This paper has reviewed the soil sampling techniques for the ground of coastal areas, to comprehend the position of Japanese sampling technology on a global basis. It was also carried out to establish the appropriate testing procedures for the laboratory and the in-situ test to minimize the disturbance effect from soil sampling.
　In the meantime, the typical soil behaviors of Japanese clays which are difficult to explain with the conventional effective stress concepts such as soil cementation and aging effect, was attempted to be quantitatively investigated by the interactive approach of soil microstructures and Diatom Microfossils which is abundantly found in Japanese clayey soils.
　In addition, through the case studies on the four ground conditions such as intermediate soil, clay with finger coral, soils improved by sand compaction, and coal ash treated soil, their engineering characteristics and the applicability of unconfined compression test and in-situ test were investigated in this study.