The consolidation characteristics interpreted with the isotache concept have been studied by many researchers, including the Port and Airport Research Institute. The aim of most of these studies has been to calculate secondary consolidation with high accuracy in order to evaluate the long-term settlement of large-scale structures. In a previous study of the first author and his co-workers, the long-term consolidation characteristics of Osaka Bay clays, collected from the construction site of the Kansai International Airport, were examined, and a simplified method based on the isotache concept, using a compression curve and the relationship between the consolidation yield stress (preconsolidation pressure) and the strain rate, was proposed. The former and the latter were obtained from constant rate of strain consolidation (CRS) tests and long-term consolidation (LT) tests, respectively.
The latter is expressed by an equation with three isotache parameters. It is noteworthy that the three isotache parameters can be commonly determined for the Osaka Bay clays retrieved from various depths up to 300m below the seabed. In the present study, the proposed method was applied to worldwide clays with various characteristics using the common values for the isotache parameters determined for the Osaka Bay clays. It was found that the long-term consolidation behavior of those worldwide clays can be well characterized by the proposed method, along with the common values for the isotache parameters.