Steel piles had to be squeezed into space behind retaining walls as part of a rail electrification programme.
Steel foundations specialist FLI Structures of the Haley Group recently installed screw pile foundations to support overhead line electrification work on the Great Eastern Line for Carillion on behalf of Network Rail.
FLI was contracted to design, manufacture and install 20 bases consisting of mast and tie & strut foundations. The project presented several challenges. Most of the foundations were to be installed behind fragile Victorian retaining walls and the brief was to avoid overloading them. Ground conditions were challenging with a high water table and running sand in some areas.
Available space for placing the foundations behind the retaining walls was very limited, especially as the foundations had to avoid retaining wall footings, adjacent footpaths and fences. Finally, work was to be carried out in possessions during day or night shifts in a built-up area where noise levels had to be kept to a minimum. As a result, screw piling was the best and probably the only solution.
FLI designed a range of bespoke screw pile foundation solutions to cater for varying gantry spans and loads. Groups of screw piles with pile diameters up to 219mm were selected and installed up to depths of up to 7m.
FLI installed the screw piles using plant with torque motor attachments. The installation process is quiet as driven impact hammers are not required. The retaining walls were unaffected.