Nonlinear Site Response Analysis with Pore-Water Pressure Generation for Liquefaction Triggering Evaluation

The cyclic-stress approach is widely used to evaluate level-ground liquefaction triggering. Although easy to use, several limitations introduce significant uncertainty in the analysis, including: (1) several correction factors are required, including the depth reduction, magnitude scaling, and overburden correction factors; (2) seismic demand is quantified using a total-stress framework to capture an effective stress phenomenon [pore-water pressure (PWP) generation and liquefaction]; and (3) because it is based on surface manifestations, its applicability outside of database parameters (e.g., depths>10 m) is unknown. In this study, the authors performed a broad parametric study to assess the viability of using nonlinear site response analysis with validated constitutive and PWP generation models to evaluate level-ground liquefaction. For a wide range of conditions, the parametric results agreed with published empirical liquefaction-triggering relations. The nonlinear site response analysis with PWP generation also correctly predicted liquefaction for dynamic centrifuge tests and field cases, demonstrating that this approach can assess level-ground liquefaction while avoiding highly uncertain correction factors required in the cyclic stress method.