Huyton Railway Station, Liverpool
Part of the upgrade of Huyton Railway Station was to construct a new underpass below the tracks. To achieve this, the level of the footpath at the toe of the existing retaining wall had to be lowered. This had the effect of increasing the retained height of the wall with a corresponding increase in both earth pressure and overturning momentum. To balance this increase 12m long drilled and grouted soil nails were originally specified. However, a ground survey indicated the presence of a live gas main 8m behind the wall which could not be relocated.
Platipus Percussion Driven Earth Anchors (PDEA®) do not rely on skin friction so an alternative shorter anchor design became an option. Following vertical suitability testing behind the wall, Platipus created a Conceptual Proposal and Indemnified Design that would achieve the loads required and, most importantly, ensured the anchor embedment depth finished short of the gas main. Aluminium bronze B10 anchors with 20mm Ø stainless steel threaded bar and stainless accessories met the required 120 year design life. Platipus trained the main contractor in the safe installation of the anchors. On completion, a new skin of brickwork was built to cover the load plates.