Design and construction issues of the soft-eye headwall for Brisbane AirportlinkM7's 12.48m diameter tunnel boring machines
The Tunnel Boring Machine (TBM) launch box for the Brisbane AirportlinkM7 consists of diaphragm walls with the use of both steel and reinforced concrete for the various levels of temporary and permanent props and whalers. The launch box was constructed in a top-down sequence to a depth of approximately 23m, which resulted in the 1.2m thick concrete sections being heavily reinforced. Glassfibre reinforcement was required in the soft-eyes to allow for the launching of the two TBMs through the headwall. Under lateral loading predominately arising from soil and water pressure, the glass-fibre reinforcement needed to resist the short-term loading until the TBM’s were launched. The permanent regions of the diaphragm wall above and below the soft-eyes required steel reinforcement to satisfy the long-term loadings and to meet the 100 year design-life requirements. The use of the glass-fibre reinforcement entailed several design issues that had to be dealt with, including: a low modulus of elasticity and shear strength of the material, creep effects and limited ligature shapes. Three-dimensional analysis was undertaken to optimise the headwall design in both the short and long-term conditions. The quantity of reinforcement, which was required to withstand the temporary loading, has led to significant construction constraints, especially with congestion of the GFRP and steel reinforcing at the interfaces between the soft-eyes and the permanent headwall. Careful detailing, a close working relationship with the contractor and a strong, engineering site-presence during construction, allowed for the successful integration of the design and constructability requirements.
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Authors:
- Donohue, J
- Eberhardt, R G
- Juhasz, I
- Conference:
- Publication Date: 2013-10
Language
- English
Media Info
- Pagination: 7p
- Monograph Title: Concrete 2013: understanding concrete: 16-18 October 2013, Gold Coast, Queensland, Australia
Subject/Index Terms
- TRT Terms: Construction equipment; Drilling; Equipment; Fibers; Glass; Material reinforcement; Reinforced concrete; Tunnels
- Uncontrolled Terms: Road design and asset management
- Geographic Terms: Australia; Brisbane, Queensland
- ATRI Terms: Construction equipment; Drilling; Fibre; Glass; Reinforced concrete; Reinforcement; Tunnel
- Subject Areas: Bridges and other structures; I25: Design of Tunnels; I32: Concrete;
Filing Info
- Accession Number: 01514722
- Record Type: Publication
- Source Agency: ARRB
- Files: ITRD, ATRI
- Created Date: Feb 20 2014 10:14AM