Development and evaluation of correlations between shear wave velocity and piezocone penetration test results on sand–silt mixtures

A detailed characterization of the shear wave velocity ( V s ) profile is essential for assessing the dynamic behavior and seismic design of geotechnical structures. A database of seismic piezocone test (SCPTU) results was compiled to develop empirical correlations for predicting V s of floodplain deposits with sand–silt mixtures at Jiangsu, China. Existing cone penetration test (CPT)– V s correlations for general soils proved inaccurate due to poor compatibility between the soil types and site-specific characteristics. In this study, new correlations were developed using SCPTU-derived parameters and evaluated through multiple performance indices including coefficient of determination, residuals, ratio, relative error, root mean square error, ranking index, ranking distance, and variable coefficient. The results indicated that the coefficient of correlation is highest for the combination of normalized cone tip resistance ( Q tn ) and soil behavior type index as per Jefferies and Davies ( I c, BJ ). Notably, the inclusion of the excess pore water pressure ratio ( B q ) in the I c, BJ formulation effectively captured partial drainage effects during CPT penetration. A newly built α-based criteria also gave consistent results with other performance indices. The proposed correlations were validated against V s values from SCPTU, conventional down-hole tests, and data from global sites such as New Zealand, confirming their reliability and applicability.