Liquefaction-Induced Damage and CPT Characterization of the Reclamations at CentrePort, Wellington

The 2016 M-w 7.8 Kaikoura earthquake caused widespread liquefaction and significant ground movements in thick end-dumped gravelly fills and hydraulically placed dredged sandy fills at CentrePort, Wellington. Settlement of 200-300 mm occurred throughout the reclamation, and settlement as large as 400-600 mm occurred near the reclamation edges where lateral movements on the order of 0.5-1.5 m occurred, which in turn damaged wharves and structures. Ground motions and damages at the port produced by the 2013 M-w 6.6 Cook Strait and the 2013 M-w 6.6 Lake Grassmere earthquakes are compared with those caused by the 2016 M-w 7.8 Kaikoura earthquake. The documentation of liquefaction manifestations and surveys of ground movements followed by comprehensive subsurface investigations performed after the Kaikoura earthquake characterized the different fill materials at the port and the underlying marine sediments and Wellington Alluvium layers, as well as key aspects of the port's seismic performance. The cone penetration test data together with the grain-size composition of the fills indicate the finer sand-silt fractions of the well-graded gravelly fill had a critical influence on the liquefaction resistance and performance of the gravelly fill during the Kaikoura earthquake. Key insights are shared through examination of this case history involving the liquefaction of gravelly soils.