There is a big project to construct New Kansai International Airport by reclaimed land at sea off Sensyu in Osaka Bay. Soil explorations and soil tests were perfoprmed to investigate engineering properties of marine clays of this area. The strata of this area consist of very soft alluvial clay and diluvial clays which continue more than 400 meters in depth. It is predicted that the stresses within the strata by the reclamated
fill are more than the estimated preconsolidation stresses not only in the alluvium but also in the diluvium. Therefore it is necessary to investigate the soil properties of deep strata.
　Special laboratory soil tests were carried out for undisturbed soil samples. This paper presents the results of physical tests, high pressure consolidation tests, long term consolidation tests, permeability tests and laboratory vane shear tests.