SOFT CLAY IMPROVEMENT TECHNIQUE BY DEWATERING AND MIXING SANDY SOIL

Treatment of soft clay is one of the problems in geotechnical engineering. A soil dredged from a pond is very soft because of high water content and possessing organic content. The soft soil is expected to be utilized as a geo-material. The purpose of this study is to investigate a cheaper, easier and environmentally friendly method in comparison with the conventional soil improvement methods for improving soft clay with low bearing capacity, low shear strength and excessive settlement. The proposed dewatering method was adopted to the soft clay collected from a pond in Kumamoto Prefecture, Japan. The functionality of this proposed method is thus, by inserting a geosynthetic material in the soft clay for dewatering and evaporation of excess water without energy. This is an effective, economical and low environmental impact method for dewatering because it does not require other resources such as chemicals using hardening agent or mechanical devices for dehydration with high pressure. In the experiment, it was found that Kumamoto clay with an initial water content of 1.5 times the liquid limit can be reduced to less than the liquid limit within a week by the proposed method. In addition to dewatering, sandy soil was mixed with the clay and cone penetration test was carried out. The effective mixing content of sandy soil for obtaining the target cone index was also evaluated.