Building on Soft Ground: Naue Combigrid® & Secugrid® at Collins Wharf

Project Background

Collins Wharf by Lendlease is an exclusive new waterfront location under construction within Victoria Harbour, Melbourne. Comprising two high-rise buildings named Regatta and Ancora, Collins Wharf is a luxurious residential development offering a range of waterfront apartments and town houses featuring views of the Yarra River and Victoria Harbour. The development is designed to provide a tranquil yet urban lifestyle, with easy access to the heart of Melbourne.

The Challenges

The Docklands area of Melbourne is comprised of Coode Island Silt (CIS). Due to its low bearing capacity and high compressibility, CIS is one of the most problematic soils to construct on. In addition to the challenges of CIS, the Collins Wharf development would be constructed on the site of the former port with areas of surficial concrete and decommissioned utilities. To construct hardstands and working platforms suitable for the piling rigs would require enormous quantities of crushed stone, at high costs in terms of materials, labour and construction time.

The Solution

The geotechnical and foundations designer proposed hardstands and working platforms which incorporated a layer of Naue Combigrid® on the subgrade and an intermediate layer of Naue Secugrid®. The proposed Combigrid® & Secugrid® design would significantly reduce the amount of imported granular material and its associated costs, as well as offering significant reductions in embodied carbon. Combigrid® & Secugrid® have exceptional stress-strain behaviour at low elongation making them a perfect choice to address the low bearing capacity of the weak subgrade. Furthermore, due to their low elongation, Combigrid® & Secugrid® have been proven to be well suited for subsequent piling operations.

Materials were available from stock allowing contractor Fitzgerald Constructions to swiftly construct the hardstands and meet project timescales. A total of 5,700m2 Combigrid® and 7,000m2 Secugrid® were supplied to the prestigious project.