Near Surface Structures Delineation Using Geological, Geophysical and Geotechnical Techniques at the Southern Part of 15th May City, Cairo, Egypt

Abstract

The aim of the current study is to evaluate the near surface layers (lithologically and structurally) and to determine the sources which causes the recorded cracks, fractures and soil subsidence at Quarters 25, 26 and 27 at the study area. In order to diagnosis the causes of the mentioned phenomena, a detailed geological study, electrical resistivity measurements (VES and ERT), seismic survey (P-wave and MASW) and geotechnical investigation have been carried out and interpreted in integration manner. The 15th May city is located at the east of Helwan (Fig. 1) which is built on Eocene strata and the city was constructed to solve the problem of insufficient accommodation, where recent extensions had took place. The city is subjected to quarry blasts from the two quarries, one is located 1.5 km to the east direction and the other is situated 3.5 km to the south direction. Some buildings suffered cracks, fractures and soil subsidence. Geophysical applications have been used for imaging the geotechnical problems at some localities of many cities in Egypt. Many authors have used the geophysical tools to delineate the subsurface stratigraphy and structural elements. [1], investigate the stress level for the ground beneath the 15th May city. [2], apply the geophysical and geotechnical studies in pharaonic and urban areas in Egypt specially, at the 15th May and Mokattam cities, and he documents structural discontinuities in the subsurface (joints and faults), which could be a part of the geotechnical problems observed at the study areas. [3], has used the geoelectrical and shallow seismic refraction for detecting faults, fractures, caves and clay layer. [4], apply the electromagnetic imaging of the near surface dynamics and its impact on the foundation stability at Quarter 27 of 15th May city.