Interactive behavior of Pleistocene marine foundation of existing 1st phase island due to construction of 2nd phase island of Kansai International Airport

Abstract

A series of elasto-viscoplastic finite element analyses is performed to assess the interactive behavior of the Pleistocene marine foundation of the existing 1st phase island due to the construction of the adjacent 2nd phase island of the Kansai International Airport in Osaka Bay. Marine foundations modeled independently for the 1st and 2nd phase islands, considering the increase in thickness of the individual layers toward the offshore area, are proposed for the finite element analyses. The mechanism for the propagation of excess pore water pressure, due to the construction of the adjacent reclamation, is discussed through a numerical procedure using the concept of "mass permeability" introduced to model the actual process of the dissipation of excess pore water pressure in the field. A modeling of the compressibility of the quasioverconsolidated Pleistocene clay is also adopted to analyze the long-term settlement behavior. It is found that the present numerical analyses are capable of describing the large and long-term settlement together with the insufficient dissipation and propagation of excess pore water pressure due to the construction of the adjacent reclamation in the Pleistocene clay and sand gravel layers that has actually taken place in the field. The calculated performance is validated by comparing it with the measured results obtained for over 20 years from the start of the construction.