Volume 1, Issue 1 September 2016

ReportDamage survey after The 2016 Kumamoto Earthquake-Confirmation of tough Implant structureDr. Tadahiko Okumura
Engineering Advancement Association of Japan
Director of Geo-space Engineering Center[The 2016 Kumamoto Earthquake]
The great earthquakes more than seismic intensity-Magnitude- 7 by Japan Meteorological Agency occurred twice inKumamoto Prefecture in Kyushu Island in this April and severe damages were induced. For example, there were a lot ofcollapses of wooden houses, cracks in levees, large-scale slope falls, collapse of Aso bridge and etc. (See left photo).
It was the first case that two great earthquakes more than Magnitude 7 within few days occurred in Japan.
[Damage observation by survey team]
The field damage survey team investigatedearthquake damages induced by The 2016
Kumamoto Earthquake in this April, especially ofImplant structures (See Reference) constructed in
Kumamoto Prefecture, for 3 days from May 23 to25, because a lot of Implant structures wereconstructed in Kumamoto Prefecture. Dr.
Kusakabe, Chairman of IPA led the team and 10members including IPA and JPA (Japan Press-inAssociation) joined. Comprehensive investigation
was done by the IPA and JPA joint team in order toinvestigate from the point of design, construction
and maintenance.

Cracks in levees

23 April 2016, Midorikawa

Large-scale slope falls

Source: Ministry of Land, Infrastructure, Transport andTourism, Kyushu Regional Development Bureau

18 April 2016, Minami-Asomura[Reference / Implant structure]
The Implant structure consists of a structuralmember that is combined with a frame andfoundation that are embedded into the groundwhere they are securely supported by the ground.
The structure carries horizontal and vertical loads,
using “the scale of the allowable structuralmember” and “the depth of penetration into theground”.

Collapse of Aso bridge

8 May 2016, Minami-Asomura

9Volume 1, Issue 1 September 2016

Stalked steel pipe walls at access line

Main railway line
Access railway line

Lateral displacement to levee at main line

Photo 1

The typical example of earthquake damages is a viaduct construction site of local railway and Kyushu Shinkansen (Bullettrain) between Fukuoka Prefecture and Kagoshima Prefecture near Kumamoto station of JR Kyushu Railway Company.
The slight cracks on the ground surface in access railway line were investigated at the site of continuous steel pipe wallsof diameter 800 mm. However main body of Implant structures had no damage, though levee walls and soils adjacent tomain railway line deformed largely laterally (See photo 1).
At the discharge channel sites ineast area in Kumamoto Prefecture,
there were no damage at the levees
reinforced by concrete sheet piles
and embankment levees have somedamages (See photo 2).

Filled levee were damaged

No damages to implant levee withsteel sheet piles reinforced byconcrete

8 May 2016, Minami-Asomura

Dr. Kusakabe pointed out that “We
confirmed expected results against
earthquake occurrence for steel
sheet piles and steel piles. In case oflevees and dikes reinforced by steel
sheetpiles,
etc.,
collapsemechanism was concentrated in no
reinforced portions and totalcollapse was avoided. In order toexpand the above mentioned
effectiveness, we like to examine
scientifically structure types, depthof penetration into the ground andetc. and proceed to specify in design method.”

Photo 2The team will summarize in survey report and disclose in Web site and etc. in near future and include this survey resultsin Technical seminars or workshops organized by JPA and IPA in order to demonstrate the advantages of Implant structures.
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