Abstract
The New Waste Disposal Area in Tokyo Bay is the last place available in the region where the wastes including municipal/industrial wastes, construction waste soil, dredged soil and others can be disposed. This disposal area is required to be available for a long period. A work for bulk compression of disposed clayey soils was carried out with the vacuum consolidation method at the block C of the area to prolong its service life. In this project, the prefabricated vertical drains (PVD) with a width of 150 mm and a thickness of 3.9 mm were used. The PVD were installed in a square placement of 1.8 m to the clay layers of +1.5 to -33.8 m in average elevations, to which the vacuum pressure of -65 kN/m2 was applied for 310 days. After a trial execution in 2005, full-scale work started in 2007 and ended in 2015. The vacuum consolidation method was applied to the area of 383,000 m2 and the average consolidation settlement observed was 5.13 m. As a result, the estimated amount of bulk compression attains a value of 2,167,000 m3 which corresponds approximately to the amount of soils dredged in Tokyo Bay for 2.3 years. This paper describes the general overview of this project in terms of geotechnical engineering.
