Gpile

7 December 2005
Our Reference 0301458

Mr Mike Vadasz
Australasian Piling Company 3 Thompson Street
DRY CREEK SA 5094

Dear Sir

Re: Use of the G-Pile Method in Australia

The writer confirms involvement in the geotechnical engineering aspects of the G-pile piling method since its introduction into Australia in early 1998.

This piling method has been used in a variety of geological conditions ranging from soft and stiff clays, loose and dense sands and gravels, and weathered rock in various projects in NSW, Victoria, Queensland, South Australia and Western Australia.

The G-pile method is a type of jacked pile and falls under the classification of a "preformed displacement pile" by AS 2159 "Piling - Design and Installation Code", Section 1.7.2. However, the method has many advantages over conventional driven preformed displacement piles such as:

No vibration is associated with its installation.
Minimal noise is generated during installation.
By the method of installation, each pile is effectively proof loaded to failure during construction so that greater confidence is obtained in the assessment of the pile's load carrying capacity.
Minimal spoil is created during piling, so in contrast to several other piling methods, much cleaner site works are associated with the G-pile method.

The G-pile method has been carried out for the following major projects:

Rivergardens Project (23 Stories), Southbank, Melbourne. This involved soil conditions comprising soft Coode Island Silt, overlying Melbourne Mudstone with pile depths up to 36m.
Burswood Resort Casino Extensions, located adjacent to the Swan River, Perth. This involved piles to a depth of 36m in soft alluvial soils.
Adelaide University Redevelopment Projects (3 separate building projects). This involved piling through River Torrens alluvium including a layer of dense gravels over Blanche Point Formation.
Sydney International Airport Extensions, NSW. This involved piling through sands to a depth of up to 18m.
Redfern Residential Apartments, NSW. This involved piling through loose marine sands and clays into weathered shale up to about 10m depth.
Fairy Meadow Aldi Store, NSW. Timber friction piles were used to support the structure on firm to stiff clays.
Holdfast Shores Residential Development, North Glenelg, South Australia. Series of large residential buildings founded on steel piles driven through reclaimed land over loose sands and into stiff clays up to about 15m depth.
Colley Terrace Apartments, Glenelg, SA. A multi-level apartment building founded on piles driven through loose sand over stiff clay up to about 15m depth.
St Ignatius College Junior School Extensions, Norwood, SA. A major redevelopment of a school building supported on piles driven through fill and founded on stiff clays and gravels.
Pretoria Hotel Extensions, Mannum, SA. Piling for a large redevelopment over very soft clays over weathered limestone at depths varying from 5m to 35m.
400 tonne Flyash Silo for Adelaide Brighton Cement, Birkenhead, SA. Steel tube piles driven into a founding layer of stiff clay at about 25 m.
3-Level extension to Sydney Cricket Ground, NSW. Timber piles driven to found in dense sands.
Queen Elizabeth Hospital Redevelopment Project. This involved 185 mm precast concrete piles driven through firm to very stiff clays to depths of about 12 m.
Perth Convention and Exhibition Centre. This involved soil conditions comprising deep soft normally consolidated clay overlying stiff clay overlying siltstone bedrock at depths up to 37 m.
Gold Coast Convention and Exhibition Centre. Piling involved precast concrete piles founded on very dense sand up to 10 m depth.
Forster Apartment Building, NSW. Ten storey apartment building on precast concrete piles founded in very dense sand at 8m depth.
Newcastle Centro Polyclinic, NSW. Five storey building on 400 mm square precast concrete piles founded in rock at around 30 m depth.
Maitland Apartment Building, NSW. Four storey apartment building on 185 mm square precast concrete piles founded on a dense granular layer.

The types of preformed piles have included precast concrete piles of sizes varying from 185 mm square to 450 mm square, hollow steel tube piles jacked closed-ended and hearted with reinforced concrete, and hardwood timber=piles.

Several recent technical publications have been prepared. These would be of interest to geotechnical and structural engineers involved in jacked piling.

Mitchell, P. W. & Mander-Jones, J. "Experiences with Jacked Piles". Australian Geomechanics. Vol.39, no.4, pp. 11-24, December 2004.
Mitchell, P. W. "Jacked Piling in a Soil Subject to Relaxation". Australian Geomechanics. Vol. 39, no.4, pp. 25-31, December 2004.
Mitchell, P. W. "Bearing Capacity of Jacked Piles in a Layered Soil Profile". Australian Geomechanics Vol. 40, no. 2, pp. 89-98, June 2005.

Yours Faithfully

Peter W. Mitchell
Senior Principal Geotechnical Engineer
URS Australia Pty Ltd