Abstract
A case record of design, construction and field observation of a quaywall on coral debris mixed soil is described. Matrix of the foundation soil is the calcareous intermediate soil, in which porous finger corals form a loose skeleton. Preliminary design of the quaywall by the total stress analysis with φu=0 condition, in accordance with the current design manual, indicated a necessity of extensive soil improvement. Considering a possibility of higher value of the in situ permeability due to the porous finger coral skeleton, the effective stress analysis was employed by tracing the change in distribution of the excess pore water pressure with time throughout the series of construction stages. Change in the design method has led a substantial reduction of construction cost.Results of field observation suggested that this particular design was a little too conservative. The governing factor to this overdesign seemed a possibility of far larger in situ permeability than that used in the design. An engineering question of how to cope with this kind of geotechnically difficult soil is discussed.
