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This requires a slab/beams/needles to be supported on piles and toothed into the wall of a building, divorcing it from its previous foundations. Loss adjusters frequently choose this option to overcome subsidence or settlement problems.
Combining piles and traditional underpinning makes it possible to provide deep foundations where none existed before.
Piles of suitable depth are installed on either side of the structure, or externally, in a cantilever situation (either driven, augered or contiguous flight bored) and then beams are cast between them, providing a ‘bridge’ for the structure to sit on.
This technique is used when traditional underpinning becomes uneconomic, i.e. where the suitable bearing strata is deeper than 3m and the area to be underpinned is more than 4m or 5m.
Pile Slab Underpinning - Domestic case study
Piled Slab Underpinning - Agricultural case study
Piled Slab Underpinning - Riverside Site case study
Piled Needle Underpinning case study
Piled Beam Underpinning case study
Piled retaining walls
300mm - 600mm. Retained heights up to 9m (cantilever) and 14m (propped)
Contiguous bored and secant walls, designed as either free cantilever or propped, provide a vertical face construction in dry or water-bearing soil conditions. This method of piling creates a retaining wall to restrain the strata while excavations are carried out to form basements or to maximise the useable space on a site. Piles may form part of the permanent structure or be used solely for the temporary excavation stage. Piles can subsequently be faced with brickwork for an aesthetically pleasing appearance.
If required, for instance in water bearing or granular strata, piles can be interlinked in ‘secant’ construction to exclude the water or prevent the granular material becoming dislodged during the excavation stage. Click here for examples.
Contiguous bored wall case study
Pile insertion is a quick, clean way to uprate excessively loaded industrial surfaces with minimal business disruption. The piles are installed through preformed holes in the slab and a mushroom type cap formed just under the slab to provide additional support.
Piles can also be used instead of traditional foundations to avoid damage to tree roots. The small diameter intrusion into the soil can avoid root damage and allow the tree to survive. If necessary possible pile positions can be hand dug to avoid damage to existing roots.
When used with a raft additional flexibility can be gained with the exact position of the piles. Piles can be sleeved if required to avoid concrete contamination to the roots.
If the roots are thought to be close to the surface lightweight rigs can be placed upon layers of mulch (bark) or sand and then ply sheeting to avoid point load damage.
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