There was a program in PBS/Discovery/TLC a few months ago about the Kansai airport. It is an excellent documentary (1 hour), with the various descriptions on the stages of construction, designs, and discussion about the problems encountered.
I believe that the settlement problem at the Kansai man-made "island" was mainly due to the existence of thick, very soft clay deposit under the seabed.
To encounter this, they have designed unique type of structures. The columns for the terminal structure can be jack up, as the terminal itself settles. The roof of the terminal was designed in such a way (curved) so that settlement did not produce unpleasant sight on the roof contour. Of course, one of the Japanese geotechnical designer was concerned that the whole island may even sink further. I believe, up to now the terminal has been jacked up by more than 2-3 ft. I guess they eventually may have to deal with putting a sea-wall around the perimeter of the island to ensure that the whole island will not be under water !... or add more fills. So far.. they seem to discuss only about the sinking of the terminal.... which is more heavily loaded. So, I assume there is still enough clearance for the whole island/ground above the sea (it did mentioned in the program, how much the fill was originally placed above the sea level). I have to go back and watch the program again. However, I do recommend that you should watch this program. [sig][/sig]
