Geotechnical input to major bridge project

The Gateway Bridge in Brisbane, Australia, is a major structure by world standards. It crosses the Brisbane River to form a link in easterly bypass of the city of Brisbane. The total length of the structure is 1,627 m, comprising approach spans of precast two-cell prestressed concrete box girders, and a single-cell prestressed concrete cast-in-place box girder central span and cantilevers. The 260-m long central span is the longest of its type in the world. Considerable and varied geotechnical input was required for the design and construction of the bridge. The foundation conditions encountered varied locally and were highly variable along the length of the project. Foundation design changes were necessary during the course of construction and quite different foundation systems were employed along the length of the structure. These ranged from shallow pad footings on rock to deep-rock socketed piles. Approach embankment settlement problems were also encountered. Of most significance was the design of the rock socketed piles, used for the first time in the Brisbane area