Construction Challenges
Once the project was awarded, teams were on the ground immediately to begin the fast tracking of the construction. The first and most critical task was to secure the building footprint. The entire complex sits on 0.56 million square meters (6 million square feet) of reclaimed land – sand infill on deep soft marine clay deposits. Marina Bay is a former salt water estuary that is now a fresh water reserve. Prior to excavation, the site needed to be reinforced. In order to do this, 1.5 meter thick (5 feet) steel-reinforced concrete diaphragm walls (coffer dams of up to 120 meters or 394 feet in diameter) were extended 50 meters (164 feet) into the ground providing an enclosure for excavation.
The key challenge of building the hotel towers was the construction of the part of the towers that slope at an incline. Unsupported, they could buckle under their own weight. The sloping leg induces an enormous external force onto the structure, which needed to be addressed during construction.
The structural engineer conceived of an approach to build large temporary struts of structural steel to prop up the sloping towers as they rise (see Figure 10). Like a suspension bridge, high-tensile steel tendons give an added layer of support inside the walls. Both the struts and the tension cables were designed as temporary supports and planned to be removed once the giant linked trusses that connect the towers on the 23rd floor were installed. However during the construction process it was decided that the cables would become permanent.