Piling operations at Riverside Studios.

12 Mar 15

A Local Resident has raised a concern about vibration from piling. The concern raised was that a driven piling system would be used. Often significant vibration can be caused when driving steel or concrete piles into the ground. We are not using a driven piling method at Riverside Studios.

The basement levels at the new Riverside Studios development will be formed within piled retaining walls and upon a concrete raft slab built across the basement areas. There are therefore no general piled foundations below the development, only the perimeter piles. A layout drawing of the piling arrangements is available below.

The piling method we have selected is known as “CFA piling”. The Continuous Flight Auger (CFA) process is virtually vibration free and one of the quietest forms of piling, making it ideal for environmentally sensitive areas.

A continuous “flight auger” is used to drill vertically into the ground to the designed depth.

When the required depth has been reached, concrete is injected under pressure through a hollow shaft in the centre of the auger and shaft. As the auger is slowly extracted the new pile is formed. Also as the auger is extracted the displaced soils are brought to the surface and cleared.

This CFA process creates a continuous pile without ever leaving an open void or hole in the ground.

At Riverside Studios, continuous flight augering will be used to construct a secant pile basement wall to the upper basement which will be used as a propped retaining wall during general excavation and the construction of the new basement.

A secant piled wall is formed by interlocking a series of individual CFA piles. Once initial, female, piles are set with concrete, new, male, shafts are augured between them, slicing into the softer concrete of the original piles, with these new ones receiving reinforcement.

The finished result is a continuous wall of reinforced concrete which when completed with a capping beam and some temporary propping allows basement excavation works to commence.

The lower basement will be formed within a contiguous pile retaining wall. Also formed by the CFA piling method this type of wall features the piles installed close together but not interlocked, as with a secant wall.

Piling works are scheduled to commence in April 2015.