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 (V_S-SPT) models and shear wave velocity-piezocone penetration test (V_S-CPTU) models developed in the literature and evaluates their transformation variabilities based on V_S-SPT-CPTU datasets collected from thirteen alluvium sites in the Taipei Basin, Taiwan. These data show that V_S is strongly correlated with the depth of soil (D) whereas it is weakly correlated with SPT-N or CPT-q_c, 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, V_S-SPT and V_S-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 V_S prediction. Finally, the application of these re-characterized models on V_S30 prediction is demonstrated with a practical example.