Evaluation of Two Numerical Modeling Approaches for Liquefaction Investigation of Fines-Dominated Soils in Wildlife Liquefaction Array (WLA) Case Study

Soil liquefaction evaluation is critically important in site seismic analyses. The presence of fines-dominated materials such as clayey and silty soils has been reported in many of the occurred liquefaction cases. Despite this observed fact, there are limited studies analyzing the presence of such materials in liquified sites compared to sandy sites. One of the practical methods to analyze such sites is to use Finn-Byrne formulation for pore water pressure buildup calculation along with other constitutive models such as simple Mohr-Coulomb. Recent advancements in constitutive models with more sophisticated PM4Silt and PM4Sand models allowed a more rigorous liquefaction analysis of such sites. In this study, these two modeling approaches are applied to Wildlife Liquefaction Array (WLA) monitored site. The WLA site profile consists of about 2.5 m of surface silty soil, 4.5 m of silty sand, followed by 5 m of silty clay, and a thick silty layer at the bottom. The liquefaction analyses of the WLA site under the 1987 Superstition Hills earthquake were conducted using these two approaches and compared to observed liquefaction. The results of the study showed that both approaches, despite significant differences in their theory and input parameters, have the capacity of predicting excess pore water pressure (EPWP) generation in the non-plastic silty layers. However, the PM4Silt model was able to produce a better prediction of EPWP variations in the low-plasticity, non-liquefiable deep silty layer during the earthquake.