Spatial Variability of CPT Parameters and Silty Fines in Liquefiable Beach Sands

Increasing awareness of the role of spatial variability in the assessment of liquefaction susceptibility has driven the need to characterize the vertical and horizontal spatial variability of liquefiable soils. Specifically, the variability of the standard penetration tests and cone penetration tests (CPTs) and the fines content are needed to evaluate liquefaction triggering. Although the analysis and determination of the vertical inherent variability of sandy soils has been conducted in several prior studies, very little prior work has been conducted to characterize the typical horizontal component of spatial variability. This study employs a comprehensive data set developed from a test site established to evaluate liquefaction susceptibility and mitigation to characterize the vertical and horizontal spatial variability in CPT cone tip and sleeve resistance and the fines content. Random field model (RFM) parameters, such as the vertical and horizontal scale of fluctuation, coefficient of inherent variability, and trend functions for each measurement are established as well as the variability in these parameters. A site-specific CPT-based fines content correlation is employed within kriging simulations performed using calibrated geostatistical models and demonstrated the effect of the assumed variogram model on the accuracy of fines content measured in separate independent boreholes. This paper shows that calibrated kriging simulations can sufficiently predict the fines content in silty beach sands and that the spatial variability of fines content can be estimated using RFM parameters developed from CPTs. (C) 2017 American Society of Civil Engineers.