Abstract
The new waste disposal site is the last place left in Tokyo bay which can dispose of municipal/industrial wastes, construction waste soil, dredged soil and so on carried from the Tokyos 23 wards. Therefore, a life-prolongation project for utilizing this area for a long period is on going from 2005 to the present. Its purpose is to increase a capacity of the disposal area by reducing the volume of disposed dredged soil by using the vacuum consolidation method. In this project, there were two geo-technical features. One was a necessity to evaluate the settlement considering the influence of the intermediate sand layers widely existing in a clayey layer. The other was a necessity to determine the vacuum consolidation period with ensuring the average consolidation degree of over 80% based on a comparison of the actual settlement with the predicted one. This paper describes about management methods of consolidation settlement, an intermediate sand layers distribution, the settlement properties and the volume reduction effect of clayey soil by using the vacuum consolidation method.
