Influence of Permeability on Liquefaction-Induced Shear Deformation

Abstract

Permeability of a liquefiable soil profile may affect the rate of pore-pressure buildup and subsequent dissipation during and after earthquake excitation. Consequently, effective soil confinement and available resistance to shear deformations may be significantly dependent on permeability in many practical situations. If present, spatial variation in permeability may even have a more profound impact on available overall shear resistance. Indeed, case histories and experimental evidence (shake table and centrifuge tests) suggest that spatial permeability variation in stratified liquefiable deposits can highly influence the nature and extent of associated lateral deformation. In such situations, the onset of liquefaction-induced densification may result in water or water-rich thin interlayers trapped below overlying low-permeability strata. The presence of these low-shear-strength interlayers may trigger excessive (or even unbounded) localized shear deformations (flow failure mechanism). In this paper, numerical modeling is employed in order to investigate the influence of permeability and the spatial variation thereof on liquefaction-induced shear deformations. The involved response characteristics are numerically simulated using a fully coupled two-phase (solid–fluid) Finite Element program.