Abstract
In order to prevent a diffusion of fluid mud over the seabed with a possibility which contaminents may be included, a containing work has been carried out by covering the area wtih cement treated soils. According to the field investigation result, the mean wet density of the fluid mud was 1.05g/cm3 and its maximum layer thickness was 10mm. For a purpose to find out an optimal execution plan for containing the fluid mud, preliminary laboratory underwater casting test was carried out using several tens types of cement mixed soils. As a result, it was observed that the treated soil A of the density of 1.1g/cm3 with low flowability, cast as first layer with thickness of 10cm, created big voids by itself, in which the fluid mud was contained, and the treated soil B of the density of 1.3g/cm3 with high flowability, cast as second layer with thickness of 10cm, effectively formed the covering layer over the first layer. The laboratory test demonstrated that the fluid mud could be effectively contained into the cement treated soils by using the treated soils A and B. In addition, a field trial test was carried out, which demonstrated that the fluid mud could be effectively contained into the treated soils without diffusion by the abovementioned staged casting of the treated soils A and B.
