soil mechanics and dynamics team geology and …

Soil Mechanics and Dynamics TeamGeology and Geotechnical Engineering Research GroupPublic Works Research Institute

Damage occurred to the following river dikes.

The number of sites where damage occurred is shown in the right table(As of 22nd Apr., under the direct control of the MLIT).

River dikes damaged significantly by the earthquake were distributed widely in Tohoku and Kanto regions.

東北地整管内

関東地整管内

計

緊急災 29 24 53

一般災 256 188 444

その他 910 702 1,612

計 1,195 914 2,109

1) Tohoku Regional Development BureauMabuchi river, Kitakami river, Abukuma river, Natori river, Naruse river and etc. 2) Kanto Regional Development Bureau Tonegawa river, Arakawa river, Kasumigaura lake, Kuji river, Naka river and etc.

Major Damage

Medium Damage

Minor Damage

Total

Tohoku Kanto Total

Duration of strong ground motion was longer than those recorded by other major earthquakes.

Duration strongly affects liquefaction. Further study on the influence of the duration is required.

0 25 50 75 100 125 150 175 200 225 250 275 300

250

500

750

1000

2成分合成加速度

(gal

)

時間 (秒)

継続時間

初めて50galを観測最後に50galを観測

Determination of duration over 50 gal.

1978年宮城県沖地震

1995年兵庫県南部地震

2003年十勝沖地震

2011年東北地方太平洋沖地震2004年

新潟県中越地震

0

50

100

150

200

50ga

l継続時間

(秒)

開北橋

JMA神

戸

JMA幕

別

JMA川

口町

K-NET築

館

K-NET石

巻

K-NET古

川

K-NET角

田

K-NET大

宮

K-NET那

珂湊

KiK-NET石

下

1978 Miyagiken-Oki

1995Hyogoken-Numbu

2003 Tokachi-Oki

2004 Niigataken-Chuetsu

2011 Tohoku-Chihou Taiheiyo-Oki

Dur

atio

n ov

er 5

0gal

(s

ec)

Acceleration synthesized from two

horizontal components (gal)

Duration

50 gal observed first

50 gal observed lastly

Time(sec)

Many large aftershocks. The damage to the dike near the Noda

bridge was enlarged by these aftershocks.

K-NET Furukawa (Eai river) K-NET Kakuta (Abukuma river)

K-NET Sawara (Tonegawa river)

Dike near the Noda bridge (April 15th)According to an inhabitant, the soil didn’t reach to the shed immediately after the main shock on March 11th.

0

100

200

300

400

500

600

700

3/11 3/18 3/25 4/1 4/8 4/15 4/22

地表

最大加速度

(3成

分合成

) (ga

l)

050

100150200250300350400

3/11 3/18 3/25 4/1 4/8 4/15 4/22

地表

最大加速度

(3成

分合成

) (ga

l)

0

50

100

150

200

250

300

350

3/11 3/18 3/25 4/1 4/8 4/15

地表

最大加速度

(3成

分合成

) (ga

l)

The dike collapsed

Max

imum

Acc

eler

atio

n (th

ree

com

pone

nts

synt

hesi

s m

otio

n) (g

al)

Max

imum

Acc

eler

atio

n (th

ree

com

pone

nts

synt

hesi

s m

otio

n) (g

al)

Max

imum

Acc

eler

atio

n (th

ree

com

pone

nts

synt

hesi

s m

otio

n) (g

al)

強震観測点

被害（緊急災）

被害（緊急災以外）

無被害

国総研・土研調査箇所

国総研・土研未調査箇所

－

－

Survey sites

Other sites

Major damage

Medium or minor damage

No damage

Strong motion monitoring station

Abukuma river

Natori river

K-NET Kakuta

KiK-NET Iwanuma

K-NET Iwanuma

Abukuma river mouth

Natori river mouth

強震観測点



無被害



－

－

Survey sites

Other sites

Major damage


No damage

Strong motion Monitoring station

Shin-Eai river Eai river

Naruse river

Yoshida river Naruse river

Kyu-Kitakami river

Kitakami river

Kyu-Kitakami river mouth

Naruse river mouth

Kitakami river mouthK-NET Furukawa

KiK-NET Onoda

K-NET Ishinomaki

K-NET Toyosato

KiK-NET Kahoku

K-NET Kitakami

（左）1.0k～1.5k

K-NET佐原

K-NET鹿嶋北浦西浦

（左）2.75k-70～2.75k+30

（右）1.75k-70～6.0k

（右）0.8k～1.2k

外浪逆浦

KiK-NET波崎2

（左）18.5k+100～19.0k-11

（右）27.0k+80～27.0k+150

（右）38.5k+292～38.5k+506（右）38.75k-17～38.75k+117（右）39.0k+64～39.75k-50

（右）41.0k-50～41.0k+160

（右）49.0k+55～49.0k+195

強震観測点



無被害



－

－

Survey sites

Other sites

Major damage


No damage


Tonegaw river

Tonegaw river

Tonegaw river mouth

Hitachi river

Nishiura lake Kitaura

lake

Sotona-Sakaura lake

K-NET Sawara

K-NET Kashima

KiK-NET Hasaki 2

（左）67.25k-67～68.0k-25

（右）69.0k+83m～69.0k+199m（右）70.0k-300m～70.0k+130m

（右）70.5k-158m～71.0k

（右）2.0k-110m～2.0k+110m

KiK-NET成田

KiK-NETつくば南

K-NET取手

牛久沼

手賀沼→

KiK-NET江戸崎K-NET江戸崎

強震観測点



無被害



－

－

Survey sites

Other sites

Major damage


No damage


KiK-NET Tsukuba-Minami

K-NET Toride

KiK-NET NaritaTeganuma lake

Ushikunuma lake K-NET Edosaki KiK-NET Edosaki

KiK-NET石下

（左）42.0k-53m～42.0k+6m

（左）35.0k-80m～35.0k+20m

（右）31.8k-100m～31.8k-40m

K-NET岩井

K-NET野田

K-NET久喜

K-NET春日部

江戸川

↓

（右）57.5k+100m～57.5k+300m

（左）58.0k～58.0k+230m

KiK-NET岩槻

K-NET Kuki

K-NET Kasukabe

KiK-NET Iwatsuki

K-NET Noda

K-NET Iwai

KiK-NET Ishige

Edogaw

a river強震観測点



無被害



－

－

Survey sites

Other sites

Major damage

Other damage

No damage


（左）18.5k-172～18.5k+124

K-NET大宮

里

川

（左） -1.0k+151～-1.0k+254

強震観測点



無被害



－

－

Survey sites

Other major sites

Major damage


No damage

Strong motion monitoring stationK-NET Oomiya

Toyo

sato

river

(右)3.5k+300m～4.5k-50m

(左)7.5k+113m～8.0k

K-NET水戸

K-NET那珂湊

KiK-NETひたちなか

涸

沼

川

↑

強震観測点



無被害



－

－

Survey sites

Other major sites

Major damage


No damage


K-NET Mito

K-NET Nakaminato

KiK-NET Hitachinaka

The top of the dike settled in length of about 800 meters. The maximum settlement is about 2 meters.

Collapsed soil covered the adjoining farmland.

Traces of sand boiling were observed in the cracks of dike and at the end of the soil collapse.

Top of the dike

阿武隈川

川裏側のり尻付近

Collapsed soil covering farmland

(右) 32.8k+103～33.0k+170

阿武隈川(右) 30.6k+34～31.4k+160

Classification map of terrain

Abukuma river

Edano site

Abukuma river

Traces of sand boiling in the cracks of the dike and at the end of the soil collapse.

The dike was raised using sandy soil (River bed materials). Old dike and foundation are clay.⇒ Damage was caused mainly due to the liquefaction of saturated area of sandy soil.

Cross section (Tohoku Regional Develpement Bureau)

Clay

Old dike (Clay)River side

Traces of sand boiling

New dike(sandy soil)

The dike collapsed. Traces of sand boiling at the bottom

of cracks. No deformation in the foundation

ground. ⇒ The damage were caused by liquefaction of embankment material.

鳴瀬川

Top and slope of bank

Trace of sand boiling

(左) 29.0k+20～29.1k+280(左) 30.0k～

30.5k+37

鳴瀬川

新江合川

鳴瀬川


Lateral displacement at the toe of slope

Naruse river

Naruse river

Shin-Eai river

Naruse river

Shimonakanome site

Steps and cracks on the slope of the dike constructed on old river.

Large deformation with traces of sand boiling at the toe of slope.

Liquefaction of the foundation ground affected the damage.

Swell and step of road on the slope(Kanto Regional Development Bureau)

江戸川

(左)58.0k～58.0k+230

(右)57.5k+100～57.5k+300

利根川

利根川

江戸川

Slope collapsed(Kanto Regional Development Bureau)


Trace of sand boiling(Kanto Regional Development Bureau)

Satte site

Edogawa river

Tonegawa river

Tonegawa riverEdogawa river

・Yoshida river (1978 Miyagi-Oki)・Kushiro river, Tokachi river

(1993 Kushiro-Oki)・Ushikubibetsu river, Reisakubetu river

(2003 Tokachi-Oki)・Naruse river (2003 Miyagiken North)etc.

Same mechanisms are observed in the following sites and earthquakes.

(a) 地震前

(b) 地震～液状化の発生

(c) 液状化～堤体の変形

雨水の浸入等による閉封飽和域の形成

圧密沈下による堤体下部のめり込み基礎地盤

=軟弱粘性土

堤体=砂質土

地震動による閉封飽和域の液状化⇒流体的挙動

地震動

(a) Dike has sunk with the consolidation of soft clay base layer.⇒ Water is trapped easily. Saturated area is enlarged.

(b) Saturated sand is liquefied by an earthquake.

(c) Dike settles and spreads to lateral direction.

地震動

噴砂の貫入

堤体の陥没(土塊の沈下)

のり尻の側方流動(土塊の水平移動)

噴砂の流出

Sand Saturated area

Settlementwith consolidation

Soft clay

Liquefaction of saturated area

Earthquake motion

(a) Before earthquake

(b) During earthquake ~ Liquefaction

(c) Liquefaction ~ Deformation

Dike settles

Lateral displacement

Liquefied sand flows.

Sand boiling

The dike was damaged by earthquake in 2003 and recovered with measures of ground improvement, drainage and etc.

No damage at the site with measures. Minor damage was observed in the

adjoining sites without measures.Cross section

No damage( the ground under the dike was improved by cement.)

Damage at the upstream site without measures

Improvement

Naruse river

River dikes damaged significantly by the earthquake were distributed widely in Tohoku and Kanto regions.

It is assumed that long duration of the earthquake motion is a factor of the large damages and the damages may be extended by the large aftershocks.

The damage at sites of Abukuma, Naruse, Eai and etc. in Tohoku region were caused by liquefaction of saturated area in the river dikes.

Since no damage was observed at the sites with measures (ground improvement and etc.), the effects of measures was confirmed.

soil mechanics and dynamics team geology and …

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