High capacity piles will support a heavily loaded warehouse for a large radiator factory in Wales.
Rig crews working to install large diameter CFA piles on a new 40m high warehouse in Newport, south Wales, are coping with limited space and challenging ground conditions.
Increasing demand for new heating systems from house builders in east Europe has created the need for Quinn Radiators' new warehouse.
Up to 500,000 radiators with a combined weight in excess of 40,000t will be stored there.
Engineers from Roger Bullivant were asked to design a piling solution that would pick up point loads from columns supporting the building and underpin a reinforced oor slab on which the warehouse would sit. Poor ground and the weight of the structure meant that each pile had to accommodate a large compression load of 1050kN.
The foundation design features a uniform grid of 574 piles, each of which extends 13m beneath the ground, and piles are created using a 600mm diameter CFA.
Each pile position is being bored using a Bullivant 7001 series rig, to auger through made ground and an upper layer of sand and gravel, before cutting through 10m of weathered Mercia Mudstone. Reinforcing cages of six T16 steel bars inserted by hand to a depth of 5m give each pile added strength.
CFA piles were preferred to precast concrete piles because of the high anticipated loadings of the new warehouse and the close proximity of neighbouring buildings.
'Precast foundations would not have been suitable for use beneath the proposed building because of the high compressive load, ' says Bullivant engineer, Jason Honour. 'In addition, the difculty of driving heavily loaded precast piles into Mercia Mudstone is well documented, and could have led to excessive settlement of the piles.'
Bullivant chose large pile diameters as this meant it would not have to bore to excessive depths. If engineers had chosen longer but narrower diameter piles, there would be a higher risk of refusal at the depths required to create the load bearing capacity.
Positions for piles to support the perimeter of the new warehouse had to be designed as close as possible to two existing industrial buildings, says Bullivant operations manager, Nick Jonathan.
'We are working as close as 900mm to one building. Piles created using a CFA create no lateral displacement of earth, so fortunately there is no risk of damaging existing foundations.'
CFA piles are being installed at 3.6m centres and rely on both end bearing and skin friction to accommodate compressive load. Tension loads will be catered for by the reinforced oor slab, which will sit on top of pile caps cast in situ.
Static tests applied to two piles using kentledge blocks conrmed the foundation could cope with 1.5 times the working load. Settlement was found to be less than 4mm and well within specication.
The latest addition to the radiator factory follows completion of a £135M extension to a manufacturing facility on site last year.
Bullivant also installed the 3600 precast piles needed to support the extension.