Comparison of the Shear Wave Velocity Prediction Models Derived from SPT and CPTU, A Case Study from Lingding Ocean
摘要
Shear wave velocity (Vs) is a key parameter for evaluating the dynamic properties of soils and seismic site response. This study develops site-specific Vs correlations for the Lingding Ocean using in-situ data from six boreholes along the Hong Kong–Zhuhai–Macao Bridge alignment. The site consists of Quaternary marine and continental deposits overlying weathered granite and metamorphic rocks. A database of 445 H-Vs pairs, 108 SPT N-Vs pairs (0–40 m) and 240 CPTU-Vs pairs (0–55 m) was compiled. Ordinary least-squares regression was used to derive correlation between Vs and depth, SPT N-values and CPTU parameters (qc, qt and qtfs). Model performance was assessed using R², RMSE, MAPE, an accuracy ratio within a 20% error band and residual analysis. The H-Vs correlation shows limited predictive capability (R² = 0.43). Among the in-situ models, the SPT-based N-Vs correlation provides the lowest RMSE, and comparison with several widely used all-soil N-Vs relations from the literature shows that the proposed N-Vs correlation yields less biased and more consistent estimates for the Lingding Ocean sediments. The three CPTU-based correlations (qc-Vs, qt-Vs and qtfs-Vs) achieve higher R². Residual analysis indicates that all in-situ correlations are essentially unbiased, and the calibrated SPT-Vs and CPTU-Vs correlations therefore provide practical tools for estimating Vs profiles at this and similar marine sites.