Abstract
Hakuryuko soft ground is located in the northeast end of Yonezawa Basin consisting of alternated layers of organic soft cohesive soils more than a depth 100 m. The expressway construction was planned over this soft ground by the using vacuum consolidation as a ground improvement method. The ground surface is a plow layer following by a fibrous peat and the alternating layers of organic and cohesive soils. A sand layer existing between the organic and cohesive soil layers is considered to reduce the effectiveness of vacuum consolidation. Therefore, full-scale trial embankments were placed to verify the effectiveness of vacuum consolidation. As the result, the vacuum consolidation method was found to be applicable to this kind of soft ground when using with the auxiliary construction method to improve the surface airtightness.
