(A big 'Merci' to Jean-Louis Cordier for some of the photographs on this page)

Client: LTA - MRTC
Main Contractor: Bocotra Construction Pte Ltd

Shotcrete: 7,500m2
Soil Nails: 2,800 nr
Drains: 800 nr
Pipe Pile Roof: 2 x 33 pipe piles, 90mm diameter, 12m to 18m long.

The main specialist works at the site was the Shotcrete wall carried out during the main contractors excavation. As the excavation continues, a shotcrete treatment is sprayed onto the natural ground with a layer of reinforcing mesh. Soil nails are then drilled in at regular intervals as additional support and horizontal drains are provided to prevent water pressure building up behind the thin wall of sprayed concrete.

At the location of the Stamford Canal under Orchard Road Pedestrian Mall, a pipe pile roof was constructed above the tunnels to protect the structural integrity of the canal structure on shallow foundations. 33 pipe piles were drilled over each tunnel. These consisted of 90mm diameter pipes between 12m and 18m long. They are fitted with sleeves similar to the tube-a-manchette principle. The pipes are sealed to the soil by the injection of a bentonite-cement grout injected through the sleeves.