SPT–CPTU Correlations and Liquefaction Evaluation for the Island and Tunnel Project of the Hong Kong–Zhuhai–Macao Bridge

Abstract

Considering the importance and complexity of the island and tunnel project for the Hong Kong–Zhuhai–Macao Bridge (HZMB), simple piezocone penetration (CPTU) testing has difficulties evaluating soil mechanics and characteristics accurately. Since geotechnical engineers are more familiar with standard penetration tests (SPT) and related design procedures, there is a necessity for reliable SPT–CPTU correlation so that CPTU data can translate to SPT design. This paper reviews existing correlations in the literature between SPT and CPTU, which depend on grain size, fines content or the soil behavior-type index. Since geologic contexts have not been investigated in the existing correlations, a linear function with zero-intercept SPT–CPTU correlations has been developed for every engineering geological unit layer, and the correlations were applied in liquefaction potential evaluation in cases where there was a lack of SPT data. For verification, this liquefaction evaluation was also carried out using both CPTU and SPT testing, and site-specific qt/N ratios of 0.11, 0.16, 0.30 and 0.41 for different soil categories are presented. The developed SPT–CPTU correlations are in accordance with existing correlations in the literature, and the results also reveal that the developed correlations and the liquefaction evaluations are essential for site investigation and geotechnical design in the HZMB area, especially providing a reference for similar engineering surveys.