NUMERICAL MODELLING OF SUBWAY STATIONS IN GREATER CAIRO FORMATIONS

Abstract

Analysis of deep braced diaphragm walls subjected to sequential excavations coupling with grouting processes to control hydrostatic pressure and seepage forces of the groundwater outside the diaphragm walls is considered as one of the most sophisticated soil-structure interaction problems. The cut-and-cover construction technique for the construction of subway stations utilizing deep braced diaphragm walls is considered as an effective method for controlling the ground subsidence associated with the construction activities and ensuring the safety measures for the nearby structures and utilities. The main objective of the present study is to numerically evaluate the behavior of a subway station constructed utilizing braced diaphragm walls through typical Greater Cairo water-bearing alluvial deposits. Rod El-Farag subway station, which is one of the Line 2 – of the Greater Cairo Metro, is used in the analysis of the proposed model. Both the soil and the diaphragm walls were extensively instrumented during the construction stages to report the ground subsidence around the station, as well as the mode of diaphragm walls deformation. 2D and 3D finite element analyses were employed to simulate the different stages of construction. The computed back-analyses of the both idealizations were compared with the field measurements compiled during construction phases. Finally, a parametric study concerning some of the important factors which affect the soildiaphragm walls-construction sequence interaction was conducted, and the results were discussed. III ACKNOWLEDGEMENTS First, thanks to Mighty ALLAH who helped me through all days of work and on whom I always depend, and by having faith in him, he always fulfills my wishes. The author is very grateful to Prof. Dr. Ali Abd El-Fatah, Professor of Geotechnical Engineering, Faculty of Engineering, Ain Shams University, Cairo, for his constant guidance and precious advice. The author is very grateful to Dr. Eng. Ashraf Hefny, Associate Professor of Geotechnical Engineering, Faculty of Engineering, Ain Shams University, Cairo, for his valuable assistance and guidance. The author is very grateful to Dr. Eng. Mohamed Farouk Mansour, Assistant Professor of Geotechnical Engineering, Faculty of Engineering, Ain Shams University, Cairo, for his due patience and being the backbone of this work. Of course, the author doesn’t know how to thank Prof. Dr. Fathalla Mohamed El-Nahhas, Professor of Geotechnical Engineering, Faculty of Engineering, Ain Shams University, Cairo, for being a great father and a kind teacher for all of us. The author appreciates the support and good remarks of Prof. Dr. Ahmed Hosny, Professor of Geotechnical Engineering, Housing & Building National Research Center, Cairo, for his constant guidance and precious advice. A special thank you for Dr. Ayman Lotfy Fayed, Associate Professor of Geotechnical Engineering, Faculty of Engineering, Ain Shams University, Cairo, for being a great brother, teacher and support of life. The author is very thankful to all his family members for their support, care, advice and encouragement