PREDICTION METHOD ON DEFORMATION BEHAVIOR OF CAISSON-TYPE SEAWALLS COVERED WITH ARMORED EMBANKMENT ON MAN-MADE ISLANDS DURlNG EARTHQUAKES

MAMORU KANATANl, TADASHI KAWAli and HITOSHI TOCHIGl

ABSTRACT : In this paper, centrifuge shaking table tests were conducted in order to understand the performance of seawalls during a seismic event. The model tests showed that the displacement of the caisson was much affected by the seaward shear deformation of the sand seabed beneath it during shaking. It was also confirmed that an armored embankment played an important role in the displacement of the caisson during shaking. Based on these test results, a two-dimensional DEM-FEM coupled analysis method was newly developed to numerically predict the deformation of seawalls covered with armored embankments during earthquakes. The movements of the armor units were calculated by DE analysis and deformations of the caisson, rubble mound, sand seabed and backfill were calculated by FE analysis considering the non-linearity of the soil materials based on the effective stress. Dynamic interaction was taken into account by delivering the nodal displacements of the finite elements or the nodal forces converted from the contact forces through the imaginary distinct elements defined at the boundaries between the DE and FE domain. The applicability of this method to the prediction of the deformation of seawalls was verified through numerical simulations of the centrifuge model test.

Key words : centnfuge couplmg analys s distmct element method fimte element method seawall sersnnc deformation (IGC : D7/E8/E14)