抄録
Due to the 2011 off the Pacific Coast of Tohoku of March 11, 2011, a large scale tsunami hit the Pacific coast area of the Tohoku and North-Kanto Regions, Japan. As a result of the earthquake and subsequent tsunami, approximately 900,000 tons of the tsunami-related deposits were left in the flooded area in Kesennuma city, Miyagi Prefecture. Since they were expected to be certainly recycled as embankment or backfilling materials in the prospective restoration and reconstruction works, proper treatment and management were essentially required for the tsunami-related deposits. Additionally, rapid completion of the treatment project was also important for the local residents to preserve living environment and improving public health. Thorough our laboratory experiments and a field demonstration to select soil modification materials for the tsunami-related deposits, both gypsum-based and lime-based materials were effectively accelerating dry sieving process. A part of the tsunami-related deposits contained naturally occurring heavy metals and required an additional treatment for immobilization. Elution concentration of arsenic and fluorine could be controlled stably below their criteria by using magnesia-based material. This paper summarizes the outline of the treatment of tsunami-related deposits and describes the geotechnical properties of recycled geomaterials in Kesennuma treatment area.
