FEM-FDM COUPLED LIQUEFACTION ANALYSIS OF A POROUS SOIL USING AN ELASTOPLASTIC MODEL

The phenomenon of liquefaction is one of the most important subjects i n Earthquake Engineering and Coastal Engineering. In the present study , the governing equations of such coupling problems as soil skeleton a nd pore water are obtained through application of the two-phase mixtur e theory. Using a up (displacement of the solid phase-pore water press ure) formulation, a simple and practical numerical method for the liqu efaction analysis is formulated. The finite difference method (FDM) is used for the spatial discretization of the continuity equation to def ine the pore water pressure at the center of the element, while the fi nite element method (FEM) is used for the spatial discretization of th e equilibrium equation. FEM-FDM coupled analysis succeeds in reducing the degrees of freedom in the descretized equations. The accuracy of t he proposed numerical method is addressed through a comparison of the numerical results and the analytical solutions for the transient respo nse of saturated porous solids. An elasto-plastic constitutive model b ased on the non-linear kinematic hardening rule is formulated to descr ibe the stress-strain behavior of granular materials under cyclic load ing. Finally, the applicability of the proposed numerical method is ex amined. The following two numerical examples are analyzed in this stud y: (1) the behavior of seabed deposits under wave action, and (2) a nu merical simulation of shaking table test of coal fly ash deposit.