A recent photo from a project we’ve been involved with, showing good progress on a hectic site in the Dublin Docklands. We’ve given support to our client Trench Control on behalf of Bennett Construction at No. 5 Hanover Quay. The tower cranes in the background give an indication of the level of construction currently ongoing in the Docklands.
The site at Hanover Quay, like many Dockland developments, includes construction of a basement and, at Hanover Quay, sheets piles were adopted as temporary support for the basement excavation. Sheet piling in Dublin is often not viable given the prevalent very stiff / hard lodgement tills (colloquially brown and black boulder clays) owing to difficulty with driveability.
However, sheet piling becomes a more viable alternative to bored concrete piling for sites moving closer to the Docklands where the boulder clays run out and the estuarine deposits become more prevalent, as indicated by Long et al. (2012), shown in the adjacent graphic. The softer upper materials can be driven through readily and groundwater cut-off can nominally be achieved in the underlying tills with a sensible sheet pile length.
In the normal run of things, there will be cost and programme benefits if an alternative to bored piling can be used. Resistance to lateral displacements can usually be achieved to an acceptable level through anchoring and / or internal propping – at Hanover Quay a mixture of both were used giving cognisance to the surrounding constraints. Read more about the project here.
Reference: Long, M., Menkiti, C., Skipper, J, Brangan, C., Looby, M. (2012) – Retaining wall behaviour in Dublin’s estuarine deposits, Ireland, Proceeding of the Institution of Civil Engineers Geotechnical Engineering. Vol. 165, pp. 351-365