Proceedings of the International Symposium on Engineering Lessons Learned fromthe 2011 Great East Japan Earthquake, March 1-4, 2012, Tokyo, JapanDAMAGE CAUSED TO SHINKANSEN STRUCTURES
BY THE GREAT EAST JAPAN EARTHQUAKEAND EARLY RESTORATION
Masashi KOBAYASHI1, Koichiro MIZUNO2, and Tadayoshi ISHIBASHI3
1

Manager, Structural Engineering Center, East Japan Railway Company,
Tokyo, Japan, masa-kobayashi@jreast.co.jp
2
Engineer, Structural Engineering Center, East Japan Railway Company,
Tokyo, Japan, kou-mizuno@jreast.co.jp
3
General Manager, Structural Engineering Center, East Japan Railway Company,
Tokyo, Japan, ishibashi@jreast.co.jp

ABSTRACT: This paper outlines the damage to Shinkansen structures caused by theGreat East Japan Earthquake and the early restoration of the damaged structures.
Observations were made to investigate the severity of the damage to structures and themechanism of the damage. Although there was some damage to viaduct columns andbridge piers, crippling damage such as the fall of bridge girders were not observed. We
consider that the seismic rehabilitation of the columns and piers, based on the priorities
set by the seismic performance of RC members is effective to prevent seismic damage.
Key Words: Great East Japan earthquake, seismic damage, failure mode, viaductcolumns, bridge piers, seismic rehabilitation, seismic performance,
restoration

1. INTRODUCTION
This paper describes the outline of damaged structures of the Tohoku Shinkansen caused by the Great
East Japan Earthquake and early restoration of the damaged structures. In this paper, authors mainly
discuss the damage to reinforced concrete (RC) members, and especially, focus on the seismic
performance of viaduct columns and bridge piers. Additionally, we confirmed that the Tsunami did notreach the Shinkansen.
The Great East Japan Earthquake struck on March 11, 2011, and recorded the largest earthquake inJapanese history at a magnitude of 9.0 on the moment magnitude scale. Furthermore, many strong
aftershocks such as an earthquake recorded on April 7 also occurred. The main earthquake generated
widespread and strong ground motion lasting for a long time, and caused damage to East Japan
Railway Company (JR East) structures. Therefore, this earthquake caused the suspension of Tohoku
Shinkansen operations. The recorded ground motion in Sendai by the main shock is shown in Fig. 1.
To compare the duration of the earthquake motion, the motion by the 1995 Hyogoken-Nambu (Kobe)
Earthquake is also shown in Fig. 1. From this figure, it is observed that the lasting time of the Great
East Japan Earthquake was much longer than the 1995 Hyogoken-Nambu Earthquake in which serious

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Acceleration (gal)2000
K-NET Sendai [NS]
1000
0
-1000
Maximum：1517gal
-2000
0

50

100
Time (sec)

150

200

a) Ground motion by the Great East Japan Earthquake at K-NET Sendai
Acceleration (gal)2000
JMA Kobe [NS]
1000
0
-1000
Maximum：818gal
-2000
0

50

100
Time (sec)

150

200

b) Ground motion by the 1995 Hyogoken-Nambu Earthquake at JMA Kobe
Fig. 1 Comparison of the ground motion between by the Great East Japan Earthquake
and by the 1995 Hyogoken-Nambu Earthquake
damage was suffered to many RC structures.
To investigate the severity of the damage, immediate observations were made along the Tohoku
Shinkansen. Fig. 2 shows the numbers and distribution of the damaged structures along the Tohoku
Shinkansen Line. This figure excludes the damage to electrical structures such as electric poles andoverhead wires. Shown in Fig. 2, the Shinkansen sustained damage at approximately 1,200 sites along
about 500 km between Omiya and Iwate-Numakunai stations. Although there was some damage to
viaduct columns, fatal damage such as the fall of bridge girders, which had occurred in the 1995
Hyogoken-Nambu Earthquake, was not observed. Main examples of the damage to JR East’s railway
structures were damage to viaduct columns at about 100 sites, displacement of bridge girders at 2 sites,and damage to bridge shoes at about 20 sites.
With the results of the observations, we proposed an early restoration method in two steps:“permanent repair” and “reinforcement”. Technique for urgent and permanent repairs had beendeveloped and refined through past restorations from seismic damage. JR East had started restoring
the damaged structures caused by the main earthquake immediately following the observations. By
this approach, more than 90 % of the damaged structures had been restored by the timing of thestrongest aftershock on April 7.
As mentioned above, the characteristic of the earthquake is a large number of strong aftershocks.
The aftershock on April 7 caused damage to the Tohoku Shinkansen structures at about 550 sites. The
extent of the damaged structures caused by this aftershock was narrower than the extent of the main
shock. However, more severe damage was observed at several locations such as between Sendai to
Ichinoseki stations. Crippling damage was not confirmed. The aftershock on April 7 also caused thesuspension of the Shinkansen operations. Main examples of damage caused by the aftershock on April
7 were damage to viaduct columns at about 20 sites, displacement of bridge girders at 7 sites, anddamage to bridge shoes at about 10 sites.

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Damaged by the earthquake
on March 11, 2011

Damaged by the earthquake
on April 7, 2011

Shin-Aomori

Shin-Aomori
Hachinohe

Hachinohe

Iwate-Numakunai

Iwate-Numakunai

MoriokaMorioka

Kitakami

Kitakami

Ichinoseki

Ichinoseki

Fukushima

SendaiSendai

Fukushima

Koriyama

Koriyama

Nasushiobara

Nasushiobara
Utsunomiya

Utsunomiya

Oyama

Oyama
Omiya

Omiya

Tokyo

Tokyo

[Legend]
10 sites
01 site[Legend]
10 sites
01 siteFig. 2 Numbers and distribution of the damaged structuresin the Tohoku Shinkansen Line

2. DAMAGE CAUSED TO RC SHINKANSEN STRUCTURES
2.1 Outline of the Tohoku Shinkansen RC structures
RC structures of the Tohoku Shinkansen Line from Omiya to Morioka stations were constructed inconjunction with the opening of the line in 1982. About 58 % of its length is RC viaduct and 13 % isbridges.
In Japan, several serious earthquakes have occurred, such as the 1995 Hyogoken-Nambu
Earthquake, Sanriku Minami Earthquake in 2003, and Niigata Chuetsu Earthquake in 2004. Damage
caused by the 1995 Hyogoken-Nambu Earthquake promoted the revision of earthquake resistantdesign codes in Japan which brought about the need to aseismically reinforce RC structures
throughout Japan. RC railway structures in JR East also needed countermeasure works to improve theseismic performance of RC members and to prevent severe seismic damage such as the fall of girders
and collapse of RC viaducts and bridges. JR East has accordingly been conducting the seismic
rehabilitation of RC viaduct columns and bridge piers on a preferential basis in the seismic
performance of the RC members.

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A
Collapse of columns,
fall of girdersBB
Significant deformationof longitudinal bar,widespread fall of coverconcrete,settlement of railroad
track

B
Some amount of deformation of longitudinalbar,widespread fall of coverconcrete,no settlement of therailroad track

C
Cracks in coverconcrete,partial fall of coverconcrete*Photo shows example in
Kobe Earthquake.

Fig. 3 Gradation of seismic damage caused to RC column members

2.2 Damage to RC viaduct columns
Considering seismic damage, the failure modes of RC members are classified into two types according
to the seismic performance: shear failure and flexure failure. The basic concept of seismic
rehabilitation is to prevent shear failure of RC viaduct columns and bridge piers caused by large
seismic temblors which result in the collapse of RC viaducts and bridges.
In Tohoku Shinkansen structures, the seismic rehabilitation to RC viaduct columns with deficientseismic performance classified as shear failure type has been completed. In addition, seismic
rehabilitation has been planned for RC columns with low seismic performance classified as the flexure
failure type. The damaged columns were categorized as flexure failure type and had been planned to
conduct the seismic rehabilitation.
Fig. 3 shows the gradation of seismic damage caused to RC column members, the photos in Fig. 3
showing typical seismic damage of each level (Ishibashi et al. 1997). We consider that these levels
could be classified by the degree of damage of RC members and restorability such as duration of work
etc. In Fig. 3, damage level “A” indicates situations where the collapse of a structure such as RC
columns or fall of the bridge girders is observed. Damage level “BB” shows situations where
significant deformation of longitudinal reinforcing bar, widespread fall of cover concrete of RC
columns, cracks penetrating into core concrete, and settlement of railroad track are observed. Damagelevel “B” indicates situations where some amount of deformation of longitudinal reinforcing bar,widespread fall of cover concrete of RC columns, and cracks penetrating into core concrete areobserved, but settlement of railroad track is not observed. Damage level “C” shows situations where
cracks in cover concrete and partial fall of cover concrete are observed, while settlement of railroad
track is not observed. We consider that levels A, BB, and B are the types of damage sufficient tosuspend Shinkansen operations. Furthermore, we consider that damage level C should not suspend theoperations, but requires restoration in terms of durability.
Observations were made along the Tohoku Shinkansen to investigate the severity of the damage to
RC structures caused by earthquakes and the mechanism of the damage. Table 1 shows the percentage
of damaged RC columns as to the whole number of RC columns according to section between Omiya
and Morioka stations. From Table 1, it is found that the level A damage was not observed, and thatdamaged columns in level BB, B, C, were observed in broad area. And, Table 1 suggests that thepercentages of BB and B are both about 0.1 %, and that of C is 0.3%. Therefore, it can be determined1346

Table 1 The percentage of damaged RC columns as to the whole number of RC columns
caused by the main earthquake on March 11, 2011, according to section
SectionsA
From Omiya (30.3 km) to Nasushiobara (157.8 km)
From Nasushiobara (157.8 km) to Fukushima (272.8 km)
From Fukushima (272.8 km) to Sendai (351.8 km）
0
From Sendai (351.8 km） to Ichinoseki (445.1 km）
From Ichinoseki (445.1 km) to Morioka (535.3 km)
Total (Numbers of total columns about 50,000）
0*Numbers in parentheses show the distance from Tokyo station.

BB
0
0
0
0.0
0.1
0.0

B
0
0.2
0.4
0.0
0.3
0.1

C
0.0
1.1
1.0
0.1
0.3
0.3
[unit: %]Photo 1 Example of seismic damage of RC viaduct columns (damage level BB)

that the rate of damaged RC columns in the observed area is extremely low.
The example of the severest seismic damage of RC columns by the main shock is shown in Photo
1. We evaluated this seismic damage as BB. The seismic damage was located in the vicinity of theupper edge of columns. Settlement of railroad track of about 50 mm was also observed at this site. The
damaged structure shown in Photo 1 is an RC rigid frame viaduct with 1 story and 3 spans, andsupports the simple RC girders. The damaged columns are located at end of the block and their lengthis about 0.4 m shorter than the length of the columns located at the intermediate part of the block. It isfound that the seismic damaged columns with track settlement are about 10 in total when we add thenumbers of damaged columns caused by the main earthquake on March 11 and aftershock on April 7.
Among these, damaged columns with falling of core concrete were observed. We assume that thecolumn with prominent protrusion of core concrete damaged by the main quake was affected by its
long duration.
As mentioned above, JR East has implemented seismic rehabilitation to RC columns with low
seismic performance, and has completed implementation on very low-performance columns. In someRC railway viaducts, the space under the viaduct is used as stations, shops, and other buildings.
Therefore, the seismic rehabilitation must deal with various obstructions such as partition walls andequipment. In this case, the rehabilitation site is a confined space, which means restrictions on the useof large construction equipment such as cranes. Often, construction schedule restrictions also apply, so
a suitable method designed taking into account the various conditions at each site must be considered.
JR East has developed various original kinds of the seismic rehabilitation techniques to resolve all
restrictions adequately and economically.
Steel plate jacketing method (Ishibashi et al. 2004) is used most commonly for railway RC viaduct1347

Photo 2 Impact by earthquakes
on columns with seismic
rehabilitation by Steel platejacketing method using
indented joints

Photo 3 Impact by earthquakes
on columns with seismic
rehabilitation by Rib-Bar
methodPhoto 4 Impact by earthquakes
on columns with seismic
rehabilitation by Single-facemethodcolumns for seismic rehabilitations of RC columns. Meanwhile, columns in limiting situations need tobe reinforced by original techniques developed by JR East. Examples of impact on aseimicallyreinforced RC viaducts by the earthquakes of March 11 and April 7 are shown in Photos 2 to 4. In
Photo 2, we observed that the column with the seismic rehabilitation only had the remarkably minor
damage where the paint on the steel plate came off at butt joint. Furthermore, as shown in Photos 3
and 4, very minor damage was observed in columns that were aseismically reinforced by techniquesdeveloped by JR East. Thus, it is confirmed that the aseismically reinforced columns of RC railway
viaducts suffered significantly less damage. Additionally, we consider that JR East’s seismic
rehabilitations of RC railway columns could be effective in preventing seismic damage.
2.3 Damage to RC bridge piers
We also investigated the severity of damage to RC railway bridge piers caused by the earthquakes
along the Tohoku Shinkansen. Observations suggested that the damage of RC piers was mainly caused
at cut-off of the longitudinal reinforcing bars. The categories of observed seismic damage included thepartial fall of cover concrete and cracks, mainly occurring at cut-off. Additionally, we did not observedamage by shear failure leading to collapse of pier or fall of bridge girders. We consider that this could
be the achievement of seismic rehabilitations to RC piers which JR East had been carrying out to thesame degree as reinforcement of RC viaduct columns.
Fig. 4 shows gradation of seismic damage caused to RC bridge pier members, and the photos in
Fig. 4 show typical seismic damage of each level. Each damage level was determined by the same
situations as RC viaduct in Fig. 3.
Table 2 shows the percentage of damaged RC piers to the whole number of RC piers according tosection between Omiya and Morioka stations. From Table 2, it is found that damage of piers in neither
level A nor BB was observed, but damage of piers in levels B and C was observed over a broad area.
In addition, Table 2 indicates that the percentage of B is about 0.1 % and that of C is 0.2%,
respectively. Thus, it can be deduced that the rate of damaged RC piers in the observed area isextremely low.
An example of seismic damage in RC piers by the main shock is shown in Photo 5. We evaluatedthis seismic damage as B. The damaged structure shown in Photo 5 is on RC bridge pier 4.5 m in

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A
Collapse of columns,
fall of girdersBB
Significant deformationof longitudinal bar,widespread fall of coverconcrete,settlement of railroad
track*Photo shows example in
Kobe Earthquake.

*Photo shows example in
Kobe Earthquake.

B
Some amount of deformation of longitudinalbar,widespread fall of coverconcrete,no settlement of therailroad track

C
Cracks in coverconcrete,partial fall of coverconcrete

Fig. 4 Gradation of seismic damage caused to RC bridge pier members
Table 2 The percentage of damaged RC piers as to the whole number of RC pierscaused by the main earthquake on March 11, 2011, according to section
SectionsA
From Omiya (30.3 km) to Nasushiobara (157.8 km)
From Nasushiobara (157.8 km) to Fukushima (272.8 km)
From Fukushima (272.8 km) to Sendai (351.8 km）
0
From Sendai (351.8 km） to Ichinoseki (445.1 km）
From Ichinoseki (445.1 km) to Morioka (535.3 km)
Total (Numbers of total piers about 8,000)
0*Numbers in parentheses show the distance from Tokyo station.

BB

0

0

B
0
0
0.3
0.1
0
0.1

C
0
0.2
0.5
0.1
0
0.2
[unit: %]Photo 5 Example of seismic damage of RC bridge piers (damage level B)
diameter and 18.0 m in height, and supports pre-stressed concrete (PC) box-shaped girders. The box
girders are 50 m and 35 m in length. We observed partial falls of cover concrete and cracks at cut-off
at the seismically damaged pier.
JR East has also been implementing a program of seismic rehabilitation of RC piers with deficient1349

Table 3 Resumption date of the Tohoku Shinkansen operations and work duration of permanent repairs
Resumption
date
From Tokyo (0 km) to Omiya (30.3 km)
Mar. 12From Omiya (30.3 km) to Nasushiobara (157.8 km)
Mar. 15
From Nasushiobara (157.8 km) to Fukushima (272.8 km)
Apr. 12From Fukushima (272.8 km) to Sendai (351.8 km）
Apr. 25
From Sendai (351.8 km） to Ichinoseki (445.1 km）
Apr. 29
Apr. 7
From Ichinoseki (445.1 km) to Morioka (535.3 km)
Apr. 23
Re-suspended by aftershock on Apr. 7
From Morioka (535.3km) to Shin-Aomori (713.7 km)
Mar. 22
Apr. 13
Re-suspended by aftershock on Apr. 7*Numbers in parentheses show the distance from Tokyo station.
Sections

Days from
Mar. 11
1
4
32
45
49
27
11
-

Days from
Apr. 7
5
18
22
16
6

seismic performance, and has completed the program for low performance piers. The basic concept of
the rehabilitation of RC piers is to improve seismic performance of the members at the base of pierand cut-off. Seismic rehabilitation method using RC jacketing is applied most commonly for railway
RC bridge piers.
In some RC railway piers, the space around the pier is incorporated into river embankment, and is
deeply buried. In other cases, some piers are located in the river. Therefore, the seismic rehabilitationmust deal with various limitations, and we need to adopt suitable methods designed taking into
account the various conditions on site. JR East has developed various original kinds of seismic
rehabilitation which have adequate and economic application to RC bridge piers.

3. EARLY RESTORATION OF RC SHINKANSEN STRUCTURES
3.1 Outline of restoration work of the Tohoku Shinkansen structures and operations
RC structures of the Tohoku Shinkansen were restored quickly, by means of timely and adequate
evaluation of the damaged RC members and permanent repairs. Table 3 shows the resumption date of
Tohoku Shinkansen operations and work duration of permanent repairs. In Table 3, the duration of
repair work includes the course of action from the earthquake occurrence, investigations, permanent
repair work, running test of Shinkansen cars, and resumption of operation. Table 3 indicates that theelapsed time to re-operation suggests the severity of seismic damage of RC members. So, areas withmost elapsed days required longer to restore. The earliest resumption was after 1 day, and the latest
was after 49 days. Moreover, as mentioned above, work duration in Table 3 includes time ofobservation and commission. And so, we consider that permanent repair work to the damaged RC
members was accomplished in short term considering the extent of the damaged area by theearthquakes. In addition, a strong aftershock occurred on April 7 which caused seismic damage to the
Shinkansen structures again, and this aftershock required JR East to restart observations along the
Shinkansen Line as an initial step in further restoration work. Although repair work prolonged as aconsequence of the aftershock on April 7, it was found that the damaged structures were restored for
operation of Tohoku Shinkansen within about 3 weeks.
Restoration techniques have been refined through adequate engineering judgment and timely
decision-making as to method of repair work by JR East based on experience through past earthquakes.
Engineers and techniques obtained from the past restoration work in maintenance and construction
companies are also considered important. We consider that all of these factors facilitated therestoration of the Tohoku Shinkansen Line in just 49 days.

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Photo 6 Restored RC columns

Photo 7 Restored RC pier3.2 Restoration work of RC viaduct columns
Repair work of RC viaduct was conducted taking priority of the damage level of the members.
Therefore, the severity of the damaged members through the observations was firstly determined, andthen the principle to restore the damage was decided. As for the repair work, JR East proceeded withthe restoration of damaged structures sequentially from damage level BB, B to C. With consecutive
restoration, it is considered that the materials and labor power for the repair work were able to beobtained effectively, and the work duration shortened.
Photo 6 shows the restored columns which sustained level BB damage. The repair procedure of
the damaged columns in level BB as follows: First, steel temporary support was placed beneath thecross beam, and then the longitudinal reinforcing bars were cut off tentatively. Next, the concrete slab
supporting the railroad track was lifted by jacks. After being jacked up, the longitudinal reinforcing
bars were rearranged at the appropriate position, and were connected up to the cut reinforcing bars
with welded joint. After the treatments of the longitudinal bars, the transverse reinforcing bars were set
at proper position. Then, the chemical materials were grouted between the cracks. And finally, themortars were grouted to recover the member. With this course of work, we consider that the permanent
repair work to restore the seismic performance of the damaged columns in level BB up to the originallevel or higher was conducted. Further, the work duration at the site shown in Photo 6 was about 7
days.
3.3 Restoration work of RC bridge piers
The repair work of RC piers was also carried out taking priority of the damage level of the members.
Photo 7 shows the restored pier which sustained level B damage. The repair procedure of this damaged

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pier was as follows. The chemical grouting between the cracks was conducted first. And then, thetransverse reinforcing bars were rearranged at the appropriate position. Finally, the cover was refilledwith mortar. Further, the work duration at the site shown in Photo 7 was only about 8 days.

4. CONCLUSIONSIn this paper, authors have indicated the outline of seismic damage of the Tohoku Shinkansen
structures and the early restoration. The conclusions from this paper can be summarized as follows:(1) Although the extent of the damaged structures was broad, the percentage of damaged structures as
to the total number of structures was extremely low.
(2) No fatal damage which led to the collapse of the structure systems in the Tohoku Shinkansen had
been observed.
(3) The seismic damage caused to RC viaduct columns was mainly located in the vicinity of the upperedge of columns. And, that of RC bridge piers was mainly located at cut-off.
(4) The columns and piers with seismic rehabilitation had the significantly minor damage. Therefore,
authors consider that the scheduled and consecutive seismic rehabilitation to RC structures by JR Eastis effective to prevent seismic damage.
(5) Work duration of the restoration of the damaged Shinkansen structures could be shortened throughrefined techniques.

REFERENCES
Kyoshin Net (K-NET) homepage, http://www.k-net.bosai.go.jp/
Ishibashi, T., Ikeda, Y., Kanno, T., and Okamura, H. (1997). “The study on earthquake resistance on
design and damage of reinforced concrete viaduct.” Journal of Structural Mechanics andEarthquake Engineering, Vol. I-39, 95-103. (in Japanese)
Ishibashi, T., Tsuyoshi, T., and Kobayashi, K. (2004). “Seismic retrofitting methods newly developed
for railway concrete structures.” Journal of Advanced Concrete Technology, Vol. 2, No.1, 65-76.

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