290No. Arcelor PU22-1mm 9.5 to 11.0m long in Grade S355GP
Gravelly Sand over London Clay
Fussey Piling Limited (01608 659595) have recently completed the first stage of a steel intensive basement for Giggs Hill Homes in Thames Ditton, Surrey.
The project involved the construction of ten properties and an underground car park.
The basement car park, on this interesting project, was initially designed as a contiguous piled concrete wall. However, after a series of design changes sheet piles were employed throughout to provide a cost effective basement solution for the client and developer, Giggs Hill Homes.
Fussey’s involvement in the project started when they were asked to provide an alternative design solution to the originally envisaged scheme. At tender stage the basement was a straight forward cofferdam. However, following discussions with the client the sheet piles had to be designed to take vertical loads of up to 200kN/m in places. Sheet piling is often a quicker and more environmentally friendly basement solution especially in a town centre location, such as this.
Fussey’s Contracts Manager, Graham Hall, said ‘the ground is well suited to a sheet piled alternative. The ground conditions encountered were superficial deposits of clay to 1.5m overlying sand and gravel to approximately 3.0m before entering the London clay. The London clay horizon helps provide excellent skin friction to enable the vertical loads to be accommodated without adding significantly to the over-all cost of construction’.
The sheets were installed ahead of programme, in just 19 working days, using one of Fussey Piling’s Kowan Stillworkers, serviced by one of Fussey’s Sennbogen 630HD Telescopic Crawler Cranes. This is an exceptionally short programme period when one considers there were 11 corners to turn in the cofferdam.
The sections used varied from 9.5m to 11.0m PU22-1mm piles steel grade 355GP, retaining a maximum height of 5.0m. The sheet piles were supplied by Arcelor Mittal from their Shoreham stockholding facility and are made from 100% recycled steel.
Once the sheets had been installed the next stage was to install the concrete bearing piles for the rest of the super structure. Upon completion of the concrete piling and excavation of the basement Fussey Piling returned to site to weld up the exposed pile clutches to ensure a water-tight basement environment.