Settlement Prediction due to Diaphragm Walls Installation at Heliopolis Metro Station in Cairo, Egypt

Abstract

This paper presents a case history in Heliopolis, Egypt which is an underground metro station serving a high densely populated area in northeastern Cairo. This station was planned to maintain and attract density population (job-housing) in the nearby areas. The tunnel excavation and the constructed station resulted in a lateral soil displacement component and a reverse pressure affecting the side supporting system along the station sections. This displacement depends on many factors such as soil profile, subsoil properties, depth of excavation inside the diaphragm walls (Dwalls), type and stiffness of supporting system, time period of construction, surrounding structures, and surcharge loads. The present paper is comparing the observed horizontal displacement data (more than 2 years monitoring) with the corresponding estimated values of the soil model for detecting the deviation in predicted settlements in the long run and for the evaluation of any hazardous damages on buildings near excavations. It is concluded that the horizontal displacement behind the wall is about 0.06% of the excavation depth and the surface settlement is about 6 -24% of the horizontal displacement behind the wall if all construction stages are included. Also, the surface settlement is about 0.004 -0.014% of the excavation depth of the underground station.