抄録
Dredged soils from navigation channel or anchorage area have been used in reclamation of artificial intertidal flats in Japan. Immediately after the reclamation, because the dredged clay filled in the intertidal flat has not consolidated, a safety assessment system is strongly required to avoid depression of foot into an extremely soft soil at a place where sand capping is significantly thin. In addition, temporal variation of the dredged soils filled in the intertidal flats has not been clarified yet. In this study, a follow up research at an artificial intertidal flat in Tokuyama-Kudamatsu Port, Yamaguchi, Japan, was periodically conducted for several years since its completion of reclamation in 2008. Shear wave velocity obtained by MASW in the extremely soft sediments was only 25 m/s. Gradual increase with elapsed time in shear strength of dredged soil layer was mostly caused by chemical bonding (thixotropy effect) rather than densification (consolidation). Because MASW can describe both the thickness of sand capping and softness of the dredged soils, this technology is useful to assess the safety of artificial intertidal flats.
