Installation of a new horizontal boring machine for machining precision parts at the Nuclear Advanced Manufacturing Research Centre (NAMRC) in Sheffield has called for some innovative ground engineering solutions.
Main contractor Richlea Developments called on Groundforce Shorco to develop temporary support design to build the piled concrete base for the boring machine at Waverley Technology Park.
Foundations for the base have been formed using 78 600mm diameter auger-bored concrete piles at 2m centres, which were drilled from the underside of the existing floor slab level before work started to excavate the surrounding material.
Groundforce used a mix of its Mega, Maxi and 900 series braces and sheet piling to support the T-shaped based excavation, which measures 35m in length and is 18m wide at the widest point. The depth of the excavation varies from 3.1m to 4.9m.
According to Richlea, the use of Groundforce’s modular piling helped to minimise obstructions in the excavation which was already crowded by the closely spaced piles.
After reaching the required depth, Richlea cast the blinding slabs to enable lower frame removal before fixing the reinforcement and pouring the main base slabs, using the trench sheets as temporary formwork. To prevent the concrete bonding to the steel sheet piles, Richlea sprayed a sacrificial layer of foam onto the inner surface before the pour. After the concrete had cured, the building’s own 50t overhead travelling crane was used to extract the piles.