The Plastic board drain (PD) method for self-weight consolidation has been proposed by the authors as one of soil improvement methods in reclamation works using high water content dredged soils. This method is the vertical drain method for accelerating self-weight consolidation using a PD and floating driving machine to consolidate such very soft grounds in a short period. The effectiveness of the PD for self-weight and loading consolidation was confirmed by laboratory tests using a large size cylindrical container (H=210cm, D=30cm) filled with dredged clay slurry of high water content (w=1000%).
In recent years, for maintenance of navigational channels or purification of the environment, it is often planned to dredge the clayey deposits on the surface of sea, and utilize the dredged spoils as landfill and man-made island materials. Typically, the dredged spoils are temporarily stored in a nearby sedimentation pond and then very soft ground is formed. Nevertheless, since an artificial ground filled with the spoils has a very high water content such as 200 to 300%, it is necessary to consolidate it properly for the utilization of landfill and man-made island. Kamon et a1.(1991), Shinsha et. al. (1991) and Yoshikuni et.al. (1994,1995) have studied the vertical drain method using plastic board and horizontal drain method as one of the soil improvement methods in reclamation works for dredged clay. Therefore, the authors have developed the vertical drain method for accelerating self-weight consolidation using plastic board drains as a method of consolidate such very soft grounds in a short period. This method is not only possible to pour the large quantity dredged soils into the landfill pond but also is possible to utilize a landfill ground as soon as possible after the end of reclamation.
