The Second Phase Construction of Kansai International Airport Considering the Large and Long-Term Settlement of the Clay Deposits

Kansai International Airport was planned to provide a fundamental solution to the aircraft noise pollution problem in the area surrounding Osaka International Airport (Itami Airport) and to the increasing demand for air transportation This man-made island was constructed 5 km offshore in Osaka bay to minimize noise pollution in residential areas. The airport commenced operations in September 1994. The second phase of construction work involved building an island further offshore than the island built in the first phase. Since the sea water is deep at the Kansai International Airport construction site and the layers below the seabed consist of a very soft layer of Holocene clay (immediately below the seabed surface) followed by alternate layers of Pleistocene clay and sand/gravel, the construction of an airport island was expected to produce a considerable amount of ground settlement. The amount of settlement during and after construction needed to be predicted in the design of the airport islands, and the results needed to be considered in the details of the land development work. This report outlines the second phase construction work at Kansai International Airport and describes the related geotechnical issues, with a particular emphasis on settlement.