No.36 August 2012STEEL CONSTRUCTIONTODAY & TOMORROW

http://www.jisf.or.jp/en/activity/sctt/index.html【 i n o - r u 】

祈 (ino-ru) in Japanese, or "pray" in English:
Seeking divine intervention

We pray for a speedy return to normalcy for the victims of
the Great East Japan Earthquake, and for the earliest possible
restoration of tranquility in the disaster-stricken area.

In this issue.....
Special Feature: The 2011 Great East Japan Earthquake

Photo: Port and Airport Research Institute1 How to Interact with and Prepare for Natural Disasters?
3 Coastal Facilities: Lessons Learned from the Quake and Tsunamis
Published Jointly by

6 Damage to River Levees and Measures for Restoration andReconstruction

9 Liquefaction-induced Damage to Houses and Buried Lifelines

The Japan Iron and Steel Federation

15 Treatment of Debris and Tsunami Deposits, and Their Effective

Japanese Society of Steel Construction

Steel Application Technology

Utilization for Restoration and Reconstruction

18 Basic Details about Corrosion and Corrosion ProtectionPreface: Special Feature on the 2011 Great East Japan Earthquake

How to Interact with and Prepare for
Natural Disasters?
by Nobuo Shuto
Emeritus Professor, Tohoku University

Steady Social Infrastructure
Improvement

In Japan, it was after 1960 that the nation’s
inventory of social infrastructure, including
structures for dealing with natural disasters,
began to increase. A major reason for progress in this area was the income doublingplan and the resulting availability of thefunding required for infrastructure improvement and development.
Civil engineering construction materials
changed. The soil, wood and stone that had
served as the major materials in conventional civil engineering were replaced withsteel and concrete. Scaffolding logs were
replaced with steel pipes. Vibrators came

Nobuo Shuto:After entering the Ministry of Construction in 1957, he became researcher of the
Ministry’s Public Works Research Institute in 1960.
He became professor of School of Engineering,Tohoku University in 1977, and of the University’s
Disaster Control Research Center in 1990. His
professional field is tsunami engineering.

into use for concrete placement. Similarly,
the extensive use of construction machinery
led to faster construction times andimproved structural reliability.
Previously, even major national highways such as Routes 1 through 9 weregravel roads, but nowadays even the farmroads running between fields are finely
paved. Embankments have been built anddams have been constructed with the resultthat flooding is rare. As can be seen in Fig.
1, the number of deaths caused by natural
disasters dropped sharply after 1960.
Tsunami Preparation

What countermeasures were taken against

tsunamis? Before the Showa Sanriku Tsunami of 1933, the major countermeasuresagainst tsunamis, except for a few examples,
were to live on high ground and to seek
refuge when a tsunami struck. Even after
1933, the primary countermeasure was to liveon high ground. But, in Kamaishi, Taro andthree other urban areas in the Tohoku area
where spacious land could not be secured,
tidal embankments and seawalls were constructed.
At that time, it was recognized that radios
could be used to warn of tsunamis and it wasthen that radio usage began to increase. In
1941 a radio-based tsunami alert system was
first aimed at the Sanriku area (eastern-mostFig. 1 Trends in the Dead and Missing due to Natural Disasters in Japan

Great East Japan
Earthquake

Mikawa Earthquake: 2,306
Makurazaki Typhoon: 3,766

Great Hanshin
Earthquake: 6,437
Ise Bay Typhoon:
5,099

Missing: 8,499

Fukui Earthquake:
3,769

Dead: 15,270(persons)

Note:
1945: Dead and missing due to major disasters (Chronological Scientific Tables); 1946-1952: Japan Natural Disaster Report; 1953-1962: Dataof the National Police Agency; From 1963 onward: Data of the Fire and Natural Disaster Management Agency; Dead in 1995: Including 919
disaster-related deaths in the Great Hanshin Earthquake (data of Hyogo Prefecture); 2010: Preliminary report for dead and missing; Dead andmissing persons in 2011: Data for the Great East Japan Earthquake (as of May 30, data of the Headquarters for Emergency Disaster Control)
Source: White Paper on Disaster Prevention for 2011
1 Steel Construction Today & Tomorrow August 2012

Pacific coast of Japan). In 1952, the target
area was expanded nationwide and the Meteorological Business Act was implemented.
Just before 1952, a temporary tsunami alert
system worked successfully against a tsunami
caused by the 1952 Tokachi-Oki Earthquake.
Are Tsunami-prevention Structures
Trustworthy?

It was with the tsunami generated by
the1960 Valdivia earthquake in Chile thattsunami-prevention structures became themain countermeasure against a tsunami.
This tsunami affected the whole length ofJapan from the northern tip Hokkaido to thesouthern tip Okinawa; it reached 6 m in thearea of greatest height and 3~4 m in mostother areas. Accordingly, the effects of thetsunami were easily contained by the structures. The Act on Special Measures for the
Chile Tsunami clearly indicated that“tsunami-prevention-measures were to be
newly installed and tsunami-prevention
structures to be improved.” As a result of
this, the giant tsunami breakwaters in Ofunato and other structures of similar scale
were constructed. In addition, the international tsunami warning system was completed.
In those days, however, people were notwithout doubt regarding tsunami-prevention
structures. Symbolic of this mistrust was thecaption to some photos in the Sanriku Tsunami Report published in commemorationof the 1960 Chile Tsunami (by the Sanriku
Area Survey Committee). The caption reads,“Do people control nature? Or, does naturelaugh at people?” However, soon after
completion of the new tsunami-prevention
structures, a tsunami resulting from the1986 Tokachi-Oki Earthquake struck the
Sanriku area. Because the height of thistsunami was no higher than that of the 1960
Chile Tsunami, its effect was almost completely blocked.
In this way, it became clear that naturalforces of limited power could be controlled
by means of man-made structures, and this,in turn, promoted the concept that theeffects of not only tsunamis but even flooding could be controlled by the use of manmade structures. Of course, although structures can control natural forces, there is alimit to their capacity to do so. The generation that built these structures learned theeffectiveness of tsunami-prevention structures by seeing them actually protect against
external forces; but they then forgot the factthat such structures inevitably reach theirlimit in terms of preventive capacity. The

next generation felt certain from the outsetthat natural external forces could be controlled by the use of structures. Then, they
forgot the necessity of preparing for the
worst. Representative of this attitude is a
recent review and prioritization of government programs that concluded, “Embankments to protect Tokyo from flooding that
may occur only once in 200 years areunnecessary.”
The 2011 off the Pacific coast of
Tohoku Earthquake

On March 11, 2011, a giant earthquake
occurred off the Pacific coast of Tohoku
Area. The Japan Meteorological Agency
was unable to accurately predict the earthquake. According to the seismo-techtonics,
which was based on 30 years of observation,
each of three blocks involved would moveindependently; whereas, in the current earthquake, the three blocks moved simultaneously. If five billion years have passed since
the birth of the Earth and if the lifespan of
human beings is set at 50 years, 30 years ofgeological observation is equivalent to a
10-second checkup for humans. The error in
the seismo-techtonics seems to be attributable to the assumption that everything could
be understood through only 30 years ofobservation. This error will be corrected
through continued observations over threeor four hundred years and through in-depth
studies of past tsunamis.
How to Prevent or Mitigate Tsunami
DamageIn 1983, “Guidelines for Disaster-prevention
Measures in Areas Constantly Threatenedby Tsunamis” (draft) was prepared jointly
by the River Bureau, the Ministry of Construction, and the Fisheries Agency. In 1998,‘“Guidelines to Strengthen Tsunami Countermeasures in Local Disaster-prevention
Plans” was prepared with the consent of
seven tsunami-related government agencies.
Both sets of guidelines clearly state thathuge tsunamis cannot be prevented byman-made structures, that human lives
should be protected by means of a disasterprevention system, and that disasters should
be controlled by building towns that arehighly resistant to tsunamis. Accordingly, it
was already anticipated that in a hugetsunami such as the one produced by theonce-in-a-millennium great one like the2011 earthquake, the tsunami would overflow or destroy all tsunami-prevention
structures.
In this tsunami, there are many examples“Do people control nature?
Or, does nature laugh at people?”A page of Sanriku Tsunami Report published incommemoration of the 1960 Chile tsunami: At
Naka-Akasaki in the Sanriku area, new building
plans were withheld in anticipation of constructionof new tsunami-prevention facility.

in which excessive reliance on disasterprevention structures and on contemporary
information led to suffering. For example,
although a part of the Kirikiri area ofOzuchi Town in Iwate Prefecture is locatedoutside the tsunami inundation area
assumed by the prefecture and in spite of
having been moved to high ground in 1933,
the death rate there was the highest in the
Kirikiri area. In Toni-Hongo of Kamaishi
City in Iwate Prefecture, a grandmother,
who had experienced the 1933 Showa Sanriku Tsunami and lived on high ground,sought refuge on an even higher ground justafter the earthquake hit. Her daughter, who
also lived on high ground, similarly took
quick refuge because they had agreed
between them to seek safety whenever anearthquake occurred. The older woman’s
40-year old grandson, who lived in a lowlying area, was caught off guard by the tsunami because he believed that the highanti-tsunami embankment would protect
him. After seeing the tsunami overtop theembankment, he sped off for safety in his
car but was still caught by the tsunami
wave.
The tsunami-prevention structures currently in use are fully capable of protecting
against tsunamis that might occur once several tens of years, or one-hundred and several tens of years. But studies are underway
regarding the need for structures that could
reliably demonstrate damage control against
a tsunami strike of even greater magnitude.
Anyway, human lives cannot be fully
protected merely by the use of man-madestructures. It is more important for us “tolive on high ground, to judge a situation
with our own eyes, and to seek safety at ourown initiative.” Only then can we put ourselves in a position to mitigate the effect ofnatural disasters. This basic concept will
never change.

August 2012 Steel Construction Today & Tomorrow 2

The 2011 Great East Japan Earthquake

Coastal Facilities: Lessons Learned fromthe Quake and Tsunamis
by Takahiro Sugano, Port and Airport Research Instituteteam as they investigated coastal structures
along approximately 600 km of coastline, thefollow-up experiments and analyses. A characteristic feature of the ground motion
observed is the long duration and highfrequency component, as shown in Fig. 1.
For the reason, the degree of damage ofcoastal facilities by the ground motion was
rather small. This broad coverage of investigation thus far made facilitated the interpretation of damage patterns across the entire
region affected by the earthquake, by distinguishing coastal structure damages due tostrong ground shaking and secondary effects(i.e., liquefaction, ground failures, settlement)
caused by subsequent, significant tsunami
inundation.

Introduction

On March 11, 2011, the largest earthquake
ever recorded in Japan struck the coast of the
Tohoku region of Japan, which was named as
the “2011 off the Pacific coast of Tohoku
earthquake” by the Japan Meteorological
Agency. The Mw=9.0 earthquake generated
strong motions that affected the Honshu
island from Tokyo Bay to the northern extent
of the island, and induced a series of tsunamis that devastated coastal communities
throughout the region. Significant aftershocks (Mw>7) were experienced that further
contributed to damage in the Tohoku coastal
region during emergency response and recovery efforts.
This report summarizes the findings of thePort and Airport Research Institute researchAcc. (Gal)Fig. 1 Comparison of Acceleration Time History and Fourier Spectrum between
the Port Island (1995 Hyogoken-Nambu Earthquake) and the Sendai Port
(2011 Earthquake)
200
0
-200
-400
-600

Sendai Port N-S Max. 623.7 Gal
0

50

100

150

Time (s)

1000

8
6

0.3 Hz200

1.0 Hz4

Fourier spectrum (Gal*s)

2

100

8
6
4
2

10

8
6

Port Island (1995)

4

Sendai Port (2011)

2

1
0.1

2

4

6 8

1

2

Frequency (Hz)3 Steel Construction Today & Tomorrow August 2012

4

6 8

10

Damage to Coastal Structures

In many cases, the condition of structures
examined at the time of our investigation
was the combination effect of earthquake
and tsunami, and the determination of thesequence of damage and relative influenceof seismic and tsunami loading was not possible in the field. These suppositions are
based on the collective engineering judgment, tempered by first-hand experience at
coastal structures along with earthquakes
worldwide and considerable effort for analyses of case studies (like “criminal” investigations) of many of similar events. Many of
the interpretations of failure modes provided
in this report are opinions that will be
refined with time as more data becomes
available at the key sites. The findings andrecommendations provided in this initialreport are intended to imitate discussions
within the port engineering community,
foster applied research efforts, and ultimately lead to enhanced knowledge and bestpractices.
In this report, I would like to discusswith a typical damage due to combination
effect of earthquake motion and tsunami andexpress my opinion about the future outlookof design concept by considering both seismic and tsunami effect.
A notable feature of damage caused byground motion is the issue of quay wall seaward deformation and subsidence of theground behind the quay wall. The seaward
deformation of quay wall, which is small
compared with the central part of theamount of displacement of the quay edge,
often shows a gradual arc as shown in Photo
1. Amount of ground subsidence just behindthe quay wall tends to grow harmoniouslywith the amount of seaward displacement.
Accordingly, a whole berth often becomes
unusable.
Now, consideration is made on thedamage to the steel sheet pile quay wall in
Soma Port during the 2011 off the Pacificcoast of Tohoku Earthquake, shown in Photo
2. It is reasonable that the damage of quay
wall occurred as a result of the action ofground motion and subsequent tsunami.
However, in the post-disaster field investi-

gations, there are many traces of the damage
caused by the ground motion that cannot be
separated by the action of the tsunami.
Accordingly, from the difference between
damage caused by ground motion andcaused by tsunami, the cause of damage will
be pursued. The difference between Photos
1 and 2 is that, while almost the same
degree of damage occurred in both quay
walls, the entire damage occurred in thequay wall in Photo 1. On the other hand, in
Soma port, damage occurred only to thecorner and about 30 m part of entire quay
wall, but other parts are quite healthy (Photo3). The detail of the failure process at thatmoment is not known. I plan to carry out
efforts to clear the failure process by experiments and numerical analyses.

Photo 1 Damage to the steel sheet pile quay wall of Hakodate Port during
the 1993 Hokkaido-Nansei-Oki Earthquake

Idea of New Design Concept that Considers
the Effects of Both Earthquake and Tsunami

Photo 2 Damage to the steel sheet pile quay wall of Soma Port during
the 2011 Off the Pacific coast of Tohoku Earthquake

Photo 3 Damage to the steel sheet pile quay wall edge portion in Soma Portduring the 2011 Off the Pacific coast of Tohoku Earthquake

The design standard for port facilities inJapan went through a major revision in2007. The most remarkable feature of the
new design standard is that it is completely
based on the idea of “performance-based
design methodology.” At the same time, the
new standard is designed to be consistent
with recent advances in the field of engineering seismology and earthquake engineering. According to the current design
standard, it is better to investigate andevaluate the damages by considering boththe earthquake motion and the tsunami wave
loading during the 2011 off the Pacific coastof Tohoku Earthquake so as to improve thecurrent design standard.
The idea of “performance-based design
methodology” constitutes the backbone of
the new design standard. The ‘objective of
the facility’ is at the top of the design process. Then, the ‘performance requirements’are specified in the “ministerial ordinance”
in a plain language to achieve the objectiveof the facility so that the objective can beunderstood by taxpayers. Thirdly, the ‘performance criteria’ are defined to achieve theperformance requirements, using technicalterms so that these criteria can be strictlyinterpreted by engineers. Finally, the performance of the facility is verified by some‘verification method.’
From the geotechnical point of view, if
we think a time-series facility damage
caused by the earthquake and tsunami, thedamages that will occur can be summarized
as follows:

August 2012 Steel Construction Today & Tomorrow 4a) High response acceleration, large deformation, material degradation such asliquefaction, and growth of cracks that
occurb) Tsunami wave force, hydraulic force offlow such as drag force, buoyancy,
impact of floating objects during tsunami
attack. Especially, during a seaward
tsunami, destabilization of the pore waterpressure in the ground may occur, likethe quick drawdown phenomenon, as
shown in Fig. 2 (lower figure)At present, the cause of damage and thetsunami-affected actual damage mechanism
have not yet been clarified. We are promoting experimental and numerical research inorder to clarify the mechanism of damage
caused by the combined action of the earthquake and tsunami.
To establish the new design concept forcoastal structures with “tenacious design”
against the combined action of earthquakes
and tsunamis, loading conditions, performance requirements, performance criteria
and verification method are specified. The
loading conditions are summarized asshown in Table 1, and it is required to set
the appropriate combination of loading conditions. In the case of tenacious breakwater,
we refer the performance requirements
listed in Table 1. In case of the largest
tsunami, it is difficult to interpret the performance requirements such as “serviceable”
and “repairable” into the performance criteria, and at the present state it is also difficult
to verify the design with quantitative accuracy.
At the moment, we can “design” in thecase of the tsunami that occurs mostfrequently. On the other hand, in the largest
tsunami case, we propose just “design concept.” After learning the lessons from the1995 Hyogoken-Nambu earthquake, theconcept of the Level 1 and Level 2 earthquake motions was introduced, and thesettlement of the idea of the seismic design
with two-level ground motions took several
years. Similarly, it may take few years tosettle the new design concept against the
combined actions of earthquake and tsunami
with consensus among the stakeholders suchas designers, construction officials, administrators and so on.

5 Steel Construction Today & Tomorrow August 2012

Fig. 2 Assumed Destruction Mechanism of Breakwater
Landward tsunami
Tsunami flow

CaissonHydraulic force
Duration of overflow >Amount of excavation

Permeable pressure
Excess pore water pressure
Replaced sand

Quick dropdown in water level

SeabedSeaward tsunami
Caisson

Permeable pressure
Excess pore water pressure

Instability of the replaced sanddue to the rise up ofexcess pore water pressure

Replaced sandSeabedTable 1 Design Concept for Coastal Structures as “Tenacious Design” against
Combined Actions of Earthquakes and Tsunamis
Action (load)

Definition

Objective of the facility(performance requirements)

Level 1 groundmotion(valuable action)

The ground motion
with high probability ofoccurrence at the site
during the design
working life.

Minor or no damage/little
or no loss of serviceability (serviceable)

Level 2 groundmotion(accidental action)

The largest groundmotion among groundmotions at the sitefrom scenario earthquakes

Damage control/shortterm loss of serviceability (repairable)

Ground motion
with the tsunami
source(accidental action)

The ground motion
sources generate
tsunamiTo consider in conjunction with the tsunami

Tsunami that
occurs mostfrequently(accidental action)

To consider the scale ofthe tsunami from socioeconomical point of viewof facilities and service
period, which occurs
once in ten years to ahundred yearsa)Protection of humanlife and propertyb)To support socioeconomic activity(serviceable)

Multi-faceted concept byconsidering the facilities
such as revetment andembankment, and thenon-structural measures

Largest tsunami(accidental action)

Scale of tsunami that
occurs at the site at afrequency of about
once a thousand
years to roughly a few
hundred yearsa)Protection of human lifeb)Mitigation of eco
nomic lossesc)Secondary disasterpreventiond)Prompt recovery of
the facilities

Multi-faceted concept byconsidering the facilities
such as revetment andembankment, and nonstructural measures

Remarks

The 2011 Great East Japan Earthquake

Damage to River Levees and Measuresfor Restoration and Reconstruction
by Ikuo Towhata, Professor, Department of Civil Engineering, The University of Tokyo
Introduction

The conventional philosophy of seismic
design of river levees in Japan used to be
based upon the concept of factor of safety
greater than unity, being similar to the designof other structures. However, there have been
two important factors to be considered inriver levees. The first is the financial issue
that the budget available for seismic retrofitting per unit length of levees is limited
because the entire length of seismically vulnerable levee is substantial. The second is thatthe occurrence of the seismic factor of safety
less than unity does not mean an immediate
disaster or overtopping of water because theprobability of the simultaneous occurrence ofa strong earthquake and significant flooding
has been considered low. Consequently, seismic factor of safety greater than unity has notbeen compulsory.
Alternatively, it has been aimed to restore
possible damage of river levees within a shortperiod of time that is typically 14 days. To
achieve this goal, it is essential to introduce theprinciple of seismic performance-based designin which the possible distortion of a levee isassessed under a given design earthquake,compare it with the allowable distortion, and,if the assessed one exceeds the allowable limit,
examine the effect of any mitigation measure.
In this view point, the present short article
addresses what river levees experienced
during the 2011 Great East Japan Earthquakeand successful cases of damage mitigation.

Fig. 1 Locations of Levee Damage ofInterest

Naruse River
Sendai City
Hinuma LakeTokyo

levees consists of subsidence at the crest andlateral spreading, which is a typical nature ofliquefaction-induced deformation of an embankment, those damage shown in Photo 2 isinferred to have been caused by liquefaction
inside levee bodies. The mechanism of thisnew idea is considered to be as what follows
as studied by Sasaki et al. (1994) 1 ) and
Kaneko et al. (1996)2) on previous cases ofTokachi and Kushiro Rivers in 1993 (Fig. 2):

Sawara on Tone River

1) A river levee sinks into soft clayey subsoil
because of consolidation,2) The sunken part has poor drainage of infiltrated rain water and seeping ground water
because the elevation is lower than the
ground surface, and the surrounding soil isless pervious clay, and
3) The procedure of subsidence and consequent lateral expansion is possibly accompanied by loosening of soil and reducedliquefaction resistance.
The problems related with the internalliquefaction are such as difficulties in detecting a liquefaction-prone levee and drainage ofwater from this type of a levee.

Seismic Damage of River Levees in 2011

Figure 1 shows the location of rivers andlevees to be discussed in this article. First, thelevee of the Tone River at Sawara (Photo 1)
demonstrates a typical damage of levee or
embankment resting on liquefied subsoil;
subsidence at the top and longitudinal cracks
caused by lateral spreading. As is often thecase, this site used to be a part of a river
channel, and was filled with sandy soil artificially or naturally, forming a liquefactionprone subsoil condition.
A noteworthy case was such as in Photo 2
in which a heavy distortion occurred in spiteof the clayey and hence unliquefiable subsoil.
Because the induced deformation of such

Fig. 2 Schematic Illustration of Mechanism of Liquefaction inside a Levee
Original shape of levee

Consolidationand settlement

Subsidence

Loosened
Unliquefiable cohesive soft soil

August 2012 Steel Construction Today & Tomorrow 6

Photo 1 Significant distortion of levee of Tone River in Sawara

Successful Mitigation of Liquefactioninduced Damage of Levees

Because of the high concerns for seismic
safety of levees in the past decade, mitigation measures have been executed. The
Great East Japan Earthquake in 2011 offereda good opportunity to validate their effects.
Note that the mitigation measures were
designed against Level-1 design earthquakes
for which the recurrence period is about 50
to 70 years. Although installation of gravel
drains was successful at Omigawa of Tone
River, while sand compaction pile was
effective at the Shimo-Nakanome of NaruseRiver (Fig. 1), the page limitation does notallow detailed remarks here; refer to Towhata (2012)3).

Photo 2 Significant distortion of the Hinuma levee

At Sakae of Ibaraki, the Tone River levee
had been reinforced by underground sheet
pile walls (for reducing seepage of water)
accompanied by a wide berm on the riverside. During the earthquake, no distortion
occurred on the river side (Photo 3). In contrast, the land side of the levee distorted due
to liquefaction in the foundation soil inwhich the ground water level is within 50
cm from the surface (the author’s observation in April, 2012). The damaged section
was restored by installing 8-m sheet piles
along the slope toe (Photo 4). The holes inthe sheet pile allow seepage of ground water
so that the water level in the levee would belowered during high water level in the river.

Numerical Analyses

The author proposed a viscous modeling ofliquefied sand for performance (deformation)assessment of structures subject to strong
shaking (Towhata et al., 1999 and 2010)4),5)
and developed a numerical program. Fig. 3
is a levee model for an example analysis, ofwhich the performance (settlement at crest)is mitigated by embedded sheet pile walls,
counter-weight berms, or both (Fig. 4).
Results of a flow analysis as shown in Fig. 5
demonstrate that a combination of a sheet
pile wall and a counter-weight berm canreduce the crest subsidence to less than 50%
after strong shaking and soil flow of 20 seconds.

Hole in asheet pile

Photo 3 River side of Tone River levee at Sakae without damage(entire restoration of the levee going on in April, 2012)

7 Steel Construction Today & Tomorrow August 2012

Photo 4 Reconstruction of land side of Tone River levee at Sakae
by installing sheet pile walls with holesFig. 3 Levee Model subject to Liquefaction in Foundation
for Performance Analysis

5m

10 m

Symmetric model ofembankment restingon liquefied subsoil

5m

X

Fig. 4 Sheet-pile Walls and Counter-weight Berm as
Mitigation Measures

Berm :
2m

E=10000 kPa

50 m

10 m

γ=16 kN/㎥

1m

Boundary with zerolateral displacement

50 m
10 m of liquefied sand10 m

γ=20 kN/㎥

Sheet pile walls
Viscosity coefficient=2700 kPa. second

El=126,000 kN㎡
per1-meter width
Base layer

BaseFig. 5 Mitigation of Subsidence of Levee Undergoing Liquefaction in Foundation
ISOPE2 subsidence history fig.

0.0
0.2

Berm and Type 5 sheet pile

Subsidence at crest (m)

0.4
0.6

Type 5 sheet pile

0.8

10 m berm

1.0
1.2

No mitigation
0

5

10

15

20

5

Time (seconds)

Conclusions

This article concerns the seismic damage oflevees during the 2011 Great East Japan
Earthquake. Among many damages, thepossibility of liquefaction inside a levee is a
new important issue. In contrast, several
mitigation measures worked successfullyand embedded sheet pile wall is among
them. Finally, the performance assessmentof levees subject to liquefaction is very possible by using a viscous liquid model.

References

1) Kaneko, M., Sasaki, Y., Nishioka, J.,
Nagase, M., and Mamiya, K. (1996)
River dike failure in Japan by earthquake
in 1993, Proc. 3rd Int. Conf. on Recent
Advances in Geotechnical Earthquake
Engineering and Soil Dynamics, pp.
495-498.
2) Sasaki, Y., Oshiki, H., and Nishikawa, J.
(1994) Embankment failure caused by
the Kushiro-Oki earthquake of January
15, 1993, Session publication during the13th ICSMGE, Delhi, pp. 61-68.
3) Towhata, I. (2012) Seismic performanceof river levees; experience and prediction, 2nd Int. Conf. on Performancebased design in earthquake geotechnicalengineering, Taormina, Italy.
4) Towhata, I., Orense, R. P. and Toyota, H.
(1999) Mathematical principles in prediction of lateral ground displacement
induced by seismic liquefaction, Soils
and Foundations, Vol.39, No.2, pp.1-19.
5) Towhata, I., Trinh Thi Lan Anh , Yamada,S., Motamed, R., and Kobayashi, Y.
(2010) Zero-gravity triaxial shear tests onmechanical properties of liquefied sandand performance assessment of mitigations against large ground deformation,
5th Int. Conf. Recent Advances in Geotechnical Earthquake Engineering andSoil Dynamics, San Diego.

August 2012 Steel Construction Today & Tomorrow 8

The 2011 Great East Japan Earthquake

Liquefaction-induced Damage toHouses and Buried Lifelines

by Susumu Yasuda, Professor, and Keisuke Ishikawa, Assistant, Dept. of Civil andEnvironmental Engineering, Tokyo Denki University

The 2011 Great East Japan Earthquake, with amagnitude of Mw=9.0 occurred in the Pacific
Ocean about 130 km off the northeast coast ofJapan’s main island on March 11, 2011. Liquefaction occurred in a wide area of reclaimed
land along Tokyo Bay, though the epicentral
distance was very large, about 380 to 400 km.
Much land has been reclaimed in the Tokyo
Bay area since the seventeenth century. Liquefaction has been induced during past earthquakes, such as 1923 Kanto Earthquake and1987 Chibaken-toho-oki Earthquake. However, the Great East Japan Earthquake is thefirst on record to cause liquefaction in such awide area and to severely damage houses, lifelines and roads.

Fig. 2 Liquefied Area from Odaiba in Tokyo to Chiba City

Investigation of Liquefied Sites

houses, river dikes, roads, lifelines and ports
and harbors were serious, Kanto Regional
Development Bureau of the Ministry of Land,
Infrastructure, Transport and Tourism intended
to make joint research with JGS to identify
liquefied sites. Fig. 2 is the map of liquefied
zones thus estimated, which is slightly modified from the tentative map.

The authors started to investigate Tokyo Bay
area on the next day from the earthquake
because all trains in Tokyo Bay area stopped
service immediately after the earthquake until
the midnight of the day. In the investigation,
the roads where boiled sands were observed
and not observed were marked on maps (Fig.
1).The zones surrounded by red lines were
judged to be liquefied, but note is necessarythat some small districts in the zones did notliquefy because their grounds had been
improved by sand compaction method or othermethods mentioned later. Thus about ten days
were necessary to investigate the whole areafrom Odaiba in Tokyo to Chiba City throughUrayasu, Ichikawa and Narashino Cities. A
tentative map of liquefied zones was drawn
based on this first stage investigation (Yasuda
and Harada, 2011).
As the liquefaction-induced damages toFig. 1 Method to Judge Liquefied andNon-liquefied Zone

(Yasuda et al., 2011)
9 Steel Construction Today & Tomorrow August 2012

Narashino(Joint research by Kanto Regional Development Bureau of the Ministry of Land,
Infrastructure, Transport and Tourism and JGS)

Soil Condition in Liquefied Area

As demonstrated in Fig. 2, severely liquefied
area by the earthquake was from Shinkiba inTokyo to Chiba City through Urayasu, Ichikawa, Funabashi and Narashino Cities in
Chiba Prefecture. The reclaimed lands in thisarea were constructed after 1966. In the reclamation work, dredged soils were filled fromthe bottom of sea to the height of about sea
level. Then the filled surface was covered withhill sands. Fig. 3 draws the process of thedredging work. The soils of sea bottom wereexcavated by a cutter, exhausted with water by
Fig. 3 Process of Dredging Worka pump, transported by a convey pipe, thendischarged from the exit of the pipe. As thedredged soils contain much water, coarse soil
grains and fine soil grains, they are apt todeposit near the exit and far from the exit,
respectively. Moreover the position of the exit
moves to various positions, resulting in very
non-homogeneous strata. After filling with thedredged soils and covered by the hill sands, nosoil improvement works were treated except
several special areas where sand compaction
piles or gravel drain piles and other methods
were applied to prevent liquefaction.
As three sets of data base had been published by JGS, Chiba Prefecture and Tokyo
Metropolitan Government in the liquefied area,
the authors estimated brief soil cross sections
along 11 lines which are perpendicular to theshore lines based on these data. Fig. 4 illustrates the estimated soil cross sections along aline in Urayasu 3-3’ together with the zones
where sand boils were observed. The zones
where sand boils were observed are exactly
coincided with the area of reclaimed landFig. 4 Estimated Brief Soil Cross Sections

which is the sea side from old sea wall. In thereclaimed zone, a filled layer with mainly hillsand (B) and a filled layer by dredged sandy
soil (F) with low SPT N-values of 2 to 8 aredeposited with a thickness of 6 to 9 m. An alluvial sand layer (AS) with SPT N-values of 10
to 20 underlay with a thickness of 4 to 8 m. A
very soft alluvial clay layer (AC) is depositedunder the AS layer with a thickness of 10 to 40
m, by increasing the thickness towards sea.
Diluvial dense sandy layer (DS ) with SPT
N-value of more than 50 underlay. Water tableis shallow as GL −0.5 m to −3 m, by decreasing the depth towards sea. On the contrary, inthe zone where sand boil was not observed, AS
layer deposited from ground surface. Therefore
it can be estimated that the AS layer basicallydid not liquefy by the 2011 Great East Japan
Earthquake though some loose part mightliquefy in the reclaimed land, and that somepart of the dredged sandy soil under watertable might liquefy. Composition of soil layers
is similar in other 10 soil cross sections, thoughthickness of eachlayer is different.
A technical committee organized by
Urayasu City Government and chairedby Prof. K. Ishihara
carried out detailed
soil investigations in
Summer by boring,S P T, C P T, P S
logging, undisturbed sampling,
cyclic triaxial tests
and others, and reported valuable data in
December 2011. Frequency distributions ofnormalized SPT N-values, N1 and fines content, FC of the F layer and the AS layer are compared in Fig. 5 (1) to (4). Fines content of the Flayer are very scattered and greater than thefines content of the AS layer, though the F layer
was essentially taken from the AS layer. Thisdifference must be attributed to the lack of the
alluvial sandy soils for the reclamation work.
As the dredged zones were located just the topof a delta formed by Edo River, sandy soils
were not enough for the filling, then some alluvial clays had to be excavated and mixed withthe alluvial sandy soils. Average value of thefines content of the F layer is extremely high as
43.8 %. However, plasticity indexes, IP, are nothigh though their fines content are large. N1 of
the F layer is apparently lower than that of the
AS layer. Undisturbed samples were taken atnine sites to obtain cyclic shear strength andshear modulus. Frequency distributions ofshear stress ratio to cause liquefaction in 20

Fig. 5 Frequency Distributions of N1 and Fc for Dredged Soils and Alluvial Sands(Quoted from the research material by the Technical Committee organized by Urayasu City)

cycles tested by cyclic triaxial tests, RL (NL=20,
DA=5%) for the F and the AS layers, are shownin Fig. 6. Dominant RL values for the F layer
and the AS layer are 0.25 to 0.30 and 0.30 to
0.40 respectively though the data are very scattered in the F layer. Therefore it can be said thesoils in the F layer are more liquefiable thanthose in the AS layer.
Fig. 6 Frequency Distributions of Shear
Stress Ratio to Cause Liquefaction

Process of Liquefaction

As the earthquake occurred at 14:46 in theafternoon on Friday, many important photos
and movies were taken at many sites along
Tokyo Bay to study the process and mechanism of liquefaction. Among them a series ofphotos taken by Mr. Katsunori Ogawa justafter the earthquake at Maihama 3-chome in
Urayasu City is introduced in Photos 1 (A~D):<<< Shake due to main shock started at 14:47
in Urayasu>>>
A <14:56>: Spew out of muddy water started
in northeast direction. It took several minutes
to start the boiling after the settlement of themain shock.
B <15:01>: Boiled muddy water gradually
spread and covered the road.
<<<A strong aftershock hit Urayasu at
15:16>>>
C <15:21>: The southwest road was covered
completely with muddy water. Water pipes
look like to break.
D <15:22>: Many houses settled and tilted andcars submerged in the boiled muddy water.
The authors sent out questionnaires to about
August 2012 Steel Construction Today & Tomorrow 10

30 inhabitants in Irifune district which is also
located in Urayasu City to ask the timing of
boiling and height of boiled muddy water.
Answers are summarized in Fig. 7. About 1/3
persons observed the boiling of muddy water
immediately after the main shock, howeveranother 1/3 persons recognized the spout of
muddy water 5 to 9 minutes after the main
shock. Other persons found the muddy waterat different timing. Height of the muddy water
was not high as mainly less than 9 cm after themain shock. About 2/3 persons mentioned thatthe boiling of muddy water continued up to
the aftershock, and about 3/4 persons watchedcovered water until aftershock. On the contrary, about 3/4 persons observed spew out of
muddy water just after the aftershock and the

Photo 1 Sequential photos taken
by Mr. K. Ogawa
11 Steel Construction Today & Tomorrow August 2012height of the water Fig. 7 Questionnaires to Inhabitants in Irifune
was apparently
greater than theheight after themain shock. Thismeans the boilingaccelerated due tothe aftershock andmore severe liquefaction occurred
during aftershock
at some sites.
Question on thetiming of the settlement of houses
must be difficult toanswer for inhabitants, however, a
1/3 persons andanother 1/3 persons
answered that thesettlement of theirhouses was zeroand 10 to 19 cm
respectively after the main shock. And, manytime; 14:46:16 at Inage and 14:46:15 at
inhabitants recognized the settlement on the
Urayasu. In Urayasu’s wave, frequency did notnext day.
change drastically after the peak acceleration
According to the hearing in Imagawa
which induced at about 118 sec. (14:48:13).
district, some inhabitants testified boiling did
On the contrary frequency changed to low
not occur during main shock but occurred
value after two peaks at 120 sec. (14:48:16)
during aftershock.
and 126 sec. (14:48:22). Therefore it can be
judged liquefaction occurred at around14:48:16 to 14:48:22 at K-NET Inage. This
Effect of Long Duration of Shaking
on Liquefactionmeans many cycles of shear stress, say around20 cycles from 110 sec., might cause liquefacFig. 8 shows ground surface accelerations
during the main shock and the aftershock. Sur- tion at K-NET Inage site. And it must be notedshaking still continued for long time after theface accelerations were not high as around 160
occurrence of liquefaction. By referring to the
cm/s2 to 230 cm/s2 though severe liquefaction
accelerograph at K-NET Urayasu, shake of theoccurred. The accelerograph, recorded at
ground at Inage continued for about 3 minutes
K-NET Inage in Chiba where actually boiled
after liquefied.
sand was observed, is very important because
One more impact to the ground must be theliquefied time can be judged from the recorded
waves. Fig. 9 shows the accelerograph at Inage shaking during the aftershock. Peak accelerations during the aftershock were almost a half
together with that at K-NET Urayasu which
was recorded on the ground where liquefaction of those during the main shock in Tokyo Bay
did not occur. Both records started almost same area as shown in Fig. 8. Even though, as mentioned above, boilingFig. 8 Comparison of Accelerations during Main andoccurred after theAftershocks by K-NET
aftershock at somesite. Therefore, major
reason of the severeliquefaction must be
the effect of long
duration of shaking
during main shock
and an aftershock.
The authors tried
to conduct cyclic
torsional shear tests

Fig. 9 Comparison of Accelerographs Recorded at K-NETand some simple
Inage and Urayasu
analyses to evaluate
the effect of the long
shaking on the occurrence of liquefaction.
Two types of shear
wave were applied to
specimen, sine waveof 20 cycles andthe seismic wave
recorded during main
shock and aftershock
at Urayasu K-NET. In
case of seismic wave,
excess pore waterpressure increased
gradually with shear
stress as illustrated inFig. 10. Then, relationships between stress ratio R (τd/σ’) for sine Fig. 10 Time Histories of Shear Stress,
wave or Rmax (τmax/σ’) for seismic wave andShear Strain and Excess Pore
residual excess pore water pressure u/σc’ are
Water Pressure
plotted in Fig. 11. As R=0.27 for u/σc’=1.0 and
Rmax=0.31 for u/σc’=1.0, the correction factor
Cw by JRA standard (2002) becomes 0.82.
Then safety factor against liquefaction FL andliquefaction potential PL were evaluated forevery boring data used for the estimation of 11
brief soil cross section, under the conditions of
Cw=0.82 and 1.0. In the estimation, RL wasestimated from SPT N-values and FC, by using
the proposed formula by the technical committee of Urayasu City. Fig. 12 shows evaluatedFL values for a boring data in Urayasu whereliquefaction occurred. If the Cw is assumed as
1.0, all FL are estimated greater than 1.0
whereas FL are less than if Cw is assumed as
0.82. Fig. 13 compares PL for all boring data
under the assumption of Cw=0.82 and Cw=1.0.
If Cw=0.82, PL for liquefied sites are calculated
as greater than about 10 and severity of liquefaction can be demonstrated.
Fig. 12 Analyzed FL at Imagawa
in Urayasu City

Fig. 11 Relationship between Shear
Stress Ratio and Excess Pore
Water Pressure

Fig. 13 Effect of CW on PL

Settlement and Tilting of Houses

According to the result of totaling by the Ministry of Land, Infrastructure, Transport andTourism, about 27,000 houses were damaged
due to liquefaction (Table 1). Photos 2 (1~2)
show a damaged house taken from outside andinside respectively. The house settled andtilted about 40/1,000. In the heavily tilted
houses, inhabitants feel giddy and nausea anddifficult to live in their houses after the earthquake. However damaged houses due to liquefaction had been judged as partial collapse or
injured only during past earthquakes becauseof no damage to walls and windows, though it
has been desired both settlement and inclination must be considered in the judge.
Then, in May, Japanese Cabinet announced

Table 1 Number of Damaged
Houses due to Liquefaction
Prefecture

Number ofdamaged houses

Iwate

3

Miyagi

140

Fukushima

1,043

Ibaraki

6,751

Gunma

1

Saitama

175

Chiba

18,674

Tokyo

56

Kanagawa

71

Total

26,914

Source: Ministry of Land, Infrastructure,
Transport and Tourism
August 2012 Steel Construction Today & Tomorrow 12

new evaluation standard for the damage ofhouses by the two factors, settlement and inclination, as shown in Table 2. Numbers of damaged houses in Urayasu City by the new standard are listed in Table 3 together with thenumbers counted by old judging method(Urayasu City, 2011). Numbers of completely
and partially destroyed houses increased drastically, and the numbers of damaged houses
more severe than partially destroyed enlarged
to 3,680.
As mentioned above, occurrence of liquefaction must be affected by the aftershock. Not
only the occurrence of liquefaction but also
the settlement and inclination must be affectedby the aftershock. Ground water table
increased after the main shock and boiled
muddy water covered the ground surface until
the aftershock at many sites. Then, settlementof houses is excitable during the aftershock
though shaking amplitude was less than thatduring the main shock as schematically shownin Fig 14.
Many inhabitants along Tokyo Bay arefacing to the serious problem, how to restore
the damaged houses. Complicated problem isthe re-liquefaction during aftershocks or futureearthquakes. Not only the restoration but also
some countermeasure against re-liquefaction
must be applied, but the problem is the cost
and the technique to treat the ground under
existing structures. Then early development on
effective and economic measures againstliquefaction for existing timber houses are
facilitating by several organizations. Moreover, applicability of special measures toimprove an area by decreasing ground watertable is being studied.
Table 2 New Evaluation Standard forDamage of Houses
Grade ofdamageEvaluation method
Inclination Settlement

Completely
destroyedMore than
1/20

Floor to 1m
upper thanfloor

Large-scalepartially
destroyed

1/60 to
1/20

25 cm
upper thanfooting tofloor

Partially
destroyed

1/100 to
1/60

Up to 25 cm
upper thanfooting

Table 3 Numbers of Damaged
Houses in Urayasu City by
Old and New Standards(Urayasu City)
Number of houses
Grade of damage

Old
standard

New
standard

Completely
destroyed

818

Large-scalepartially destroyed

0

1,541

Partially destroyed

33

2,121

Partially injured

7,930

5,096

No damage

1,028

1,105

Total

8,999

9,981

boundaries due to a kind of sloshing of liquefied
ground as schematically shown in Fig. 15 (1),because shaking continued for long time after
the occurrence of liquefaction. Fig. 16 shows
heaved footways or alleys in Urayasu City
together with contour lines of the thickness ofthe F layer under the ground water table. It may
be said that the heaving occurred at the sites
where the bottoms of the F layer, in other wordliquefied layer, are sloped. This implies that akind of horizontal buckling of surface layer
might occur due to the concentration of horizontal compressive stress as schematicallyshown in Fig. 15 (2). However, more studies arenecessary on the mechanism of the buckling.
In sewage facilities, pipes meandered orwere broken, joints were pulled out and pipes
were filled with muddy water. Many manholes
were sheared in horizontal direction and filledwith muddy water whereas few manholes
uplifted. Though the mechanism of these uniquedamages is still being studied, one author’s idea
is illustrated in Fig. 17. As mentioned above, akind of sloshing of liquefied ground mightoccur due to long duration of shaking andcaused thrust of roads. By the same movementof the ground, pipes might meander violently inhorizontal direction, resulting in pull out or
break of joints, and eventually liquefied muddy
water invaded into the pipes. Manholes might
be sheared due to horizontal force and pressurized liquefied muddy water came into the manholes. Fortunately or unfortunately invaded
muddy water into the sewage pipes and manholes might prevent uplift.

Fig. 14 Possible Effect of Aftershock on
the Settlement of House(1) Outside of the tilted house
Photo 3 Heaving of a footway at Takahama,Ichikawa City

Damage of Sewage and Manholes due to
Sloshing of Liquefied Ground(2) Inside of the tilted house
Photo 2 Severely settled and tilted house in
Urayasu City
13 Steel Construction Today & Tomorrow August 2012

Miracle phenomena, heaving, buckling or
thrust, were observed at several footways andalleys as shown in Photo 3 at many sites inTokyo Bay area. Some thrust might occur at the

Photo 4 Thick boiled soil observed in Chiba City

Fig. 15 Two Possible Mechanism of
Heaving
Horizontal
buckling

Wall

A kind of sloshing

Fig. 16 Heaved Footways or Alleys in Urayasu City together with Contour Linesof the Thickness of the F Layer under the Ground Water Table(Contour lines are quoted
from research materials (2011)

Liquefied layer

Horizontal
buckling

A kind of sloshing

Liquefied layer

Fig. 17 Unique Damage to Sewage
Manholes and Pipes

Traffic Problems due to Boiled Sand andSubsidence

Much eruption of sands and large ground subsidence occurred in the liquefied area. The
maximum thickness of the erupted sand and the
maximum ground subsidence observed by theauthors were about 30 cm and 50 cm respectively. This is the first experience for theauthors to see such thick deposited boiled sandin Japan. However, one of the authors had seen
similar much eruption and large subsidence inChristchurch during the main shock on September 2010 and aftershock on February 2011.
Fig. 18 compares grain size distribution curvesof erupted soils in Christchurch during the main
shock with those in Tokyo Bay during thisearthquake. Fines contents for Christchurch andTokyo Bay are similar. Then it is estimated thatin the very fine sands, ejection of water continues for long time because of low permeabilityof liquefied soils in both area. Moreover finesoil particles are easy to uplift above the groundsurface by the ejecting water. And the removalof the deposited soils by inhabitants accelerated
the settlement of the ground surface.
Photo 4 shows an alley covered by boiled
sands. It was difficult to run on the thick deposited wet sands by cars and bicycles. Moreoverlarge settlement of the ground around buildings
prevented to go out from parking spaces.
Conclusions

Severe liquefaction occurred by the 2011 Great
East Japan Earthquake in Tokyo Bay area.
Seismic intensities in the liquefied zones were
not high, though the liquefied ground was covered by boiled sands. The very long duration of
the main shock and an aftershock 29 minutes
later should have induced the severe liquefaction. Many houses settled substantially andtilted seriously due to liquefaction. Sewage
pipes meandered or were
Fig. 18 Comparison of Grain Size Distribution Curves ofbroken, joints were
Boiled Sands in Tokyo and Christchurch
extruded from the ground,and pipes were filled withmuddy water. Many manholes were sheared horizontally and filled withmuddy water, whereas
few manholes were
uplifted. This remarkabledamage to buried pipes
Tokyo Bay area
Tokyo Bay areaand manholes might haveoccurred due to a kind of
Christchurch
Christchurch
sloshing of liquefied
ground.

Acknowledgments

Some of the results cited in this text are quoted
from the report by the Technical Committee
on Measures against Liquefaction chaired by
Prof. K. Ishihara and organized by the
Urayasu City Government. Mr. K. Ogawa provided us important photos. The authors would
like to express their sincere appreciation tothem.
SourceYasuda, S. and Ishikawa, K.: Several featuresof liquefaction-induced damage to houses andburied lifelines during the 2011 Great East
Japan earthquake, Proc. of the International
Symposium on Engineering Lessons Learned
from the Giant Earthquake, Paper No. 46,
2012.
References

1) Japan Road Association (2002). “Specification for highway bridges” (in Japanese)2) National Research Institute for Earth Scienceand Disaster Prevention (NIED) “K-NET
WWW service.” Japan (http://www.knet.bosai.go.jp/)
3) Research material of the technical committee organized by Urayasu City Government.
http://www.city.urayasu.chiba.jp/menu1132
4.html (in Japanese)4 ) Ya s u d a , S . a n d H a r a d a . K . ( 2 0 11 )“Liquefaction-induced damage in thereclaimed lands along Tokyo Bay.” Geotechnical Engineering Magazine, JGS,
Vol.59, No.7, pp. 38-41, 2011 (in Japanese)5) Yasuda, S., Harada, K. and Ishikawa, K.
(2012). “Damage to structures in Chiba Prefecture during the 2011 Tohoku-Pacific
Ocean Earthquake. ” Geotechnical Journal,
JGS (in Japanese, in printing)

August 2012 Steel Construction Today & Tomorrow 14

The 2011 Great East Japan Earthquake

Treatment of Debris and Tsunami
Deposits, and Their Effective Utilization
for Restoration and Reconstruction
by Takeshi Katsumi, Professor, Kyoto University Graduate School of Global Environmental Studies
The Great East Japan Earthquake of March2011 produced tsunamis that generated a greatamount of debris and deposits, the appropriate
treatment of which has become a major task in
the reconstruction and restoration of thedisaster-stricken areas. In the three stricken
prefectures of Iwate, Miyagi and Fukushima,these materials exceed 22 million tons. In
Iwate Prefecture, for example, it is said thatthe waste generated by the earthquake in asingle moment is equivalent to 11 years ofnormal accumulation. Photos 1~3 show
tsunami deposits piled in a rice field, a temporary storage site mainly for tsunami deposits,
and a site for mixed waste, respectively.
Guidelines for the Treatment andRecycling of Debris and Tsunami Deposits

It is necessary to examine the treatment ofdebris and tsunami deposits from two perspectives: the treatment processing capacity of the

Clay layer
Sand layer
Original groundPhoto 1 Tsunami deposits (courtesy: T. Yasutaka)disaster-stricken areas and the structuring of
the recycling-oriented society currently being
promoted in Japan. Accordingly, two majorlines of treatment are being followed: one is
the separation and related processing needed torecycle and effectively utilize as much debris
and disaster-related waste as possible, while
the other one is the appropriate treatment anddisposal of debris and tsunami deposits that,
unfortunately, cannot be recycled. These twopaths were articulated as national policy soonafter the earthquake occurred. The role of theconstruction and reconstruction-operation
sectors will be important in promoting theeffective utilization of debris and tsunami
deposits.
In this regard, two guidelines have been
worked out by the Ministry of Land, Infrastructure, Transport and Tourism, into which theauthor has participated—namely, “Technical
Guidelines Concerning Improvements to Parks
and Green Tracts Involved in Reconstruction
Related to the Great East Japan Earthquake,”and “Basic Concepts for the Use of Recycled
Materials in Banking for Building Lot Development: Materials Suitable to be Conducive toPrompt Reconstruction and Restoration(Guidelines for Recycled Materials Banking in
Building Lot Development)”. These two guidelines offer commonly accepted, basic concepts
for improving parks and raising submerged
ground by the optimum use of various materials recycled from disaster waste.

Photo 2 Temporary storage site mainly for tsunami deposits
15 Steel Construction Today & Tomorrow August 2012

Tsunami Deposits

Included among the many kinds of debris andwaste materials generated by the disaster are
great amounts of soils called tsunami deposits. Accordingly, when using these deposits asconstruction and reconstruction materials, it isnecessary to appropriately separate the soils
and similar deposits from other materials.
There are many sorts of tsunami deposits withcorrespondingly diverse physical properties.
For example, the grain distribution of thetsunami deposits piled in rice fields is high insilt content, placing the distribution level outside the appropriate grain range shown in thecommonly-applied Manual for Earthworks inRivers. But the grain distribution of the soils
contained in the tsunami deposits piled in
temporary storage sites are acceptable (Fig.
1)1), 2).
One concern in the practical application ofthese soils and tsunami deposits is salinity.
Fig. 2 shows the measured results for chloride
contained in tsunami deposits in the rice fields
of a local coastal community in Fukushima
Prefecture. The measurements were conducted by extracting 38 specimens from thoserice fields in December 2011. The chloride
content of two-thirds of the 38 specimens was
2 mg/g or lower, while the number of specimens containing a chloride content of 1 mg/g
or lower fell to one-third, or 13 specimens1).
Conventionally, the chloride content of earthwork materials has been restricted to 1 mg/g

Photo 3 Temporary storage site for mixed disaster wastes

Percentage finer

Percentage finerFig. 1 Tsunami Deposits Accumulated in Rice Field (left) and Tsunami Deposits and Soils Transported and Piled in Temporary
Storage Site (right)1) 2)

Grain diameter

Grain diameter(Dotted line: Appropriate range of grain size shown in Manual for Earthworks in Rivers)

or lower in order to prevent corrosion in steel
pipe piles and other steel
Tsunami deposit (clay)
products applied underTsunami deposit (sand)ground. The Guidelines
Original groundfor Recycled Material
Banking in Building Lot
Development ollows thisguidepost. However,when considering the useof these tsunami deposits
to raise subsided ground
6
8
10
12
14
along the coast, it is only
Salinity (mg/g)
rational to permit theapplication of soils containing more chloride
than the specified value because the salinity
in the area’s underground water is high tobegin with. The Guidelines implicitly suggest

Fig. 2 Salinity of Tsunami Deposits1)
30
25
Number

20
15
10
5
0

0

2

4

Fig. 3 Typical Treatment Flow for Disaster Wastes
Mixed waste

Tsunami deposit composed
mainly of soils

Tsunami deposit composed
mainly of concrete waste

such applications.
Debris and Waste

As shown in Fig. 3, the debris and waste aresubjected to a rough preliminary sorting,and then to a secondary treatment consistingof crushing, sifting, wet or dry separation,and manual sorting. Tests were conductedon soil specimens at several temporary andsecondary sorting sites. The test results
show that high compaction performance canbe obtained when the presence of woodchips and other impurities is reduced (Fig.
4)2). These results demand that the level oforganic substances must be verified to bewithin allowable limits, in view of thepotential for long-term subsidence causedby the decomposition of organic substances, and that secondary treatment
must also be properly conducted.
Because the application of advanced
treatments improves quality, it is reasonable to selectively apply treatment levels
that are appropriate to reach the required
quality according to the effective volume.
In this regard, we have proposed the strategic treatment approach shown in Fig. 53).

Rough preliminary sorting

Column member,squared timber

Combustible
mixed waste

Incombustible
mixed waste

Waste
concrete

Metal
scrap

Toxic chemicals,
tatami mat, etc.

Recovery and utilizationof usable materials

Secondary treatment(advanced separation, sorting treatment)

Column member,squared timber

Combustible
material

Incombustible
material

Soil component(used asreconstruction
material)

Metal
scrap

Used as reconstruction material
Product manufacture or disposal
according to necessity

August 2012 Steel Construction Today & Tomorrow 16

Effective Utilization of Disaster Wastes

Fig. 4 Compaction Characteristics of Separated Soils2)
2.0

Numerical value: Percentage content of
combustible material
A-1
A-2
A-3
B-1
B-2
C-1
D-1
Sr =100
Sr = 90

Dry density ρd (g/c㎥)

1.8

1.6

1.4

1.2

1.0

0.8

0

10

20

30

40

50

Water content w (%)

Fig. 5 Image of Strategic Treatment Approach Taking into Account the Quality
Required for Application Purpose and Effective Applicable Amount3)

Disasterwaste

Occurrence sideRoughsorting
Separatedsoil Type C
Advancedsorting
Product
manufacture

Application side
Banking for park,raising, etc.

Separatedsoil Type B

Banking for otherpurposes, etc.

Separatedsoil Type A

Building
lots, etc.

References

Required quality and effective
applicable amount in application purpose
to which separated soils are applied

Optimized selection and applicationof treatment method

Table 1 Example of Properties of Tsunami Deposits4)
Specimen Soil particle densityNo.
(Mg/㎥)

Ignition loss(%)

Fluorine leaching(mg/L)

Arsenic leaching(mg/L)

No. 1

2.595

12.39

0.5

0.016

No. 2

2.708

1.05

0.2

0.004

No. 3

2.541

14.97

0.5

0.002

No. 4

2.743

3.62

0.2

0.002

No. 5

2.629

10.43

1.3

0.019

No. 6

2.781

2.52

0.2

N.D.

No. 7

2.838

4.95

0.5

0.004

No. 8

2.791

1.32

N.D.

N.D.

No. 9

2.801

9.65

0.4

N.D.

17 Steel Construction Today & Tomorrow August 2012

In the Tohoku area, where the current earthquake occurred, the existence of natural heavy
metals has been discussed. In the survey madeby us, tsunami deposits were found to dissolveout arsenic and fluorine at rates surpassing theenvironmental standards (Table 1)4). In light of
the fact that these deposits consist of soils
peculiar to the local area, appropriate measures based on suitable risk assessments will
be required in the use of these tsunami deposits. Another task is to respond appropriately toasbestos and other harmful substances contained in demolished structures and to radioactive substances as well.
Meanwhile, tracing technology, employing
an electronic toll collection system (ETC) andcell phone information terminals, is being
applied in the management of waste. In order
to effectively utilize disaster waste, it will benecessary to promote its application in publicsites while at the same time discussing its
treatment and effective utilization based on
careful risk assessment in line with social consensus. Expectations are high that “scienceand technology” can be used in an optimal
manner to pay close attention to local climaticconditions and will make effective and wiseuse of limited resources.
1) A. Takai, K. Endo, T. Yasutaka, T. Katsumi (2012): JGS Geo—Environmental
Research Committee for Great East Japan
Earthquake Disaster: Characterization ofDistribution Characteristics for Tsunami
Deposits in Coastal Area of Fukushima
Pref., Proceedings of the 47th Japan
National Conference on GeotechnicalEngineering (under contribution)2) K. Morita, T. Katsumi, A. Takai and T. Inui(2012): Compaction Characteristics ofWaste-mixed Soils Generated in Earthquake
and Accompanying Tsunami, Proceedings ofthe 47th Japan National Conference on Geotechnical Engineering (under contribution)3) T. Katsumi (2012): Waste GeotechnicsManagement and Reuse of Waste Materials, Proceedings of the 25th National
Congress for Environmental Studies, Science Council of Japan, pp. 99~104
4) T. Katsumi, A. Takai, K. Oomine, M.
Kazama and T. Inui (2011): Physical andChemical Characteristics of Tsunami
Deposits in Coastal Area of Miyagi Pref.,Transactions of 2011 Symposium on
Groundwater Ground Environment—
Water Environment Preservation andWater RaisingSteel Application Technology

Basic Details about Corrosion
and Corrosion Protection
by Hidenori Hamada, Professor, Dept. of Civil and
Structural Engineering, Kyushu University

Corrosion

The corrosion of metallic materials is a phenomenon in which metallic
materials, subjected to environmental actions during their use, undergo
surface changes due to chemical or electrochemical reactions.
Corrosion is classified into two types: dry corrosion and wet corrosion. Dry corrosion occurs when a metallic material is exposed to hightemperatures under moisture-less conditions and develops due mainly
to interaction with one or more gases. Wet corrosion results from theionization of metals under conditions in which moisture is present. In
addition to corrosion caused by natural ionization, wet corrosion also
includes corrosion induced by stray electrical currents.
Further, corrosion is also classified as general corrosion or local
corrosion. General corrosion denotes that a metallic material isuniformly corroded, and it occurs in cases when the environmental conditions are nearly identical over the entire surface of the metal. On theother hand, local corrosion denotes that the corrosive state is not
uniform, that there is partial deep pitting corrosion or grooved corrosion,and that the cause of the corrosion is the uneven distribution of environmental factors, non-uniform material quality, or galvanic action (contact
with a different metal).
Photo 1 shows local corrosion that occurred in steel sheet pileand steel pipe pile used for port structures. The structure in which local
corrosion occurred is in a very dangerous condition.

Mechanism of Corrosion

The micro-observation of steel product surfaces shows that there are
non-uniformities in the quality of steel products themselves, such as nonuniformity of mill scale and surface ruggedness. Further, the electric
potential on the surface of a steel product may not be uniform due touneven environmental conditions, such as differences in the moisture conditions (drying and wetting) on the product’s surface. As a result, anodic
and cathodic areas are formed on the product surface (Fig. 1). The chemical formula of the steel corrosion reaction is expressed as follows:• Anodic reaction(1)
Fe → Fe2++2eFe2++2(OH)- → Fe(OH)2(2)
4Fe(OH)2+O2+2H2O → 4Fe(OH)3(3)• Cathodic reaction
2H++2e- → 2H → H2 (in acid solution)(4)
2H++1/2O2 → H2O (in solution including oxygen) (5)
1/2O2+H2O+2e- → 2OH- (in neutral solution)(6)

Under conditions in which water and oxygen coexist, iron ions (Fe++)dissolve out due to anodic reaction (Formulae 1), while hydroxide ions (OH−)
are generated due to cathodic reaction (Formula 4~6). This is the first stageof corrosion cell formation. Next, Fe++ and OH− bond together (Formulae 2)
to form Fe(OH)2, which is then oxidized by dissolved oxygen to produce rust(corrosion) (Formulae 3).
To demonstrate this, steel test pieces (A1, B1, A2, B2 and C) were placedin two different environments: clay and sand (see Fig. 2). When test pieces
A1 and B1 were buried as shown in the figure, invisible minute anodic andcathodic areas occurred on their surfaces to form micro corrosion cells. In
this instance, the minute anodic and cathodic areas that form micro corrosion
cells were constantly changing their position along with the progress of thecorrosion reaction, thereby resulting in general corrosion of the steel products. On the other hand, when a single test piece is buried so that it simultaneously extends into two environments (sand and clay) with different conditions, such as piece C, or when two pieces in different environments areelectrically connected (test pieces A2 and B2 in the figure), macro corrosion
cells are formed. In the formation of corrosion cells in different environments,
an environment with a relatively high concentration of dissolved oxygen, i.e.
sand environment (pieces B1 and C), is likely to become a cathodic site,while an environment with a low concentration of dissolved oxygen, i.e. aclay environment (A2 and C), is likely to become an anodic site.
Corrosion not only in steel but also in other metallic materials is a statechange that occurs spontaneously in the natural environment. Controlling, orchecking, the rate of this state change is the goal of corrosion protection. The
study attitude differs greatly depending on how the corrosion is studied,whether in a macro prospective or micro perspective. From a micro perspective, the formation of anodic and cathodic areas is discussed by means ofelectrochemical theory, and the corrosion rate is examined using corrosion
current. Conversely, from a macro perspective, structures and structuralmembers are the topic of study and their corrosion rate is examined employing corrosion loss or corrosion area. In either case, the most important task incivil engineering is to accurately assess the level of structural soundness or,conversely speaking, the level of structural degradation.
Reference

Research Group on Corrosion Prevention of Steel Pipe Piles: Corrosion
Prevention Technology of Marine Steel Structures, Gihodo, March 2010
Fig. 1 Structure of Corrosion Cell
Electrolyte(seawater)

Fe++

Corrosion current

H+

H+

Cathodic area

Anodic area

Cathodic area

Fe(OH)2

Metal (Fe)

Fe(OH)3

Fig. 2 Model Test for Corrosion
Cell Formation

Clay
Sand

Photo 1 Local corrosion that occurred in port structures: steel sheet pile (left) and steel pipe pile (right)

A1, A2, B1, B2, C: Steel test pieces
August 2012 Steel Construction Today & Tomorrow 18

JISF Symposium

Symposium on Research into
Civil Engineering Steel Structures
The Japan Iron and Steel Federation (JISF) held its annual Symposium on Research into Civil Engineering Steel Structures on
March 13, 2012 in Tokyo. The symposium was held with morethan 300 people from a wide range of fields, such as government agencies, universities, highway and railway companies,
general contractors, and consulting offices, thereby producing
successful results.
The symposium has been held every year since 2005 withthe aim of publicly disseminating research results produced by
the “Steel-structure Research/Education Subsidy Program” promoted by JISF. The current 16th symposium focused especiallyon “Damage Resulting from the Great East Japan Earthquake
and Subsequent Restoration and Reconstruction Efforts,” featured lectures by prominent individuals in civil engineering inJapan, and was chaired by Prof. Yozo Fujino of the Graduate
School of the University of Tokyo.
The lecture programs offered reports on diverse civil engineering fields in which damage and restoration/reconstruction
measures were reported: port structures, railway structures,river levees, highway structures, tsunami deposits and debris,and ground liquefaction. (For details, see the lecture programs
below. Certain presentations adapt partially to the articles
used in the current issue.)Emeritus Prof. Nobuo Shuto of Tohoku University, the foremost researcher on tsunamis in Japan, delivered thesymposium’s annual special lecture entitled: “Together with
Tsunamis for 50 years.” His coverage of specific themes demonstrated valuable knowledge acquired through 50 years of
research on tsunamis, and touched on the types of damage
caused by tsunamis, the importance of tsunami-prevention
facilities, and the preparations for natural disasters including
the usefulness of software countermeasures.

• Damage to Highway Structures and Subsequent Restoration
and Reconstruction Efforts
Takashi Tamakoshi, National Institute for Land and Infrastructure Management, Ministry of Land, Infrastructure,
Transport and Tourism• Treatment of Debris and Tsunami Deposits, and Their Effective Utilization for Restoration and Reconstruction
Takeshi Katsumi, Professor, Kyoto University• Liquefaction-induced Damage to Houses and Buried Lifelines
Susumu Yasuda, Professor, Denki University• Special Lecture: Together with Tsunamis for 50 years
Nobuo Shuto, Emeritus Professor, Tohoku University• Address by Vice Chairman
Shigeo Takahashi, Port and Airport Research InstituteProf. Y. Fujino delivers chairman address

Lecture Programs• Address by Chairman
Prof. Yozo Fujino, Graduate School of the University of Tokyo• Damage to Port Structures and Subsequent Restoration andReconstruction Efforts
Takahiro Sugano, Port and Airport Research Institute• Damage to Railway Structures and Subsequent Restoration
and Reconstruction Efforts
Shinichiro Nozawa, East Japan Railway Company• Damage to River Levees and Measures for Restoration andReconstruction
Ikuo Towhata, Professor, The University of TokyoSTEEL CONSTRUCTION TODAY & TOMORROW
Published jointly by

The Japan Iron and Steel Federation
3-2-10, Nihonbashi Kayabacho, Chuo-ku, Tokyo 103-0025, Japan
Phone: 81-3-3669-4815 Fax: 81-3-3667-0245
URL http://www.jisf.or.jp/en/index.html
Japanese Society of Steel Construction
Yotsuya Mitsubishi Bldg. 9th Fl., 3-2-1 Yotsuya, Shinjuku-ku, Tokyo 160-0004, Japan
Phone: 81-3-5919-1535 Fax: 81-3-5919-1536
URL http://www.jssc.or.jp/english/index.html

Symposium scene

Edited byCommittee on Overseas Market Promotion The Japan Iron and Steel Federation
Chairman (Editor): Takeshi Oki
P u b l i s h e d t h r e e t i m e s p e r y e a r, S T E E L C O N S T R U C T I O N TO D AY &TOMORROW is circulated to interested persons, companies and publicorganizations to promote a better understanding of steel products and theirapplication in the construction industry. Any part of this publication may be
reproduced with our permission. To download content (PDF format), please go
our website at: http://www.jisf.or.jp/en/activitity/sctt/index.html. We welcome yourcomments about the publication and ask that you contact us at: sunpou@jisf.or.jp.