Effect of Cone Penetration Conditioning on Random Field Model Parameters and Impact of Spatial Variability on Liquefaction-Induced Differential Settlements

Abstract

The prediction of liquefaction-induced damage to structures can be aided in part by an understanding of the magnitude of inherent spatial variability of the underlying liquefaction-susceptible soils. However, little is known about the role of clean sand and overburden stress correction of the cone penetration resistance on the magnitudes of the random field model (RFM) parameters commonly used to describe spatial variability. Using the results of an extensive investigation of a level ground-level stratum test site with liquefaction-susceptible sand and silty sand, clean sand and overburden stress correction was shown to produce little impact to the autocorrelation length of the sands and silty sands investigated in this study. However, the inherent variability and depth-dependent trends in the corrected cone tip resistance are significantly impacted by conditioning commonly required for liquefaction analyses. The RFM parameters developed in this study were used to generate a calibrated, kriged volume of the test site and used to illustrate the roles of the intensity of shaking, the governing scale of a structure, and the spatial variability in the magnitude of liquefaction-induced differential settlement and angular distortion. Owing to the preferential liquefaction of looser materials before denser materials, it is shown that the lower intensities of shaking can produce larger differential settlements and poorer structural performance than higher levels of shaking in level-ground level-stratum sites. This work points to the continued need to study the role of spatial variability on the performance of structures in liquefaction-susceptible soils.