Piling Devon

Project Brief: 

Dunkeswell Bridge, Devon, is a small arch based stone bridge, which has become structurally unstable caused by the increased weight and traffic. Unfortunately the road was closed until all works had been completed. The contract had to be finished in a short time, scale safely and not cause any further damage to the bridge while it was being used as a work platform.

Scope of works:

*Install 12 No. 273mm dia Steel Cased Bottom Driven Piles to a designed set.

*Insert 12 No. 150mm dia 6mm walled steel Reinforcement.

*Concrete all piles to top of capping beam.

*Leave one chosen Pile up 500m from CSL to be tested by request of main contractor.

Set up of site

The road to Dunkeswell is closed by main contractor South West Highways until all works are complete. Only pedestrians and cyclists were allowed safe passage. Barriers and welding screens were used to prevent harm to the public.

Scaffolding supports arch bridge while works continue on top.
Scaffolding supports arch bridge while works continue on top.

The arch of the bridge is supported temporarily while work goes ahead on top. Once the slab is cast over the piles, the load will be transferred to them via the capping beam, leaving the stone arch and sides of the bridge untouched.

D1000H with 750kg Piling Hammer.
D1000H with 750kg Piling Hammer.

The D1000H with built in hydraulic welder and out riggers make for a very safe machine while operating over an excavated pile position.

D1000H fitted with 200 amp hydraulic welder.
D1000H fitted with 200 amp hydraulic welder.
273mm dia Steel Cased Bottom Driven piles
273mm dia Steel Cased Bottom Driven piles

All 12 piles installed to design depth. Some of the driven piles had to be moved due to services running under the road surface. The piles either side of the bridge were also taken into account by moving them inwards, as they were displacing the ground and put pressure on the sides of the bridge.

Reinforced 273mm Driven Pile

A 150mm dia steel tube with a 6mm thick wall was inserted into each completed pile. Special skid spacers were welded to the sides of the reinforcement tube, giving the correct concrete cover. The reinforcement goes top to bottom, and is left 500mm below CSL (which is the top of capping beam). The piles were then filled with high slump, high strength concrete.

No pictures were taken of finished piles as heavy showers in the afternoon caused flash floods resulting in the road turning into a river which consequently ended in a number of piles filling with water, these were pumped out and were then ready for concreting.

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