Low Carbon Initiatives at Euston Station

High Speed Two (HS2) is a major high-speed railway project in the U.K. connecting London to the West Midlands. The 21 km (13 mi) of twin-bore tunnels in London include numerous geotechnical structures and extensive foundation works, such as embedded retaining walls and cut-and-cover box structures. There are approximately 1,800 rotary bored contiguous retaining wall and bearing piles in the Euston Station Approaches alone. Piles are constructed mainly in the London clay formation and Lambeth group. Some, however, were advanced to the Thanet sand formation at approximately 49 m (160 ft) from ground level. The diameters of these piles range from 750-1,800 mm (29-71 in) and most are constructed using a polymer support fluid to stabilise the soils during boring. Pile cut off level was located within the cohesive soils of the London clay with each pile reinforced with a full-length cage. Striving to achieve low carbon solutions for typical opera­tions on the site, several innovations were conceived.