Case Study: Permanent Sheet Pile Retaining Wall, Henleys Corner

Permanent Sheet Pile Retaining Wall, Henleys Corner

Contract No:C832
Client:Tarmac National Contracting
Location:A406 North London
Value:Approximately £400,000.00
Summary:Design, supply, installation of steel sheet piles to form 2 No permanent highway retaining walls. The first wall consisted of 305 No piles (252 No at 10m long and 53 No at 8.0m long) and the second wall consisted of 66 No piles at 6.0m long to retain a maximum height of 2.60m. Once the sheet piles had been installed a concrete capping beam was cast on top of the piles onto to which a highway parapet barrier was fixed prior to backfilling with clean compacted granular fill behind the wall (Concrete, Barrier and Backfilling by others).

Sheet Piling UK Ltd were employed by Tarmac National Contracting PLC for the design and construction of permanent steel sheet pile retaining wall of both 183 Lin/m and 39.6 Lin/m long, to allow earthworks widening work to be carried out in relation to junction improvements on the A 406 in North London The sheet piles were supported by the capping beam at the top.

In total 371 no. NSP.3W/ VL 606A sheet piles at lengths between 6.0m and 10.0m long were installed using a Giken Piling SW100 Silent Piler with Water Lubrication and Full GRB System including Clamp Crane and Pile Transporter. The use of this system meant that the metal sheet piles could be installed without the need to close down any traffic lanes on the A 406 during the sheet pile installation. The specialised GRB system is particularly suited to infrastructure structure works since it allows sheet pile installation adjacent to ‘live’ carriageways or railway lines with little or minimal disruption.

The general ground profile consisted of Made Ground over Firm becoming Stiff London Clay and the sheet piles were installed using minimal water lubrication provided by the Giken Piling Super Jet Reel System. The sheet pile retaining wall was designed in strict accordance with the submitted ‘Approval in Principle’ documents for Highways Approval and an independent in-house category II design check was also completed.

Further more due to the new highways agency directive, the scheme was designed fully in accordance with the current Eurocode Standards including provision for Vehicular Impact Barrier Loadings.