60 Dawson Street (Project Kells): Precision geotechnics for a major double-basement in Dublin City Centre

60 Dawson Street is a landmark retail and commercial space in the heart of Dublin. The mixed-use development consists of 7,432m² of retail space and approximately 9,290m² of office space over a two-level basement. This premium city centre location presented significant challenges due to the presence of Dublin’s light rail system running adjacent to the site. The project involved the demolition of several existing structures on site and the construction of seven new floors above the double basement, providing 145,000 sq. ft. of Grade A office space and 46,000 sq. ft. of retail space. Excavations were completed to a depth of 9.5m across the full site area, with 25,000m³ of excavated material removed.  

Ayesa was appointed by the piling and anchoring subcontractor PJ Edwards & Co Ltd., working on behalf of John Sisk, to carry out the detailed design of the perimeter secant pile wall, foundation bearing piles, and the temporary tieback anchors. The site is bounded on two sides by roads and existing buildings. Tracks and overhead lines for Dublin’s Luas transit system also run alongside the site. The project required precision engineering to accommodate the live Luas line, necessitating detailed finite element method (FEM) modelling of the basement interaction with the track. Our team used Plaxis to ensure the design minimised risks to the tram line and adjacent buildings. The design solution included a stiff and robust temporary propping system to minimise pile wall movement, and wayleave access rights were obtained to install temporary ground anchors under the public domain. Active props were adopted elsewhere to achieve a stiff propping system, ensuring that pile wall’s lateral movement during the basement excavation works was within FEM predictions. The curved corner section of the secant piled wall is tied back under the Luas lines by permanent 15m long ground anchors installed at an angle of 45 degrees.

The design solution required a stiff and robust temporary propping system to minimise pile wall movement and mitigate risks to the Luas lines and adjacent buildings. The implementation of wayleave access rights allowed for the installation of temporary ground anchors under the public domain. Both temporary support systems were designed to conform to minimum system stiffness requirements, ensuring that the pile wall’s lateral movement during basement excavation was within FEM predictions. The completed building features seven floors above ground and a two-level basement with a substantial light-filled atrium at the centre of the superstructure, including underground parking and amenities.