CPT-Based Random Field Model Parameters for Liquefiable Silty Sands

摘要

Although soil is not deposited as a result of random processes, it is often convenient to treat the inherent variability within a given soil unit as a random field. Some reliability-based design codes require the adjustment of resistance factors within the LRFD framework based on site variability; however, there is a general lack of familiarity with methods to determine and model the inherent spatial variability of soil stratigraphy. Thus, random field model parameters that have been reported in the literature are often used instead of those developed from site-specific in-situ data. Studies of well-documented sites can help to improve the range in random field model parameters appropriate for various soils. In this study, the inherent variability of a liquefiable, silty sand soil present at a test site developed to evaluate liquefaction mitigation methods is characterized. Random field geostatistical model parameters were estimated for the corrected cone penetration resistance and sleeve friction resulting from the cone penetration tests (CPTs). Stationarity of individual soil layers was achieved using linear trend removal. The coefficient of inherent variability and scale of fluctuation determined using fitted autocorrelation models and differences between the model parameters is described. The random field model parameters presented herein provides a comprehensive set of parameters for modeling the spatial variability of potentially liquefiable silty sands.