Empirical formulas for shear wave velocity prediction and their uncertainties: a case study of thirteen alluvium test sites in the Taipei Basin

This paper examines the performance of shear wave velocity-standard penetration test (VS-SPT) models and shear wave velocity-piezocone penetration test (VS-CPTU) models developed in the literature and evaluates their transformation variabilities based on VS-SPT-CPTU datasets collected from thirteen alluvium sites in the Taipei Basin, Taiwan. These data show that VS is strongly correlated with the depth of soil (D) whereas it is weakly correlated with SPT-N or CPT-qc, which indicates that most of the transformation models in the literature are unsuitable to these sites since they are usually formulated without soil depth. Thus, VS-SPT and VS-CPTU empirical formulas and their transformation uncertainties for these sites in the Taipei Basin are re-calibrated in this paper, and they perform more unbiased with lower variability as shown in this paper, which indicates they provide a suitable approach to those sites for VS prediction. Finally, the application of these re-characterized models on VS30 prediction is demonstrated with a practical example.