OasisLMS

Abstract: As part of Dexus’ s Waterfront Brisbane project, two new high-rise towers and deep underground basement are to be constructed. The project site is located in the central business district of Brisbane, Australia, and is situated immediately at the riverbank of the Brisbane River. The basement will be supported by a reinforced concrete diaphragm wall, and the buildings will be supported by barrettes and bored piles.

The site is located predominantly within soft Quaternary age fine grained Alluvium, underlain by weathered rock of the Devonian age, Neranleigh Fernvale Beds. The Neranleigh Fernvale Beds predominantly comprise Phyllite and Greywacke and are typically of high to very high strength (UCS = 30MPa to 60MPa) beyond approximately 5m to 10m below the top of the unit.

EDG Consulting was engaged by Principal Contractor John Holland to carry out geotechnical analysis of the diaphragm wall and foundations to inform the detailed design and also to provide construction phase services. Foundation design parameters were initially selected based on our interpretation of the site geotechnical conditions and consideration of several empirically based methods available in the literature. Subsequently calculations were verified via interpretation of an Osterberg Cell load test carried out on site.

This paper presents a case study that describes the adopted foundation design methods along with our interpretation of the Osterberg cell test. Details are presented on the development of the Engineering Geological Model, the interpretation of geotechnical parameters, pile design, 3D finite element modelling of the full construction sequence, details of pile installation and a summary of predicted pile performance compared with Osterberg cell test data.

Keywords: Osterberg Cell, Foundations, Diaphragm Wall

Mr. David Cunliffe; DANIEL SCHUTT

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