Performance and prediction of vacuum consolidation behaviour at Port of Brisbane

Due to a projected increase in trade activities at the Port of Brisbane, new berths on Fisherman Islands at the mouth of the Brisbane River will be constructed in the outer area(235ha) close to the existing port facilities via land reclamation. A vacuum assisted surcharge load in conjunction with prefabricated vertical drains was chosen to reduce the required consolidation time. The features of the combined vacuum and surcharge fill system and the construction of the embankment are described in this paper. A comparison of the performance of the vacuum combined surcharge loading system with a standard surcharge fill emphasises the obvious advantages of vacuum consolidation. Field data is presented to show how the embankment performed during construction. An analytical solution for radial consolidation incorporating both time-dependent surcharge loading and vacuum pressure is employed to calculate the settlements and associated excess pore pressures of the soft Holocene clay deposits.