Fisherman Islands GPB,
Port of Brisbane Corporation has engaged Menard Oceania through the Menard Oceania & Civdec Constructions Joint Venture to complete the Rockwall and General Surcharging
Contract as part of the construction of the new Port of Brisbane General Purpose Berth located on the Brisbane River at Fisherman Islands. The project involved the reclamation of the Brisbane River with the construction of a rockwall, filling, installation of stone columns and wick drains and surcharging.
The ground conditions were predominantly marine muds overlaid by imported and consolidated river sands. The site also contained potential acid sulphate soils.
Stone Columns, Vibrocompaction, Wick Drains
1,450 stone columns were installed along the length of the rockwall to a treatment zone 15m wide over 360m of the reclaimed river, with an average depth of 15m, and a maximum depth of 21m, some 16.5m below the water table.
Menard Oceania mobilised two top feed wet method vibroflots to complete the works. The technique involves the use of a vibroflot, comprising a hydraulic powered eccentric weight assembly enclosed in heavy tubular steel casing. The vibroflot(8m length) is suspended from a crawler crane. The nose of the vibroflot is tampered to aid penetration of the ground, whilst vertical fins prevent the vibroflot rotating during penetration. The compacted column is formed composed of imported crushed rock mixed with the original soil. The fill material is simultaneously pressed into the surrounding soil and compacted in 0.3m to 0.5m lifts until the stone column is formed to the surface.
