UK FOUNDATION contractor Aarsleff Piling supplied and installed more than 800 of its precast concrete piles ahead of programme for a precast concrete tunnel segment factory at Ridham Dock, north Kent.
The £4M factory is being built for Miller Tunnelling which identified a gap in the UK market after Taylor Woodrow decided to close down its tunnel segment factory in Southall, Middlesex.
Aarsleff used two of its Swedish-built Banut 500 self-erecting, hydraulic drop hammer leader rigs to drive 15m to 22. 5m long reinforced 250mm square section piles through fill and alluvium and into the underlying stiff London Clay. The precast piles were supplied in up to 17m long sections, which were joined on site using rigid pretensioned mechanical steel joints to maintain pile integrity.
The piles were installed for the main factory building, offices, batching plant, aggregate bins and stockyard overhead gantry crane rails. Pile working loads vary from 130kN to 530kN.
Working closely with Miller Tunnelling, Aarsleff was able to select the most appropriate pile to meet the loads, driving conditions and the tight construction programme. The company managed to knock 25% off the programme to complete piling for the main building in only six weeks.
'This enabled us to get on to the groundworks and steelwork erection much earlier than anticipated, ' said Miller Tunnelling project manager Ian Heath. Aarsleff completed its £380,000 contract by the beginning of June.
Once one of the UK's three tunnel segment manufacturers, Taylor Woodrow had a 40% share of the country's tunnel segment market, estimated to be worth about £30M. Many of the firm's staff have since moved to Miller Tunnelling.
The new precast yard has direct access to the docks and a railway siding, allowing raw materials to be imported by sea, rail or road, and transportation of finished segments throughout the UK and Europe.
When production starts in December 2001, Miller will offer a total package to drive, install, and supply tunnel-lining segments for large tunnelling contracts.