2018 Volume 6 Issue 1 Pages 32-48
The New Waste Disposal Area is the final disposal site in Tokyo Port to dispose of the wastes such as municipal/industrial wastes, construction waste soil and dredged soil. Therefore, to utilize this area for a long time, measures for expanding its capacity or reducing the volume of wastes have been taken. The work for volume reduction of disposed clayey soils was carried out with the vacuum consolidation method at block C of the area to prolong its service life. In this project, the prefabricated vertical drains (PVDs) with a width of 150 mm and a thickness of 3.9 mm were used. The PVDs were installed in the clay layer at the average elevations of +1.5 to -33.8 m with a square spacing of 1.8 m with the negative pressure of 65kN/m2, which is equal to the consolidation pressure increment, was applied for 310 days.
The trial period began in 2005 and the main project period started in 2007 and was completed in 2015. During this period, work was performed on 383,000 m2; the mean settlement volume was 5.13 m and the volume obtained through settlement consolidation was 2,167,000 m3. This means that the service life of this disposal area was extended for 2.3 years. This paper provides the general overview of this project with a focus on geotechnical engineering.
