References - Diaphragm Wall
Airport Link, Brisbane, Australia |
| Client: |
Thiess John Holland Joint Venture |
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| Main Contractor: | Thiess John Holland Joint Venture | |
| Foundation Contractor: | Piling Contractors Bauer Australia Joint Venture | |
| Scope of work: | Construction of secant piles (880mm and 1180mm diameters) and bored piles (900mm, 1200mm and 1500mm diameters) |
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| Construction Period: |
May 2009 – June 2010 |
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Construction work on the $4.8bn Airport Link project in Brisbane commenced in December 2007. This major piece of infrastrucure involves the construction of a 6.7km long road to Brisbane airport, extension of the existing Northern Busway to Kedron and the upgrading of the existing Airport Roundabout. The 11kms of tunnels require the use of two Tunnel Boring Machines (TBM). All three sections of work are due for completion by the middle of 2012. The Eastern connection to the Airport Link is to be constructed at Toombul. Within Kalinga Park a cut and cover structure is to be constructed that will form the launch box for the TBM’s and the transition structure and interchange between the bored tunnels and surface roads. To form the cut and cover and interchange structures approximately 1,100m of diaphragm walls are required. The diaphragm wall involves construction of approximately 200 panels of both 1000mm and 1200mm thickness and with lengths varying from 2800mm to 7100mm. A variety of panel shapes are to be construction including straight panels, “T” panels, “L” panels and kinked panels. The work also requires the installation of approximately 40 barrettes to provide resistance to uplift forces and foundations to the ventilation building. The depth of the diaphragm wall and barrettes ranges from 15m to 40m to suit the underlying rock profile. Excavation was performed using a combination of two hydraulic grabs and a Bauer BC40 cutter. The grabs are used to excavate soil material including fill, sandy gravels and silty clays. Once rock was encountered excavation continued using the cutter. Upon completion of excavation full depth stop-ends were installed, followed by reinforcement cages of up to 60t per panel. High slump flowable concrete was then used to form the panel. In certain panels that form TBM breakout points Glass Fibre Reinforcement (GRP) was utilized. The contract for the diaphragm walls and barrettes is scheduled for completion in March 2010. |