Foundations of the Annacis cable-stayed bridge

A new highway crossing of the Fraser River at Annacis Island near Vancouver, British Columbia, is currently under construction. It involves a major cable-stayed bridge with a main span of 465 m. Support for the bridge is provided by piles driven into dense overconsolidated Quaternary sediments: on the south bank they are found essentially at ground surface while on the north (Annacis Island) side they are encountered at a depth of 80–85 m overlain by sequences of weak deltaic and alluvial materials. This paper describes the geotechnical investigation for the bridge and describes the design of six foundations including those for the two main piers. The north main pier is founded on unusually deep pipe piles about 85 m long. Key words: bridge, case history, earthquake, geological investigations, liquefaction, negative skin friction, pile, settlement analysis, site investigation.