Canada House, St. Stephens Green, Dublin

Nov 28, 2014

Byrne Looby recently completed the detailed design of the embedded secant pile retaining wall to accommodate the 8m deep basement for Canada House, a new office development at the corner of Dublin’s St. Stephens Green.

The city centre location, on the corner of Earlsfort Terrace and St. Stephens Green, required that our design meet tight deflection constraints due to the site’s close proximity to adjacent multi-storey office buildings and neighbouring properties. In addition due to the restricted space available on site for the proposed development, we were required to limit our pile sizes wherever possible in order to provide the largest basement footprint achievable. As a result the pile sizes varied between 900mm, 1200mm and 1500mm diameter depending on the installation location around the perimeter of the basement.

The piles were installed by Murphy International, using their powerful Bauer BG 28 rotary rig. Extremely strong limestone bedrock was encountered on site, close to the proposed basement formation level of 8.0m bgl, resulting in all piles being socketed between 2 to 3m into the underlying rock.

Due to the deflection constraints a high level propping system was required, with the main contractor M.B. McNamara Construction Ltd engaging Hegarty Demolition to install a series of Groundforce proprietary cross props to restrain the pile wall at capping beam level.

The basement excavation is almost complete, with the construction of the basement slab and internal walls and columns progressing.

The design services provided by Byrne Looby, in conjunction with the flexibility in pile sizes offered by Murphy International and the powerful rock drilling capabilities, ensured that a robust yet efficient solution was provided.