Third Runway: pile-cap cofferdam and watertight formwork
A temporary-works scheme for casting marine pile caps at the Third Runway: a sheet-pile cofferdam, a steel trestle and a 62-tonne watertight formwork lowered over each pile group.
- Year
- 2020
- Client
- Gammon Construction
- Location
- Hong Kong International Airport
- Status
- Method design (tender stage)
- Category
- Temporary works
Marine pile caps are cast just above the waterline on groups of steel piles. For the Third Runway we drew two ways of doing it.
Cofferdam. Larssen III sheet piles, about 280 pieces of 12 m (about 256 tonnes), walings at +4.5 and −1.0 mPD, and a steel trestle carrying a crawler crane on 914 × 305 and 914 × 419 UC beams over 610 × 229 UB posts. About 1,354 m³ is dredged and backfilled.
Watertight formwork. For a group of fifteen 610 mm piles, a steel formwork of about 62 tonnes is lifted over the group by derrick barge. Water-stop collars and pile-head plates seal it, the base and side panels are stripped in stages after the pour, and the formwork moves on.
The scheme was prepared with full quantities and weights at tender stage.
Drawings
