References - Diaphragm Wall
Tugun Bypass Motorway, Tugun Australia |
| Client: |
Main Roads |
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| Main Contractor: | Pacifik Link Alliance consisting of Main Roads, SMEC Pty Ltd and AbiGroup Pty Ltd |
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| Foundation Contractor: | BAUER Foundations Australia Pty Ltd | |
| Scope of work: | 16,500m2 Diaphragm Wall with width 1000mm and up to 27m depth and 3,200m2 (60 nos) Barrettes with width 1000m and 19m depth. |
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| Construction Period: |
April 2006 – October 2006 |
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To ease traffic congestion at the Tugun merge of the Pacific Highway and the Gold Coast Highway a new Motorway was constructed. The Tugun Bypass project is a high standard 7km road link between the southern Gold Coast and northern New South Wales. The $360m project includes a 400m Tunnel beneath a proposed extension of the Gold Coast Airport runway. For construction of the tunnel two 400m diaphragm walls were designed; one wall for the northern side of the carriage way and one for the southern side. In the centre line of the tunnel 60 nos barrettes were installed using the diaphragm wall method. As the construction of diaphragm walls is a very specialized procedure, this part of the project was assigned to a Sub-Alliance which was made up of a joint venture between Bauer Foundations Australia and Piling Contractors. Because the extension of the runway for the Gold Coast Airport was proposed over the new bypass, it was necessary to construct the tunnel under the new runway. As the site of the new tunnel is directly adjacent to the airport, headroom restrictions applied due to taking off and landing planes. The Obstacle Limitation Surface (OLS) which were imposed by the Gold Coast Airport varied from 6.5m to 12.5m. Special equipment was necessary to comply with the headroom restriction near the airport. Bauer Foundations Australia could provide a low headroom grab, a special BAUER CBS 25 cutter as well as other low headroom equipment (e.g. tremie pipes). Reinforcement cages were installed in 3 (19m) or 4 (27m) sections. In order to connect the roof and base slab to the diaphragm walls at a later date coupler boxes were mounted onto the cages. |