Geotechnical assessment of ground conditions around a tilted building in Cairo, Egypt using geophysical approaches
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ORIGINAL PAPER
Geotechnical assessment of ground conditions around a tilted building in Cairo, Egypt using geophysical approaches Fathy Shaaban & Ahmed Ismail & Usama Massoud & Hany Mesbah & Ahmed Lethy & Abbas Mohamed Abbas
Received: 20 September 2011 / Accepted: 16 October 2012 # Saudi Society for Geosciences 2013
Abstract The flood plain of the Nile River has been a safe dwelling throughout history. Recently with a growing population and vast growing urbanization, some buildings have started to experience structural damages, which are not related to their construction design, but rather to the ground conditions around the buildings' foundations. Variations in properties of the soil supporting the buildings' foundations such as soil-bearing capacity, moisture content, and scouring may eventually lead to the failure of these buildings. This study is attempting to characterize the variations in the soil properties around the City Star shopping mall, in eastern Cairo, where a large building has tilted over the past few years. This tilting may lead to the collapse of the whole building if it continues at the same rate. An integrated geophysical investigation including multi-channel analysis of surface wave (MASW), ground-penetrating radar (GPR), and 2-D electrical resistivity tomography (ERT) was used around the affected building to help detect possible causes of deterioration. The GPR data showed a soil-filled layer overlaying a thick bottom layer of higher moisture content. The MASW data revealed a middle layer of relatively low shear wave velocity sandwiched between two relatively F. Shaaban : A. Ismail : U. Massoud : H. Mesbah : A. Lethy : A. M. Abbas National Research Institute of Astronomy and Geophysics (NRIAG), 11722 Helwan, Egypt A. Ismail Illinois State Geological Survey, University of Illinois at Urbana-Champaign, Champaign, USA F. Shaaban (*) Department of Physics, Faculty of Science, King Khaled University, Abha, Kingdom of Saudi Arabia e-mail: [email protected]
high shear wave velocity layers. The ERT data showed an upper low resistivity layer overlying a high resistivity layer. Integrating the interpretations of the three geophysical methods provides a combined model that reflects lateral and vertical variation in the soil properties. This variation becomes dramatic near the tilted corner of the building. Keywords Multi-channel analysis of surface wave . Groundpenetrating radar . Electrical resistivity tomography . Geotechnical investigation . Greater Cairo . Egypt
Introduction Using noninvasive geophysical techniques for near surface characterization of geotechnical sites has grown rapidly during the last few decades as information derived from borings has become costly. Geophysical techniques which are commonly used for geotechnical site investigation include seismic reflection and refraction (Cook 1965; Steeples and Miller 1987), seismic surface waves (Ismail and Anderson 2007), ground-penetrating radar (Ballard 1983; Annan et al. 1991), and electrical resistivity tomography (Griffiths and
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