Liquefaction Potential and Sediment Ejecta Manifestation of Thinly Interbedded Sands and Fine-Grained Soils: Palinurus Road Site in Christchurch Subjected to 2010–2011 Canterbury Earthquake Sequence

Abstract

The effect of spatial variability on the liquefaction prediction and liquefaction-induced ground failure of a soil profile with thinly interbedded layer of sand and clay was examined using simplified procedures and fully coupled two-dimensional (2D) nonlinear dynamic analysis (NDA). The Palinurus Road site in Christchurch, New Zealand, subjected to the 2010 Darfield and 2011 Christchurch events, was selected for the analyses. The liquefaction vulnerability of the site was estimated using one-dimensional (1D) liquefaction vulnerability indices (LVIs), and the results were compared with the results of NDAs and field observations. Spatially correlated random fields conditioned on corrected cone penetration tests (CPTs) were generated based on sand-like and claylike portions of the interbedded soil profile. CPT data were corrected for the thin-layer and transition zone effects. The generated random fields were assigned to the interbedded layer of the stochastic model to examine the effect of spatial variability on the system dynamic response, cross-interaction between layers, and liquefaction-induced diffusion during the evolution of liquefaction and postliquefaction. The potential of sediment ejecta manifestation using the artesian flow potential (AFP) and ejecta potential index (EPI) also was investigated for the stochastic models and compared with those of deterministic models. This study demonstrates the value of advanced 2D NDA modeling with realistic soil spatial variability for understanding inconsistent ejecta predictions from simplified tools. The approach can guide future refinements to assessment procedures and provide insights into key factors controlling manifestation in complex stratified sites.