Using the Electromagnetic Fields to observe and monitor Rock Foundation Stability at Quarter 27th City of 15th of May, Cairo, Egypt

Abstract
The site of investigation belongs to the new societies that been established on the outer extensions of the city of greater Cairo, and namely the city of 15th May City. It had been built on Eocene limestone intercalated with thin beds of clay and very thin beds of salt (Morsi at al., 2003). Generally, the Eocene limestone sediments in Egypt are characterized with karstification resulting in fractures, cracks, cavities, and land subsidence. Consequently, short after the city get in use; the city started to suffer deformations that could be evidenced on the paved roads, the successive landfalls of the foundation grounds, the water accumulation through the fissures to form swamps, and the divergence of the dwelling's blocks. Therefore; an extensive study had been conducted in cooperation of the IGF UB RAS (Geophysical Institute Federal, Ural Branch of Russian Academy of Science) and NRIAG (National Research Institute of Astronomy and Geophysics) to investigate and monitor the state stability of the foundation in a pilot area “Quarter 27”, five cycles of field observations (2008, 2010, 2011, 2012, and 2013) had been acquired along profiles crossing and intersecting the Quarter dwellings.
The analytical screening and mapping of the rock massive structure approaches to critical trends with meaningful impacts to the factor “safe” in the engineering geophysics and mining. The present work proposed the rock massive at its optimum state at the top of a ranged hierarchic structure model; and the rock massive at its present state represents a rank of disintegration or level of deformation of second grade that can be observed by electromagnetic techniques (Panin et al 1985, Sadovskiy et al 1987, Goldin 2002). In 2003, a new technique had been approached to reveal the disintegration zones in rocks of different content (Hachay et al, 2003), it involves the application of Control Source of Electromagnetic “CSEM” to image the ranked deformation levels in the massive structure. It had been devoted on monitoring a complicated engineering case at the city of 15th May, Helwan. The monitoring data had been acquired over 4 measuring cycles 2008, 2010, 2011, and 2012. The processing developed passed through several phases and conceptual proposal related to the site nature and the system of observation. The analytical treatments of the data cycles provided information about the rock massive structure and its rank of disintegration, the lateral distribution of the geotechnical heterogeneity, and finally a conclusive outcome about the foundation stability.