The Ryukyu limestone formation is not assumed to be a suitable load bearing foundation in Ryukyu Archipelago. The characteristics of Ryukyu limestone with various porosity under static and dynamic conditions have been investigated by the authors. Furthermore, the behavior of the interface between piles and Ryukyu limestone are tested using large-scale dynamic shear testing device. Some model piles founded on Ryukyu limestone are subjected to static and dynamic loads to check their deformation response and their load-bearing capacity. The authors will explain fundamental studies on foundations on Ryukyu Limestone Formation under static and dynamic loading conditions and present the outcomes of these studies and discuss their implications on bridge piles.
Ryukyu limestone formation, which is broadly divided into coral limestone and sandy limestone, is widely distributed in Ryukyu Archipelago. As limestone is solvable due to percolating groundwater and accumulation of corals and as well broken pieces, the porosity of limestone is large. Furthermore, they may contain some large scale cavities due to combined action of groundwater and tectonic movements. Therefore, the Ryukyu limestone formation is considered to be not suitable as a foundation rock for large-scale engineering structures. When the thickness of the Ryukyu limestone formation is quite thick, it results in the non-economical foundation design. This is a serious engineering issue in Okinawa Prefecture, Japan and some fundamental studies are necessary to clarify whether it is really unsuitable or suitable as foundation rock. The authors investigate the characteristics of Ryukyu limestone with various porosity under static and dynamic conditions. The behavior of the interface between piles and Ryukyu limestone are tested using large-scale dynamic shear testing device. Furthermore, some model piles founded on Ryukyu limestone were subjected to static and dynamic loads to check their deformation response and their load-bearing capacity. In addition some analytical and numerical studies are proposed. The authors explain these fundamental studies on foundations on Ryukyu Limestone Formation under static and dynamic loading conditions and present the outcomes of these experimental studies and discuss their implications in foundation design.
