Foundation Design and Osterberg Cell Pile Load Testing in Brisbane, Australia-PPT Presentation

PPT Presentation

Pdf Summary

Waterfront Brisbane is a major development in a rapidly growing city preparing to host the 2032 Olympic and Paralympic Games. The project involves two towers, a podium and basement, built on a site with challenging ground conditions.<br /><br />The subsurface comprises very soft to firm clays, layers of sand, and foliated phyllite and greywacke of varying strength. Construction began with demolition of an existing building and installation of temporary works, including a steel combi-wall and deep soil-mixing columns. Diaphragm walls, barrettes and piles were installed using polymer support fluid. The basement was excavated in stages, with permanent slabs providing lateral support; the north tower core advanced ahead of excavation, followed by the south tower and podium.<br /><br />Heavily loaded pile and barrette foundations required reliable shaft-friction and end-bearing design parameters. Initial values were selected using engineering experience and published guidance, with verification planned through an Osterberg Cell test. The instrumented test pile was 1.2 m in diameter and used five load cells, strain gauges and other instrumentation.<br /><br />The test verified the design shaft-friction values. Ultimate friction was mobilised in soil units, while rock-unit friction was estimated through regression and assessment of the total pile capacity and its distribution. The interpreted ultimate skin-friction values were approximately 559 kPa in low-strength rock, 1,433 kPa in medium-to-high-strength rock, and 1,755 kPa in high-strength rock. Ultimate end bearing was not reached because of the rock’s strength and the test equipment’s capacity, but mobilised base pressure exceeded working-load expectations, and interpreted ultimate end bearing exceeded the design values. The interpreted rock-mass modulus was consistent with design assumptions and pressuremeter testing.

Keywords

Waterfront Brisbane

Olympic Games 2032

deep excavation

diaphragm walls

barrettes

pile foundations

Osterberg Cell test

shaft friction

end bearing

rock mass modulus