Improving soil liquefaction prediction through an extensive database and innovative ground motion characterization: A case study of Port Island liquefied site

Abstract

Liquefaction is a phenomenon in which soils lose their strength and stiffness significantly during earthquake shakings. It is very important to accurately predict the liquefaction triggering and permanent displacement of liquefied sites under different seismic conditions. This study systematically investigates the effect of ground motion characteristics on the evolution of important physical quantities during the liquefaction process, while the relative capacity of various ground motion intensity measures (IMs) in predicting the pore-pressure generation and the permanent deformation in liquefiable soils are studied. An extensive database containing 501 three-component ground motion records is established to improve soil liquefaction prediction under different earthquake scenarios. A significant number of fully nonlinear dynamic analyses are performed for the Port Island liquefied site, where advanced constitutive models are used to realistically characterize the nonlinear soil behaviors. Results from numerical simulations demonstrate that the energy-related IMs such as CAV5 have a superior predictive capacity than the peak ground acceleration in predicting the liquefaction initiation and permanent displacement, but the predictions based on scalar IMs are not sufficient because residuals are strongly depended on earthquake magnitude and rupture distance. On the other hand, vector IMs that incorporate both energy and peak value characteristics of ground motions can improve the predictive capabilities regarding pore pressure generation and permanent deformation in liquefiable soils. The study helps lay down the basis towards an improved procedure for liquefaction hazard evaluation and mitigation.