This project involved the installation of over 250 bored piles of 600- 1500 mm diameter across an extremely large site (around 75 000 m2) with ground conditions comprising variably weathered basalt rock of unpredictable thickness overlying around 10- 15 m of clays and sands, which were in turn underlain by siltstone rock.

The piled foundations were required to carry the supports for the elaborate steel-framed roof structure, which necessitated a stringent differential settlement criterion. Piles were able to be founded in the basalt rock, provided sufficient thickness and quality of rock were available.  In the event that this was not the case, the piles were founded in the sands at around 20 m depth, or in some cases drilled to siltstone at around 30 m depth. The rock sockets in the siltstone were designed using Foundation QA program rock-socket design program, ROCKET.

Because of the limited site investigation and the unconventional programming of the works, it was essential that pile design could be adjusted on site by the geotechnical engineer as the piles were drilled. The fixed occupation times and the high cost of mobilising piling equipment to poorly accessible locations made ROCKET and the Golder Associates field implementation approach, GARSP, essential tools on this project. The design efficiencies and flexibility delivered by this approach were an invaluable tool in successful delivery of the piling works, and provided savings estimated to be in the order of hundreds of thousands of dollars and tens of weeks in duration.

Special Features:

• Real-time implementation of the ROCKET approach in the field based on progressive logging of the rock sockets during construction.

For further information or general project advice please contact Dr. Julian Seidel of Foundation QA.