ABSTRACT
Widespread liquefaction occurred in the reclamations at CentrePort, Wellington (New Zealand) during the 2016 Kaikōura earthquake (Mw 7.8) which produced a relatively moderate seismic demand (peak horizontal ground acceleration of 0.2-0.3g at the site). Most of the damage occurred in the end-dumped fills (i.e., the Thorndon reclamation) which are comprised of 60-80% gravels and 20-40% sand-silt mixtures. This study presents results from CPT-based liquefaction assessment on a representative profile from the Thorndon reclamation using both a semi-empirical simplified method and advanced dynamic effective stress analysis. The simplified assessment results are generally consistent with observations since the CPT is able to capture the response of the finer sand-silt fraction in the matrix, which likely controlled the liquefaction behavior during the Kaikōura earthquake. The preliminary effective stress analysis provides insights on the timing and onset of liquefaction, and processes involving dynamic interactions within the deposit, thus illustrating important response characteristics which are beyond the capability of simplified methods. This paper illustrates the use of the CPT in performing conventional simplified and dynamic liquefaction analysis when applied to non-conventional or problematic soils for the assessment with reference to a well-documented case study.
