Numerical simulation of liquefaction phenomenon considering infinite boundary

Abstract

The response of liquefaction behaviour can be analyzed by incorporating the effects of the transient flow of the pore-fluid through the voids, which requires a two-phase continuum formulation for saturated porous media named ‘mixture theory’. The saturated soil system is modelled as a two-phase material based on the Biot's theory for porous media. Infinite elements have been incorporated in the solution algorithms to simulate infinite boundary. A computer code is developed in FORTRAN 90 considering fully coupled dynamic analysis to determine the responses of pore fluid and soil skeleton of an unbounded saturated sandy layer. The unconditionally stable generalized Newmark-Beta method is employed in the solution algorithm for evaluation of response at each time step. A generalized non-associative plasticity-bounding surface model Pastor–Zienkiewicz Mark III is considered to describe the inelastic behaviour of soils under earthquake loading. A parametric study is conducted to consider the effect of the material nonlinearity of the soil grain on liquefaction behaviour. A significant reduction in displacement and excess pore pressure is observed while considering unbounded domain. The salient feature of the solution algorithm is simulation of build up pore pressure and consequent reduction in mean effective stress. It was also observed that key parameters like permeability, earthquake intensity and shear modulus had significant effect on liquefaction response.