Mandurah Estuary Bridge Duplication â€“ Sustainable Geotechnical Design-PPT Presentation

PPT Presentation

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The Mandurah Estuary Bridge Duplication project adds a 400 m bridge alongside the existing 1986 bridge, with two piled abutments and seven piled piers. Its design must provide a 100-year service life, account for sea-level rise, and meet strict settlement and stability requirements.<br /><br />The detailed design reduced the conservatism of the reference design by reviewing historical borehole records and undertaking targeted seismic cone penetration tests. This refined understanding of the ground conditions supported replacing large bored piles with smaller driven piles, alongside driveability analysis, optimized hammer selection, and dynamic pile testing. The revised pile design used 94 piles instead of 106 and substantially reduced pile length and concrete use.<br /><br />At the abutments, the reference design’s 1,100 Controlled Modulus Columns were replaced with preload embankments. Historical monitoring data informed the design, while instrumentation and modelling verified settlement stabilization and acceptable lateral movements. Preloading also avoided complex temporary retaining works and reduced construction impacts near the existing bridge.<br /><br />Together, the design changes are estimated to avoid 7,800 m³ of concrete—about 1,000 concrete truck deliveries—and 2,500 tonnes of embodied CO₂.<br /><br />Key lessons include challenging conservative assumptions, using historical records and targeted investigations to improve the ground model, selecting low-carbon solutions that satisfy performance and construction constraints, and verifying designs through monitoring and testing to prevent overdesign and rework.

Keywords

Mandurah Estuary Bridge

bridge duplication

pile design

ground conditions

preload embankments

settlement stabilization

seismic cone penetration tests

driveability analysis

low-carbon construction

embodied CO2