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The November 2016 M7.8 Kaikoura earthquake in New Zealand caused severe damage to infrastructure assets at CentrePort in Wellington, including the 585m length Thorndon Container Wharf constructed in the 1960s. Damage to this wharf was primarily due to liquefaction of the ground behind the wharf, and resulted in the complete structural failure of a substantial number of piles, especially those supporting the landward wheels of the STS container cranes. Raker pile failures resulted in the landward edge of the deck being displaced 0.2m higher than the seaward edge. The ground immediately behind the wharf deck settled up to 0.5m below deck level, and the wharf displaced seawards by up to 1m.
Following the earthquake all container vessels and operations were halted along the wharf, resulting in significant disruption to CentrePort’s business. Substantial temporary securing works were required to secure the container cranes, maintain support to the wharf structure and stabilise the reclamation behind the wharf. This was to enable container operations to recommence and to maintain business continuity.
Container handling operations were revised to accommodate the altered configuration of the secured wharf and temporary container terminal. With the earthquake damaged deck only being able to support container cranes, the cranes were required to load and unload using backreach operation only.
The temporary securing works included installing stone columns within the reclamation fill behind the wharf, underpinning the wharf to carry vertical loads from the container cranes, restraining the wharf against further lateral movement, and installation of land based mooring dolphins. Other seismic risk mitigation works were also undertaken. Health and safety of the construction workers was the key driver in adopting an innovative scheme to underpin the wharf. All works were designed and constructed over a nine month period to provide a temporary facility for container handling operations.