Abstract: The liquefaction-induced diffusion and redistribution of the excess pore pressure in inhomogeneous strata may lead to pore water concentration in local areas beneath low permeability layers and cause shear strain localization and delayed failure. In this study, the nonlocal peridynamics (PD) theory is introduced as a novel regularization technique to model this phenomenon, overcoming the mesh-size dependency problem associated with the classical finite element method (FEM). The computational model couples PD and FEM for the solid and pore fluid phases, respectively. Liquefiable sand is modelled using a unified plastic model for large post-liquefaction shear deformation of sand (CycLiq). After validating the proposed method, the seismic response of an idealized one-dimensional sloping site with a low-permeability interlayer is analyzed using various discretization resolutions. It is demonstrated that the proposed method for liquefaction-induced strain localization analysis is insensitive to spatial discretization theoretically and numerically. At the same time, the parametric study shows that a higher location and a smaller permeability coefficient of the interlayer could lead to a greater lateral displacement of the stratum induced by shear strain localization.

Key words: liquefaction, earthquakes, shear strain localization, delayed failure, peridynamics