Coupled peridynamics modeling of liquefaction-induced shear strain localization and delayed failure

Liquefaction-induced shear strain localization and delayed failure occur when a low permeability overlying soil layer impedes the dissipation of excess pore water pressure generated by the underlying sand. When this phenomenon is simulated by classical finite element method (FEM), the predicted strain localization and lateral deformation are mesh-size dependent. In this study, the nonlocal peridynamics theory is introduced as a novel regularization technique for modeling such phenomenon. The computational model is based on coupling the non-ordinary state-based peridynamics (NOSBPD) and FEM for the solid and pore fluid phases, respectively. The liquefiable sand is modelled using a plastic model for large post-liquefaction shear deformation of sand (CycLiq) in the NOSBPD layer and the fluid flow is solved in the FEM layer. After validation of the proposed method via a VELACS centrifuge model test, the seismic response of an idealized one-dimensional sloping site with a low-permeability interlayer is analyzed using various discretization resolutions. The results show that the proposed method for liquefaction-induced strain localization analysis is insensitive to spatial discretization density. Finally, the Lower San Fernando dam failure case is revisited. The localized sliding and delayed failure of the dam observed in the field is achieved in the simulation. The results demonstrate the potential of the proposed method in assessing realistic cases associated with liquefaction-induced shear strain localization.