BORED PILES
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| Auger Bored Piling | Driven Piling |
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| Drilled Piling | Low Noise Piling |
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| Low Vibration Piling | Self Drill Micropiles |
Bored Piles : British Aerospace
Type of pile : Augered
Number of bored piles : 140
Pile size : 250 and 300mm dia
Pile length : 16-24m
Subsequent to the installation of piling for the bases of overhead cranes in the construction of an additional production line for aircraft at Brough near Hull, British Aerospace requested Branlows to undertake further work at Broughton near Chester. Due to the success of the European Airbus, British Aerospace is expanding this facility to meet increased demand. To facilitate greater production, the existing foundations of one hangar required uprating. The hangars were built pre-war and needed structural enhancement to cater for additional loading, due to internal modifications and extra cranage capacity.
The upgrading is being achieved by core-drilling through the existing concrete bases and installing groups of 250mm and 300mm diameter bored piles to depths of up to 24m. A total of 16 bases were upgraded to cater for supplementary loads of up to 700KN per base. Rigorous load testing was carried out on preliminary piles and settlements of 1.58mm and 2.63mm were recorded at working load and one and a half times working load respectively. Recoveries of over 90% were observed, indicating that the pile movements were predominantly due to elastic compression of the pile. All works were carried out internally where access, headroom and working space to operate specialist rigs were very restricted. Branlows have also had to work around a multitude of services both above and below ground, necessitating an extremely flexible design approach. Many of bases have required individual solutions to cater for their specific problems.
As the works were adjacent to a live production area for the Airbus wings, there were also extremely tight environmental restrictions to adhere to-regarding noise, vibration, exhaust emissions and particularly dust- with strict monitoring by the client.
Branlows is also currently involved with the installation of sixty 300mm diameter temporary piles, 5m deep, to provide a 30m long contiguous piled wall retaining a 4m deep excavation. The piles are heavily reinforced using 219mm diameter steel circular hollow sections to resist the bending stresses in the propped cantilevered piles. A specially modified concrete mix is required to ensure that the tubes can be readily installed. Twenty more piles are needed to support pile-caps for temporary columns which are required for major alterations to the building frontage. These works are enabling the main contractor, Clugston Construction Ltd, to complete the excavation works more quickly and more economically than traditional methods which would have required localised traditional underpinning works in excess of 4m.
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