Retaining wall and foundations for 36-storey property with four basement levels.
The twin 150m-high towers of the riverside Nile City complex on the Nile in North Cairo will house offices, apartments, a business centre cinemas and a shopping mall, with four basements levels for parking and services.
Nile City Investments
The difficult geology at the site called for a range of specialist construction techniques, provided by Soletanche Bachy Egypte (a former subsidiary of Soletanche Bachy) under separate and joint contracts.
The specialist works required comprised the excavation of a 16,000 m2 area to a depth of 14m, and deep foundations for the towers and other structures.
The ground conditions (water table 4m below surface) and great thickness of alternating sands and clays called for the following works:
The strict construction tolerances on these supports, the fast work rates dictated by the tight schedule and the special geotechnical features meant that the Hydrofraise® 4000 had to be assigned. The substructure elements, built from ground level, were 41m deep and concreted over a height of 27m.
The less heavy structures sit on 1.00m and 1.20m bored piles reaching a depth of 38 metres. Productivity driven by the tight schedule for the foundation works peaked at 800 m3 per day with as much material to be removed, and three concrete plants allowed the concreting rate to reach 500 m3 per day.
All the work was fully monitored:
– All diaphragm walling and barrettes were checked for thickness and tilt with Kodesol ultrasound apparatus
– A combination of systematic Kodesol tests and the Enpafraise® continuous monitoring system made it possible to meet the stringent verticality requirements in the specifications, limiting tilt to 0.75% at 40m depth.
Several prior loading tests were made on the barrette piles up to 3000t with a ground anchor beam reaction system.
14,099 m² excavated area
Barrettes (depth 41m)
Piles (depth 38m)