Seafarers, Northbank Precinct

The challenge.

The Seafarers redevelopment integrates an existing heritage goods shed into a new mixed-use tower on the northern bank of the Yarra River in Docklands.

The site is underlain by a relatively complex sequence of Quaternary age Yarra Delta alluvial sediments, including deep, low strength estuarine soils, with bedrock in the order of about 30 m below ground surface.

The subsurface conditions, in conjunction with the proximity of the proposed tower to the Yarra River, presented a number of challenges for the proposed development, with lateral ground movements required to be tightly controlled during both basement excavation and piling works to minimise impacts to the adjacent wharf and heritage structures.

The approach.

FSG provided geotechnical advice and recommendations on subsurface conditions, footing systems and basement retention options for the proposed development, following consolidation and review of historic site investigation data.

We designed a temporary working platform to support piling works and assisted the building and early works contractors with developing a sheet-piled tie-back wall system to retain and limit movements of the existing wharf structure and heritage listed good shed during construction.

Numerical soil-structure interaction analysis was undertaken using PLAXIS 2D and 3D to assess the performance of the tie-back wall system. The numerical modelling incorporated detailed demolition and construction staging sequencing and evaluated the effects of concrete overbreak and oversupply within soft ground conditions on sheet pile wall behaviour during piling operations.

The outcome.

FSGs geotechnical advice and analysis supported the safe and efficient delivery of the early works package while protecting critical existing assets. The resulting temporary and permanent works strategy enabled the builder to undertake construction activities with minimal impact on the existing wharf and heritage-listed Goods Shed. Lateral ground movements during construction and piling works were maintained within acceptable limits, with survey monitoring confirming the performance of the temporary retention system and the protection of adjacent structures throughout the works.