TEMPORAL VARIATION OF SEDIMENTARY STRUCTURE OF DREDGED SOIL LAYER IN AN ARTIFICIAL INTERTIDAL FLAT: FOLLOW UP RESEARCH USING MASW AND ITS VERIFICATION

Abstract

 Dredged soils from navigation channel or anchorage area have been used in construction of artificial intertidal flat in various regions in Japan. Temporal variation of the dredged soils confined in the intertidal flat, however, has not been clarified yet. In this study, follow up research at an artificial intertidal flat in the Tokuyama-Kudamatsu Port, Yamaguchi, Japan, was conducted for several years after the construction in 2008. Shear wave velocity of only 25 m/s was obtained by MASW in the extremely soft sediments, and this value was verified by a seismic cone test. The gradual increase in shear strength with elapsed time was caused by not only decrease of water content (decrease of void ratio, i.e., densification) in association with consolidation but also chemical bonding in association with thixotropy.