The Mission Bridge, built in 1973, spans the Fraser River in British Columbia and is a critical link in the Province’s disaster recovery network. The four-lane bridge is 1,050 m long and is supported by a series of concrete bents or piers founded on piles. The approach piers are supported on short timber piles and the river and riverbank piers are supported on long steel H-piles. The bridge site is underlain by potentially liquefiable Fraser River sand and liquefaction is the key issue affecting the seismic performance of the bridge. Seismic soil-structure and deformation analyses were conducted to evaluate and design seismic retrofit
measures to minimize the effects of liquefaction induced displacements. The retrofit measures included ground remediation schemes at the two abutments, the two river banks piers, and the approach piers. Ground remediation used various techniques, including vibro-replacement, compaction piles, compaction grouting, seismic drains, and toe berms. This paper describes the seismic retrofit strategy, geotechnical retrofit construction and some key challenges faced during the design and construction.
Thavaraj, T., A. Sy and B. Hamersley. 2018. “Geotechnical Seismic Retrofit of Mission Bridge, British Columbia, Canada.” in Proceedings of GeoEdmonton, Transportation Geotechnique – Moving Forward, 71st Canadian Geotechnical Conference and the 13th Joint CGS/IAH-CNC Groundwater Conference, Edmonton, Alberta, 24-26 September 2018. Edmonton, AB: Canadian Geotechnical Society.