Applicability of existing CPT-Vs correlations to direct-push crosshole and cone penetration test data for shallow Holocene-aged New Zealand soil deposits

Abstract

A number of empirical correlations have been proposed to estimate shear wave velocity (Vs) using cone penetration test (CPT) data as a result of the growing availability of global databases. The performance of four existing CPT-Vs correlations in New Zealand conditions were assessed using a database of nearly 2000 CPT-Vs data pairs compiled from 52 co-located CPT and direct push crosshole (DPCH) sites across four regions in New Zealand. Differing trends of over- and under-prediction of Vs were evident across the different characteristics of the regional databases. In general, greater underestimates were evident for low cone tip resistance and sleeve friction values, while more reasonable estimates or slight overestimates were provided at higher values of these parameters. Across all considered correlations, the Christchurch-specific correlation based on a sCPT database generally underestimated Vs, with significant underestimates at depths less than 4 m for majority of the considered regions, representative of the effect of different Vs measurement methods. All these results demonstrate the influence of regional geological characteristics and Vs measurement method, highlighting the potential for the development of new empirical correlations.