BORAL CONCRETE PLANT
Granville, NSW
Secant/Contiguous Piles
Project Description
Boral are upgrading their concrete plant in Granville to deal with the additional demand expected in that location caused by the upgrades of the M4 and M5 motorways that run east/west out of Sydney. AFS were contracted to install a CFA Secant Pile retaining wall for the new materials bins at the concrete batch plant. The project consisted of 179 total piles with 91# soft primary piles (10MPa late age) and 88# hard secondary piles (40MPa).
Solutions
The long rock sockets and soft piles extending into rock presented the issue of how to keep the hard piles vertical instead of them wandering into the soft pile once the harder rock was encountered. To counter this, the polystyrene pods used in the guide wall were reduced in diameter while the auger string was built up to ensure a tight fit in the guide wall to fix the auger string at the top of the pile. Also the operator was instructed to slow down the drilling speed for the first 1m of the rock socket while the offsider checked the verticality of the auger every meter through the socket.
