Settlement of the soft landing moundless structure with piles in the Kumamoto port has recently
become a significant issue that cannot be ignored probably due to consolidation of a soft clay
widely and thickly deposited. Therefore, a height raising is being considered to maintain a
required performance as breakwater. To design the height raising, a ground investigation under the
structure is necessary. However, it is difficult or inappropriate to temporarily move the structures,
to drill the structures for the ground investigation or to perform it keeping a distance from the
structures because the results may not represent the mechanical properties of the ground under the
structures.
　In this study, the authors conducted a centrifuge model test and numerical analysis to evaluate a
horizontal resistance of the soft landing moundless structure with piles and its change due to
long-term consolidation. In the centrifuge model test, two identical models of the structure were
prepared in a single model ground, where one was laterally loaded right after a given centrifugal
force (50G) was applied and the other was also laterally loaded after a primary consolidation
ended under the centrifugal force (50G). In the numerical analysis, the horizontal resistance at
different consolidation degrees of the ground was investigated.

Key Words: soft landing mound-less structure with piles, consolidation settlement, horizontal resistance, centrifuge model test, numerical analysis*