Permanent Sheet Pile Retaining Walls

Sheet Piling (UK) Ltd is a leading specialist in the use of steel sheet piles which form permanent sheet pile retaining walls on a wide variety of schemes and applications.

Typically, steel sheet piles are specified and installed as the permanent retaining structure on schemes where insufficient space is available for complex temporary works, which would otherwise be required. Such temporary works are often intended to allow for the construction of alternative retaining solutions or are used where the cost and programme benefits of permanent sheet piling are too high to make it the chosen retaining solution.

On road and rail infrastructure projects, sheet piles are designed in accordance with relevant Highways Agency or Network Rail design standards, as well as being supplied with associated design and checking certification. Usually, these specifications require a design life of 120 years, together with a surcharge loading relevant to the proposed application (i.e. Highway HB loading or Railway RU loading).

Other common applications include retail and commercial service yards, flood defence walls, axially loaded bridge abutments and boundary retaining walls for residential developments.

Sheet Piling (UK) Ltd’s experienced in-house design engineers are able to offer a full design service for such schemes, including the relevant Approval in Principal or Form B documentation. The service also comes with independent checking (where applicable).

An alternative to a traditional sheet pile retaining wall is a King Sheet Piling (KSP) retaining wall which utilises pairs of Z section piles as ‘Kings’ with lighter and shorter Z piles as ‘intermediates’ spanning horizontally between them.

On certain projects the use of KSP retaining walls can provide steel savings when compared to the cost of a traditional retaining wall solution. There are also some environmental and constructability benefits. However, the designers of a KSP wall need to consider the reduced stiffness, which can have a significant impact on wall deflections.

Permanent sheet pile retaining walls are generally designed using Z Section Sheet Piles which deliver the benefit of high-strength to low weight ratio. Typically, Z-section sheet piles will be supplied by Arcelor Mittal or Emirates Steel since both steel manufacturers have BES6001 Responsible Sourcing of Construction Products which is mandatory when working on public sector projects.

Once installed, sheet piles have an immediate and structural capacity, allowing excavation to commence immediately and generating no spoil – as is the case with alternative secant and contiguous pile walls. If required, the exposed sheet piles can be shot-blasted and painted, to provide an aesthetically acceptable finish and enhance the pile section design life. Alternatively, a wide range of ‘non-structural’ cladding solutions can be constructed in front of the wall.

In addition, a reinforced concrete capping beam can be cast to the top of the permanent sheet pile retaining walls, to allow any containment barriers / hand railing to be directly affixed. Alternatively a steelwork capping beam can be specified.

Finally, to prevent build-up of excessive hydrostatic water pressures behind the sheet pile wall, drainage weep holes are formed nominally above the final excavation level. On critical applications, where preventing loss of fines through the weep holes is key, and the relief of any hydrostatic pressures vital, consideration should be given to the use of the unique ‘Blue Marlin Weep Hole Filter System‘.

Some recent successfully completed permanent sheet pile retaining wall projects, carried out by Sheet Piling (UK) Ltd, are listed below: