Model uncertainties of SPT, CPT, and VS-based simplified methods for soil liquefaction assessment

Abstract

Simpli ed methods for assessing soil liquefaction potential based on the standard penetration test (SPT) are prevalent in practice and widely accepted by several seismic design codes. When encountering sites that have not been investigated using SPT, such as offshore sites or sites with a high level of gravel content, engineers can only substitute the methods based on piezocone penetration test data (CPT-q c methods) or shear wave velocity measurements (V S -based methods); however, these two approaches perform inconsistently with methods based on SPT data (SPT-N methods). As a result, this paper exploits the datasets consisting of SPT, CPTU, and in-situ seismic test measurements from 13 alluvium sites in the Taipei Basin to compare the performance of prevalent SPT-N, CPT-q c , and V S -based methods. The discrepancies (uncertainties) of these methods are characterized as Gaussian distribution models, which is believed to be a feasible strategy for predicting equivalent results for SPT-N methods when SPT data are not available. Finally, the application of the proposed models to liquefaction potential index evaluation is demonstrated using a real case study.

Assessment of Liquefaction Potential by Comparing Semi-Empirical Methods Based on the CPT Test

“…Consequently, it is less reliable than the other two approaches. What's more, Olsen's method includes an Rf term that regularizes the CRR curve, and hence the safety coefficient, giving us results that don't correspond to practice [21][22][23]. The adjusted qc1N values determined by the Juang [7] and Robertson [9], [20] approaches are virtually identical, but there is disagreement for the qc1N,cs values (Figures 12 and 13).…”