Various Measures against Unequal Settlement

If the ground sank equally, there would be no effect on the structures and functions of the airport facilities. If the depths of the settlement vary by location, however, significant problems such as warping in building structures occur. Buildings, especially, are very sensitive to this process. Even a slightly unequal settlement may adversely effect a structure. KIAC takes the following steps against unequal settlement beneath buildings.

• Raft foundation:
  The concrete foundation is directly constructed on the floor of the seabed so that the whole construction would settle equally irregardless of unequal settlement.
• Compaction of the reclaimed layer:
  We have compacted the reclaimed layers so that the reclaiming sand, which is 30 m in depth, would not contract due to an earthquake, for example.
• Balance Established by Soil Removal:
  Sand under heavy buildings is removed in order to equalize the weight over the floor of the seabed as much as possible.
• Jack-up System:
  This is the system that jacks up each of the buildings. It includes installing iron plates in order to adjust and even up the surfaces that slope or lean because of unequal settlement.

Fortunately, ongoing settlement of the first island can be attributed to the settlement of the Pleistocene layer, which is hard and is of almost the same thickness. If the weight of the KIX islands on the Pleistocene layer were the same all over the KIX islands, settlement above sea level would be almost uniform.

In fact, unequal settlement that could cause functional problems with the main facilities such as runways and taxiways has almost not occurred at all.

Jack-up System Used for the Passenger Terminal

The huge passenger terminal is KIX's signature building. Only the main building of the passenger terminal, located at the center of the passenger terminal, has a big basement. Consequently, the main building is lighter than the adjacent structures. Iron ores have been installed all over the bottom of the main building as weight. However, the main building is still lighter than its neighbors. The depth of settlement under the main building is relatively shallow when compared with those of the nearby buildings. The difference in the depth of the settlement generates slight tilts between the main building and the wings of both ends. The tilts are seldom visible to the naked eye. We jack up the pillars under the passenger terminal in order to level the floor of the terminal. The passenger terminal has 9 hundred pillars under the floor. The settlement at each pillar is automatically measured so that we easily know which pillars we have to raise. Unequal settlement has been decreasing as the settlement has been stabilizing. Jacking up of the pillars under the passenger terminal is done biennially.

Basic Concept of the Jack-up System

How the pillar under the passenger terminal is jacked up

Measures against Unequal Settlement under the Passenger Terminal(as of December 2007)