Liquefaction Evaluation for an Interbedded Soil Deposit: St. Teresa's School, Christchurch, New Zealand

Liquefaction vulnerability indices (LVIs) are computed for an interbedded soil site at St. Teresa's School, Christchurch, New Zealand, to evaluate how various factors may have contributed to the standard LVI computations overestimating the potential for liquefaction damages during the 2010–2011 Canterbury earthquake sequence. The observed performance of the St. Teresa School site and its subsurface conditions are reviewed. An inverse filtering procedure is used to correct the cone penetration test (CPT) data for thin-layer and transition zone effects. LVI indices are computed using the CPT data from the site for a range of assumptions, including common default practices, site-specific fines content calibrations, inverse filtering of the CPT data, uncertainty in the triggering correlation, uncertainties in the correlations for shear and volumetric strains, and partial saturation. Other sources of potential conservatism in the LVI evaluations are discussed, including the potential contributions of the surface crust layer, dynamic response, and excess pore water pressure diffusion.