Kansai International Airport is an artificial island airport located 5km offshore in Osaka Bay, Japan. It was constructed to avoid noise pollution on residential areas and land disputes. The airport was built in two phases, with the first phase in 1994 reclaiming 510ha of land through driving 1 million sand columns and depositing 180 million cubic meters of soil. The second phase in 2007 expanded the airport with another 545ha island built 200m from the first, using advanced ground improvement techniques like sand drains, sand piles and deep soil mixing to stabilize the soft clay layers below.

1. KANSAI INTERNATIONALAIRPORT (KIX)- A CASE
STUDY OF SAND DRAINS
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2. KANSAI INTERNATIONAL AIRPORT
(Furudoi,2006)
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3. INTRODUCTION
• Kansai International Airport (KIX) is an international airport located
on an artificial island in the middle of Osaka Bay
• First 24-hour operational airport in Japan
• Opened on 4 September 1994
• Constructed 5km offshore in Osaka bay as a man-made island
• Diverse accesses by highway, railways and high-speed ferry are provided
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4. Kansai region
Osaka bay
Kansai International
Airport
5km
Location of Kansai International Airport
(Furudoi,2006) 4

5. • In 1990, a three kilometer bridge was completed to connect the
island to the mainland at Rinku Town
• Constructed mainly to
Avoid the impact of aircraft noise on residential areas
Avoid land-acquisition disputes
• Construction of Island I began in 1987 - began operation in
1994
• Construction of Island II began in 1999 - began operation in
2007
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6. NATURAL CONDITION
• Water depth of the construction site - 18m to 20m
• The layers below the seabed consist of a soft layer of Holocene clay
immediately below the seabed surface and alternative layers of Pleistocene
clay and sand/gravel
• The depth and thickness of each clay layer gently increases as it goes
towards offshore side
• Holocene clay layer is particularly thick and weak
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7. • Holocene clay layer should be improved so as to minimize the residual
and uneven settlement by driving many sand piles
• As a result, it is estimated that the settlement of Holocene clay layer
will be completed during the construction
• It is difficult to improve the Pleistocene clay layers technologically
• The natural Pleistocene clay layers continue to subside after the airport
is opened
• Long-term settlement of the Pleistocene clay layer should be predicted
and reflected in the design of thickness of reclamation
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8. THE FIRST PHASE OF THE PROJECT
• An airport island of about 510ha was reclaimed
• 3,500m runway, takeoff/landing facilities and terminal facilities were provided
• 1 million sand columns were driven to improve Holocene clay layer
• This was followed by construction of an 11km long seawall around the island
• Then reclamation inside the seawall required 180 million m3 of soil
• After reclamation work, airport facilities including the run-way and the
passenger terminal were built
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9. THE SECOND PHASE OF THE PROJECT
• Project involved development of another man-made island of 545ha
land, 200m off the existing air-port island
• Provided a 4000m run-way
• The thickness of compressible clay layers and the water depth of the
second phase construction site were greater than those of the first phase
• Extraordinary large-scale construction was conducted in a limited
period of time, overcoming these severe conditions of settlement
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10. CONSTRUCTION
• An artificial island - 4 km long and 2.5 km wide
• Ground improvement works were carried out
• The seawall was built all round the island site
• The reclamation work was carried out which consists of three stages:
soil dumping by hopper barges, soil heaping by re-claimer barges and
multi-layered construction by bulldozers and rollers
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11. Procedure of construction
(Furudoi,2006) 11

12. GROUND IMPROVEMENT WORK
• The ground improvement work was carried out throughout the entire
seawall and reclamation area.
• It was obtained by
Spreading of sand blanket
Using ground improvement techniques
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13. Spreading of sand blanket
• 1.5m thick layer of sea sand was carefully laid and spread evenly over
the seabed as a blanket
• The sand blanket allows the water discharged from Holocene clay layer
to pass out and disperses the load caused by the seawall construction
and reclamation
• Two methods were available
Pump method
Tremie pipe method
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14. (a) Pump method (b) Tremie pipe method
(Furudoi,2006) 14

15. • Seto Inland Sea – it is a source of sea sand
• Because of depletion, substitutes were used in some part of sand
blanket and are:
 Graded aggregate of nonstandard crushed stone – has larger
grain size - used for upper part of sand blanket as a cushion to
reclamation
Imported sand from China Korea
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16. Ground improvement
• The ground improvement was carried out by the following methods:
Sand drain method (SD)
Sand compaction pile method (SCP)
Deep mixing method (DM)
Marine plastic drain method (MPD)
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17. SD : Sand drain method SCP : Sand compaction pile method
DM : Deep mixing method MPD: Marine plastic drain method
Ground improvement applied in the construction
(Furudoi,2006) 17

18. Sand drain method
• A sand drain method was applied to most parts of the seawall construction
area and all of the reclamation area
• 40cm diameter Sand piles were driven into Holocene clay layer using sand
barges
• Domestic sea sand was used for sand piles
• Spacing of the sand piles - 2.5m × 2.5m square grid, excluding the area
beneath the seawall - 1.6m × 2.5m rectangular grid
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19. Sand-piling barge Spacing of sand drain piles
(Furudoi,2006)
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20. • Holocene clay layer becomes greater towards offshore side, the sand piles
in the second construction site were longer than those in the first
• For promoting consolidation, the sand piles were driven to the sand layer
beneath Holocene clay layer
• Thickness of Holocene clay layer was obtained by boring
• Sand piles were simultaneously driven in the area of 30m
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21. Sand drain
(Furudoi,2006) 21

22. CONCLUSION
• Kansai International Airport - fundamental solution to the problem of the aircraft
noise pollution and to meet the increasing demand for air transportation
• Ground improvement methods is to accelerate the consolidation of the seafloor
• Four methods: sand drain, sand compaction piles, marine plastic drain and deep
mixing
• The reclamation work consists of three stages: soil dumping, soil heaping and
multi-layered construction
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23. REFERENCE
Furudoi(2006), Second phase construction project of Kansai International Airport - Large-
scale reclamation works on soft deposits -, Kansai International Airport Land
Development Co., Ltd., Japan
https://en.wikipedia.org/wiki/Kansai_International_Airport
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