geotechnical problems in these zones for expected future development in this area. Remote sensing applications indicate that the main trends of surface lineaments are E-W to NW–SE, whereas the minor trends are N-S to NE-SW. Ten vertical electrical sounding stations (VESs) were acquired and interpreted to delineate the subsurface stratigraphy. The interpretation results of these data show that the subsurface stratigraphy consists of 6 geoelectric units arranged from the surface to the bottom: fractured limestone, clay, marly limestone, dolomitic limestone, marl and marly limestone, and limestone. Nine electrical resistivity tomography (ERT) profiles, twelve shallow seismic refraction (SSR) profiles, and ten ground-penetrating radar (GPR) profiles were acquired to study the shallow subsurface stratigraphy. The integration results of ERT and SSR measurements indicate that the shallow subsurface stratigraphy is composed of different rock units. The first layer is fractured limestone, which represents the surface layer of the upper plateau and contains caves in some areas. Then, layers of clay and marl, which are important geotechnical hazard sources, are present. Finally, a layer of limestone appears in the bottoms of some sections, and this limestone layer also contains caves. The GPR profiles have the highest resolution and can discriminate the top horizon into three to four detailed stratigraphic units, each of which has different amplitude values and caves and fractures in some profiles. [ABSTRACT FROM AUTHOR]

The main objective of this paper aims to estimate the geotechnical parameters necessary for engineering constructions. For this purpose, thirty flat seismic refraction profiles were carried out in the study area northeast of New Minia City to describe the geotechnical properties of the subsoil for construction purposes. Both compressional (P) and shear (S) waves were detected and interpreted. The results show that the near surface section of the study area consists of two layers, the first layer of soil (sand from recent deposits), traversed by the second layer (sand and fragments of limestone) and changed laterally into fossiliferous limestone layer. Additionally, a number of engineering parameters for the second layer, such as elastic moduli (Poisson's ratio, bulk's modulus, rigidity modulus and Young's modulus), competence scales (material index, concentration index, stress ratio, and density gradient) and bearing capacity (ultimate and allowable) are determined. It was found that, the P-wave seismic velocities range from 2800 to 4500 m/s and the S-wave seismic velocities range from 1600 to 2750 m/s. Also, concluded that the values of Concentration Index, Material Index, Density Gradient, and Stress Ratio are ranging from 4.8 to 11.1, −0.053 to 0.603, −0.819 to −0.59, and 0.11 to 0.357, respectively. High difference between these two values reflects lithological, structural and textural variations occurred in rocks existed in the investigated area. The seismic velocity values and engineering parameters indicate that the bedrock at northwest and southeast of the study area have low competent rock quality, while the rest of the area have high competent rock quality. So, the suggested area for construction activities was about 9,489,876 m2 from total area 11,770,966 m2. [ABSTRACT FROM AUTHOR]

Nine vertical electrical soundings of Schlumberger configuration were measured with AB/2 = 1–500 m. Manual and computerized interpretation were done to detect the subsurface stratigraphy of the study area. The results show that the subsurface section consists of alternated units of limestone, clay, marly limestone and dolomitic limestone and the thickness of clay unit ranged from 10 to 40 m. Nine dipole–dipole sections have also been constructed to give a clearer picture of the subsurface at the study area. The length of each dipole–dipole section is 235 m, with a electrode spacing ranging between 5 and 25 m. The Res2Dinv software was used for processing and interpretation of field data. The dipole–dipole sections at the upper plateau display high resistivity values at most parts of the plateau. Twelve shallow seismic refraction profiles are measured at selected locations for the dipole sections to define the interface between the fractured limestone and the upper surface of the clay layer. Each profile consists of 24 geophones with a geophone spacing of 2–3 m. Interpretation of seismic data indicates that the surface layer of the upper plateau consists of fractured limestone with a velocity range of 1.16–1.56 km/s and another layer of compacted clay with a velocity range of 1.38–1.88 km/s. Furthermore, the surface layer of the middle plateau consists of marl and marly limestone with a velocity about 2.1 km/s and its underlying layer consists of massive limestone with a velocity of 4.94 km/s. [ABSTRACT FROM AUTHOR]