Avenue of Stars: removing old marine piles

Founder's project experience. Our founder took part in the construction design and site work on this project. It was carried out as part of another company's team, not under the Yan & Partners name.

The Avenue of Stars expansion needed the old marine piles under the promenade cut and taken away without damaging the structures around them. The team planned the method, the sequence and the equipment, and carried out the underwater cutting.

Method

1. Secure the pile head and fit a horizontal work frame.
2. Fit lifting straps around the pile.
3. Divers cut the pile underwater using arc-oxygen cutting.
4. The cut section is lifted onto a pontoon barge and floated out.

A purpose-made pile clamp and a temporary ladder frame gave divers safe, repeatable access at each pile. The programme ran from November 2018 into early 2019.

From the drawings

The pile schedule lists about 110 piles (B1–B99 and C1–C12), Ø1,520–1,800 mm, with seabed and pile-head levels for each and weights of up to about 40 tonnes (about 29 tonnes in water). The method: cut about 300 mm of casing at the required depth, break out the concrete to expose three or four bars per side, set up the underwater wire saw leaving the bars as temporary support, cut the bars, then lift the pile out by crane barge, or float it out from under the deck with float tanks of 60 tonnes buoyancy. We also designed an 80 m temporary drilling platform (about 88 tonnes of steel, deck at +2.20 mPD) and set out the moorings for the fountain barge on four linked sinkers.