Joint Student Seminaron Civil Infrastructures
3-4 July 2008
Bangkok, Thailand
Co-Organized by
School of Engineering and Technology,
Asian Institute of Technology (AIT), Thailand
International Center for Urban Safety Engineering (ICUS)
Institute of Industrial Science
The University of Tokyo, Japan
BK-21 Global Leaders in Construction Engineering,
Korea University, Korea
Research Team for Maintenance Technology of Infrastructure,
Konkuk University, Korea
andKing Monkut’s Universityof Technology North Bangkok, Thailand

Edited by
Dr. Kyung-Ho Park, Dr. Shinji Tanaka and Dr. Seok-Won Lee

Organization Teams
Dr. Kyung-Ho Park (AIT, Thailand)
Dr. Pison Udomworrat (KMUT-NB, Thailand)
Dr. Shinji Tanaka (UT, Japan)
Dr. Wataru Takeuchi (UT, Japan)
Dr. Kawin Worakanchana (UT, Japan)
Dr. Shinya Hanaoka (TIT, Japan)
Dr. Jung-Sik Kong (KU, Korea)
Dr. Seok-Won Lee (KKU, Korea)
Dr. Young-Uk Kim (MU, Korea)

JOINT STUDENT SEMINARON CIVIL INFRASTRUCTURES
ICUS Report No. 30, July 2008

PREFACEAs our activities expand beyond the border, international collaboration
becomes more and more important. And, to build up a good relationshipwith other communities during young school days will be of advantage inthe future. Considering this background, we planned and organized “thejoint student seminar on civil infrastructure”, so as to foster international
friendship and communication among universities from 3 countries;
Thailand, Japan and Korea.
The objectives of this seminar are,1) to experience the organization of international seminar,
2) to improve the presentation skill,3) to share the research information and friendships.
The number of participants was 55, consist of 8 faculties and 47
students from Konkuk University, Myongji University, Korea Advance
Institute of Science and Technology, KMUT-NB, The University of Tokyo
and Asian Institute of Technology universities. On the first day, we had apresentation session, having 5 faculties’ lectures and 17 students’presentations. The topics were varied from all areas of civil engineering andevery student did their best in his/her presentation as well as in thediscussion. On the second day, we had a field visit to the Suvarnabhumi
airport rail link and city air terminal project. Looking at a huge scale project,
the students could learn technologies, project management, culturaldifferences, and so on.
Although it was a first trial of this kind of joint seminar, it was really
successful and fruitful judging from the students’ response. We believe thisseminar gave not only knowledge and information but also a lot of otherstimuli to the students. And we hope to continue to hold this kind ofinterchange activities in the future, too.
Finally, we would like to express our sincere gratitude for those who
kindly supported and contributed to the success of this seminar.

KYUNG-HO PARK, SHINJI TANAKA, SEOK-WON LEE

ICUS Report 30

Table of Contents
Page
Opening Session
SECTION 1
Invited Lectures

SECTION 2

Seismic evaluation of existing reinforced concrete buildings
Pennung Warnitchai

1

Early earthquake warning system in Japan
Kimiro Meguro

27

Geophysical characterization of geo-materials
Gye-Chun Cho

45

Trend of traffic accidents and its characteristics in Japan
Shinji Tanaka

71

Bond strength of concrete interface by using fracture mechanics approach
Pison Udomworarat

81

Student Presentations
Intermodal model choice between Japan and Russia
Tomoya Kawasaki

93

Non-linear behavior of new type girder filled by high-strength concrete
Sung-Woo Choi

103

Elastodynamic analysis by BEM using DDM and particular integrals
Adisorn Owatsiriwong

109

Evaluation of wildfire duration time over Asia using MTSAT and MODIS
Yusuke Matsumura

119

Shear behavior of particles with respect to bonding state by using PFC2D
Seon-Ah Jo

127

Behavior of soft ground installed with expanding vertical drain
Phuong Tung Hoang

141

Utilizing heterogeneous engineering in concrete material innovations forsustainable development
Michael Henry149

A simplified 3D numerical simulation for Bangkok MRT subway tunnel
Tran Viet Dung

155

Seismic behavior of precast hybrid moment resisting frames
Ekkachai Yooprasertchai

165

Laboratory stiffness measurements on Toyoura sandHiroaki Ebizuka

175

Joint Student Seminar on Civil Infrastructures

July 2008, Thailand

SECTION 3

Weakly-singular integral equations for cracks in 3D linear piezoelectric finite
media
Weeraporn Phongtinnaboot183

Undrained shear strength estimation of marine clay using shear wave velocity
Tae-Min Oh

191

Seismic retrofitting promotion model for masonry houses using PP-band
method and micro-earthquake insurance
Naoki Sorimachi

201

Stiffness characteristics of vanishing mixtures
Yong-Hun Eom209

OD variation analysis on the Tokyo Metropolitan Expressway using ETC-OD
Data
Hiroaki Nishiuchi

219

Study of properties of para-rubber plates for using as the capping on concrete
specimens for compression test instead of molten sulphur
Kittipong Suweero

229

Particle associated discharge of pathogen indicator organisms from diffuse
sources in agricultural-forestry watersheds
Kyung-Min Han

237

Physical properties of grout for close-loop vertical ground heat exchanger
Chul-Ho Lee

247

Estimation of ultrasonic cavitation energy in a large-scale sonoreactor
Young-Gyu Son

259

Use of superfine crumb rubber to improve thermal & sound properties ofconcrete
Piti Sukontasukul

265

Student Report
Report from Student Participants on The Joint Student Seminar on Civil
Infrastructures
Naoki Sorimachi, Tomoya Kawasaki, Hiroaki Ebizuka, Michael Henry, Hiroaki
Nishiuchi, Yusuke Matsumura, Sung-Woo Choi, Adisorn Owatsiriwong, Tran Viet
Dung, Ekkachai Yooprasertchai and Kittipong Suweero

279

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Welcome board

Registration

Booth at seminar

Opening ceremony (Dr. Park)

Dr. Pennung WarnitchaiProf. Kimiro Meguro

Dr. Gye-Chun Cho

Dr. Shinji Tanaka

Joint Student Seminar on Civil InfrastructuresiJuly 2008, Thailand

ii

Dr. Pison Udomworarat

Mr. Tomoya Kawasak

Mr. Sung-Woo Choi

Mr. Adisorn Owatsiriwong

Mr. Yusuke Matsumura

Ms. Seon-Ah Jo

Mr. Phuong Tung Hoang

Mr. Michael Henry

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Mr. Tran Viet Dung

Mr. Ekkachai YooprasertchaiMr. Hiroaki Ebizuka

Mr. Weeraporn Phongtinnaboot

Mr. Tae-Min Oh

Mr. Yong-Hun Eom

Mr. Hiroaki Nishiuchi

Mr. Naoki Sorimachi

Joint Student Seminar on Civil Infrastructuresiii

July 2008, Thailand

Mr. Kittipong Suweero

Presentation Airport Rail Link

Field Trip: Airport Rail Link and City Air Terminal

Group Photoiv

Joint Student Seminar on Civil Infrastructures

Invited Lectures

SEISMIC EVALUATION OF EXISTING
REINFORCED CONCRETE BUILDINGSPENNUNG WARNITCHAI and MATRIN SUTHASIT
School of Engineering and Technology
Asian Institute of Technology, Thailand
pennung@ait.ac.th

Seismic Performance Evaluation of Existing
Reinforced Concrete Buildings

Sichuan Earthquake
Magnitude = 7.9

Pennung Warnitchai and Matrin Suthasit
School of Engineering and Technology
Asian Institute of Technology

Kashmir Earthquake (Oct 8, 2005)
Magnitude = 7.7

1

July 2008, Thailand

Balakot, Kashmir Earthquake (2005)
Magnitude = 7.7

BPKP Building (Sewon, Yogyakarta, 2006)

Yogyakarta Earthquake (2006)
Magnitude = 6.2

2

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

ISI Building (Sewon)

Yogyakarta Earthquake (2006)
Magnitude = 6.2

Brittle Failure in Column

Seismic Evaluation of Existing Reinforced Concrete Buildings

3

July 2008, Thailand

Nonductile Reinforcement Details
Low Transverse Reinforcement

High Longitudinal Reinforcement

Lap-Splice in Potential Plastic Hinge Region
Construction Joints

Non-Uniform Flexural Capacity
Non-Uniform Shear Capacity

No Joint Reinforcement
Discontinuous Positive Beam Reinforcements
Short Embedment Length into Columns

Reversed Cyclic Loading Test of
RC Columns with Short Lap Splices

4

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

SHEAR
FAILURE

Changing of Design
Parameters

LAP-SPLICEFAILURE

Force Deformation Relation
Load (kN)

Story Drift (%)

Seismic Evaluation of Existing Reinforced Concrete Buildings

5

July 2008, Thailand

Modeling of RC Columns
Material Properties
Stressnonlinear shear spring

Strainfiber-section element
linear-elastic frame element(shear deformation excluded)

Member Geometry +Reinforcement Detailnonlinear shear spring

Lateral Load (kN)

Experiment
Mode of Failure:
Lap-Splice Failure

Analysis150

Story Drift (mm)1000Mode of Failure:
Lap-Splice Failure-50

Lateral Load (kN)

+95 kN50-81 kN-100

Story Drift (mm)
-150
-80

6

-40

0

40

80

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Lateral Load (kN)

Experiment
Mode of Failure:
Lap-Splice Failure

Analysis

400
300
200
100

+174 kN

0

Mode of Failure:
Lap-Splice Failure

Lateral Load (kN)

Story Drift (%)-100-185 kN-200-300

Story Drift (mm)
-400
-12

-8

-4

0

4

8

12

Lateral Load (kN)

Experiment
Mode of Failure:
Shear Failure

Story Drift (mm)Mode of Failure:
Shear Failure

Lateral Load (kN)

Analysis

Story Drift (mm)Seismic Evaluation of Existing Reinforced Concrete Buildings

7

July 2008, Thailand

Lateral Load (kN)

Experiment
Mode of Failure:
Shear Failure

Analysis80
66.83 kips
60

Lateral Load (kN)

Story Drift (mm)

40
20
0

Mode of Failure:
Concrete Crushing

-20
-40
-60

-71.54 kips

Story Drift (mm)

-80
-3

-2

-1

0

1

2

3

Beam-Column Joint Failure

8

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Beam-Column Joint Failure

Balakot, Kashmir Earthquake (2005)

Cyclic Loading Test of a Beam-Column Sub-assemblage

Hydraulic Actuator

Seismic Evaluation of Existing Reinforced Concrete Buildings

9

July 2008, Thailand

Failure Mechanism
0.5% Drift

2.5% Drift

3% Drift

6% Drift

19

BC-Joint Model
Reinforcement
Anchorage

Joint Shear
Mechanism

10

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Modeling of Beam-Column Joint
Fbr

Fbl
bond-slip springVcu
nonlinear rotational
spring
Mc

F’cu

Fcu

bl

Mcbr

Vcl
F’br
F’bl

Mccu

steel spring

nonlinear axial spring

Mccl
Vbr

Vbl
Fcl

F’cl

Lateral Load (kN)

Experiment
Mode of Failure:
Joint Shear Failure

Analysis

Mode of Failure:
Joint Shear Failure

Lateral Load (kN)

Story Drift (%)

Story Drift (%)

Seismic Evaluation of Existing Reinforced Concrete Buildings

11

July 2008, Thailand

Flexural
Failure in
Beams
Changing in Design Parameters results in Different Mode of Failure

Joint-Shear
FailureLateral Load (kN)

Experiment
Mode of Failure:
Beam Reinforcement
Yielding

Analysis

Mode of Failure:
Beam Reinforcement
Yielding

Lateral Load (kN)

Story Drift (%)

Story Drift (%)

12

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Masonry Infill Wall Failure

Quasi-Static Experiment of GLD RC framewith infill wall conducted by Mehrabi et al.
(1994) at University of Colorado, Boulder

Seismic Evaluation of Existing Reinforced Concrete Buildings

13

July 2008, Thailand

3-Strut Model for Infill Wall Panel

Comparison—RC Frame with Masonry Infill Wall
Lateral Load (kN)

Experiment

Mode of Failure: Infill Wall Failure
Story Drift (%)
120

Analysis

Lateral Load (kN)
90
60
30
0

Mode of Failure: Infill Wall Failure

-1.6

-1.2

-0.8

-0.4

0
-30

0.4

0.8

1.2

1.6

Story Drift (%)

-60
-90
-120

14

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Typical Reinforced Concrete Commercial Buildings

VULNERABILITY FACTORS Non-seismic Detailing Strong Beam–Weak Column
 Soft/Weak First Story
 Torsional Irregularity
 Frame-Infill Interaction

3D-view generated by SAP2000 v10

Seismic Evaluation of Existing Reinforced Concrete Buildings

15

July 2008, Thailand

Framing Systems

A

B

1

A

2

B

3

C

C

1

2

3

Typical Floor Plan

Pushover Analysis
Earthquake Induced
Lateral ForceRoof Drift(Δr)

1st – Mode
Deformation ShapeBase Shear
(Vb)

16

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Pushover Curve - Bare Frame
Base Shear
Coefficient
Vb/W
0.15

0.1

splice failure

0.05

P-Δ
Instability

concrete crushingsteel yielding

Normalized Roof Drift (%)

00Base Shear
Coefficient
0.35

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Effects of Masonry
Infill Walls

increasedlateral strength0.30

abrupt and severe
strength degradation
0.25

higher fundamental
period attracts
more seismic
demand

0.20

0.15

0.10

0.05

Normalized Roof Drift (%)

0.00
0

0.5

Seismic Evaluation of Existing Reinforced Concrete Buildings

1

1.5

17

July 2008, Thailand

Failure Mechanism

splice failure
concrete crushingsteel yielding

3D Nonlinear Dynamic Analysis

3D nonlinear
response

Bi-axial
Dynamic Ground
Excitation

18

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Elastic Dynamic Response (Modal Analysis)

Lateral-Torsional Movement (period = 0.50 sec)

Soft-story Collapse of RC Buildings in the 1999 Chi-Chi Earthquake(Taiwan)

38

Seismic Evaluation of Existing Reinforced Concrete Buildings

19

July 2008, Thailand

Applied Earthquake Ground Motions
Strong Motion Recorded
during Loma Prieta EQ

acceleration (g)
+0.30

X
Y

+0.20

time (sec)

-0.00
0

10

20

30

-0.20
-0.30

X

PGA = 0.30g

Y(Alluvium Sites)

Building Response in X-direction
Y
1st Story
Drift (%)

X

3.00
2.00
1.00
0.00
0.00
-1.00

Time
(sec)
0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

-2.00
-3.00
-4.00

20

Frame-1
Frame-3

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Building Response in X-direction
Y
1st Story
Drift (%)

X

3.00
2.00
1.00
0.00
0.00
-1.00

Time
(sec)
0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

-2.00
-3.00

Frame-1
Frame-3-4.00

Building Response in X-direction
Y
1st Story
Drift (%)

X

3.00
2.00
1.00
0.00
0.00
-1.00

Time
(sec)
0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

-2.00
-3.00
-4.00

Seismic Evaluation of Existing Reinforced Concrete Buildings

Frame-1
Frame-321

July 2008, Thailand

Building Response in X-direction
Y
1st Story
Drift (%)

X

3.00
2.00
1.00
0.00
0.00
-1.00

Time
(sec)
0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

-2.00
-3.00

Frame-1
Frame-3-4.00

Building Response in X-direction
Y
1st Story
Drift (%)

X

3.00
2.00
1.00
0.00
0.00
-1.00

Time
(sec)
0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

-2.00
-3.00
-4.00

22

Frame-1
Frame-3

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Building Response in X-direction
Y
1st Story
Drift (%)

X

3.00
2.00
1.00
0.00
0.00
-1.00

Time
(sec)
0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

-2.00
-3.00

Frame-1
Frame-3-4.00

Building Response in X-direction
Y
1st Story
Drift (%)

X

3.00
2.00
1.00
0.00
0.00
-1.00

Time
(sec)
0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

-2.00
-3.00
-4.00

Seismic Evaluation of Existing Reinforced Concrete Buildings

Frame-1
Frame-323

July 2008, Thailand

Building Response in X-direction
Y
1st Story
Drift (%)

X

3.00
2.00
1.00
0.00
0.00
-1.00

Time
(sec)
0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

-2.00
-3.00

Frame-1
Frame-3-4.00

Building Response in X-direction
Y
1st Story
Drift (%)

X

3.00
2.00
1.00
0.00
0.00
-1.00

Time
(sec)
0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

-2.00
-3.00
-4.00

24

Frame-1
Frame-3

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Building Response in X-direction
Y
1st Story
Drift (%)

X

3.00
2.00
1.00
0.00
0.00
-1.00

Time
(sec)
0.50

1.00

1.50

2.00

2.50

3.00

3.50

-2.00
-3.00

O

-4.00

4.00

o
ge
r
e
nV

4.50

ps
lla
o
fC

e

Frame-1
Frame-3

Incremental Dynamic Analysis
Max Story
Drift (%)
Collapse Limit State
This Point is Obtained
from Previous Analysisner Zo ge)
a
e
n
i
a
L
r d amonim(Seismic Evaluation of Existing Reinforced Concrete Buildings

e
on e)
Z
g
r
ea amanidnl
No gheri(h

PGA (g)25

July 2008, Thailand

Seismic Retrofitting of Torsional irregularity

26

Solid walls should
be of nonstructural
cladding

Shear walls areadded at or near the
open faceStrength and stiff
moment-resistingor braced frame isdesigned for soft
front wall

Torsion is accepted,
and building isdesigned to resist theforces and minimize
the distortion theycause

Joint Student Seminar on Civil Infrastructures

EARLY EARTHQUAKE WARNINGSYSTEM IN JAPANKIMIRO MEGURO
International Center for Urban Safety Engineering
Institute of Industrial Science, The University of Tokyo, Japan
Department of Civil Engineering, The University of Tokyo, Japanmeguro@iis.u-tokyo.ac.jp

Early Earthquake
Warning System
in Japan
Kimiro MEGURO
Director and Professor
International Center for Urban Safety Engineering
Institute of Industrial Science
The University of Tokyo

Disaster Management System
for Disaster Reduction
Risk Management
Preparedness
Mitigation

Prediction and
Early Warning
DisasterReconstruction
Recovery

Damage/Impact
Assessment
Disaster Response

Crisis Management

27

July 2008, Thailand

Early earthquake warning system(Processes and tasks)
Cars / Highways / Tunnels
Bullet train

Power stations

Seismometer
Information
providers

Data analysis
P-waveJMA

Houses

S-waveFactories

Data acquisition

High-rise buildings

Users
Data transmission

OfficeHospitalTV

P-wave S-wave
Underground seismometer
P-wave and S-wave
wave fronts
Hypocenter(rupture
starting point)
Fault rupture

SYS

Accuracy of Current Early Earthquake Warning System
Difference on calculated seismic intensity and really observed one(seismic intensity: 4 or more, 350 events)
calculated seismic intensity

reallyobserved
seismic
intensity
JMA has started operation ofearly earthquake warning
system since October 1st 2007.

28

Agree:
21 %Within +/- 1 : 75 %Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Accuracy of Current Early Earthquake Warning System
Difference on arrival time (seismic intensity: 4 or more, 350 events)(calculated arrival time - really observed one)
Numberof events

Time Difference (sec)(calculated arrival time - really observed one)

取り上げた３つのシナリオ地震
Three scenario earthquakes①想定東海地震：expected Tokai Eq.
分野別被害予測がなされている地域の想定地震②想定宮城県沖地震：expected Miyagi-ken-Oki Eq.
近々に大きな地震が発生すると認識され、緊急地震速報がその効果を発揮すると考えられる猶予時間が大きな海洋性地震③１９９５年兵庫県南部地震：1995 Kobe Eq.
震源が内陸に近く猶予時間が少ないため、緊急地震
速報の効果があまり望めない地震

Early Earthquake Warning System in Japan

29

July 2008, Thailand

猶予時間別被害軽減率の仮定
Assumption for discussion on effects of EEW system

人的被害
Human
Casualty

Based on pastexperimental results
during day time
今回の例では、小学校や工場などでの実証実験の結果に基づいていることから、発災時間としては「日中、活動中」を想定している。

軽減前被害WO info.
軽減後被害
死傷
重傷
中等傷
地
死傷 Dead75
状
重傷 Heavily Inj. 15
75
2秒
中等傷Moderately 5
1575 移
無傷 No damage
5
10
25
学
死傷 Dead20
徒重傷 Heavily Inj. 60
20
5秒
中等傷 Moderately 10
50
20 な
無傷 No damage 103080
死傷 Dead10
重傷 Heavily Inj. 30
1010 秒
中等傷 Moderately 50
30
10
無傷 No damage 1060
90
死傷 Dead5
重傷 Heavily Inj. 15
520 秒
中等傷 Moderately 30
15
5
無傷 No damage
50
80
95（数字は被害移行率： ％）L Time (s) Reduce ratio
猶予時間

想定東海地震による静岡県の主な都市と猶予時間
Leading time at major cities in Shizuoka Pref.
In Case of the Expected Tokai Eq.
LocationCity
Area

L.Time (s)Time (s)

猶予
地域
主な都市
緯度
経度
時間（秒）
伊豆
下田市
34 .67 6 13 8.948
16.6
熱海
伊東市
34 .96 2 13 9.105
23.8
東部
沼津市
35 .09 2 13 8.867
22.4
富士
富士市
35 .15 8 13 8.679
21.3
中部
静岡市
34 .97 2 13 8.386
13.7
志太・ 棒原 藤枝市
34 .86 4 13 8.261
9.8
中遠
磐田市
34 .71 4 13 7.854
4.6
北遠
天竜市
34 .86 9 13 7.819
8.8
西部
浜松市
34 .70 8 13 7.730
5.0
震源情報： N3 4.203, E1 37 .93 9, D30, M8.0
地震発生から震源決定まで12 秒であると仮定

分類（秒）
10
20
20
20
10
5
2
5
5

Assuming that it takes 12 seconds to identify the location andmagnitude of the event.

30

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

猶予時間別人的被害想定と推定被害軽減効果
Disaster reduction effects by EEW system（対象：東海地震(M8.0),昼12時,予知無）（in case of Tokai Eq. with M8.0,12:00,without Eq. prediction）
Heavily Inj. Moderately No damage
緊 急 地 震速 報 な し Without EEWS
猶予時間
死者数 Dead 重傷者数
中等傷者数 無傷
2秒
392
1 889
8 760
1 047
5 305
23 884
L. Time (s) 5 秒
10 秒
1 152
4 358
19 724
20 秒
1 094
5 027
22 196
total 合計
3 685
16 57974 564

With EEWS
緊 急 地 震速 報 あ り 合計
軽減率 (% ) Reduction Ratio

673
82

4 362
74

20 45573

69 338推定人的被害軽減量/Estimated No. of human casualty reduction
死者/Dead：約3000人(-82％）、重傷者/Heavily Inj.：
約12,000人(-74％）、中等傷者/Moderately：約54,000人(-73％）、無傷者/No damage：＋約69,000人

緊急地震速報を取り巻く基本的な理解(1)Basic understanding on early earthquake warning system (1)◆「緊急地震速報」は有効活用することで大幅な被害軽減が達成される可能性が高い
Early Earthquake Warning System is very useful for disaster
reduction when it is used properly.

・死者の軽減効果（理想的条件下）は想定東海地震（82％減）、Expected Tokai Eq.
宮城県沖地震（94％減）、Expected Miyagi-ken-Oki Eq.
1995年兵庫県南部地震（１％減）、1995 Kobe Eq.

・エレベータ閉じ込め事故の軽減効果は、
千葉県北西部地震（M.6.0, 2005/7/23,16:34）で97％減、宮城県沖地震（M7.2, 2005/8/16, 11:46）で100％減。

Early Earthquake Warning System in Japan

31

July 2008, Thailand

緊急地震速報を取り巻く基本的な理解(2)Basic understanding on early earthquake warning system (2)◆「緊急地震速報」を有効活用するための事前準備の重要性
・技術的課題と環境整備（制度を含む）にかかわる課題◆ Importance of preparation on both technology and social issues
before the event
・Without this, the system cannot be used for disaster mitigation.

◆「緊急地震速報」を有効に活用できないケースの存在
・「緊急地震情報」の適切な活用と、これに過度に期待しない仕組みとの両輪体制の整備
・インフラや建物の耐震補強への積極的に取り組み◆ Cases when the system is not effective
・Development of two systems: 1) a system that makes proper useof the ‘Early earthquake warning’; and 2) a system that does notdepend too much on the ‘Early earthquake warning’・Active promotion of infrastructure and house retrofitting

Basic Knowledge
for Effective Use of
Real-Time Earthquake Information,
Earthquake Early Warning System

32

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Basic terminologies
L: Focal distance, Ｌ＝Δｔ・Vp・Vs/（Vp-Vs）
震央距離
Epicentral
distance

Fault surface rupture(In case that there is one)

Observation
観測点
point

Epicenter
Surface wave
震央

Ground surface

Focal Depth

Body wave

ca
Fo

ce
an
t
is
ld

屈折
R
efraction
ve
wa
y
d
Bo

Hypocenter(Rupture origin)

Fault

Types and characteristics of seismic waves（In order of wave propagation velocity,
P-wave＞S-wave＞Surface-wave）
P-wave （Primary wave）
Body waves

Seismicwaves(Travel directlyfrom thehypocenter to theobservation point.)

Surface waves

Wave
direction
Propagation direction

S-wave （Secondary wave）(Shear, transverse wave. Its
component is perpendicular to the
propagation direction. Usually felt asside movement. Propagation velocity
is slower than that of P-waves.

L: Focal distance

Ｌ＝Δｔ・Vp・Vs/（Vp-Vs）

地表面
Ground surface
Body wave

Fault

Ｓ-waveWave
Propagation direction direction

Epicenter Surface wave
震央
Focal
Depth

（Travel to the surface
and then to theobservation point.
Propagation velocity isslower than that ofbody waves. Affects
large tanks and bridge,
and high rise buildings.
Two types: Rayleighand Love waves.)

Early Earthquake Warning System in Japan

Ｐ-wave(Longitudinal, compression wave. Its
component is along the propagation
direction. Usually felt as an up-down
movement. It has a high propagation
velocity)

Observation
観測点
point

Focal distance
Body wave
Hypocenter（Rupture origin）

33

July 2008, Thailand

Three important characteristics
of ground motion causing damage(1995 Kobe ground motion observed at Kobe Marine Meteorological Observatory)EW-Component

PGA = 619(Gal)

D: Duration

A: Amplitude
P-waveNS-Component

PGA = 820(Gal)S-waveUD-Component0

Q: Frequency

10

PGA = 333(Gal)30(sec)20

Issues for Effective Useof Early Earthquake Warning System-Issues in General-Issues for information providers
to provide quickly and correctly-Issues for information receivers
to respond quickly and correctly

34

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Earthquake early warning system(Processes and tasks)
Cars / Highways / Tonnels
Bullet train

Power stations

Seismometer
Information
releaseData analysis
P-waveS-waveMeteorological
AgencyHouses

Factories

Data acquisition

High-rise buildings

Data user
Data transmission

OfficeHospitalP-wave S-wave
Underground seismometer
P-wave and S-wave
wave fronts
Fault rupture Hypocenter (rupture starting point)

Outline of the tasks involvedin the earthquake early warning
1）The nearest seismometer detects P-waves.
２）This information is promptly sent to JMA.
３）JMA evaluates the event location, occurrencetime, magnitude, etc.
４）JMA sends these information to broadcastingand disaster related organizations.
５）These organizations send the information
accurately and promptly with due considerationof the users.
６）Users make the most of this information basedon their situation and the available time for action.

Early Earthquake Warning System in Japan35

July 2008, Thailand

Earthquake early warning system(Processes and tasks)
Cars / Highways / Tonnels
Bullet train

Power stations

Seismometer
Information
releaseData analysis
P-waveS-waveMeteorological
AgencyHouses

Factories

Data acquisition

High-rise buildings

Data user
Data transmission

OfficeHospitalP-wave S-wave
Underground seismometer
P-wave and S-wave
wave fronts
Fault rupture Hypocenter (rupture starting point)

How do ground motion characteristics
affect damage?
Source characteristics
Representative
parameters

Magnitude（M）(Source effect)
LargerSmaller

A: Maximum
amplitude

BecomeslargerBecomessmaller

D: Strong
motionduration

BecomeslongerBecomes
shorterQ:
Frequency
content

Low
frequency
component
increasesHighfrequency
component
increases

36

Propagation pathand distance
Focal distance(Between observation
point and fault)LongerShorter(Further)(Closer)
Becomessmaller(Attenuated)

Local site effectGround conditions
Topography
Hard
soil

Soft soil
Amplification

NochangeNochange(However, if soilliquefies, theshaking becomesless intense)NochangeNochangeBecomeslongerBecomes longer(However,amplitude becomes
smaller, thendamage decreases)

Low frequency
content
increases(Because highfrequency
component
attenuates faster)NochangeNochangeLow frequency
content
increases(Predominantperiod becomes
longer, lowfrequency waves
amplify)

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Relation between ground motion
parameters and earthquake early warning
Sourcecharacteristics

Relation
to earthquake
early
warning

Propagation
distanceand path

There is a trade off
The time between the
between accuracy andwarning and thetime. Earthquake is an
shaking is shorter if thespatial and temporal
focal distance is shorter.
event and its magnitude
The warning system is
becomes bigger as thenot so effective forfault plane area becomes locations close to thelarger. In case of a large epicenter of large
earthquake, it takes time earthquakes. Thisfor the rupture to takeareas are expected toplace. As a result, it takes have the largest
time to identify it anddamage. The system isissue the warning, leaving most effective forshorter time for action. If locations not so close to
the warning is issued
the epicenter of a large
sooner – with lessearthquake.
certainty – more time foraction is available but
also a larger chance of an
inaccurate evaluation.

Observation point
topography,
soil conditions, others
Even for the same magnitudeand focal distance, theshaking amplitude, frequency
content and duration can bevery different depending on
the observation location.
Even in the same building,the shake at the basement or
at higher up floors is very
different. In a car, on a
viaduct or a bridge, the shakeis affected by the dynamic
response of the viaduct/
bridge. At a building
construction site, theresponse changes with thechanging characteristics ofthe structure being built.

Lessons Learnt from Recent Disasters◆Importance of Structural Strength◆Lack of Imagination Capability◆Politicians, Governments,◆ Researchers, Scientists
and◆Mass Media, General Public

Early Earthquake Warning System in Japan37

July 2008, Thailand

年
５年
３年
２年
１年
６ヶ月
３ヶ月
２ヶ月
１ヶ月
２週間
１週間
３日
２日
１日
時間
６時間
３時間
２時間
１時間
分
分
５分
２分
１分
秒
秒
秒

What will happen around you when you
feel strong ground motion?
Earthquake
地震の発生 3 10 30

0： 00

a

b c d eA1 A1aA1

3： 00 sleeping
A2・・
commutingAn

10→ → → →→ → → → → → → → → →→ → → →→ → → → → → → → →Typical daily
life activity

12

10 30

f g

h i

j

k l

m n o

p

q r

s

t

u v w x y

z z’

A1
A1ｈ

Your typical daily life activity

6： 00 rising

9： 00
Business B1
In AM

12： 00 lunch

B2

15： 00 BusinessB3
in PM

・
・
18： 00commutingP1
・・
21： 00
・
Pn
24 00

B1
B1e

secondWeek/monthminute
B3
B3b

B3さ

hour
day

P1
P1e

year

P1
P1o

：

Important points
in Meguro Method
１．徹底した当事者意識
Fully understanding that earthquake is your own problem

２．健常者＝潜在的災害弱者の認識
Abled person = temporary undisabled person

３．個人としての多面性の認識
Understanding multiple tasks that individual person has

４．自分の死後の物語を考える
Consider the story after you died in disaster

38

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

What can you do
before the earthquake occurrence?
Earthquake
地震の発生 occurrence

秒sec
秒sec
秒sec
１分min
２分min
５分min
分
min
分
min
１時間
hour
２時hours
間
３時間
hours
６時hours
間時hours
間
１
１日day
２日
days
３日
days
１週week
間
２週
間
weeks
１ヶ
月
month
２monthsヶ月
３ヶ月
months６monthsヶ月
１１年year
２years
年
３years
年
５years
年
年
years
10 5

3 2

6 3 2 1 2

1

10

2

3

12 6 3 212
1 30
5 2 1 30
10 3
30 10
30 10
3
10

→→ → → →→ →→→ → → → → →→ → → →→→→ → → →→ → →あ い うえ お か き く けこ さ し す せ そ た ちつ て と な に ぬ ね の は ひ

1Earthquake
地震の発生 occurrence

秒sec
秒sec
秒sec
１分min
２分min
５分min
分min

分min
１時間
hour
２時hours
間
３時hours
間
６時間
hours
時hours間
１１日
day

10 5 2 1 30
10 3
30 10
3

30 10
30

→ → → → →→ → →→ → → →→ →
1日の
Daily
routine
生活パターンpattern

0：00

3：00

Sleeping
睡眠中

あ い う え お かき く けこ さ し す せ そA1 A1あ

A1く

曜Day
日／/ 季
節／天/ 候別SeasonWeather

業Activities
種別／会社
別／利用主
の活動
dependingon体business,company, subject

1212 6 3 2

A2・
6：00 Wake・
起床up
Commuting
通勤 An

9：00 Morning
午前中 B1

B1かActivitiesの勤務

12：00 Lunch
昼食

B2

Afternoon

午後 B3
15：00 Activitiesの勤務

・・
18：00Commuting
通勤 P1
・
・
21：00
・
Pn

B3い

B3さ

P1お

24：00

Integrated Disaster
Information Station
Damage estimation Kobe Eq. lessons
Dynamic behavior
of Interior facility

Exp1 Exp2

Ground motion..

Numerical

Data Archive

Vulnerability analysis

Universal Disaster
Environment Simulator
To Generate Disaster Information

Fire spreading.

New style disaster database

Structural Collapse

Human
Evacuation

WTC attack

Past Eq. Disaster
information

E-learning System
Nest generation disaster Meguro Method, Disastermanagement manual
imagination tool

Information Gateway

Information interface using touch panel
Evaluation of effects ofcountermeasures

Early Earthquake Warning System in Japan

Economical effects

Internet

39

July 2008, Thailand

Direct and Indirect Effectsof earthquake early warning

Effects of early earthquake warning（Direct effects are usually discussed. However, indirect
effects are also very important, often overlooked, andshould be discussed.）

Directeffect40

IndirecteffectPositive
impact

Early earthquake
warning canreduce damage

Opportunity topromote disastercountermeasures
before the event

Negative
impactImproper use of
the disclosed
information may
lead to moredamage.

-Unreal sense of safety
hampering disastercountermeasure
implementation-Influence on stock market,
etc.

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Levels of effectsof early earthquake warning
DirecteffectIndirecteffectPositive
impactNegative
impactIssues for efficient useof early earthquake warning◆ Discussion/consideration on how to use
this system under different conditions

Different uses, available time, occurrence time,←Discussion
information accuracy, user spatial/temporal location (Meguro◆ In case of a system problem(failure to disclose, unsent warning, etc)

method)Failed safe system，redundancy, back-check system◆ System/structure to avoid misusing
correct information
Education system set in advance

Reliablesystemmanagement

From your side,
what is the most important issue?

Early Earthquake Warning System in Japan

41

July 2008, Thailand

Key points for efficient use (1)From the warning issuing agency view point…
◆Improvement of disaster imagination capacity
・Information disclosure with its proper way of use(before and during the event)◆Multiple steps information disclosure
considering the capacity of the user
・From simple to advance use of the information◆Continuous efforts towards higher accuracy and reliability
・Methodology and system◆Education of users for better understandingof ‘Early earthquake warning’ including the situations
in which it cannot be effectively used for any reasons
・Development of two systems:
1) a system that makes proper use of the ‘Early earthquake warning’; and2) a system that does not depend too much on the ‘Early earthquake warning
・Active promotion of infrastructure and house retrofitting

Key points for efficient use (2)From the viewpoint of the users…

◆Improvement of disaster imagination capacity

・Personal base (company, commuting way, town, family, room, etc)

◆Improvement of the understanding on ….
・Meaning (Usefulness and limitation) and the use of‘Early earthquake warning’
・Importance of preparation and training before theevent
・Without this, the system cannot be used
for disaster mitigation.

・Cases when the system is not effective

・Development of two systems:
1) a system that makes proper use of the ‘Early earthquake warning’; and2) a system that does not depend too much on
the ‘Early earthquake warning’・Active promotion of infrastructure and house retrofitting

42

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Conclusions

What do I expect from the early
earthquake warning?
Encouragement for understanding and implementing
concrete countermeasures before the event especiallydisaster imagination capacity◆Early warning system can become catalyst
for promoting seismic retrofitting andreconstruction of weak structures◆Increase disaster imagination capacity→ Hard and soft countermeasures to create
disaster resilient “environment” and “people”
Promote 「Indirect plus」
Reduce 「Indirect minus」

Early Earthquake Warning System in Japan

Promote 「Direct plus」
Reduce 「Direct minus」

43

July 2008, Thailand

ICUS, IIS
Universityof TokyoThank you
Kimiro MEGURO

44

Joint Student Seminar on Civil Infrastructures

GEOPHYSICAL CHARACTERIZATIONOF GEO-MATERIALSGYE-CHUN CHO and TAE-HYUK KWON
Department of Civil and Environmental Engineering
KAIST, Korea
gyechun@kaist.edu
kikig@kaist.ac.kr

ABSTRACT
Elastic and electromagnetic waves can be used to gather important
information about geo-materials. To facilitate geophysical characterizationof geo-materials, their fundamental properties are discussed andexperimental procedures are presented for both elastic and electromagnetic
waves. The shear wave measurements centered on monitoring changes in
effective stress during consolidation, multi-phase phenomena related tocapillarity, microscale characteristics of particles, and small-strain stiffnessof jointed rock masses related to joint conditions. The electromagnetic wave
measurements focused on stratigraphy detection in layered soils, theestimation of the void ratio and its spatial distribution, conduction in
unsaturated soils, nucleation of gas hydrate in pore spaces and weak zone
prediction in water-saturated rock masses. Compressional wave
measurements were used to capture hydrate formation in pore spaces and to
identify the shotcrete bonding state to a hard rock surface. Experimental
results suggest that mechanical waves allow studying contact phenomena,
the evolution of interparticle forces, bulk stiffness of pore fluids anddiscontinuity characteristics, while electromagnetic waves give insight into
the characteristics of the pore fluid phase and its spatial distribution.

1. INTRODUCTION
Small perturbation elastic and electromagnetic waves allow characterizationof geo-materials (i.e., soils and rock masses) without causing any permanent
effect (Santamarina et al. 2001, 2004). The physical interpretation of thesemeasurements (i.e., elastic and electromagnetic wave parameters) permits
inferring important information on the geo-materials and its physicalprocesses. Soils are particulate and multi-phase materials (i.e., air, fluid andsolid mineral). Rock masses are discrete media involving intact rocks,
joints, joint-filling materials, and water. Their properties and the interaction
among distinct phases can be captured using elastic and electromagnetic
wave parameters. This interpretation can be local or global, depending on
the scale of interest.
In order to apply geophysical characterization method to particulatematerials and discrete media, their fundamental properties are first discussed,
and then diverse applications including laboratory experimental procedures

45

July 2008, Thailand

and analytical models are presented for both elastic and electromagnetic
waves.

2. CHARACTERISTICS OF GEO-MATERIALS
2.1 Soils as particulate materials
The properties of particulate materials are governed by their physicalcharacteristics (e.g., geometry and strength of grain), effective stress,
presence of water (e.g., saturated or unsaturated condition), global void ratio(or porosity), temporal scales (e.g., drained or undrained condition), andspatial scales (e.g., fabric, packing) among others. These factors are
discussed to gain insight into the fundamental behavior of particulatematerials.
2.1.1 Microscale characteristics
The geometry of a soil grain reflects its chemical composition andformation history and affects soil behavior. Both size and shape are required
to properly describe the particle geometry. Particle size is the most relevant
parameter in assessing the relative balance between skeletal, electrical andcapillary forces between neighboring particles. Particle shape ischaracterized by three dimensionless ratios: sphericity, roundness androughness (Wadell 1932, Powers 1953, Krumbein and Sloss 1963, Barrett1980). Sphericity indicates whether one, two, or three of the particle
dimensions are of the same order of magnitude, and it is defined as thediameter of the largest inscribed sphere relative to the diameter of thesmallest circumscribed sphere. Roundness is quantified as the averageradius of curvature of surface features relative to the radius of the maximum
sphere that can be inscribed in the particle. Roughness describes the surface
texture relative to the radius of the particle. Convex particle surface profiles
can be approximated with a Fourier series or through optical microscopy.
Image analyzers can be used to automate particle sizing and shapedetermination (e.g., Yudhbir and Abedinzadeh 1991, Kuo et al. 1996). The
relevance of particle shape on soil strength is intuitively accepted andsupported by some experimental evidence. For example, the interparticle
friction angle increases with angularity and surface roughness (Frossard
1979, Santamarina and Cascante 1998, Santamarina and Cho 2004, Cho etal. 2006).
2.1.2 Effective stress
When a soil is saturated, the granular skeleton and the pore fluid share
the total boundary stress σ applied to a soil mass. The portion carried by theskeleton is the effective stress σ′. If the pore fluid pressure is u, the effective
stress σ′ is equal to the total stress σ minus the pore fluid pressure u (i.e., σ′= σ - u; Terzaghi’s effective stress concept). Following Coulomb’s failure
criterion (i.e., τ = σ′ tan φ, where φ is the friction angle of the soil), the shear
strength τ is a function of the effective stress σ′ (Heyman 1997). In addition,
stiffness (at small or large strain) and dilatancy (i.e., the volume change

46

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

upon shear may be either positive or negative; Schofield 1998) are related tothe effective stress.
2.1.3 Presence of water
Contrary to saturated soils, the presence of two non-miscible fluids
adds interfacial tension (i.e., surface tension) and capillary forces between
particles. This is typically the case between air and water, or water andorganic fluids. In unsaturated soils, the negative pore-water pressure inmenisci that exists due to capillarity at particle contacts increases theinterparticle forces, changes the small-strain stiffness, and alters the soil
strength (Fredlund and Rahardjo 1993, Cho 2001). All forms of conduction
and diffusion processes depend on the size and connectivity of the menisci
as well. Furthermore, the equivalent effective stress due to capillary forces
increases with decreasing degree of saturation, decreasing particle size (orincreasing specific surface), and increasing coordination of the particles(Cho and Santamarina 2001).
2.1.4 Void ratio
The void ratio (or porosity) is affected by the grain size distribution of
the soil and the particle shape. In general, well-graded soils produce higher
maximum densities while platy particles (i.e., clay) have a wider range ofdensities. According to the critical state soil mechanics approach, theundrained response of a soil is uniquely related to the initial void ratio(Roscoe et al. 1958, Schofield and Wroth 1968). For example, a lower void
ratio for a given soil renders a higher undrained shear strength. Thus, theundrained shear strength can be estimated from critical state parameters andthe initial void ratio.
2.1.5 Spatial variation
The spatial variability of soil parameters affects the macroscale soil
response. The effects of spatial variability on soil behavior have beenstudied in the context of geoprocesses such as soil liquefaction (Popescu andPrevost 1996, Popescu et al. 1997), slope instability (Yong et al. 1977,
Tonon et al. 2000), seepage (Griffiths and Fenton 1993, Fenton and
Griffiths 1996), and settlement (Paice et al. 1996). The inherent variabilityof soil properties in natural soil deposits can be very large. Spatial
variability has an important effect even in relatively small laboratory
specimens as well. The presence of multiple internal spatial scales is
associated with the development of multiple temporal scales for processes
taking place within the medium such as consolidation, permeability,
fluctuation of the capillary fringe, chemical diffusion, aging, creep andcementation (Santamarina et al. 2001). For example, the excess pore waterpressure that builds up during shear is determined by the rate of pore waterpressure generation versus the rate of pore water pressure dissipation. In
turn, both mechanisms are related to the spatial variation of void ratio(Dobry and Petrakis 1990). The internal structure of a soil can becharacterized using statistical parameters that summarize the average
property (e.g., mean) and the variability (e.g., standard deviation). These
parameters are used in the common case of particle size distribution but inthe less frequently assessed case of void ratio distribution. However, theGeophysical Characterization of Geo-Materials

47

July 2008, Thailand

spatial distribution of the local values can play a critical role in global
behavior, even in soil deposits that have the same global statistics (Cho2001).
2.2 Rock masses as discrete media
Rock as an engineering material is heterogeneous and often
discontinuous. These discontinuities are ubiquitous in a rock mass in theform of bedding planes, joints, shear zones, and faults; and can be sizedfrom a small crack (e.g., fissures) to a planar crack (e.g., joints, bedding
planes) which are up to 10 m. The properties of a rock mass are governed by
the characteristics of intact rock, joint conditions (e.g., roughness, apertureand filling materials), orientation of joints, stress state, and presence ofwater among others. Particularly, the presence of joints and theircharacteristics determine the behavior of the rock mass, including its
strength, stiffness, and all forms of conduction and diffusion–hydraulic,electrical, chemical and thermal. Thus, these factors are influential to theproperties of mechanical and electromagnetic wave propagation in rockmasses.

3. MECHANICAL AND ELECTROMAGNETIC WAVES
3.1 Mechanical wave
3.1.1 Wave propagation in particulate materials
Small-strain deformations in particulate materials take place atconstant fabric (small-strain conditions apply when the strain level is lower
than the elastic threshold strain). Under this condition, the soil deformation
observed at the macroscale is the integration of contact level deformations.
The stiffness of a soil is dependent on the nature of individual particle
contacts, the interparticle contact area, and the interparticle forces (e.g.,skeletal, electrical, and capillary forces). The Hertz-Mindlin model ofcontact behavior shows that the stiffness of two spheres in contact is nonlinear and stress-dependent. The simplest expression is of the form (Stokoe
et al. 1991, Santamarina et al. 2001)
Vs =

⎛σ '
⎞
= α ⎜ mean ⎟ρ⎝ 1kPa ⎠

G

β

(1)

where Vs is the shear wave velocity [m/s], G is the shear stiffness[kPa] in the small-strain regime, ρ is density [kg/m3], the α-factor is theshear wave velocity at 1 kPa, σ’mean is the mean state of effective stress inthe propagation plane (e.g., σ’mean = (1+Ko) σ’v/2 for the σ’h = Koσ’v
condition where σ’h is the horizontal effective stress, σ’v is the verticaleffective stress and Ko is the lateral earth pressure coefficient), and the βexponent reflects the sensitivity of Vs to changes in the mean state ofeffective stress in the propagation plane. The shear wave velocity inparticulate materials only depends on the effective interparticle contact

48

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

forces and the ensuing contact stiffness, but it is not affected by the bulk
stiffness of the pore fluid. For this reason, transverse S-waves (i.e., shear
waves) are preferred for the characterization of particulate materials ascompared to longitudinal P-waves (i.e., compression waves). In thefollowing section, shear waves are applied to characterize particulatematerials, concentrating on changes in effective stress during consolidation,
multi-phase phenomena related to capillarity, and microscale characteristicsof the particles.
3.1.2 Wave propagation in jointed rock masses
The mechanical characteristics and orientation of joints determine thesmall and large strain behavior of rock masses and all forms of conduction
and diffusion properties (Priest 1993, Guéguen and Palciauskas 1994,
Huang et al. 1995). In particular, while the state of stress has little effect on
the stiffness of intact rock, it exerts a predominant effect on the wave
velocity and attenuation in jointed rock masses (Goodman 1989, Fratta andSantamarina 2002, Zhao et al. 2006).
The wavelength λ is the length scale of the propagating wave. The
spacing between joints is a salient length scale in the rock mass, which is
Lmass=Lr+Lj. Lr is the thickness of the intact rock block and Lj is the apertureof the joint. Wave propagation in jointed rocks can be organized into two
extreme cases.
Short wavelength (λ≪Lmass). The short-wavelength or high-frequency
case applies when the wavelength is much shorter than the separation
between joints λ≪Lmass. A short-wavelength plane wave transmitting
normally to the layering crosses through each component as if in an infinite
medium, experiencing the material attenuation of the medium and a partial
transmission and reflection at interfaces. Both reflected and transmitted
components generated at an interface experience subsequent reflections andtransmissions at other interfaces. The transmitted wave experiences
dispersion and attenuation (Fratta and Santamarina 2002)..
The transmission coefficient depends on the relative mechanical impedance
between the rock blocks and the filling, and on the ratio between the
thickness of the joint, Lj, and the wavelength of the traveling wave within
the filling, λ=V/f. If the joint thickness is very small compared with thewavelength (λ≫LJ) and with the length of the rock block (Lr≫Lj; that is,
the joint ratio approaches η=0), the transmission coefficient theoretically
becomes T=1.0, and the wave does not detect the presence of the joint.
However, experimental data show that energy loss and time delay take placeat joints even in closed joints (Pyrak-Nolte et al. 1990a, 1990b).
Long wavelength (λ≫Lmass). Long-wavelength case applies when the
wavelength λ is much longer than the spacing between joints S. This is themost common situation in seismology and field seismic investigation[White, 1983] and can be considered as an equivalent continuum for the
problem of wave propagation (Fratta and Santamarina 2002). The groupvelocity in periodic, discrete media is a function of the ratio between the

Geophysical Characterization of Geo-Materials

49

July 2008, Thailand

wavelength λ and the internal spatial scale of the medium, which in this caseis the joint spacing S. If the velocity for an infinite wavelength is V∞, thenthe group velocity Vλ for wavelength λ can be estimated as (Brillouin 1946,
Santamarina et al. 2001):⎛ πS ⎞
Vgλ =V ∞ cos ⎜ ⎟
⎝ λ ⎠

(2)

Thus, a jointed rock mass is as a low-pass filter and the group velocity
tends to zero when λ→2S. The long wavelength approximation requires
λ/S>>2. Long-wave length propagation does not experience reflections atinterfaces because the wave travels through the medium as in a continuum
without noticing the presence of interfaces. However, losses in the two
media contribute to the total loss in the medium.
3.2 Electromagnetic wave
3.2.1 Electromagnetic properties in particulate materials
Small-perturbation electromagnetic waves propagate through the soil
mass without causing any permanent effect. The physical interpretation ofthese measurements permits inferring important properties about soil mass
including porosity, volumetric water content, pore fluid characteristics (e.g.,permittivity and ionic concentration), fabric anisotropy, and the interaction
among distinct phases in soils (for a detailed review see Santamarina et al.
2001).
There are three electromagnetic properties. The electrical conductivity
σ (or resistivity ρ = 1/σ) is a measure of charge mobility in response to anelectric field. Conductivity in wet particulate media reflects thecontributions of the particle conductivity (generally small), the bulk fluid
conductivity, and surface conduction due to the increased counter-ion
concentration in the double layer surrounding the particles. Thus, theconnectivity of phases is related to the conductivity of soil-water mixtures,
which allows the possible assessment of stratigraphy detection in layeredsoils and conduction in unsaturated soils.
The complex dielectric permittivity κ* is frequency-dependent, andinvolves both a real part κ' and an imaginary part κ" :

κ * = κ '+ j ⋅ κ "(3)

The real dielectric permittivity κ' represents the polarizability of thematerial, while the imaginary permittivity captures polarization losses κ" pol .
The measured effective imaginary permittivity κ"eff combines polarization
losses and Ohmic conduction σ losses,

50

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

κ "eff = κ " pol +

σ
ωε 0

(4)

where ε0 is the permittivity of vacuum (ε0 = 8.85⋅10-12 F/m). The
dielectric permittivity of soil-water mixtures depends on the type of soil,
including mineralogy and its specific surface, porosity, pore fluid
characteristics, the volumetric fluid content, and the frequency of theapplied electric field. Thus, the dielectric permittivity of a soil is closely
associated with water content and void ratio.
Finally, the complex magnetic permeability μ* captures themagnetizability and the magnetization losses of the material. Most soils are
non-ferromagnetic, therefore, the complex permeability μ* is thepermeability of vacuum μ0 (μ* = μ0 = 4π⋅10-7 H/m). In the following section,
electromagnetic waves are applied to characterize particulate materials.

4. APPLICATIONS OF GEOPHYSICAL CHARACTERIZATION
4.1 Effective stressParticle deformation at contacts (exacerbated by angularity), bendingof platy particles, and contact slippage (facilitated in smooth particles)
determine the deformability of soils under zero-lateral strain Ko-loading. In
order to evaluate the changes in effective stress during consolidation,oedometric tests (K0 condition) were performed on undisturbed Pusan clay
specimens (D50 = 7 μm, Gs = 2.71). Piezoelectric bender elements (i.e.,bimorphs; series-type) were mounted on the top and bottom platens to send
and to receive shear waves. Travel time of bender elements’ tip-to-tip
distance was measured and shear wave velocity is calculated. The volume
change of each specimen (diameter = 7.5 cm) was measured at various
vertical effective confinements in the range of approximately 1 to 400 kPa.
Figure 1 shows the variation of void ratio and shear wave velocity
versus consolidation time under a certain loading where the hollow circles
are experimental test results and the solid line is a trend. It seems that theshear wave velocity enables estimating the change in effective stress (i.e.,
dissipation of excessive pore water pressure) during consolidation. When asoft soil in situ is subjected to additional loading, its consolidation process
can be monitored using in-situ shear wave velocities.
Figure 2 shows the variation of void ratio and shear wave velocity
versus applied vertical stress. As the vertical stress increases, the void ratio
decreases and the shear wave velocity increases. The empirical relation ofshear wave velocity to applied vertical stress is documented in Figure 2(b),where φ is the interparticle friction angle (20° for the soil used).
Experimental results suggest that the shear wave velocity is uniquely related
to the state of stress, so that it can be used to assess the state of stress and itschange during the consolidation process.

Geophysical Characterization of Geo-Materials

51

July 2008, Thailand

160

Shear wave velocity, Vs [m/s] 1

Void ratio, e

1.4

1.3

1.2

140

120

100

1.1
0.1

1

10

100

1000

0.1

10000

1

10

100

1000

10000

Time [min]Time [min](a) Void ratio(b) Shear wave velocity

Figure 1: The void ratio and shear wave velocity versus consolidation time.
300
Shear wave velocity [m/sec]

Void ratio, e

2

1.5

1

0.5

0

100
200
300
400
Applied vertical stress [kPa]500(a) Void ratio200⎡ (1 + K 0 ) ⋅ σ ' v ⎤V s = 26 ⎢
⎥⎦
2
⎣

100

0 . 38K 0 = 1 − sin φ
0

0

100
200
300
400
Applied vertical stress [kPa]500(b) Shear wave velocity

Figure 2: The variation of void ratio and shear wave velocity versus appliedvertical stress.
4.2 Multi-phase Phenomena – Capillarity
In order to explore the implications of capillarity on stiffness inunsaturated particulate materials, drying tests were performed while
monitoring the saturation of the specimen with shear waves and electricalresistivity. A drying cell was made for this purpose (Details can be found in
Cho and Santamarina 2001 and Choi et al. 2004). The cell consists of anacrylic glass shell, an aluminum top platen, and an aluminum bottom platen.
The metal platens, which were connected to a LCR meter with wires, acted
as electrodes. Piezoelectric bender elements were mounted on the top andbottom platens to send and receive shear waves. This configuration allowed
continuous monitoring of the shear wave velocity and the electromagnetic
properties of specimens made of two soils. The LCR meter was used to gain
low frequency electromagnetic properties (e.g., resistance and reactance; theresistivity ρ can be calculated from the relation of ρ = R⋅L/A where R is theresistance, L is the specimen length, and A is the specimen area).

52

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

The tested soil was Keum River sand (D50 = 0.4 mm, uniform grainsize). The void ratio of the natural sand specimen was e = 0.76. The drying
cell for the soil specimens was suspended with a flexible wire inside an
incubator. The wire acted on an external scale that allowed the weight of thespecimen to be monitored, in order to compute the water content or the
degree of saturation. The temperature was kept constant at 50°C to avoid
changes in surface tension (surface tension decreases with increasing
temperature), and changes in confinement due to the expansion andshrinkage of the cell.
The measured shear wave velocity is plotted versus the corresponding
degree of saturation in Figure 3a. As the degree of saturation decreases fromthe saturated condition (S=100%) to the dry condition (S=0%), the shear
wave velocity increases continuously and shows no drop even at theperfectly dry condition, S=0% (Figure 3a). The zero degree of saturation is
confirmed by measuring the weight of the specimen after further drying athigh temperature (i.e., 100°C). The jump in shear wave velocity near S=0%
may be explained by stiffening mechanisms, such as fines migration to thecontacts of the larger particles, salt precipitation, and bonding due to ion
sharing. The similarity between the grain-size distribution plot and the shear
wave velocity plot is noticeable, highlighting the importance of the grainsize distribution on capillarity (see also Cho and Santamarina 2001).
In Figure 3a, point A is related to the air-entry value in the waterretention curve, which is the air phase breaks through the pore structure.
Large pore size governs the magnitude of the effective stress increase inhigh degrees of saturation. A uniform coarse-grained soil like the Keumriver sand tends to have a uniform-sized pore distribution, rendering the
gentle slope between points A and C. Point B indicates the transition zone
between the funicular (continuous water) and pendular (discontinuous
water) stages. Salt precipitation is expected as drying proceeds from thepoint C to the peak velocity at S = 0%. Experimental results suggest that theshear wave velocity captures the change in effective stress caused bycapillarity in unsaturated soils. This is particularly valuable in the pendular
regime where direct measurement of the negative pore-water pressure is not
feasible.
The resistivity (ρ) of the specimen is plotted versus the corresponding
the degree of saturation. When the degree of saturation decreases, theresistivity increases. The resistivity in the sand specimen increases
continuously with the decrease of water content (Figure 3b). The air-entry
value in the water-retention curve cannot be detected from resistivity
measurements, suggesting that the percolation of the air phase minimallyaffects the variation in resistivity. The resistivity-degree of saturation trend
is represented by a bi-linear line. The transition point D, at the intersectionof these two lines, is related to the percolation threshold, which is thecritical water fraction when the continuous phase becomes disconnected (i.e.,completion of pendular stage). The resistivity of soil-water mixtures isdependent on the degree of saturation, thus, the presence of water and theGeophysical Characterization of Geo-Materials

53

July 2008, Thailand

interaction between the water and soil particles in unsaturated media can beassessed using electromagnetic measurements.

10000

140

C

Resistivity [Ω∙m]

Shear wave velocity, Vs [m/s]

160

B
A

120

100

80

1000

D
100

10

1
0

20

40

60

80

100

0

Degree of saturation, S [%](a) Shear wave velocity

20

40

60

80

100

Degree of[%][% ]
Degreeof saturation
saturation(b) Electrical resistivity

Figure 3: Shear-wave velocity and electrical resistivity versus the degree ofsaturation during drying process of Kuem River sand.
4.3 Microscale characteristics – Particle ShapeSpheres with rough surfaces may have the same average contact area
as spheres with smooth surfaces, but rough surfaces are composed of manysmall asperities which can be modeled as cones. The stiffness of a conicalcontact is smaller than that of a spherical contact because an equivalent
increase in contact area requires more strain in a conical contact. As theforce between particles increases, the global spherical shape of the roughparticles begins to have a greater influence on the contact behavior than the
shape of the asperities, and the stiffness of the rough particle contacts
approaches that of a smooth particle. When many different sized asperities
are present on particle surfaces, only the largest ones are initially in contact,
therefore the actual contact area is lower than in the spherical case and thestiffness is lower (Santamarina and Cascante 1998, Yimsiri and Soga 1999).
Non-spherical, platy or ellipsoidal particles tend to favour theformation of inherently anisotropic fabrics and enhance the development ofstress-induced fabric anisotropy. The small-strain longitudinal and shear
stiffness reflect fabric anisotropy even under isotropic confinement. The
effect of particle orientation on shear wave velocity anisotropy underisotropic effective stress conditions is explored with two sets of specimens;
one made of mica flakes and the second prepared with rice grains(Santamarina and Cho 2004). Preferential particle alignment during
specimen preparation is readily confirmed in both cases. Experimental
results show that the shear wave velocity is higher when the direction ofwave propagation is parallel to the main axis of the particles, as compared tothe shear wave velocity in specimens where particles are aligned in the
direction of particle motion; the ratio VS-HV/VS-VH=1.3-to-1.5 in mica, and
VS-HV/VS-VH= 1.11 in rice (here the first index represents the direction of

54

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

wave propagation, the second index represents the direction of particle
movement, H is the horizontal direction, and V is the vertical direction) .
Pennington et al. (1997) report similar ranges in shear wave velocity
anisotropy in natural clays.
In order to explore the effect of global particle shape on the smallstrain behaviour, the shear wave velocity was measured on specimens madeof 16 sands with varying confining stresses. The oedometeric cell was used
for this purpose. Based on experimental results, the α-factor and the βexponent of Equation. (1) for each sand are determined by best-fitting thedata. Figure 4 shows the effect of particle shape on the shear wave velocity(where Ir is the irregularity defined as the average of sphericity androundness). In general, a robust inverse trend between the α-factor and theβ-exponent is observed in all types of soils: the stiffer the particles and thedenser the packing, the higher the value of the factor α and the lower the βexponent. Experimental results show that as particle shape becomes nonspherical and angular (Ir<0.5), the exponent β increases with decreasing α
factor. Thus, angular and non-spherical particles increase the sensitivity ofstiffness to the state of stress (refer to Cho et al. 2006 for more detailed
experimental data and descriptions).
0.5

Ir < 0.5 (non-spherical & angular)

β -exponent

0.4

Ir > 0.5 (spherical & round)

0.3
0.2
0.1

line: β = 0.36 - α/700
points: experimental data

0
0

50

100

150

200

α -factor [m/s]

Figure 4: The effect of particle shape on the shear wave velocity. The α-βtrend line is from Santamarina et al. (2001).
4.4 Stratigraphy - layer detection
A simple and effective technique is proposed to assess the spatial
variability (including layers) of sandy or clayey soil specimens with submillimetric resolution. The technique involves a needle-size probe that ispushed into the soil and permits measuring the local electromagnetic
properties of the medium along its path. The device and its calibration are
described in detail in Cho et al. (2004). The probe is a thin, stainless steel
needle, with an insulated wire inserted into the needle, and bonded to it withepoxy resin to form a coaxial probe. The tip of the probe is ground andpolished to form a sharp edge (25 degrees – single side). The dimensions ofGeophysical Characterization of Geo-Materials

55July 2008, Thailand

the probe are: probe diameter is dprobe = 2.10 mm, the wire diameter is dcore= 0.63 mm, and the probe length is 152 mm. The electromagnetic properties
were determined by measuring either the resistance R and the reactance X,
or the magnitude of the impedance |Z| and the phase angle θ (Z* = R + j⋅X)
using an HP-4192A Hewlett Packard low frequency impedance analyzer.
The ability of the electrical needle probe to resolve interfaces was
explored using sandy and clay specimens. Two tests were performed. The
first test involves a three-layer sand specimen made of Ottawa 20-30 sand
(D50 = 0.72mm; round), Ticino sand (D50 = 0.58mm; angular), and Ottawa
F-110 sand (D50 = 0.12mm; round) prepared by water pluviation. The needle
probe was gradually pushed into the specimen. The variation in thecorrected impedance with depth is shown in Figure 5(a). The three sandlayers are distinguished. The layers with larger particles (i.e., Ottawa 20-30
and Ticino sands) exhibit higher variance than the layer composed ofsmaller particles (i.e., Ottawa F-110).
The second test involved kaolinite (D50 = 5μm; LL = 50), Georgia red
clay (D50 = 7μm; LL = 40), and bentonite (D50 = 0.6 μm; LL = 250), eachindividually mixed with water at the liquid limit. Then, the water-clay
mixtures were stacked in a glass container and stored for a month to reduce
the possible contrast in electro chemical potential between the layers. The
variation in impedance with depth was determined with the needle probe(Figure 5b). The three clay layers are clearly distinguished. Bentonite shows
the lowest variability in the impedance. The characteristic internal lengthscale of soils can be determined by the needle probe, for example, thedistance between the thin layers in varved clays.
0

0

Water

Water

-1

-1

Ottawa 20-30

Depth (cm)Depth (cm)-2
-3

Ticino-4Kaolinite-2

Georgia red clay
-3

-5

Bentonite-4

Ottawa F-110

-6
-7

-5
0

5

10

15

20

25

30

Magnitude of impedance lZl [kΩ ](a) Sand specimen

0

2

4

6

8

Magnitude of impedance lZl [kΩ ](b) Clay specimen

Figure 5: Stratigraphy detection with the electrical probe at fr = 1 MHz.
4.5 Void ratio and its spatial distribution
Void ratio (i.e., porosity) is an important soil property within relation
to strength, conduction, and diffusion processes. Numerous attempts havebeen made to evaluate pore size distribution and its spatial variability, using
techniques such as mercury porosimetry, gas adsorption, X-ray scattering(Mitchell et al. 1976, Mulilis et al. 1977), small-angle neutron scattering,

56

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

computed tomography based on X-ray absorption (Desrues et al. 1996), andimaging techniques using cross-sections of impregnated soils (Jang et al.
1999). The mercury porosimetry and gas adsorption techniques are limited
to small-size specimens. The X-ray scattering technique, which is anindirect method, requires careful calibration and usually gives qualitative
information rather than quantitative information. The computed tomographymethod requires careful calibration and inversion techniques to smooth thecontrast in mass density. Imaging techniques using cross-sections ofimpregnated soils are practical in sandy soils, however, its implementation
is destructive and the same specimen cannot be measured both before andafter testing.
A simple and effective technique is proposed herein to assess thespatial variability of sand specimens with sub-millimetric resolution. The
technique involves the needle-size probe described in the previous section.
The computation of the real relative dielectric permittivity κ′ (for simplicity,
the term permittivity is used hereafter) from the measured impedance values|Z*meas| is based on equivalent circuit elements (this approach is valid in the
low frequency range, i.e., below 10 MHz). The electrical response of a soil
is modeled as a ‘lossy dielectric’, which involves a resistor and a capacitor
in parallel. Therefore, the impedance corresponding to the soil Z*soil is:
Z

*
soil

⎡ 1
⎤
=⎢
+ jωCsoil ⎥⎣ Rsoil⎦−1(6)where Rsoil and Csoil are the resistance and the capacitance of the soil
respectively, j is the imaginary unit, and ω is the angular frequency.
The void ratio can be estimated from the electromagnetic
measurements. In its simplest form, the permittivity κ′mea of saturated soils
can be expressed in terms of a volumetric average. Thus, the void ratio e insaturated soils is:e=κ' mea − κ' s
κ' w − κ' mea(7)

where κ′w is the permittivity of water and κ′s is the permittivity of soil
particles. The value of κ′w = 78.5 is used for water and κ′s = 6 for themineral that makes the particles. Permittivity increases with void ratio insaturated soils.
Ottawa F-110 sand (D50 = 0.12 mm, emax = 0.848, emin = 0.535) wasused to explore specimen preparation effects. Six triaxial specimens with anominal diameter of 75mm and height of 150mm were prepared. A circularaluminum split mold and a 0.033cm thick latex membrane are used to formand hold the specimen. The specimens were prepared by air pluviation,
moist tamping, and water pluviation procedures.

Geophysical Characterization of Geo-Materials

57

July 2008, Thailand

Before triaixial testing, the electric needle probe was graduallyinserted into the specimens to estimate spatial variability. The complex
impedance Z* was measured every 0.5 mm, corrected for stray parameters,
and permittivity was calculated. Finally, the local void ratios were estimatedfrom the permittivity. The results are shown in Figure 6 (other data can befound in Cho et al. 2004). It is observed that the specimen prepared by the
moist tamping method has the highest variation in void ratio, while thespecimen prepared by water pluviation shows the lowest variation.
Comparing the result from standard undrained triaxial tests, it is noticeable
that the spatial distribution of void ratio affects the undrained strength, thatis, the higher the variation in local void ratio, the lower strength.
0-2eave = 0.826(Moist tamping)

-2

-4

-6

-6

-6

Depth (cm)

-4

-8

-8

-8

-10

-10

-10

-12

-12

-12

-14

-14

-14
0.6

0.7

0.8

Void ratio

0.9

1eave = 0.694(Water pluviation)-2-4

Depth (cm)Depth (cm)00eave = 0.801(Air pluviation)

0.6

0.7

0.8

0.9

1

Void ratio

0.6

0.7

0.8

0.9

1

Void ratio

Figure 6: Void ratio variability for different specimens (fr = 1MHz,
voltage= 1V). The value eave is the global void ratio of the specimen and theparenthesis represents the specimen preparation procedure.
4.6 Pore fluid composition - gas hydrate formation
Mechanical wave and electromagnetic wave capture thecharacteristics of pore fluids including volumetric composition of pore
fluids and phase transformation of pore fluids. (i.e., gas hydrate formation,water freezing, or vaporization during drying). This section proposes thewave-based measurements of gas hydrate-bearing sediments. Nucleation
and accumulation of gas hydrate in sediments are monitored during hydrate
formation.
Experiments were designed to investigate the formation anddestabilization of gas hydrate-bearing sediments. All the experiments wereconducted in a cylindrical cell (i.e., volume 3.17 cm3; internal diameter 6.35mm; height 100 mm), instrumented to measure temperature, pressure,electrical resistance and P-wave velocity. The cell was submerged in a bath,the temperature of which was controlled between 20°C and -10°C by
circulating coolant from a cooler. The fine-grained sands (Ottawa F110sand; uniform grain size; mean diameter = 120 μm grain size) were58

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

compacted in the reaction cell at a porosity φ = 0.397 and no effective stress
was applied.
First, the sediment specimen was fully saturated with water andpressurized to 4 MPa. Liquefied CO2 was injected with approximate 5 MPaof pressure, and pore water in the specimen was saturated with dissolved
CO2 molecules chemically diffused from one end of the specimen. Afterseveral days, CO2 dissolution terminated, as determined by monitoringpressure, and the sediment sample in the reaction cell was thereafter
stabilized for 24 hours. Then, under an initial pressure of 4.7 MPa,
sediments were cooled to 0.5°C. Temperature, pressure inside the systemand electrical resistance were monitored during the formation process. Pwave velocity was periodically measured.
Figure 7 shows the evolution of temperature, pressure inside thesediment specimen, VP, and resistance during cooling. Phase transformation(hydrate nucleation) began at approximately 2°C, showing a temperature
jump due to release of heat by exothermic reaction and a sudden drop ofpressure at roughly 230 min after the start of cooling. Resistance insediments suddenly jumped due to decreased connectivity of water resulting
from hydrate nucleation. VP of the sediments remains almost constant until
solid hydrate crystals nucleate. As soon as the hydrates started to form inpores, an apparent increase of VP (from ~1650 m/s to ~1740 m/s, as shownin Figure 2) was noted, as the bulk modulus of the hydrate crystals is higher
than that of the pore water. In addition, as the hydrate crystal growth
proceeded by diffusion of dissolved CO2 and pore spaces were filled withsolid hydrate (hydrate accumulation). VP continued increasing up to almost
2700 m/s.

Figure 7: Monitoring of formation of CO2 hydrate in sediments.

Geophysical Characterization of Geo-Materials

59

July 2008, Thailand

Several field and laboratory test results with synthetic hydrates
support the pore filling hypothesis for the hydrate growth habit. In turn,compressional wave is more sensitive to capture the hydrate formation
rather than shear wave, since an increase in bulk stiffness of pore fluids
occurs prior to the shear stiffness of the skeleton during the formation of asmall fraction of hydrate in pores. Electrical resistivity also provides
complementary information, particularly on the pore fluid composition andhydrate quantity.
4.7 Shear wave propagation in jointed rock masses - stress state andjoint condition
The stress level and joint condition affect shear wave propagation
through regularly jointed rock masses. In this section, measurements ofvelocity and attenuation are conducted using a resonant column device
designed for jointed rocks.
Shear waves are not affected by geometry; consequently, the torsional
shear wave velocity and attenuation measured in a cylindrical bar apply tothe infinite medium (Kolsky 1963). Furthermore, there is no geometricattenuation in bars. Based on these observations, we developed a torsional
resonant column device to study long-wavelength shear wave propagation
through jointed rocks. The cylindrical column is formed by verticallystacking rock disks on top of a high impedance steel base in order to create afree-fixed system. A light metal cap sits on top of the rock column, and theaxial load is hung from the top cap by means of a rod that runs along acentral hole drilled in each rock disc. Two accelerometers are mounted on
the top cap to detect torsional motion. They are placed at diametrically
opposite locations and their axes are aligned normal to the radius of thecolumn. Figure 8 shows the jointed rock column and peripheral electronic
devices.
Accelerometer
Torsional excitation(quasi-static)

Conditioner

Signal filter

Accelerometer
Rock disc

Oscilloscope
Steel baseRod
Weights

Figure 8: The rock resonant column testing device.
The torsional excitation is created by suddenly releasing the column
from a quasi-static deformation enforced at the top of the column, allowing

60

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

it to vibrate freely. The average strain level was kept below γ = 10-5 in all
tests. Each column is subjected to staged loading to the desired maximum
normal stress (400 to 700 kPa). Wave propagation measurements are
conducted at each stress stage during loading, and repeated during
unloading after reaching the maximum load.
The signals obtained from the two accelerometers are added to cancel
the flexural response. The combined signal is then transformed to thefrequency domain to obtain the resonance spectrum. The resonant frequency
fn and the damping ratio D are recovered from the resonance spectrum. The
wavelength λ is four times the column length L (λ = 4L) in first mode freefixed resonance. Therefore, the torsional shear wave velocity is Vs=4Lfn.
Damping ratio D, spatial attenuation αD and quality factor Q are related as
D = αDλ/2π = 1/2Q for low-loss conditions. Therefore the propagation
parameter αD [1/m] can be readily computed from the measured values of D.
The propagation velocity increases as the normal stress increases.
Furthermore, the wave velocity through the rock mass decreases
considerably in the presence of filling material in the joints. The response
becomes more stress-dependent as the joint thickness increases, and in thepresence of clayey rather than non-plastic gouge material.
The long-wavelength approximation λ>>S is the most common
situation in seismology and field seismic investigation (White 1983).
Hertzian-type contact phenomena suggest a power function for the joint
stiffness kj as a function of the normal stress σn:⎛ σn ⎞
k j = ψ⎜⎟⎝ 1kPa ⎠ζ(8)where the ζ exponent captures the stress sensitivity of the joint
stiffness, and ψ [GPa/m] is the joint stiffness at σn=1 kPa. Therefore, theshear wave velocity in the rock mass Vrm can be computed:
⎛
⎞
⎜
⎟
1 ⎜ 1
1
⎟
Vrm =
+
ζ ⎟
2
⎜
ρrm Vr ρr⎛ σ ⎞⎜S ⋅ ψ ⎜ n ⎟ ⎟⎟⎜⎝ 1kPa ⎠ ⎠
⎝

−1

(9)

This equation captures the effect of joints on rock mass softening. The
joint parameters ψ and ζ reflect joint surface properties, gouge type andthickness. They can be determined by measuring the shear wave velocity inthe rock mass at different stress levels (Note: the mass density of the rockmass ρrm and the intact rock wave velocity Vr and density ρr must be
determined separately).

Geophysical Characterization of Geo-Materials

61

July 2008, Thailand

In analogy to wave propagation in soils, we explore the possibility ofusing a simpler expression to relate the propagation velocity in the rockmass to the applied normal stress,⎛ σ ⎞Vrm = α ⎜ n ⎟⎝ 1kPa ⎠β(10)

In this case, α is the wave velocity in the rock mass subjected to σn= 1kPa, and β describes the stress-sensitivity of wave velocity in the rock mass.
The inverted α-β values are plotted in Figure 9; for comparison, the α-βpairs for a wide range of soils are superimposed on Figure 9 as well. The
stress-dependent wave propagation velocity through jointed rock masses iswell captured by a power-type relation.
Parameters α-β for rock masses tend to cluster above the cluster forsoils. Therefore, wave velocity through jointed rock masses is higher than insoils at the same state of stress. Softer and thicker joints lead to lower
stiffness at σn = 1 kPa (either factor ψ or α) and higher stress sensitivity(either exponents ζ or β). In general, there is an inverse relationship between
stiffness at σn = 1 kPa and stress-sensitivity, both in the case of joint
stiffness parameters ψ-ζ (Equation 3) and rock mass velocity parameters αβ (Equation 5).
Various joint properties are reproduced in the experiments to study
their effect on shear wave propagation. Experimental results show that shear
wave velocity increases with increasing normal stress, joint spacing andjoint bonding, but it decreases with increasing joint opening and plasticity of
the joint filling. The opposite trends are observed between attenuation androck mass parameters. Well-matched grooved surfaces, as in slickensides,
are less detrimental to stiffness and attenuation than mismatched roughsurfaces. Analytical models that take into consideration the stress-dependent
stiffness and frictional loss in joints and the stress-independent properties ofrock blocks properly model experimental observations and permit extracting
joint properties from rock mass tests data. Results highlight the prevalentrole of joints on propagation velocity and attenuation in jointed rock masses.

62

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

0.5

Soil data collected by the authors
Rock mass-this study
Rock mass-Fratta & Santamarina (2002)
0.4

β−exponent(Planar aluminum)

Gouge↑

0.3

Intact Vs↑
Bonding↑Roughness↑

0.2

Spacing↑
0.1

0
0

100

200

300

400

α−factor [m/s]

Figure 9: Parameters for the velocity–stress power relation (after Fratta
and Santamarina 2002). Data shown as open circles were gathered with awide range of soils; the regression line β = 0.36 - α/700 applies to thesedata.
4.8 Anomaly detection in rock masses - tunnel head prediction
In viewpoint of geotechnical engineering, the prediction of anomaly
presence in subsurface and the estimation of its position, size and state play
an important role in designing structural foundations and characterizing
their overall mechanical behaviors. Particularly, during the construction oftunnels, occurrence of poor rock masses at the tunnel face is a significant
threat. However, the prediction of a weak zone remains as a unsolved
problem to engineers related to underground space design and construction.
Thus, this section presents an enhanced algorithm which effectively detects
anomalies in particulate materials using an electrical resistivity survey.
The current of the particulate material with a spherical weak zone asshown in Figure 10 can be expressed using Coulomb’s law and Gauss’ law:
l −r

l+r

0

l −r

I = ∫ σ pm E pm ⋅ π ldl + ∫ σ w Ew ⋅ α ldl
l +r

∞

l −r

l +r

+ ∫ σ pm E pm ⋅ (π − α ) ldl + ∫ σ pm E pm ⋅ π ldl(11)where α denotes sin-1(r/l), r is the radius of the weak zone, σw is the
conductivity of the weak zone and σpm is the conductivity of the particulatematerial.
Given that resistances are measured for each sensor configuration, thecoordination of the sensors and the conductivity of the material; unknown
parameters such as the size, conductivity and location of the anomaly can beobtained through an inversion algorithm (see Ryu et al. 2008 for moredetails). A series of experimental tests was performed on anomalies thatwere different in terms of size, location, and type in order to verify the

Geophysical Characterization of Geo-Materials

63

July 2008, Thailand

developed algorithm. A comparison of the predicted and measured values
shows that anomalies can be detected effectively using the electricalresistivity–based enhanced algorithm developed in this study.
E+q

θ

Ez

E-q
l
+q

-q

θ
x
L

Figure 10: Electric field configuration for detection of spherical weak zone
from tunnel face.
4.9 Shotcrete bonding state evaluation using the impact-echo method
Shotcrete is the general term for the cement, sand and fine aggregate
concrete that are applied pneumatically and compacted dynamically underhigh velocity. Shotcrete is an important primary support for tunneling inrock. The bonding state of shotcrete on excavated rock surfaces is a core
issue in the safe construction and maintenance of tunnels. Although
shotcrete may be applied well initially onto excavated rock surfaces, it isaffected by blasting, rock deformation and shrinkage and can debond fromthe excavated surface, causing problems such as corrosion, buckling,
fracturing and the creation of internal voids. The effective non-destructive
method is proposed to evaluate the tunnel shotcrete bonding state using theimpact-echo (IE) method. Various bonding conditions (i.e., fully bonded,
debonded, and void) were simulated using numerical and experimental
models. The signals obtained from the numerical and experimental IE tests
were analyzed at the time domain, frequency domain, and time-frequency
domain (i.e., the Short-Time Fourier transform).
ImpactImpactShotcrete

Shotcrete

Rock

Rock

(a) Fully bonded condition

64(b) Debonded condition

Joint Student Seminar on Civil Infrastructures

ICUS Report 30
ImpactShotcreteRock(c) Void condition

Figure 11: Graphical description of wave propagation depending on the
shotcrete bonding state.
The typical results of wave propagation (i.e., acceleration) in the finite
elements are shown in Figure 11 for different bonding states (0.00018sec
after impact). In the case of the fully bonded condition (Figure 11a), thestress wave transmits through the shotcrete and hard rock layers and only
slightly reflects from the interface between the shotcrete and hard rocklayers. In the case of a debonded condition (Figure 11b), the stress wave
transmits part of the way through and partly reflects from the interface,resulting in some part becoming entrapped in the shotcrete layer.
Additionally, in the case of a void condition (Figure 11c), the stress wave
does not transmit through the interface and completely reflects from theinterface, resulting in the entire energy in this case becoming entrapped in
the shotcrete layer. This is similar to an ideal free-free boundary condition.
Both numerical and experimental results suggest that the bonding stateof shotcrete can be evaluated accurately through distinct changes in the peak
amplitude in a time domain analysis, through changes in the resonancefrequency and geometric damping ratio in a frequency domain analysis, andthrough changes in the contour shape and correlation coefficient in a timefrequency analysis.

5. CONCLUDING REMARKS
Soils are particulate and multi-phase materials, thus, their behavior isgoverned by microscale characteristics, effective stress, the presence ofwater, global void ratio, and temporal and spatial scales. Rock masses are
discontinuous media, and their behavior is determined by the characteristics
of intact rock, joint conditions (e.g., roughness, aperture and fillingmaterials), orientation of joints, stress state, and presence of water among
others. These properties can be effectively characterized using wave-based
techniques. Experiments were performed using both elastic andelectromagnetic waves to facilitate the application of wave-based techniques
to characterize geo-materials. The shear wave measurements centered onmonitoring changes in effective stress during consolidation, multi-phase
phenomena related to capillarity, microscale characteristics of particles, andsmall-strain stiffness of jointed rock masses related to joint conditions. The
electromagnetic wave measurements focused on stratigraphy detection inGeophysical Characterization of Geo-Materials

65July 2008, Thailand

layered soils, the estimation of the void ratio and its spatial distribution,
conduction in unsaturated soils, nucleation of gas hydrate in pore spaces andweak zone prediction in water-saturated rock masses. Compressional wave
measurements were used to capture hydrate formation in pore spaces and to
identify the shotcrete bonding state to a hard rock surface. The main
conclusions from this study are as follows:y When a clay is subjected to a Ko-loading, the shear wave velocity is
uniquely related to the state of stress, so that it can be used to assess thestate of stress and its changes during the consolidation.
y In unsaturated soils, changes in stiffness are related to changes ininterparticle forces such as capillarity, bonding due to ion sharing, buttresseffects due to fines migration and cementation due to salt precipitation.
Shear waves permit studying the evolution of effective interparticle forcesin unsaturated soils. This is particularly valuable in the pendular regime
where direct measurements of the negative pore-water pressure are notfeasible.
y As the degree of saturation decreases, the shear wave velocity andresistivity in unsaturated soils increase continuously and show no drop at theperfectly dry condition. The relation of shear wave velocity and resistivity
to the degree of saturation is unique for each soil, underlining theimportance of water content on soil characterization.
y The pore fluid and the mineralogy of grains govern the resistivity ofsaturated soils, and the amount of water in the soil mass and its connectivity
controls resistivity changes in unsaturated soils.
y Angular and non-spherical particles increase the sensitivity ofstiffness to the state of stress, rendering high β-exponents.
y The electrical needle-size probe can be used to detect interfaces inlayered soils and to effectively assess the spatial distribution of void ratio insaturated soils and other properties in laboratory specimens, with submillimetric resolution. The local measurements of complex impedance
permit assessing the spatial variability of either porosity, fluid resistivity(i.e., water content), or both.
y P-wave velocity and electrical resistivity capture the nucleation ofgas hydrate in sediment pores and provide a means of monitoring theincrease of hydrate saturation.
y Shear wave velocity in jointed rock masses increases withincreasing normal stress, joint spacing and bonding, and decreases withincreasing thickness and plasticity of the joint filling. The rougher the joint,
the less sensitive to the stress the wave velocity becomes. On the other hand,shear wave damping in jointed rock masses decreases with increasing
normal stress and with rough joints, and exhibits a large increase when
joints are filled with gouge materials.

66

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

y The joint characteristics are directly related to the criteria for a rockmass classification system. The effect of joint conditions and stress levels
on wave velocity can be reflected in rock mass characterization using
seismic data so that wave-based rock mass characterization secures morereliability.
y Given that resistances are measured for each sensor configuration,
the coordination of the sensors and the conductivity of the material;
unknown parameters such as the size, conductivity and location of theanomaly can be obtained through an inversion algorithm.
y The shape of the time-frequency domain contour plot, the value ofthe correlation coefficient, and the geometric damping ratio gathered fromthe impact echo method give valuable information to assess the tunnel
shotcrete bonding state in situ.

ACKNOWLEDGEMENTS
This research work was funded by the Brain Korea 21 Project in 2008. We
wish to express our sincere appreciation to the organizing committees forproviding the opportunity to undertake this research work.

REFERENCES
Barrett, P.J., 1980. The shape of rock particles, a critical review,
Sedimentology, V. 27, pp. 291-303.
Brillouin, L., 1946. Wave propagation in periodic structures, McGraw-Hill.
Cho, G.C., 2001. Unsaturated soil stiffness and post-liquefaction shear
strength, Ph.D. Thesis, Georgia Institute of Technology, p. 288.
Cho, G.C. and Santamarina, J.C., 2001. Unsaturated particulate materials Particle-level study, Journal of Geotechnical and Geoenvironmental
Engineering, ASCE, V. 127, No. 1, pp. 84-96.
Cho, G.C., Lee, J.S., and Santamarina, J.C., 2004. Spatial variability insoils: high resolution assessment with electrical needle probe, Journalof Geotechnical and Geoenvironmental Engineering, ASCE, V. 130,
No. 8, August, pp. 843-850.
Cho, G.C., Dodds, J., and Santamarina, J.C., 2006. Particle shape effects on
packing density, stiffness, and strength: natural and crushed sands,
Journal of Geotechnical and Geoenvironmental Engineering, ASCE,
V. 132, No. 5, May, pp. 591-602.
Choi, J.S., Song, K.I., Cho, G.C., and Lee, S.W., 2004. Characterization of
unsaturated particulate materials using elastic and electromagnetic
waves, Key Engineering Materials, V. 270-273, pp. 1653-1658.
Desrues, J., Chambon, R., Mokni, M., and Mazerolle, F., 1996. Void ratio
evolution inside shear bands in triaxial sand specimens studied bycomputed tomography, Géotechnique, V. 46, No. 3, pp. 529-546.

Geophysical Characterization of Geo-Materials

67

July 2008, Thailand

Dobry, R. and Petrakis, E., 1990. Micromechanical modeling to predict sanddensification by cyclic straining, Journal of Engineering Mechanics,
ASCE, V. 116, No. 2, pp. 288-308.
Fenton, G.A. and Griffiths, D.V., 1996. Stochastics of free surface flow
through stochastic earth dam, Journal of Geotechnical Engineering, V.
122, No. 6, pp. 427-436.
Fratta, D., and Santamarina, J.C., 2002. Shear wave propagation in jointed
rock: state of stress, Géotechnique, V.52, pp. 495–505.
Fredlund, D.G. and Rahardjo, H., 1993. Soil mechanics for unsaturated soils.
Wiley Inter-Science, New York, p. 517.
Frossard, E., 1979. Effect of sand grain shape on interparticle friction:
indirect measurements by Rowe’s stress dilatancy theory,
Géotechnique, V. 29, No. 3, pp. 341-350.
Griffiths, D.V. and Fenton, G.A., 1993. Seepage beneath water retaining
structures founded on spatially random soil, Géotechnique, V. 43, No.
4, pp. 577-587.
Goodman, R.E., 1989. Introduction to rock mechanics, 2nd ed., John Wiley& Sons.
Guéguen, Y., and Palciauskus, V., 1994. Introduction to the physics of rock,Princeton University Press.
Heyman, J., 1997. Coulomb’s Memoir on Statics, An Essay in the History of
Civil Engineering, Imperial College Press, p. 212.
Huang, T. H., C. S. Chang, and Z. Y. Yang, 1995. Elastic moduli forfractured rock mass, Rock Mechanics and Rock Engineering, V.28, pp.
135–144.
Jang, D.-J., Frost, J.D., and Park, J.Y., 1999. Preparation of epoxy
impregnated sand coupons for image analysis, Geotechnical Testing
Journal, GTJODJ, V. 22, No. 2, pp. 147-158.
Kolsky, H., 1963. Stress waves in solids, Dover.
Krumbein, W. C. and Sloss, L. L., 1963. Stratigraphy and Sedimentation,
Second Edition, W. H. Freeman and Company, San Francisco, p. 660.
Kuo, C.-Y., Frost, J.D., Lai, J.S., and Wang, L.B., 1996. Three-dimensional
image analysis of aggregate particle from orthogonal projections,
Transportation Research Record, No. 1526, pp. 98-103.
Mitchell, J.K., Chatoian, J.M., and Carpenter, G.C., 1976. The influences ofsand fabric on liquefaction behavior, Report No. TE 76-1, U.S. ArmyEngineer Waterways Experiment Station, University of California,
Berkeley.
Mulilis, J.P., Seed, H.B., Chan, C.K., Mitchell, J.K., and Arulanandan, K.,
1977. Effects of sample preparation on sand liquefaction, Journal of
the Geotechnical Engineering, V. 103, No. GT2, February, pp. 91-108.
Paice, G.M., Griffiths, D.V., and Fenton, G.A., 1996. Finite element
modeling of settlements on spatially random soil, Journal of the
Geotechnical Engineering Division, ASCE, V. 122, No. 9, pp. 777779.
Pennington, D.S., Nash, D.F.T., and Lings, M.L., 1997. Anisotropy of shear
stiffness in Gault clay, Géotechnique, V. 47, no. 3, pp. 391-398.
Popescu, R. and Prevost, J.H., 1996. Influence of spatial variability of soil
properties on seismically induced soil liquefaction, Uncertainty in the
Geological Environment: from theory to practice, Proceedings of68

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Uncertainty ’96, edited by Schackelford et al., Geotechnical Special
Publication No. 58, Vol. 2, pp. 1098-1112.
Popescu, R., Prevost, J.H., and Deodatis, G., 1997. Effects of spatial
variability on soil liquefaction: some design recommendations,Géotechnique, V. 47, No. 5, pp. 1019-1036.
Powers, M.C., 1953. A new roundness scale for sedimentary particles,
Journal of Sedimentary Petrology, V. 23, No. 2, pp. 117-119.
Priest, S. D., 1993. Discontinuity analysis for rock engineering, Chapman &Hall.
Pyrak-Nolte, L.U., L.R. Myer, and N.G. Cook, 1990a. Transmission ofseismic wave across single natural fracture, J. Geophys. Res., V. 95, pp.
8617–8638.
Pyrak-Nolte, L.U., L.R. Myer, and N.G. Cook, 1990b. Anisotropy in seismic
velocities and amplitudes from multiple parallel fractures, J. Geophys.
Res., V. 95, pp. 11345–11358.
Roscoe, K.H., Schofield, A.N., and Wroth, C.P., 1958. On the yielding ofsoils, Géotechnique, V. 8, pp. 22-53.
Ryu, H.H., Cho, G.C., Sim, Y.J., and Lee, I.M., 2008. Detection of
anomalies in particulate materials using electrical resistivity survery enhanced algorithm, Modern Physics Letters B, V. 22, No. 11, pp.
1093-1098.
Santamarina, J.C. and Cho, G.C., 2004. Soil behaviour: the role of particle
shape, The Skempton Memorial Conference, Thomas Telford, Vol. 1,
pp. 604-617.
Santamarina, J.C. and Cascante, G., 1998. Effect of surface roughness onwave propagation parameters, Géotechnique, V. 48, No. 1, pp. 129136.
Santamarina, J.C., Klein, K.A., and Fam, M.A., 2001. Soils and Waves –Particulate Materials Behavior, Characterization and Process
Monitoring, John Wiley and Sons, LTD, p. 488.
Santamarina, J.C., Rinaldi, V.A., Fratta, D., Klein, K., Wang, Y.H., Cho,
G.C., and Cascante, G., 2004. The properties of near-surface soils in
relation to elastic and electromagnetic wave parameters, Chapter inPhysical properties of near-surface materials.
Schofield, A.N., 1998. Don’t use the C word, Ground Engineering, August,pp. 30-32.
Schofield, A.N. and Wroth, P., 1968. Critical State Soil Mechanics,
McGraw-Hill Book Company.
Stokoe, K.H., II, Lee, J.N.-K. and Lee, S.H.-H., 1991. Characterization ofsoil in calibration chambers with seismic waves, Proceedings of 1stInternational Symposium on Calibration Chamber Testing, Elsevier,Potsdam, New York, pp. 363-376.
Tonon, F., Bernardini, A., and Mammino, A., 2000. Reliability analysis ofrock mass response by means of random set theory, Reliability
Engineering and System Safety, V. 70, No. 3, pp. 263-282.
Wadel, H., 1932. Volume, shape, and roundness of rock particles, Journal of
Geology, Vol. 40, pp. 443-451.
White, J.E., 1983. Underground sound: Application of seismic waves,
Elsevier.

Geophysical Characterization of Geo-Materials

69

July 2008, Thailand

Yimsiri, S. and Soga, K., 1999. Effect of surface roughness on small-strain
modulus:micromechanics
view,
Pre-failure
Deformation
Characteristics of Geomaterials: Proceedings, 2nd International
Symposium, Torino, Italy; edited by M. Jamiolkowski, R. Lancellotta,
and D. Lo Presti, 597-602
Yong, R.N., Alonso, E., and Tabba, M.M., 1977. Application of risk
analysis to the prediction of slope stability, Canadian Geotechnical
Journal, V. 14, pp. 540-553.
Yudhbir, and Abedinzadeh, R., 1991. Quantification of particle shape andangularity using the image analyzer, Geotechnical Testing Journal,
GTJODJ, V. 14, No. 3, pp. 296-308.
Zhao, J., X.B. Zhao, and J.G. Cai, 2006. A further study of P-wave
attenuation across parallel fractures with linear deformational
behavior, Int. J. Rock Mech. Min., V. 43, pp. 776–788.

70

Joint Student Seminar on Civil Infrastructures

TREND OF TRAFFIC ACCIDENTS
AND ITS CHARACTERISTICS IN JAPANSHINJI TANAKAInternational Center for Urban Safety Engineering,
Institute of Industrial Science, The University of Tokyo, Japan
stanaka@iis.u-tokyo.ac.jp
ABSTRACT
Traffic accident is one of the most serious risks in our daily life
compared with other natural disasters. This paper reviews the trend of
traffic accidents and its characteristics in the case of Japan. Japan becomesa relatively safe country in the world after long efforts to improve traffic
safety which keep the number of fatalities decreasing, but the number ofaccidents is not decreasing, remains high. Specifically, traffic accidents ofelderly people, pedestrians and at intersections are major issues currently.
These trends are explained with some figures, and some research works toaddress traffic safety are also introduced.

1. INTRODUCTION
We tend to think that traffic accident is a rare, unlikely and unlucky event.
However, even if you yourself have not experienced any traffic accidents inyour life before, you may easily find somebody who has experienced it inyour family, relatives and friends. Actually, the probability of one person
encountering fatal traffic accident in his/her life is 0.5%, the probability
becomes 53.4% for injury accidents and much more for non-reported
accidents. Thus, traffic accident is not a rare event, but an immediate riskfor everybody.
There were two serious traffic accidents in Japan in 2006. One took
place in an intercity motorway in the middle of a rainy night. A truck
slipped, spun and stopped with its front turned back blocking thecarriageway. Thereafter, 20 vehicles collided with it one right after the other.
As a result of this accident, 4 fatalities and 10 injuries occurred.
The other tragic accident occurred similarly in the night. A drunk
driver collided with a car, at the top of an over-sea bridge, from behind. The
car, carrying the five members of a family, dived into the sea due to theimpact and the 3 children in the rear seat were killed. This accident, widely
covered by the media, resulted in a revision of the Road Traffic Law totoughen the penalty for drunken driving.

71July 2008, Thailand

Figure 1: Serious traffic accidents in 2006
When we think of disasters, we easily picture natural disasters, such as
earthquakes, typhoons, floods, tsunamis and so on. All of them seriously
impact our society at once and therefore it is of course quite important to
prepare for them. However, if we asses the severity of disasters by the
number of deaths, traffic accidents result in much more fatalities than any
natural disasters every year in Japan as shown in Figure 2 (although there isa decreasing trend). And, we all remember the Hanshin-Awaji Earthquake
Disaster or the Sumatra Tsunami Disaster very clearly, but few of us
remember yesterday’s fatal traffic accidents. Traffic accidents should be
regarded as man-made disasters affecting urban safety. We should start to
tackle it to realize a comprehensive urban safety.
(persons)

18,00016,00014,00012,000Traffic Accidents

10,0008,000
6,000

Natural Disasters

4,000

Fire

2,000
0
1970

1975

1980

1985

1990

1995

2000

2005

Figure 2: Number of fatalities caused by disasters in Japan

72

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

2. TRAFFIC ACCIDENTS IN THE WORLDFirst, let us review the situation of traffic accidents in the world. As for thenumber of fatalities by traffic accidents in different countries, the top threedeadliest countries are China, India, and the United States. The former two
are the most populated and the last one is the most motorized country.
However, if you see the same numbers in relative terms, i.e. number offatalities per 100 thousand persons as shown in Figure 3, the situation
becomes different. China and India are now ranked in the middle, and themost dangerous countries are South Africa, Malaysia and Russia. On theother hand, northern European countries such as Netherland, Sweden, theUnited Kingdom and Norway, which are regarded as keen on safetymeasures, are in the safest group. Japan is a relatively safe country next tothem. Actually, the Japanese government set a goal in 2003 “to reduce
traffic fatalities to less than 5,000 a year and to realize the safest trafficsociety in the world”. If the number achieves this, then “the safest” might
become true. Looking at these figures, Japan seems to have fewer problemson the traffic safety issue.
(persons)

30.0

25.0

20.0

15.0

10.0

5.0

No UK
rw
a
J y
D apa
Sw enm n
itz arer k
Ge lan
rm d
a
Fi ny
n
Au lan
st d
ra
l
C ia
hi
na
In
C dia
an
a
Fr da
an
ce
Ne
w I
Ze ta
al ly
an
d
Sp
a
Ko in
re
a
U
G SA
re
e
Sa Mon ce
ud go
i A lia
ra
b
Ru ia
s
M
So a sia
ut lay
h si
Af a
ric
a

Ne
th
er
l
Sw anded
en0.0

Figure 3: Number of fatalities per 100 thousand persons

3. TRAFFIC ACCICENTS IN JAPAN
3.1 Overall trend
Then, is everything going well in Japan? Figure 4 shows the trend of
traffic accidents, fatalities and injuries in Japan. There was a peak in 1970,
when the number of fatalities was 16,775. This serious situation was often
called “traffic war”. After that, the government and the police made a lot ofefforts to reduce traffic accidents by, for example, providing sidewalk or
cross-over bridges for pedestrians, putting on traffic signals at intersections,obligating seatbelt fastening etc. Vehicle manufacturers also improved theirTrend of Traffic Accidents and its Characteristics in Japan73

July 2008, Thailand

products recently by equipping airbags, impact absorption bodies and so on.
Thanks to these countermeasures, the number of fatalities reduced
drastically to 5,744 in 2007, which is about one third of the peak value.
However, if you see the number of injuries or accidents, they havebeen not decreasing or stable in the last 30 years. This is one recent trend of
traffic accidents in Japan. Of course, as the volume of vehicles’ mileage isalso growing rapidly, it is not easy to reduce the number of traffic accidents.
Therefore, we need some other countermeasures to realize “the real safest
traffic” or “zero-accidents society”.
1400(persons)
18000(thousand persons)

16,77516000

num of injuries

1200

14000

num of accidents

1000

12000
800

10000

600

8000

num of fatalities

6000

5,744 (2007)

400

4000
200

2000
0

0
1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

Figure 4: Trend in the number of traffic accidents in Japan
3.2 Accidents by age groups
Next, let us see more specific problems. Figure 5 shows the numberof fatalities counted by age groups. The dominant age group is “65 andolder”, which accounts for 44.2% of fatalities. (Young people group was
worse in the 80s but it has improved nowadays.) Actually, the fatality ratioof elderly people in traffic accidents is extremely high compared with otherage groups as shown in Figure 6. This means, traffic accidents involving
elderly people is likely to become fatal ones. Also, Japanese society itself isaging more and more, therefore, the number of licensed drivers of 65 years
old and older is about 8 million today and will double to 17 million in 2030.
This transition may cause more serious problems.

74

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

3500(persons)

3000

65 and older(44.2%)

2500
2000
1500
1000
500
0
1980

1985

1990

1995

2000

2005

50-59 (12.8%)
16-24 (12.2%)
30-39 (8.6%)
40-49 (7.4%)
60-64 (7.4%)
25-29 (4.8%)
15 and younger(2.5%)

Figure 5: Fatalities by age group
2.50

(%)

2.00
1.50
1.00
0.50
0.00
15 and 16-24 25-29 30-39 40-49 50-59 60-64 65 andyoungerolder

Figure 6: Fatality ratio by age group
3.3 Accidents by transportation modes
Figure 7 shows the fatalities by transportation mode. Here, the largest
is in vehicles and the second is pedestrians. Actually, the percentage ofpedestrian fatalities out of the total is increasing from 2000. And, thepercentage of elderly people (65 and older) is also increasing.
others15 (0.2%)
pedestrian2,203(28.6%)

bicycle916(11.9%)

Total
7,702
(2003)

vehicle3,182(41.3%)

motorcycle
1,386(18.0%)

Figure 7: Fatalities by transportation mode

Trend of Traffic Accidents and its Characteristics in Japan75

July 2008, Thailand

As a result, the graph of fatalities by age groups and transportation
modes (Figure 8) suggests that elderly pedestrians are at significantly highrisk. The second and the third highest are also elderly people in vehicles oron bicycles. From these results, we can understand that traffic safety
countermeasures especially for elderly people, and pedestrians are highly
required.

(persons)

Figure 8: Fatalities by mode and age group
3.4 Types of accidents
Then, what types of accidents are most serious? Figure 9 shows thetypes of accidents by severity, that is, fatality, severe injury and light injury.
From this, we can see that; pedestrian, single and head-on accidents aremajor fatal accidents. Rear-end accidents is the largest light injury accidents.
Intersection head-on is relatively high in all categories. We need different
types of countermeasures depending on those accidents types.
vehicle related

non-vehicle

vehicle - vehicle

fatality
8,746

severeinjurysingle head-on

pedestrianintersection
head-onturning

79,666light
injury1,189,621 0%

rear-end
20%

40%

60%

others80%

100%

Figure 9: Types of accidents by severity

76

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

3.5 Location of accidents
As for accidents locations, Figure 10 shows the ratio of locations
where accidents occurred. Accidents at intersections occupy more than halfof total accidents, then accidents in straightway is about 40% and the rest isin other locations. As intersection accidents are likely to include not only
vehicles but also pedestrians or bicycles, countermeasures at intersections
are urgently required.
Other
22,876(2.6%)

Straightaway
366,162(41.3%)

Total Numberof Accidents
886,864(100%)

Intersection
497,826(56.1%)

Figure 10: Locations of accidents
3.6 Causes of accidents
Figure 11 shows a survey result investigating causes of accidents.
The largest is “delay in recognition”, the second is “errors in judgment” andthe third is “errors in operation”. Those three causes can be regarded as“Human errors” and they occupy three quarters of the accidents causes. The
rest is “others” like speeding and drinking etc. Of course these traffic
violations should be controlled strictly, but we may also need to consider
some driver’s assistance system, such as ITS, to reduce accidents caused byhuman errors.

Others(speeding, drinking…)(25%)
Errors inoperations(12%)
Errors injudgment(16%)

Delays inrecognition
(47%)

Human
errors(75%)

Figure 11: Causes of accidents

Trend of Traffic Accidents and its Characteristics in Japan77

July 2008, Thailand

3.7 Social loss by traffic accidents
Finally, how much social cost or loss do traffic accidents cause? The
Cabinet Office in Japan conducted a research project to estimate the social
loss caused by traffic accidents. It classified the loss into five categories,that is, human loss, physical loss, business loss, public loss and nonmonetary loss. Here, human loss means medical care cost or salary loss,
physical loss means car / structure damages, business loss is caused byworker’s absence, public loss is the cost for ambulance, police and cleaning,
and non-monetary loss means mental loss like pain, sorrow and trouble.
According to the result, the total loss including non-monetary loss wasapproximately 60 billion USD in 2007 and the composition is shown in
Figure 12. Non-monetary loss occupies quite a large share (35%), whichcomes mainly from fatal accidents. Even though the number of fatalities
becomes less than 6,000, we have to continue efforts to reduce them so thatthe social loss is reduced, too.
If we see the monetary part by severity, then the loss due to injury
accidents especially lighter ones is the hugest because their number is quite
large. In any sense, those losses are enormous and continue every year.

Human loss
(14 bln USD)

Non-monetary loss
(20 bln USD)

Physical loss
(17 bln USD)
Public loss
(10 bln USD)
Business loss
(1 bln USD)

Figure 12: Composition of social loss caused by accidents

4. RESERCHES FOR TRAFFIC SAFETY
To solve the problems mentioned above and to improve the traffic safety,
we need researches from the viewpoint of traffic engineering. One of the
topics introduced here is about signal control improvement.
Generally in signal control, we need some clearance time (yellow andred signal) to clear the traffic from the intersection when the signal phaseschange. At this moment, a lot of traffic accidents like head-on, rear-end andpedestrian accidents happen. Therefore, the clearance time is one of the keys
to improve traffic safety in urban signalized intersections. We observed
actual traffic flows at several intersections using video cameras and78

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

examined whether the current signal settings are appropriate to ensure
traffic flows in different directions.
The same can be said on pedestrian signals. Currently, pedestriansignal clearance time (flashing signal) is determined by the half the crossing
road length and as a result a lot of pedestrians remaining on the road when
the signal turns to red. Here we also conducted field observations andanalyzed pedestrian walking behaviors, then discussed the feasibility of anew pedestrian signal control method to reduce the number of remaining
pedestrians on red.
We sometimes use a driving simulator to analyze driver’s behavior
when he is faced with a yellow signal and puzzled whether to go or not,which is called “dilemma situation”. As the driving simulator can record
precise data of vehicle and driver, we can analyze his/her behavior indetailed way, for instance reaction time, vehicle’s deceleration etc. After
doing this, we would like to propose an advanced signal control which
reduces such dilemma situation.

Figure 13: Driving simulator analysis

5. CONCLUDING REMARKS
Traffic accidents are the most important issue to be solved in transportation
problems, and will continue to be in the future. Japan’s efforts achieved a
considerable reduction in the number of traffic fatalities from the peak, butthere are still lots of casualties due to traffic accidents. Furthermore, there
are still many developing countries which do not have very basic traffic
safety facilities like pedestrian sidewalk and traffic signals. We must
continue looking for a better solution to achieve a safer traffic, and should
contribute to safety improvement in other countries with our experiences.

REFERENCES
Cabinet Office, White Paper on Traffic Safety in Japan
National Police Agency, Road Traffic Accidents Japan
Fire and Disaster Management Agency, Statistics on Natural Disasters
Japan Automobile Manufacturers Association, 2004, Measures for Safety
and Environment

Trend of Traffic Accidents and its Characteristics in Japan79

July 2008, Thailand

80

Joint Student Seminar on Civil Infrastructures

BOND STRENGTH OF CONCRETE
INTERFACE BY USING FRACTUREMECHANICES APPROACH
PISON UDOMWORARATAssistant Professor, Department of Civil engineering
King Mongkut’s University of Technology, North Bangkok
pisontit@hotmail.com
ABSTRACTThis paper proposes an evaluation of concrete bond strength based onenergy approach. A four-point bending test for determining the criticalenergy release rate or the interfacial fracture toughness is applied to two
types of test specimens, i.e., sandwich of steel-concrete-steel specimen andsteel-CFRP-concrete specimen. A combination of testing results and pathindependent J-integral of finite element model based on Virtual crack
extension method can be used to determine interfacial fracture toughness
effectively. Moreover, it is found out that the interfacial fracture toughnessof steel-concrete-steel specimen depends on surface roughness of steel
plates and has average fracture toughness of 26.78 J/m2 where steel-CFRPconcrete specimen has average fracture toughness of 106.96 J/m2.

1. INTRODUCTION
To evaluate bond strength at interfaces of two dissimilar materials,
experimental methods of evaluations shall be broadly grouped in two
categories. The first category attempts to deduce the interface energy
through the observed propagation of a pre-existing flaw or crack. The
second attempts to measure direct quantities such as normal stress, shear
stress from the experiment without considering a pre-existing flaw.
Shortcomings found from the first category, is due to its complexity in
expression while the second category is a lack of applicability in case ofshear stress and normal stress existences simultaneously. The first category
seems to meaningfully characterize the bond behavior rather than the second
category when combining of both stresses. To deal with two dissimilarmaterials, interfacial fracture problems are inherently mixed mode, i.e.,
mode 1 and mode 2 that are very difficult to define by stress intensity
factors of the interfacial crack. Therefore, strain energy release rate, G, isusually used as a fracture parameter for interfacial mechanics. Since thestrain energy can be seen as finite value and a problem of oscillatory
singularity near the crack tip is avoided.
In this study, a four-point bending test has been proposed to evaluate
steel-to-concrete and carbon fiber reinforced polymer (CFRP)-to-concretebond strength. The bond strength are presented in terms of fracture energy

81July 2008, Thailand(strain energy release rate) by varying the surface roughness of the steel
plates for steel-to-concrete specimens. Likewise, the bond strength of
CFRP-to-concrete specimens are presented in terms of fracture energy byvarying the lengths of pre-existing cracks. Next, finite element analysis
based on J-integral is also carried out to verify the strain energy release rateof bimaterial interfacial crack. In order to facilitate discussion and a
profound understanding, some fundamental concepts of the interfacial
fracture mechanics have been reviewed in the next section.

2. INTERFACIAL FRACTURE MECHANICS
As shown in Figure 1, when two isotropic materials with different elastic
properties are bonded together and contain any interfacial crack lengths. Ifthey are subjected to any load in x-y plane, such system with the stressconcentrations at directly ahead of interfacial crack tip ( θ = 0 ) will always
occur in two directions, so-called mixed-mode stress. The mixed-mode
stress is inherent of bimaterial and the interfacial crack will extend whensuch stress reaches to its limit.
2rθ
E2 ,ν2E1 , ν1

1

Figure 1: The interfacial crack
The relationship between stress and interfacial stress intensity factor
ahead of crack tip ( r ,θ = 0 ) was defined by Rice (1988) in terms of acomplex form as

Kr i εσ 22 + iσ 12 =(1)
2π r
where σ 22 = normal stress, σ 12 = shear stress, i = − 1 , and complex
stress intensity factor as K = K1 + iK 2 (Mode I, Mode II intensity
factor)ε=1 ⎛ 1− β ⎞⎟ln⎜
2π ⎜⎝ 1 + β ⎟⎠(2)The quantity ε is a measure of the elastic mismatch of the bimaterial
pair. If the two materials have identical elastic properties, or if they are
incompressible (ν 1 = ν 2 = 0.5 ) , then ε = 0 and the stress fields reduced to thosefor homogeneous material. Relative displacements at location behind crack
tip can be expressed in terms of the interface stress intensity factor as

82

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

δ 2 + iδ1 =(4 1/ E1 + 1/ E2) Κ rr(1 + 2iε ) cosh (πε )

iε

2π

(3)

Where δ 2 = vertical displacement = u 2 (r , θ = π ) − u 2 (r , θ = − π ) ,δ 1 = horizontal displacement = u 1 (r , θ = π ) − u 1 (r , θ = − π ) , E j = modulus ofelasticity, E j = E j for plane stress condition, E j = E j /( 1 −ν 2j ) for planestrain condition, and Dundur’s elastic mismatch parameter asβ =1 μ1 (1 − 2ν 2 ) − μ 2 (1 − 2ν 1 )2 μ1 (1 − ν 2 ) + μ 2 (1 − ν 1 )(4)

where ν = Poisson’s ratio, μ = shear modulus, subscript of 1 and 2
designated to above and bottom materials, respectively.
If ε ≠ 0 , then, the oscillatory singularity is existed at the crack tip.
Consequently, the relevant characterizing to stress distribution around crack
tip or crack surface displacement as r → 0 cannot be available. Thus, theuse of phase angle,ψ , arctangent of Mode II to Mode I intensity factor,
which is in character of mixed mode to interpret the crack tip stress, is suitas expressed below⎛ K2 ⎞⎟⎝ K1 ⎠

ψ = tan −1 ⎜(5)

⎛ Im Kr i ε ⎞= tan −1 ⎜iε ⎟⎝ Re Kr ⎠Without a physical meaning, the complex form of the phase angle
from equation (3), r i ε , could be substituted by a dimensionless complex
variable, λ iε as shown below⎛ Im K λ i ε ⎞iε ⎟⎝ Re K λ ⎠ψ = tan −1 ⎜(6)where λ = r / L , L = characteristic length such as crack length
Generally, factor toughness of dissimilar materials can be defined byeither interfacial stress intensity factor, K or strain energy release rate, G.
Strain energy release rate, G, is superior and broadly used for interfacial
crack toughness than stress intensity factor due to its simplicity. As from thestudy of Matos et al. (1989), Sun and Qian (1997), it was shown that theresults from their analysis based on energy method worked very well.
Besides, interfacial stress intensity factor, K, is directly related to energy
release rate. As suggested by Malyshev and Salganik (1965), strain energy
release rate can be expressed in terms of interfacial stress intensity factor as

Bond Strength of Concrete Interface by Using Fracture Mechanics Approach83July 2008, Thailand

well, and the interfacial crack will be formed as G = GC (strain energy
release rate reaches critical strain energy release rate) or K = K c whereG=(1 / E + 1 / E ) K
1

2

2 cosh (πε )

2

(7)

2

3. EXPERIMENTAL SETUP
3.1 Four point bending specimen

Generally, the study of interfacial crack requires either four-point
bend specimen or other test configurations, as shown in Figure 2. Because a
steady-state of strain energy release rate (independent of crack length) is
existed for crack propagation between inner loading points.

Figure 2: Four point bending specimen
The steady-state strain energy release rate can be calculated by theelementary beam theory by transforming the beam section as
G ss =

M 2 ⎛⎜ 1
1 ⎞⎟−2 EB ⎜⎝ I c I g ⎟⎠(8)

where M = Pd / 2 , E = elastic modulus, I c = moment of inertia ofcrack beam , I g = moment of inertia of uncrack beam , and B = widthof section.
3.2 Steel-concrete-steel specimens

Four point bending specimen (2 layers) was originally proposed byCharalambides et al. (1989) and Matos et al. (1989), in order to determine
fracture resistance and stress intensities between bimaterial interfaces bymeans of the J-integral together with the virtual crack extension method. In
this study, a modified four point bending specimen (3 layers, SteelConcrete-Steel) is introduced for determining interface fracture energy byadding additional steel plate layer at the top of concrete layer. Figure 3
shows a sketch of the modified four point bending specimen. An idea of
introducing modified bending specimen for steel-concrete-steel interfaces isthat concrete is brittle in nature and 2 layers simple four point bending

84

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

specimen may not induce cracking along the interfaces, because verticalcracking may occur in concrete layer prior to interface crack propagation.
Beside that bottom substrate needs to elastically bend until cracking at
interface occurs.
Notch

P/(2B)

P/(2B)

Auxiliary
plate

B
Concretet1
ht2

Substrate2a2cdFigure 3: Modified four point bending specimen
The test specimens were prepared by placing cement mortar between
two controlled roughness steel plates, i.e., 50 μm , 80 μm and 120 μm .
Steel substrate and auxiliary plates were designed to have the same
dimension 50×300×5.8 mm. All steel plates are made of SM400 steel classof which the elastic modulus is approximately about 210000 MPa. The
mechanical of the concrete mortar are listed in Table 1.

Table 1: Cement mortar mechanical properties
Mortarσc (MPa)
31.6

E (GPa)
19.89

ν
0.17

There are totally 15 specimens, i.e., 5 specimens for each surface
roughness 50 μm , 80 μm and 120 μm which are designated as R50, R80
and R120, respectively. Figure 4 shows experimental setup of the test
specimen. The distance between inner loading points 2c is 200 mm where
the distance between upper and lower loading points d is 30 mm. The load
was applied by displacement control method with very low speed of 0.1 mm
per minute.

Figure 4: Setup of the steel-concrete-steel test specimen

Bond Strength of Concrete Interface by Using Fracture Mechanics Approach85

July 2008, Thailand

3.3 Steel-CFRP-Concrete specimens

When concrete beam externally reinforced with the CFRP plate, itcannot be directly tested as in section 3.2 because of its relatively low
flexural stiffness of CFRP. A plate can be curved along with the deflectionof beam; concrete had ruptured before a plate debonded. To capably control
debonding, a new test configuration has been proposed in order to improve
flexural stiffness of the CFRP plate. In this study, steel plates with adimension of 12×50 mm. and 500 mm. in length, were bonded with CFRP
plate. Ten of specimens, as shown in Figure 5 and 6, concrete blocks of
50×100×150 mm. were bonded to the other face of CFRP. Before bonding
together, a vinyl tape was stuck to both ends of blocks with having 5-to-23mm. in length to initiate interfacial precracks. Figure 7 shows experimental
setup of the test specimen.

Figure 5: Four point bending test

Figure 6: Specimen preparation

Figure 7: Setup of the steel-CFRP-concrete test specimen

86

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Table 2 contains the properties of the CFRP and epoxy resin, relevantto this study. The products of CFRP and adhesive resin were provided by
the Sika (Thailand) Co., Ltd.

Table 2: Properties of CFRP and epoxy resin
Type
S512

Epoxy Sika
cabodur – 30

Adhesive

Width (mm)50

Static E-modulus (GPa)12.8

Thickness (mm)1.2

Adhesive Strength(MPa)

Elastic Modulus (GPa)177

Shear Strength (MPa)

4 (concrete
failure)15 (concrete
failure)

CFRP

4. FOUR POINT BENDING SPECIMEN TEST RESULTS

A typical load-displacement from the experiments is shown in Figure 8.
The experimental results evidently suggest that the graph consists of two
slopes. The point where the first slope changes to the second slope can be
defined as the initial crack extension point. The stiffness of the composite
drops down to be the stiffness of steel substrate. Therefore, critical load (Pcr)
corresponding to the constant energy release rate can be indicated.
5
4.5
4Composite
Stiffness

Load (kN )3.5

Substrate
Stiffness

3
2.5
2

Pcr

1.5
1
0.5
0

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

Displacement (mm)Figure 8: Typical load-displacement response
By substituting the critical load into equation (8), the critical strainenergy release rates, Gc, can be determined. Similarly, using equation (7),critical stress intensity factor, Κ c , can be determined. From the test results,
average energy release rates of steel-concrete-steel specimens are plotted asa bar chart as shown in Figure 9. The results indicate that the energy release
rate depends slightly on the plate surface roughness. The energy release rate

Bond Strength of Concrete Interface by Using Fracture Mechanics Approach87

July 2008, Thailand

increases as the roughness increases. However, the test results show a verysmall discrepancy for the roughness 50-120 μm . The average energy
release rate of steel-concrete-steel is about 26.78 J/m2.

Crictical energy release rate (J/m2)

40
35
30

28.7

26.7

25.0
25
20
15
10
5
0
R50

R85

R120

Specimen series

Figure 9: Average energy release rate of steel-concrete-steel specimens
with various surface roughness
Table 3 shows critical energy release rate, Gc, of steel-CFRP-concrete
specimens of various precrack sizes. The Gc are relatively equal and quite
constant along with the crack lengths. This means that steady-state of strainenergy release rate (independent of crack length) is existed for crack
propagation between inner loading points. The average energy release rateof steel-CFRP-concrete is about 106.96 J/m2.

Table 3: Critical energy release rate of steel-CFRP-concrete specimens
with various precrack sizes
Cracklength( mm.)(

Gc J / m2

)

5

9

13

17

21

23

Average103.91104.79105.5

107.99123.77116.39106.96

5. FINITE ELEMENT MODEL AND ANALYTICAL RESULTS

Finite element software so-called ABAQUS is used to determine J-integral
and crack surface displacement. As shown in Figure 10, a steel-concretesteel model mesh consists of 1250 eight-node plain strain biquadraticelements. At the area in vicinity of the crack tip, finite element meshes aremodeled by wedge shape eight-node singular elements. The singularelement is formed by the 8-node element by coalescing the three nodes tothe one at the tip, whilst a square root singularity in the strain field at the tip
is obtained by placing the first node away from that point at one quarter of88

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

the distance to the second point. Similarly, as shown in Figure 11, steelCFRP-concrete model consists 1563 elements: CFRP beam (transformed
section of CFRP-steel beam) and concrete block. Material properties
are: E s = 200 GPa , ν s = 0.30 , E FRP = 177 GPa , ν FRP = 0.30 , E c = 19.89 GPa ,and
ν c = 0.17 .

Figure 10: Finite element model for steel-concrete-steel specimen

Figure 11: Finite element model for steel-CFRP-concrete specimen
To extract mode mix fracture resistance, the numerical method isapplied in combination with crack surface displacement method proposedby Matos et al. (1989). The stress intensity factor can be determined byinversing Equation (3) as1
2⎡ (1 + 2iε cosh(πε ) E1 E2 ⎤ ⎛ 2π ⎞
− iε
K = ⎢
⎟⎟ x (δ y + iδ x )⎥ ⎜⎜4( E1 + E2 )⎣⎦⎝ x ⎠(9)

Where x is the distance from crack tip to any node on coordinate( − r , θ = 0 ). The variables in complex displacement term, ( δ y + iδ x ) , are theresults of FEM. Considering all rings surrounded the crack tip, G isdetermined by substituting K into equation (7). The G is then comparedwith J-integral among those rings of the biquadratic element mesh. The one
provides G equal to J-integral, parameters of such ring, i.e., x and δ , will
be chosen to calculate the phase angle as

Bond Strength of Concrete Interface by Using Fracture Mechanics Approach89

July 2008, Thailand

⎛ x⎞
⎟
⎝L⎠

ψ = φu + φc − ε ln ⎜(10)where L = crack length, φu = arctan(δ x / δ y ) , φc = arctan(2ε )Figure 12 illustrates energy release rate versus crack length from steelconcrete-steel finite element model as an example. Constant energy release
rate can be obtained while crack propagates in between inner loading
supports. Subsequently, the energy release rate from the finite element
analysis decreases with increasing in crack length. Figure 12 shows phaseangles plotted against crack lengths. It is found that phase angle slightly
increases along with crack length. The average phase angle of steelconcrete-steel specimen is approximately about 46°. Similar manner isapplied to determine average phase angle of steel-CFRF-concrete specimen
which is about 35°.

40

Energy Release rate J/m2

35
30
25
20
15
10

Inner loading
support

5
00

20

40

60

80

100

120

140

Crack length (mm)Figure12: Plot of energy release rate versus crack length

90

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

90
80
70
60

ψ = 46oPhase angle

50
40
30

Inner loading
support

20
10
00

20

40

60

80

100

120

140

Crack length (mm)Figure13: Plot of phase angle versus crack length

6. CONCLUDING REMARKSThis research presents a possibility to evaluate bond strength via the use ofenergy release rate. The results indicate that the steady-state of the energy
release rate is existent, therefore, the use of the energy concept tocharacterize the behavior of debonding is possible. According to the fracture
mechanics approach, fracture toughness representing by energy release rateis somewhat smooth, unique, and independent of phase angle. The criticalenergy release rate can be served as an indicator for bond strength criterion.
It is found out that the interfacial fracture toughness of steel-concrete-steel
specimen depends on surface roughness of steel plates and has averagefracture toughness of 26.78 J/m2 where steel-CFRP-concrete specimen has
average fracture toughness of 106.96 J/m2.

REFERENCES

Charalambides, P. G., Lund, J., Evans, A. G. and McMeeking, R. M., 1989.
A Test specimen for determination the fracture resistance ofbimaterial interfaces. Journal of Applied Mechanics, Vol. 56, 77-82.
Malyshev, B.M. and Salganik, R.L., 1965. The strength of adhesive joints
using the theory of crack. International Journal of Fracture, Vol. 5,
114-128.
Matos, P. P. L., McMeeking, R. M., Charalambides, P. G. and Drory, M. D.,
1989. A method for calculating stress intensities in bimaterial fracture.
International Journal of Fracture, Vol. 40, 235-254.

Bond Strength of Concrete Interface by Using Fracture Mechanics Approach91

July 2008, Thailand

O’Down, N. P., Shih, C. F. and Stout, M.G., 1992. Test geometries formeasuring interfacial fracture toughness. International Journal of
Solids Structures, Vol. 29, 517-589.
Rice, J.R., 1988. Elastic fracture mechanics concepts for interfacial cracks.
Journal of Applied Mechanics, Vol. 55, 98-103.
Sun, C.T. and Qian, W., 1997. The use of finite extension strain energy
release rate in fracture of interfacial cracks. International Journal of
Solids Structures, Vol. 34, 2595-2609.

92

Joint Student Seminar on Civil Infrastructures

Student Presentations

INTERMODAL MODE CHOICE BETWEENJAPAN AND RUSSIATOMOYA KAWASAKI and SHINYA HANAOKA
Tokyo Institute of Technology, Japan
tomoyakawasaki@gmail.com
hanaoka@ide.titech.ac.jp

ABSTRACT
For the first time in Japan-Russian trade history, in 2006, export
cargoes from Japan to Russia firstly overtook import of Japan from Russia
in monetary terms. This is due to the high economic growth as well as other
East European countries. Current dominant freight mode between Japanand Russia is maritime transportation (SEA), which is now saturated due toan excess in west bound (W/B) cargo volume. Under this circumstance,
there is a need to be considered whether other freight transport mode such
as Trans-Siberian Railway (TSR) and intermodal transport mode ofmaritime and air (SEA&AIR) can be a viable alternative mode in this routeand to develop freight mode choice model with the objective of identifying
which factors should be reformed so as to enhance other alternative modes.
Data on SEA&AIR transport characteristics from interview survey are
analyzed for the decision making in adopting an alternative mode of SEA.
The prime time of SEA&AIR service is from the late 1980s to the early
1990s due to the high fare of air transport (AIR). At the present time,
demand on SEA&AIR service significantly declines and is not expected torecover due to several reasons such as Economies of Scale (EOS), risk ontransshipment process, size of container, low fare of AIR and growth ofSupply Chain Management (SCM). Hence, it is clear that the SEA&AIR nolonger is suitable as an alternative mode of SEA. On the other hand, TSR
has a potential to be developed into a viable alternative, since there areseveral advantages of TSR such as leadtime, mass-transit, consistent
haulage by the same container and so on.
Mode choice model on international logistics is developed by using
the discrete choice model by Stated Preference (SP) method. The SPquestionnaire survey was conducted with five potential users (shippers) of
TSR in Japan. The results show that security factor receiving the highest
weight. From the study, it can be concluded that in order to secure the usersof TSR, it should be reformed with a security factor at its top priority.

93

July 2008, Thailand

1. INTRODUCTION
1.1 General
Recently, Trans-Siberian Railway (TSR) re-rises as Russian economy
has been better off in these years. According to the report of International
Monetary Fund (IMF), GDP growth rate of Russia in the year of 2007 is+7.6%. As a result of the above fact which trend might last for several years,
international trade in Russia has been activated especially in the west part ofRussia with Far East Asian countries. As for trade between Japan andRussia in the view of Japan, export in 2006 firstly overtakes import byapproximately US$200 million in the trading history between Japan andRussia.
Currently, cargoes between Asia and Russia is dominantly transported
by maritime transport (SEA) via the Suez Canal, which is overwhelming
other transport modes in terms of mode share. In 2001, cargo volume of
Asia-Europe route was recorded 6.4 million TEU/year. On the other hand,the use of rail transport including TSR from Asia to Russia in 2001 is
accounted only about 40-50 thousand TEU/year, which share is only lessthan 1%. Wang (2006) reports that as for cargo from/to Japan, it is estimated
10,000TEU/year in approximate value including cargoes via Pusan where
port is virtually hub port for TSR. In this way, South Korea positively uses
TSR; however, Japanese companies tend to use SEA rather than TSR. The
share rate of TSR use by country in 2006 is “South Korea : China : Japan =63 : 33 : 4”. Tsuji (2007) insists that the reason of low occupancy rate ofJapan towards TSR use is not only its performance but also “bad image”
towards TSR.
1.2 Purpose of the study
Although SEA is dominantly operated between Japan and Russia, sea
ports in Russia are suffered from lack of space and decrepit. Moreover, SEA
is now saturated by plenty of cargoes, thus, alternative freight transportmode of SEA is highly required to make haulage between Japan and Russia
facilitating. Under this circumstance, we consider that TSR may be acted as
an alternative transport mode of SEA. Tsuji (2008). Moreover, SEA&AIR,
being one of the intermodal transport modes, might also be one of thecompetitors of SEA since SEA&AIR has unique characteristics such as
short leadtime, enabling to manage uncertainty and so on although it takes
relatively high cost. However, there are unfortunately almost no summary
articles and reports of SEA&AIR, hence its characteristics, trend, advantage
and disadvantage are not identified so far. Therefore, to clarify thecharacteristics of SEA&AIR itself can be considered as a quite significant
work. In addition, shippers’ preference on mode choice which would affecton planning for constructing public facilities and infrastructure should beknown for making logistics network smooth, as well as for TSR’s strategy
such as price setting. Therefore, mode choice model between Japan andRussia is highly needed to examine for planning of logistics network.

94

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

2. FREIGHT TRANSPORT MODE BETWEEN JAPAN AND RUSSIA
2.1 SEA transportation
SEA transportation via Suez Canal (approximately 22,000km), is
generally shipped via port of Hamburg, Rotterdam, Finland or SaintPetersburg, and then, shipped again to the final destination, Moscow, which
totally takes approximately 35-40 days. Most of land haulage in Russia uses
railway instead of truck by the intention of the government of Russia. The
port of Saint Petersburg holds several problems as follows;-

Only a call at a port by vessels with icebreaker for freeze-up ispossible.
Since the depth of the water is not deep enough, large-sized
containership is not possible to call at a port.
Since there is only one arrival port in addition to recent increase incargo volume, congestion is chronically occurred.
Since a container terminal does not have hinterland, there is noenlarged space there.

Due to the above facts, operation of punctual shipment which is a
crucial attribute in the view of Supply Chain Management (SCM) is quitedifficult to conduct. In general, delay time on SEA from Japan to Moscow is
generally said to be approximately 5-7days.
2.2 Trans-Siberian Railway (TSR)
TSR, originated at Vladivostok bound for Moscow (9,297km), iscurrently connecting to Finland, and other East European countries. In
addition to east side of Russia, TSR also reaches the northeastern part ofChina, North Korea, Mongolia, Kazakhstan, and Uzbekistan with manybranch lines, and gauge size is occasionally different from other countries’
as shown in Table 1.
Table 1: Difference of gauge size by country
Gauge Class
Size (mm)
Adopting Country
Russia (TSR), CIS, Baltic States,
Wide Gauge
1,520
Afghanistan, Finland, Mongolia
Europe (excluding Finland), China
Standard Gauge
1,435(TCR), North Korea, South Korea,
Japan (Shinkansen)
Japan (Railroad Line), Russia (Sakhalin,
Narrow Gauge
1,067
partially)
Source: Tsuji (2008)
Most of TSR section has already been completed to be double-tracked,
except the bridge of Amur River (2,658m) near Khabarovsk. Besides,
electrification was completed all along the TSR at the end of 2002.The
maximum haulage capacity per one train might be approximatelyIntermodal Mode Choice between Japan and Russia

95

July 2008, Thailand

200,000TEU/year. According to the report of Tsuji (2008), the most
attractive point of TSR is its short distance and leadtime. Comparing TSR
with SEA, total distance of TSR (about 10,000km) is only less than a half oftotal distance of SEA via Suez Canal (about 22.000km). Generally, TSR
uses high speed transport train called block train and its total leadtime fromJapan to Moscow can be reduced up to approximately 18 days including
SEA from Japan to Vostochny (TSR by block train only takes about 2
weeks) whereas total leadtime of SEA takes approximately 40 days. Blocktrain can be loaded 100-150 TEU and total length is about 1,000m. Average
speed is 45-55km/h (approximately 1,200km/day).
Table 2: Attributes of TSR from vostochny
Frequency Leadtime
Destination
NVOCC*
Shipper(times/week)(days)
Taganrog3
11
Russian Troika Hyundai Motors
Izhevsk
7-8
9FE Trans
Kia Motors
Moscow
1
11-12
Russian Troikan/aNote: *Non Vessel Operating Common Carriers
Source: Tsuji (2008)

3. ANALYSIS OF SEA&AIR
In order to revealing the potential of SEA&AIR which is considered basedon past practice, the interview survey on SEA&AIR and SEA&RAIL (TSR)
was 3 times carried out with major large-scale logistics company in Japanon 22nd November 2007, 20th December 2007 and 4th February 2008.
3.1 Reasons of declining SEA&AIR demand
From the interview surveys, it is revealed that SEA&AIR is no longer
expected as one of the alternative mode of SEA by five following reasons.
Economies of Scale (EOS): Cargoes transported by AIR are generally
packed by belly which is normally able to transport 15 ton at most, and are
fixed by pallet (sometimes called slid) which is a flat transport structure that
supports belly in a stable fashion while being lifted by a forklift, pallet jack,or other jacking device. Scale of pallet is fixed 100*100 in Asia; thereby
large quantity of cargo packed by belly cannot be transported by one
haulage. In this case, EOS does not work properly since it is not masstransportation like transported by container. According to interview surveys,
0.5 tons of lot size is impossible to work EOS even though it depends upon
commodity. In addition, appearance of jumbo jet plane can be considered as
declining SEA&AIR demand. Since jumbo jet is able to carryapproximately 100 tons per haulage, EOS can be worked by AIR only.
Risk on Transshipment Process: Second reason is risk ontransshipment process in the relay point, and which might be cause of loss
in leadtime due to transshipment time and even waiting time. The

96

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

convenience of facilities in relay point generally became better than before;
however, the weak point is transshipment process itself. It would
significantly be reduced shipper’s utility since there are several risks such as
delay (stuck), missing, theft and damage on goods. Solo-haulage such as
AIR and SEA cargo has no transshipment process like vanning anddevanning, besides, process such as making LCL (Less than Container
Load) cargo FCL (Full Container Load) after the custom clearance is much
shorter than SEA&AIR. Its process takes 4-5 days for SEA&AIR according
to the interview survey. Since SEA&AIR is generally included this process
at least one time, which is more complicated process than SEA due to that
container cannot consistently use, it is great disadvantage of SEA&AIR interms of not only leadtime but also other elements like delay, missing, theft
and damage on goods.
Size of Container: Different size of container between SEA and AIR
will be a cause of above two reasons such as EOS and risk on transshipment
process. Due to the size of container is different, the merit ofcontainerization cannot be utilized at most, and according to the interview
survey, it is practically impossible to unify the spec of cargo nowadays.
Low Fare of AIR: All of interviewees had answered that reason ofsuspending SEA&AIR service is due to low fare of AIR from the late 1900s.
In past (until early 1900s from the late 1980s), AIR fare was much more
expensive than current price, so freight forwarders reluctantly provide
SEA&AIR service as an alternative mode of AIR. One of the main reasonsof declining the demand on SEA&AIR service is that AIR fare was getting
lower and lower after the Gulf War. Before the reduction in AIR fare,operation of SEA&AIR was beneficial enough since the difference of pricebetween AIR and SEA&AIR is big enough to operate at that time; however,current price’s gap is not big enough to get benefit from SEA&AIR
operation. For instance, according to the freight forwarder who is currently
operating SEA&AIR, only 150JPY/kg is different between SEA andSEA&AIR (where relay point is Singapore) in the route between Japan andMiddle East whereas total leadtime is different 16 days in terms of port toport. Becoming large-scale jet of AIR can also be considered as a trend of
low fare of AIR freight, for example, Jumbo Jet can currently carrynormally 100 ton per haulage. So, demand on SEA&AIR is declining and
EOS possibly works by AIR rather than SEA&AIR. Only Jumbo Jet among
several types of jets sometimes transports 5 tons of semiconductor devices.
Growth of Supply Chain Management (SCM): According to themost of interviewees, haulage in the idea of SCM requires on-time
performance (punctuality) at most rather than other important factors suchas quick leadtime. Since there is risk of delay, missing and other incidents
violating punctuality in the relay point for transshipment (cancel of serviceof AIR or SEA) which is causing producing operations in manufacture, line
parts tended to avoid to be carried by SEA&AIR. As SCM developed,
technology improvement on SEA is remarkable developed as well. SEA
transport mode such as container ship, RORO ship and Felly are currently
enabling rapid transit and it is punctual enough. By its technology

Intermodal Mode Choice between Japan and Russia

97

July 2008, Thailand

improvement on maritime transport, it is possible to structure SCM by SEA
transportation. In this situation, according to the interviewee, there is somepossibility to decline demand on AIR haulage in Asia.

3.2 Conclusion of SEA&AIR
As we have seen the analysis on SEA&AIR based upon interview
survey until previous section, demand of SEA&AIR will not be expected to
grow more. Hence, SEA&AIR is not suitable for one of the alternative
freight modes on Japan-Russia (Moscow) route as well as competitor of
SEA and TSR. However, in the future, it may be expected few demand on
SEA&AIR in the case of that AIR fare rapidly rise due to a jump in crude
oil prices that significantly effects on fuel surcharge. In these years, cargoes
originated at Japan tended to be transported without AIR due to thebackground of rise in fuel surcharge and rise in fare due to high competition
with Asian countries. So airlift tends to be used for goods when are reallyneeded to be transported by AIR.

4. FREIGHT MODE CHOICE MODELINGThe primary objective of this study is to estimate an impact on mode choiceby emerging alternative mode (TSR) of SEA focusing on the route between
Japan and Russia in order to reveal shippers’ preferences and importantfactor affecting mode choice. To perform our analysis, we have chosenStated Preference (SP) method rather than Revealed Preference (RP)method which is underlying actual observed behavior. It is not feasible toobtain the respondents’ RP on the mode choice in this study since there isalmost no practice of SEA&AIR and TSR. Thus, this study applies SP
method that is based on several hypothetical scenarios but practical values
enough. After that, questionnaire will be formatted by the Design ofExperiment (DOE). Obtained data are calibrated by NLOGIT software
which is used for estimating Binary Logit (BL) model as described equation
(1).

Piq =
where
Piq
=
β
=
V
=

exp( β Viq )(1)

1 + exp( β iq )Probability of that individual q chooses i
Parameter
Measureable utility

4.1 Levels of each attributes

As a result of interview survey with freight forwarders, the different
independent variables are analyzed in associate with statistical and the
goodness-of-fit test. The variables used in this computation are categorized
into five elements such as leadtime, cost, punctuality, frequency and security

98

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

which levels are set based on interview survey. All of independent variables
are used to calculate the utility function and develop the freight mode choicemodels. Since inclusion of many variables might cause complexity andunreasonable result to the models, dependent variables are winnowed. The
statistical tests are applied to examine utility function and to calibrate themodel. The preferable model is better to have magnitude and sign ofstatistical test values in harmony with reasonable expectation.
Table 3: Levels of each attributes
Level
Attributes
SEA
SEA&RAIL (TSR)
15days, 25days
Leadtime
40days$7,500, $8,500
Cost*$7,000
Punctuality
Punctual, Unpunctual
Punctual, Unpunctual
1time/day, 1time/week
Frequency
1time/day, 1time/week
High, Low
Security
High, Low
Note: *one-way haulage (Japan-Moscow) by 40’ container
These degrees of level on leadtime and cost are determined as a resultof interview survey with three freight forwarders but it is based upon deep
examination by using several journal articles, papers and discussion withfreight forwarders, hence; these values should be practical enough even if
they were in actual international logistics market.
4.2 Model calibration and test

Target numbers of respondents are five shippers, and they all arecompanies related to automobile and electrical manufacture. Validate
sample number is 76 sample sets out of 80 sets. The calibration process isbased upon Maximum Likelihood (ML) method. In addition, this study
assumes that there is no significant difference in other words, statisticallyindependent among different variables.
4.3 Results of model calibration

The calibration results of BL model are presented in Table 4 showing
the estimated coefficients of the variables and the statistic results. Althought-value of both punctuality and frequency is not high, -1.023 and -0.599,
respectively, of other variable are relatively high; thus, they can be said
statistically significant. Considering a fact that ρ2 is relatively low, thisestimated model will be used as a rough reference for the demand
forecasting.

Intermodal Mode Choice between Japan and Russia

99

July 2008, Thailand

Table 4: Calibration result of binary freight mode choice
Explanatory
EstimatedStandard
t-value
Variables
Coefficients
Error
Model Constants
1.271
1.120105
1.423382
SEA
0TSR (base)
Leadtime (day)-0.048939
0.047842-1.023
Cost (US $)-0.7608e-04
0.000127-0.599Punctuality
0.679197
0.352819
1.925
Frequency
0.553472
0.353790
1.564
Security
1.352651
0.354754
3.813
Estimated Statistics ValuesL(β)-93.2585
L(0)-105.3584
Likelihood Ratio Test 24.1998
Rho-bar-squared
0.11485
From the result of calibration process, utility function of each freightmode can be listed as follows;
USEA = - 0.048939(leadtime) - 0.7608e-04(cost) + 0.679197(punctuality)+ 0.553472(frequency) + 1.352651(security) + 1.423382
UTSR = - 0.048939(leadtime) - 0.7608e-04(cost) + 0.679197(punctuality)+ 0.553472(frequency) + 1.352651(security)

5. CONCLUSION AND DISCUSSIONAs any company hugely weight on the attributes of security, estimatedmodel also concludes that the security is weighted at the top priority. Unitchange on security has the approximately the twice impact of unit change on
punctuality that has more impact rather than frequency. One of the reasons
why shippers put a priority on security is that due to a fact that TSR is
unknown very much among logistics companies even the information of
TSR fare is very difficult to know, which is normally determined by anegotiation (Tsuji, 2008). In case most part of haulage process is unrevealed,shippers may be sensitive to security including theft and damage. In
addition, since the damaged commodity no longer is used for line parts, itwill link to the tremendous loss in terms of time and cost.
Regarding to the attributes of frequency, as no company was sensitive
to it, estimated model also show that frequency has the lowest influence on
the overall utility, which is less than half impact of security and less thanpunctuality as well. This result can be considered as that frequency of atleast 1time/week may be acceptable enough for shippers. Company C statedthat forwarding commodity is not daily, if frequency is at least
1shipment/week, it cannot be a reason of not use. Hence, although higher
frequency is preferable, it can be said that TSR can supply enough100

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

frequency to shippers since there is weekly shipment via Pusan, Korea
Estimated model revealed that punctuality is slightly higher impact
than frequency but only half effect of security on the overall utility. This
result is somewhat lower than we expected since punctuality is revealed
quite important attributes as a growth of SCM according to the interview
survey. This may be due to the assumption of punctuality is not suitablesince it is expressed by “unpunctual” and “punctual”.
This study assumes that each attributes are statistically independent
from other attributes. However, in the real world, several affections fromother attributes are existed no matter it is small or big. In this study, it can beconsidered that the attributes of security and punctuality might have an
impact each other. For example, in case of the low security, respondents
might assume that the probability of happening delay may be high.
Considering its fact, each attributes cannot always be said statisticallyindependent one another.
Leadtime and cost are also somewhat low; however, this should bereasonable results since most of companies made a decision by comparing
leadtime and cost not as a solo attributes, so shippers may consider these
two attributes as one attributes. For example, short leadtime and high cost
may be roughly same utility as long leadtime and low cost.
As for the parameter of cost, it is estimated relatively low, which does
not affect a significant impact on the mode choice. For example, as percent
decrease in cost of TSR by 10 %, percent choice of mode increases only 2%.
This might be due to the setting of value of cost. For example, the gap of
cost between the values of TSR is $1,000 maximum. If values were set asbigger and smaller like $9,000 and $6,500 that is cheaper than SEA
although it is excessive value as well as not practical, parameter of cost will
be higher than estimated here.
Sign of each coefficient of each variable are estimated as expected, forexample, the parameters of leadtime and cost are with negative sign since
the utility is decreased as leadtime and cost get increase. On the other hand,the signs of other variables are estimated with positive sign. The
contribution to the overall satisfaction by alternatives is given by thesecoefficients. The positive sign of constant value in the utility function of
SEA can be interrupted as representing the net influence of all unobserved(not explicitly included) characteristics of the option. For example, shippers’
image (reliability) towards mode choice could be included; however, it
should be quite difficult to observe in this study. Moreover, SEA-basedmodel which includes constant value in TSR with negative sign is also
estimated as shown in Table 5.5. From its model, it can be speculated that
there might be several resistance factors towards TSR other than estimatedfactors.
Russian Railway should open the information and plan of fare in order
to secure the users of TSR. Moreover, since security is the most importantIntermodal Mode Choice between Japan and Russia

101

July 2008, Thailand

attributes among the estimated attributes for shippers, security should be
improved especially damage on commodity.

REFERENCES

Ben-Akiva M. and Lerman S. R., 1985. Discrete Choice Analysis: Theory
and Application to Travel Demand. The MIT Press.
Bernd H., 2005. ‘Airport Logistics: Innovative Solutions for Baggagehandling’. Log-forum Vol. 1, Issue 2, No. 5.
Devore J. L., 2000. Probability and Statistics for Engineering and Sciences.
5th edition, Duxbury Thomson Learning.
Federal Transportation Administration (FTA)., 2000. A Self Instructing
Course in Disaggregate Mode Choice Modeling, US. FTA.
Institution for Transport Policy Studies, 2002. The Report on Flight Service
for International Air Cargo. Institution for Transport Policy Studies.
Kou R., 2007. Analysis on sea port for international competitiveness inJapan. Journal of Management in Ritsumeikan University, Vol. 41, No.
1, pp167-188.
Louviere J. J. et al., 2000. Stated Choice Methods: Analysis and Application.
Cambridge University Press.
Ocean Commerce Ltd., 2006. International Transportation Handbook 2007.
Ocean Commerce Ltd.
Ohmura H., 2002. Lecture on Design of Experiment (DOE) and Analysis of
Variance. JUSE Press
Ortuzar J. de D. and Willumsen L. G., 2001. Modeling Transport. 3rd edition,
John Wiley & sons.
The Workshop on Transportation Engineering., 1995. Disaggregate Travel
Demand Analysis made simple. SANBI Printing.
Tsuji H., 2007. The Trans-Siberian Railway Land Bridge: The Main Arteryof Japanese-Russian Business. The Seizando Press.

102

Joint Student Seminar on Civil Infrastructures

NON-LINEAR BEHAVIOR OF
NEW TYPE GIRDER FILLED BY
HIGH-STRENGTH CONCRETE
SUNG WOO, CHOI
Department of Architectural, Civil and Environment Engineering
Korea University, Seoul, Korea
1905vocal@hanmail.net
ABSTRACT
Recently, many studies about high-strength concrete and composite
structures are being progressed to get the more economic and stable resultin the construction of structure all over the world. One of those studies isabout CFTA(Concrete Filled and Tied Steel Tubular Arch) girder thatapplies an arch structure and a pre-stressed structure to CFT(Concrete
Filled Steel Tubular) Structure which is filled with a concrete and improve
the stiffness and strength of the structure by the confinement effect of fillers
to maximize the efficiency of structure and economic. In this study, nonlinear behavior of CFTA girders filled with a general concrete and the highstrength concrete respectively were analyzed by using ABAQUS 6.5-1 andresults were compared.

1. INTRODUCTION
1.1 Introduction
Recently, many studies about shape of bridge’s superstructure,efficiency of materials and complex structure are being progressed forbridges, more safety, economical and well harmonized into nature, in theconstruction for structure all over the world. SCP Girder, as an example,
which has similar cross section shape of PSC girder is filled with a prestressed concrete. In this manner, studies about new types of bridge
superstructure which can minimize shortcomings of the existingsuperstructure of bridge by performance improvement from rearranging ofstructure shapes and materials, using tensile force, and being beneficial for
economic as well as aesthetic part are being progressed.
1.2 Research objective
As mentioned above, studies about new types of synthetic structureand girder system of bridges are being progressed these days. However, as itis hard to be used on actual construction field immediately, it is needed todevelop new structure types which can be applied without further delay andminimize some weak points of existing structure stuffs. ‘Concrete Filledsteel tubular Tied Arch composite (CFTA) girder’, one of the new types of103

July 2008, Thailand

complex structure girder, is studied for this purpose. In this study non-linear
behavior of CFTA girders filled with normal-strength (30Mpa) concrete andhigh-strength (150Mpa, 200Mpa) concrete respectively were analyzed andresults were compared.

2. CFTA girder (Concrete-Filled and Tied Steel Tubular Arch Girder)and modeling
The top side of CFTA girder filled with concrete in steel tube maintains
constant height, while the bottom side of CFTA girder is the arch shape.
Besides, prestress is put on steel tendons exposed at the lower part of CFTA
girder to improve its safety and to reduce its weight.
The solid drawing and the constituent material of CFTA girder are
showed Figure 1 and 2. As like Figure 1, the height of CFTA girder at bothends is 620mm and filled with concrete. As going to the center part, theshape of the inner filled concrete is the arch shape with maintaining 180mm
thickness. Tendons are inserted until 520mm from both ends, and then they
are exposed to outside because of the arch shape of CFTA girder. The steel
box on the concrete arch is the empty and transmits the load from upper partof steel box to the concrete arch. The length of the whole span is 12.2m, thewidth is 500mm and the displacement control load is applied to perform thenon-linear analysis. Besides, material properties and the load condition are
as following table 1.

Figure 1: The solid drawing of CFTA girder

Figure 2: The constituent material of CFTA girder

104

Joint Student Seminar on Civil Infrastructure

ICUS Report 30

Table 1: Material Properties and the Load Condition of Members.
CocreteSteel Plate
30Mpa
150Mpa200MpaModulus of
26844
43168
47304
200000elasticity (Mpa)
Poisson's ratio
0.16
0.16
0.16
0.3
Unit mass(kg/m3)
2500
2500
2500
7700
Acceleration of
9.81
gravity(m/s2)
Pre-tension(MPa)744.48

3. The Result of analysis
Even though the high strength concrete has 5 and 6.7 times compression
strength as compared with the normal strength concrete respectively, theaspect of the load-displacement curve doesn’t have a big difference.
Contrary to the expectation that high strength concrete can support 5 and 6.7
times load as compared with normal strength concrete respectively, it meansthat the non-linear behavior of the high strength concrete is different with
the normal strength concrete’s. To know differences between the non-linear
behavior of the high strength concrete and the non-linear behavior of thenormal strength concrete, load-strain curve is drawn for central parts of eachstrength concrete in Figure 3.1 ~ 3.4.

Figure 3.1: Load-strain curve of the top of the slab

Figure 3.2: Load-strain curve of the bottom of the slab

Non-Linear Behavior of New Type Girder Filled by High Strength Concrete

105

July 2008, Thailand

Figure 3.3: Load-strain curve of the top of the conctrte

Figure 3.4: Load-strain curve of the bottom of the concrete
As shown in Figure 3.1 ~ 3.4 above, between the high strength
concrete and the normal strength concrete, load–strain curves for the top of
the slab and the bottom of the filled concrete have just different size but
have the same aspect. On the other hand, behavior for the bottom of the slab
and the top of the filled concrete is totally different between the highstrength concrete and the normal strength concrete. In other words, in caseof 30MPa concrete, the bottom of the slab and the top of the filled concrete
are continuously under compression from the beginning of loading to theend of the analysis. However, in case of high strength concrete, its condition
is turned under compression into under tension from about 200KN. It meansthat as increasing load, the neutral-axis is going up, therefore the bottom of
the slab and the top of the filled concrete are under the neutral-axis andunder tension.
In case of non-linear behavior like that, to know the change of theneutral-axis of CFTA girder, it is drawn the change of the neutral-axis at thecentral section of each concrete for each strength in Figure 4. The reason
why the discontinuous part of the graph is appeared is guessed that the pointchanged the up convexity shape into the down convexity shape is notincluded in the shown points by analysis program. Therefore, the effective
neutral-axis area is started when the load become 25KN because the neutralaxis is appeared in the filled concrete from that time. In case of the normal
strength concrete, the neutral-axis is located in the filled concrete at the endof analysis. On the contrary, in case of high strength concrete, the location

106

Joint Student Seminar on Civil Infrastructure

ICUS Report 30of the neutral-axis is going up to the slab at the end of analysis. It means thattensional destruction of the filled concrete can be occurred and it is very
uneconomic design. Besides, contrary to the definitely different behavior
between the high strength concrete and the normal strength concrete, thehigh strength concrete, 150MPa strength concrete and 200MPa strength
concrete, show the similar behavior. As one cause of this phenomenon, both
concrete are the high strength concrete so it is possible to be thought that
there are some similarities of behavior between them. Also, another cause
might be that other conditions such as the strength of steel, the strength oftendon, load condition and so on, except the strength of concrete, are same.
Therefore, to get more accurate result, all other conditions have to be fitted
to the concrete strength.
As knowing from the result of analysis, there are many differences
between the non-linear behavior of the high strength concrete and the nonlinear behavior of the normal strength concrete. So if a engineer designs ahigh strength concrete structure using the specification for the normal
strength concrete, it will be very uneconomic, inefficient and also have a
low reliability. Consequently, to make the best use of the high strength
concrete, it is very important and imperative to make a new specification forthe design of the high strength concrete.

REFERENCES
Hak, Lee., Ho, Park., EunHo, Lee., JungHo, Kim., JungSik, Kong., 2007.
Behavior of Concrete-Filled and Tied Steel Tubular Arch Girder.
Spring Conference Paper Book 668-693. Computational StructuralEngineering Institute of Korea.
Ho, Park., MyungKyun, Park., KyungHun, Park., JungHo, Kim., 2006.
Development of Concrete-Filled and Tied Steel Tubular Arch Girder.
Conference Paper Book 2289-2292. Korean Society of Civil
Engineers.
SungWon, Yoo., KyungWook, Hong., 2000. Bending Analysis andImprovement of Bending Capacity of Pre-stress Concrete Beam Using
the Partly Attached Rigid Model. The collection of learned papers
813-821. Korean Society of Civil Engineers.
ByungHwan, Oh., SungWon, Yoo., 2000. Bending Behavior Test of PSC
Beam Which has the External Steel Wire according to the Shape of
Steel Wire and the Number of deflection side. The collection oflearned papers 795-804. Korean Society of Civil Engineers.

Non-Linear Behavior of New Type Girder Filled by High Strength Concrete107

July 2008, Thailand

108

Joint Student Seminar on Civil InfrastructureELASTODYNAMIC ANALYSIS BY BEM
USING DOMAIN DECOMPOSITIONMETHOD AND PARTICULAR INTEGRALSADISORN OWATSIRIWONG, BUPAVECH PHANSRI
and KYUNG-HO PARK
School of Engineering and Technology
Asian Institute of Technology, Thailand
adisorn.owatsiriwong@ait.ac.th

ABSTRACTThe paper presents the elastodynamic BEM analysis using the domain
decomposition method (DDM) and particular integrals. The domain of theoriginal problem is subdivided into two sub-regions in which each can betreated as sub-problem and independently solved. Particular integral
method in association with Houbolt time integration is utilized to formulate
the system equation. The iterative coupling approach via alternating
Schwarz algorithm is applied to solve each sub-region in turn. To assist
convergence rate of the iteration process, an under-relaxation parameter isintroduced to the displacement variable. Two numerical example problems
are given to demonstrate the accuracy and validity of the present
formulation. Comparison of the results is made with those from ABAQUS.

1. INTRODUCTION
Boundary element method (BEM) has long been accepted as an efficientand accurate numerical technique for solving elastodynamic problems. Withaid of the domain decomposition method (DDM), nowadays, applications ofelastodynamic BEM not only restrict to single-region problems but also
extend to the problems involving piecewise inhomogeneities and multi-part
assembly.
Early developments of multi-region techniques employing DDM in
solid mechanics had focused mainly on the direct coupling approach for the
problem involving zone inhomogeneities (Banerjee and Butterfield, 1981;
Banerjee 1994; Kane et al., 1990). In such approaches, sub-regions areassembled into a single equation system and solved either by direct or
iterative methods. A variant of DDM that does not require direct assemblyof the system equations is so-called iterative coupling approach (Smith et al.,1996). Aiming to avoid solving large global equation system and difficult
programming issues, many iterative coupling approaches have been
introduced mostly in the context of FEM-BEM and BEM-BEM couplingtechniques. The early formulations employing iterative coupling method tocoupling FE and BE domains can be found in the works of Lin et al. (1996)
and Feng and Owen (1996), who presented the Dirichlet-Neumann form of109

July 2008, Thailand

alternating Schwarz algorithm to solve 2D elastostatics. Kamiya et al.
(1996) implemented the Neumann-Neumann and Dirichlet-Neumann for
FE-BE coupling in parallelization scheme and tested them with 2D potential
problems. Elleithy et al. (2001) used a simple 2D elastostatic problem toinvestigate the effect of various parameters such as relaxation constant,mesh density, and relative area of BE-FE domains. Eleithy and Al-Gahtani(2000) presented various schemes of overlapping DDM based on alternating
Schwarz framework to solve simple 2D elastostatic problems by FE-BE
coupling. They also mentioned the failure of Dirichlet-Neumann algorithm
when Neumann boundary condition is applied to the entire problem domain.
In fact, this statement is correct as well when using Dirichlet-Neumannalgorithm to analyze multi-region problems in BEM. Recently von Estorffand Hagen (2006) applied double relaxation algorithm to the 2D and 3D
elastodynamic problems for FE-BE coupling technique. In most cases,
stability and convergence properties of most iterative coupling methods rely
on how good the value of relaxation parameter is guessed, but this is not acase for the overlapping DDM.
This paper deals with the elastodynamic BEM analysis using the
DDM and particular integrals. The paper is organized as follows: In the next
section, the particular integral formulation for approximating acceleration
term is presented. In section 3, we describe the DDM based on alternating
Schwarz algorithm and how it can be applied to the elastodynamic BEM.
Numerical algorithm based on block Gauss-Seidel and block Jacobi forms
will also be described. Finally, two numerical example problems are given
to demonstrate the validity and accuracy of the present formulation.

2. PARTICULAR INTEGRAL FORMULATION
The governing differential equation for transient elastodynamic analysis of ahomogeneous, isotropic body in the absence of body force can be expressedas( λ + μ ) u j , ji + μ ui , jj = ρ u&&i

(1)&&i is the acceleration, ρ is the mass
where ui is the displacement, udensity, λ and μ are Lame’s constants, commas represent differentiation
with respect to spatial coordinates, and i, j = 1,2(3) for two(three)dimensions. The solution of equation 1 can be represented as a sum ofccomplementary function ui satisfying the homogeneous equation(λ + μ ) u cj , ji + μ uic, jj = 0(2)

and particular integral uip satisfying the inhomogeneous equation( λ + μ ) u jp, ji + μ uip, jj = ρ u&&i
110

(3)

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

where superscripts c and p indicate complementary and particularsolutions respectively. Then the total solutions for displacement, traction
and stress rates can be expressed as
u i = u ic + u ip ;t i = t ic + t ip(4)

where tic and tip are the complementary functions and particular
integrals for traction, respectively.

2.1. Complementary solutions
The boundary integral equation related to the complementaryccfunctions, ui and ti , can be written as (Banerjee, 1994)
Cij ( ξ ) uic ( ξ ) = ∫ ⎡⎣Gij ( x, ξ ) tic ( x ) − Fij ( x, ξ ) uic ( x ) ⎤⎦ dS ( x )S(5)where Gij , Fij are the fundamental solutions for elastostatic equation and
Cij ( ξ ) = 1, 0 and 1/2 depending on the point ξ being in the interior, outside

or on a smooth boundary point respectively.

2.2. Particular integrals
In order to eliminate the domain integrals due to the acceleration term,
the concept of global shape function can be used. By introducing the global
shape function Cik (x, ξ n ) , the acceleration u&&i (x ) can be approximated as∞u&&i (x ) = ∑ C ik (x, ξ n ) φ&&k (ξ n )

(6)

n =1

where φ&&k (ξ n ) is the fictitious function. Then the particular integrals
for displacement, stress and traction rates can be obtained as∞

u ip (x ) = ∑ U ik (x, ξ n ) φ&&k (ξ n )(7)

t ip (x ) = ∑ Tik (x, ξ n ) φ&&k (ξ n )

(8)

n =1
∞

n =1

3. NUMERICAL IMPLEMENTATIONThe boundary integral equation (5) can be written in matrix form as

Elastodynamic Analysis by BEM Using DDM and Particular Integrals

111

July 2008, Thailand[G] { t c }− [F ] { u c }= 0(9)Considering the total solutions of equation 4 the complementaryfunctions in equation 9 can be eliminated as[G] { t} − [ F ] { u} = [G] { t p } − [ F ] { u p }(10)

If a finite number of ξ n are chosen, the particular integrals fordisplacement and traction can be written as{u } = [U ] {φ&&} ; {t } = [ T ] {φ&&}
p

p

(11)

Considering the fictitious nodal values as{φ&&} = [C ] {u&&}
−1

(12)

one can obtain the following equations[ G ] { t} − [ F ] { u} = [ M ] { u&&}

(13)

where

[ M ] = ( [ G ] ⎡⎣ T ⎤⎦ − [ F ] ⎡⎣ U ⎤⎦ ) [ C ] −1

(14)

Several time integration schemes have been proposed to deal withequations of the type of equation 13 in FEM. In this study, the Houbolt
method is used such thatu&&t +Δt =1( 2ut +Δt − 5ut + 4ut −Δt − ut −2 Δt )
Δt 2

(15)

Considering the equilibrium equation (13) at time t+ Δ t one canobtain1⎛ 2⎞⎜ 2 [ M ] + [ F ] ⎟ { u}t +Δt = [ G ] {t}t +Δt + 2 [ M ] ( 5{u}t )
Δt
⎝ Δt
⎠
−4 {u}t −Δt + {u}t −2 Δt(16)

To solve the system equation (16), boundary variables as well as
displacement at interior points are simultaneously treated as the unknown
variables. So equation 14 is rewritten as⎛ ⎡[ G ] ⎤⎡[ F ] bb [0]⎤ ⎡[ U ] b ⎤ ⎞−1⎥ ⎢⎥ ⎟ [ C ] b+ I
[ M ] b+ I = ⎜ ⎢ bb ⎥ [ T ] b − ⎢⎜ ⎣⎢[ G ] Ib ⎦⎥⎢⎣[ F ] Ib [ I ]⎥⎦ ⎢⎣[ U ] I ⎥⎦ ⎟⎠⎝(17)

where [ I ] is identity matrix, subscript I denotes interior values andsubscript b indicates boundary values. By substituting the boundary

112

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

conditions at time t + Δ t and taking all the unknowns to the left-hand side,
the final system of equation can be rewritten as[ A] {x}t +Δt = { y}t +Δt(18)

where x is unknown vector of displacement and traction including
displacement at interior points, y is a known vector and A is thecoefficient matrix.

4. DOMAIN DECOMPOSITION METHOD
4.1 Introduction

Applying the DDM, the problem domain is subdivided into two
regions in which the system equation (18) holds for each (Figure 1). At theinterface, the equilibrium and compatibility conditions must be satisfied
such that{u } = {u }{t } + {t } = 0
IF t +1II
F t +1on Γ F(19a)

I
F t +1II
F t +1on Γ F(19b)

It is commonly possible to solve the entire problem either by direct or
iterative coupling approach. In the direct coupling approach (Banerjee,1994), two sub-regions are brought to assemble by utilizing interface
boundary conditions in equation 19. The solution can be obtained within asingle step if direct solver is also used. On the contrary, the iterative
coupling approach allows solving each sub-region independently. Interface
boundary conditions will be prescribed iteratively until convergence isreached. Commonly, computational efficiency of the direct method is great,but in some stringent cases either the system matrix could become ill or the
results could be numerically unstable. Despite less efficient when
implemented on a sequential code, iterative coupling approach offers
flexibility and generality to the DDM framework. Since the structure of subsystem matrix is completely retained, implementation of the method is by
far simpler than that of direct coupling approach. In this paper, weconcentrate only on the indirect coupling approach. The calculation
sequence will be described in the next section.

4.2 Iterative coupling DDM

Indirect coupling approach can be performed by so-called alternating
Schwarz algorithm. To explain the algorithm, it is useful to rewrite thesystem equation (18) in partitioned form where traction and displacement
unknowns are separated. Consider the system equation

Elastodynamic Analysis by BEM Using DDM and Particular Integrals

113

July 2008, Thailand

Figure 1: A domain decomposed into two sub-regions⎡[ A]11⎢⎣[ A]21⎧⎪{ y}1 ⎫⎪[ A]12 ⎤ ⎧{u}⎫⎥ ⎨ ⎬ =⎨[ A]22 ⎦ ⎩ {t} ⎭t +Δt ⎪⎩{ y}2 ⎬⎭⎪t +Δt(20)

where for each region, let {u I , II } = {{u I , II }, {uFI , II }} and {t I ,II } = {{t I , II },{tFI ,II }} .
T

T

Subscript F denotes the variable that belongs to interface boundary. A
sequential form of Dirichlet-Neumann algorithm can be described asfollows:
For t =0, Δt , 2 Δt ,… do

Assume initial value of {uFI }

0

t +1

=0

For n =1, 2,… do(1) Solve sub-problem I from⎡[ A]I⎢ 11
I⎢⎣[ A]21⎧⎫[ A]12I ⎤ ⎪⎧{u }⎪⎫⎪{ y }1 ⎪
⎥
⎨
⎬ =⎨
⎬
[ A]22I ⎥⎦ ⎪⎩ {t I } ⎪⎭t +Δt ⎪⎩{ y I }2 ⎪⎭t +ΔtI{ }(2) Apply tFIInn

= − {tFI }

n

t +Δt

t +Δt

I

n

(21)

on Γ F(3) Solve sub-problem II from⎡[ A]II⎢ 11
II⎢⎣[ A]21(4) Apply {uFI }

n +1

t +1

II
⎧ II , I F ⎫[ A]12II ⎤ ⎧⎪{u }⎫⎪⎪{ y }1 ⎪
⎥ ⎨
⎬ =⎨
⎬
[ A]22II ⎥⎦ ⎪⎩ {t II } ⎪⎭t +Δt ⎪⎩ { y II }2 ⎪⎭t +Δt
n

n

(22)

= (1 − ω ) {uFI } + ω {uFII }
n

n

t +1

t +1

where ω is an under relaxation parameter to assist convergence. The
value is problem dependent. For initial guess, value of ω =0.5 may be used.
(5) Check convergence of the solution from

114

Joint Student Seminar on Civil Infrastructures

ICUS Report 30{u }I n +1
F t +Δt− {uFI }

n

t +Δt

{u }

n +1

< ε

( given tolerance)(23)

I
F t +Δt(6) Finish current time step if the solution converges, otherwise repeat
step (1).

To implement Dirichlet-Neumann algorithm, it is demanded that each
subproblem be well-posed. Basically, start-up region can be arbitrary chosen.
The present algorithm is considered as a block Gauss-Seidel form. Block
Jacobi form of solution can be simply obtained by updating all interface
boundary variables together after completion of the iteration step (Smith etal., 1996).

5. NUMERICAL EXAMPLES
5.1 Example 1: A cavity subjected to internal pressure

The first example deals with a cavity subjected to suddenly appliedinternal pressure. The inner and outer radii of the truncated cavity are taken
to be 1 and 10 respectively. The full model under plane strain condition isdivided into two sub-regions modeled by 32 quadratic boundary elements
and 160 interior points each (Figure 2). Internal pressure is suddenly appliedand held constant. The material is linearly elastic with the following
properties: E = 94.67, ν = 0.23 and ρ = 1. For the given properties, thetheoretical compressional wave speed is computed as c1 = 10.47. The time
step Δt is taken to be 0.01.
The radial displacement at point A (2, 0) is plotted against time asshown in Figure 3. It can be shown that the value of compressional wave
speed obtained from the analysis model ( c1 = s / tq = 1.0 / 0.095 = 10.52 )deviates only 0.47% from the theoretical value, where s and tq denote thetravelling wave distance and tranquil period of particle motion, respectively.
Slight fluctuation of ABAQUS result around that of BEM can be noticed.
Generally, acceptably good agreement is observed.

Elastodynamic Analysis by BEM Using DDM and Particular Integrals

115

July 2008, Thailand

p(t)

1

t

Ω1
ΓF
Ω2

p(t )

A(2,0)
Ω1

Figure 2: Modeling mesh (Example 1)

Figure 3: Plot of displacement at point A (2,0) (Example 1)
5.2 Example 2: Seismic analysis of a concrete gravity dam

This example presents seismic analysis of a concrete gravity dam(Owen and Hinton, 1980) with considering foundation-dam interaction. The
model under plane strain condition is divided into two sub-regions withdifferent material properties - concrete and rock. Material properties used
are E = 3.164x106, ν = 0.2 and ρ = 0.269 for concrete dam, and E =1.8x106, ν = 0.2 and ρ = 0.183 for rock foundation. The dam ( Ω1 ) ismodeled by 24 quadratic boundary elements and 73 interior points, while
the foundation ( Ω 2 ) is modeled by 26 quadratic boundary elements and 65
interior points (Figure 4). Theoretical sinesweep ground acceleration isprescribed in the horizontal direction. Time history analysis is performed
using Δt = 0.01.

116

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

The displacement at dam crest relative to dam base is depicted in
Figure 5. Good agreement to ABAQUS’s result can be noticed particularly
before t = 2.5 . The non-vanishing result at first time step arises from theprescribed initial conditions i.e. body force and hydrostatic pressure in static
steps. The effect of hydrodynamic pressure is omitted from this present
example.

Ω1
Sinesweep ground acceleration

ΓF
Ω2

Figure 4: Modeling mesh (Example 2)

Figure 5: Horizontal crest displacement relative to dam base (Example 2)

6. CONCLUSIONSA BEM formulation for elastodynamic analysis using DDM andparticular integrals has been presented. Based on iterative coupling DDM
approach, the analysis domain was subdivided into two regions. Alternating

Elastodynamic Analysis by BEM Using DDM and Particular Integrals

117

July 2008, Thailand

Schwarz algorithm can then be applied to obtain the solution for each subregion iteratively until convergence is satisfied. The accuracy and validity ofthe present formulation is evaluated by comparing the results of two
example problems with ABAQUS.

REFERENCES

P.K. Banerjee, R. Butterfield, 1981. Boundary Element Methods inEngineering Science, McGraw-Hill: London.
P.K. Banerjee, 1994. The Boundary Element Methods in Engineering,
McGraw-Hill: London.
W.M. Elleithy, H.J. Al-Gahtani, 2000. An overlapping domain
decomposition approach for coupling the finite and boundary element
methods. Eng. Anal. Boun. Elements. 24, 391-398.
W. M. Elleithy, H.J. Al-Gahtani, M. El-Gebeily, 2001. Iterative coupling of
BE and FE methods in elastostatics. Eng. Anal. Boun. Elements. 25,
685-695.
Y.T. Feng, D.R.J. Owen, 1996. Iterative solution of coupled FE/BE
discretizations for plate-foundation interaction problems. Int. J. Numer.
Meth. Eng. 39, 1889-1901.
X-W. Gao, T.G. Davies, 2000. 3D Multi-region BEM with corners andedges. Int. J. Solids Struct. 37, 1549-1560.
N. Kamiya, I. Hidehito, K. Eisuka, 1996. Parallel computing for the
combination method of BEM and FEM. Eng. Anal. Boundary
Elements. 18, 221-229.
J.H. Kane, B.L.K. Kumar, S. Saigal, 1990. An arbitrary multi-zone
condensation technique for boundary element design sensitivity
analysis. AIAA J. 28, 1277-1284.
C.-C. Lin, E.C. Lawton, J.A. Caliendo, L.R. Anderson, 1996. An iterative
finite element-boundary element algorithm. Comput. Struct. 39 (5),899-909.
B. Smith, P. Bjorstad, W. Gropp , 1996. Domain Decomposition: Parallel
Multilevel Methods for Elliptic Partial Differential Equations,Cambridge University Press.
O. von Estorff, C. Hagen, 2006. Iterative coupling of FEM and BEM in 3D
transient elastodynamics. Eng. Anal. Boun. Elements. 30, 611-622.
D.R.J. Owen, E. Hinton, 1980. Finite Elements in Plasticity: Theory andPractice, Pineridge Press: Swansea.

118

Joint Student Seminar on Civil Infrastructures

EVALUATION OF WILDFIRE DURATIONTIME OVER ASIA USINGMTSAT AND MODISYUSUKE MATSUMURA1, WATARU TAKEUCHI2,HARUO SAWADA3 and YOSHIFUMI YASUOKA4
1-3
Institute of Industrial Science, The University of Tokyo, Japan
4
National Institute of Environment Studies, Japan
yusukem@iis.u-tokyo.ac.jp
ABSTRACTIn this study, we present an approach to evaluate a wildfire duration
time. An-hourly MTSAT imagery is quite powerful to obtain the duration
time of rapid fire events such as a grass land fire that cannot be detectedwith the frequency of MODIS. Research areas are evergreen needleleaf
forest in far- east Russia and evergreen broadleaf forest in Sumatra. Our
approach is based on a model that the temperature of the pixel becomes
higher than the non-fire pixels if there is some wildfire in the pixel. As aresult, it is found that fire duration time is detected by comparing the fire
pixel which contains hotspots with a non-fire pixel around it. This technique
is useful to detect wildfire duration time even land coverage is evergreen
needleleaf forests or evergreen broadleaf forests. We can conclude that anhourly based monitoring provides us with a sufficient time resolution andplays an important role to monitor wild fire duration time despite a lower
spatial resolution in 4 kilometer than that of MODIS in 1 kilometer.

1. INTRODUCTION
1.1 Background
Serious wildfire occurs in Asia so frequently. It causes not only
threads for inhabitants but also global warming or smog problem forneighbor countries (UNDP, 2001). Most of wild fires occur in hardly
accessible places. Therefore, remote sensing is one of very useful tools tofind or evaluate the wild fire.
There are many researches to get better information of wildfires. For
example, methods of finding wildfire hotspots using high time resolution
data such as MODIS are suggested(Kaufman et al., 1997) and detection ofburning area using high spatial resolution data such as Landsat TM, SPOT
HRV, Terra ASTER(Takeuchi et al., 2005). At the current situation,
however, despite the advent of satellite imagery and the growing
significance of fires to understand a condition of global forests, no reliableglobal statistics are available for a wildfire duration time. More information
about duration time of wildfires would be needed so far.

119

July 2008, Thailand

MTSAT have thermal infrared sensor in spite of spatial resolution is
4km. By using MTSAT, we can analyze hourly features of wildfires (JMA,2003). Before MTSAT launched, there is no way to clarify the feature ofduration time of wildfires. Clarification of duration time of wildfire
contributes to the evaluation of CO 2 emissions by wildfires.
1.2 Objective
The objective of this research is as follows.
1. To evaluate relation between a scale of burning area and spatial
resolution by comparing ASTER, MODIS, and MTSAT which
spatial resolution is different each other.
2. To clarify the feature of duration time using MTSAT data
Myanmar, far east Siberia, and Sumatra.

2. METHODOLOGY
2.1 Wildfire duration time estimation model used in this study

Figure 1: Flowchart of wildfire duration time estimation using MTSAT.
Figure 1 shows the flowchart of wildfire duration time estimation with
MTSAT. This research consists of two parts; comparison of burnt areadelineation with ASTER, MODIS and MTSAT, the other is the evaluationof wildfire duration time using MTSAT data.
Firstly, three study areas were determined supplemented by hotspot
data with MODIS. Secondly, a bunch of satellite dataset was createdincluding ASTER, MODIS and MTSAT with different spatial resolutions
90m, 1km and 4km respectively. They were used to delineate burnt areas
and were carried out by using web-based processing systems(http://webmodis.iis.u-tokyo.ac.jp, http://webgms.iis.u-tokyo.ac.jp). Finally,
wildfire duration time was estimated with 72-hours time series behaviors of
MTSAT thermal infrared imagery by comparing a fire pixel with a non-firepixel.
2.2 Study areas
Study areas are determined by fire spots data by MODIS, vegetation
map by Boston University, and visual judgments from Google earth.

120

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Considering difference of size and vegetation, following three areas are
selected; evergreen broadleaf forest in Myanmar (March 23rd in 2007, 9653’E, 19-13’N), evergreen needleleaf forest in far-east Siberia (July 4th in2007, 139-26’E, 57-33’N), and evergreen broadleaf forest in Sumatra (Oct.
5th in 2006, 102-43’E, 0-43’S).

3. RESULTS AND DISCUSSIONS
3.1 Comparison of burnt area delineation with ASTER, MODIS andMTSAT(a) ASTER channel 14(b)Binary image(c) MODIS channel 31(d) MTSAT channel 1

Figure 2: Thermal infrared imagery of ASTER, MODIS and MTSAT. The
area of interest is 8x8 km2 corresponding to 4 pixels of MTSAT.
Figure 2 shows thermal infrared imagery of ASTER, MODIS andMTSAT. The area of interest is 8x8 km2 corresponding to 4 pixels of
MTSAT. Figure 2-(a) shows ASTER channel 14 imagery. A histogram of
ASTER channel 14 shown in Figure 2-(a) was used to determine a threshold
between fire pixels and non-fire pixels, and binary image was created asshown in Figure2-(b). The extracted fire-affected area is shown in whitecolors in the center of the image and area was estimated 1.5 km2. As acomparison, MODIS channel 31 imagery is shown in Figure 2-(c) over thesame area. Spatial distribution of MODIS has consistency with that of
ASTER. MTSAT channel 1 imagery shown in Figure 2-(d) shows a fairy
good results compared with ASTER and MODIS as well. A fire affected
pixel shown in an upper left highlighted in white color has 3K higher than

Evaluation of Wildfire Duration Time Over Asia Using MTSAT and MODIS

121

July 2008, Thailand

the other three non-fire pixels. It was found that this fire event with the sizeof 1.5 km2 is detected by 4km MTSAT thermal infrared imagery.
3.2 Estimation of wildfire duration time using MTSAT
Figure 3-(a) shows the location of intensive wildfire hotspot in
Myanmar. Figure 4-(a) shows time series variation of the land surface
temperature from MTSAT (channel1, 10 μ m) from March 23rd to 25th in2007. The hotspot was detected in March 23rd, the first day of the series, by
MODIS fire product. Time series variation from MTSAT shows thattemperatures of fire pixels transit higher than that of non-fire pixels. The
biggest difference is 2K at 14:00 in local time. The difference oftemperatures between fire pixels and non-fire pixels were gone during night
time. From this result, even though spatial resolution of MTSAT is poorer
than that of MODIS, time series variation of a thermal infrared channel of
MTSAT show significant difference to detect fire pixels because time
resolution is more frequently.
Figure 3-(b) shows locations of target pixels of time series variation
on evergreen needle leaf forests in Siberia. Figure 4-(b) shows time series
variation of the land surface temperature from MTSAT (channel1, 10 μ m)from July 3rd to 5th in 2007. The time when the wildfire was detected by
MODIS fire products is July 4th and July 5th. As the figure shows, both of afire pixel and a non-fire pixel show a similar time series variation in July
3rd. However, the fire pixel displays different behavior from normal pixels
in July 4th and July 5th. At the peak of the graph, the fire pixel shows about
3K higher temperatures than the non-fire pixel in July 5th. From thisinformation, the wildfire duration time is 10 hour in July 4th and 12 hour inJuly 5th.
Figure 3-(c) shows locations of target pixels of time series variation
on evergreen broadleaf forests in Sumatra. Figure 4-(c) shows time series
variation of the land surface temperature from MTSAT (channel1, 10 μ m)from Oct. 5th to 7th in 2006. The time when the wildfire was detected by
MODIS fire product is Oct.5th and Oct. 6th at fire pixels A and B. As thefigure shows, the peak of the time series variation at fire pixels A and B on
Oct. 5th and Oct. 6th is higher than a non-fire pixel C. From this figure,duration time of wildfire is 14 hours in Oct. 5th and 9 hours in Oct. 6th. At
Oct. 7th, both of the land surface temperature in pixel A, B, and C change in
the almost same way, so we estimate there is no wildfire in these pixels.

122

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

N

N

N

(a)Myanmar (Mar. 23-25,2007) (b)Far-east Siberia (Jul. 4-6,2007)(c)Sumatra (Oct. 5-7,2007)
Figure 3: Methodology of evaluation of fire duration time using MTSAT.
315

Mar.23Mar.24Mar.25(a)Myanmar (evergreen broadleaf forest)

Jul.4

Jul.5

Jul.6

(b)Far-east Siberia (evergreen needleleaf forest)

Evaluation of Wildfire Duration Time Over Asia Using MTSAT and MODIS

123

July 2008, Thailand

Oct.5

Oct.6

Oct.7

(c)Sumatra (evergreen broadleaf forest)
Figure 4: Time series variation of MTSAT thermal infrared imageries(channel 1 10.5 μ m).

4. CONCLUSION AND FUTURE WORKSIn this research, we have presented two types of research. Firstly wecompare burnt area delineation with ASTER, MODIS and MTSAT thatspatial resolution is different each other. Secondly, we estimate duration
time of three wildfires by using time series variation of MTSAT comparing
fire pixels and non-fire pixels. Our accomplishments are following three
things.
• Thermal infrared imageries of ASTER, MODIS, and MTSAT shows
consistent spatial distribution.
• MTSAT can be used to detect intensive wildfire that a an area isabout 1.5 km2 in this survey, even though spatial resolution of
MTSAT is 4km meanwhile that of ASTER is 90m.
• Duration time of intensive wildfire can be estimated by using visualjudgment from the difference of time series variation of fire pixels
and non-fire pixels.
In the future research, we have to consider following two things.
• Thermal infrared imageries of MTSAT have problems about
geometric correction. Therefore, when we will estimate wildfire
duration time automatically, precise geometric correction should beneeded• When we compare burnt area delineation with ASTER, MODIS andMTSAT, it is very hard to find an ASTER imagery which contains
burnt area because there are few ASTER imageries which containhotspots. We should consider using another high spatial resolution
data such as Landsat.

ACKNOWLEDGEMENT
This research is supported by JSPS (No. 19569002). The authors would liketo thank Dr. Vivarad Phonekeo for providing MODIS data at AIT in
Thailand.

124

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

REFERENCES
Glogal land cover mapping from MODIS: algorithms andearly results. Remote Sens. Environ. ,83(1-2), 287-302.
Giglio, L., Descloitres, J., Justice, C. O., and Kaufman, Y., 2003, An
enhanced contextual fire detection algorithm for MODIS. Remote
Sens. Environ., 87, 273-282. Japan Meteorological Agency, 2003.
JMA HRIT Mission Specific Implementation, Ver. 1.2.
Kaufman, Y. J., C. O. Justice, L. P. Flynn, J. D. Kendall, E. M. Prins, L.
Giglio, D. E. Ward, W. P. Menzel, and A. W. Setzer, 1998, Potential
global fire monitoring from EOS-MODIS. J. Geophys. Res., 103:
32215-32238.
Takeuchi, W., and Y. Yasuoka, 2005. Near-real time activefire mapping
over Asia using Aqua/Terra MODIS. Proceed. 26th Asian conf. on
remote sens. (ACRS 2005),Hanoi, Vietnam.
Takeuchi, W., T. Nemoto, T. Kaneko and Y. Yasuoka, 2007. Developmentof MTSAT data processing, distribution and visualization system on
WWW. Proceed. Int. symp. remote sens. (ISRS 2007), Jeju, Korea.
UNDP, UNEP, World Bank and WRI, 2001, World Resources
2000-2001, Elsevier Science, 87-102.

Evaluation of Wildfire Duration Time Over Asia Using MTSAT and MODIS

125

July 2008, Thailand

126

Joint Student Seminar on Civil Infrastructures

SHEAR BEHAVIOR OF PARTICLES WITHRESPECT TO BONDING STATEUSING PFC2D
SEON-AH JO, SEOK-KYU SONG,
SUN-AH JEONG and SEOK-WON LEE
Civil and Environmental System Engineering,
Konkuk University, Korea
asaca83@kokkuk.ac.kr
ssk81@konkuk.ac.kr
butterfly0523@hanmail.net
swlee@konkuk.ac.kr
ABSTRACT
Direct shear test was modeled using PFC2D in this study. Modeling
was performed with respect to vertical stress condition, relative density, andparticle shapes. Geometrical particle shape is represented by a combinationof circular shape, and influence of particle shape on crushing is studied
through relative comparisons between Clump (uncrushable) and Cluster(crushable) models. The results show that in Clump model, internal friction
angle was largest for triangular shape and smallest for square shape. Evenfor cases of a same shape, internal friction angle becomes smaller when thenumber of balls comprising the particle shape increases, because thesurface contour of the particle becomes smooth, reducing the interlocking
effect. In Cluster model, when bond strength is low, most of contacts arebroken during the stage of vertical stress application, and the model
becomes similar to that of one ball. However, when bond strength becomeslarger, the model approaches the Clump model in which particle damages
occur due to vertical stress and shear application, which in turn results in
reduction of peak shear stress. That is, shear resistance angle becomes
reduced, and also failure envelop curve becomes nonlinear, due to theparticle crushing.

1. INTRODUCTION
Granular materials are subject to static and dynamic loads during
construction works as they are parts of slope, embankment, foundation, or
pavement structures. They could be partially or fully crushed by the loads,
and such a crushing could cause additional subsidence and reduction inwater permeability by a great amount, and also alter friction angle that
represents interface shear strength. Accordingly, alteration of original
particles due to crushing could influence the stability of structurescontaining interfaces.

127

July 2008, Thailand

Factors influencing crushing of granular particles include particle size,
shape, distribution, relative density, etc. In terms of granular behaviors, it isimportant to analyze the influences of these factors on the granular crushing,and in this study such factors are characterized by numerical analysis from ashear resistance viewpoint. For the purpose, direct shear test was modeledusing PFC2D, which is a distinct element method program, and modeling
was performed with respect to vertical stress condition, relative density, andparticle shapes. Geometrical particle shape is represented by a combinationof circular shape, and influence of particle shape on crushing is studied
through relative comparisons between Clump (uncrushable) and Cluster(crushable) models. The results from the analyses are presented using stressdisplacement curves, and evolution of granular crushing are presented in atime sequence.

2. PARTICLE FLOW CODE MODELINGIn this study PFC2D based on distinct element method was employed inorder to simulate direct shear test by numerical analysis. PFC2D was
originally developed by Cundall(1995), and has been used widely in various
engineering fields. Unlike finite element method or finite difference methodmodeling where an object is modeled by continuous nodes or mesh elements,
distinct element method is based on motion and mutual interaction of
spherical particles, making it more suitable for simulating sand and earth
ground foundation visually.
Basically, PFC2D uses explicit method in arithmetic process, andexternal force, velocity, moment, and position of each granule are calculatedby the equation of motion. Using the force-displacement relationship at thecontact point of each particle, it is converted to interface strength, and thisprocess is repeated every moment along the time-step.

(a) Contact bond model(b) Parallel bond model

Figure 1: Particle bond models
Elements' bond models in PFC2D can be determined by user's
definition, and are classified into linear and nonlinear bond models based oncontact stiffness, and into contact bond and parallel bond based on particle
bond model. In the contact bond shown in Figure 1(a), bonding strength is128

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

represented by behaviors of one pair of spring in vertical strength and shear
strength at the contact area which is represented as a minute point between
the two elements. In the parallel bond shown in Figure 1(b), the contact area
is represented by a cylinder or a rectangular depending on whether it iscylindrical shape or spherical shape, respectively. While only the force istransmitted at a minute contact point in the case of the contact bond, theforce and the moment are transmitted together in the parallel bond,simulating strong bonding found in cement or stiff materials. If any specificbonding model is not defined, slip-separation model is applied in which
frictional forces exists and slip is allowed depending on the shear
component of the applied force.

3. MODEL CONSTRUCTION AND ANALYTICAL PROCESS
3.1 Direct shear model
In this study, modeling is performed by numerical analysis based on
PFC2D in order to analyze shear behavior characteristics and shear
mechanism with respect to particle crushing at the interface between two
granular materials. Size of shear box was determined as 6cm in width and
2cm in height, based on general shear test apparatus.
Figure 2 shows a schematic of direct shear test model. In the model,
upper box comprises four walls (ED, EF, FG, GH), and walls ED, FE andGH are fixed. On GF wall, vertical stress is calculated by Fish Function
from contacting force between the wall and particle according to servocontrolled system, in which a certain level of stress is maintained. Sheardisplacements are resulted through horizontal movements of four walls (HA,
AB, BC, CD) comprising the lower box, and the shear stress is calculated as
contact force between the wall AB and particles interfacing this walls.
Figure 2(b) shows the shear boxes and distribution of contact forces after
the shearing is completed.
N
G

F
Upper box
E

H

D

A
T

Lower box
BC(a) Schematic of direct shear test(b) PFC2D direct shear model
Figure 2: Direct shear model
3.2 Test sample preparation
Input parameters for particles to be used in PFC2D include size,
stiffness, friction coefficient, and bond strength. Particles for modeling in

Shear behavior of particles with respect to bonding state using PFC2D

129

July 2008, Thailand

this study apply the blasting sands, as the physical characteristics are listed
in Table 1. As for the particle size, a value corresponding to D50 was chosenon grain size distribution curve for blasting sand and applied to all the balls,
and number of particles generated as such is 2,474. 0.75 was applied for
friction coefficient, and other input parameters were chosen throughnumerical analysis calibration, and the resulting values are listed in Table 2.
Table 1: Basic physical characteristics of blasting sandBlasting sandRmin (mm)0.075
Rmax (mm)2
D50 (mm)
0.73
emim
0.7
emax
0.95
37
Friction angle (°)
Friction coefficient(μ)
0.754Table 2: Input physical parameters in PFC2D
Micro properties
Value
3
Density (kg/m )2,650
Normal stiffness (N/m)
1× 10 8
Shear stiffness (N/m)
1× 10 8Friction coefficient (μ)
0.75Gravity (m/s2)
9.81
Rmin (mm)0.075
Rmax (mm)1
Initial porosity
0.166
Ball number
2,474
Parallel
Normal2 × 10 5 or
(Pa)
bond
8 × 10 5
Shear (Pa)2 × 10 5 or
8 × 10 5

3.3 Conditions for analysis

Table 3 lists numerical analysis methods and conditions employed inthis study. Direct shear models with respect to granular form condition areclassified into one-ball, clump, and cluster. Here, one-ball model refers tosingle particle model of spherical shape, clump model refers to a state inwhich two or more spherical particles have permanent contacts without
involving any crushing at the contact points, and cluster model refers to astate in which two or more spherical particles are in contact mode by acertain bonding stress and then get broken when a higher stress is applied on
them.
In one-ball model, conditions were differentiated between loose stateof relative density of 20% and dense state of relative state of 90%, and then130

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

vertical stress conditions of 50, 100, 200, and 300 kPa were applied in the
numerical analysis. In clump and cluster models, vertical stress of 100 kPa
was applied in dense state of relative density of 90%, and numerical analysis
was performed for each granular formation. In clump and cluster models asshown in Figure 3, granular formations are classified into rectangular form((a), (d)), triangular form ((b), (e)), and square form ((c), (f)), constructed bybonding of 2, 3, 4, 6, and 9 spherical granules, where each ball is assumed
to be a cylinder of an unit length, and sum of the areas of balls applied is asame for all the cases. For cluster model, bond strength was set at 2 × 10 5
and 8 × 10 5 Pa in the numerical analysis.
Table 3: Methods and conditions for numerical analysis
each vertical stress 50, 100,
relative density 20%
200, 300 kPa
One balleach vertical stress 50, 100,
relative density 90%
200, 300 kPa
Directeach 2ball, 3ball, 4ball,
Shear
Clump
particle formation
6ball_R, 6ball_T, 9ballModelbond strength :2×105 Pa
particleeach 2ball, 3ball, 4ball,
Clusterformation
6ball_R, 6ball_T, 9ballbond strength :5
8×10 Pa(a) 2ball(b) 3ball(c) 4ball(d) 6ball_R(e) 6ball_T(f) 9ballFigure 3: Particle formation
4. ANALYSIS RESULTS
4.1 Characteristics of shear behavior of one ball modelA study was conducted on change of shear stress characteristics of
direct shear model made of one ball while varying conditions of verticalstress and relative density. Vertical stress was set at 50, 100, 200, and 300
kPa with maximum displacement of 6mm. Figure 4 shows stressdisplacement curves obtained from the analyses. Reliability of this model
was established by confirming that maximum shear stress value, andhorizontal displacement point where that maximum shear stress is occurring,increase when vertical stress is increased in stepwise. Also, as results on
shear stress characteristics per relative density, it shows a tendency of loose
condition where clear peak point does not exist when relative density is 20%,as shown in Figure 4(a), and it shows a tendency of dense condition where a

Shear behavior of particles with respect to bonding state using PFC2D

131

July 2008, Thailand

160

160

140

140

Shear Str es s ( kPa)

S hear S tr es s ( kPa)

peak point exists when relative density is 90% in stress-displacement curve,
as shown in Figure 4(b).

120
100

300kP a80
60

200kP a40

100kP a50kP a20

300kP a120
200kP a100
80
60

100kP a40

50kP a

20

0

0
0

2

4

6

0

2

4

H or iz ont al Dis placem ent ( m m )H or iz ont al Dis placem ent ( m m )(a) Relative density 20%(b) Relative density 90%

6Figure 4: Shear stress with respect to vertical stress

Mohr-Coulomb Failure envelops are shown in Figure 5 for relative
density of 20% and 90%, respectively, and the curves are used to find out
the change in maximum shear stress under vertical stress condition. Here,internal friction angles were 27.8°, 18.7° for the relative density of 90% and20%, respectively. It was confirmed that the internal friction angles are
somewhat lower in this study, as compared to the values 31.9° , 37.9°
obtained for relative density of 25% and 75%, respectively, for the standard
Joomoonjin sands(Uhm et al., 2004). This result seems to be related to a factthat the particles in this study are spherical with smooth surface, andaccordingly do not reflect the shape and surface roughness of natural coarse
granules in this analysis. Accordingly, it is desirable to perform the analysis
while varying the shape of the particle variously in order to obtain precise
analytical results, and such improved analysis is described in the following
section.

Peak Shear Stress ( kPa)200

φ ( dense) = 27.8°
φ ( loose) = 18.7°

150

100

50

0
0

50

100

150

200

250

300

Normal Stress ( kPa)

Figure 5: Failure envelope

132

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

4.2 Characteristics of shear behavior of clump model

In PFC2D, the ball is assumed to be a sphere or cylinder, thus limiting
the accuracy obtainable from the analysis for actual particles that possess
geometrically complicated shapes. Clump concept is one of solutions foravoiding the limitation. In clump model, a number of spherical particles arebound as a group, and geometrical shape of the particle is represented while
maintaining the contacts at the contact points between the particles within
the group. The group behaves as one particle element, and the contact points
within the group are excluded in the calculation process, and analysis iscarried out only for one the contact point between groups, thus shortening
the time to conduct the analysis.
In this section, analysis was done to find out the influence of particle
shapes on shear stress characteristics, while excluding particle crushing,based on clump principle, using six particle shapes as shown in Figure 3.
The stress-displacement curves for clump model were obtained as shown in
Figure 6. In all the shapes, peak value was reached after a certain range ofdisplacement, after which the stress decreases before settling on a residual
stress condition. Figure 7 shows Mohr-Coulomb failure envelope perparticle shape, and internal friction angle for each shape is listed in Table 4.
When the particle shape is triangular, the peak shear stress and internal
friction angle are maximum as shown in Figure 3(b), with 155 kPa and54.7 ° , respectively, while the values were minimum when the shape issquare as shown in Figure 3(f), with 113 kPa and 46.5°, respectively. When
comparisons are made between (a) and (d), (b) and (e), and (c) and (f), it
was confirmed that the values became smaller when the number of particles
is larger. The result can be understood from the view point of surface
roughness of particles. That is, even for a same shape, when the number ofballs is fewer, the surface contour varies more, thus becoming more rougher,
while in the opposite case the contour becomes smoother. Larger variationin the contour of the particle surface increases interlocking condition, thusincreasing peak shear stress and friction angle as a result.
180

2ball
3ball
4ball
6ball_R
6ball_T
9ball

Shear Stress ( kPa)

160
140
120
100
80
60
40
20
0
0

1

2

3

4

5

6

Horizontal Displacemet ( mm)Figure 6: Stress-displacement curves regarding particle shapes

Shear behavior of particles with respect to bonding state using PFC2D

133

July 2008, Thailand

500
450

2ball
3ball
4ball
6ball_R
6ball_T
9ball

Shear Stress (kPa)

400
350
300
250
200
150
100
50
0
0

50

100

150

200

250

300

Normal Stress (kPa)

Figure 7: Failure envelope regarding particle formation
Table 4: Internal friction angle regarding particle
Particle formation
Internal friction angle(ϕ)
2ball
50
3ball
54.73
4ball
46.94
6ball_R
49.05
6ball_T
52.57
9ball
46.48

Numerical analysis based on clump principle has the advantage ofshortened analysis time, but has a shortcoming of not considering theinfluence of particle crushing. That is, the assumption that balls in the model
are bound by infinite contact strength cannot handle cases when particles arecrushed. In order to resolve this limitation, cluster concept is applied inwhich the concept of particle crush is introduced.
4.3 Characteristics of shear behavior of cluster model

In the clump principle, there is a limitation that balls in the model arebound by infinite contact strength, thus it cannot handle cases whenparticles are crushed. Accordingly in this section, cluster concept is
introduced in which certain level of bond strength is applied and the contact
is to be destroyed when stress beyond the level is applied externally. The
same six particle formations of 2ball, 3ball, 4ball, 6ball_R, 6ball_T, and9ball conditions were employed, and parallel bond model was applied
regarding the bond among the balls within one group in performing analysis.
Change on shear stress with respect to bond strength was found out in order
to select a proper bond strength that may represent crush strength of coarse
granular soil, and the results were obtained regarding relationship between
peak shear stress and bond strength as shown in Figure 8. Here, vertical134

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

stress of 100kPa and relative density of 20% were applied. As shown by the
curves, when bond strength is less than 1× 10 5 Pa, particle bonds are mostly
crushed at a stage of vertical stress application, and shear strength becomes
constant, instead of increasing. On the other hand when bond strength
exceeds 1× 10 6 Pa, particle bonds are not crushed even at a stage of verticalstress application, exhibiting a certain level of shear strength value.
Accordingly, in this analysis, bond strength values of 2 × 10 5 Pa and8 × 10 5 Pa were taken, corresponding to 20% and 80% values, respectively,
between 1× 10 5 Pa and 1× 10 6 Pa, to study influences regarding particle
crushing.

Peak S hear S tr es s ( kPa)

120
100
80

60
40
20
0
1.E +00

1.E +01

1.E +02

1.E +03

1.E +04

1.E +05

1.E +06

1.E +07

1.E +08

1.E +09

B ond S tr ength ( Pa)

Figure 8: Peak shear stress regarding bond strength

Shear stress test results are shown in Figure 9 for two bond strength
conditions of vertical stress 100kPa and relative density 20%, per particle
formation. In all the models, peak shear stress value increases as bondstrength increases, and breaking points appeared clearly. That is, when bondstrength is small, the bond between the balls is destroyed even by a small
increase in stress, reducing the influence of particle formation factor on
shear stress, while when bond strength becomes larger, the influence ofparticle formation factor on shear stress becomes larger and breaking points
appear clearly. Under a same bond condition, shear stress shows somevariations with respect to particle formation, and this seems to be related tothe size of balls comprising the particle.

Shear behavior of particles with respect to bonding state using PFC2D

135

July 2008, Thailand

2ball_2e5
4ball_2e5
6ball_T_2e5

120

140

3ball_2e5
6ball_R _2e5
9ball_2e5

S hear Str es s ( kPa)

S hear S tr es s ( kPa)

140

100
80
60
40
20

2ball_8e5
4ball_8e5
6ball_T_8e5120

3ball_8e5
6ball_R _8e5
9ball_8e5

100
80
60
40
20

0

0
0

1

2

3

4

5

6

0

1

2

3

4

5

H or iz ontal Dis placem ent ( m m )H or iz ontal Dis plac em ent ( m m )(a) Bond strength 2 × 10 5 Pa(b) Bond strength 8 × 10 5 Pa

6Figure 9: Shear stress characteristics with respect to bond strength
4.4 Comparison between clump model and cluster model

In this section, results from clump and that from cluster are compared,
as depicted in Figure 10. Peak shear strength from clump model is larger
than that obtained from cluster model on two bond strengths. This isbecause, in clump model, particle crush does not occur owing to the infinite
strength assumed on the contacts between balls, while, in cluster model,
particle crush occurs, allowing influences from crushing. Here, MohrCoulomb Failure envelop is found with 2ball model in particular, as shownin Figure 11. The curve is near linear in clump model, while it is nonlinear
in cluster model. This agrees with prior result (Bolton, 1986; Feda, 2002)
which says that failure envelop expressing peak shear strength is nonlinear
because shear resistance angle is reduced owing to particle crush.
Accordingly, it is concluded from these results that it is preferred to apply
cluster model in studies involving particle crushing.

160

160
2 b a ll140
S h e ar S t r e s s ( k P a)

S h e ar S t r e s s ( k P a)

140
120
100

2 b a ll_8 e580
2 b a ll_2 e5

60
40
20

100
80
6 b a ll_R _8 e560

6 b a ll_R _2 e5

40
20

0

0
0

1

2

3

4

H o r iz o n t al D isp lace m e n t ( m m )(a) 2ball136

6 b a ll_R

120

5

6

0

1

2

3

4

5

6

H o r iz o n t al D isp lace m e n t ( m m )(b) 6ball_R

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

160

160
6 b a ll_T

140

120

S h e ar S t r e s s ( k P a)

S h e ar S t r e s s ( k P a)140
4 b a ll

100
80

4 b a ll_8 e560
40

4 b a ll_2 e5

20

120
100
6 b a ll_T _8 e58060

6 b a ll_T _2 e5

40
20

0

0
0

1

2

3

4

5

6

0

1

H o r iz o n t al D isp lace m e n t ( m m )2(c) 3ball

4

5

6

5

6

(d) 6ball_T

160

160

140

140

120

S h e ar S t r e s s ( k P a)

S h e ar S t r e s s ( k P a)3

H o r iz o n t al D isp lace m e n t ( m m )4 b a ll

100
80

4 b a ll_8 e560
40

4 b a ll_2 e5

20

120

9 b a ll

100
80
60

9 b a ll_8 e5
9 b a ll_2 e5

40
20

0

0
0

1

2

3

4

5

6

0

1

H o r iz o n t al D isp lace m e n t ( m m )

2

3

4

H o r iz o n t al D isp lace m e n t ( m m )(e) 4ball(f) 9ballFigure 10: Comparison of Clump and Cluster shear stress values

400

clump

Shear Stress ( kPa)

350

cluster

300
250
200
150
100
50
0
0

50

100

150

200

250

300

Normal Stress ( kPa)

Figure 11: Failure envelope
5. CONCLUSIONS

Direct shear test was modeled using PFC2D in this study. Modeling was
performed with respect to vertical stress condition, relative density, andparticle shapes. Geometrical particle shape is represented by a combinationof circular shape, and influence of particle shape on crushing is studied
through relative comparisons between clump (uncrushable) and cluster(crushable) models. Conclusions obtained through this study are as follows:

Shear behavior of particles with respect to bonding state using PFC2D

137

July 2008, Thailand

1. In the case of One-ball model, when vertical stress increases
stepwise, peak shear stress value and the horizontal displacement points
where the peak shear stress occur, keep increasing in direct shear model. It
shows a tendency of loose condition where clear peak point does not appear
when relative density is 20%, while it shows a tendency of dense condition
where a peak point appears when relative density is 90%, in which breaking
points appear when a certain amount of horizontal displacement is applied.
This result is similar to the typical results obtained from laboratory direct
shear tests, establishing the reliability of the present numerical analysis.
2. In the case clump model, larger values were obtained for peak shear
stress as compared to one-ball model, owing to an influence of particle
formation, and internal friction angle was largest for triangular shape andsmallest for square shape. Even for cases of a same shape, internal friction
angle becomes smaller when the number of balls comprising the particle
shape increases, because the surface contour of the particle becomessmooth, reducing the interlocking effect.
3. In the case of cluster, when bond strength is low, most of contacts
are broken during the stage of vertical stress application, and the model
becomes similar to that of one ball model. However, when bond strength
becomes larger, the model approaches the clump model in which particle
damages occur due to vertical stress and shear application, which in turnresults in reduction of peak shear stress. That is, shear resistance angle
becomes reduced, and also failure envelop curve becomes nonlinear, due tothe particle crushing.

ACKNOWLEDGEMENTS

This work was supported by the Korea Research Foundation Grant fundedby the Korean Government (MOEHRD) (KRF-2007-331-D00475).

REFERENCES

Barrett, P.J., 1980, The shape of rock particles, a critical review,
Sedimentology, 27, 291-303.
Bonton, M.D., 1986, The strength and dilatancy of sands. Geotechnique,Vol. 36, No. 1, 65-78.
Cho, G.C., Dodds, J.S., and Santamarina, J.C., 2006. Particle shape effects
on packing density, stiffness, and strength: natural and crushed sands,
Journal of Geotechnical and Geoenvironmental Engineering, ASCE,
Vol. 132, No. 5, 591-602.
Coop, M.R., Sorensen, K.K., Freitas, T.B., and Georgoutsos, G., 2004.
Particle breakage during shearing of a carbonate sand. Géotechnique,Vol. 54, No. 3, 157-164.
Feda, J., 2002. Notes on ter effect of grain crushing on the grnular soil
behavior. Engng Geol., Vol. 63, No. 1, 93-98.
Itasca Consulting Group, Theory and Background.

138

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Krumbein, W.C., 1941. Measurement and geological significance of shapeand roundness of sedimentary particle. J. Sediment. Petrol., 11(2), 6472.
Krumbein, W.C. and Sloss, L.L., 1963. Stratigraphy and sedimentation, 2ndEd., Freeman and Company, San Francisco.
Lee, K.L. and Farhoomand, I., 1967. Compressibility and crushing of
granular soil in anisotropic triaxial compression. Can. Geotech. J.,
vol.4, 68-86.
Powers, M.C., 1953. A new roundness scale for sedimentary particles. J.
Sediment. Petrol, 23(2), 117-119.
Wadell, H., 1932. Volume, shape, and roundness of rock particles., J. Geol.,40, 443-451.

Shear behavior of particles with respect to bonding state using PFC2D

139

July 2008, Thailand

140

Joint Student Seminar on Civil Infrastructures

BEHAVIOR OF SOFT GROUNDINSTALLED WITH EXPANDING
VERTICAL DRAIN
PHUONG TUNG HOANG1, JAI-BEOM SHIM2,JIHO PARK3, SEONG-HYEON SHIM4
and YOUNG UK KIM5
1,3,5
Department of Civil and Environmental Engineering,
Myongji University, Korea
2,4Samsung Corporation, Engineering and Construction, Korea
tungphhoang@gmail.com
ABSTRACTThe behaviors of soft soil were investigated by using two types ofvertical drains through centrifuge modeling. The Improvement methods
involve Sand Compaction Piles (SCPs) method and Expanding Vertical
Drains (EVDs) method which was newly developed in the lab. The
behaviors of soft soil such as displacement, pore water pressure and watercontent were observed and collected. The improvement processes of treatedsoil (with SCPs and EVDs) and non-treated soil were compared andpresented in details at conclusions.

1. INTRODUCTION
Sand Compaction Piles (SCPs) method now is widely being used in
marginal sites to improve stability, to control liquefaction, and to reduce
settlement of various infrastructures. These piles can significantly enhance
the pore water pressure-dissipation process and decrease the consolidation
time when built in soft clay. In South Korea, the SCPs were first used in1984 for the construction of the Kwang Yang Steel Mill complex and thismethod has advanced and found a wider application in Japan (Barksdale andTakefumi, 1991; Enoki et al., 1991).
Expanding Vertical Drains (EVDs) is, however a new method toimprove soft soil which is suggested by Myongji University. The EVD’s
drainage principle is similar to Prefabricated Vertical Drains (PVDs). The
PVDs devices are installed into the soft clay to create the artificial drainage
paths. The use of PVDs along with precompression has the sole purpose of
shortening the drainage path (distance to a drainage boundary) of the porewater, thereby accelerating the rate of soft clay consolidation. EVD is a highwater absorbability device and made of an expanding material whensubjected to water (Photo 1). Installation of EVD might create the increased
water flow path due to expanding. In addition, the adjacent soil mass will becompressed by the EVDs along the horizontal direction.

141

July 2008, Thailand

This paper intended to compare the ability of soft soil treatment
between EVDs and SCPs through a series geotechnical centrifuge tests. The
results of experiment tests were discussed with special reference to thesettlement, the pore water pressure and the moisture content of treated-soft
clay (with SCP and EVDs) and non-treated soft clay.

Photo 1: Expanding material applied to EVD

2. EXPERIMENTAL PROGRAM
2.1 Test cases
Three kinds of tests were carried out and are listed in Table 1.
Improvement ratio is defined as the ratio between the total cross sectional
area of the columns and the improved area. The improvement ratio wasabout 12% for all tests and the value of improvement ratio was arbitrarychoosen in this research. The material of treating column was varied inevery test case.

Case 1

Table 1: Test case
Case 2

Case 3

Improvement
ratio (%)

0

12

12

Improvement
methodNontreated

Sand compaction
pile(fine sand)Expanding verticaldrain(paper towel)

2.2 Preparation of soft clay bed
The slurry used in the centrifuge tests was preparation by mixing theclay with de-aired water until its moisture content reaches about 115%. The
slurry was also boiled in a container for about 10 hours in order to remove
void air and to obtain homogeneous slurry. During boiling slurry process,clay and water were stirred regularly. After getting the slurry homogeneousslurry from the boiling process, this soft clay was self-consolidated bycentrifuge rotation velocity of 173 rpm corresponding to 40 g for 8 hours.
The soft ground deposit was made as following.

142

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

1. 5 cm thickness fine sand layer was compacted and embedded on thebottom of swing-up box. This sand layer will resist the lateral movement ofclay layer above and another function of this deposit is an under permeable
layer.
2. The homogenous slurry was poured over the sand layer. The heightof this layer reached 15 cm.
3. This ground was consolidated by itself during 8 hours in centrifuge
to make the normally consolidated ground whose shear strength increased
linearly with the depth. The final thickness of the soft ground was around 10cm.
2.3 Preparation of Sand Compaction Pile (SCP) model
Joomoonjin sand was used for material of SCP. A pile which has aremovable core was device to install SCP into soft clay. During SCP
installation process, the sand material was vibrative compacted by vibrationrod. The SCP’s has 20 mm diameter and 100 mm height. The vertical piles
were installed in triangular pattern, with center to center spacings of 3 cm. A
thin sand layer was laid on the clay surface to get a hardness surface andtwo linear variable displacement transducers (LVDTs) were set above torecord settlement during the test. Additional two pore pressure transducers(PPTs) were installed at prescribed locations. The arrangement of SCPs in
this test is shown in Figure 1a. Figure 1b shows the location of alltransducers used in the test.

Sand layer

1.0

PPT

Soft Clay layer

10.0

Vertical drain device

Sand layer

5.0

LVDT

(b)

Vertical drain
device4.0 3.0 3.0

20.0

60.0

3.0 3.0 3.0

30.0

(a)

(unit: cm)

Figure 1: Schematic view of model ground
2.4 Preparation of Expanding Vertical Drain (EVD) model
EVDs which were installed directly in this test are paper expanding
vertical drain. A series of paper (textile fabric material) towels having very
high water absorbability was used to make an EVD. The dimension of paper
towel piece is 20 mm diameter and 10 mm thickness. EVDs were made bylink 5 pieces through vertical side of them to get a device which has 10 mmthickness, 20 mm width and 100 mm height which is shown in Photo 2. The
Behavior of Soft Ground Installed with Expanding Vertical Drain

143

July 2008, Thailand

paper pieces should be kept absolute dry before using in centrifuge test. The
paper columns were installed along vertical direction by a long pin device.
EVDs will not be folded and clay mass is least disturbed by using this pin
device during installation process. The location of EVDs is triangularpattern similar to the aforementioned application SCPs. The LVDTs and
PPTs were also set on the modeling among the pile group along thedetermined positions.
2.5 Preparation of Non-treated modelingAfter pre-consolidation, the moisture content reduced from 115% toabout 65% and the settlement of model was about 5 cm. The geo-centrifuge
was stopped and set up LVDT devices on the clay surface, PPT equipments
inside the clay deposit. A thin sand layer was also laid over the modelsurface.
2.6 Geo-Centrifuge running procedure
All of models were pre-consolidated under 40 g for about 8 hours.
During pre-consolidation test, the ground displacement was checked. And
three models gave about 5 cm settlement after pre-consolidation. After the
pre-consolidation was completed, the model box was stopped, water content
of clay was checked, the ground improvement methods were applied and themeasurement gauges such as PPTs (Tokyo Sokki Kenkyujo KPC-500kPa)
and LVDTs (CDP-25) were set at the discussed positions. Each PPT was
filtered with a saturated porous stone to measure the pore water pressure andto protect the silicone diaphragm of transducer. Two linear variable
differential transducers had 2.5 cm length capacity. After setting, thecentrifuge ran during 15 minutes under the 10 g to check the transducers
connecting and 1 hour under the 20 g to remove the influence of stressrelease. The improvement process was applied under 220 rpm
corresponding to 65 g during 12 hours. After finished process, the data ofdisplacement and pore water pressure of three test models were colleted byCampbell Scientific_CR1000 dataloger.

3. RESULTS AND DISCUSSION
3.1 Settlement
The relationship between the settlements at the surface of the model
ground with time is shown in Figure 2. This figure shows that the amount ofsettlement of the improved ground installed with the EVDs is much lessthan that with the SCPs and the displacement value of the non-treatedground is highest.
1. At the initial settlement, the displacement values of three models
went up rapidly. The amount of settlement shot up dramatically from 0 cm
(at start time) to 1.47 cm (at 5000seconds elapse time) in non-treated model.

144

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

At that time, the rising of displacement value is from 0 cm to 0.83 cm andfrom 0 cm to 0.57 cm for SCPs and EVDs model, respectively.
2. The EVDs model reached to consolidation settlement fastest, thesecond is SCPs model and the third is non-treated model. The amount of
displacement rise gradually and slightly to become a steady line that is fairly
parallel with horizontal axis and the final settlement value of non-treatedmodel is 1.73 cm, of SCPs model is 1.23 cm, and of EVDs is 0.81 cm.
From these results, it can be concluded that the behavior of
consolidation strongly depends upon the material of ground improvement
methods. Photo 2 shows the expanded drainage after the test. Changed
shape of the EVD and SCP tests are seen in photo 3 and photo 4,
respectively.
E la p s e tim e (s e c )
0 .0

0 .0

5000

10000

15000

20000

25000

30000

35000

40000

45000

0 .2

SCP

0 .4

EVD
N o n -T re a te d

Settlement (cm)

0 .6
0 .8

EVD

1 .0
1 .2

SCP

1 .4

Non-treated

1 .6
1 .8
2 .0

Figure 2: Settlement – time curves of model ground

After

BeforePhoto 2: Expanding vertical drain shape
Behavior of Soft Ground Installed with Expanding Vertical Drain

145

July 2008, Thailand

Photo 3: EVDs model

Photo 4: SCPs model
3.2 Dissipation of pore water pressure
Figure 3 shows the relationship between the pore water pressure andthe elapsed time at each centrifuge tests. The pore water pressuresdeveloped by loading of the consolidation pressure are different from eachmodel.
1. At the start time of these tests, the pore water pressure generated byapplied centrifuge stress shots up dramatically, hitting the peak at 60.71,
50.11 and 40.22 kPa for Non-treated, SCP and EVD model respectively.

146

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

2. After that, the pore water pressure gradually dissipates over along
period time. The speed of dissipation of EVDs model is fastest and its final
value is lowest in this test.

7 0 .0 0
SCP
EVD
N o n - T r e a te dPore water pressure (kPa)

6 0 .0 0
5 0 .0 0
4 0 .0 0

Non-treated

3 0 .0 0

SCP

2 0 .0 0
1 0 .0 0

EVD

0 .0 00

5000

10000 15000 20000 25000 30000 35000 40000 45000
E la p s e tim e (s e c )Figure 3: Pore water pressure – time curves of the ground3.3 Moisture content
Finally, the centrifuge was stopped after 12 hours and the moisture
content was checked at several locations at each test. The averaged watercontent values were shown in the Table 2.

Moisture content (%)
InitialAfter pre-consolidation
After ground improvement

Table 2: Moisture content
Non-treated
SCPs
115.5
112.3
64.21
67.43
45.12
30.14

EVDs
113.4
65.85
22.75

Table 2 shows that after ground improvement method used, the watercontent in EVDs case is lowest and it rises up in SCPs and non-treated cases,
respectively.

4. CONCLUSIONS
From the results of the geo-centrifuge model test, the consolidation behaviorof the EVDs and SCPs ground improvement method and non-treated clay
ground is summarized as follows.
1. The consolidation behavior of the clay ground strongly depends on
the improvement material. The settlement of EVDs case is the least and it
can reach the consolidation settlement earliest. Then the EVDs method canincrease consolidation ratio, reduce the settlement of soft ground and thesecondary consolidation time.

Behavior of Soft Ground Installed with Expanding Vertical Drain

147

July 2008, Thailand

2. The pore water pressure dissipated rapidly in clay and the moisture
content was also lowest when EVDs was installed. From high absorbability,
EVDs can reduce the pore water significantly to increase the consolidation
process in clay mass.
3. The horizontal expanding of EVDs is an advantageous point toground treatment. When using EVDs, the clay ground is not only
consolidated by vertical direction but also compressed with horizontal sideby the expanding. By applying EVDs device, the clay deposit will besqueeze along two directions to increase the hardness and reduce theconsolidation time.
4. Otherwise, the other expectations of EVDs are low cost andenvironmental friendliness. The material of EVDs is recycled paper or
textile fabric which can be prefabricated in high quantity productions. Thenthe cost of EVDs is also lower than sand or the other natural materials.
However, the EVDs has a drawback which is its bearing capacity will
reduce because the material will be disintegrated in clay environmental for
long time period.

REFERENCES
US. Department of Transportation, Federal Highway Administration(August, 1986). Prefabricated Vertical Drains – Vol.1: Engineering
Guidelines, Report No. FHWA/RD-86/168.
J.B.Jung & T.Moriwaki, N.Sumioka, O.Kusakabe. Consolidation behavior
of composite ground improved by sand compaction piles, Centrifuge
98, Kimura, Kusakabe & Takemura (eds) 1998 Balkema, Rotterdam,
ISBN 90 5410 986 6, pp.825-830.
Y.W.Ng, F.H.Lee & K.Y. Yong. Development of an in-flight Sand
Compaction Piles (SCPs) installer, Centrifuge 98, Kimura, Kusakabe& Takemura (eds) 1998 Balkema, Rotterdam, ISBN 90 5410 986 6,
pp.837-843.
H.Hashizume, Y.Okochi & J.Dong, N.Horii, Y.Toyosawa & S.Tamate.
Study on the behavior of soft ground using Deep Mixing Method by
low improvement ratio, Centrifuge 98, Kimura, Kusakabe &Takemura (eds) 1998 Balkema, Rotterdam, ISBN 90 5410 986 6,
pp.851-856.
Thomas Michael WEBER, Development of a sand compaction pile
installation tool for the geotechnical drum centrifuge, XVI Euro
Young Geotechnical Engineers Conference, 8-11 July 2004, Vienna
Austria.
David Muir Wood, 2004. Geotechnical Modeling – Centrifuge modeling,
Version 2.2, pp.269 – 307.
Braja M. Das, 1999. Principles of Foundation Engineering, Fourth edition,
pp.796-820.

148

Joint Student Seminar on Civil Infrastructures

UTILIZING HETEROGENEOUS
ENGINEERING IN CONCRETE
MATERIAL INNOVATIONS FORSUSTAINABLE DEVELOPMENT1MICHAEL HENRY1 and YOSHITAKA KATO2
Department of Civil Engineering, University of Tokyo, Japan
2
International Center for Urban Safety Engineering,
Institute of Industrial Science, University of Tokyo, Japanmwhenry@iis.u-tokyo.ac.jp
katoyosh@iis.u-tokyo.ac.jp

ABSTRACT
Concrete may be thought of as an artifact composed of media
transformed by the transcription of design information. This design
information traditionally includes only engineering experience. However, inorder to improve the sustainable practices of the concrete industry, as wellas maintain competitiveness, the concrete industry must consider how toinclude the knowledge of other fields, such as sociology, economics, politics,
and so forth when developing new technologies. Heterogeneous engineering
is a term used by sociologist John Law to describe an approach totechnological innovation which not only considers traditional engineering
philosophy, but the integration of social, political, and other systems asnecessary for successful technological innovation.
Sustainability will drive changes in the way the concrete industry andconcrete construction operate. Utilizing heterogeneous engineering forintegrating new actors in the development of new concrete technology andinnovations will be necessary for their successful implementation.

1. INTRODUCTION
Concrete is a critical component for constructing the infrastructurenecessary to provide society with basic safety and living requirements. As
human populations continue to grow and urbanize, so too will the demandfor infrastructure increase, resulting in increased utilization of concrete tomeet that demand. Therefore, the concrete industry should become a leader
in promoting sustainable development as a design philosophy to enhance thelongevity and quality of our construction works while minimizing theirimpact on society and the environment.
Unfortunately, until now concrete has been developed primarily
considering an engineering perspective. In order to strengthen the149July 2008, Thailand

competitiveness of concrete as a construction material, as well as promotesustainability, concrete engineers must look beyond their traditional fields.
In this paper, social theory of technology is proposed as a means forstudying how to expand the networks which concrete engineers utilize whendeveloping technological innovations. This theory is then applied to thedesign process for concrete artifacts, considering the input of actors fromother fields in the design process.

2. HETEROGENEOUS ENGINEERING
Concrete is a technology, just as bicycles or guided missiles aretechnologies, and each of these has its own unique history of innovation anddevelopment. In order to understand the reasons for technologicaldevelopment, sociology should be applied. The theory of the social
construction of technology (SCOT) is used by sociologists of technology to
explain technological innovations. SCOT generally focuses on how new
artifacts are shaped. Technological development is driven by theinteractions between the social groups involved, rather than other factors
such as market demand. These social groups represent different perspectives
on the problems related to the innovation process, as each group has its
unique interests. As a result of these diverse interests, negotiation between
actors occurs in order to develop the technology. Furthermore, thetechnology is considered fully developed when it is accepted as such bythose who developed it (Pinch and Bijker, 1987).
In order to achieve successful innovation, John Law proposed that
innovators must be more than just engineers or scientists; that they needed
to become “heterogeneous engineers” (Law, 1987). Heterogeneous
engineers gather not only technological knowledge, but attempt to create
networks which contain the people, skills, and artifacts necessary to achieve
successful technological development. This network-building derives from
Bruno Latour and Michael Callon’s “actor-network theory,” which studies
the formation of networks consisting of both human and non-human actors
during times of change (Latour, 2005). Successful engineering, as explainedby Donald MacKenzie (borrowing from Law), involves building networks
which bind together the human and organizational with the technological(MacKenzie, 1987).

3. CONCRETE & SUSTAINABILITY
3.1 Development of concrete technology
Concrete material and infrastructure may be thought of as artifacts.
These artifacts are created from raw materials, or media, by the transcriptionof design information, as shown in Figure 1. In the case of concrete material,
these media include Portland cement, water, aggregates, and admixtures.
Concrete infrastructure is more complicated, therefore a greater amount of150

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

media is necessary for its creation; however, some examples include
concrete material, steel reinforcement, and formwork.
Information
Design Information

Knowledge
Transcription

Media

Artifact

Figure 1: Artifact design process (Yoshida and Yashiro, 2007)
Design codes and specifications, such as mixture proportions andmixing procedures, make up the design information necessary to form
concrete material artifacts. These design information are the accumulationof years of experimental work as well as field experience, and are theproduct of negotiation between actors in the concrete field as to theappropriate form of the concrete artifact being developed. When the final
design information is agreed upon by the participating actors, then it
becomes the governing design code to be utilized by concrete engineers in
the field.
3.2 Sustainability
Sustainability was originally defined by the Brundtland Commission
in a report for the United Nations on sustainable development and its
political implications. In this report, sustainable development was describedas practices which meet the needs of the present without compromising theneeds of future generations to meet their needs (United Nations, 1987). This
report established the precedent for sustainable development.
The American Society of Civil Engineers (ASCE) adopted anengineering-focused definition of sustainability in 1996, which stated thatsustainable development should meet human needs while considering theenvironment and natural resources necessary for the future. Furthermore, theASCE Code of Ethics was revised to contain language requiring engineers
to follow sustainable practices (ASCE, 2006).
As mentioned earlier, population growth and urbanization are driving
an increase in the need for concrete to construct the infrastructure necessary
to meet society’s needs. Therefore the concrete industry is facing two
opposing problems; it must meet increasing demand while reducing theindustry’s environmental impact and resource consumption. The American

Utilizing Heterogeneous Engineering in Concrete Material Innovations for Sustainable Development151

July 2008, Thailand

Concrete Institute (ACI) and the Portland Cement Association (PCA)
organized the Concrete Summit on Sustainable Development in March 2007
in order to discuss these problems as well as develop a plan of action for theconcrete industry. At this summit, opportunities for sustainable development
were identified as energy consumption, generation of greenhouse gases,
land use, resource consumption, dust and diesel emissions, andreduce/reuse/recycle applications. The committee understood that, while
there are many areas in which concrete is not meeting sustainable practices,
there are aspects of concrete construction which should be enhanced toincrease the competitiveness of concrete as a construction material: fire andforce protection, thermal mass, and durability (Bédard and Sordyl, 2007). A
sustainable development framework was constructed to encompass andillustrate these discussions (Figure 2).
Employment & shareholder equity
Economic
Public policies &management practices
Governance
Environmental

Resources &ecosystem

SocialQuality of life, health,& social equity

Figure 2: Sustainable development framework (Bédard and Sordyl, 2007)
As shown in Figure 2, the framework for building sustainable
development in the concrete industry necessarily includes non-traditional
engineering fields. In order to successfully implement this philosophy,
concrete engineers must become heterogeneous engineers, reaching outside
their traditional engineering field to mobilize the resources of other fields, tocreate networks which include not only engineers but citizens andgovernment officials, sociologists and economists, researchers and industry
professionals alike.
3.3 Integrating sustainability concepts
When building design information for the transformation of media
into an artifact, engineers have traditionally included only engineeringknowledge and information. However, as discussed in the previous section,
concrete engineers should consider the integration of other fields’
knowledge in order to enhance the development of innovations to meet theneeds of sustainability, as illustrated in Figure 3.

152

Joint Student Seminar on Civil Infrastructures

ICUS Report 30
Traditional
Engineering
Design Information

Economics
Sociology
Environmental
Sustainability

Figure 3: Integrating sustainable concepts into design information
Integrating the knowledge from other fields will necessarily require
their input in the formation of design information. Concrete engineers willneed to include these non-engineer participants as actors in concrete
construction. By including the needs of these new participants, aspects of
the artifact will change as the design information changes to reflect new
knowledge and information. In some cases, the artifact itself may change; insome cases, the process for transforming media may change; finally, it’salso possible that the form and process remain the same but the costdecreases. A combination of these is also possible.

4. CONCLUSIONSThe concrete industry faces change as sustainable development is adopted
into the very ethics which civil engineers must practice by. This will
necessarily result in the development of new innovations to meet thesechallenges while maintaining concrete as a competitive construction
material. In order to promote sustainable practices, ACI proposed aframework whereby the considerations of other fields should be integrated
into the concrete industry. This integration will require adding new actors to
the networks which produce concrete technology.
The sociology of technology has proposed that heterogeneous
engineering is necessary for successful technological innovation. By
negotiating the development of technology amongst actors representing
different technological perspectives, new artifacts may be formed based
upon the needs of those participants. Sustainable concrete practices must,
therefore, consider heterogeneous engineering as a means for integrating
those actors from other fields.

REFERENCES
American Society of Civil Engineers, 2006. Code of Ethics. Retrieved 2008
June 5. http://www.asce.org/inside/codeofethics.cfm
Bédard, C., and Sordyl, D., 2007. Concrete summit on sustainable
development. ACI International July, 54-58.

Utilizing Heterogeneous Engineering in Concrete Material Innovations for Sustainable Development

153

July 2008, Thailand

Latour, B., 2005. Reassembling the Social, Oxford Press.
Law, J., 1987. Technology and heterogeneous engineering. The Social
Construction of Technological Systems, MIT Press.
MacKenzie, D., 1987. Missile accuracy: a case study in the social pressuresof technological change. The Social Construction of Technological
Systems, MIT Press.
Pinch, T., and Bijker, W., 1987. The social construction of facts andartifacts. The Social Construction of Technological Systems, MIT
Press.
United Nations, 1987. Report of the world commission on environment anddevelopment. General Assembly Resolution 42/187, December.
Yoshida, S., and Yashiro, T., 2007. Study of the basic logic of diffusion
using specific models. PICMET’07 conference proceedings, Portland,
Oregon, USA.

154

Joint Student Seminar on Civil Infrastructures

A SIMPLIFIED 3D NUMERICALSIMULATION FORBANGKOK MRT SUBWAY TUNNEL
TRAN VIET DUNG and KYUNHG-HO PARK
School of Engineering and Technology
Asian Institute of Technology, Thailand
vietdungtran82@gmail.com
ABSTRACTThis study deals with the evaluation of measured longitudinal surface
settlements obtained from the Blue Line subway project and thecorresponding 3D numerical simulation for a single tunnel. The simplified
numerical procedure, proposed by Mroueh and Shahrour (2008), is adaptedwith two main parameters: the partial stress release factor αdec and thelength of unlined zone Ldec. The effect of these parameters on thelongitudinal surface settlements is investigated.

1. INTRODUCTION
Bangkok crams more than 10 million people into a rapidly growing area.
Anyone, travelling through the city, braces for an ordeal of wasting hours in
impenetrable traffic. Concern about Bangkok’s increasing heavy traffic led
to the implementation of the first phase of the Bangkok Blue Line Subway
project which was completed and opened in 2004 (Figure 1). In this project,
the tunneling construction was done mostly in soft ground, using EPB(Earth pressure balance) shield.
Numerical simulation of the tunneling requires complex aspects, suchas the soil excavation, the overcut or annular space between the jacking pipe
and the excavation, the application of the pressure, the install of definitive
support constituted of lining rings and the grouting of annular space, nonlinear behaviour of the soil and the lining, and the soil-structure interaction.
In particular, in order to take into account of the boundary condition during
the construction process (for example, overcut, injection of the annular void,
installation of the definite tunnel support), two approaches have been used
(Cheng et al., 2008): the forced controlled approach and the displacement
controlled approach.
The displacement controlled approach simulates tunnelling byapplying displacements to nodes around the tunnel (Sagaseta, 1987;
Loganathan and Poulos, 1998; Park, 2004, 2005; Cheng et al., 2008), while
the force controlled approach simulates tunnelling by removing nodal forces
corresponding to the initial soil stress state. The forced controlled method
predicts wider surface settlement trough accompanied with higher far field155

July 2008, Thailand

settlement than field or centrifuge test data (Simpson et al., 1979; Dasari,
1996: Leca, 1996: Stallebrass et al., 1996). Recently Mroueh and Shahrour(2008) proposed a simplified modelling technique by applying theconvergence-confinement concept to 3D numerical simulation.

Figure 1: Route of the Bangkok MRT Blue Line ProjectThis study deals with the evaluation of measured longitudinal surface
settlements obtained from the Blue Line subway project and thecorresponding 3D numerical simulation for a single tunnel. The simplified
3D numerical procedure, proposed by Mroueh and Sharouh (2008), is
adapted. In this model, there are two main parameters: the partial stressrelease αdec and the length of unlined zone Ldec. The effect of thoseparameters on the surface settlements is investigated.

156

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

2. EVALUATION OF THE MEASURED SURFACE SETTLEMENTDATAAll of the measured surface settlement data are collected for the Zone 23,
from Thiam Ruam Mit to Pracharar Bumphen. The location and groundconditions are shown in Figures 2 and 3, respectively. Three different typesof surface settlement makers were installed approximately at 50 m interval
along the tunnel alignment. The primary object of the measurements withsettlement makers is to measure the maximum surface settlements above thecentreline. In addition, the reading was taken over time covering a period
before shield approaching and after shield passing. The surface settlement
data of total 25 points are collected. Among those, the data of only 11 points
are selected for the further study to avoid the possible measurement error
from other points.

Figure 2: Location of ground settlement makers

A Simplified 3D Numerical Simulation for Bangkok MRT Subway Tunnel

157

July 2008, Thailand

Figure 3: Typical soil profile for Zone 23
Figure 4 and Figure 5 show the summary of the surface settlement
measurements by Type 2 and Type 3, respectively. From Figures 4 and 5, it
can be seen that the maximum surface settlement varied from 14 mm to 33
mm. The longitudinal surface settlement mostly occurred between 40 m (≈7D) to – 40 m (≈ 7D) and can be divided into three zones: Zone 1, about 30
m distance, the ground begins to deform but the shield not reached; Zone 2,
about 15 m distance, starts from the distance in front of the shied face anddevelops significantly during the shield passing; Zone 3 begins after the
performance of the tail void grouting. The surface settlement at the tunnel
face (wa), wa = 4 ~ 16 mm, the surface settlement induced in the unlined
zone (wb), wb= 2 ~ 6 mm and the surface settlement due to complete
released stress of the confinement (wc), wc = 8 ~ 22 mm.

158

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

50

Surface settlement (mm)

-5
-10
-15
-20
23-G2-013
23-G2-015
23-G2-043
23-G2-045
23-G2-047
23-G2-051

-25
-30
-35
-40
50

40

30

20

10
0
-10
Shield position (m)

-20

-30

-40

-50

-40

-50

Figure 4: Measured surface settlement (Type 2)
50

Surface settlement (mm)

-5
-10
-15
-20
-25
-30

23-G3-021
23-G3-023
23-G3-027
23-G3-031
23-G2-035

-35
-40
-45
50

40

30

20

10
0
-10
Shield position (m)

-20

-30

Figure 5: Measured surface settlement (Type 3)

A Simplified 3D Numerical Simulation for Bangkok MRT Subway Tunnel

159

July 2008, Thailand

3. 3D NUMERICAL SIMULATION
Numerical simulation has been conducted using the commercial finite
different code FLAC3D. Figure 6 shows the modelling mesh with 44800
zones and 49245 grid-points, assuming symmetric loading conditions. The
left right boundaries are hinged to prevent the movement in horizontal
direction but are free to allow vertical direction. The width of the left
through the right boundaries is set to prevent boundaries effect on theperimeter of the tunnel. At the bottom, the boundary is fixed against verticalmovement. Although, using EPB shield, the face pressure is varied anddependent on the ground condition, the average value of 150 kN/m2 is usedin this study.

Figure 6: Modelling mesh
The constitute law used for the soil element is the elasto-plastic
associated Mohr-Coulomb model. The material parameters of soil and lining
are given in Figure 3.
Excavation and the shield advance are simulated through the step bystep procedure as follows:
In the first step of excavation, (a) remove the ring of soil element
equal to 7 m ahead of the shield (6m for length of the shield and the lengthof the unlined zone and 1 m for the supported zone where the lining will be
installed), (b) release stress around the tunnel, (c) grout the removed area,(d) install lining 1 m at the end of the excavated and measure thedisplacement at the tunnel boundary and at the surface, (e) back fill material
and apply face pressure to prepare for the next excavation.
In the step of tunnel face advance, (a) remove the ring of soil element
ahead of the tunnel face, (b) release the stress using αdec and Ldec, (c) grout
the removed area, (d) activate the lining element in removed are with the160

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

length of Llin and take the measurement for the element displacement, (e)apply the pressure at the tunnel face. Then repeat from (a) to (e).

4. RESULTS
4.1 Influence of αdec
The parameter αdec stands for the stress release before the lining
installation. Figure 7 shows the numerical results of the longitudinal surface
settlement using αdec = 0.2, 0.5 and 0.7, together with the measured one. Ldec
= 6 m is used. It shows that the parameter αdec highly affects the maximum
surface settlement. As αdec increases, the maximum surface settlement
increases. The measured surface settlements can be ranged within αdec = 0.2~ 0.7.
50

Surface settlement (mm)

-5
-10
-15
-20
-25
-30

Type 2Type 3alpha 0.2
alpha 0.5alpha 0.7

-35
-40
-45

50

40

30

20
10
0
-10
-20
Distance along tunnel axis (m)

-30

-40

-50

Figure 7: Effect of αdec (longitudinal direction)
4.2 Influence of Ldec
The parameter Ldec stands for the length of the unlined area of thetunnel. Figure 8 shows the numerical results of longitudinal surface
settlements using Ldec = 6 m and 10 m, together with the measured one. αdec
= 0.2 is used. It shows that the parameter Ldec affects slightly. As Ldec
increases, the maximum surface settlement slightly increases. As suggested
by Mroueh and Sharour (2008), the parameter can be fixed to Ldec = 1D.

A Simplified 3D Numerical Simulation for Bangkok MRT Subway Tunnel

161

July 2008, Thailand

50Surface settlement (mm)

-5
-10
-15
-20
-25
-30
Type 2Type 3
L =6 m
L =10 m

-35
-40
-45
50

40

30

20
10
0
-10
-20
Distance along tunnel axis (m)

-30

-40

-50

Figure 8: Effect of Lde

5. CONCLUSION
Measured longitudinal surface settlements, obtained from the Blue Linesubway project, have been evaluated and the corresponding 3D numericalsimulation for a single tunnel has been performed. The effect of the model
parameters was investigated. The following conclusions can be drawn:
1. The maximum surface settlements varied from 14 mm to 33 mm:
wa = 4 ~ 16 mm, wb= 2 ~ 6 mm and wc = 8 ~ 22 mm.
2. The longitudinal surface settlement mostly occurred between 40 m(≈ 7D) to – 40 m (≈ 7D) and can be divided into three zones
3. The parameter αdec highly affects the maximum surface settlement.
As αdec increases, the maximum surface settlement increases. The
measured surface settlements can be ranged within αdec = 0.2 ~ 0.7.
4. The parameter Ldec affects slightly, the parameter can be fixed to
Ldec = 1D.

REFERENCES
Cheng, C.Y., Dasari, G.R., Chow, Y.K., Lueng, C.F., 2008. Finite element
analysis of tunnel-soil-pile interaction using displacement controlledmodel. Tunnelling and Underground Space Technology, 22, 450-466.
Dasari, G.R., Rawlings, C.G., Bolton, M.D., 1996. Numerical modeling of a
NATM tunnel construction in London Clay. Proceedings of162

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

International Symposium on Geotechnical Aspects of UndergroundConstruction in Soft Ground, Balkema, London, 491–496.
3D
Flac Fast Lagrangian analysis of continua in 3 Dimension version 2.0,
1997.
Leca, E., 1996. Modelling and prediction for bored tunnels. Proceedings ofInternational Symposium on Geotechnical Aspects of UndergroundConstruction in Soft Ground, Balkema, London, 27–42.
Longanathan, N., Poulos, H.G., 1998. Analitical prediction for tunneling
induced ground movement in clay. Journal of Geotechnical andGeoenviromental Engineering, 124(9), 846-856.
Mroueh, H., Shahrour, I., 2008. A simplified 3D model for tunnel
construction using tunnel boring machine. Tunnelling andUnderground Space Technology, 23, 38-45.
Park, K.H., 2005. Analytical solution for tunnelling-induced groundmovement in clays. Tunnelling and Underground Space Technology,
20(3), 249-261.
Park, K.H., 2004. Elastic solution for tunnelling-induced ground movement
in clays. International Journal of Geomechanics ASCE, 4(4), 310-318.
Sagaseta, C., 1987. Analytical of undrained soil deformations due to groundloss. Geotechnique, 37(3), 301-320.
Simpson, N.J., O’Riordon, Croft, D.D., 1979. A computer model for the
analysis of ground movements in London clay. Geotechnique, 29(2),149–175.
Stallebrass, S.E., Grant, R.J., Taylor, R.N., 1996. A finite element study ofground movements measured in centrifuge model tests of tunnels.
Proceedings of International Symposium on Geotechnical Aspects ofUnderground Construction in Soft Ground, Balkema, London, 595–
600.

A Simplified 3D Numerical Simulation for Bangkok MRT Subway Tunnel

163

July 2008, Thailand

164

Joint Student Seminar on Civil Infrastructures

SEISMIC BEHAVIOR OF PRECASTHYBRID MOMENT RESISTING FRAMESEKKACHAI YOOPRASERTCHAI,PENNUNG WARNITCHAI and MATRIN SUTHASIT
School of Engineering and Technology
Asian Institute of Technology, Thailand
st106327@ait.ac.th
pennung@ait.ac.th
st106326@ait.ac.th
ABSTRACT
It is the first challenge to introduce the construction of an innovative
structural system, Precast Hybrid Moment Resisting Frames (PHMRF), in
Thailand. Under a project initiated by National Housing Authority ofThailand (NHA), a relatively large amount of typical 5-story residentialbuildings will be constructed in the moderate seismic risk zone. Because of
the requirements for rapid construction of low-cost, seismic resistant, midrise residential buildings, PHMRF was chosen as the structural system. This
structural system is consisted of precast concrete beam and precast
concrete column assembled together using a combination of post-tensioning
tendons and mild steels.
To comprehensive understand the behavior of hybrid systems, two 2/3scale model interior and exterior beam-column joints representing the 5story residential buildings were tested under quasi-static reversed cyclicloads. The capacity design concept was used to design the hybrid
connections as well as the precast members to limit the inelastic behavior in
the beam to column interfaces. Test results demonstrate that the hybrid
connections can dissipate a lot of energy with low or zero strength
degradation up to story drift of 6.00%. In addition, the specimens
demonstrated the self-centering behavior. The damage was limited to thegrout interface. Only minor cracks could be observed in the beams andcolumns.

1. INTRODUCTION
The boom of the use of precast concrete structures in many countries
requires innovative deliberation since many regions are located in theseismic hazard areas. There are many evidences demonstrated that the
precast concrete buildings are vulnerable to the effects of earthquake
loading, especially in the connections. Consequently, the challenge is to
discover economical and practical ways to assemble the precast elements
together to have sufficient strength and ductility. Normally, precast
concrete seismic structures can be divided into two systems. The firstsystem is emulation of monolithic reinforced concrete construction. Another165

July 2008, Thailand

system is jointed precast. In the first approach, typically referred to as“emulation” of cast in place concrete, precast elements are jointed by using
wet connection. Many solutions have been studied and developed for beamcolumn connections. The connection can either be located within the beamcolumn joint or in the middle of a structural member. In this approach, thejoint must have adequate strength and stiffness as the cast in place concrete.
To achieve this target, the joint planes and the protruding bars must be
detailed in proper ways. The reinforcing bars between the precast concreteelements may be connected together by using the mechanical couplers or
grout ducts and filled later by cast in place concrete or pressure grout.
This paper studies the seismic performance of jointed precast concrete
moment resisting frames by experimental program. The beams illustrated
here rock about their columns and self-center upon unloading whichdeveloped by Priestley and Tao (1993) and Stone et al. (1995) as a part of
the PREcast Seismic Structural Systems (PRESSS) Research Program.
These beams and columns are assembled to form moment resisting frames
by using the combination of unbonded post-tensioning tendons to provide
flexural strength and self-centering with mild steel for inelastic energy
dissipation. The plane of significantly reduced stiffness and strength would
be limited at the interface between adjacent precast concrete elements.

2. DESCRIPTION OF PRECAST HYBRID BEAM-COLUMNCONNECTIONSThe unbonded post-tensioning tendons are placed at the center of the beams
where the elastic strain in the tendons minimize, thus, the self-centering canbe achieved. In order to get the maximum energy dissipation, mild steels
are placed near the top and bottom of the beams. However, the maximum
nonlinear strains in the bars would be concentrated on the interface between
precast concrete beams and columns when the gaps are opened. This effectmake the bars fracture in the seismic event. To delay bar fracturing during
the deformations of the bars in tension, bond between the mild steels and thegrout cement should be prevent over a predetermined length at the ends ofthe beams by wrapping the bars with flexible ducts. In addition, highcompressive stress occurs in the opposite side. Presence of steel angle at thebeam corners could confine and prevent the spalling of the concrete in thiszone (Figure 1).

3. DESCRIPTION OF PROTOTYPE BUILDINGSThe 5-story residential building was designed to resist possible
earthquake loads in Thailand. The typical span and story height are 3000
mm and 2800 mm respectively. Seismic zone 2A according to UBC1997
comparable to required seismic zone in North of Thailand was selected asseismic loading in elastic 2-D model. The computer model was constructed
and analyzed by using SAP2000 program. The capacity design concept wasused to design beam and column sections. The inelastic zone would be

166

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

expected to limit at the interface between beam and column. The design
procedure is out of scope of this paper. The design detailing of thebuildings is described elsewhere in Warnitchai et al. (2008). Since the floor
span in longitudinal direction of the building has uniform length, the interior
and exterior beam-column joints at the second floor were selected toconstruct the physical model and test in laboratory.
Non-shrink grout cement with fiber
Steel angle
Unbonded material

Unbondedprestressing
tendonMild Steel

Figure 1: Configuration of precast hybrid beam-column connection

4. EXPERIMENTAL PROGRAM
The seismic performance of precast hybrid beam-column connection
was carried out through the experiment. The two-third scaled subassemblage elements were constructed and tested in the laboratory underquasi-static cyclic loading test. Both interior and exterior hybrid joints were
investigated.
4.1 Test specimens
4.1.1 Interior beam-column connection specimen
The typical dimension and reinforcing bar details of precast beam andprecast column are shown in Figure 2. Beam section is 170×270 mm andcolumn section is 320×320 mm. Circular corrugated ducts of 25 mm
diameter were preformed on the required positions at beam and column.
Two deform bars of 10 mm diameter were used to pass through between
beam and column. The unbonded length of 60 mm was applied on theinserted bars at the beam surface. Two post-tensioning strands with 12.7mm diameter were inserted passing two PVC ducts placed at the center ofbeams. PVC ducts were not grout in order to simulate the unbonded
situation. The stressing force after losses was approximately 0.45fpu where
fpu is ultimate stress of the tendon. Axial force in column, approximately
0.10fc’Ag where fc’ is ultimate compressive strength in the column and Ag isthe total cross section area, was simulated by using two 15.4 mm posttensioning tendons. Steel angles, 75 mm width, 75 mm depth, 6 mm
thickness, were provided at beam faces to confine the concrete at the beam
ends. It could prevent the crushing and spalling of concrete at precast beams,

Seismic Behavior of Precast Hybrid Moment Resisting Frames167

July 2008, Thailand

since high compressive stress occurs in this area. The fiber grout cement
was poured in the beam-column interfaces to make the integrity of thestructures. The fibers are benefit to reduce the spalling of the grout pad.

Figure 2: Detailing of the test specimens.
4.1.2 Exterior beam-column joint specimen
Exterior beam-column subassemblage was tested in order to deeply
understand seismic behavior and performance of the hybrid connection. In
addition, it was to ensure that the hybrid connection can maintain seismic
performance and behavior even in exterior joint. This specimen has thedetails and dimensions of precast beams and column as same as interior
beam-column joint specimen, except for only one precast beam installed.
Besides, the anchorages were embedded in the beam-column joint tosimulate the actual construction. In general, the anchorage must be provided
at the exterior joint to grip the post-tensioning steels. Moreover, to preventthe bursting cracking in the column during stressing the post-tensioning
tendons, the spiral transverse reinforcement bars were applied in the column
to confine the concrete in that region.

168

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

4.2 Experimental setup
All specimens were tested under quasi-static loading. Lateral load
was applied at the top of the precast concrete column by a MTS servohydraulic actuator with capacity of ±500 kN. Figure 3 and Figure 4 show
the schematic of the experimental setup for interior and exterior beamcolumn connection respectively. The bottom support of the precast concrete
column is hinge connection, and the top of precast concrete columns isdesigned to move freely. The beam supports is designed to be the roller
connection to force the precast concrete beam moving in horizontal
direction only.
Hence, the inflection point of the beam-column
subassemblies could be achieved in this test setup.
Support Frame+/- 50 Ton MTS Actuator

2-0.6" PC strands

Reaction wall
Hinge

Hinge

Figure 3: Experimental setup for interior joint.
Support Frame+/- 500 kN MTS Actuator

2-0.6" PC strands

Reaction wall
Hinge

Hinge

Figure 4: Experimental setup for exterior joint.
4.3 Instrumentation
The instrumentation consisted of 1) horizontal force measurement andhorizontal displacement, 2) flexural rotation in beam and column, 3) shear
deformation in beam, column and joint, 4) gap at the interface between joint
face and beam and 5) strains of inserted mild steel.
4.4 Loading history
The load applied slowly to the specimen was lateral cyclic
displacement-controlled. The column was pushed and pulled with gradually
increasing story drifts of ±0.25%, ±0.50%, …, and ±6.00% as shown inSeismic Behavior of Precast Hybrid Moment Resisting Frames

169

July 2008, Thailand

Figure 5. At each drift level, the displacement was repeated three times tocheck the degradation of strength and stiffness as well as to examine theenergy dissipation.

Figure 5: Cyclic loading history.

5. EXPERIMENTAL RESULTS
The hysteretic loops of both specimens were plotted in range of story drift
from 0.25% to 6.00% as shown in Figure 6 and Figure 7, respectively.
Based on experimental results, they showed good stiffness in elastic range,
and low stiffness degradation in high story drift levels. The hysteretic loops
also showed the stable behavior of measured peak lateral forces. The
measured peak lateral forces considerably increased in range of story drift
0.25% to 1.50%. After that, the peak lateral force slightly increased fromthe 1.50% story drift level to the 6.00% story drift. Low-level degradationof the peak lateral forces was observed. At the end of the test, as expected,
the test specimen demonstrated that primary deformation and severe damage
took place at the grout pad between beam-column interfaces. There were
only small cracks observed. These cracks were invisible upon unloading
due to axial forces contributed by unbonded post-tensioning tendons. The
beam-column interfaces also experienced large opening at the high story
drift levels. However, when the frame returned to the initial position or zerostory drift level, the gaps were returned to the original condition. The
various key parameters are concluded in Table 1.

170

Joint Student Seminar on Civil Infrastructures

ICUS Report 30
Lateral Load (kN)80

Maximum Lateral Load = 72.55 kN
60

40

20

0

-20

-40

-60

Maximum Lateral Load = 64.51 kN
7.00

6.00

5.00

4.00

3.00

2.00

1.00

0.00

-1.00

-2.00

-3.00

-4.00

-5.00

-6.00

-7.00

-80

Story Drift(%)

Figure 6: Hysteretic responses of interior joint.
Lateral Load (kN)60

Maximum Lateral Load = 38.51 kN
40

20

0

-20

Maximum Lateral Load = 30.82 kN

-40

8.00

7.00

6.00

5.00

4.00

3.00

2.00

1.00

0.00

-1.00

-2.00

-3.00

-4.00

-5.00

-6.00

-7.00

-8.00

-60

Story Drift(%)

Figure 7: Hysteretic responses of exterior joint.

Table 1: Test results of key parameter at various story drifts.
Description
Elastic
Yielding of special
reinforcement
Elastic Stiffness
Maximum strength(push direction)
Maximum strength (pulldirection)
Strength ratio between
3rd cycle and 1st cycle atdrift of 3.50%
Energy dissipation ratio
at drift of 3.50%

Interior beam-column
joint±0.75%±1.50%

Exterior beamcolumn joint±0.75%±1.00%

4,975 kN/m
72.55 kN (+4.50%)

2,335 kN/m
38.51 kN (+6.00%)

64.51 kN (-4.50%)

30.82 kN (-6.00%)

0.93

0.96

0.236

0.254

Seismic Behavior of Precast Hybrid Moment Resisting Frames

171

July 2008, Thailand

6. CONCLUSION
In this study, the precast concrete ductile joints are reviewed. The
experiment was conducted to get comprehensive understanding of the
precast hybrid frames. The two 2/3-scale model precast hybrid beamcolumn connections were tested under the quasi-static cyclic loading test.
Based on the test results, the following conclusion and observation can be
made.
1. The post-tensioning tendons were used to connect the precast
members and mild steel used as energy dissipators. The tendons provide not
only the cramping forces to resist the vertical load at beam-column
interfaces, also the self-centering force to bring the structure back to theoriginal position.
2. As expected, the short unbonded length between mild steel andconcrete can prevent fracturing and reduce cracking of the concrete.
3. The hybrid system can be designed to have the same flexuralstrength as a cast in place concrete system with members of the same size.
4. The specimens have shown a very large drift capacity. Both canbe tested up to the story drift of ±6.00% with slightly damage observed.
The strength degradation of the specimens is also very low.
5. Most of the damage was limited to the beam-column interfaces.
In this area, the inelastic characteristics were provided by the opening of thegaps and yielding of the mild steel.
6. The hybrid connection has been shown to be a superior candidate
for precast concrete frames constructed in seismic hazard zones.

ACKNOWLEDGEMENTS
This research work was funded by the National Housing Authority ofThailand. We wish to express our sincere appreciation to the organization
for providing the opportunity to undertake this research work.

REFERENCES
Priestley, M. J. N., and Tao, J. R., 1993. Seismic Response of Precast
Prestressed Concrete Frames with Partially Debonded Tendons. PCI
Journal, V.38 No.1, January-February, pp. 58-69.
Stone, W., Cheok, G., and Stanton, J., 1995. Performance of Hybrid
Moment-Resisting Precast Beam-Column Concrete Connections
Subjected to Cyclic Loading. ACI Structural Journal, V.91, No. 2,
March-April, pp. 229-249.

172

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Warnitchai, P., Matupayont, S., Pimanmas, A., Yooprasertchai, E. andSuthasit M., 2008. Development of Precast Concrete Frame Buildings
for Seismic Regions. Research Report submitted to NHA of Thailand(in Thai).

Seismic Behavior of Precast Hybrid Moment Resisting Frames

173

July 2008, Thailand

174

Joint Student Seminar on Civil Infrastructures

LABORATORY STIFFNESSMEASUREMENTS ON TOYOURA SANDHIROAKI EBIZUKA1, RUTA IRENG WICAKSONO2
and REIKO KUWANO3
1-2
Department of Civil Engineering, The University of Tokyo, Japan
3
International Centre for Urban Safety Engineering,
Institute of Industrial Science, The University of Tokyo, Japanebizuka@iis.u-tokyo.ac.jp
ruta@iis.u-tokyo.ac.jp
kuwano@iis.u-tokyo.ac.jp

ABSTRACTA triaxial test apparatus combined with two independent wave
measurement methods, i.e. Trigger Accelerometer and Bender Element, wasemployed. A series of tests was conducted to the specimens of Toyoura sand.
Analyses were performed on the test results to obtain statically anddynamically measured moduli. The values of shear modulus resulted fromstatic measurement, Trigger Accelerometer, and Bender Element methods
were compared at different isotropic stress levels. The effects of specimen
size on static and dynamic measurements were studied.

1. INTRODUCTION
In the past, dynamic measurements regarding wave velocity analysis, basedon the cross-hole and down-hole methods, have been used for a long time inreal construction sites (Stokoe & Hoar, 1978). Recently measurement ofwave velocities in the laboratory has also become popular, and researchers
have recognized that “dynamic” and “static” properties are no moredifferent from each other except for the strain levels (Woods, 1991). Precise
static small strain measurements in the laboratory tests have bridged the gapof strain levels between “dynamic” and “static” behavior (Tatsuoka andShibuya, 1992). However, following the pioneer work by Tanaka et al.
(2000), AnhDan and Koseki (2002) found that the difference on dynamic
and static properties is not only caused by strain level but also by someother factors like grain size and wave length.
Among many laboratory tests with dynamic measurements based onelastic wave propagation, this study focused on two independent wave
measurement methods in a series of triaxial tests, i.e. Trigger-Accelerometer(TA) method and Bender Element (BE).

175

July 2008, Thailand

2. MATERIAL, APPARATUS, AND TEST PROCEDURES
Air-dried Toyoura sand (Gs=2.635, emax=0.966, emin=0.600, D50=0.20 mm)
was used as the test material. The material particles were pluviated throughair to prepare cylindrical specimens. As the initial condition, the specimens
were consolidated with a confining stress ( σ c’) of 25 kPa in the airpressured cell. Seven tests of specimens having different dry densities (ρ)
were performed as presented in Table 1.

Test
No.
T1
T2
T3
T4
T5
T6
T7

Table 1: List of the tested specimens
Material
Dry density,
Specimen Size[dia. (cm);ρd3height(cm)](gram/cm )Toyoura sand
1.458
5 ; 10Toyoura sand
1.590
5 ; 10Toyoura sand
1.533
5 ; 10Toyoura sand
1.595
5 ; 10Toyoura sand
1.597
5 ; 10Toyoura sand
1.602
5 ; 10Toyoura sand
1.604
5 ; 10

The triaxial test apparatus was used for this study. To evaluate
dynamic measurement based on elastic wave propagation, two independent
wave measurement methods were employed, i.e. Trigger Accelerometer(TA) and Bender Element (BE). Triggers and accelerometers werecombined to observe the wave propagation through the specimens using P
and S waves (AnhDan et al. 2002). On the other hand, only S wave was
employed during dynamic measurement with BE. Photo and schematic
figure of Trigger Accelerometer (TA) and Bender Element (BE) methods
are presented in Figure 1.
a)b)

Loading
shaft

Transmitter
Bender Element

Top Cap

Trigger

P waveS wavedBE
ReceiverBender Element
PedestaldTAcAccelerometer

Specimen
LDT

Figure 1: Specimen, Trigger Accelerometer, and Bender Element
Starting from a confining stress (σc’) of 25 kPa, the isotropic stresslevels were increased to 50 kPa, 100 kPa, 200 kPa, and 400 kPa. At eachstress level, after a 10 minute stage with constant stress state, 11 cycles ofvertical loading with a single axial strain amplitude of about 0.002%
measured by Local Deformation Transducer, LDT (Figure.1c), were carried

176

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

out as a static measurement of soil stiffness. During the cyclic loading stage,
the vertical stress was unloaded first then reloaded to the original stresslevel under drained condition. After completing the cyclic loading, anotherstage with constant stress state was maintained while conducting the
dynamic measurement using TA and BE methods.

3. PROCEDURES FOR ANALYZING TEST RESULTIn order to evaluate quasi-elastic stiffness modulus based on static
measurement, data of the fifth and the tenth cycles among 11 cyclic loadingwere analyzed. A typical result is shown in Figure 2, where increments ofthe vertical strain and stress were detected with LDTs and the load cell,respectively. The stress-strain relationship was fitted by a straight line andthe quasi elastic vertical Young’s modulus (Es) was evaluated from theslope of the line.

Vertical Stress, σ1 (kPa)

201
200

Toyoura Sand
T4, σ3= 200 kPa

199

ES =

335.8 + 345.1= 340.5MPa
2

198
197

Es

ES, 5th cyclic=335.8 MPa
1

196
195
0.0805

ES,10th cyclic=345.1 MPa
0.08100.08150.08200.0825

Vertical Strain, ε (%)

Figure 2: Analyzing Young’s Modulus resulted from cyclic loading
In the dynamic measurement analysis, a wave velocity (V) was
evaluated using equation (1), as follows:

V =

d
t

(1)

where d is the effective distance between two sensors/transducers asshown in Figure 1b, where dTA and dBE are the effective distance between 2
accelerometers and 2 bender elements, respectively. Meanwhile, t is thetravel time (i.e. the time difference between input and output waves). In thisstudy, input wave is the wave which is captured by upper accelerometer(Figure 1b) or is recorded by transmitter BE. Output wave is the wave
which is captured by lower accelerometer (Figure 1b) or receiver BE.
In wave velocity evaluation, the determination of travel-time plays animportant role, considering the fact that it often depends on subjective
interpretation of each researcher. In this study, to avoid the uncertainties andthe unreliable wave forms while computing wave velocity, the travel-timevalues were evaluated with sinusoidal excitation and rising-to-rising

Laboratory Stiffness Measurements on Toyoura Sand

177

July 2008, Thailand

technique in both the TA and the BE methods. As shown in Figure 3 as a
typical definition used in TA and BE methods, the rising-to-rising travel
time is defined as a distance at time-history-axis from a point obtained after
applying a zero-crossing line at the first input-signal to a point obtained
after applying zero-crossing line at the first output-signal. The zero-crossing
line is applied to correct for the near field effect.

Input/Output Wave (V)

0.12
0.10
0.08
0.06

T1, Toyoura sand
σ1=σ3=50 kPa

output signal

TA, S-wave
Sinusoidal 1.9kHz

input signal

0.04

tRR=0.000265 s

0.02
0.00

-0.02
-0.00020.00000.0002Time (sec)

0.0004

Figure 3: Definition and Evaluation of travel time
By knowing density of the specimen (ρ), the soil stiffness can beobtained. Since Primary (P) and Secondary (S) waves are employed, bothdynamic Young’s modulus (ED) under unconstrained condition and dynamic
shear modulus (GD) can be evaluated using equation (2) and equation (3)respectively, as follows:

E D = ρ ⋅ VP2(2)

G D = ρ ⋅ V S2

(3)

where VP and VS are wave velocities corresponding to P and S waves,respectively.
In addition, to compare the values of moduli resulted from static anddynamic measurements in this study, the dynamic Young’s modulus (ED)and the static Young’s modulus (Es) were converted to the dynamic shear
modulus (GD) and the statically measured shear moduli (Gsta) using equation(4) and equation (5), respectively, under isotropic assumption as follows:
GD =ED
2(1 + ν )(4)

G sta =Es
2(1 + ν )(5)

where ν is Poisson’s ratio. The value of Poisson’s ratio was set as
0.17 (Hoque, 1996) for Toyoura sand.

178

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

4. TESTS RESULTS AND DISCUSSIONS
Figure 4 shows typical graphs of comparison between static and dynamic
moduli of Toyoura sand at different isotropic stress states under dry andsaturated conditions, respectively. Hereafter, the values of shear modulus
under dry and saturated conditions are plotted on the graph with solid andhollow symbols, respectively.
1000
830 b)
665 T5: Toyoura Sand
500
Saturated, e=0.650

330

330

Shear Modulus, G (MPa)1000
830 a)
665 T4: Toyoura Sand
500
Dry, e=0.651

165

TA P wave
TA S wave

100

BE
Static50
50

TA S wave

165

100

100

BE
Static50200

σ1= σ3 (kPa)

300

400

TA P wave

50

100

200

σ1= σ3 (kPa)

300

400

Figure 4: The values of shear moduli on Toyoura sandAs shown in Figure 4a and 4b for under dry and saturated conditions
respectively, the values of dynamic shear modulus with the BE (GD,BE) andthe value of the statically measured shear modulus (Gsta) on Toyoura sandare compared. The values of GD,BE were at largest 20% larger than those of
Gsta. Similar tendency was observed between the specimens under dry andsaturated conditions. Under dry condition, the values of the dynamic shear
modulus with TA method using S wave (GD,TA-S) were 15% - 50% larger
than those of Gsta, while the values of dynamic shear modulus with TA
method using P wave (GD,TA-P) were 20% - 70% larger than those of Gsta.
Under saturated condition, the values of GD,TA-S showed the tendency thatwas similar to those observed under dry condition. On the other hand, thevalues of GD,TA-P were significantly larger than those of Gsta under saturated
condition. The values of GD,BE were larger than those of Gsta, but were
smaller than those of GD,TA-S.
The small strain shear stiffness of Toyoura sand was strongly stresslevel dependent. For the specimen with initial void ratio of 0.65, small strain
shear modulus G is proportional to (p’)0.48 in all the measurements. Thistendency also appeared in a saturated specimen. However, the magnitude ofstiffness obtained from different methods including static and dynamic
measurements were not always the same. Usually, the order of themagnitude was GD,TA-S and GD,TA-P > G BE > GSTA. Noticeably large value of
GD,TA-P seen in Figure 4b is due to the fact that the observed wave was likely
to transmitting through the water rather than soil skeleton in the saturated
specimen.
Possible explanations for the discrepancy of stiffness values obtained
from different methods are;Laboratory Stiffness Measurements on Toyoura Sand179

July 2008, Thailand

1. In the static measurement, the stiffness modulus reflects the overall
cross-sectional property of the specimen. On the other hand, in the dynamic
measurement the wave travels through the shortest path made byinterlocking of bigger particles that resulting into larger stiffness modulus ascompared to those by the static measurement (Maqbool, 2005).
2. The difference between two kinds of dynamic shear moduli
measured with the TA and the BE methods is due possibly to the effects ofbedding error at the interface between the bender element and the specimen
at both the top-end and the bottom-end. Gravelly soil yielded in larger sizeof the locally loose zone at the interface as compared to that with sandy soil
seems to result in longer travel time (i.e. smaller dynamic shear modulus)(Wicaksono, 2007).
The above explanations are more relevant to coarser material.
Wicaksono (2007) conducted similar study on Hime gravel having the mean
diameter of 2mm, and found that the difference of G obtained from static,
BE and TA method were more significant.

5. CONCLUSIONS
1. The small strain shear stiffness of Toyoura sand was strongly stresslevel dependent. Small strain shear modulus G is proportional to (p’)0.48 inall the measurements for both dry and saturated specimen.
2. The values of shear moduli resulted from dynamic measurements
were always larger than those resulted from static measurement, and thevalues of shear moduli obtained from Bender Element method were always
smaller than those from Trigger Accelerometer method.

REFERENCES
AnhDan, L.Q., Koseki, J. and Sato, T., 2002. Comparison of Young’s
Moduli of Dense Sand and Gravel Measured by Dynamic and Static
Methods. Geotechnical Testing Journal, ASTM, Vol. 25 (4), pp. 349368.
Hoque. E., 1996. Elastic Deformation of Sands in Triaxial Tests. PhD.
Thesis, University of Tokyo, Japan.
Maqbool, S., 2005. Effects of Compaction on Strength and Deformation
Properties of Gravel in Triaxial and Plane Strain Compression Tests.
PhD Thesis, Dept. of Civil Engineering, The University of Tokyo,
Japan.
Stokoe, K.H., II and Hoar, R.J., 1978. Field Measurement of Shear Wave
Velocity by Crosshole and Downhole Seismic Methods. Proc. of Conf.
on Dynamic Methods in Soil and Rock Mechanics, Karlsruhe,
Germany, Vol. 3, pp. 115-137.

180

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Tanaka, Y., Kudo, K., Nishi, K., Okamoto, T., Kataoka, T. and Ueshima, T.,
2000. Small Strain Characteristics of Soils in Hualien, Taiwan. Soils
and Foundations, Vol. 40 (3), pp. 111-125.
Tatsuoka, F. and Shibuya, S., 1992. Deformation Character-istics of Soils
and Rocks from Field and Laboratory Tests. Proc. of 9th AsianRegional Conf. of SMFE, Bangkok, Vol. 2, pp. 101-170.
Wicaksono, R.I., Tsutsumi, Y., Sato, T., Koseki, J. Kuwano, R., 2007. Small
Strain Stiffness of Clean Sand and Gravel Based on Dynamic andStatic Measurements. Proc. of 9th IS Symposium, JSCE, pp. 171-174.
Woods, R.D., 1991. Field and Laboratory Determination of Soil Properties
at Low and High Strains. Proc. of 2nd Intl. Conf. on Recent Advancesin Geotechnical Earthquake Eng. and Soil Dynamics, pp. 1727-1741.

Laboratory Stiffness Measurements on Toyoura Sand181

July 2008, Thailand

182

Joint Student Seminar on Civil Infrastructures

WEAKLY-SINGULAR INTEGRALEQUATIONS FOR CRACKS IN 3D LINEARPIEZOELECTRIC FINITE MEDIAWEERAPORN PHONGTINNABOOT
JAROON RUNGAMORNRAT and CHATPAN CHINTANAPAKDEE
Department of Civil Engineering, Faculty of Engineer
Chulalongkorn University
wera371@yahoo.com
Jaroon.R@chula.ac.th
fceccn@eng.chula.ac.th

ABSTRACTThis paper presents the development of a pair of weakly-singular,
weak-form integral equations for cracks in a three-dimensional, linear
piezoelectric finite medium. A systematic regularization technique isestablished based upon the integration by parts via Stokes’ theorem andspecial decompositions of certain singular kernels. The resulting integral
equations contain only weakly singular kernels of order O(1/r) and, as aresult, they allow continuous interpolations to be employed everywhere in
the numerical approximation. This pair of weak-form integral equations
forms a basis for the development of a well-known numerical technique, asymmetric Galerkin boundary element method (SGBEM), well-suited foranalysis of cracks in a piezoelectric finite body.

1. INTRODUCTION
Boundary integral equation methods (BIEMs) are ones of well-known
numerical techniques that have proven efficient for modeling linear
boundary value problems involving a homogeneous domain. An attractive
feature associated with the reduction of one spatial dimension of the key
governing equation and its subsequent discretization renders the methods
superior than the standard finite element method when the volume-surface
ratio of the domain becomes large. Among various types of BIEMs, aweakly-singular, symmetric Galerkin boundary element method has
successfully been used to accurately and efficiently model problems
involving embedded-singularity such as cracks and dislocations in elastic
media (e.g. Xu and Ortiz, 1993; Li et al., 1998; Xu, 2000; Frangi et al.,
2002; Rungamornrat and Mear, 2008b). The key feature of the techniquebesides the symmetric form of the governing weak-form equation (SGBEM)
is that all integrals contain only weakly-singular kernels of order O(1/r).
This crucial feature significantly eases both the interpretation and thenumerical treatment of all involved integrals in comparison with thosecontaining strongly and/or hypersingular kernels (e.g. Gray et al., 1990;
Martha et al., 1992; Martin and Rizzo, 1996; Pan and Yuan, 2000) and, in

183

July 2008, Thailand

addition, allows continuous interpolations be used in the numericalapproximation. To suit such the numerical technique (i.e. SGBEM), it
necessitates a nontrivial regularization technique to derive a complete set of
weakly singular integral equations and this effort has extensively been
investigated within the context of Laplace’s equation, linear elasticity, andelastic fracture analysis (e.g. Rungamornrat and Wheeler, 2006; Bonnet,
1995; Li and Mear, 1998; Rungamornrat and Mear, 2008a). It is noted,
however, that work on the development of the weakly-singular SGBEM totreat cracks in piezoelectric solids is still relatively few.
Most recently, Rungamornrat and Mear (2008c) derived a weaklysingular, weak-form integral equation for the generalized surface traction
for three-dimensional, piezoelectric infinite media and then used thisequation to implement the weakly singular SGBEM to solve various
boundary value problems involving isolated cracks. Nevertheless, theirdevelopment is still restricted to the case of cracks in an infinite medium. In
this investigation, we generalize the work of Rungamornrat and Mear(2008c) to establish a pair of weakly-singular, weak-form integral equations
sufficient for modeling cracks in a piezoelectric finite domain. Such a pairof integral equations can further be employed in the development of the
SGBEM for analysis of cracks in piezoelectric components.

2. BASIC EQUATIONSLet Ω denote a linear, homogeneous, anisotropic, piezoelectric finite
medium and let the elastic displacement and the electric potential at any
point x ∈ Ω be denoted by ui with i ∈ {1, 2, 3} and u4, respectively. Notethat a four-component vector uI with I ∈ {1, 2, 3, 4} is introduced only as amatter of convenience and it is termed as the “generalized displacement”.
From here and what follows, the lower case indices range from 1 to 3; theupper case indices range from 1 to 4; and repeated indices imply thesummation over their range. In a similar fashion, the “generalized stress”,
denoted by σ iJ , is defined such that σ ij is the elastic stress tensor and σ i 4 isthe electric induction vector, and the “generalized surface traction”, denotedby t I , is defined such that t I = σ iJ ni . The latter definition implies thatti = σ ij ni is the surface traction and t4 = σ i 4 ni is the surface electric charge.
For a medium that is free of the body force and body charge, a law ofconservation dictates that

∂σ iJ
=0
∂xi

(1)

For linear piezoelectricity, the generalized stress is related to thegradient of the generalized displacement by

184

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

σ iJ = EiJKm

∂u K
∂xm

(2)

where EiJKm is termed as the generalized moduli of the medium.
Consistent with the definition of both σ iJ and uI, Eijkm represent the elastic
moduli, Ei 4 km = Emk 4i represent the piezoelectric constants, andEi 44 m = Em 44i denote the dielectric permittivities (see also the work of Deeg,
1980).

3. STANDARD INTEGRAL RELATIONSConsider a linear, homogeneous, anisotropic, piezoelectric finite bodycontaining a crack as depicted in Figure 1. While the crack surface consistsof two geometrically coincident surfaces, denoted by Sc+ and Sc− , it issufficient and standard to characterize the crack geometry only by a single
surface Sc+ . The ordinary boundary of the body, denoted by So , can be
decomposed into two surfaces: a surface Su on which the generalized
displacement is prescribed and a (compliment) surface St on which thegeneralized surface traction is prescribed. For convenience, let S = So ∪ Sc+
denote the total boundary of the domain and let ST = St ∪ Sc+ .

St , t oSc+Sc−
S o = S t ∪ Su

Su , u oFigure 1: Schematic of a linear piezoelectric body containing a crack.
By generalizing Somigliana’s identity to the case of piezoelectricity
and then employing the constitutive equation (2), one can obtain the integral
relations for the generalized displacement and for the generalized stress at
any interior point x as (see also Denda and Lua, 1999; Liu and Fan, 2001;
Qin and Noda, 2004)

u P (x) = ∫ U JP (ξ − x)π J (ξ )dS (ξ ) − ∫ SiJP (ξ − x)ni (ξ )υ J (ξ )dS (ξ )
S

(3)

S

Weakly singular Integral Equations for Fractures in 3D Linear Piezoelectric Finite Medium

185

July 2008, Thailand

σ lK (x) = − ∫ SlJK (ξ − x)π J (ξ )dS (ξ ) + ∫ Σ iJlK (ξ − x)ni (ξ )υ J (ξ )dS (ξ )
S

(4)

S

where

⎧t J (ξ );π J (ξ ) = ⎨ +ξ ∈ So(5)−+⎩t J (ξ ) + t J (ξ ); ξ ∈ Sc
ξ ∈ So⎧u J (ξ );υ J (ξ ) = ⎨ +−+⎩u J (ξ ) − u J (ξ ); ξ ∈ Sc

(6)

U JP (ξ − x) and SiJP (ξ − x) are the generalized displacement andgeneralized stress fundamental solutions, and Σ iJlK (ξ − x) is a singular kernel

defined by Σ iJlK (ξ − x) = ElKPq ∂SiJP / ∂ξ q .
Since the kernel SiJP (ξ − x) is singular of O(1/r2) at ξ = x and the kernel

Σ iJlK (ξ − x) is singular of O(1/r3) at ξ = x , the integral equations for thegeneralized displacement and for the generalized surface traction
established directly from (3) and (4) are, therefore, strongly singular andhypersingular, respectively. Evaluation of such integrals is computationallychallenging and, in particular, requires special integral quadratures (e.g.
Gray et al., 1990; Martha et al., 1992; Martin and Rizzo, 1996; Pan and
Yuan, 2000).

4. COMPLETELY REGULARIZED INTEGRAL EQUATIONS

To reduce the strength of singularity of kernels appearing in above two
integral relations (3) and (4), the integration by parts is employed to transfer
the derivative from the kernels to the boundary data. To ease such an
integration by parts process, we introduce the following two special
decompositions, one for the kernel SiJP (ξ − x) and the other for Σ iJlK (ξ − x) :P(ξ − x)∂GmJ
S (ξ − x) = H (ξ − x) + ε ism
∂ξ s
P
iJ

P
iJ

Σ iJlK (ξ − x) = − EiJKlδ (ξ − x) + ε ism∂∂ tK
CmJ (ξ − x)
ε lrt
∂ξ r
∂ξ s

(7)

(8)

P
tK
and CmJ
arewhere H iJP (ξ − x) = −δJP (ξ i − xi ) / 4π r 3 and GmJ
functions that are singular of O(1/r) at ξ = x . A particular solution ofP
tK
GmJ
and CmJcan explicitly be obtained by solving the systems of partial
differential equations (7) and (8) by a method of integral transform (also see
the work of Rungamornrat and Mear, 2008a).

186

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

4.1 Weakly singular integral equation for generalized displacement
A singularity-reduced integral relation for the generalized
displacement can be obtained by substituting the decomposition (7) into theintegral relation (3) and then performing integration by parts via Stokes’
theorem. The resulting integral relation is subsequently employed to form
the displacement integral equation through an appropriate limiting process
and, finally, the weakly singular, weak-form integral equation for thegeneralized displacement is established via the introduction of the test
function ~tP to obtain
1 ~tP (y )u*P (y )dS (y ) = ∫ ~tP (y ) ∫ U JP (ξ − y )π J (ξ )dS (ξ )dS (y )
∫
2S
S
S
~
+ t (y ) G P (ξ − y )D υ (ξ )dS (ξ )dS (y )

∫

∫

P

S

mJ

m J

(9)

S

tP (y ) ∫ H iJP (ξ − y )ni (ξ )υ J (ξ )dS (ξ )dS (y )
− ∫~
S

S

where
y ∈ So⎧u P (y );u*P (y ) = ⎨ +−+⎩u P (y ) + u P (y ); y ∈ Sc

(10)

The resulting weak-form integral equation (9) contains only weaklyP
and H iJP ni .
singular kernels of order O(1/r), i.e. U JP , GmJ
4.2 Weakly singular integral equation for generalized surface traction
To obtain singularity-reduced integral relation for the generalized
stress, we apply the decompositions (7) and (8) to the integral relation (4)and then perform the integration by parts of the result via Stokes’ theorem.
Such integral relation is then used to form an integral equation for thegeneralized surface traction. Finally, the weakly singular, weak-form
integral equation is established by multiplying the integral equation for thesurface traction by a test function υ~K and then performing an additional
integration by parts via Stokes’ theorem. The resulting weak-form integral
equation is given by
−

1 ~
tK
υ K (y )t *K (y )dS (y ) = ∫ Dtυ~K (y ) ∫ CmJ(ξ − y )Dmυ J (ξ )dS (ξ )dS (y )∫2SSS
+ D υ~ (y ) G J (ξ − y )π (ξ )dS (ξ )dS (y )

∫

t

∫

K

(11)

S

S

∫

J

tK

∫

+ υ~ (y ) H J (ξ − y )n (y )π (ξ )dS (ξ )dS (y )
S

K

iK

i

J

S

where

Weakly singular Integral Equations for Fractures in 3D Linear Piezoelectric Finite Medium

187

July 2008, Thailandy ∈ So⎧t K (y );t*K (y ) = ⎨ +−+⎩t K (y ) − t K (y ); y ∈ Sc

(12)

Note that the integral equation (11) contains only weakly singulartK
kernels of order O(1/r), i.e. CmJ, GtKJ and H iKJ ni .

5. SYMMETRIC FORMUALATION
Now, let focus attention to the case that the generalized surface traction is
fully prescribed on the entire crack surface. A system of the governing
integral equations for this particular boundary value problem is obtained asfollow: the weak-form integral equation for the generalized displacement (9)is applied to the surface Su (with ~tP = 0 on ST ) and the weak-form integral
equation for the generalized surface traction (11) is applied to the surface
ST (withυ~P = 0 on Su ). The resulting governing equations are given by~~~
Auu ( t ,t ) + BuT ( t , υ) = R1 ( t )B (t ,~
υ ) + C (~υ ,υ) = R (~
υ)
uT

TT

(13)

2

where the bi-linear integral operators APQ , BPQ and CPQ (with P, Q∈{u, T}) are given by~
APQ (X ,Y ) = ∫ X K (y ) ∫ U JK (ξ − y )YJ (ξ )dS (ξ )dS (y )
SP

(14)

SQ

~
K
(ξ − y )DmYJ (ξ )dS (ξ )dS (y )BPQ (X ,Y ) = ∫ X K (y ) ∫ GmJ
SP

SQ

~
− ∫ X P (y ) ∫ H iJP (ξ − y )ni (ξ )YJ (ξ )dS (ξ )dS (y )
SP

SQ

~
tK
CPQ (X ,Y ) = ∫ Dt X K (y ) ∫ CmJ(ξ − y )DmYJ (ξ )dS (ξ )dS (y )
SP

(15)

(16)

SQ

and the linear integral operators R1 and R2 are given by

188

~ 1
~
~
R1 ( t ) = ∫ ~tP (y )u P (y )dS (y ) − AuT ( t , π ) − Buu ( t ,u )
2 Su

(17)

R2 (~
υ) = −(18)

1 ~
υ K (y )t*K (y )dS (y ) − BTT (π ,~υ ) − CTu (~υ ,u )∫2 ST

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

It is evident that the governing integral equations (13) are in a symmetricform.

6. CONCLUSION
A pair of completely regularized, weak-form integral equations for thegeneralized displacement and the generalized surface traction has been
established to treat cracks in a three-dimensional, piezoelectric finite
medium. The key feature of the developed integral equations is that they
contain only weakly singular kernel of order O(1/r) and this offers boththeoretical and computational advantages. In particular, all integrals exist in
an ordinary sense and continuous interpolations can be employed
everywhere in the numerical approximation.
Such a pair of weak-form integral equations has properly been
employed to form a set of governing integral equations for boundary value
problems involving cracks in piezoelectric finite bodies. The resulting
governing equations are in a symmetric form and essentially weaklysingular, and they constitute a basis for the development of a well-known
numerical technique called a symmetric Galerkin boundary element method(SGBEM).

REFERENCES
Bonnet, M., 1995. Regularized direct and indirect symmetric variational
BIE formulations for three-dimensional elasticity. Engrg. Anal. Bound.
Elem. 15, 93-102.
Deeg, WFJ., 1980. The analysis of dislocation, crack, and inclusion
problems in piezoelectric solids. Ph.D. Dissertation, Standford
University, California.
Denda, M. and Lua, J., 1999. Development of the boundary element methodfor 2D piezoelectricity. Composites: Part B 30, 699-707.
Frangi, A., Novati, G. and Springhetti, R., 2002. 3D fracture analysis by thesymmetric Galerkin BEM. Comput. Mech. 28, 220-232.
Gray, L.J., Martha, L.F. and Ingraffea, A.R., 1990. Hypersingular integrals
in boundary element fracture analysis. Int. J. Numer. Meth. Engrg. 29,
1135-1158.
Li, S. and Mear, M.E., 1998. Singularity-reduced integral equations fordisplacement discontinuities in three-dimensional linear elastic media.
Int. J. Fracture. 93, 87-114.
Li, S., Mear, M.E. and Xiao, L., 1998. Symmetric weak-form integral
equation method for three-dimensional fracture analysis. Comput.
Methods Appl. Mech. Engrg. 151, 435-459.
Liu, Y. and Fan, H., 2001. On the conventional boundary integral
formulation for piezoelectric solids with defects or of thin shapes.
Engrg. Anal. Bound. Elem. 25, 77-91.
Martha, L.F., Gray, L.J. and Ingraffea, A.R., 1992. Three-dimensional
fracture simulation with a single-domain, direct boundary element
Weakly singular Integral Equations for Fractures in 3D Linear Piezoelectric Finite Medium

189

July 2008, Thailand

formulation. Int. J. Numer. Meth. Engrg. 35, 1907-1921.
Martin, P.A. and Rizzo, F.J., 1996. Hypersingular integrals: how smoothmust the density be?. Int. J. Numer. Meth. Engrg. 39, 687-704.
Pan, E. and Yuan, F.G., 2000. Boundary element analysis of threedimensional cracks in anisotropic solids. Int. J. Numer. Meth. Engrg.
48, 211-237.
Qin, T. and Noda, N.A., 2004. Application of hypersingular integral
equation method to a three-dimensional crack in piezoelectricmaterials. JSME Int. J. 47, 173-180.
Rungamornrat, J. and Wheeler, M.F., 2006. Weakly-singular integral
equations for Darcy’s flow in anisotropic porous media. Engrg. Anal.
Bound. Elem. 30, 237-246.
Rungamornrat, J. and Mear, M.E., 2008a. Weakly-singular, weak-form
integral equations for cracks in three-dimensional anisotropic media.
Int. J. Solids Struct. 45, 1283-1301.
Rungamornrat, J. and Mear, M.E., 2008b. A weakly-singular SGBEM for
analysis of cracks in 3D anisotropic media. Comput. Methods Appl.
Mech. Engrg., Article in press.
Rungamornrat, J. and Mear, M.E., 2008c. Analysis of fractures in 3D
piezoelectric media by a weakly singular integral equation method. Int.
J. Fracture, Article in press.
Xu, G. and Ortiz, M., 1993. A variational boundary integral method for the
analysis of 3-D cracks of arbitrary geometry modelled as continuous
distributions of dislocation loops. Int. J. Numer. Meth. Engrg. 36,
3675-3701.
Xu, G., 2000. A variational boundary integral method for the analysis ofthree-dimensional cracks of arbitrary geometry in anisotropic elastic
solids. J. Appl. Mech. 67, 403-408.

190

Joint Student Seminar on Civil Infrastructures

UNDRAINED SHEAR STRENGTH
ESTIMATION OF MARINE CLAY USINGSHEAR WAVE VELOCITY
TAE-MIN OH, ILHAN CHANG and GYE-CHUN CHO
Department of Civil and Environmental Engineering,
Korea Advanced Institute of Science and Technology
ohtaemin@kaist.ac.kr
ilhanchang@kaist.ac.kr
gyechun@kaist.ac.kr

ABSTRACT
Undrained shear strength is a critical property in the evaluation ofground resistance. Generally, undrained shear strength is estimated bya vane shear test in the field and an undrained triaxial test in a laboratory.
However, accurate evaluation of the undrained shear strength is difficult
because of the total depth in the field and because of the difficulty ofproviding reliable continuous monitoring of the whole construction process.
Moreover, after the construction of structures, it is impossible to performin situ measurements such as a vane shear test on the site. To overcome
existing disadvantages, this study attempts to estimate the in situ undrained
shear strength by using the relations between the verified shear wave
velocity, the void ratio, and the undrained shear strength. The Shear wave
velocities of marine clay are measured with different void ratios by meansof consolidation cells with piezoelectric bender element sensors;
furthermore, the results show the correlation between the shear wave
velocity and the void ratio. In addition, laboratory vane tests are performed
with different void ratios to verify the relation between the undrained shear
strength and the void ratio.
A profile of the undrained shear strength can be predicted by means ofcorrelated equations with the in situ profile of shear wave velocity.
A comparison of the real undrained shear strength measured in situ and theestimated undrained shear strength in a laboratory confirms that the resultsof the estimated undrained shear strength have reasonable values andtendencies with depth.

1. INTRODUCTION
Undrained shear strength is an important property in determining groundstabilization, and the monitoring of undrained shear strength requires
a nondestructive method. A shear wave is very simple to measure andanalyze. Furthermore, shear wave velocity can indicate characteristics ofsoil, such as density. Because the shear wave velocity increases as the void
ratio decreases, there is a corresponding increase in material density

191

July 2008, Thailand(Santamarina et al. 2001). It is also well known that, in clay, the undrained
shear strength decreases as the void ratio increases (Bartetzko & Kopf 2006;
Sharmasms & Bora 2002; Lambe et al. 1969). This behavior confirms thatthe void ratio is a critical factor in determining the undrained shear strength
in clay. Previous studies have shown the relation between the shear wave
velocity and the void ratio, and between the void ratio and the undrained
shear strength. Hence, the undrained shear strength appears to be directly
correlated to the shear wave velocity. The shear wave velocity, the void
ratio, and the undrained shear strength are correlated and verified witha consolidation test and a bender element in a laboratory test.

2. THEORETICAL BACKGROUND
2.1 Relation between the shear wave velocity and the void ratio
A shear wave has good applicability in soil because it propagates only
through the soil skeleton, and its velocity depends on the effective stress ofthe soil. The shear wave velocity of particulate materials under a zero lateralstrain loading (with a one-dimensional consolidation) can be expressed interms of the vertical effective stress as follows (Hardin & Richart 1963;
Santamarina, et al. 2001):⎛ σ′ ⎞
Vs = α ⎜⎟⎝ 1kPa ⎠β(1)where Vs is the shear wave velocity, σ′ is the effective stress, and theparameters α (the shear wave velocity at 1 kPa) and β are experimentally
determined. Clays with a higher plasticity index generally have a higher β
exponent and a lower α factor.
The relation between the effective stress and the void ratio can be
expressed as two linear lines based on pre-consolidation stress in the semilog scale. The constant A can be the compression index (Cc) or the swelling
index (Cs) depending on the consolidation state. The effective relation
between stress and the void ratio is expressed as follows:e = A ⋅ ln(σ ' ) + B(2)

where e is the void ratio and A and B are constants. If equation 1 and
2 are combined, the effective stress can be removed and the relation
between the void ratio and the shear wave velocity can be expressed asfollows:
1⎛ V ⎞βe = A ⋅ ln ⎜ s ⎟ + B = k1 ⋅ ln(Vs ) + k2
⎝α ⎠

192

(3)

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

where k1 and k2 are constants. Equation 3 should be applied differently
with a normal consolidation (NC) state and an over-consolidation (OC) state.
2.2 Relationship between void ratio and undrained shear strength
In clay, the relation between the void ratio and the undrained shear
strength is generally linear or linear in a log-log scale (Bartetzko et al. 2007;
Huang et al. 1990; Athy 1930). Using the probability and statistics method,
Bartetzko (2007) confirmed that, in clay, the linear relation between thevoid ratio and the undrained shear strength is almost the same as the linear
relation in the log-log scale. In this study, the void ratio is assumed to becorrelated with the undrained shear strength in a linear tendency as shown in
the following equation:

Su = −c1 ⋅ e + c2

(4)

where Su is the undrained shear strength and c1 and c2 are empiricalconstants.

3. EMPERIMENTAL STUDY
3.1 Specimen preparation
The specimens were prepared by boring from a depth of 0 m to 18 m
in reclaimed ground in the Busan - Jinhae Hawjon region. The tested groundconsists of four layers. A thin-walled sampler (D=74mm) was used to obtain
undisturbed specimens. As shown in Table 1, the representative specimens
were selected at depths of 3 m (clayey silt), 6 m (silty sand), 9 m (clay 1),
13 m (clay 2), and 15 m (clay 3). In the laboratory, the specimens were cut
into 40 mm samples for use in consolidation tests.
Table 1: Specimen properties
Depth [m]0.0~5.4

5.4~8.1

8.1~11.0

11.0~14.0

14.0~17.8

Soil type

Clayey
silt

Silty
sand

Clay 1Clay
Clay 2Clay 3

Water content

0.390

0.313

0.540

0.521

0.534

Initial void ratio

1.034

0.829

1.431

1.381

1.415

Unit weight [t/m3]

1.845

1.931

1.744

1.706

1.623

Liquidity limit [%]

-

-

63.2

73.5

78.6

Plasticity limit [%]

-

-

26.7

29.5

35.5

plasticity index [%]

-

-

36.5

44.0

43.1

Undrained Shear Strength Estimation of Marine Clay Using Shear Wave Velocity

193

July 2008, Thailand

3.2 Experimental setup
The experiment was performed by measuring the shear wave
velocities during the consolidation tests, which were divided into fiveeffective steps for each specimen. The test consisted of a consolidation cellwith two bender elements for the shear wave. The equipment used in theexperiment was a function/arbitrary wave form generator, an oscilloscope,and a Multimeter. After the consolidation tests, the undrained shear
strengths were obtained by means of vane tests.
Bender elements (L=12 mm, W=4 mm, and T=0.6 mm) were used toobtain the shear wave velocities in the laboratory. The bender elements,
which were installed at the center of the top and bottom plate, were coatedwith polyurethane to prevent direct contact with water; water can affectother aspects of the bender element operation through leakage of electric
current from the opposite bender element. In addition, silver paint was used
as a shield on the bender elements to prevent the effect of electromagnetic
cross-talk. During the loading, a wave was generated as a pulse signal(10 kHz, AC 10 V) and sent to the source bender element. The response of
the receiver bender element was recorded. The vertical shear-wave travel
time was measured between the top and bottom bender elements.
The vertical deformation of the specimen was measured with a dial gage.
The vertical shear wave velocity (in meters per second) was calculated by
dividing the specimen height (in meters) by the vertical shear wave traveltime(in seconds). Thus, the shear velocity inside the specimen wasmeasured continuously during the consolidation.

Figure 1: Laboratory test setup

194

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

4. RESULTS
4.1 Results of the correlation for the shear wave velocity and the voidratio
The results of the shear wave velocity and the void ratio show thateach specimen has two linear lines in a semi-log scale at the preconsolidation state shown in equation 3. The results of each specimen are
shown in Figures 2, 3, 4, 5, and 6.

Figure 2: Shear wave velocity-void ratio test result in 3m specimen

Figure 3: Shear wave velocity-void ratio test result in 6m specimen

Undrained Shear Strength Estimation of Marine Clay Using Shear Wave Velocity

195

July 2008, Thailand

Figure 4: Shear wave velocity-void ratio test result in 9m specimen

Figure 5: Shear wave velocity-void ratio test result in 13m specimen

Figure 6: Shear wave velocity-void ratio test result in 15m specimen

196

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

The results of the 6 m specimen show a single linear line, regardlessof the consolidation state, because at a depth of 5.4 m to 8.1 m the specimen
consists of silty sand. On the other hand, the clay specimens show two clear
linear lines, indicating that the consolidation state affects the clayey soil
more than the sandy soil.
4.2 Void ratio-undrained shear strength correlation results
Vane tests are performed four times with void ratios to obtain areliable correlation of the void ratio and the undrained shear strength. The
test results are shown in Figure 7. No data was obtained for the 6 m
specimen because of its silty sand nature.

Figure 7: Undrained shear strength measured by laboratory vane tests

Table 2: Constants in undrained shear strength-void ratio relationship
Depth[m]
c1
c2

3
18.06
36.05

6
-

9
146.5
223.2

13
88.78
146.5

15
73.92
136.1

5. ANALYSIS AND DISCUSSION
As a way of verifying the proposed method‘s capability of estimating
undrained shear strength with shear wave velocity, the in situ undrained
shear strength was compared with the estimated in situ undrained shear
strength. Real data of in situ undrained shear strength were obtained fromthe Korea Institute of Geoscience and Mineral Resources (KIGAM); for thecollection of that data, the institute used a resistivity seismic flat dilatometer(RSDMT). The in situ undrained shear strength values were calculated fromtypical equations suggested by Marchetti (1980) and Kamei and Iwasaki(1995).
Undrained Shear Strength Estimation of Marine Clay Using Shear Wave Velocity

197

July 2008, Thailand

On the basis of laboratory tests for each specimen’s relation andconstant (k1 and k2) between the shear wave velocity and the void ratio, thein situ void ratio profile can be estimated with the aid of the in situ shear
wave velocity profile. The tested clay is normally in a consolidation state.
Hence, the linear line at the NC state should be used to infer the in situ void
ratio. As shown in Figure 8, the results of the in situ void ratio profile areinferred.
The undrained shear strength can be estimated from the combinationof the inferred in situ void ratio profile and equation 4 with the constants(c1 and c2) in Table 2. As a result, the estimated in situ undrained shear
strength has a similar tendency and values as the measured in situ undrained
shear strength data in field (Figure 9).

(a) Shear wave velocity comparison(b) Estimated in-situ void ratio

Figure 8: Estimated in-situ void ratio with in-situ shear wave velocity

198

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Figure 9: Comparison between in-situ undrained shear strength

6. CONCLUSION
The relation of the shear wave velocity and the void ratio was obtained bymeasuring the shear wave velocities with the void ratio. The measurements
were taken with the aid of consolidation cells with bender elements. Vane
tests were used to obtain the relation of the void ratio and the undrained
shear strength. The results show that when the void ratio is used as anintermediary, the undrained shear strength can be directly correlated withshear wave velocity.
As a result of measuring the shear wave velocity under the same
effective stress conditions, the marine clay is determined to be in an NC
state. The whole procedure of estimating the undrained shear strength istherefore performed in the NC state. However, if the real field conditions
are changed from an NC state to an OC state due to the removal of thesurcharge, the estimation of the undrained shear strength should be
performed in the OC state. The estimated undrained shear strength can bechanged to a consolidation state because the consolidation state is very
critical in determining the clay characteristics. The method suggested in thisstudy can reflect either an NC state or an OC state.

Undrained Shear Strength Estimation of Marine Clay Using Shear Wave Velocity

199

July 2008, Thailand

On the basis of clay samples, the estimated undrained shear strengthwith shear wave velocity is compared with the undrained shear strength asmeasured with the resistivity seismic flat dilatometer. The results show thatthe method of estimating the undrained shear strength with shear wave
velocity is very reliable and reasonable. Through this estimation method, theundrained shear strength can be monitored with the shear wave velocity
under different conditions, such as the void ratio or the consolidation state.

REFERENCES
Bartetzko, A. and Kopf, A. J., 2007. The Relationship of Undrained Shear
Strength and Porosity with Depth in Shallow Marine Sediments.
Sedimentary Geology, Vol.196, p.235-249.
Bang, E. S., Sung, N. H., Park, S. G., Kim, J. H., Kim, Y. S., Seo, D. N.,
Kim, D. S., and Lee, S. H., 2008. Development and verification of a
resistivity seismic flat dilatometer testing system for efficient soft soil
site charaterization. Geotechnical and Geophysical Site
Characterization, p.1247-1253.
Blake, W. D. and Gilbert, R. B., 1997. Investigation of Possible Relationshipbetween Undrained Shear Strength and Shear Wave Velocity for
Normally Consolidation Clays. Offshore Technology Conference,
p.411-419.
Chang, I. H. and Cho, G. C., 2007. A Labolartory Procedure to Characterize
Reclained Clay Using Shear Wave. Geotechnical Special Publication
164-Innovative Applications of Geophysics in Civil Engineering,ASCE.
Hardin, B. O. and Richart, F. E., 1963. Elastic Wave Velocities in Granular
Soils. Journal of Soil Mechanics and Foundations, ASCE, Vol.89,
SM1, p.33-65.
Kamei T. and Iwasaki K., 1995. Evaluation of undrained shear strength ofcohesive soils using a Flat Dilatometer. Soils and Foundations, Vol.35,
No.2, p.111-116.
Lambe, T. W. and Whitman, R. V., 1969. Soil Mechanics, John Wiley &Sons, LTD.
Marchetti, S., 1980. In situ tests by flat dilatometer. ASCE Journal of
Geotechnical Engineering Division, Vol.196, GT3, p.299-167.
Santamarina, J. C., Klein, K. A., and Fam, M. A., 2001. Soils and Waves,
John Wiley & Sons, LTD.

200

Joint Student Seminar on Civil Infrastructures

SEISMIC RETROFITTING PROMOTIONMODEL FOR MASONRY HOUSESUSING PP-BAND METHOD AND
MICRO-EARTHQUAKE INSURANCE
1NAOKI SORIMACHI1and KIMIRO MEGURO2
Department of Civil Engineering, The University of Tokyo, Japan
2
International Center for Urban Safety Engineering,
Institute of Industrial Science, The University of Tokyo, Japansorry@risk-mg.iis.u-tokyo.ac.jp

ABSTRACTThis study aims to contribute to reducing earthquake damage indeveloping countries that are mainly caused by the collapse of masonryhouses. A new model was proposed and analyzed to promote seismic
retrofitting by eliminating the retrofitting cost from the government and theresidents. Instead, insurance companies were incorporated to bear the
retrofitting cost. By setting a condition that this model is valid if retrofitting
promotion cost is smaller than the reduced amount of government’s
reconstruction expenses due to retrofitting, the possible compensation for
the residents and the wage for local engineers were estimated to see theeffect of this model quantitatively. The results showed that this model
enables to pay enough compensation for reconstruction to the residents, andto raise the wage of local engineers by retrofitting business. Therefore, theproposed model will give incentive of retrofitting to the government and theresidents.

1. INTRODUCTION
Looking at damage by earthquake disasters in developing countries,
collapse of masonry houses is one of the major causes of casualties.
Therefore, seismic retrofitting of weaker masonry houses is the key toreduce earthquake damage. In order to solve this problem, the author’s
research group has developed PP-band method. PP-band method is a simple,
cheap, easy and local acceptable retrofitting method. However, theretrofitting cost of PP-band method (about $30/house for materials) proved
to be still unaffordable for the very low income people. Our research group
has then proposed a “two-step incentive system” to solve this problem. In
this system, the government will provide retrofitting materials for free andask the residents to retrofit their houses. After checking that the houses wereretrofitted properly, the government will give subsidy to the residents (1stincentive). In addition, the residents who have performed retrofitting will beassured to receive more compensation (for example, twice) by thegovernment than those who have not in case their houses were damaged by
the earthquake in the future (2nd incentive). This system proved to reduce201

July 2008, Thailand

the total damage by the earthquake drastically in case of Iran Bam (2003),
Pakistan Kashmir (2005) and Indonesia Java (2006) earthquakes (Iritani,
Meguro, 2007). At least 85% of the death toll could be saved, and, the total
expenditure by the government could be reduced by 96% in Iran, 81% inPakistan and 76% in Indonesia. However, in this system, the initial
retrofitting cost prepared by the government was the key issue, which thisstudy will focus on.
This study aims to propose and analyze a new model to promote
retrofitting in developing countries by using PP-band method. In this model,
insurance companies will bear retrofitting cost instead of the government or
the residents. A condition that indicates the validity of this model was set,
and, under this condition, possible compensation for the residents andpossible wage for local engineers was estimated to see the effect of themodel quantitatively. Case studies were done in Iran Bam area, Pakistan
Kashmir area and Indonesia Java area. The results showed that this model
enables to pay enough compensation for the residents in case of earthquake
disasters, and, enables to raise the wage of the local engineers by PP-band
retrofitting business. Therefore, this model gives incentive of retrofitting indeveloping countries.

2. MECHANISM OF MODEL
The proposed model gives incentive of promoting seismic retrofitting toboth the government and the residents by eliminating their retrofitting cost.
In this model, the insurance companies will bear the retrofitting cost, and, atthe same time, the retrofitted houses will be insured for free. In addition,
when the houses were damaged by the earthquake in the future, insurancecompanies will promise to pay higher compensation to those who have
performed retrofitting than those who have not. On the other hand, theinsurance companies will receive reinsurance money from the government
when the retrofitted houses were damaged by the earthquake. The
government will pay the reinsurance money in range of the reduced amountof expenditure due to retrofitting in advance. The reinsurance money will
cover the retrofitting cost and the interest because the reconstruction
expenses will be reduced greatly due to retrofitting. Figure 1 shows theexpense share in the proposed model. The advantages of this model are that
1) the damage by the future earthquake can be reduced drastically, 2) the
residents can perform retrofitting and be insured for free, 3) the government
will not have to prepare a huge budget for retrofitting in advance, and 4) the
government will not have to decide the priority of the selection of theretrofitting area because the insurance companies will do that based on theirbusiness viewpoints.

202

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Before earthquake

After earthquake

Government

Total expenses mustbe smaller than that of
non-retrofitting case

Government doesn’t have toprepare a large fund beforehand

Insurance company

Retrofitting cost

Retrofitted

Government

Reinsurance

Earthquake
Occurs!!

Compensation for
non-retrofitted

Insurance company

Insured for free by
insurance company

Non-retrofitted

Insurance

Damagereduction

damagedFigure 1: Expense share in proposed model

3. MODEL EFFECT ANALYSIS METHOD
3.1 Outline of model effect analysis method
In order to analyze the effect of the model, the possible compensation
for the residents and the possible wage for the local engineers, under thecondition that the model is valid, were estimated. In this study, case study
was done in Iran Bam area, Pakistan Kashmir area and Indonesia Java area.
A hypothesis was made that the model is valid under the condition as
follows:(I) < (D)(1)
where (I) is retrofitting promotion cost, and (D) the reduced amount of
housing reconstruction expense.
Figure 2 shows the estimation flow of (I) and (D). (I) and (D) were
estimated from the scenario earthquake damage (building damage andhuman loss), the government’s compensation (for housing reconstruction
and casualties) data of the past earthquake disasters (Iran Bam 2003,
Pakistan Kashmir 2005 and Indonesia Java 2006) and the retrofitting cost of
PP-band method.

Seismic Retrofitting Promotion Model for Masonry Houses Using PP-band Method and Micro-Earthquake
Insurance203

July 2008, Thailand

Building data

Estimation of the number of retrofitted
and non-retrofitted buildings
Hazard curve

Scenario
earthquake

Fragility curve

Death rate/house

Estimation of building
damage and human loss
Compensation data of the pastearthquake (Bam, Kashmir, Java)

Retrofitting andreconstruction cost

Estimation of (I)<

Estimation of (D)the condition ofmodel being valid

Figure 2: Estimation flow of (I) and (D)3.2 Earthquake damage estimation
Earthquake damage was estimated by calculating the probability ofbuildings being damaged by the earthquake in the future (P), as follows:(2)+∞

P = ∫ HFds ≅ ∑ H F
−∞

s

s

s

where S is seismic intensity, Hs the probability of earthquake(intensity S) occurring at least once in 50 years, and Fs the fragility ofbuilding against earthquake (intensity S).
Occurrence probability (Hs), as shown in Figure 3, was calculated bymultiplying earthquake occurrence probability of intensity S in 50 years by
the number of times the earthquake occurred. Because of lack of data of thetarget areas, hazard curve of Japan (Japan Seismic Hazard Information
Station, 2008) and earthquake frequency in Japan were substituted for thesetwo. (Hs) was calculated for exceed probability 10 % in 50 years of MMI(Modified Mercalli Intensity) 6.5, 6.7, 6.8, 7.2, 7.5, 7.6, 7.8, 7.9, 8.1, 8.2,
8.4, 8.6, 8.7, 9.0 and 9.7, so as to apply to various areas with different
earthquake potentials. For example, the earthquake potential of Iran Bam
area is MMI 7.33-8.66 of exceed probability 10% in 50 years.

204

Joint Student Seminar on Civil Infrastructures

ICUS Report 30
1000%

9.7
9
8.7
8.6
8.4
8.2
8.1
7.9
7.8
7.6
7.5
7.2
6.8
6.7
6.5

Exceed probability of 10 % in 50 years of MMI 9.7

900%
800%

(Hs)

700%
600%
500%
400%
300%
200%
100%
0%
5

6

6.5

7

8

9

10

11

MMI

Figure 3: Probability of earthquake occurring at least once in 50 years
Fragility of building (Fs), as shown in Figure 4, was estimated bystandard normal distribution formula as follows:s

Fs = ∫ e{−( s′ − μ ) 2
2σ 2

}

−∞

ds ′

(3)

where S is seismic intensity.
(Fs) represents the damage rate of the buildings as a group in certain
area, respect to MMI. Fragility curves as shown in Figure 4 for Iran Bam(collapse), Pakistan Kashmir (collapse and partially damaged), Indonesia
Java (collapse) and PP-band retrofitted (collapse and partially damaged)
were used (JICA, 2000; Iritani et al., 2007).
Iran

100%

Pakistan
100%
90%

collapse

90%
80%
70%
60%
50%

(Fs)

(Fs)

collapse + partially damaged
collapsepartially damaged

80%
70%
60%

40%
30%
20%
10%

50%
40%
30%
20%
10%
0%

0%
1

2

3

4

5

6

7

MMI

8

9

10

11

1

12

2

4

5

6

7

8

MMI

9

10

11

12

PP-band retrofitted

Indonesia
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%

3

100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%

PP-band collapse + partially damaged
PP-band collapse
PP-band partially damaged

(Fs)

(Fs)

collapse

1

2

3

4

5

6

7

MMI

8

9

10

11

12

0

1

2

3

4

5

6

MMI

7

8

9

10 11 12Figure 4: Fragility of building
Seismic Retrofitting Promotion Model for Masonry Houses Using PP-band Method and Micro-Earthquake
Insurance
205

July 2008, Thailand

From the above (Hs) and (Fs), probability of buildings being damagedby the earthquake in the future (P) was calculated as shown in Figure 5.
450%

Iran collapse
Pakistan collapse
Pakistan partially damaged
Indonesia collapse
PP-band collapse
PP-band partially damaged

400%

P=H×F

350%
300%
250%
200%
150%
100%
50%
0%
6.5

7

7.5

8

8.5

9

9.5

10

MMI of exceed probability 10% in 50 years
Figure 5: Probability of buildings being damaged by the earthquake
3.3 Compensation and retrofitting costCompensation for earthquake damage involves reconstruction costand compensation for casualties. Table 1 shows the compensation data usedin this study, obtained from the data of recent earthquake disasters (IranBam 2003, Pakistan Kashmir 2005, Indonesia Java 2006).
Table 1: Compensation for reconstruction and casualties
Compensation Reconstruction [yen] Casualties [yen]Iran218,000
104,000
Pakistan
379,000
180,000
Indonesia
383,000
172,000
Since PP-band method construction can be carried out by the residents,“resident construction” cost and “engineer construction” cost were assumed
for retrofitting cost of PP-band method, as shown in Table 2. Resident
construction cost means material cost, and engineer construction cost meansmaterial + construction cost of PP-band method. Construction costcorresponds to the local engineers’ wage (EERI, World Housing
Encyclopedia, 2007).
Table 2: Retrofitting cost of PP-band method
Retrofitting cost
Iran[yen] Pakistan[yen] Indonesia[yen]Resident construction
7,120
3,370
7,120
Engineer construction
67,18026,77027,440206

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

4. RESULTS AND DISCUSSION
Under the condition that the model is valid, the possible compensation for
the residents (resident construction type) and the possible wages for the
local engineers (engineer construction type) were estimated. Wages for the
local engineers were estimated under the condition that residents will
receive the same amount of money for compensation as reconstruction cost.
Figure 6 shows the results of the case in Iran.
8000

12

7000

wage (specialized)
wage (ordinarily)

10[1,000 yen]

[1,000 yen]

6000
5000
4000
3000

possible compensation
reconstruction cost

2000

8
6
4
2

1000

0

0
6.5

7
7.5
8
8.5
9
MMI of exceed probability 10% in 50 years

9.5

6.5

7
7.5
8
8.5
9
MMI of exceed probability 10% in 50 years

9.5

Figure 6: Possible compensation (left) and wage (right), IranIn case of Iran, in resident construction type, up to about 7,000,000
yen of compensation was possible for residents, which is enough forreconstruction cost of 218,000 yen (Figure 6, left). In engineer construction
type, with the condition that the earthquake potential is over MMI 8.2 ofexceed probability 10 % in 50 years, even if the residents will receive
enough compensation for reconstruction (= 218,000 yen), the construction
cost of PP-band method (= wages for PP-band engineers) can be raised thanthe ordinarily wages of local engineers (Figure 6, right).

5. CONCLUSION
The results show that this model gives incentive to both the residents andthe local engineers. In this model, the residents can perform retrofitting andcan be insured for free. In addition, the residents can accept enoughcompensation for reconstruction in case if their houses were damaged by theearthquake. For local engineers, raising wages for PP-band method
construction is possible. For the government, they will not have to prepare
retrofitting cost in advance. At the same time, this model will not cause
insurance companies any losses. These are all incentives for promoting
seismic retrofitting in developing countries. Our future aim is to estimate theexpenses in detail by considering indirect damages.

Seismic Retrofitting Promotion Model for Masonry Houses Using PP-band Method and Micro-Earthquake
Insurance
207

July 2008, Thailand

REFERENCES
Earthquake Engineering Research Institute, 2007. World Housing
Encyclopedia.
JICA, 2000. The Study on Seismic Microzoning of the Greater Teheran Area
in the Islamic Republic of Iran.
National Research Institute for Earth Science and Disaster Prevention, 2008.
Japan Seismic Hazard Information Station.
Sathiparan
Navaratnarajah,
Paola
Mayorca,
Nesheli
KouroshNasrollahzadeh and Kimiro Meguro, 2005. Evaluation of retrofitting
masonry structures with polypropylene band meshes by means of
diagonal compression tests, the Proceedings of the JSCE Annual
Meeting.
Satoshi Iritani, Paola Mayorca and Kimiro Meguro, 2008. Proposal of asystem to promote retrofitting of vulnerable masonry houses indeveloping countries, Bulletin of Earthquake Resistant Structure
Research Center No.41, 55-60.

208

Joint Student Seminar on Civil Infrastructures

STIFFNESS CHARACTERISTICS OF
VANISHING MIXTURES
Q. HUNG TRUONG, YONG-HUN EOM and JONG-SUB LEE
Civil, Environmental and Architectural Engineering,
Korea University, Seoul, 136-701, Korea
jongsub@ korea.ac.kr
ABSTRACT
Particle dissolution is a natural phenomenon that may happen andcause changes in microstructure of particulate media, such as the increaseof local strain and permeability. The study focuses on stiffness
characteristics of vanishing materials modeled by particulate mixtures ofsand and salt at different fractions. Experiments are carried out in aconventional oedometer cell integrated with bender elements. Saturation
process used to dissolve the salt particles in the mixtures are implemented
at different confining stresses. Axial deformations and shear wave signals
are recorded after each loading stage and during saturation process.
Experimental results showed that microstructural changes due totransformation of form of particles were greatly effect to the stiffness of
mixtures. Specimens prepared by sand and salt are proved to be able toprovide a valuable insight in macrostrucral behaviors of the mixtures.

1. INTRODUCTION
Geology, climate and environment have a great influence on formations ofsoil. There may be ingredients of soluble minerals in engineered soils that
may be under the foundation or inside an earth structure, etc. A vanishing
mixture usually consists of soil particles and vanishing materials, such as
salt, gypsum, anhydrite, dolomite, and halite, etc. Effects of the dissolution
materials in engineering mixtures have been studied by many researchers invarious aspects:- Craft et al. (2005) developed a guide to planning seepage chemistry
investigations for dam effected by dissolution of soluble materials.
- Fam et al. (2002) addressed mechanical properties changes of sands
subjected to local strain increase created by washing salt in sand-salt
mixtures.
- Azam (2000) focused on compressibility and collapse of calcareous
clay represented by mixtures of clay and highly soluble calcium
sulphate.
Changing phase of particle may play an important role in mechanicalbehaviors of soil. Dissolution of particle, which may cause changes in
microstructure of particulate media, produces the local void increase.
Mechanical properties of material in macroscale may be subjected to a large
effect as loosen. Besides, void ratio increase will increase the permeability

209

July 2008, Thailandof soil which may raise problem for an earth structure with the present ofvanishing mixtures inside.
This study addressed the small and large strain engineering propertiesof the soluble mixtures in Ko-loading conditions by using a conventional
cell equipped by bender elements. Experiments using oedometer cell withbender element have been widely used and graduatedly become one ofstandard tests for soil properties. Many researchers contributed to thedevelopments of this test:- Fam and Santamarina (1995) studied the small strain stiffness ofsand in Ko loading condition.
- Yun and Santamarina (2005) captured the changes in small strain
stiffness of loose soil during decementation and softening process andcollapse.
- Lee et al. (2007a) focused on effect of mica to mechanical behaviors
of sand soils.
- Lee et al. (2007b) studied behaviors of rigid-soft mixtures (fine sandrubber particle) during cementation and uncementation,
decementation.
This paper starts with the experimental program that was performedon sand-salt mixtures to demonstrate the effect of dissolved material in
mixtures. Following is experimental results and discussions. Finally, someconclusions are cited out.

2. EXPERIMENTAL PROGRAM
2.1 Sample preparation
Uniform, fine, quite round sand (Jumunjin 40/50 sand) with D50=
0.36mm, Gs= 2.62 was used to evaluate the effect of vanishing material tomechanical behavior of soils. Uniform, fine, hexagonal grain salt (50/70)
with D50= 0.25mm, Gs= 2.16 was mixed with sand at 0, 2, 5, 7, 10%
mixing ratios in volume. Microscopic particle images of the sand and salt
particle are shown in Figure 1. Salt particles were selected finer than sandparticles to minimize the corresponding change in total volume during thesalt dissolution stage. Specimens are prepared at same initial void ratio forsaturation to create local void due to salt dissolution at different confining
stress during Ko loading.
The sand is oven dried overnight before testing. Sand and salt wereplaced in two papers, and then they were poured at the same time to acontainer to create homogeneous specimens. Then, the mixture is mixed in 5
minutes and funneled carefully into the oedometer cell in 5 layers. The same
weight of mixtures is added to form each layer when tamping is used toattain initial designed dense condition (e0= 0.76).

210

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

500um

Figure 1: Sand and salt particle images: (a) sand; (b) salt
2.2 Device
The effects of local void on the small and large strain mechanicalproperties of the materials were explored by implementing shear wave
measurement in a conventional oedometer cell equipped with benderelement. The oedometer cell is 74mm in diameter and 63mm in height. The
bender elements integrated on the top cap and the bottom plate of theoedometer cell were used to excite and capture shear waves. The dimensionof bender elements is about 5 mm in cantilever length and 5 mm in width.
Figure (2) shows the detailed sketch of the experimental system. Discussion
on bender element configuration and performance can be referenced in Lee
and Santamarina (2005)

Filter-Amplifier
OscilloscopeComputerB
Sand-salt mixture
B
Water flow
Signal Generator
SIGN

Figure 2: Experiment setup
The 20 Hz square signals were delivered from the signal generator(Agilent 33220A) to the sourced bender element. Shear waves emitted fromthe source and traveled through the specimen were captured andtransformed into the electrical signal in the receiver bender element. The
electrical signal was fed through a filter-amplifier (Krohn-Hite 3944). The
cutoff frequency for the low-pass filter is 100 kHz, ten times grater than thehighest resonance frequency to ensure the Nyquist condition. The filteredand amplified signal was digitized through an oscilloscope. Note the 1024
signals were usually averaged to remove the high frequency uncorrelated
noise. Since this technique takes time, at least 10 second, for each stable andStiffness Characteristics of Vanishing Mixtures

211

July 2008, Thailand

accuracy measurement, the signals during saturation stage to dissolve
soluble materials ware captured without averaging in the first 30 minutes.
Well designed of shielding to prevent the emissions of electromagnetic
waves can help to obtain clear signals.
2.3 Test procedure
Ko loading with three stages, loading, unloading and reloading, werecarried out. The normal stress was doubled at each loading stage duringloading test. Four specimens were saturation to dissolve salt at different
effective confinement stress level and one without salt dissolution (i.e.
testing is conducted in dry condition). The other five specimens, with thesalt fraction changed from 0, 2, 5, 7, 10% are carried out at the same
confining stress for dissolving. The electrolyte NaCl 0.01M is slowly andcarefully poured into consolidation cell to minimize the total change of
specimen due to saturation process. Salt grains were dissolved at the confine
stresses of 41, 80, 158 and 315kPa. Each loading stage lasted for 30 minutes
except the loading stage with saturation lasted for 1000 minutes.

0

0

0

0.1

0.2

0.3

Time [ms]

0.4

0.5

0

0.1

0.2

0.3

0.4

loading
unloadingloading00Saturation0

unloading00reloading

0

1 kPa
6 kPa
11 kPa
21 kPa
41 kPa80 kPa158 kPa
315 kPa629 kPa
315 kPa
158 kPa
80 kPa
41 kPa
21 kPa
11 kPa
6 kPa
1 kPa
6 kPa
11 kPa
21 kPa
41 kPa80 kPa158 kPa
315 kPa629 kPa0

reloading

1 kPa
6 kPa
11 kPa
21 kPa
41 kPa80 kPa158 kPa
315 kPa629 kPa
315 kPa
158 kPa
80 kPa
41 kPa
21 kPa
11 kPa
6 kPa
1 kPa
6 kPa
11 kPa
21 kPa
41 kPa80 kPa158 kPa
315 kPa629 kPa0

0.5

Time [ms]Figure 3: Shear wave signals gathered during loading, unloading,and reloading stages: (a) sand-salt specimen without salt dissolution;(b) sand-salt specimen with salt dissolved at 79.90kPa. The numbers
in figure denote the applied vertical effective stress [kPa].

212

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

2.4 Shear wave velocity
Shear wave is recorded at the end of each loading or unloading stage.
Shear wave velocity is calculated based on the travel distance and travel
time. The travel times, from tip to tip of source and receiver, are pickedfrom recorded traces in consideration of near field effects (Lee andSantamarina 2005). The travel distance L is equally to the tip-to-tip distance
between these bender elements. Finally, the shear wave velocity iscomputed as Vs = L/ttip-to-tip.

0

unloading loading

0

0

0

0

0

reloading00Time [ms](a) sf=0%(b) sf=2%(c) sf=5%(d) sf= 7%(e) sf = 10%

Figure 4: Shear wave signatures of specimens with different salt fractions
saturated at same confining stresses.

3. RESULTS AND DISCUSSIONS
0.035

210

41 kPa80 kPa158 kPa
315 kPa

0.02
0.015

Vs

Vertical strain

230

0.025

190

0.01

170

0.005

150

0.01

41 kPa80 kPa158 kPa
315 kPa

250

0.03

0.1

10
1
Time [min]

100

1000

130

0.01

0.1

1
10
Time [min]

100

1000

Figure 5: Saturation stage: (a) Axial strain versus time; (b) Shearwave velocity versus time for salt particle dissolved at different
loading stages. The sketched solid line shows the general trend ofshear wave velocity during saturation stage.
The measured shear wave signals were plotted versus time duringloading, unloading and reloading in specimens with and without saltdissolution in Figure 3. The following observations can be made:- The increase in travel time after vanishing process denotes thedecrease in small strain shear stiffness of sand specimen.

Stiffness Characteristics of Vanishing Mixtures

213

July 2008, Thailand- The shear wave signals after the salt dissolved is smoother than thesignals obtained before dissolution happen and in the specimen
without dissolution. It is because that the salt particles (finer thansand) were dissolved, the specimen was more homogenous after
saturation. The vanishing of salt, finer particle, worked as a high passfilter here.
The signatures of shear waves of vanishing mixtures with different
salt fractions at the same confining stress for saturation process are shown in
Figure 4. Since the salt fraction increase, the band of response signals are
increase. It is right because the specimen become softer as the salt fraction
increases.

0.95

0.90

0.90

0.80

End

0.75 Start
End
0.70
1

10

100

Effective stress [kPa]

1000

End

0.85

0.80

Saturation

No water
80 kPa0.85

Void ratio e

0.95

SaturationVoid ratio e

After the saturation, all salt particles dissolved. Although the tip-to-tip
distances between top and bottom bender elements reduce due to thesettlement caused by the salt vanishing, the travel times of shear wave still
increase. It means that there is a reduction on effective stress acting
normally on bender elements and/or an increase in real travel length of shear
wave. The travel length of shear wave may increase due to the increase of
local voids. Here, the specimen is sand, the effective stress keep constantbefore and after the salt dissolution due to its high permeability properties.
Therefore, the real travel length of wave in particle level increases due tothe particle contact area reduces. The effect of density is not a key factor
here because when the salt particles dissolved, the sand particles moved to
the new void area. Even though, the void occupied by sand is not so muchbecause the sand is bigger than salt. So that, the density may be reduce alittle.

0.75 Start

0.70
1

10
100
Effective stress [kPa]

1000

Figure 6: Consolidation test for sand-salt mixtures :0, 2, 5, 7, 10%
during loading stage with and without salt dissolved at effective
stress of 41, 80, 158, 315kPa.: (a) typical e v.s. effective stress; (b) ev.s. effective stress.
Figure 5 shows the change of axial strain and shear wave velocity
during the saturation stage. The history of shear wave velocity during
saturation stage can be divided into three periods. In the first period, from214

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

0~0.2 minutes after saturation started, the axial strain and the velocity ofshear wave tremendously reduced. It means that there is a large effect of thewater flow and the vanishing of salt particle on the specimen during thisperiod. In the second period, from 0.2~10 minutes, since there is only effectof salt dissolution, the shear wave velocity slowly reduced and increased.
Firstly, the shear wave velocity reduced because the effect of salt vanishingoverwhelmed the effect of loading, the void ratio increase. Then the local
void ratio reduced because the loading was prevailing. As a result, the shear
wave velocity was increase. After 10 minutes, shear wave velocity almost
gets to a stable value because the salt dissolution process almost finished.
There is no or very small effect of salt dissolution. The effect of salt
vanishing largely happened in the first ten minutes. In this measurement, notonly the effect of local void ratio changed due to salt dissolution but also thewater diffusion had been investigated.
The evolutions of void ratio and shear wave velocity are plottedversus effective stresses for the specimens with and without salt dissolution
in Figure 6 and 7. It can be seen that:- Void ratio always increases and shear wave velocity always
decreases after saturation stage at any load steps of this sand-salt mixture.
- Compression and recompression coefficients, cs and cc, of
specimens with and without salt dissolved are nearly same.
- While the shear wave velocity versus effective stress shown theunstable value among specimens, the void ratio versus effective stressgraphs show a consistent value. It means that the shear wave velocity can
detect the non-homogeneous level of specimen locally while the The void
ratio versus effective stress graph could not show the non-homogenous of
specimen
350
330

No water
80 kPa

300

End

280
Vs [m/s]Vs [m/s]

250
200

180

150
100
50

230

Start

130
Start

1

10

100

Effective stress [kPa]

1000

80
1

10

100

1000

Effective stress [kPa]

Figure 7: Consolidation test for sand-salt mixtures: 0, 2, 5, 7, 10%
during loading, unloading and reloading stage for specimens with andwithout salt dissolved at 41, 80, 158, 315kPa: (a) typical Vs vs.
effective stress for 2 specimens: no saturation and saturated at 80
kPa; (b) Vs vs. effective stress in loading stage for all specimens.

Stiffness Characteristics of Vanishing Mixtures

215

July 2008, Thailand

4. CONCLUSIONS
Changes in small-strain shear stiffness in k0 loading of sand subjected to
local void ratio increase were investigated by conducting shear wave
measurements in conventional oedoemeter cell with bender elements. The
main observations from this study follow:- During saturation stage in which the salt particle dissolved, shear
wave velocity reduces dramatically at the first 0.2 minutes, and then reduces
and increase slowly at the next 10 minutes, and finally gets to stable. The
effect of salt dissolution to specimen almost happens at the first ten minutes.
- Smaller particle vanishing works as a high pass filter.
- Shear wave measurement clearly captures the microstructuralchanges due to particle dissolution.
- Sand-salt mixture is useful for laboratory test on controlled artificial
specimen.

ACKNOWLEDGMENTS
This work was supported by BK-21 Global Leaders in Construction
Engineering, Korea University, Korea.

REFERENCES
Azam, S., 2000. Collapse and compressibility behaviour of arid calcareous
soil formations. Bulletin of Engineering Geology and the Environment,
Springer Berlin, 59(3).
Craft, D., Cain, C. and Sullivan, C., 2006. Seepage Geochemistry andMineral Dissolution at Clark Canyon Dam, Pick-Sloan Missouri
Basin Project, East Bench Unit, Montana. Technical Memorandum
86-6829010, U.S. Department of the Interior - Bureau of Reclamation,
Denver, Colorado, p 48.
Craft, D., 2005. Seepage Chemistry Manual. Report DSO-05-03, US
Department of the Interior, Bureau of Reclamation, Dam Safety
Technology Development Program, Denver, Colorado, p 76 pp.
Fam, M. A., Cascante, G., and Dusseault M. B., 2002. Large and Small
Strain Properties of Sands Subjected to Local Void Increase. J.
Geotech. Geoenviron. Eng., ASCE, 128(12), 1018-1025.
Lee, J. S. and Santamarina, J. C., 2005. Bender elements: performance andsignal interpretation. J. Geotech. Geoenviron. Eng., ASCE, 131(9),1063-1070.
Lee, J.S., Guimaraes, M., and Santamarina, J. C., 2007. Micaceous sand:Fabric, stiffness, and strength. Journal of Geotechnical andGeoenvironmental Engineering, ASCE, 133(9), 1136-1143.
Lee, J.S., Dodds, J., and Santamarina, J.C., 2007. Behavior of rigid-soft
particle mixtures. Journal of Materials in Civil Engineering, ASCE,
19(2), 179-184.
Santamarina, J. C., Klein, K. A., and Fam, M. A., 2001. Soils and Waves –216

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Particulate Materials Behavior, Characterization and Process
Monitoring. JohnWiley and Sons. New York.
Yun, T.S. and Santamarina, J.C., 2005. Decementation, softening andcollapse: Changes in small-strain shear stiffness in Ko-loading.
Journal of Geotechnical and Geoenvironmental Engineering, ASCE,
131(3), 350-358.

Stiffness Characteristics of Vanishing Mixtures

217

July 2008, Thailand

218

Joint Student Seminar on Civil Infrastructures

OD VARIATION ANALYSIS ON THE
TOKYO METROPOLITAN EXPRESSWAY
USING ETC-OD DATAHIROAKI NISHIUCHI
Doctoral Course of Department of Civil Engineering,
University of Tokyo, JAPANnishiuch@iis.u-tokyo.ac.jp
ABSTRACTThis research analyzes origin-destination traffic volumes (OD) on theTokyo Metropolitan Expressway (MEX). The aim of this study is tounderstand the characteristics of daily OD variation since such kind ofknowledge is crucial for short-term OD prediction. The OD data in thisstudy is obtained by electronic toll collection (ETC).
Aggregated 12 hours (7am to 7pm) and hourly OD were analyzed byanalysis of variance (ANOVA) and multiple comparisons. Results show, themain factor of 12 hours’ OD variation is the day of the week, and hourly
OD varies by the day of week. Therefore, day of week and time of day areused as explanatory variable for estimating OD volumes using a Bayesian
Network. The estimation results show that the model is able to estimate
average OD volumes.

1. INTRODUCTION
Recently, usage of dynamic traffic information is recommended to mitigate
the traffic congestion by Dynamic Traffic Management. At the Tokyo
Metropolitan Expressway (MEX), they are developing real time traffic
simulation system, using dynamic origin-destination (OD) volumes.
Current OD traffic volumes are based on census survey result, carried out at
one day in several years. Therefore, it is difficult to reflect the real timetraffic condition in the simulation system.
In Japan, electronic toll collection (ETC) is applied on expressways.
Drivers with an ETC on-board unit in their car, do not have to stop at tollgates and the payment is done electronically when the vehicle passes thesensors. The ratio of ETC users smoothly increased, being now 80% ofdrivers on MEX (2008). The system records the usage of on-ramps and offramps. With that, we can acquire the origin and destination of drivers.
Aggregating this information, we obtain time-dependent OD volumes whichhave been a difficult task until now.
Since OD Data from ETC records are time-dependent and huge inamount, we can identify the characteristics of OD volume variation and the219July 2008, Thailand

significant factor for that variation. Researchers e.g. IIDA (1981), RAKHA(1995) have tried to identify these through link flow variation. However,
without measured OD data there was no final proof. Therefore, this researchaims to be a foundation for future OD volume estimation from historical OD
pattern.
In this paper, characteristics of OD variation are discussed with daily
OD variation using 12 hours aggregated and hourly OD volume. Then thisknowledge will be used for short-term OD prediction which is still in apreliminary stage.

2. ETC-OD DATAETC-OD Data used here is collected from June 2006 to December 2006
(157days in this period). Time-period of data collection is 12 hours (from
7am to 7am). In this research, we used aggregated ETC-OD Data as 30
minutes, 1hour and 12hours aggregation.
Toll system of MEX is used fixed price system. Therefore, price of
toll is decided depending on toll area e.g. Tokyo toll area, Kanagawa tollarea and Saitama toll area. That means when driver travel from Tokyo to
Kanagawa, they need to pay again at mainline toll gate which is located on
border of each toll area. However, we focused on trips in same price area inthis study e.g. travel in Tokyo toll area. Using above definition of data,
number of target OD pair become 6729.

3. DAILY OD VARIATION
3.1 Characteristics of daily OD variation
To know how 12hours OD traffic volume normally varying,coefficient of variance is evaluated. Coefficient of variance is calculated by
(1).

CV =
i

Var
E
∑ (E − x )

(1)

i

i

N

Var =
i

n =1

n

i

2

(2)

i

N

where,CVi : Coefficient of Variance of OD pair i
Vari : Variance of OD pair i
Ei : Averaged 12 hours OD traffic volume of OD pair i

xin : 12 hours OD traffic volume of OD pair i of day n
N : Number of available days = 157days in this paper

220

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

4

1

3.5

0.9
0.8

3

0.7

2.5

0.6

2

0.5

1.5

0.4
0.3

1

0.2

0.5

0.1

0
0

Cumulative Number of OD Pairs

Coefficientof Variance
変動係数

Figure 1 shows the relationship between averaged weekday’s 12hours
OD traffic volume and its coefficient of variance, and cumulative number of
OD pair. Blue dot represents one OD pair, and pink line is cumulative
number of OD. From the figure, if averaged 12hour OD traffic volume is
low level, its coefficient of variance is high, but if OD traffic volume levelis increase, its coefficient of variance is low level. And according to shapeof cumulative number of OD, about 90% of OD pair are less than120[veh/12hours]. That means OD traffic volume is normally varying e.g.
when OD traffic volume is greater than 500[veh/12hours], coefficient ofvariance is around 10%.

0500 1000 1500 2000 2500 3000 3500 4000 4500 5000
平均O DOD
交通量[veh/12hours]
Average
Traffic
Volume [veh/12hour]

Figure 1: Relationship between averaged weekday’s OD traffic volume andits coefficient of variance, and cumulative number of OD pair
3.2 Factors of daily OD variation
The factor of 12 hours OD variation is specified in this section.
Following indexes are chosen as the factor of daily OD variation. To
confirm they can be the factors, one-way Analysis of Variance (ANOVA) is
implemented. The output of ANOVA tells us whether there is significant
difference between categories of each factor. Therefore, if ANOVA shows
significant difference to each category of the factors, the factors affect tovariation of 12 hours OD traffic volume.
Factor 1: Weekday and Holiday
Factor 2: Weekdays (Monday, Tuesday, Wednesday, Thursday, Friday)
Factor 3: Holidays (Saturday, Sunday, Holidays including middle ofAugust*)Factor 4: Daily inflow of MEX
Factor 5: Daily amount of jam of MEX
Factor 6: Season
Factor 7: Daily amount of rain at Tokyo
Factor 8: Daily number of accident at MEXOD Variation Analysis on the Tokyo Metropolitan Expressway Using ETC-OD Data

221

July 2008, Thailand* Many Japanese take holiday during middle of August.
Since Number of target OD pair here is 6729, results should be
different tendency depending on level of average 12hours OD traffic
volume. Therefore grouping by average 12 hours OD traffic volume are
implemented. The definition of grouping and number of OD at each groups
are shown in Table 1.

Table 1: Number of OD at each group
Group (Definition of group)
Number of OD pair
120
High (Ei ≧ 500 [veh/12hour])
1077
Middle (500 >Ei≧ 50 [veh/12hour])5532
Low (500 >Ei≧ 50 [veh/12hour])
Figure 2 shows the ratio of number of significant OD at each factor.
From the results, “Weekday vs. Holiday”, “Weekday”, “Holiday”, “Daily
Inflow” and “Daily Amount of Jam” are significantly different distributionof OD traffic volume by each category, especially High and Middle of OD
traffic volume groups.
On the other hand, “Season”, “Rain” and “Accident” are notsignificant at all of group. “Season” was difficult to show the significancesince number of days for analysis is 157 days. Therefore, analyzing“season” by adding data of another month is strongly recommended. In caseof “rain” and “accident”, they are also possible to have impacts to traffic inmore short time-period. However 12 hours data are evaluated here, therefore
when dynamic OD traffic volume is evaluated, these factors’ impact should
be considered.
WEEKDAY vs HOLIDAY
1
ACCIDENT[per day]

0.8

HIGH [120 OD]
MIDDLE [1077 OD]
LOW [5532 OD]

WEEKDAY

0.6
0.4
0.2

RAIN
[mm/day]0

HOLIDAYDAILY INFLOW[veh/day]

SEASONDAILY JAM [veh・km]

Figure 2: Ratio of number of significant OD at each factor

222

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

3.3 The difference between each day of weeks
In previous section, the analysis showed that weekdays are importantfactor of daily OD variation. However, ANOVA didn’t mention which
combinations of day of week are significantly different. Therefore, multiple
comparisons are implemented to see the difference between all of
combinations of day of week.
Table 2 shows the number of OD pair which is significant different
combination of day of week. From the table, if Friday is compared withanother day of week, then more than 20% of OD pairs have statisticallydifferences in case high and middle level group. However Thursday andFriday are not significantly difference, and there is no significantly
difference in low level of OD traffic volume group. It can be considered thatmost of low traffic volume’ OD are varying as just random, therefore it isdifficult to define normal distribution and to find significance.

Table 2: The ratio of number of significant OD by multiple comparisons

HIGH
MIDDLE
LOW

MON
vs
TUE

MON
vs
WED

MON
vs
THR

MON
vs
FRI

TUE
vs
WED

TUE
vs
THR

TUE
vs
FRI

WED
vs
THR

WED
vs
FRI

THR
vs
FRI

0.10
0.03
0.03

0.14
0.07
0.00

0.23
0.10
0.03

0.59
0.31
0.08

0.04
0.03
0.02

0.06
0.03
0.01

0.43
0.21
0.04

0.03
0.03
0.02

0.35
0.24
0.05

0.13
0.08
0.03

On the other hand, RAKHA (1995) mentioned that Monday also
should have significant difference with from Tuesday to Thursday.
However, the result here Monday is not really different with other days. The
one of reason can be problem of aggregation by 12hours, and then it ispossible that the significance can appear using OD data aggregated by timeof the day. Therefore same analysis using hourly OD traffic volume isimplemented. Figure 3 to 5 shows the results of multiple comparisons bytime of the day, and graphs shows the results in case “Monday vs.
Tuesday”, “Monday vs. Wednesday” and “Monday vs. Thursday”.

OD Variation Analysis on the Tokyo Metropolitan Expressway Using ETC-OD Data

223

July 2008, Thailand

Monday vs Tuesday

0.4High [120 OD]
Middle [1077 OD]
Low [5532 OD]

Ratio of Significant OD

0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
7

8

9

10

11

12

13

14

15

16

17

18

Time [7am-7pm]

Figure 3: Ratio of number of significant OD by time of the day[Monday vs. Tuesday]
Monday vs Wednesday
0.4High [120 OD]
Middle [1077 OD]
Low [5532 OD]

Ratio of Significant OD

0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
7

8

9

10

11

12

13

14

15

16

17

18

Time [7am-7pm]

Figure 4: Ratio of number of significant OD by time of the day[Monday vs. Wednesday]

224

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Monday vs Thursday
0.4High [120 OD]
Middle [1077 OD]
Low [5532 OD]

Ratio of Significant OD

0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
7

8

9

10

11

12

13

14

15

16

17

18

Time [7am-7pm]

Figure 5: Ratio of number of significant OD by time of the day[Monday vs. Thursday]
The results at 7am to 9am in all figures of high level of OD traffic
volume group has significant different, but not in another OD group.
Therefore, the time of the day is also important factor for explaining OD
variation.

4. OD ESTIMATION USING FACTOR OF DAILY OD VARIATIONOD variation is mainly affected by day of the week and time of the day.
Therefore, in this chapter, the example of usage of this knowledge is shownby estimating dynamic OD traffic volume using Bayesian Network model.
4.1 Bayesian Network Model
Bayesian Network Model (BN) is the stochastic model by using
acyclic network structure as shown at Figure 6. Figure 6 is described aexample of BN structure and conditional probability table (CPT) which is
output from BN. BN consist by son node and parent node, and parent node’s
conditional probability is calculated depending on condition of their son
node. For example, if we want to estimate x1, it depends on condition of x2,x3 and x4 as CPT in Figure 6.

OD Variation Analysis on the Tokyo Metropolitan Expressway Using ETC-OD Data

225

July 2008, Thailand

x5

x4

x6

x2
x3
x1
CPT of P ( x1 | x 2 , x 3, x 4 )

x2

0

x3
x4
x1

1

0

1

0

1

0

1

0

1

0

1

1

1

0

0.2

0.3

0.1

0.15

0.6

0.65

0.7

0.8

1

0.8

0.7

0.9

0.85

0.4

0.35

0.3

0.2

CPT: Conditional Probability Table

Figure 6: Example of Bayesian Network Model and CPT
4.2 OD Estimation using ETC-OD Data
To estimate dynamic OD traffic volume using BN, day of the week
and time of the day is chosen as son node of 30 minutes OD traffic volume.
The 133days ETC-OD data set are used for calculating CPT. Figure 7 is the
BN structure, and the conditional probability of 30 minutes OD traffic
volume occur is calculated. And then the expected value of 30min OD
traffic volume is calculated using the CPT.
Day of Week

Time of Day

30minOD
VolumeFigure 7: Bayesian Network Model for estimating 30minutes OD
Monday’s 30 minutes OD traffic volume from 7am to 7pm isestimated as shown at Figure 8. The blue line represents an estimation
result, and another 3 lines are each Monday’s on December 2006 OD traffic
volume profile. The estimation result can follow only the tendency of each
Monday’s profile since there is no dynamic information in the model for
representing each of the day and the time. And then estimation result
couldn’t describe details of OD traffic volume profiles. Therefore, OD
estimation using BN including the dynamic information is recommended to
improve their accuracy e.g. Travel Time between OD at the time, accident
information at the time and so on.

226

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

180
EstimatedOD Traffic Volume [veh/30min]

160

4th Dec

11th Dec

18th Dec

140
120
100
80
60
40
20

18
18
.5

17
17
.5

16
16
.5

15
15
.5

14
14
.5

13
13
.5

12
12
.5

11
11
.5

10
10
.5

9
9.5

8
8.5

7
7.5

0

Time of Day

Figure 8: Profile of Estimated OD traffic volume and Monday’s OD traffic
volume on December 2006

5. CONCLUSION
In this paper, 12 hours OD traffic volume is analyzed to understand thefactor of its variation by implementing ANOVA and Multiple Comparisons.
ANOVA showed some differences that Weekdays and Holidays aredifferent variation, and weekdays also have different tendency in each dayof week. Especially Friday‘s OD traffic volume has different distribution
with the other weekdays. And Multiple Comparison using hourly OD traffic
volume showed Monday’s OD traffic volume is also different tendency with
Tuesday, Wednesday and Thursday. Therefore, day of week and time of day
were important factor of OD variation.
And OD traffic volume is estimated using Bayesian Network Model.
The result could not represent one day’s OD traffic volume since dynamic
information was not included to the model. Therefore improving the modelis strongly recommended through empirical analysis of dynamic OD traffic
volume e.g. Temporal-Spatial OD correlation, Impact of traffic condition to
OD traffic volume and so on.

REFERENCES
H. RAKHA., M. VAN AERDE, 1995. Statistical Analysis of Day-to-Day
Variation in Real-Time Traffic Flow Data. Transportation Research
Record 1510, 26-34.
Website of Ministry of Land, Infrastructure, Transport, 2008.
http://www.mlit.go.jp/road/yuryo/riyou.pdf
Y. IIDA., J. TAKAYAMA., 1981. A Statistical Analysis of Characteristics
of Traffic Flow on Expressway. Expressway and Automobile, Vol.24,
22-32.

OD Variation Analysis on the Tokyo Metropolitan Expressway Using ETC-OD Data

227

July 2008, Thailand

228

Joint Student Seminar on Civil Infrastructures

STUDY OF PROPERTIES OF PARA-RUBBERPLATES FOR USING AS THE CAPPING ON
CONCRETE SPECIMENS FOR COMPRESSIONTEST INSTEAD OF MOLTEN SULPHERKITTIPONG SUWEERO and PRACHOOM KHAMPUT
Department of Civil Engineering, Faculty of Engineering,
Rajamangala University of Technology Thanyaburi,
Pathumthani, Thailand
siam_macho@hotmail.com
ABSTRACTThis paper aims to study the using para-rubber plate for transferring
the force on concrete specimens instead of capping with sulphur. Four
formulas for mix design of para-rubber plate are setup. Each formula ismixed in two rolls mill machine and formed the para-rubber plate byCompression Molding. After obtaining the para-rubber plate specimens, themeasuring of compression set, tensile strength, % strain, tear strength,
hardness of para-rubber plate are performed. Consequently, the pararubber plates are taken into capping the concrete and tested thecompressive strength. These results are compared to that with sulphur
capping. From the results, it is found that adding carbon black over 60 phr
affects to develop the hardness but the other properties are declined. In
testing the compressive strength of concrete with para-rubber plate, it isfound that the formula that gives the results close to that using of sulphur isthe formula that uses latex at 100 phr, carbon black (grade N330) at 100
phr and calcium carbonate at 50 phr. In this formula, the compressive
strength is larger than using sulphur at 7%. This indicates that there ispossibility in developing the formula of para-rubber plate for capping
material in the future.

1. INTRODUCTION
Normally, there are 2 types of compressive tests of the concrete. One is teston the cubic of size 15x15x15 cm. (BS 1881 part 108) (British Standard
Institute, 1983) This method uses widely in Europe. Another method which
extremely uses in America, France, Canada, Australia and New Zealand
performs on cylinder at diameter 15 cm. and height 30 cm. according to
ASTM C192 ((American Society for Testing and Materials, 2001). The
tested concrete must be capped with cement paste or plaster cement orsulphur ((American Society for Testing and Materials, 2001). Among three
types of capping materials, the sulphur is mostly exploited. However thesulphur is the toxic substance which can harm the respiratory system of theusers, then many organizations replace the using of sulphur in capping
concrete with the other materials such as synthetic-rubber plate with steel

229

July 2008, Thailand

case (see Figure 1a). We can find the synthetic-rubber plate from bothaboard (see Figure 1b) and in the country. However the price of syntheticrubber from aboard is relatively high, then there is an attempt on research
the new materials for capping the concrete instead of sulphur (P.M. and R.L.,
1988, Grygiell and Amsler, 1977, Khamput and Boksuwan, 2006, Anusiri,2006) The results from those studies are still unsatisfied. Thus in thisresearch, we look for the formulae of para-rubber (from latex in Thailand)
plate. The compressive strengths of purposed rubber plate will be comparedto those with sulphur for finding the suitable formula which gives the results
close to those using the sulphur.
LoadPara-rubber platewith steel case
Concrete
specimen:(a)(b)

Figure 1: a ) Loading of para-rubber plate with steel case.
b ) Fiber reinforced synthetic rubber-plate from aboard.

2. METHODOLOGY
2.1 Materials and equipments
1) Para-rubber no. STR20: the characteristics of this type of pararubber arei) There is the double bond.
ii) There is the alpha-methylene which makes the vulcanizing
reaction with sulphur. The properties of this para-rubber are shown in Table 1.
2) Sulphur that serves as vulcanizing agent (or curing agent). The
benefit of adding sulphur is to make the link between molecules of rubber.
3) Carbon black of four grades according to ASTM D1765 (N220,
N330, N550 and N660). The properties of carbon black in each grade aresummarized in Table 2.
4) Calcium carbonate (CaCO3).
5) Two-roll mill.
6) Compression Molding.
7) Tension machine.
8) Shore durometer.
9) Universal testing machine.
10) Steel case.

230

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Table 1: Specification of STR 20 Rubber (Sae-Oui, 2004)
Specification
The contaminations that are larger than
44 micron (max%wt)
Ash (max % wt)
Nitrogen (max % wt)
Vaporous matter (max % wt)
Initial plasticity (PO) (min)Plasticity Retention Index (PRI) (min)Mark color
Color of film (LDPE)
Color of polyethylene

Standard Value
0.16
0.80
0.60
0.80
30
40
Red on with surface
Transparency
White

Table 2: Properties of Carbon Black.
Fundamental properties
Iodine absorption (g/kg)
ASTM D1510
Nitrogen absorption (m/g)
ASTM D3037
DBPA (cm/100g)
ASTM D2414
DBPA of compressed sample(cm/100g), ASTM D3493
CTAB (m/g),
ASTM D3765

N220

Carbon Black
N330
N550

N660

121

82

43

36

119

83

42

35

114

102

121

90

100

88

88

75

111

83

42

35

2.2 Research methodology
The methodology is divided into three sections: i) By using only
carbon black as a major component in producing the para-rubber plate, themost suitable grade of carbon black will be selected according tofundamental properties of carbon black (Table 2) and mechanical properties
from testing under ASTM standard (American Society for Testing andMaterials, 1996). ii) By using calcium carbonate (CaCO3) and carbon black,the CaCO3 is added for reducing the cost of carbon black. The 3 ratios ofcarbon black to CaCO3 are given and tested similar to the first case. iii) The
para-rubber plates from sections 1 and 2 are taken into capping the concrete
specimens with steel cases and examined the compressive strength under
ASTM C39 (American Society for Testing and Materials, 2001). The resultsfrom two types of para-rubber plates are compared for selecting theappropriate formula. Before explaining the step of forming para-rubber plate,
it is important to note that the unit of defining the quantity of substances inthis paper is phr or pphr (part per hundred of rubber). For example, carbon
black 50 phr means there are 50 parts of carbon black per 100 parts ofrubber. The steps of forming the para-rubber plate are shown below.
1. Mastication in open system and at temperature 30-70 degree
Celsius, the chemical substances such as carbon black, CaCO3 and sulphur

Study of Properties of Para-Rubber Plates for Using as the Capping on Concrete Specimens forCompression Test instead of Molten Sulphur

231

July 2008, Thailand

were added respectively. After complete mixing, we obtained the rubbercompound.
2. The rubber compound was formed by hot rolling at temperature
160 degree Celsius.
3. The para-rubber plate was cooled down and then we had the pararubber plate that has 15 cm. in diameter and 1 cm. in thickness.
4. The following mechanical properties were evaluated using the
ASTM standard (American Society for Testing and Materials, 1996).
-

Compression set (ASTM D395)
Tensile strength (ASTM D412)
Strain (ASTM D412)
Hardness (ASTM D1415)
Tear strength (ASTM D624)

5. The concrete specimens were capped with para-rubber plates andtested the compressive strength of the concrete. The results were comparedto those with sulphur capping. Each formula had 30 specimens for finding
the average value of compressive strength. The strength of concrete in mix
design is 280 ksc.
The symbols for testing are listed in Table 3. The readers should keep
in mind that all of quantities in Table 3 are compared with 100 parts of pararubber.
Table 3: The Symbols in this research.
SymbolDefinition

S

Sulphur

60N:0C

Carbon black 60 parts per CaCO3 0 part

60N:50C

Carbon black 60 parts per CaCO3 50 parts

80N:50C

Carbon black 80 parts per CaCO3 50 parts

100N:50C

Carbon black 100 parts per CaCO3 50 parts

3. RESULTS
The mechanical properties of para-rubber mixed with carbon black areshown in Table 4 and Figure 3.

232

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Table 4: Mechanical properties of para-rubber plate with carbon black.
Compressionset (%)

N220
N330
N550
N660
N220

76
74
62
66
76

Tensile Strength (MPa)

GradesMechanical Properties
TensileStrainHardness
strength(%)(Shore D)
(MPa)
14
478
64
13
451
65
13
474
64
12
428
60
14
478
64

16
14
12
10
8
6
4
2
0

Tear
strength(N/mm)
64
53
43
36
64

N220
N330
N550
N660
0 100 200 300 400 500 600% Strain

Figure 3: Stress strain relationship of para-rubber plate.
The important property of para-rubber plate is the hardness so it isconsidered as a major property in selecting the para-rubber plate. From
Table 2, para-rubber plate with carbon black N330 gives the maximum
hardness (measures from Shore D (Na-Ranong, 2001.) and the otherproperties are in acceptable range (see Figure 3), then we select the carbon
black grade N330 as a filter in this research.
The mechanical properties of para-rubber plate with carbon blackand CaCO3 are shown in Table 5. The CaCO3 is added for reducing the costof para-rubber plate.

Study of Properties of Para-Rubber Plates for Using as the Capping on Concrete Specimens forCompression Test instead of Molten Sulphur

233

July 2008, Thailand

Table 5: Mechanical properties of para-rubber plate with
Carbon Black and CaCO3.
Carbonblack:
CaCO3

Compressionset (%)

60N:0C
60N:50C
80N:50C
100N:50C

63
74
46
54

Mechanical Properties
TensileStrainHardness
strength(%)(Shore D)
(MPa)
14
404
60
13
451
66
12
327
72
10
219
77

Tear
strength(N/mm)
60
53
33
25

From Table 5 and focusing on formulae 60N:0C and 60N:50C, it isfound that CaCO3 makes higher in compression set, strain and hardness.
However the tear and tensile strengths are a little bit decreased. By
considering formulae 60N:50C, 80N:50C and 100N:50C, the compressionset, tensile strength, strain and tear strength are inversely proportional toamount of carbon black. In contrast with the hardness, it is proportional toamount of carbon black.
Normally, the content of carbon black should not excess 60 phr(Chuayjuljit ,Bangkok, 2005) but our main objective is to find the formulathat gives the maximum hardness. Then in this study, we extend the range ofcarbon black to 100 phr. The results of formula 100N:50C indicate that thehardness reaches the highest value but the other properties are lowest. These
results from lose of dispersion and distribution of carbon black’s particles,
and then rubber cannot bind the filters effectively (Chuayjuljit, 2005) andleads to low values in many properties. While many properties have low
values when using carbon black 100 phr but the hardness gives the highest
value since higher density of the para-rubber plate.

Compressive Strengths (ksc)

The results of compressive strength of concrete capping with pararubber plate and steel case are compared to that with sulphur and shown in
Figure 4.

400
300
200
100
0
60N: 0C 60N: 50C 80N: 50C 100N: 50C Sulphur

Capping
Figure 4: Compressive strengths of concrete capping with various formulaeof para-rubber plate and sulphur.

234

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

From Figure 4, it reveals that the using of CaCO3 can reduce not only
the cost of para-rubber plate but also give the higher value of compressive
strength (for case 100N:50C). Thus the suitable formula from this research
is 100N:50C. With this formula, we obtain the compressive strength higher
than capping with sulphur around 7%. The lower compressive strengths, indescending order, are 80N:50C, 60N:50C and 60N:0C.

4. CONCLUSION
From the testing, we found that the most suitable formula of para-rubber
plate is 100N:50C. At this formula, the compressive strength is in good
agreement with those from sulphur capping (larger than sulphur capping
around 7%). In view of cost, the cost of para-rubber plate from this research
is not over than 50 baths/sheet. In comparison with para-rubber plates that
produce at aboard and in the country, the costs of these para-rubber plates
are 500-800 baths/sheet and 180 baths/sheet respectively. Thus the proposed
formula of para-rubber plate has the potential in developing into large scaleof economic.

5. SUGGESTIONS
The results from this formula should be compared with the para-rubber platefrom aboard and in the country.
In order to reduce the cost, the formula should be modified forcapping without steel case.

ACKNOWLEDGMENT
The authors extremely gratitude Thailand Research Fund (TRF) through thesmall rubber project (SPR) grant No.RDG4950125.

REFERENCES
American Society for Testing and Materials, 1996. Annual Book of ASTM
Standards.
ASTM C192/C192 M-00, 2001: Standard Practice for Making and Curing
Concrete Test Specimens in the Laboratory, Annual Book of ASTM
Standards, Volume 04.02.
ASTM C39/C39M-01, 2001: Standard Test Method for Compressive
Strength of Cylindrical Concrete Specimens, Annual Book of ASTM
Standards, Volume 04.02.
ASTM C617-98, 2001: Standard Practice for Capping for cylindrical
Concrete Specimens, Annual Book of ASTM Standards, Volume
04.02.

Study of Properties of Para-Rubber Plates for Using as the Capping on Concrete Specimens forCompression Test instead of Molten Sulphur

235

July 2008, Thailand

J.S. Grygiell, and D.E. Amsler, 1977. Capping concrete cylinders withneoprene pads. Research Report, New York State Department ofTransportation, Albany. No.46.
M. Anusiri, 2006. The applications of bagasse paper for replacing sulphur incapping cylindrical concrete head, NCCE 11, Phuket.
Method of Making Test Cube from Fresh Concrete, 1983. British Standard
Institute, BS 1881: Part 108.
N. Na-Ranong, 2001. Testing for mechanical properties of rubber, Rubber
Technology Division, Rubber Research Institute, Department ofAgriculture, Bangkok, 2001.
P.M. Carrasquillo, and R.L. Carrasquillo, 1988. Effect of using unboundedcapping systems on the compressive strength of concrete cylinders.
ACI Materials Journal, vol. 85, no. 3, pp. 141-147.
P. Khamput and A. Boksuwan, 2006. A study of compressive strength of
concrete capping with Neoprene. Technology and Innovation forsustainable development Conference, Khon Kaen.
P. Sae-Oui, 2004. Rubber: types, properties and usage, MTEC,
Prathumthani.
S. Chuayjuljit, 2005. Rubber Technology, Department of Science,
Chulalongkorn University, Bangkok.

236

Joint Student Seminar on Civil Infrastructures

PARTICLE ASSOCIATED DISCHARGE
OF PATHOGEN INDICATOR ORGANISMSFROM DIFFUSE SOURCES IN
AGRICULTURAL-FORESTRY
WATERSHEDSKYUNGMIN HAN and GEONHA KIM
Department of Civil and Environmental Engineering,
Hannam University Ojungdong 133, Daedukku,
Daejeon, Republic of Korea, 306-791
kimgh@hnu.kr
ABSTRACT
Many concerns have recently been raised about the pathogens insurface water originating from diffuse pollution. It is well known that die off
rate of the pathogens could be very slow when pathogens are associated withsuspended solids. This study aims to understand the pathogen levels andtheir affecting factors to alleviate loadings to a receiving water body. Forty
rainfall events were monitored for their runoff quality at four watersheds
mainly composed of agricultural and forestry land. Ascetically taken water
samples were analyzed in the laboratory for their pathogen indicatororganism levels and chemical characteristics. From the correlation analysis
between suspended solid and pathogen indicator organisms, it could beunderstood that pathogen indicator organism levels has highly related withsuspended solid and flow rate. It could be suggested that large amount ofpathogens can be removed from rainfall runoff by removing of suspended
solid from the raw water.

1. INTRODUCTION
Many concerns are raised about the fecal contamination originated fromrainfall runoffs recently (Conboy and Goss, 2000), since pathogens
originated from fecal directly impact on the human health (US. EPA, 1993).
The pathogen levels of water can be assessed by measuring the indicatororganism population in the water. The indicator organism should: i) be
easily detected using simple laboratory tests; ii) generally not be present in
unpolluted water; iii) be present in concentrations that can be correlatedwith the extent of contamination; iv) have a die-off rate that is not fasterthan the die-off rate for the pathogens under consideration (U.S. EPA, 2001;
Thomann and Mueller, 1987).
Total coliform, fecal coliform, fecal streptococci, and Escherchia coli
are common indicator organisms to be monitored. Diffuse sources of fecal
contaminations are numerous. Illicit sewage connections, wildlife, septic

237

July 2008, Thailand

systems, livestock, landfills, and pastures would be the potential sources.
Storm water runoff can transport significant loads of pathogens fromlivestock pastures, livestock and poultry feeding facilities, and feedlots.
Indicator organisms are often used as a tool to identify the contaminantsources as well. Maul and Cooper (2000) used enterococci and fecal
coliform bacteria concentration to assess the variability of water quality of
the agricultural field during wet weather. Whitlock et al. (2002) used fecal
coliform to identify the sources in an urban watershed.
UNEP and WHO established water quality criteria of coliform
concentration for primary contact recreation purpose. Fecal coliform
concentration from a geometric mean of at least 5 samples should be lessthan 100/100ml for 50% and less than 1000/100ml for 90%. US EPA
restricts E. coli density less than 126/100ml for fresh water for logarithmic
average for a period of 30 days of at least five samples (WHO, 1999).
The Korean Government regulates coliform concentration of surface waterby the fundamental environmental law. Table 1 shows the environmental
criteria for river water quality in Korea.
Table 1: Environmental criteria of Korea for the surface water quality
Class

Water UsepH

BOD
(mg/l)

SS(mg/l)

DO(mg/l)

Coliform(MPN/100ml)

I

Source water class 1
Nature Env. Conserv.

6.5-8.5

≤1

≤ 25

≥ 7.5

≤ 50

II

Source water class 2
Swimming

6.5-8.5

≤3

≤ 25

≥5

≤ 1,000

III

Source water class 3
Indust. use cls. 1

6.5-8.5

≤6

≤ 25

≥5

≤ 5,000

IV

Indust. use class 2
Agricultural use

6.0-8.5

≤8

≤ 100

≥2

--

VI

Indust. use class 3
Life Env. Conserv.

6.0-8.5

≤ 10

--

≥2

--

pH, Biological Oxygen Demand (BOD), Suspended Solid (SS),
Dissolved Oxygen (DO) and coliform concentration are regulated by
the law. Class 2 in the table is for the second class of the source water use,and swimming use of the water. To meet the second class of water quality,
pH should be in the range of 6.5 and 8.5, BOD should be less than 3 mg/L,
SS should be less than 25 mg/L, DO should be larger than 5mg/L, andcoliform concentration should be less than 1,000 MPN/100 ml. Among 5
constituents, however, only a criteria for BOD concentration is considered
for the water resource planning purposes in the practice. This is possibly
due to insensitiveness of the parameter range between classes such as pH,
SS, and DO, lack of existing data for coliform concentration. In addition,
BOD is well-known parameter to the public including Non-Government

238

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Organizations. Even though BOD is now emphasized for regulation
purpose, understanding fecal contamination is of importance for protecting
public health.
Usually high uncertainty is associated with fecal
contamination in water quality analysis and data interpretation. If we
suppose the main objectives of water resource planning is “to provide
healthy water to the public”, the importance of coliform concentration in thesurface water is clear.
The research objectives of this study were: i) to present pathogen
indicator organism level of rainfall runoff; ii) to study the relationshipbetween indicator organism concentration and suspended solid; and iii) tostudy the possibility of pathogen removal from rainfall runoff by removing
suspended solid from water.

2. MATERIALS AND METHODS
Four watersheds of areas between 2.85 km2 and 27.37 km2 were selected formonitoring rainfall runoff. Accessibility, safety issues of field workers,
representative land use, and ease of sampling were major factors consideredin selecting the study watersheds. Study watersheds are located in theGeum River basin, one of the four major river basins in the Republic ofKorea. The length of the river is 401.4 km, and the river basin covers 988.5
km2.
Table 2 is the summary of topography variables and land use
description of the four study watersheds. Ten rainfall events were monitored
at each study watershed, mostly during March to September, 2002. Rainfall
events to monitor were selected among several rainfall events considering
field worker’s safety and data quality. Runoff volumes were measured
using a velocity meter probe, Global Water® FP-101 of Plano Molding
Company, USA. Water samples were taken manually and some byautomatic samplers to minimize sampling errors. About 150 samples of theconcentration data were obtained for each study watershed, andapproximately, fifteen samples were taken for each rainfall event. Quantityand quality of the low flow were monitored two times a week at each site
as well.
At the six monitoring stations in the Geum River, water samples weretaken on a weekly basis during drought season from October, 2002 to April,
2003. The monitoring stations located 10 km apart, respectively, along theriver. Flow rate of the monitoring points were estimated using the rating
curves provided by the Korea Water Resources Corporation. Averageannual rainfall depth at the Geum River Basin is 1,279 mm.
All samples were analyzed within 8 hours after collection. Suspended
solid concentrations were measured by using the Standard Methods 20th ed.
For the microbial analysis, aseptic water samples were taken in a sterilized,
separate container. Water samples were brought to the laboratory
refrigerated and analyzed using aseptic techniques. Total coliform (TC) andParticle Associated Discharge of Pathogen Indicator Organisms from Diffuse Sources in AgriculturalForestry Watersheds

239

July 2008, Thailand

E. coli (EC) concentrations were analyzed using Petrifilm™, from 3M
Corporation. Petrifilm™ is a variation of the heterotrophic plate countmethod and thus enumeration is expressed as Colony Forming Units(CFU/100 ml). The technique is effective for low-to-medium concentration
samples and is also inexpensive (Lisle, 1993).
SPSS ver. 10.0 was used to compute the descriptive statistics and thePearson correlation matrices. Skewed data were log transformed for further
analysis.
Table 2: Topography and land use description of the study watersheds
Lengtha

(Km2)

(Km)

1

3.38

2.875

62.61

1356.7

2

2.85

1.575

22.64

1252.1

3

4.97

1.649

41.17

1252.1

4

27.37

6.173

5.97

1356.7

Watershed

a
b

Mean

Area

slope
(%)

RAINavebLand use(mm)(%)
forest 99.5, road 0.1,
others 0.4
rice paddy 1.8, cropland 0.7,
forest 94.2, road 0.7, others 2.6
rice paddy 8.4, cropland 6.4,
forest 82.3, road 1.4
rice paddy 35.9, forest 44.8,
residential 13.3, others 6.0

channel length
average annual precipitation depth

3. RESULTS AND DISCUSSION
Figure 1 shows the hydrograph and time series variation of SS and TC
concentrations for runoff of fourth rainfall event at watershed 4. It can beseen from the figure that SS concentration follows the shape of hydrograph.
Table 3 is the descriptive statistics of runoff concentration of
constituents by study watersheds. The maximum average SS value 116.4
mg/L was given by watershed 3, followed by watershed 4, watershed 2, andwatershed 1. The magnitude of standard deviation and standard error werein the same order. In Table 1, watershed 4 showed the highest ratio ofagricultural land use to total area and the lowest mean slope among the 4watersheds. Maul and Cooper (2001) reported that runoff quality varied
greatly within agricultural sites, indicating that the responses of some
agricultural fields are different from those of others in terms of SS, andmaybe related to watershed characteristics other than land uses. As SS canbe removed from water by settling, flow velocity may affect SS
concentration. Average concentration of pathogen indicator showing

240

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Flow rate (m3/hr)increasing tendency as the proportion of agricultural increased such as TC
and EC.
8000
6000
4000
2000
0

10

20

30

20

30

Time (hr)(a) Hydrograph

SS (mg/L)

160
110
60
10
0

10
Time (hr)TC (numbers/100mL(b) Suspend solid concentration variation as a function of time
80000
60000
40000
20000
0
0

10

20

30

Time (hr)(c) Total coliform concentration variation as a function of time
Figure 1: Hydrograph and time series variations of contaminantconcentrations of rainfall runoff for fourth rainfall event at watershed 4

Particle Associated Discharge of Pathogen Indicator Organisms from Diffuse Sources in AgriculturalForestry Watersheds

241

July 2008, Thailand

Table 3: Descriptive statistics of runoff concentration for study watersheds
SS

TC

EC

Watershed
1
2
3
4
Averagec
1
2
3
4
Average
1
2
3
4
Average

na
147
150
149
143
147
150
149
143
147
150
149
143

Averageb
2.1
60.8
116.4
86.2
66.4
4225
1759
15750
30250
16863
156
3875
3392
11278
4622

SDd
10.0
180.4
398.1
294.0

SEe
0.8
14.7
32.6
24.6

6211
15883
13479
25187

512
1297
1104
2106

0
0
200
400

32000
58000
50000
146000

389
7480
5655
12952

32
611
463
1083

0
0
0
0

3200
40000
42000
70500

Minimum Maximum
0
112.3
0.3
1425.00.3
3510.02.52612.0anumber of samples taken at the designated watershed.
average for the designated watershed.
caverage for all four study watershed.
dstandard deviation.
estandard error.
b

Table 4 is the Pearson coefficients from the correlation analysis of
between EMCs of SS, TC, and EC. Pearson correlation coefficient ranges
between −1∼ +1. Complete correlation shows +1, and complete inverse
correlation shows −1.
Table 4: Correlation analysis result between suspended solid and coliforms
SS

TC

EC

SS

1.00

0.408**

0.380**

TC

0.408**

1.00

0.523**

EC

0.380**

0.523**

1.00

Figure 2 is the time series variation of rainfall depth, flow rate,
concentration of suspended solids, biological oxygen demand, total coliform
and fecal coliform at monitoring station R5 from January, 2001 to February,
2003. Data were obtained from concentration database of the automatic
monitoring network of the Korean Ministry of Environment. The
monitoring station is located at the vicinity of Gongju city. This point was
selected because large discrepancies occur between measured water quality
data and predictions made by the water quality model, QUAL2E, carried out
by the authors. These errors were caused mainly due to the inaccurate
non-point source pollution loading data input. As the concentration of fecal

242

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

coliform was measured by the multiple fermentation technique in the unitof MPN/100 ml, the concentration shows 6 to 20 times higher compared tothe concentration measured by the heterogeneous plate count method as
done in the research.
From Figure 2, it can be seen that the shape of pollutographs follows
the shape of the hydrograph except BOD. As suspended solid and coliform
concentration dynamics are highly related with the flow rate, correlation
analysis between flow rates and concentration were carried out. Table 5.
is the Pearson correlation coefficients between water level and water quality
concentrations (number of data = 144). The Pearson coefficient between
flow rate and BOD is -0.36, indicates weak inverse correlation. Suspended
solid concentration showed weak correlation with flow rate (0.375), same as
fecal coliform (0.018). The Pearson coefficient for flow rate against total
coliform was 0.71 and significant at 0.01 level. High correlations between
flow rate and coliforms were occurred because the majority of
microorganisms attached on sediment (Borst and Selvakumar, 2003) can betransported to downstream when high mobility occurs during wet
weather. Even though most of coliform bacteria decayed as soon as theyleft their host, organisms attached on sediment remain active up to months,
depending on the nature of the soil, temperature, pH, moisture, andmicroflora (Howell et al., 1996). These organisms may be re-suspended
when high flow condition arises.
It is noticeable that coliform
concentrations are more related with flow rate that BOD concentration.

Particle Associated Discharge of Pathogen Indicator Organisms from Diffuse Sources in AgriculturalForestry Watersheds

243

July 2008, Thailand

Figure 2: Precipitation depth, suspended solid, BOD, total coliform, andfecal coliform variations of the Geum River.
Table 5: Pearson correlation coefficients between water level and water
quality concentrations
Level
Level
BOD
COD
SS
TC
FC

-.363
-.252
.375
.712**
.018

BOD
-.363
.621**.130-.515**
.023

COD
-.252
.621**
.288
-.385
-.116

SS
.375
.130
.288
.192
.534**

TC.712**-.515**
-.385
.192

FC
.018
.023
-.116
.534**.134.134** Correlation is significant at the 0.01 level (2-tailed).

4. SUMMARY AND CONCLUSIONS
The main objectives of this study were to understand impacts of topography
and land use on rainfall runoff water quality in watersheds mainly consistingof forestry and agricultural land use. Forty rainfall events were monitored
for organics and nutrients at four study watersheds. The ratio of agriculturalland use to the total area of study watersheds were in the range of 0.01 to
0.36.
This study aimed to characterize the coliform concentrations of theGeum River, Korea and to understand the relationship between flow rateand coliform concentrations. Rainfall runoff is one of the main diffuse
pollution sources to degrade the surface water in microbial aspect. From thewater quality monitoring of the river, it can be seen that rainfall runoff froma watershed with more agricultural activities showed higher coliform
concentrations. The correlation analysis between the indicator organisms,
suspended solid, and flow rate of the river revealed that the total coliform
concentration was highly correlated with the flow rate while BOD
concentration has a weak inverse correlation with the flow rate. Highcorrelations between flow rate and coliforms were occurred because themajority of microorganisms attached on sediment, and can be transported todownstream when high mobility occurs during wet weather.

ACKNOWLEDGEMENT
This research was supported by a grant (code # 1-5-1) from the Sustainable
Water Resources Research Center of the 21st Century Frontier Research
Program, Korean Ministry of Science and Technology Please place tables intheir intended location in the text (Table 1).

REFERENCES

244

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Conboy M.J. and Goss M.J., 2000. Natural protection of groundwater
against bacteria of fecal origin. J. of Contaminant Hydrology,
43(2000), 1-24.
Lisle J., 1993. An operator’s guide to bacteriological testing, American
Water Works Association, Denver, CO, USA.
Maul, J.D., Cooper, C.M., 2000. Water quality of seasonally flooded
agricultural fields in Mississipi. USA. Agriculture Ecosystems &Environment. 81(2000), 171-178.
Thomann R.V. and Mueller J.A., 1987. Principle of Surface Water Quality
Modeling and Control, Harper & Row, New York, NY.
U.S. Environmental Protection Agency, 1993. Preventing waterborne
disease. EPA/640/K-93/001, United States Environmental Agency,
Washington DC, USA.
U.S.Environmental Protection Agency, 2001. Protocol for developing1
pathogen TMDLs. EPA 841-R-00-002. Office of Water (4503F).
Washington, DC., United States Environmental Protection Agency.
Whitlock J.E., Jones D.T. and Harwood V.J., 2002. Identification of sourcesof fecal coliforms in an urban watershed using antibiotic resistanceanalysis. Water Research, 36(2002), 4273-4282.
World Health Organization., 1999. Health-based monitoring of recreational
waters: the feasibility of new approach (The ‘Annapolis protocol’),
WHO/SDE/WSH/99.1, World Health Organization, Geneva.

Particle Associated Discharge of Pathogen Indicator Organisms from Diffuse Sources in AgriculturalForestry Watersheds

245

July 2008, Thailand

246

Joint Student Seminar on Civil Infrastructures

PHYSICAL PROPERTIES OF GROUTFOR CLOSE-LOOP VERTICAL GROUNDHEAT EXCHANGERCHULHO LEE, HUJEONG GIL and HANGSEOK CHOI
Department of Civil, Environmental and Architectural Engineering,
Korea University, 5-ga, Anam-dong Seongbuk-gu, Seoul 136-701, Korea
cryfreer@korea.ac.kr
ABSTRACT
Thermo-mechanical properties of grout materials have been
investigated, which are used for backfilling a ground heat exchanger in thegeothermal heat pump (GHP) system. The thermal conductivity andviscosity of nine different bentonite grouts and a cementitious grout withvarious mix proportions have been considered in this study. The bentonite
grouts indicate that the thermal conductivity and viscosity increase with thecontent of bentonite or filler (silica sand). In addition, material segregation
can be observed when the viscosity of grout is relatively low. The saturated
cement grouts appear to possess much higher thermal conductivity than thesaturated bentonite grouts, and the reduction of thermal conductivity by
drying the cementitious grout is less than the case of the bentonite grouts.
Maintaining the moisture content of grouts is a crucial factor in enhancing
the efficiency of ground heat exchangers.

1. INTRODUCTION
The efficiency of heat exchange in a close-loop vertical ground heatexchanger is one of the most crucial factors to enhance the geothermal heatpump (GHP) system. Influence factors on heat exchange can be the thermal
conductivity of backfilling grout and HDPE pipes, heat interference
between the pipes, the thermal conductivity of adjacent geologic formations.
In this paper, thermo-mechanical properties of grout materials, i.e., thermal
conductivity and viscosity, have been investigated, which are used forbackfilling the ground heat exchanger. The backfilling grout should be used
not only to seal the annulus between the borehole and heat exchanger loop
but also to exchange properly heat between the ground formation and theloop.
Increase in the thermal conductivity of backfilling grouts leads toconsiderable reduction in installation cost for ground heat exchanger by
shortening the required bore length. In addition, acceptable groutability ofgrouts should be guaranteed during the installation of the heat exchanger inorder to fill completely the annulus without any gaps that may cause thermal
discontinuity.

247

July 2008, Thailand

The thermal conductivity and viscosity of nine different bentonite
grouts from different producers have been experimentally evaluated in caseof both neat bentonite grouts and thermally enhanced bentonite grouts withaddition of silica sand as a filler. In addition, a phenomenon of material
segregation was observed when the viscosity of the thermally enhanced
bentonite grout was low.
Cementitious grouts as an alternative grout material (Allan, 2000;
Allan and Philippacopoulos, 2000) with various mix proportions have been
considered in this study. Allan and Philippacopoulos (1999, 2000) reported
a series of experimental results on the thermal conductivity of cementitious
grouts and proposed an optimized cementitious grout formulation, namely
Mix 111, which enhances thermal conductivity. The cementitious grouts are
relatively inexpensive, safe and easy to work. The thermal conductivity andviscosity of cementitious grout have been investigated and compared to thethermo-mechanical properties of bentonite grouts.

2. MATERIALS
Nine bentonite grouts provided by three different producers in Korea havebeen chosen for this study. The fundamental properties of each grout aresummarized in Table 1. Bentonite 1 is a low grade bentonite used for a
casting process, and Bentonite 2 is improved by adding montmorillonite toincrease swelling potential. Bentonite 3, 4, and 5 are produced for the
purpose of civil engineering construction such as a mixture for a landfill
liner or bentonite slurry. Especially, Bentonite 5 possesses very highviscosity and swelling potential but is more expensive than the other grouts.
Bentonite 6 is used in constructing a landfill liner. Bentonite 7 is a granular
product and used in waterproofing. On the contrary, Bentonite 8 is
powdered and produced for geothermal application. In particular, Bentonite
9 includes silica sand to an extent during manufacturing process to enhance
the thermal conductivity. Silica sand was used as a filler of which gradation
curve is shown in Figure 1.
Considering the cementitious grout, potland cement was selected as amain grouting material with mixture of the silica sand used in the bentonite
grout as a filler, and a small amount of bentonite was added for preventing
the bleeding or segregation of the cementitious grout.

248

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Table 1: Fundamental physical properties of bentonites
Bentonite

Producer

1
2
3
4
5
6
7
8
9

D
D
S
S
S
C
C
C
C

Water
Content
(%)
10.0
10.0
8.9
9.5
9.5
12.0
12.0
12.0
12.0

Swelling
Index(ml/2g)
12-15
24-30
15.0
23.0
24.5
18.0
29.0
10.0
11.0

pH
9-11
9-11
10.0
10.1
10.0
6-12
6-12
6-12
6-12

100

Percent finer(%) .

90
80
70
60

D10 = 0.0750

D30 = 0.154030

D60 = 0.3

20

Cu = 4.23

10

Cc = 1.071

0
0

1

100

Grain size(mm)Figure 1: Gradation curve of silica sand.

3. EXPERIMENTAL
3.1 Thermal conductivity
The thermal conductivity of grouts was measured using QTM-500K
thermal conductivity meter (Kyoto Electronics) which is equipped with PD13 probe of which dimension is 95 mm × 40 mm. The equipment adopts thetransient hot wire method to measure the thermal conductivity of grout
material.
Because the bentonite grout paste is amorphous, an acrylic container
box was devised to fill the paste in it and to permit the measurement ofthermal conductivity. The container box consists of a water jacket, aperimeter passage, which is connected to a water tank to flow water ofcontrolled temperature through it, and thus a room temperature of 20°C is
presumably maintained in bentonite grout specimens during measuring
thermal conductivity.
After curing the cementitious grouts in a rectangular mold for 14 days,
the thermal conductivity of both the wet and air-dried specimens were
measured using the QTM-500K thermal conductivity meter.

Physical Properties of Grout for Close-loop Vertical Ground Heat Exchanger

249

July 2008, Thailand

3.2 Viscosity
The viscosity of bentonite grouts was measured by a vibration-type
viscometer of which measuring plate vibrates with a frequency of 30 Hz.
The viscosity range measurable in the viscometer is from 0.003 to 120 P. In
order to investigate the isothermal change in viscosity with time after
mixing bentonite grouts, a similar acrylic container box to that used formeasuring thermal conductivity was devised, which is also equipped with awater jacket to flow water at a room temperature of 20°C.
Viscosity of cementitious grout paste was indirectly estimated byflowability. It is measured by both the V-Funnel test and the slump flow test.

4. RESULTS
4.1 Bentonite grout

Thermal conductivity (W/m℃)
ㄴ.

When bentonite is used for backfilling the ground heat exchanger,
15% to 25% bentonite by weight is usually mixed with water. Therefore,
two mix proportions of 20% and 30% bentonite by weight were chosen toinvestigate the thermal conductivity of the nine neat bentonite grouts withno addition of fillers. Figure 2 compares the measured thermal conductivityof each neat bentonite grout in the fully saturated condition. In case of 20%
bentonite by weight, the thermal conductivity lies in a narrow range of 0.740.81 W/m°C. For 30% bentonite case, the range of thermal conductivity is
0.76-0.95 W/m°C.
1.2
30% Bentonite
20% Bentonite
1

0.95
0.83

0.85

0.88
0.81

0.76

0.80

0.81

0.75

0.74

0.77

0.79

0.78

0.76

4

5

6

7

8

9

0.8
0.76

0.77

0.81

1

2

3

0.84

0.6

0.4

Bentonite grouts

Figure 2: Thermal conductivity of neat bentonite grouts
After air-drying the specimens for 10 days, the thermal conductivityof the dried bentonite grout was measured to show how much thermal
conductivity decreases by drying process, which may represent a situationof groundwater table drawdown. In the case of 30% bentonite, the thermal
conductivities of Bentonite 1 and 2 were substantially reduced from 0.83 to
0.27 W/m°C and from 0.85 to 0.31 W/m°C, respectively. Note thatmaintaining bentonite grout saturated should be required to avoid

250

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

unpredictable reduction of heat conduction performance of undergroundheat exchangers.
The thermal conductivity of bentonite grouts can be enhanced by theaddition of a small amount of fillers such as silica sand (Han et al., 2005).
For the two cases of bentonite content (20% and 30%), the improvement ofthermal conductivity by the addition of silica sand was investigated. The
amount of added silica sand was 15, 30, 45, and 60% of bentonite by weight.
Figure 3 shows the variation of thermal conductivity for the case of 20%
bentonite. At each 15% increase of silica sand content, the thermal
conductivity increased by 0.08-0.12 W/m°C on the average. A similartendency can be observed for the case of bentonite content 30% as shown in
Figure 4. The result indicates that the increase in the thermal conductivity
due to the addition of silica sand is not significant, and even the case of 60%
of silica sand results in the thermal conductivity less than 1.4 W/m°C.

Thermal conductivity (W/m℃)
s .

1.4

1.2

1

Bentonite 1
Bentonite 2
Bentonite 3
Bentonite 4
Bentonite 5
Bentonite 6
Bentonite 7
Bentonite 8
Bentonite 9

0.8

0.6

0.4

0

15

30

45

60

Silica sand content (%)

Figure 3: Thermal conductivity of 20% bentonite grout with various
contents of silica sand

Thermal conductivity (W/m℃)
s .

1.4

1.2

1

Bentonite 1
Bentonite 2
Bentonite 3
Bentonite 4
Bentonite 5
Bentonite 6
Bentonite 7
Bentonite 8
Bentonite 9

0.8

0.6

0.4
0

15

30

45

60

Silica sand content (%)

Figure 4: Thermal conductivity of 30% bentonite grout with various
contents of silica sandPhysical Properties of Grout for Close-loop Vertical Ground Heat Exchanger

251July 2008, Thailand

In case of the 20% bentonite in Figure 3, the thermal conductivity of
Bentonite 1 increases to a maximum value at the silica sand content of 30%
and then is kept to the value. The reason for this can be explained by aphenomenon of material segregation. Bentonite 1 possessed the lowest
viscosity at the same bentonite content compared to the other bentonite
grouts, and thus the silica sand mixed in the Bentonite 1 grout paste settled
down and separated from the bentonite paste. Settled silica sands wereobserved at the bottom of the container as shown in Figure 5.

Figure 5: Settled silica sand at the bottom of container
The viscosity of bentonite grouts after being mixed with water should
increase with time due to the rheological characteristic (Choi et al., 2008). A
considerable increase in viscosity can make pumping grout difficult during
installing ground heat exchangers. In this paper, a change in viscosity withtime has been quantitatively investigated for two bentonite grouts, Bentonite
1 and 3, with the bentonite content of 20%. In this comparison, the effect ofmagnitude of mixed silica sand was also examined. Figure 6 shows thesignificant increase in viscosity with time for 6 hours. In addition, the rate ofviscosity increase becomes greater when the amount of silica sand mixed in
the grout increases. Especially, the viscosity of Bentonite 3 mixed with 60%
of silica sand reaches the measurement limitation of the viscometer (i.e.,
120 P). Therefore, care must be taken not to delay significantly grout
pumping operation after preparing the grout paste in the field.
60%

40

Viscosity (P) .

35

45%

30

30%

25
20

15%

15

0%

10
5
0

0

1

2

3

4

6

Time (hr)(a) Bentonite 1 (20%)

252

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

140

60%

Viscosity (P) .

120
100

45%
30%
15%

80
60

0%

40
20
0

0

1

2

3

4

6

Time (hr)(b) Bentonite 3 (20%)
Figure 6: Comparison of increase in viscosity with time
4.2 Cementitious grout
Allan and Philippacopoulos (1999, 2000) reported from a series oflaboratory tests that the thermal conductivity of neat cement grout ranged
from 0.80 to 0.87 W/m°C. In addition, an optimized grout formulation,
namely Mix 111, yielded the thermal conductivity of up to 2.42 W/m°C.
The grout consists of cement, water, a particular grade of silica sand,superplasticizer, and a small amount of bentonite.
In this paper, the role of influence factors such as water/cement ratio,
silica sand/cement ratio, and bentonite dosage on the thermal conductivity
and viscosity of cementitious grouts has been investigated. The
experimental results are as follows:
4.2.1 Water/cement ratio
Five different mix proportions for neat cement were prepared by only
varying the water/cement ratio as 0.4, 0.5, 0.6, 0.7, and 0.8, as shown in
Table 2 and thermal conductivity and viscosity with time were measured on
the specimens. The measured thermal conductivity and slump flow for thefive mix proportions are described in Figure 7. Increasing the water/cement
ratio leads to a decrease in thermal conductivity and an increase in slump
flow which means the enhancement of flowability. The thermal conductivity
decreases by 0.01 - 0.07 W/m°C with the increment of water/cement ratio of
0.1. When the specimens were air-dried, the thermal conductivity was
reduced only by around 0.25 W/m°C. This reduction is far smaller than thecase of bentonite grouts, and thus the cementitious grout may be lessvulnerable to a drying condition due to water table drawdown.
Allan and Philippacopoulos (1999) reported that it is important tomaintain a minimized water/cement ratio for increasing thermal
conductivity and decreasing hydraulic conductivity. However, when it
comes to groutability or pumpability, very small values of water/cement
ratio with high viscosity can result in difficulty of pumping cementitious
grout into the borehole. Accordingly, it is necessary to consider not only

Physical Properties of Grout for Close-loop Vertical Ground Heat Exchanger

253

July 2008, Thailand

thermal conductivity but also viscosity in order to determine an optimized
mix proportion for cementitious grouts.
Table 2: Effect of water/cement ratio and viscosity
CementGeo-1 Geo-2 Geo-3 Geo-4 Geo-5
0.40
0.50
0.60
0.70
0.80
w/c ratio
Slump Flow(mm) 164-168 220-231 284-288 350-355 355-385
5.6
2.1
<1
<1
<1
V-Funnel(sec)400saturated
2

350

dry
slump flow

300
250

1.5
1.20

1.16

1.15

1.13

1.06

1

200
150

0.96

0.89

0.92

0.86

0.79

100

Slump Flow(mm) ㄴ

Thermal conductivity (W/m℃)
ㄴ

2.5

0.5
50
0

0
Geo-1

Geo-2

Geo-3

Geo-4

Geo-5

SampleFigure 7: Thermal conductivity and slump flow with varying
water/cement ratio
4.2.2 Silica sand/cement ratio
Five different mix proportions with the water/cement ratio of 0.6 wereconsidered with varying the silica sand/cement ratio as 2.0, 2.2, 2.4, 2.6, and2.8, as shown in Table 3. In this case, a small dosage of superplasticizer isadded to the mixture by 0.1% of cement weight to maintain proper
groutability. The measured thermal conductivity and slump flow for the fivemix proportions are described in Figure 8. Increasing the silica sand/cement
ratio leads to an increase in thermal conductivity and a reduction in slump
flow which decreases groutability. The thermal conductivity increases by
0.01 - 0.09 W/m°C with the increment of silica sand/cement ratio of 0.2.
When the specimens were air-dried, the thermal conductivity was reduced
by around 0.20 – 0.42 W/m°C that is far smaller than the case of bentonite
grouts, and thus the cementitious grout mixed with silica sand may be lessvulnerable than bentonite grout to a drying condition.
Allan and Philippacopoulos (1999) added a superplasticizer of about
8.8 litres per a unit volume (1 m3) of cementitious grout to assure suitable
groutability. However, properties of superplasticizer should be different foreach product, and it is difficult to characterize quantitatively the role ofsuperplasticizer in cementitious grout mixed with silica sand.

254

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Table 3: Effect of silica sand/cement ratio and viscosity
Geo-6
0.60

Geo-7
0.60

Geo-8
0.60

Geo-9
0.60

Geo-10
0.60

2.00

2.20

2.40

2.60

2.80

195-210180-187

107-110

100

100

2.5

2.6

4.5

300

300

400

Thermal conductivity (W/m℃)
ㄴ

3

2.5
2.21
2

2.28

2.34

2.43

1.99

2.01

2.44

300
2.08

1.91

2.11

250
200

1.5

150

1

100

saturated
0.5

350

dry

Slump Flow(mm) ㄴ

Cementw/c ratio
Sand/cement
ratio
Slump
Flow(mm)
V-Funnel(sec)50slump flow
0

0
Geo-6

Geo-7

Geo-8

Geo-9

Geo-10SampleFigure 8: Thermal conductivity and slump flow with varying
silica sand/cement ratio
4.2.3 Bentonite content
Five different bentonite dosages with the water/cement ratio of 0.6
and the silica sand/cement of 2.4 were considered with varying the bentonite
content of 1, 2, 3, 4, and 6% of cement weight as shown in Table 4. Allanand Philippacopoulos (1999) noted that the purpose of a small dosage of
bentonite added into cementitious grouts was prevention from bleeding andthe segregation of silica sand.
As can be seen in Figure 9, the bentonite content of 1 – 6% of cement
weight does not affect significantly the thermal conductivity of cementitious
grouts. On the contrary, the addition of a small amount of bentonite leads toa considerable reduction in the flowability of the grouts, that is, only 2% ofbentonite made the value of slump flow become the minimum value of 100
mm. When the specimens were air-dried, the thermal conductivity was
reduced by around 0.34 – 0.44 W/m°C that is slightly larger than the case of
no bentonite addition.

Physical Properties of Grout for Close-loop Vertical Ground Heat Exchanger

255

July 2008, Thailand

Table 4: Effect of bentonite addition and viscosity
Cementw/c ratio
Sand/cement ratio
Bentonite/cement ratio
Slump Flow(mm)V-Funnel(sec)Geo-11 Geo-12 Geo-13 Geo-14 Geo-15
0.60
0.60
0.60
0.60
0.60
2.40
2.40
2.40
2.40
2.40
1%
2%
3%
4%
6%
105-107 100
100
100
100
4.5
300
300
300
300

400
350

2.5
2.27

2.30

1.93

1.95

2.29

2.31

2.27
300

2

250

1.97
1.85

1.85

1.5

200
150

1

100
0.5

Slump Flow(mm) ㄴ

Thermal conductivity (W/m℃)
ㄴ3

saturated
50

dryslump flow00
Geo-11

Geo-12

Geo-13

Geo-14

Geo-15

SampleFigure 9: Thermal conductivity and slump flow
with different bentonite content

5. CONCLUSION
The following conclusions are based on the findings for the thermal
conductivity and viscosity of bentonite grouts and cementitious grouts.
1. In case of the nine neat bentonite grouts with no addition of fillers,
two mix proportions of 20% and 30% of bentonite by weight show a rangeof thermal conductivity in the fully saturated condition of 0.74-0.81 W/m°C
and 0.76-0.95 W/m°C, respectively, which are far smaller than the
cementitious grouts. When the specimens are air-dried, the thermal
conductivity significantly decreases. Increase in thermal conductivity due tothe addition of silica sand is not significant, and even the case of 60% of
silica sand results in the thermal conductivity less than 1.4 W/m°C.
2. The viscosity of bentonite grouts significantly increases with time.
The rate of viscosity increase becomes greater when the amount of silica
sand mixed in the grout increases. It is highly recommended to be careful toprepare grout paste with no delay in the field when pumping it into theborehole.
3. For neat cementitious grouts, increasing the water/cement ratio
leads to a decrease in thermal conductivity and an increase in slump flowwhich means the enhancement of flowability. A reduction of thermal

256

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

conductivity due to air-drying is about 0.25 W/m°C which is far smaller
than the case of bentonite grouts, and thus the thermal conductivity of
cementitious grout may be less vulnerable to a drying condition than the
bentonite grouts.
4. Addition of silica sand to cementitious grouts leads to an increase inthermal conductivity and a reduction in slump flow which decreases
groutability. However, addition of a small dosage of bentonite does notaffect significantly the thermal conductivity of cementitious grouts.

ACKNOWLEGEMENT
The writers appreciate the financial support by grant No. 06 constructioncore D04 from KICTEP, The ministry of land, transport and maritime
affairs. The views expressed in this paper are the writers and do not reflect
the views of KICTEP.

REFERENCES
Allan, M. L., 2000. Material characterization of superplasticized cementsand grout. Cement and Concrete Research 30. pp. 937-942.
Allan, M. L., Philippacopoulos, A., 1999. Properties and performance of
cement -based grouts for geothermal heat pump application. FY 1999
Progress Report, BNL 67006, 53pp.
Allan, M. L., Philippacopoulos, A., 2000. Performance characteristics andmodelling of cementitious grouts for geothermal heat pumps.
Proceeding of World Geothermal Congress 2000. 10th June, Beppu
and Morioka, Japan, pp. 3355-3360.
Choi, H., Lee, C., Choi. H-P, and Woo, S-B., 2008. A study on the physicalcharacteristics of grout material fro backfilling ground heat exchanger.
Journal of the Korean Geotechnical Society. 24(1). pp. 37-49.
Han, J., Han, G., Han, H., and Han, C., 2005. Geothermal Heat Pump
(GHP) System. in Korean. Han Lim Won.

Physical Properties of Grout for Close-loop Vertical Ground Heat Exchanger

257

July 2008, Thailand

258

Joint Student Seminar on Civil Infrastructures

ESTIMATION OF ULTRASONICCAVITATION ENERGY IN A LARGE-SCALESONOREACTORYOUNGGYU SON, MYUNGHEE LIM and JEEHYEONG KHIM
Department of Civil, Environmental and Architectural Engineering,
Korea University, 5-ga, Anam-dong Seongbuk-gu, Seoul 136-701, Korea
hyeong@korea.ac.kr
ABSTRACTIn this study, ultrasonic cavitation-energy distributions were analyzed
in a large-scale sonoreactor, using three-dimensional mapping methods.
The highest and most stable cavitation energy state, through the whole
length, was obtained with an ultrasound application of 72 kHz. However,very poor energy distributions were obtained at ultrasound applications of
110 and 170 kHz. In the presence of a reflector, cavitation energy
distribution in the sonoreactor was much dependent on the location of
opposite reflective wall, which determined by wavelength of applied
ultrasound. . Interestingly, in 35 kHz average energies were slightly higher
in the case of 20 cm than in the case of 50 cm although the volume ofsonoreactor in the case of 20 cm was 2.5 times larger than in the case of
50cm.

1. INTRODUCTION
Chemical and mechanical effects caused by ultrasonic cavitation inhomogeneous and heterogeneous systems have been widely studied.1,2) The
important factors that affect cavitation include: ultrasonic frequency;
acoustic power; dissolved gasses; ambient temperature; and ambientpressure, etc.2,3) Most of the previous research concerning the study ofultrasonic reactions was conducted in small-scale sonoreactors and it was
assumed in these studies that the effects of these factors were approximately
the same for every position in the reactors. However, this assumption is not
valid when ultrasonic reactions are conducted in large-scale sonoreactors. In
particular, the distribution of ultrasonic energy attributed to input acoustic
power can change significantly according to the size and shape of thesonoreactors as well as to the location of the transducers. Therefore, thedegree of chemical and mechanical effects in each position becomes uneven.
Several methods have been reported that analyze ultrasonic energy
distribution. These include a hydrophone for the local pressure amplitudes,4)
optical fiber tips for the local pressure amplitudes and aluminium foil
analysis for the mechanical effects,5) and a cavitation activity indicator for
the instantaneous cavitational intensity.6) However, there has not been an

259

July 2008, Thailand

investigation that has focused on measuring ultrasonic energy distribution
for large-scale sonoreactors.
This present study was designed to evaluate the performance of apilot-scale sonoreactor under various ultrasonic frequencies. The specificobjectives of this investigation were to analyze the ultrasonic cavitationenergy in the sonoreactors through three-dimensional cavitation energy
measurements and to understand the effect of a reflector in a large-scalesonoreactor.

2. EXPERIMENTAL PROCEDURE
2.1 Reactor configuration
The pilot-scale sonoreactor used in this study consisted of an acrylic
bath (L 1.20 m × W 0.60 m × H 0.40 m) and an ultrasonic transducer
module (Mirae Ultrasonic Tech.) placed at the center of the side of the bathas shown in Figure 1. The transducer module (L 0.20 m × W 0.20 m × H
0.07 m) contained nine PZT transducers and could produce ultrasound of 35,
72, 110, and 170 kHz frequency. The maximum power of the transducer
module was 400W. Acoustic absorbents made of polyurethane were
equipped on all the sidewalls and the bottom, with the exception of the
sidewall where the module was placed in order to prevent the reflection ofultrasound. The reactor was filled with 250 L of tap water.

Figure 1: Schematic of the pilot-scale sonoreactor and the location of
measurement of cavitation energy (side view)

2.2 Measurement of ultrasonic cavitation energy
A three-dimensional cavitation energy analysis was carried out for thefour frequencies of 35, 72, 110, and 170 kHz, with 160 W input power.
From the transducer module to the end of the reactor, 11 sections weredivided along the length. The dimensions of each section were, L 10 cm ×
W 20 cm × H 20 cm, and 99 points were selected for the measurements ofthe cavitation energy in the whole reactor.
The ultrasonic/megasonic cavitation meter (ppb, pb-502) was used forthe analysis of cavitation energy in the sonoreactor. This instrument could

260

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

detect cavitation, or the collapse of the cavitation bubbles as they implodedon the surface of a probe. It could also display the energy density ofcavitation as a unit of W/cm2. The diameter of the probe was 5 cm.
2.3 Reflector
A reflector was placed at 20 and 50 cm and was moved by λ (wavelength)/4 in order to compare the average cavitation energy in 35 kHz and
240 W. The reflector had two 10 mm thick glass plates with a 10 mm airlayer between the two plates.

3. RESULTS AND DISCUSSION
3.1 The effect of frequency
Figure 2 shows the change of cavitation energy at each section
throughout the whole length. In 110 and 170 kHz, very poor energy values
were obtained in comparison to the cases of 35 and 72 kHz. The average
cavitation energies in the whole reactor were 53.50, 83.87, 6.41, and 0.10 W
for 35, 72, 110, and 170 kHz, respectively. Therefore, it was identified that
110 and 170 kHz of ultrasound would not be applied to the sonoreactor
whose irradiation distance is over several tens centimeters. Meanwhile, 35
and 72 kHz ultrasound were estimated as high applicable wave energies.

Figure 2: Change of cavitation energy at each section throughout thewhole length.
3.2 The effect of reflector
Figure 3 shows the effect of a reflector in the sonoreactor. Average
cavitation energies were significantly dependent on the reflector location,
which was determined by the wavelength of ultrasound. Interestingly, in 35
kHz average energies were slightly higher in the case of 20 cm than in thecase of 50 cm although the volume of sonoreactor in the case of 20 cm was
2.5 times larger than in the case of 50cm.

Estimation of Ultrasonic Cavitation Energy in a Large-scale Sonoreactor

261

July 2008, Thailand(a) 35 kHz, 240W, λ = 4.3 cm(a) 72 kHz, 240W, λ = 2.0 cm
Figure 3: Change of average cavitation energy in the presence of a reflector

4. CONCLUSIONS
Three-dimensional cavitation energy analyses were conducted in a largescale sonoreactor. The following results were found:
1. Various distributions of cavitation energy under different frequency
conditions were measured, even though the experiments were conducted in
the same power intensity.
2. Application of 72 kHz ultrasound showed the most stable andhighest energy distribution in three-dimensional energy analysis.
3. Cavitation energy distribution in the sonoreactor was muchdependent on the location of opposite reflective wall.

ACKNOWLEDGMENTS
This research was supported by a grant (R01-2007-000-20886-0) fromthe Korea Science and Engineering Foundation (KOSEF).

262

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

REFERENCES
Adewuyi, Y. G., 2001. Sonochemistry: Environmental Science andEngineering Applications. Industrial and Engineering Chemistry
Research 40, 4681-4715.
Thompson, L. H. and Doraiswamy, L. K., 1999. Sonochemistry: Scienceand Engineering Industrial and Engineering Chemistry Research 38,
1215-1249
Gogate, P. R., 2007. Application of cavitational reactors for water
disinfection: Current status and path forward. Journal ofEnvironmental Management 85, 801-815.

Estimation of Ultrasonic Cavitation Energy in a Large-scale Sonoreactor

263

July 2008, Thailand

264

Joint Student Seminar on Civil Infrastructures

USE OF SUPERFINE CRUMBRUBBER TO IMPROVE THERMAL &SOUND PROPERTIES OF CONCRETE
PITI SUKONTASUKKUL and SOMYOT WIWATPATTANAPONG
Department of Civil Engineering, Faculty of Engineering
King Mongkut University’s of Technology-North Bangkok
piti@kmutnb.ac.th
ABSTRACT
Abandoned tires are a well recognized environmental problem
worldwide. One way to dispose them is to grind them into crumb rubbers.
Crumb rubber can be used in wide range of applications such as pavement,
blocks, sealant, supplement fuel etc. In Thailand, crumb rubbers areproduced by grinding and can be found in several sizes depending on theapplications (several millimeters to microns). The smallest size that can beachieved is about 500 to 600 micron (0.0197 to 0.0234 in). These superfine
crumb rubbers are used mainly in crack sealant and joint filler applications.
In this study, the superfine crumb rubbers are mixed with concrete byreplacing fine aggregate at the rate of 10%, 20% and 30% by weight. The
role of small particles of crumb rubbers is to act as a filler to fill small voids
in concrete to reduce water absorption and porosity. Also, by replacing highdensity aggregate with low density crumb rubber, the average density ofconcrete is found to decrease. The decrease in density also results in better
thermal and sound properties.

1. INTRODUCTION
1.1 Manufacturing crumb rubber
Around the world, millions ton of tires are being discarded every year.
In Thailand, total consumption of rubber products was about 242 metrictons (533,368 US tons), this number included about 90 metric tons (198,360
US tons) of vehicle tires (2000)(0). In general, the wasted tires are disposedby dumping them on empty lands. But the dumping yards could become fire
hazard and insect or animal habitation (Figure 1). Another way to dispose isby burning, but it causes enormous air pollution and considers irresponsible.
Recently, grinding the discarded tires into small particles (called crumbrubber) presents another solution. Crumb rubber can be used in several
applications such as asphalt, sealants, rubber sheets or mix withcementitious materials like concrete.

265

July 2008, Thailand

Figure 1: Piling yard of abandoned tires in Thailand
In Thailand, the crumb rubbers obtained from reclaiming plants areproduced by grinding which consists of three steps. The first step is to cut
and sort out the grindable parts (parts without radial steels). In the next
process, rubber pieces are fed into the cutting wheel several times until thedesired size is achieved. Finally, crumb rubbers are sorted out according to
the particle size. The grinding technique allows the crumb rubbers to be
produced in various sizes. Size of crumb rubber depend mainly the numberof feeding. At present, about 7 to 8 different sizes of the crumb rubber canbe produced. The biggest one has a diameter of about 5 mm (0.197 in) while
the smallest one has a diameter of about 600 micron (0.0234 in).
1.2 Concrete microstructure
Concrete consists mainly of three components: cement, aggregates andwater. During the mixing, when water comes in contact with cement, seriesof chemical reactions called “hydration reactions” begin. The hydration
reactions are exothermic and involve series of temperature changes frombeginning to end (until concrete get harden).
In harden concrete, the micro structure can be divided into two parts:
1) solid and 2) void (or Porosity) part. The solid part consists of hydrated
cement (Calcium Silicate Hydrate (CSH), Calcium Hydroxide (CH), etc.),
aggregates, unhydrated cement and interface zones between cement andaggregates. As for the porosity, there can be divided into 3 different kinds:
1) capillary pores, 2) gel pores, and 3) interface pores. The pores in concrete
come in various sizes. Capillary pores caused primarily by entrapped waterand are considered the largest of all. Gel pores are consider smallest andcauses by the formation and compaction of CSH(0,0).
Usually, the pore structure plays a significant role on the durability ofconcrete. This is because the existing of these pores allows external
substances (moisture and gas) to migrate in and out of concrete structures.

266

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Some substances can be harmful and caused deterioration in concrete.
Therefore to increase concrete durability, engineers have to deal directlywith the pore structures. Theoretically, the migrations of water and gas
occur mostly through the capillary pores which are large pores and some ofthem might still interconnected(0). To stop the migrations, the volume oflarge sized pores must be reduced. This can be achieved by using small w/c
ratio or using fillers (such as silica fume, fly ash etc.).
1.3 Need for better insulation
Nowadays, the design and construction purposes of a modern house
are not focused on the residential purpose only, but also on energy
conservation and on becoming an integral part of the environment. As weknow, the earth’s average temperature is rising slowly every year due to theeffect of global warming. Cares for the environment are urgently needed by
reducing the use of fuel energy, encouraging the use of recycled materials,
reducing the emission of carbon dioxide gas, etc0). The constructionindustry can help by employing site management to minimize wasted
materials, using recycled aggregates, selecting environmental friendly
materials, etc.
In the case of an individual household, architectural design based on
environmental aspect should be considered in order to achieve such goal.
From a concrete engineer’s point of view, material selection also plays animportant role. The use of better insulating materials can directly reduce
long-term energy consumption.

2. RESEARCH SIGNIFICANCE
In the last 20 years, material properties of crumb rubber concrete have been
investigated quite exclusively0-0. Information on the mechanical propertiesof crumb rubber concrete with particle size varied from 1 mm (0.039 in) andlarger in terms of compressive, tensile, flexural strengths, thermal and sound,is quite well-known. However, information on the effect of crumb rubberwith particle size smaller than 1 mm on properties of concrete is still limited.
With much smaller particle size, some mechanisms may be different fromthose with larger size. For example, the overall absorption of concrete may
be declined due to the decreasing of volume of capillary pores. In addition,
the slump or workability of concrete may be decreased due to the increase in
overall specific surface area.
Therefore, the objective of this study includes;
 Encourage the use of crumb rubber to reduce waste fromabandoned tires.
 Find concrete with better insulation (thermal and sound)properties that can be manufactured easily, cost effective, andenvironmental friendly.

Use of Superfine Crumb Rubber to Improve Thermal & Sound Properties of Concrete267

July 2008, Thailand

Investigation on the effect of superfine crumb rubber on
properties of concrete such as compressive strength, slump,absorption, porosity, thermal and sound properties (such as
thermal conductivity factor, thermal resistivity, heat transfer,sound absorption at different frequencies and noise reduction).

3. EXPERIMENTAL PROCEDURE
3.1 Materials
Materials used in this study consisted of Portland cement type I, 3/8”
(10 mm) coarse aggregate, river sand, crumb rubber (Figure 2), water andsuperplasticizer Type F (13 cc /1 kg (0.36 in3/lb) of cement weight. Crumbrubber with particle size pass through sieve No. 25; the properties andgradation of crumb rubbers are given in Table 1 and Figure 3. The mix
proportion for the control specimen (no crumb rubber) was set at
1.00:0.45:1.64:1.95 (Cement : Water : Fine Aggregate : Coarse Aggregate).
In the case of the superfine crumb rubber concrete (SCRC), fineaggregate were replaced with crumb rubber at 20% and 30% by weight.
Gradation of sand and sand+crumb rubber is given in Figure 4. Details on
the casting and assigned designations are given in Table 2.
Table 1: Properties of crumb rubber
Categories
Average Bulk Specific Gravity (oven dry)Average Bulk Specific Gravity (SSD)
Average Apparent Specific Gravity
Average Absorption (%)
Finess Modulus

No.26
0.61
0.62
0.62
1.05
2.83

Figure 2: Crumb rubber

268

Joint Student Seminar on Civil Infrastructures

ICUS Report 30
100
Percent Finer By Weight

90
80
70
60
50
40
30
20
10
0
1

0.1
0.01
Diameter (in)0.001

Figure 3: Gradation of crumb rubber
100
Percent Finer By Weight90

100% Fine

80
70

70% Fine + 30% CR

60
50
40
80% Fine + 20%
CR

30
20
10
0
1

0.1
0.01
Diameter (in.)

0.001

Figure 4: Gradation of fine aggregate + crumb rubber
Table 2: Details and assigned designations
Weight per m3 (ft3)
Designation
PC
10SCRC
20SCRC
30SCRCw/c

Crumb Rubratio
kg (lb)0.47
00.47
78.4 (4.9)
0.47 156.8 (9.8)
0.47 235.2 (14.6)

Cementkg (lb)478.7 (29.8)
478.7 (29.8)
478.7 (29.8)
478.7 (29.8)

Coarse Agg
kg (lb)933.5 (58.1)
933.5 (58.1)
933.5 (58.1)
933.5 (58.1)

Fine Agg
kg (lb)783.8 (48.8)
705.5 (43.9)
627.1 (39.0)
548.7 (34.2)

Water
kg (lb)215 (13.4)
215 (13.4)
215 (13.4)
215 (13.4)

3.2 Casting and testing the specimen
Concrete was dry-mixed using pan mixer for about 5 minutes, thenadded water and continued mixing for another 5 minutes, after that it was

Use of Superfine Crumb Rubber to Improve Thermal & Sound Properties of Concrete269

July 2008, Thailand

poured into molds. Three tests were carried out: 1) Density, Voids andAbsorption (ASTM C642-97)(00), 2) Steady-State Heat Flux Measurement
and Thermal Transmission Properties (ASTM C177)(0) (Figure 5), and 3)
Acoustics Determination of Sound Absorption Coefficient and Impedancein Impedance Tube (ISO 10534-1:1996)(0)(Figure 6). Number of samples foreach test is summarized in Table 3.
Table 3: Casting schedule
Type ofconcretePC
10SCRC
20SCRC
30SCRC
Total

Number of specimen
Density
ThermalSound
Conductivit Absorpti
Void &
y
on
Absp
3
8
3
3
3
8
3
3
8
3
3
8
12

32

12

Figure 5: Steady-state heat flux measurement (ASTM C177)

Figure 6: Acoustics determination of sound absorption coefficient and
impedance in impedance tube (ISO 10534-1:1996)

270

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

4. EXPERIMENTAL RESULTS
4.1 Density, absorption and voids
As shown in Table 4 and Figure 7 the bulk density of concrete mixed
with crumb rubber was found to decrease gradually with the rubber content
comparing normal concrete. While the bulk density of normal concrete wasabout 2330 kg/m3 (145 lb/ft3), the average bulk density of 10%, 20% and
30% crumb rubber concrete were 2090, 1970 and 1820 kg/m3 (130, 122 and113 lb/ft3) , respectively.
The decrease in bulk density of concrete was partly due to thereplacement of a material with heavier specific gravity (fine aggregate) by alighter one (crumb rubber). The fine aggregate (River sand) used in thisstudy has an average specific gravity (oven dry) of 2.42, while the crumbrubber has an average of about 0.61. By calculation, at 10%, 20% and 30%
replacement ratio, the overall density of concrete was expected to decrease(due to the effect of crumb rubber alone) by 7.5%, 14% and 19.5%,
respectively. The actual results are slightly higher than the calculation andthis, perhaps, due to the effect of moisture in fine aggregate that did nottaken into account in the calculation.
In the case of the absorption and permeable void (Table 4, Figure 8,
unlike other lightweight aggregated concrete, the effect of crumb rubber
adding into concrete appeared to lower both absorption and permeable void
content. For conventional lightweight concrete, these two values would bequite high because of the high porosity in aggregates or large amount of air
bubble in cement paste. But when using super fine crumb rubber, eventhough the overall density of concrete decreased gradually with the rubber
content, the permeable void was found to decrease instead of increase.
Table 4: Bulk density, void and absorption
Type
PC
10%CR
20%CR
30%CR

Bulk Density
kg/m3(lb/ft3)
2330.0(145.1)2090.0(130.1)1970.0(122.7)1820.0(113.3)

Void
(%)
9.35
6.79
5.90
5.81

Use of Superfine Crumb Rubber to Improve Thermal & Sound Properties of Concrete

Absorption
(%)
4.26
3.51
3.39
2.98

271

July 2008, Thailand

Bulk Density (kg/cu.m)

2,500

2,000

1,500

1,000

500

0%

10%

20%

30%

% Replacement

Figure 7: Bulk density of PC vs. crumb rubber concrete
10

5.0
4.5
% Absorption

8

4.0

7

3.5

6

3.0

5

2.5

4

2.0

% Permeable
Voids

3

1.5

2

1.0

1

0.5

0

0.0
0%

10%

20%

% Absorption% Permeable Voids

930%

Concrete Type
Void (%)

Absorption (%)

Figure 8: Permeable voids and absorption
The decrease in permeable void and absorption was due to 1) the
porosity of crumb rubber particle and 2) the filling effect. In the case ofporosity, refer to Table 1, it could be seen that the specific gravity ofsuperfine crumb rubber under both SSD and oven dry conditions were quite
similar (0.61 and 0.62, respectively). These unchanged values indicated thatcrumb rubber was not a porous material. Therefore, by adding them into
concrete, no additional pore was added into the concrete pore system.
As for the filling effect, the small particle of superfine crumb rubber(SCRC) played a significant role in this part. With small particle size as
500-600 micron (0.0197 to 0.0234 in), the crumb rubbers were able to fill

272

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

up some of the capillary pores which led to the decrease in absorption from
4.26% to 2.98% as show in Figure 8.
4.2 Thermal conductivity
By definition, the quantity of heat transmitted through a unit thickness
in a direction normal to a surface of unit area, due to a unit temperature
gradient under steady state conditions is defined as the thermal conductivity
value (k). There are several parameters affecting the value of k in materials,
such as density, moisture content, temperature etc. In this case, let consider
only the density. Theoretically, the value of thermal conductivity is directly
proportional to the density; this means materials with low density willusually exhibit low value of k.
Based on the test results as shown in Figure 9 the k value of plain
concrete was found at 0.531 W/m.K (0.016 W/ft.K), while those of SCRC
were at 0.290, 0.275, and 0.267 W/m.K (0.0088, 0.0084, and 0.0081
W/ft.K) for 10SCRC, 20SCRC and 30SCRC, respectively. Comparing inpercentage, they are lower by about 44% to 49%. The lower values of k
indicated that SCRC is essentially a better insulator than plain concrete andis partly due to the lower density of SCRC than that of plain concrete.
According to Thailand Industrial Standard (TIS), the allowable valuesof k are specified within the range of 0.303 to 0.476 W/m.K (0.0092 to
0.0145 W/ft.K) for conventional lightweight concrete. The k-values of
SCRC obtained from this study were found to be less than or within theallowable range of those specified by TIS.

Thermal Conductivity (W/m.K)

0.016
0.500

Upper Bound

0.400

0.014
0.012

Allowable Range specified by TIS

0.010
0.300

Lower Bound

0.008
0.006

0.200

0.004
0.100
0.002
0.000

Thermal Conductivity (W/ft.K)

0.018

0.600

0.000
PC

10SCRC

20SCRC

30SCRC

Concrete Type

Figure 9: Thermal conductivity (k)Use of Superfine Crumb Rubber to Improve Thermal & Sound Properties of Concrete273

July 2008, Thailand

4.3 Heat transfer rate and heat resistivity
The rate of heat transfer per unit time (hour) and heat resistivity can becalculated using the following equations:
kAdT
(1)
q=
t

r=

t
k

(2)

where q = heat transferred per unit time (W/ hour ), r = heat resistivity(m2/kW, ft2/kW), A = heat transfer area (m2, ft2), k = thermal conductivity(W/m.K or W/m.oC, Btu/(hr oF ft2/ft)), dT = Temperature difference acrossthe material (K or oC, oF), t = material thickness (m, ft)
Using the value of k from the test and assuming that the temperature
difference between night and day is 12o C (= 285.15o K), the area is 1 x 1 m2
(0.093 ft2) and the thickness is 0.10 m (0.031 ft), the heat transfer andresistivity of both plain and CR concrete can be calculated as shown in
Table 5.

Table 5: Rate of heat transfer and heat resistivity
Type
PC
10SCRC
20SCRC
30SCRC

Heat Transfer
W/h
1,514
827
784
761

Heat Resistivity
m2/kW (ft2/kW)
0.19(0.018)0.34(0.032)0.36(0.033)0.37(0.034)

According to Table 5, all SCRC exhibited lower heat transfer rate andbetter heat resistivity than plain concrete. Both values were related to therubber content. The rate of heat transfer was found to decrease with theincreasing rubber content, while the heat resistivity went the opposite
direction.
4.4 Sound absorption
The ability of material to absorb sound at any particular frequency isdefined in form of the sound absorption coefficient (α). In general, for ahealthy young person, the hearing range is 15 to 18,000 hertz0). According
to the standard test, six different ranges of sound frequencies were used tomeasure the sound absorption of both plain and SCRC: 125, 250, 500, 1000,
2000 and 4000 Hz.
The variation of α for each material over the wide range of frequencies
can be high or low depending on material type. On the low side, forexample, a marble tile exhibits quite consistency values of 0.01, 0.01, 0.01,
0.01, 0.02, and 0.02 over the six frequency ranges. On the high side such as

274

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

a plaster board (for ceiling), it has rise and fall values from 0.15, 0.11, 0.04,
0.04, 0.07, and 0.08(0).
Results of both plain and SCR concrete are shown in Figure 10. It
could be seen that at the low frequency ranges of 125 and 250 Hz, bothplain and SCR concrete exhibited similar values of α. However, atfrequencies higher than 500 Hz, those of SCRC started to separate andbecame higher than that of plain concrete (Figure 10). High α indicated that
SCRC can absorb sound better at high frequency ranges than plain concrete.
In addition, the sound absorption of material can be illustrated using
another value so called the noise reduction coefficient (NRC). The NCR is
an average value of α at four frequencies in the middle range, can becalculated using the following equation.

NCR = (α 250 + α 500 + α 1000 + α 2000 ) 4(3)

Results of NCR against the density are given in Figure 11. Clearly, thenoise reduction depended mainly on the density of material. As the density
decreased, the noise reduction increased. For SCRC which density less thanplain concrete by about 20%, the noise reduction increased by about 46%.

0.40

α

0.30
0.20
0.10
0

1000

2000

3000

4000

Sound Frequency (Hz)PC

10SCRC

20SCRC

30SCRC

Figure 10: Sound absorption coefficient

Use of Superfine Crumb Rubber to Improve Thermal & Sound Properties of Concrete

275

0.25

2500.00.20

2000.0Density

0.15

1500.00.10

Noise Reduction

1000.0

0.05

500.0

-

0.0
PC

Density (kg/cu.m)

Noise Reduction

July 2008, Thailand

10SCRC 20SCRC 30SCRC
Concrete Type

Noise Reduction

Density

Figure 11: Noise reduction coefficient

5. CONCLUSIONS
1. Superfine particle crumb rubber has proved to improve the porosityand absorption of concrete by reducing both values up to about 38% and30%, respectively (at 30% replacement rate). With small particle size, thecrumb rubber is able to fill up some capillary pores and voids in concrete.
2. With smaller specific gravity than conventional fine aggregate, thecrumb rubber can reduce the density of concrete up to about 20% at the 30%
replacement rate.
3. SCRC also provides better insulating properties in both thermal andsound as seen by the decreasing thermal conductivity value and increasing
sound absorption coefficient as compare to those of plain concrete.

ACKNOWLEDGEMENT
The authors would like to thank the Thailand Research Fund-Master
Research Grants (TRF-MAG) for financially support this study and also
Union Pattanakit Co., Ltd., for providing crumb rubber.

REFERENCES
Rubber Research Institute, Statistic on the Use of Vehicle Tires in Thailand,
Ministry of Agriculture, Thailand (in Thai).
Mindess, S., Young, JF., and Darwin, D., 2003. Concrete 2nd Edition,
Prentice Hall.

276

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Neville, A.M., 1996. Properties of Concrete 4th Edition, Longman.
Young, JF., Mindess, S., Gray, RJ., Bentur, A., 1998. The Science andTechnology of Civil Engineering Materials. Prentice Hall.
Montreal Protocol, 1997. United Nations Environment Program, United
Nation.
Blackwell, M. C., and Pierce, C. E., 2002. Potential of Scrap Tire Rubber asLightweight Aggregate in Flowable Fill. Journal of Waste
Management, October, 23(9), 197-208.
Chesner, W. H., Collins, R.J., and MacKay, M.H., 1998. Users Guidelines
for Waste and By-Product Materials in Pavement Construction.
Report No. FHWA-RD-97-148, Commack: Chesner Engineering, P.C.,
April.
Eldin, N., and Senouci, A., 1994. Measurement and Prediction of theStrength of Rubberized Concrete. Cement and Concrete Composite,
No. 19, 287-298.
Eldin, N., and Senouci, A., 1993. Rubber-Tire Particles as Concrete
Aggregate. ASCE: Journal of Materials in Civil Engineering, Vol.5,
No.4, 478-496.
Fattuhi, N., and Clark, L., 1996. Cement Based Materials Containing
Shredded Scrap Truck Tyre Rubber. Construction and Building
Materials, Vol. 10, No. 4, 229-236.
Goulias, D.G., and Ali, A.H., 1998. Evaluation of Rubber-Filled Concrete
and Correlation between Destructive and Nondestructive Testing
Results. Journal of Cement, Concrete and Aggregates, 20(1), 140-444.
Huynh, H., Raghavan, D., and Ferraris, C., 1996. Rubber Particles from
Recycled Tires in Cementitious Composite Materials. NISTIR 5850 R;
May.
Khatib, Z.K., and Bayomy, F.M., 1999. Rubber Portland Cement Concrete.
Journal of Materials in Civil Engineering, 11(3), 206-213.
Maupin G.W., and Payne, C.W., 1997. Final Report Evaluation of AsphaltRubber Stress Absorbing Membranes, VTRC98-R11, Virginia
Transportation Research Council, September.
Morris, G. R., and McDonald, C.H., 1976. Asphalt -Rubber Stress
Absorbing Membranesfield Performance. Transportation Research
Record, 595, 99-108.
Rostami, H., Lepore, J., Silverstraim, T., and Zandi, I., 2000. Use of
Recycled Rubber Tires in Concrete, Proc. Int. Conf. Concrete ,University of Dundee, UK, 391-399.
Scofield, L. A., 1989. The History, Development, and Performance ofAsphalt Rubber at ADOT, Report Number AZ-SP-8902, ADOT,
December.
Topcu, I., 1995. The Properties of Rubberized Concrete. Cement andConcrete Research, No. 25, 304-310.
Zube, E., 1951. Experimental Field Use of Powdered Rubber in Bituminous
Plant Mix Surfacing. ID. 51-08, Division of Highway, State ofCalifornia.
ASTM DESIGNATION: C 136-96a, Test Method for Sieve Analysis of Fine
and Coarse Aggregates.
ASTM DESIGNATION: C 642-97, Test Method for Density, Absorption,
and Voids in Hardened Concrete.

Use of Superfine Crumb Rubber to Improve Thermal & Sound Properties of Concrete277

July 2008, Thailand

ASTM DESIGNATION: C 177-97, Test Method for Steady-State Heat Flux
Measurements and Thermal Transmission Properties by Means of theGuarded-Hot-Plate Apparatus.
ISO DESIGNATION: 10534-1, Test Method for Acoustics-Determination ofSound Absorption Coefficient and Impedance in Impedance Tubes.
Part 1: Method Using Standing Wave Ratio.
Lerder, Francis C., 2004. The Human Ear, Encarta Encyclopedia Deluxe.
CD-ROM.
http://www.saecollege.de/reference_material/pages/Coefficient%20Chart.ht
m

278

Joint Student Seminar on Civil Infrastructures

Student ReportREPORT FROM STUDENT PARTICIPANTS
ON THE JOINT STUDENT SEMINARON CIVIL INFRASTRUCTURES
Venue: Asian Institute of Technology, Bangkok, Thailand
Date: July 3 – 4, 2008

Student Participants (from left to right)
Naoki Sorimachi
Tomoya Kawasaki
Hiroaki Ebizuka
Michael Henry
Hiroaki Nishiuchi
Yusuke Matsumura

279

July 2008, Thailand

Presentation Session
On July 3rd, the presentation session washeld at the AIT Conference Center. First,
five professors from the participating
countries (Japan, Korea, and Thailand)gave lectures on their research topics.
After the professors’ lectures, 17 civilengineering students delivered their
Seminar Venue
presentations. The contents of the student presentations included a variety of
topics such as soil engineering, traffic management, disaster mitigation,
concrete engineering, and so on. Since there was such a wide range of topics,
I could learn about some fields which I normally don’t experience. The six
Japanese participants also delivered their presentations. The presentation
titles were:o Tomoya Kawasaki: Intermodal mode choice between Japan andRussiao Yusuke Matsumura: Evaluation of wildfire duration time over Asia
using MTSAT and MODISo Michael Henry: Utilizing heterogeneous engineering in concretematerial innovations for sustainable development
o Hiroaki Ebizuka: Laboratory stiffness measurements on Toyoura
sando Naoki Sorimachi: Seismic retrofitting promotion model for masonryhouses using PP-band method and micro-earthquake insuranceo Hiroaki Nishiuchi: OD variation analysis on the Tokyo
Metropolitan Expressway using ETC-OD data
All the presenters gave their best
effort during their presentation. I
thought the Japanese members are
conducting
meaningful
andinteresting research works, and theforeign students seemed to be quite
interested. The question and answer
sessions were also very productive
and we had useful discussion on the
Lively Discussion
research results. Through this session,
we could get a lot of information about the hot topics in civil engineering in
Asian countries. Furthermore, it was a good opportunity to practicepresentation and English skills.
(by Yusuke Matsumura)

280

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

Technical Visit:“Airport Rail Link Construction Site”
On July 4th, we visited the Suvarnabhumi airport rail link and city air
terminal project. This project aims to connect the airport to the central partof Bangkok by constructing 28 kilometers of elevated light rail and theaccompanying train stations. Currently, the only public transportation fromthe airport to Bangkok is by bus, so the airport users often suffer from thetraffic jams which occur in the city. This project aims to increase
accessibility to the airport as well as ease travelers’ troubles.
This project utilizes pre-cast segmental box-girder short-line casting method
to construct the elevated bridge. This method connects the pre-cast segments
at the construction site and integrates them by pre-stressing. Applying thismethod reduces the period of work at the site and improves quality.
The construction of the city air terminal
required a special method to erect theroof trusses. The trusses were assembled
next to the city air terminal and thenlifted onto the building and slide into
place.
The
const
ruction site itself was huge, withequipment and construction materials
piled everywhere. There were evensome dogs wandering around inside theconstruction site, and the ground wascovered with puddles from a recent
City Air Terminal Project Sitesquall. The picture on the right shows
the station under construction, including the impressive roof shape. The
station roof was composed of several sliding units, each containing one
steeple roof, and these units were slide into place before being connected tothe adjacent unit, as discussed above.
Airport Transit Extension

The inside the station was also huge.
The picture on the right shows theinside of the station. The scope of the
project could be felt in the main
terminal area, where construction
workers were assembling panels for theceiling about 30 meters above the floor.
Inside the Main Building
We could walk around the construction
area quite freely and approach near the workers. This sort of accessibility is
impossible in Japan due to security and safety issues.
(by Hiroaki Ebizuka & Naoki Sorimachi)

Report from student participants on the Joint Student Seminar on Civil Infrastructures

281

July 2008, Thailand

Impressions from the Student Participants
I attended the Joint Student Seminar on Civil
Infrastructures held at the Asian Institute ofTechnology (AIT) in Thailand on the 3rd
and 4th of July, 2008. AIT, my alma mater, islocated in the Thailand Science Park (TSP),
50 kilometers north of Bangkok. Thislocation is similar to Tsukuba city in Japan.
The topic of my presentation wasinternational intermodal logistics. After my presentation, a Vietnamesestudent from a Korean university asked about my presentation. This time
was very fruitful to deepen my awareness towards study and stimulate mythinking. In addition, I was fortunate to have the opportunity to discuss witha Korean professor the current logistics condition and issues in Korea.
Thanks to several discussions at this seminar, I again realize the importanceof communication with researchers. Lastly, I would like to express myprofound gratitude and appreciation to the professors and students from the
University of Tokyo (UOT) and AIT. I got a lot of stimulation from thisseminar and would like to use this experience towards my future activities.
(by Tomoya Kawasaki)
The Joint Student Seminar on Civil Infrastructures provided me with a good
opportunity to visit Thailand (for the first time), as well as share myresearch works and practice making presentations. The other students’presentations were from a wide variety of fields, which gave me the chance
to learn about different areas in civil engineering. The site visit was
extremely interesting; Thai construction companies run their construction
sites in such a different manner from Japan or the
USA that I was quite surprised. We were able towander around the inside of the main train terminal,
even as construction works were going on around us.
Also, the construction site itself was very cluttered,with garbage and materials. However, on the whole,it was definitely a valuable chance to not only learn
about other countries’ research works, but also to
see how construction is managed in a different
country. (by Michael Henry)
The AIT seminar was the first international
conference in my life that I participated in as apresenter. I learned that the most important thing
when presenting is to make listeners understandwhat you want to say. Use easy words and phrases,
and be simple. I think this is true in international
communication, too. I strongly felt this when I waschatting with a guy from Korea during lunch. I’mlooking forward to joining AIT seminar again.
(by Naoki Sorimachi)

282

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

This is my first international seminar and first visit toThailand, and even my first presentation to people
who belong to other universities. I experienced manythings that I had not done before through thisseminar. They made me able to see things inperspective. Contact with Thai and Korean students
studying in the same field as me helped increase my
motivation to study. I want to make good use of
these experiences and keep studying. I wish to
express my gratitude to those people related to thisseminar. (by Hiroaki Ebizuka)
The Joint Student Seminar on Civil Infrastructures
gave me a good opportunity to discuss with otherfields’ researchers and students. There were not a lot
works related to my research area (Traffic
Engineering), but I received some comments whichreminded me to think about basic background,concept, methodology and so on. We also had atechnical visit to see the “Airport rail link”
construction site. This is the new railway between
Bangkok International Airport and Bangkok. First
we listened to an introduction about the construction method and thenmoved to the actual construction site. I was impressed by the construction
method of the station roof, especially since it was designed with such amodern style! I really look forward to riding the new train system next time
I visit. I also had a good time with a researcher from Thailand who stayed in
our laboratory. These days were an amazing time in Thailand!
(by Hiroaki Nishiuchi)
It was a great pleasure for me to join the Joint
Student Seminar for Civil Infrastructures. This was
my first time to give a presentation in front offoreign students and researchers. I learned a lot
through the experience, not only by giving mypresentation at AIT but also the preparation for it inJapan. It really cheered me up to develop English
skills. Moreover, events other than presentation
session during the seminar like the engineering tour
were also very meaningful and enjoyable. I hope tojoin this kind of seminar again in the future if I have the chance. For the
student seminar next year, I think it is better to better encourage intercultural communication among the participants. I appreciate the effort andwork of everyone who organized and supported this great event.
(by Yusuke Matsumura)

Report from student participants on the Joint Student Seminar on Civil Infrastructures283

July 2008, Thailand

I had a great time when I attended the Joint
Student Seminar on Civil Infrastructures
held at the Asian Institute of Technology(AIT) in Thailand. I had my presentation in
English in front of many foreigners for the
first time and also I was able to listen tovarious presentations of other foreign
students. Actually, I am studying about thestructure analysis in master’s course, so I don’t know well other parts ofcivil engineering. Nevertheless it was very interesting and really goodexperience to me because I seldom had a chance to listen to other fields ofcivil engineering. Lastly, I want to thank all of people attended this seminarfor giving me a chance to have wonderful memories in Thailand. I hope thisJoint Student Seminar will be activated and held continuously.
(by Choi, Sung Woo)

The first joint student seminar was so
impressive. I would like to express mysincerethankstoallparticipants, particularly to the organizing
team who brought this seminar to oneof my memorable events at AIT. The
thing I loved most is that every student
can have their own stage to present
and contribute their scholastic idea alongwith listening to others. I really wish not only the continuance of this
precious activity, but also the long-lasting relationship among theparticipants.
(by Adisorn Owatsiriwong)This is the first time for me to join theinternational conference as a presenter.
It can be said that a lot of presentation
experience has been gained through theconference. Moreover, this is a goodchance for me to know more about
education in other country and can
improve my English skill. I hope that I
could join the next year conference.
(by Tran Viet Dung)

284

Joint Student Seminar on Civil Infrastructures

ICUS Report 30

It is my great opportunity to present myresearch work at the Joint Student
Seminar on Civil Infrastructures held at
Asian Institute of Technology, Thailand.
I get appreciably not only the experiencein the presentation in the English
communication, also the technicalinformation from various fields in Civil
Engineering which I never focus on. This seminar, in addition, pushes me todevelop an idea and expand scope of the study in my doctoral dissertation. I
finally would like to use this chance to thank all attendees who give me thevaluable knowledge.
(by Ekkachai Yooprasertchai)

The Joint Student Seminar on Civil
Infrastructures held at the Asian
Institute of Technology (AIT) in
Thailand on the 3rd and 4th of July,
2008. This was my first time to give a
presentation in front of foreign students
and researchers. I learned that the mostimportant thing when presenting is tomake listeners understand. It really cheered me up to develop English skills.
The other students’ presentations were from a wide variety of fields, whichgave me the chance to learn about different areas in civil engineering. They
made me able to see things in perspective. I’m looking forward to joining
AIT seminar again and appreciate the effort and work of everyone whoorganized and supported this great event. Finally, thank you everyone to
make this conference.
(by Kittipong Suweero)

Report from student participants on the Joint Student Seminar on Civil Infrastructures285