doi:10.3850/GI125


Successful Application of Vacuum Consolidation at Port of Brisbane


Peter Boyle1, Daniel Berthier2, Geoffrey Holding3, Jay Ameratunga4,a and Cynthia De Bok4,b

1Port of Brisbane Corporation, Brisbane, Queensland, Australia.

peter.boyle@portbris.com.au

2Austress-Menard Pty. Ltd., Sydney, New South Wales, Australia.

dberthier@menard.com.au

3Austress-Menard Pty. Ltd., Brisbane, Queensland, Australia.

gmholding@menard.com.au

4Coffey Geotechnics Pty. Ltd., Brisbane, Queensland, Australia.

ajay_ameratunga@coffey.com
bcynthia_debok@coffey.com

ABSTRACT

As part of the plan to increase the capacity of the Port of Brisbane, a 235 ha land reclamation is in progress, using dredged materials from the Brisbane River and Moreton Bay shipping channels. Austress Menard was selected by Port of Brisbane Corporation to conduct a deep soft ground consolidation trial using the vacuum method along the site boundary where any instability will significantly impact the adjacent Moreton Bay Marine Park.

Ground conditions were challenging, with dredged mud reclamation up to 7m thick overlying paleochannels of soft clay up to 25 m in thickness. A unique feature in the vacuum system adopted was the 15 m deep soil-bentonite cut-off wall which was required to isolate the vacuum area because of the deep permeable layers in the subsurface profile. Coffey Geotechnics installed and monitored the extensive instrumentation program. Results were back-analyzed by Austress Menard, counterchecked by Coffey and the performance assessed by external Specialists.

The vacuum trial has been successful. The three main design objectives being achieved were enhanced stability against slip failure along the environmentally sensitive Marine Park, saving of 4m of fill surcharge and saving time on the overall consolidation process.

Keywords: Vacuum consolidation; reclamation; stability; consolidation; ground improvement.

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