地震動を受ける地盤に対する埋戻し材としての流動化処理土の適用
メタデータ

言語: English
出版者:
公開日: 2021-06-23
キーワード (Ja):
キーワード (En):作成者: フェム, クァン ヴォン
メールアドレス:所属:

URL

https://doi.org/10.15118/00010398

APPLICATION OF LIQUEFIED STABILIZED SOIL ASBACKFILLING MATERIAL TO GROUND SUBJECTEDTO SEISMIC MOTION

By
PHAM QUANG VUONGA DISSERTATION SUBMITTED TO THE FACULTY OF THE
MURORAN INSTITUTE OF TECHNOLOGYIN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF ENGINEERINGDIVISION OF CIVIL AND ENVIRONMENTAL ENGINEERINGMURORAN INSTITUTE OF TECHNOLOGY
March 2021

Acknowledgments
I would never have been able to finish my Ph.D. course without the guidance andunderstanding of my supervisors, assistance from lab-mates, friends, and support from myfamily.
First and foremost, I would like to express my sincere gratitude to my advisor
Professor Yukihiro Kohata for the continuous support of my Ph.D. study and related researchfor his patience, motivation, and immense knowledge. His guidance helped me in all the timeof research and writing of this thesis.
Similar gratitude belongs to the members of my thesis committee: Professor Shima
Kawamura and Associate Professor Noriyuki Sugata, for their insightful comments andencouragement, but also for the hard question which incented me to widen my research fromvarious perspectives.
My sincere thanks also go to all the students in my laboratory, who are responsible
for organizing seminars and many interesting activities in our laboratory. These activities
helped us have a funny and friendly life in the laboratory.
Besides, I am grateful to all the staff of the Centre for International Relations,Muroran IT: Mr. Jinro Endo, Ms. Hatsuki Noda, Mr. Sangyub Baek, Ms. Mai Ikeda, and Ms.
Kozue Takekawa for making my life in Hokkaido really comfortable and enjoyable. Especiallythanks to Associate Professor Naoko Yamaji and Associate Professor Masatsugu Ono, whotaught the Japanese language that helps me to integrate into life in Japan.
Furthermore, I also sincerely thank Associate Professor Le Anh Dung and Associate
Professor Nghiem Manh Hien of the Hanoi Architectural University for offering me
recommendation letters to apply for the doctor course. I also thank the Technology andConstruction Management Department, Civil Engineering Faculty, and Hanoi Architectural
University for creating good conditions to study at Muroran IT. Thanks are also extended to
Dr. Duong Quang Hung and Dr. Nguyen Cong Giang for their introduction andrecommendation to Muroran Institute of Technology and Professor Kohata before applying
for a doctor course here.
Words are not enough to thank my family members for the support they have givenme during this long and sometimes difficult journey. I would very much like to express mylove and gratitude to my parents, my wife (Dinh Mai Huong), my son (Pham Quang Minh),and my daughter (Pham Huong Giang) for their love and support and for instilling in me thevalue of learning and providing me outstanding opportunities to do so throughout my life.
Without their endless help, I would not be able to achieve and enjoy these successes.
Muroran, March 01, 2021
Pham Quang VuongiAbstract
Excavated soil from the construction site is a serious problem in the big city in developing
countries. Liquefied Stabilized Soil (LSS), which is an effective method of reusing excavated soil withconstruction works has become popular in Japan. The LSS is a kind of cement-treated soil of slurry
type prepared by mixing soil, water, and cement solidification. The LSS is not only created stabilized
ground without compaction but also easy to be able to fill empty space by pumping a long distance. In
this study, the deformation characteristic and new advantage of LSS were investigated to promote theapplication of LSS in construction practice. Research works, including experiments and analyses, havebeen conducted. This study is summarized as follows:(1) The effects of various factors, which are curing days, paper content, curing temperatureand curing circumstance, etc., on strength and deformation property of LSS prepared at field were
investigated. Two pits were excavated on the campus and then were filled with LSS mixed with fiber
material amount 0 and 10 kg/m3, respectively. After a curing time of 28 and 56 days, the specimens
were prepared by trimming LSS retrieved from the model ground. A series of Consolidated-Undrained
triaxial compression tests with pore water measurement (CUB test) was carried out on the specimens
cured in the field ground under the conditions at an axial strain rate of 0.054 %/min and the effective
confining pressure of 98 kPa. And also, the applicability of an evaluation of stiffness by the Portable
FWD test (Falling Weight Deflectometer test) at a backfilling ground by LSS mixed with fiber material
was investigated. Based on the test results, it was found that the curing temperature could affect the
maximum deviator stress qmax of LSS. As for LSS with fiber material, there is independent of the qmax
on the curing temperature when curing days increase. And the effect of curing temperature on Initial
Young’s modulus E0 is smaller than that of curing days. It was considered that during the first periodof the curing process of LSS mixed fiber material, the addition of the fiber material into LSS is reduced
the damage degree during shear. It was found that the K-value by portable FWD can be adequately
evaluated the stiffness of backfilling ground by LSS with fibered material.
(2) The effect of backfilling material on the building and ground subjected to seismic motion
is analyzed by using the finite element method (FEM). A three-dimensional model of the building andground was simulated in ABAQUS software. A reinforced concrete ten-floor building frame, 30 m highand 12 m wide with 16 columns consisting of three spans of 4 m in each direction, and one basement
was selected in this simulation. The 1968 Tokachi-Oki earthquake in Hachinohe (Japan) was selected
and utilized on the finite element numerical model to conduct a time-history analysis. Three casestudies with three types of backfilling material: backfilling soil (sandy soil), LSS, and LSS with fiber(10 kg/m3) were analyzed. Based on the analysis results, it was found that using LSS and LSS withfiber as a backfilling material reduce the lateral displacement and inter-story drift of building under theseismic condition. On the other hand, the application of LSS and LSS with fiber as a backfill material
significantly decreases the acceleration and velocity of the ground around the building and adjacentareas. Therefore, it is considered that the LSS and LSS with fiber have an effective potential to reduce
the seismic motion on the buildings and the surrounding ground. This property is a new advantage of
LSS and LSS with fiber. And more, the effect of fiber material mixed with LSS was made clear in thisstudy. LSS mixed with fiber has more advantageous than LSS.

ii

Table of Contents

Acknowledgments ................................................................................................................................................................... i
Abstract ........................................................................................................................................................................................... ii
List of Tables...........................................................................................................................................................................................vi
List of Figures ............................................................................................................................................................................. vii
CHAPTER 1
INTRODUCTION ......................................................................................................................................................................... …1
1.1 BACKGROUND OF RESEARCH ..................................................................................................................... 1
1.2 OBJECTIVE OF RESEARCH ............................................................................................................................... 4
1.3 THESIS OUTLINE ......................................................................................................................................................... 7
REFERENCES ........................................................................................................................................................................... 9
CHAPTER 2OVERVIEW OF LIQUEFIED STABILIZED SOIL ...................................................................................... …10
2.1 INTRODUCTION .......................................................................................................................................................... 10
2.2 COMPONENT OF LIQUEFIED STABILIZED SOIL ........................................................................ 11
2.2.1 Soil ........................................................................................................................................................................... 122.2.2 Cementitious materials .............................................................................................................................. 122.2.2.1 Blast furnace slag ........................................................................................................................ 122.2.2.2 Lime...................................................................................................................................................... 13
2.2.2.3 Cement ................................................................................................................................................ 14
2.2.2.3 Fly ash ................................................................................................................................................. 14
2.2.2.4 Pozzolana .......................................................................................................................................... 16
2.2.3 Fiber materials ................................................................................................................................................. 16
2.2.3.1 Newspaper fiber ........................................................................................................................... 16
2.2.3.2 Coir fiber ........................................................................................................................................... 17
2.2.3.3 Papyrus fiber ................................................................................................................................... 18
2.2.3.4 Polypropylene fiber.................................................................................................................... 19
2.2.3.5 Flax fiber and bamboo strip ................................................................................................. 19
2.3 HISTORICAL DEVELOPMENT OF LIQUEFIED STABILIZED SOIL.............................. 21
2.4 APPLICATIONS OF LIQUEFIED STABILIZED SOIL IN CONSTRUCTION .............. 26
REFERENCES........................................................................................................................................................................... 32iii

CHAPTER 3
MATERIALS AND PREPARATION METHOD OF SPECIMEN .................................................... …36
3.1 INTRODUCTION .......................................................................................................................................................... 36
3.2 TEST MATERIALS....................................................................................................................................................... 36
3.2.1 Snow Fine Clay............................................................................................................................................... 36
3.2.2 Cement .................................................................................................................................................................. 37
3.2.3 Pulverized newspaper ................................................................................................................................. 38
3.2.3 Water....................................................................................................................................................................... 39
3.3 MIXING METHOD ...................................................................................................................................................... 39
3.4 SPECIMEN PREPARATION ................................................................................................................................. 43
3.4.1 Preparation method of the specimen at laboratory .............................................................. 43
3.4.2 Preparation method of the specimen at field .............................................................................. 44
REFERENCES........................................................................................................................................................................... 47
CHAPTER 4
APPARATUS AND TESTING PROCEDURES .................................................................................................. …48
4.1 INTRODUCTION .......................................................................................................................................................... 48
4.2 APPARATUS AND TESTING PROCEDURES ....................................................................................... 48
4.2.1 Experiment at laboratory .......................................................................................................................... 48
4.2.1.1 Triaxial apparatus ........................................................................................................................ 48
4.2.1.2 Test procedure................................................................................................................................ 53
4.2.2 Experiment at field ....................................................................................................................................... 53
4.2.2.1 Falling weight deflectometer (FWD) ............................................................................ 53
4.2.2.2 Test procedure................................................................................................................................ 57
REFERENCES........................................................................................................................................................................... 58
CHAPTER 5
VARIOUS FACTORS ON THE STRENGTH AND DEFORMATION PROPERTY OF
LIQUEFIED STABILIZED SOIL PREPARED AT FIELD ..................................................................... …59
5.1 INTRODUCTION .......................................................................................................................................................... 59
5.2 TEST PROCEDURE..................................................................................................................................................... 60
5.2.1 Test materials .................................................................................................................................................... 60
5.2.2 Mixing method ................................................................................................................................................ 61
5.2.3 Specimen preparation ................................................................................................................................. 61
5.2.4 Test method and equipment .................................................................................................................... 63iv

5.2.4.1 CUB test ............................................................................................................................................ 63
5.2.4.2 Portable FWD test....................................................................................................................... 64
5.3 TEST RESULTS AND DISCUSSION ............................................................................................................. 66
5.3.1 Relationship between deviator stress and axial strain .......................................................... 66
5.3.2 Deformation property ................................................................................................................................. 68
5.3.2.1 Definition of Young’s modulus.......................................................................................... 68
5.3.2.2 Initial Young’s modulus E0 ................................................................................................... 69
5.3.2.3 Tangent Young’s modulus Etan ........................................................................................... 69
5.3.2.4 Equivalent Young’s modulus Eeq ...................................................................................... 70
5.3.3 Strain level-dependency of Young’s modulus ........................................................................... 71
5.4 SUMMARY......................................................................................................................................................................... 72
REFERENCES........................................................................................................................................................................... 73
CHAPTER 6
EVALUATION OF THE REDUCTION OF THE SEISMIC MOTION TO GROUNDSUBJECTED BY USING LIQUEFIED STABILIZED SOIL ................................................................ …75
6.1 INTRODUCTION .......................................................................................................................................................... 75
6.2 NUMERICAL SIMULATION ............................................................................................................................... 76
6.2.1 Simulation of study cases......................................................................................................................... 76
6.2.2 Numerical modeling and parameter.................................................................................................. 76
6.2.2.1 Structural modeling.................................................................................................................... 76
6.2.2.2 Soil modeling and characteristic of backfilling materials ............................... 79
6.2.2.3 Seismic motion.............................................................................................................................. 82
6.2.2.4 Numerical modeling in the ABAQUS program ..................................................... 83
6.3 RESULTS AND DISCUSSION ............................................................................................................................ 86
6.3.1 Maximum lateral displacement and inter-story drift ............................................................. 86
6.3.2 Relationship between acceleration and velocity with distance ...................................... 87
6.4 SUMMARY......................................................................................................................................................................... 90
REFERENCES........................................................................................................................................................................... 92
CHAPTER 7
CONCLUSIONS AND SUGGESTIONS ................................................................................................................... …94
7.1 CONCLUSIONS.............................................................................................................................................................. 94
7.2 RECOMMENDATIONS ............................................................................................................................................ 95v

List of Tables

Table 3.1 Physical parameters of NSF-Clay ................................................................................................... 37
Table 5.1 Physical properties of NSF-Clay ..................................................................................................... 61
Table 6.1 Characteristic of designed reinforced concrete column sections adopt in 3D
FEM ............................................................................................................................................................................................. 77
Table 6.2 Characteristic of designed reinforced concrete floor slabs and foundations
adopted in a 3D numerical model........................................................................................................................... 78
Table 6.3 Parameters of backfilling materials ................................................................................................ 81
Table 6.4 Rayleigh damping coefficients of the soil ................................................................................ 82
Table 6.5 Characteristics of the adopted earthquake records ............................................................. 82vi

List of Figures

Figure 1.1 Density of high-rise buildings has significantly increased in recent years in
Jakarta city............................................................................................................................................................................... 2
Figure 1.2. Serious traffic congestion in Jakarta city ................................................................................ 2
Figure 1.3 Air pollution in Jakarta city ............................................................................................................... 3
Figure 1.4 Orientation for BRT, metro and urban railway network in Jakarta city ............. 3
Figure 1.5 Flow chart of this dissertation ......................................................................................................... 7
Figure 2.1 The components of Liquefied Stabilized Soil ...................................................................... 11
Figure 2.2 Fiber material was made by the newspaper ........................................................................... 17
Figure 2.3 Coir fiber......................................................................................................................................................... 18
Figure 2.4 Papyrus before drying and crushing (a) and after treatment and sieving (b). 18
Figure 2.5 Polypropylene fiber ................................................................................................................................. 19
Figure 2.6 Flax fiber (a) and bamboo strip (b) ...............................................................................................20
Figure 2.7 Use of LSS for filling the cavity under the road surface .............................................. 26
Figure 2.8 LSS used for backfill at the upper part of the cut and cover tunnel ..................... 27
Figure 2.9 LSS used for invert material of shield tunnel ....................................................................... 27
Figure 2.10 Flow of Liquefied soil stabilized method .............................................................................. 28
Figure 2.11 Using LSS for various backfilling works in Japan......................................................... 28
Figure 2.12 Backfilling of LSS ................................................................................................................................. 29
Figure 2.13 Production system for foam mixed lightweight soil ...................................................... 30
Figure 2.14 Cement treated soil using as slope protection .................................................................... 30
Figure 2.15 Placement of cement-treated soil along slope .................................................................... 31
Figure 3.1 New Snow Fine Clay ...........................................................................................................................37
Figure 3.2 Geoset 200 cement.................................................................................................................................... 38
Figure 3.3 The pulverized newspaper..............................................................................................................39
Figure 3.4 Available range of slurry density .............................................................................................40
Figure 3.5 Bucket and electronic scale ................................................................................................................. 40
Figure 3.6 NSF-Clay and water were mixed in the bucket by hand mixer ............................ 41
Figure 3.7 The density of the mixture was checked by AE mortar container ........ 41
Figure 3.8 Sealed container for removing air bubbles........................................................................42
Figure 3.9 Plastic box ....................................................................................................................................................... 43
Figure 3.10 Curing specimen ...................................................................................................................................... 43vii

Figure 3.11 The mass of the sample was checked........................................................................................ 44
Figure 3.12 Schematic drawing of pits and specimen at the test field............................................ 44
Figure 3.13 Curing sample under the nature condition ............................................................................. 45
Figure 3.14 Temperature sensor installed in the excavation hole...................................................... 45
Figure 3.15 The samples prepared by trimming LSS retrieved from the test field................ 46
Figure 4.1 The drawing of the apparatus for triaxial compression tests ...................................... 50
Figure 4.2 Dial gauge ....................................................................................................................................................... 51
Figure 4.3 Gap sensor ...................................................................................................................................................... 51
Figure 4.4 Setting LDT on the test sample ....................................................................................................... 52
Figure 4.5 Pore pressure and cell pressure transducer .............................................................................. 52
Figure 4.6 The triaxial compression test procedure.................................................................................... 53
Figure 4.7 Falling Weight Deflectometer (FWD) apparatus ................................................................ 54
Figure 4.8 Portable Falling Weight Deflectometer (PFWD) apparatus ........................................ 54
Figure 4.9 The typical structure of PFWD ........................................................................................................ 56
Figure 4.10 An example of displacement and loading stress at one measurement
point .............................................................................................................................................................................................. 56
Figure 4.11 The PFWD test procedure ................................................................................................................. 57
Figure 5.1 Schematic drawing of pits .................................................................................................................. 62
Figure 5.2 Setting temperature sensor in the model ground ............................................................... 63
Figure 5.3 Schematic figure of the test apparatus ........................................................................................ 64
Figure 5.4 Schematic of portable FWD test apparatus ............................................................................. 65
Figure 5.5 Relationship between temperature and curing date .......................................................... 66
Figure 5.6 Relationship between qmax and temperature ........................................................................... 67
Figure 5.7 Relationship between deviator stress q and axial strain εa ........................................... 67
Figure 5.8 Definition of various Young's moduli ........................................................................................ 68
Figure 5.9 Relationship between E0 and temperature ............................................................................... 69
Figure 5.10 Etan/E0 ~ q/qmax relations .................................................................................................................... 70
Figure 5.11 Eeq/E0 ~ q/qmax relations ..................................................................................................................... 71
Figure 5.12 EP.FWD and Etan ~ log εa relations ................................................................................................. 71
Figure 6.1 Dimension of the structure and excavation .............................................................................. 77
Figure 6.2 The natural frequencies of the structure .................................................................................... 79
Figure 6.3 The relationship between deviator stress and axial strain of LSS and LSS
with fiber ................................................................................................................................................................................... 80
viii

Figure 6.4 The time histories of the 1968 Tokachi-Oki earthquake in Hachinohe cityin Japan ....................................................................................................................................................................................... 83
Figure 6.5 Element types used in FEM ............................................................................................................... 84
Figure 6.6 The FEM of the structure and ground in the ABAQUS software program ... 85
Figure 6.7 Maximum lateral displacement of the 10-story structure supported by pilefoundation under the 1968 Tokachi- Oki earthquake ................................................................................ 86
Figure 6.8 The inter-story drift of the 10-story structure supported by pile foundation
under the 1968 Tokachi – Oki earthquake ........................................................................................................ 87
Figure 6.9 Maximum horizontal acceleration at points A, B, C, D, and E ............................... 88
Figure 6.10 Maximum vertical acceleration at points A, B, C, D, and E.................................... 89
Figure 6.11 Maximum horizontal velocity at points A, B, C, D, and E ....................................... 89
Figure 6.12 Maximum vertical velocity at points A, B, C, D, and E ............................................. 90ix

CHAPTER 1
INTRODUCTION

1.1. BACKGROUND OF RESEARCH
Nowadays, in developing countries with rapid economic growth, the speed ofurbanization and modernization in big cities is happening strongly, this is also an
inevitable trend in big cities. It was accompanied by a series of urgent social problems
such as rapid population explosion, severe traffic congestion, environmental pollution,and the state of infrastructure, which does not meet society's needs, etc.
Typically Jakarta, the capital of Indonesia. According to the government's
documents "Jakarta in Figures", Jakarta city has a population growth rate of about 1.9 %per year with 10.77 million people in 2020, exceeding all the government's prediction
about the city's population. Jakarta has an area of 664 km2, with a population density of
16220 people/ km2, and become the world's ninth most densely populated metropolitan
region. The population is growing too fast, leading to the demand for housing, parking,and shopping mall, etc., increase significantly. To solve the above problem, and withlimited urban land area, the construction of high-rise buildings with many basements andunderground facilities like underground parking is the most effective solution. The
construction density of skyscrapers in Jakarta city is very high, as shown in Figure 1.1.
The quickly increasing population is also leading to an infrastructure that does
not meet human movement needs. Jakarta has ranked 10th on the list of the mostcongested cities in the world in 2019 based on the TomTom Traffic index uploaded on
the tomtom.com website. Indonesia's government recently reported that traffic congestionin Jakarta's inner city and vicinity had caused losses of up to 65 trillion rupiahs (equivalent
to nearly 4.7 billion USD) per year. The frequent traffic congestion during rush hours
every day, which happened on a large scale, as shown in Figure 1.2. Most of the trafficin Indonesia use private vehicles such as motorbikes and private cars, so a huge amountof emissions from vehicles contribute to environmental pollution. A report published in1early 2019 by the organization Greenpeace affirms that Jakarta is the most polluted city
in Southeast Asia (Figure 1.3). Throughout 2018, the ultrafine dust index (PM 2.5) inJakarta stood at 45.3 µg (micrograms)/ m3, four times higher than the maximum standard
set by the World Health Organization (WHO) and 3 times higher than the maximum
permitted level according to the national standards of Indonesia. Due to the city's urgent
problem, the government has come up with optimal solutions such as expanding thetransport infrastructure network, improving the transport capacity of public transport,
encouraging people to use public facilities, etc. Therefore, the construction plans for thetransport system were formed in 2013 to modernize the traffic. The World's longest bus
rapid transit (BRT) system with a length of 230 kilometers, the Metro Jakarta Electrified
Train System with 418 kilometers length consisting of 1 elevated line and 5 at groundlevel were built (Figure 1.4). The Indonesian government hopes these projects can solve
both the traffic and the environmental problem.

Figure 1.1 Density of high-rise buildings has significantly increased in recent years in
Jakarta city

Figure 1.2 Serious traffic congestion in Jakarta city2Figure 1.3 Air pollution in Jakarta city

Figure 1.4 Orientation for BRT, metro and urban railway network in Jakarta city
However, it is predicted that millions of cubic meters of excavated soil will arise
to be trucked from underground construction projects to disposal sites. It is the cause ofenvironmental pollution. Besides, sand from rivers and rocks from mountains is the mainmaterial used as backfilling soil in the constructions. It is leading to increasingly depleted
natural resources and serious impacts on the natural environment. On the other hand, thedisposal sites are becoming increasingly scarce and overloaded in the big cities.

3

Therefore, the excavated soil is a serious problem in the big cities in developing
countries as Jakarta. The questions are where to put the excavated soil and how to develop
sustainable infrastructure, which does not only reduce the cost of construction but also
does not affect the natural environment.
A long time ago, in the big cities in Japan, such as Tokyo, Kyoto, and Osaka,
when the subway lines, underground constructions, and high-rise buildings were built,
the Japanese government also faced this same situation in Jakarta. In Japan, the excavatedsoils generated from the urban construction site is often discarded as industrial waste at
the dump. According to the research report: the average lifespan of landfills in Japan isestimated to be 13.6 years, 14 years in the Kinki region, and only 4.3 years in the Tokyo
metropolitan area. Furthermore, it can be seen that the excavated soil has not been widelyand effectively used for a long period. Therefore, how to reuse the excavated soil has
become an urgent problem to be solved. To solve this problem, Japan launched aconstruction waste promotion plan in May 2000, and the construction recycling law wasestablished. Since then, the reuse of excavated soil has been studied and applied inpractice.
1.2. OBJECTIVE OF RESEARCH"Liquefied Stabilized Soil" (LSS), which was mentioned by Kuno (1997), is oneof the effective methods of using the excavated soil with construction works and has
become popular in Japan. The LSS is a kind of cement-treated soil, which is prepared bymixing slurried soil and cement stabilizer. The LSS mixtures are not only createdstabilized ground without compaction but also easy to fill empty space by pumping a long
distance. However, according to previous studies, it is shown that the increase in cement
content does not only increase the strength property but also the brittleness increases.
Therefore, Kohata et al. proposed the LSS mixed the pulverized newspaper as fiber
material to improve the brittle mechanical property and increase the ductile performanceof LSS (Kohata et al., 2002). It was shown that the ductile property of LSS mixed withpulverized newspaper as a fiber material after the peak in the q~εa curve was significantly
improved by the reinforcement method (Kohata, 2006; Kohata et al., 2004 and 2007; Itoet al., 2011). However, it has not been explained about the influences of various factors
on the strength and deformation property of LSS with fiber material prepared at field(Duong et al., 2014).

4

On the other hand, previous studies have shown that using LSS as a backfillingmaterial can reduce train-induced vibration (Duong, 2015) and reduce vehicle-induced
vibration (Do, 2019). It can be seen that LSS can reduce vibrations from different smallor large vibration sources. However, no studies have evaluated the effect of LSS on thesurrounding environment when an earthquake occurs. Especially Japan is one of thecountries with the highest number of earthquakes in the world every year. According toannual statistics, earthquakes cause a lot of damage to buildings and traffic. If theapplication of LSS as a backfilling material can reduce the impact of earthquakes on thesurrounding environment, it will be a new advantage of LSS. It will promote increased
use of LSS not only in Japan but also in other countries around the world like Indonesia,
Philippines, etc. For the reasons above, the main points of this research are as follows:o The influences of various factors, which are curing days, paper content, curing
temperature and curing circumstance, etc., on strength and deformation propertyof LSS prepared at field were investigated and discussed.
o Evaluated the effect of LSS as backfilling material on the ground and building
when an earthquake occurs by the finite element method (FEM).
To clear up the above points, the following works were carried out in this research:
Firstly, two pits were excavated on the campus and then were filled with LSS
mixed with fiber material amount 0 and 10 kg/ m3, respectively. After a curing time of 28
and 56 days, the specimens were prepared by trimming LSS retrieved from the model
ground. A series of Consolidated-Undrained triaxial compression tests with pore watermeasurement was carried out on the specimens cured in the field ground under theconditions at a constant strain rate of 0.054 %/ min and the effective confining pressureof 98 kPa. And also, the applicability of an evaluation of stiffness by the Portable Falling
Weight Deflectometer (PFWD) test at a backfilling ground by LSS mixed with fiber
material was investigated. Based on the test results, the influences of various factors,
which are curing days, paper content, curing temperature and curing circumstance, etc.,
on the strength and deformation property of LSS prepared at the field are discussed.
Secondly, the effect of backfilling material on the building and ground under theearthquake is analyzed by using the finite element method (FEM). A three-dimensionalmodel of the ground and construction was simulated in ABAQUS software. A reinforced
concrete ten-floor building frame, 30 m high and 12 m wide with 16 columns consistingof three spans of 4 m in each direction, and ten slabs and one basement was selected in5this simulation. The height of the floors was 3 m, and the basement floor was located at a
depth of 4.5 m below the ground surface. The reinforced concrete foundation was 15x15
m square and 1 m thick, and the reinforced concrete pile of 20 m depth and 1.2 m indiameter was selected to analyze in this study. The 1968 Tokachi-Oki earthquake in
Hachinohe (Japan) was selected and utilized on the finite element numerical model toconduct a time-history analysis. Three case studies with three types of backfillingmaterial: backfilling soil, LSS, and LSS with fiber were analyzed. Base on the analysis
results, the effect of backfilling material on the displacement and inter-story drift ofbuilding and acceleration and velocity of five points on the ground surface in each casewere compared and investigated.

6

1.3. THESIS OUTLINEAPPLICATION OF LIQUEFIED STABILIZED SOIL ASBACKFILLING MATERIAL TO GROUND SUBJECTED TO
SEISMIC MOTION

CHAPTER 1
INTRODUCTION

CHAPTER 2OVERVIEW OF LIQUEFIED STABILIZED SOIL

CHAPTER 3
MATERIAL AND PREPARATION METHOD OF
SPECIMENCHAPTER 4
APPARATUS AND TESTING PROCEDURES

CHAPTER 5
VARIOUS FACTORS ON THE STRENGTH AND
DEFORMATION PROPERTY OF LSS PREPARED AT
FIELD

CHAPTER 6
EVALUATION OF THE REDUCTION OF THE SEISMIC
MOTION TO GROUND SUBJECTED BY USING LSSCHAPTER 7
CONCLUTIONS

Figure 1.5 Flow chart of this dissertation

7

As seen in Figure 1.5, this dissertation contains seven chapters. The introduction(CHAPTER 1) describes the general background, purpose, and objectives of the researchand organization of the dissertation.
CHAPTER 2 introduces a brief overview of LSS as an effective method for theutilization of excavated soil and its applications.
CHAPTER 3 presents the materials and preparation method of the specimen at
the laboratory and field applied in this study.
CHAPTER 4 shows the detailed apparatus and test procedures at the laboratory
and field.
CHAPTER 5 investigates various factors on the strength and deformation
property of LSS prepared at field. A series of Consolidated-Undrained triaxial
compression tests with pore water measurement was carried out on the specimens curedin the field. And also, the in-situ compressive stiffness of LSS at field was evaluated byusing the PFWD method.
The effect of backfilling material on the building and ground under theearthquake is analyzed by using the FEM in CHAPTER 6. A three-dimensional model ofthe ground and construction was simulated in ABAQUS software. Three case studies withthree types of backfilling material: backfilling soil, LSS, and LSS with fiber wereanalyzed. Base on the analysis results, the effect of backfilling material on the building
and acceleration and velocity on the ground surface in each case were compared andinvestigated.
Finally, the main conclusions from the research are summarized in CHAPTER
7. The ideas and future works will also be recommended.

8

REFERENCES
Kuno, G., eds (1997): Liquefied stabilized soil method-Recycling technology ofconstruction-generated soil and mud, Gihodo publication (in Japanese).
Kohata, Y. (2006): Mechanical property of liquefied stabilized soil and future issues,
Doboku Gakkai Ronbunshuu, F, Vol.62, No.4, 618-627 (in Japanese).
Kohata, Y., Fujikawa, T., Ichihara, D., Kanda, M., and Murata, O. (2002): Strength anddeformation properties of fibered material mixed in liquefied stabilized soil
obtained from uniaxial compression test, Proc. of the 36th Japan National Conf.
on Geotech. Eng., pp.635-636 (in Japanese).
Kohata, Y., and Tsushima, H. (2004): Effect of fibered material mixing in liquefied
stabilized soil on the triaxial shear characteristics, Proc. of the 39th Japan
National Conf. on Geotech. Eng., 721-722 (in Japanese).
Kohata, Y., Ichikawa, M., Nguyen, C. Giang., and Kato, Y. (2007): Study of damage
characteristics of liquefied stabilized soil mixed with fibered material due totriaxial shearing, Geosynthetics Engineering Journal, Vol.22, 55-62 (inJapanese).
Ito, K., Kohata, Y., and Koyama, Y. (2011): Influence of additive amount of cement
solidification agent on mechanical characteristics of Liquefied Stabilized Soilmixed with fibered material, Japanese Geotechnical Society Hokkaido Branch
Technical Report Papers, Vol.51, 131-136 (in Japanese).
Do T. A and Kohata Y., Reduction of vehicle-induced vibration using liquefied stabilized
soil, International Journal of GEOMATE, 2019, Vol. 16, Issue 53, pp.44-46.

9

CHAPTER 2OVERVIEW OF LIQUEFIED STABILIZED SOIL

2.1.

INTRODUCTION
The purposes of Soil stabilization are improving the soil's strength andincreasing resistance to softening by water through bonding the soil particles together,waterproofing the particles, or a combination of the two (Sherwood, 1993). The simplest
stabilization processes are compaction and drainage (if water drains out of wet soil, it
becomes stronger). The other process is by improving the gradation of particle size, andfurther improvement can be achieved by adding binders to the weak soils (Rogers et al.,1993). Several methods can accomplish soil stabilization as following.
o Mechanical stabilization: soil stabilization can be achieved through the physicalprocess by altering native soil particles' physical nature by either induced
vibration or compaction or by incorporating other physical properties such as
barriers and nailing.
o Chemical stabilization: soil stabilization depends mainly on chemical reactions
between stabilizer (cementitious material) and soil minerals to achieve the desired
effect. Through soil stabilization, unbound materials can be stabilized withcementitious materials (cement, lime, fly ash, blast furnace slag, or a combinationof these).
“Liquefied stabilized soil” is a method of using chemical stabilization. The LSS
is mixed by the soil excavated from the construction project with binder and water. LSS
can be used for confined spaces or excavation areas, and it can be easily placed without
vibration and compaction. The advantages and applications of LSS have been shown,such as:o Advantages:
Easy placement
10Minimum settlement
Quick setting time
Ability to recycle
Low permeability
High strength
Protect the environment
Faster and more convenient than conventional backfilling
No need for a soil stockpile
Reduce the cost of construction projects
Reduce human resources
Reduction of vehicle-induced vibrationo Applications:
LSS as backfilling materials for transportation and construction works
Backfill using a concrete pump with a large distance and big volume
Cavities and excavated trenches can be backfilled easily without vibrationand compaction
2.2.

COMPONENT OF LIQUEFIED STABILIZATION SOIL
Liquefied stabilized soil focuses on using binder materials and fiber materials insoils to improve its geotechnical properties such as compressibility, strength, permeability,
flexibility, and durability. The components of liquefied stabilized soil include soils,
binders (cementitious materials), and water, as shown in Figure 2.1.

Figure 2.1 The components of Liquefied Stabilized Soil

11

2.2.1 Soil
Most soils in the liquefied stabilized soil method are soft soils. The stabilization
has been performed to achieve desirable engineering properties. The main purpose of theliquefied stabilized method is to recycle excavated soil for backfilling processes forconstruction projects. Therefore, almost types of excavated soils can be used for thismethod. However, fine-grained materials are the easiest to stabilize due to a large surface
area in their contact diameter. The excavated soils can be modified to perform mainlywith the purpose of improving their usability in construction. At present, excavated soils
are stabilized by binders which are selected with the type of soil. The stabilization has
improved the strength of the soils and their resistance to softening.
2.2.2 Cementitious materials
There are two kinds of binder material in the chemical stabilization method:
hydraulic (primary binders) and non-hydraulic (secondary binders) materials. When incontact with water or the presence of pozzolanic minerals, these binders react with water
to form cementitious composite materials. The commonly used binders are:Blast furnace slag
Lime
CementFly ashPozzolana
To decide which binder will be used, the analysis has been performed based on
test results and depend on the fact condition of projects.
2.2.2.1 Blast furnace slag
These are the by-product of pig iron production. The chemical compositions are
similar to that of cement. However, it is not a cementitious compound by itself, but it
possesses latent hydraulic properties which upon addition of lime or alkaline material thehydraulic properties can develop (Sherwood, 1993; Åhnberg et al, 2003). Depending on
the cooling system, Sherwood (1993) itemized slag in three forms, namely: air-cooledslag, granulated or pelletized slag, and expanded slag.
Air-cooled slag:
12

Hot slag after leaving the blast furnace may be slowly cooled in the open air,resulting in crystallized slag which can be crushed and used as aggregate.
Granulated or Pelletized slag:
Quenching (i.e. sudden cooling with water or air) of hot slag may result in theformation of vitrified slag. The granulated blast furnace slag or Merit 5000 (commonly
known in Sweden) is a result of the use of water during the quenching process, while, theuse of air in the process of quenching may result in the formation of pelletized slag.
Expanded slag:
Under certain conditions, steam produced during cooling of hot slag may giverise to expanded slag.
2.2.2.2 Lime
It was discovered that limestone, when burnt and combined with water, produced
a material that would harden with age. The earliest documented use of lime as aconstruction material was approximately 4000 B.C. when it was used in Egypt forplastering the pyramids. Until approximately 1900, lime putty was used in construction
applications. Limestone was burned in small kilns often built on the side of a hill tofacilitate loading. Wood, coal, and coke were used as fuel. The quicklime produced fromthese kilns was added to water in a pit or metal trough and soaked for an extended period.
The time required for soaking was dependent on the quality of the quicklime and could
range from days to years. It was generally thought that the longer the quicklime wassoaked, the better it would perform. The Standard Specification for Quicklime for
Structural Purposes was developed in 1913.
Lime is the oldest traditional stabilizer used for soil stabilization with the lowest
cost. Lime-treated soil was studied extensively in the literature. Numerous field andlaboratory studies were conducted to evaluate the improvement of geotechnical properties
by lime. Several types of soils, lime contents, and curing conditions and methodologies
were used for this purpose. The treatment mechanism comprised hydration, cationexchange, flocculation-agglomeration of soil particles, and pozzolanic reaction to form
Calcium Silicate Hydrate (C-S-H) and Calcium Aluminate Hydrate (C-A-H) as
cementitious materials.

The factors affecting lime-treated soil are lime content, curingtime, curing temperature, and soil mineralogy. Soil-lime mixtures have advantages anddisadvantages. Its advantages comprise increasing soil strength, reducing plasticity
13

(increase workability), and increasing soil durability. Besides, a considerable reduction inconsolidation settlement and improve compressibility characteristics were observed.
Unclear behavior was noted for the permeability of soil-lime mixture when comparedwith the original soil. Carbonation, sulfate attack, and environmental impact are a numberof the disadvantages of lime-treated soil. Some studies were conducted to provide someguidelines to reduce the deleterious effects of these cons. Magnesium oxide andhydroxide can be proposed as an alternative for lime since they possess chemical
characteristics that make them eligible to overcome the mentioned cons. Moreover, a few
conducted studies used magnesium-based additives to stabilize the soil was significantly
improved soil strength, workability, and durability. Therefore, it needs to conduct
extensive studies to determine the efficiency of this material in soil stabilization.
2.2.2.3 Cement
Cement had been known as the binding agent since the invention of soil
stabilization technology in the 1960s. It may be considered as a primary stabilizing agent
or hydraulic binder because it can be used alone to bring about the stabilizing action
required. Cement reaction is not dependent on soil minerals, and the key role is its reaction
with water that may be available in any soil. This can be the reason why cement is used
to stabilize a wide range of soils. Numerous types of cement are available in the market;
these are ordinary Portland cement, blast furnace cement, sulfate resistant cement, andhigh alumina cement. Usually, the choice of cement depends on the type of soil to betreated and the desired final strength.
The hydration process is a process under which cement reaction takes place. The
process starts when cement is mixed with water and other components for the desired
application resulting in hardening phenomena. The hardening (setting) of cement will
enclose soil as glue, but it will not change the structure of the soil. The hydration reaction
is slow proceeding from the surface of the cement grains and the Centre of the grains may
remain unhydrated. Cement hydration is a complex process with a complex series of
unknown chemical reactions. However, this process can be affected by the presence of
foreign matters or impurities, water-cement ratio, curing temperature, the presence ofadditives, and the specific surface of the mixture.
2.2.2.4 Fly ash

14Fly ash is a byproduct of coal-fired electric power generation facilities. It has
little cementitious properties compared to lime and cement. Most of the fly ashes belong
to secondary binders. These binders cannot produce the desired effect on their own.
However, in the presence of a small amount of activator, it can react chemically to forma cementitious compound that contributes to improved soft soil strength.
Fly ash has been used successfully in many projects to improve the strengthcharacteristics of soils. Fly ash can stabilize bases or subgrades, stabilize backfill to
reduce lateral earth pressures, and stabilize embankments to improve slope stability.
Typically stabilized soil depths are 15 to 46 centimeters. The primary reason fly ash isused in soil stabilization applications is to improve the compressive and shearing strengthof soils. The compressive strength of fly ash treated soils is dependent on:
In-place soil properties
Delay time
The moisture content at the time of compaction
Fly ash addition ratio
Class C fly ash can be used as a stand-alone material because of its selfcementitious properties. Class F fly ash can be used in soil stabilization applications withthe addition of a cementitious agent (lime, lime kiln dust, CKD, and cement). The selfcementitious behavior of fly ashes is determined by ASTM D 5239. This test provides a
standard method for determining the compressive strength of cubes made with fly ash andwater (water/fly ash weight ratio is 0.35), tested at seven days with standard moist curing.
The self-cementitious characteristics are ranked, as shown below:
Very self-cementing > 500 psi (3,400 kPa)
Moderately self-cementing 100 - 500 psi (700 - 3,400 kPa)
Non self-cementing < 100 psi (700 kPa)
It should be noted that the results obtained from ASTM D 5239 only
characterizes the cementitious characteristics of the fly ash-water blends and does notalone provide a basis to evaluate the potential interactions between the fly ash and soil oraggregate.
The use of fly ash in soil stabilization and soil modification may be subject tolocal environmental requirements about leaching and potential interaction withgroundwater and adjacent watercourses.
15

2.2.2.5 Pozzolana
Pozzolanas are siliceous and aluminous materials, which in itself possess little
or no cementitious value. However, in finely divided form and the presence of moisture,they will chemically react with calcium hydroxide at ordinary temperature to form
compounds possessing cementitious properties (ASTM 595). Clay minerals such as
kaolinite, montmorillonite, and mica are pozzolanic in nature. Artificial pozzolanas suchas ashes are products obtained by heat treatment of natural materials containing
pozzolanas such as clays, shales, and certain silicious rocks. Plants, when burnt, silica
taken from soils as nutrients remain behind in the ashes contributing to the pozzolanicelement. Rice husk ash and rice straw and bagasse are rich in silica and make an excellent
pozzolana (Sherwood, 1993).
2.2.3 Fiber materials
Nowadays, the constructions of buildings and other civil engineering structures
on weak or soft soil are highly risky because such soil is susceptible to differential
settlements, poor shear strength, and low compressibility. Various soil improvement
techniques have been used to enhance the engineering properties of soil. The idea ofreinforcing soils using fibers is one that has been in use for a long time. Initialdevelopments in soil reinforcement led to plant roots and straws in walls made from soil
bricks to improve their mechanical properties. Soil reinforcement by fiber material isconsidered an effective ground improvement method because of its cost-effectiveness,easy adaptability, and reproducibility. Many previous studies apply fiber materials toreinforce the soil, such as newspaper fiber, coir fiber, papyrus fiber, polypropylene fiber,and flax fiber.
2.2.3.1 Newspaper fiber
In 2002, Kohata et al. were proposed the LSS mixed the pulverized newspaper(Figure 2.2) as fiber material to improve the brittle mechanical property and to increase
the ductile performance of liquefied stabilized soil. It was shown that the ductile propertyof LSS mixed with pulverized newspaper as a fiber material after the peak in the q~εacurve was significantly improved by the reinforcement method (Kohata 2006; Kohata etal. 2004 and 2007; Ito et al. 2011).

16

Figure 2.2 Fiber material was made by the newspaper
2.2.3.2 Coir fiber
Coir fibers are categorized in two ways (Khan, 2007; Gu, 2009). One distinction
is based on whether they are recovered from ripe or immature coconut husks. The husks
of fully ripened coconuts yield brown coir. Dark brown in color, it is used primarily inbrushes, floor mats, and upholstery padding. On the other hand, white coir comes fromthe husks of coconuts harvested shortly before they ripen. Generally, light brown or whitein color, this fiber is softer and less strong than brown coir fiber. The coir fibers wereshown in Figure 2.3.
All of the published papers have generally shown that the addition of coir fiber
reinforced soil significantly increases the strength and stiffness as well as ductility of soils,
contributing to fiber characteristics such as tensile strength and modulus of elasticity.
Direct shear tests, unconfined compression tests, flexural strength, tensile strength, andtriaxial compression tests have demonstrated that the mechanical properties and shear
strength are increased with the addition of coir fibers in soils. The bond strength andfriction at the interface between fiber and soil grains are to be the dominant mechanism
controlling the reinforcement benefit. The main factors which affect the addition between
the reinforcing fibers and soil are the cohesive properties of soils and the shear resistanceof the soil due to the surface form and roughness of the coir fibers. Thus, using coir fiberin the soil is an effective reinforced soil technique in the geotechnical engineering field(Anggraini, 2016).
17

Figure 2.3 Coir fiber
2.2.3.3 Papyrus fiber
Papyrus has a wide range distribution in swamps, streams, lakes, and wetlands.
The mineral composition of papyrus differs in different parts of the plant. This variationin mineral composition is probably related to differences in the age of various portions
and differences in nutrient percentage (Gaudet, 1975). The papyrus fibers were shown in
Figure 2.4.
Direct shear, consolidation, and displacement tests were performed on papyrus
reinforced specimens with various fiber contents. These tests' results have clearly showna significant improvement in the failure deviator stress and shear strength parameters (cand ϕ) of the studied soil with a percent addition of 10% (the preferred percent). Moreover,this addition ratio reduced the displacement of the soil under loading. It can be concluded
that papyrus fiber can be considered an appropriate soil reinforcement material (AL-Adili
et al., 2012).

Figure 2.4 Papyrus before drying and crushing (a) and after treatment and sieving (b)18

2.2.3.4 Polypropylene fiber
The polypropylene fiber, also known as polypropene or PP, is a synthetic fiber,transformed from 85% propylene and used in various applications (Figure 2.5). One of
its applications is for the soil reinforcement method.
Tests were conducted on fiber-reinforced soil specimens with different
polypropylene fiber contents and compacted at different water contents and dry densities.
The tensile test results showed that fiber inclusion significantly increased the soil peakstrength, reduced the post-peak strength, and changed the brittle tensile failure behavior
to a more ductile one. Soil tensile strength increased with the increase in fiber content.
The tensile strength of both reinforced and unreinforced specimens decreased withincreasing water content and increased with increasing dry density. Moreover, a higher
soil dry density showed a more positive effect in mobilizing fibers' reinforcement benefit.
Based on the fiber/soil interfacial interaction mechanisms, the fiber reinforcement
benefits on soil tensile behavior were analyzed. A linear relationship was obtained
between the fiber reinforcement benefit and the fiber/soil interfacial shear strength. The
desiccation test results showed that fiber inclusion significantly decreased soil cracking.
The surface crack reduction ratio increased while the average crack width and length
decreased with increasing fiber content, suggesting that fiber reinforcement was efficientin impeding soil tensile failure (Chao et al., 2016).

Figure 2.5 Polypropylene fiber
2.2.3.5 Flax fiber and bamboo strip
Flax (Linum usitatissimum), also known as common flax or linseed, is a memberof the genus Linum in the family Linaceae. It is a food and fiber crop cultivated in cooler
19regions of the world. Textiles made from flax are known in Western countries as linen
and are traditionally used for bed sheets, underclothes, and table linen. Its oil is known aslinseed oil. In addition to referring to the plant itself, the word "flax" may refer to thefibers of the flax (Figure 2.6). Bamboos are of notable economic and cultural significancein South Asia, Southeast Asia, and East Asia, being used for building materials, as a foodsource, and as a versatile raw product. Bamboo, like wood, is a natural composite material
with a high strength-to-weight ratio useful for structures. Fresh bamboo is also used as apile to reinforce the ground in flooded conditions.
To study the mechanical properties of bamboo strips and flax fiber-reinforced
clay, a series of tensile tests were carried out by Fang et al. (2019) to obtain therelationship between the average tensile force and deformation of flax fiber and bamboo
strip; after that, triaxial shear tests were carried out under the conditions of different
confining pressures. Besides, the reinforcement mechanism of the bamboo strips and flax
fiber-reinforced clay is analyzed. Test results show that the bamboo strips' cohesion andinternal friction angle and flax fiber-reinforced clay are improved compared with the pureclay. In flax fiber-reinforced clay, reinforced clay's cohesion is increased by 18.34%, andthe friction angle is only increased by 0.39%. In bamboo strips and flax fiber-reinforced
clay, the cohesion of reinforced clay is increased by 26.36%, and the friction angle is only
increased by 10.24%. The addition of bamboo strips improves the shear strength of thereinforced clay and effectively improves the flax fiber-reinforced clay's deformation
resistance. And it increases the internal friction angle and cohesion of the clay, although
the increase in the strength is mainly reflected in the influence on the cohesion. This is aneffective method for reinforced soil.

Figure 2.6 Flax fiber (a) and bamboo strip (b)

20

2.3.

HISTORICAL DEVELOPMENT
The original concept comes from the United States. Soil mixing was firstdeveloped by Intrusion-Prepakt, Inc. of Cleveland, Ohio (Liver et al., 1954) as “Intrusion
Grout Mixed-in-Place Piles.”In 1961, the mixed in place was already used under license for more than 300
000 lineal meters of piles in Japan for excavated support and groundwater control.
Continued until the early 1970s by Seiko Kogyo Company, to be suggested by diaphragmwalls and deep mixing method (Soil-Mix Wall). Besides, Herrin and Mitchen (1961)
suggested that there is no one of optimum lime content with which maximum strength oflime stabilized soils can be expected under all conditions. For a specific condition of
curing tine and soil type, an optimum lime content that caused a maximum strength exists.
The development and research on deep mixing started from laboratory model
tests in 1967 by the Port and Harbour Research Institute of the Japanese Ministry ofTransportation. The research was continued by Okumura, Terashi, et al. through the 1970s,
including 1- investigation of lime-marine reaction, and 2- develop appropriate mixing
equipment. Unconfined compressive strength (UCS) of 0.1 to 1 MPa was achieved. Early
equipment (Mark I-IV) used the first marine trial near Hamada Airport (10 m below thewater surface). The Swedish Lime column method for treating soft clays underembankment using unslaked lime was researched (Kjeld Paus, Linden- Alimak AB, in
cooperation with Swedish Geotechnical Institute, Euros AB, and BPA Byggproduction
AB). And then, this follows observations by Paus on fluid lime column installation in the
United States.
In the late 1960s, China reported being considering implementing the Depp lime
mixing concept from Japan.
Development of Soil Mixed wall method for retaining walls, using overlap
multiple augers, was started in Japan by Seiko Kogyo Co. of Osaka in 1972 to improvelateral treatment continuity and homogeneity/quality of treated soil.
The first Japanese full-scale Deep Mixing project was conducted in 1974. First
applications in reclaimed soft clay at Chiba (June) and applications elsewhere in
Southeast Asia follow the same year. Besides, intensive trials were conducted with Lime
Columns at Ska Edeby Airport, Sweden: basic tests and assessment of drainage action(columns 15 m long and 0.5 m in diameter). In 1974, the first detailed description of theLime Column method by Arrason et al. (Linden Alimak AB). And the first similar trial
21

embankment using the Swedish Lime Column method in soft clay in Finland (6 m high,8 m long; using 500-mm-diameter lime cement columns, in soft clay) in 1974.
In 1975, deep mixing’s first appearance in an international forum in Bangalore,
India, a Swedish paper on Lime Colum by Broms and Boman. Also, a Japanese paper on
Deep Lime Mixing (DLM) by Okumura and Terashi was presented to the Swedish paperon lime columns (Broms and Boman), and a Japanese paper on DLM (Okumura andTerashi) presented at the same conference in Bangalore, India. Both countries had
proceeded independently to this point. Limited technical exchanges occur thereafter.
Following their research from 1973 to 1974, PHRI develops the forerunner of the Cement
Deep Mixing (CDM) method using fluid cement grout and employing it for the first timein large-scale projects in soft marine soils offshore. (Originally similar methods include
DCM, CMC (still in use from 1974), closely followed by DCCM, DECOM, DEMIC, etc.,
over the next five years). The first commercial use of the Lime Column method in Sweden
for support of excavation, embankment stabilization, and shallow foundations near
Stockholm (by Linden Alimak AB, as contractor and SGI as consultant/researcher) in1975.
Public Works Institute Ministry of Construction, Japan, in conjunction with theJapanese Construction Machine Research Institute, began research on the Dry Jet Mixing(DJM) method using dry powdered cement (or less commonly, quick-lime) in 1976. It
was also the same year that Soil Mixed Wall (SMW) method was used commercially forthe first time in Japan by Seiko Kogyo Co.
In 1977, Cement Deep Mixing (CDM) method had been marked development.
CMD method Association was established in Japan to coordinate technologicaldevelopment via a collaboration of industrial and research institutes and the first practicaluse of CMD (marine and land use). First design handbook on lime columns (Broms andBoman) published by Swedish Geotechnical Institute. China commences research into
CDM, with first field application in Shanghai using its land-based equipment in 1978.
The first commercial using in Japan of Dry Jet Mixing was marked in 1980, andthen it quickly superseded Deep Lime Mixing (DLM) with land-use only. Besides, DJM
Association was established in Japan. In 1983, Eggestad published a state-of-the-art
report in Helsinki dealing with new stabilizing agents for the Lime Column method.
In 1984, the SWING method developed in Japan, followed by various related
jet-assisted (W-R-J) methods in 1986, 1988, and 1991.

22

The Tenox Company reported more than 1000 projects completed with the SCC
method in Japan (1989), prior to major growth thereafter (9000 projects to end of 1997,
with a $100 to 200 million/year revenue in Japan and elsewhere in Southeast Asia). In
1990, Dr. Terashi, involved in the development of DLM, CDM, and DJM since 1970 at
Port and Harbor Research Institute, Japan, gives November lectures in Finland.
Introduces more than 30 binders commercially available in Japan, some of which containslag and gypsum as well as cement. Possibly leads to the development of “secret reagents”
in Nordic Countries thereafter.
Low Displacement Jet Column Method (LDis) was developed in Japan in 1991.
In the same year, the Bulgarian Academy of Sciences reports local soil-cement research
results, and the Geotechnical Department of City of Helsinki, Finland, and contractor YIT
introduce block stabilization of very soft clays to depths of 5 m using a variety of different
binders.
In the early 1990s, the First marine application of CDM at Tiajin Port, China:
designed by Japanese consultants (OCDI) and constructed by a Japanese contractor withhis equipment (Takenaka Doboku).
In 1991, the Chinese Government (First Navigational Engineering Bureau of
Ministry of Communications) built the first offshore CDM equipment “fleet,” using
Japanese technology used for the first time (1993) at Yantai Port. (Reportedly the firstwholly Chinese Design-Build DMM project.). And Jet and Churning System
Management (JACSMAN) developed by Fudo Company and Chemical Grout Company
in Japan.
DJM Association Research Institute published updated Design and Construction
Manuals (in Japanese) in 1993. In the same year, CDM Association claims 23.6 million
m3 of soil treated since 1977. And SMW claims 4000 projects completed worldwide since
1976, comprising 12.5 million m2 (7 million m3). According to a Japan report, from 1977
to 1995, more than 26 million m3 of CDM treatment reported and about 15 million m3
of DJM treatment.
In 1997, the SMW method was used for massive ground treatment projects at
Fort Point Channel, Boston, MA (largest DMM project to date in North America), andother adjacent projects. Input at the design stage to U.S. consultants by Dr. Terashi (Japan).
From 1998 to around the year 2000, a variety of numerical modeling work has
been performed on the interaction of soil-cement columns in soft clays, for example,
Kerin and Karstunen (2009), Chai et al. (2010) and Abushara et al. (2009). Their studies
23

have focused on settlement reduction from “T” shaped columns, “cross” shaped columns,
and “multi-columns” supported embankment loading.
Historical development of LSS in Kohata's laboratory
Kohata et al., (2002) were proposed the LSS mixed the pulverized newspaper asfiber material in order to improve the brittle mechanical property and to increase theductile performance of LSS. It was shown that the ductile property of LSS mixed withpulverized newspaper as a fiber material after the peak in the q~εa curve was significantly
improved by the reinforcement method (Kohata 2006; Kohata et al. 2004 and 2007; Itoet al. 2011).
In 2010, Nguyen et al., performed experiments with both LSS using NSF-Clay(NSF-Clay is fine powder clay bought in the Japanese market) and Vinh Phuc-Clay(excavated soil spread in Hanoi area) as original material. The relationship between
deviator stress q (=σ1-σ3) and axial strain εa from Consolidated–Undrained triaxial
compression tests under confining pressure σ′c = 98 kPa of Vinh Phuc-Clay LSS and
NSF-Clay mixed by fibered material content of 0, 10, 20 kg/m3 at 56 days, respectively
was established. The tests were performed under an axial strain rate of 0.054 %/ min. The
results of the research indicated that the physical behaviors of both LSS tend to be similar.
The previous research in 2015 investigated the time-dependency on shear
deformation characteristics of LSS using NSF-clay mixed by fiber material contents of 0,
20 kg/m3. On the other hand, the target density of slurry of 1.280 g/cm3 was selected. A
series of Undrained triaxial compression tests under confining pressure σ′c = 98 kPa had
been performed with four different conditions of axial strain rate (Duong, 2015). The
specimens had been cured under indoor and outdoor conditions. The research results
indicated that: Firstly, the maximum deviator stress, qmax in q~εa curve of LSS mixed
with fibered material indicates similar value independently of curing days. However, inthe case of LSS without fibered material, there is a tendency to increase the initial stiffness
as increasing of curing days; Secondly, the range of indicating Etan/E0 value of 1.0 tends
to be larger on LSS mixed with fibered material. This is due to the reinforcing effect of
the fibered material in LSS; Thirdly, the rigidity during loading before the peak in q~εa
relationship increases temporarily in a large strain level after a creep stage and a changeof strain rate independently of curing day; Finally, a procedure for predicting traininduced vibration from railway tunnels in conformity with the condition of Vietnam has
been established as an example for Hanoi metro line. The vibration propagation from thetunnel into the ground surface was analyzed by the two-dimensional element method (224

D FEM). The established procedure was then used to evaluate train-induced vibration as
using LSS for backfilling ground of cut and cover tunnel. The results have shown that the
LSS could reduce train-induced vibration from the tunnel.
In 2019, research works including experiments and analyses had been conductedsimultaneously, aiming to promote the application of LSS in the future (Do, 2019). The
influence of slurry density on strength and deformation characteristics of LSS mixed withfibered material was evaluated. A series of Consolidated–Undrained triaxial compression
tests with measured pore water (CUB tests) under the condition on an axial strain rate of
0.054 %/ min have been carried out for LSS mixed with fiber material amount of 0 and
10 kg/m3 at curing time of 28 and 56 days, respectively. Based on the test results, it was
found that when the slurry density is slightly decreased from the appropriate slurry density,
it is considered that the maximum deviator stress (qmax) decreased remarkably. In addition,
it was found that the local damage caused by shearing even in the LSS mixed with fiber
material prepared on the low slurry density is reduced by the effect of reinforcement on
the fiber material. On the other hand, the difference in triaxial shear property of LSS
mixed with fiber material cured in the laboratory and at field was investigated to be
carried out a series of CUB tests for both specimens of LSS mixed with fiber material
amount of 0 and 10 kg/m3 prepared by trimming LSS retrieved from a model ground byblock sampling and cured in the laboratory at curing time of 28 and 56 days, respectively.
Based on the test results, it was found that the qmax in q~a relations of LSS mixed withfiber material cured at field tends to be larger than that cured in laboratory. Besides,
according to the numerical analysis results on mitigation of vehicle-induced vibration incase using LSS as backfill material by the established analysis method, it is found that theapplication of LSS can reduce the ground vibration.
The research in 2020 investigated the influence of reducing slurry density while
preparing the LSS specimens with different cement content mixed with fibers (Yujie Cui,2020). A series of triaxial compression tests and unconfined compression tests wereconducted on LSS specimens prepared in different slurry densities of 1.216, 1.280 g/cm3,
cement contents 80, 100 kg/m3, and the fiber contents of 0, 10kg/m3 with different curing
time of 28 and 556 days, respectively. The results showed that a slight decrease in slurry
density could decrease the peak stress of LSS remarkably. Meanwhile, the change incement content can affect peak strength and the decreasing rate of Etan/ E0 in the earlyloading stage. Besides, by adding fiber material, the local damage caused by shearing andthe brittleness were improved.
25

2.4 APPLICATIONS OF LIQUEFIED STABILIZED SOIL IN CONSTRUCTION
In the 1990s, Kuno et al. presented one of the LSS method applications, fillinga cavity under the pavement of an urban road (Figure 2.7). The cavity is inferred mainly
because the submerged backfilled sand in the ground is washed out little by little to a
nearby open space, for example, sewage pipes, and thus, a cavity is created grown. Thisapplication is thought to be possible of decreasing time and cost comparing to aconventional method. Thus, two kinds of field performance tests were conducted to verify
the method's capability and applicability and acquire necessary field data for future
maintenance works. The first field performance test used an on-site plant and a stabilized
soil of low strength and relatively high flow condition, while the second test uses a remoteplant and stabilized soils of high strength and low flow condition. The tests were
evaluated in terms of adequate mix proportion, working system, working time, fillingoutcome, occupation of road, quality control test, and so on. Through two sequential field
performance tests, it is confirmed that the method possesses the good capability of filling
cavities under the pavement and makes it possible to decrease time and cost.

Figure 2.7 Use of LSS for filling the cavity under the road surface
Murata (2011) reported that LSS consists of the slurry made of on-site soil, water,
cement, and sand of clay as appropriate LSS is used for backfill at the upper part of a cut
and cover tunnel and as an invert material of a shield tunnel (Figure 2.8 and Figure 2.9).
Pit sand is usually used for backfill, but LSS is much better than the sand because it iseasy to use with on-site soil, and LSS can be buried without compaction into a narrow
space. The lower part of the shield tunnel is usually buried by low-strength concrete26

(unconfined compressive strength: about 10 MN/m2). However, from the environmental
point of view, LSS, which can reuse on-site soil, is now often used. A mixture of LSS
was designed from the results of unconfined compressive tests and repeated loading tests.
Then, it was designed the unconfined compressive strength of liquefied soil should be 6
MN/m2 for safety purposes. To hold this strength level for some on-site soil, a hugeamount of cement is needed (300 ~ 400 kg/m3 of LSS). So, a method to mix wasted fiber
materials into LSS has been studied to increase the strength and ductility and decrease thetotal material cost. Studied have been promoted on what types of wasted fiber material
are available and what rigidity level of wasted fiber material is needed.

Figure 2.8 LSS used for backfill at the

Figure 2.9 LSS used for invert material ofupper part of the cut and cover tunnel

shield tunnel

The strength and quality control method of LSS used as a building foundation is
proposed by Tomoharu et al. (2005) (Figure 2.10). The research results pointed out that
it is feasible for LSS to apply for the building foundation from a future perspective.
Another application of LSS is for constructing fences or retaining walls. Yoshihiro et al.
(2006) reported that concrete block construction is common for these structures, tens tocollapse under strong earthquakes, causing a threat to traffic. In contrast, liquefied
stabilized soil block construction can avoid such damage due to the greater toughness ofthe material. Also, soil blocks are advantageous over concrete blocks in terms ofappearance. Their research has examined the effects of adding PVA fiber to LSS blocks
27

under atmospheric conditions. Tests were carried out on the drying shrinkage properties,
resistance to atmospheric exposure, and uniaxial compressive strength. It found that PVA
fiber reduces the drying shrinkage, crack propagation, and compressive strength of the
LSS block. The following Figure 2.11 is more examples of using LSS for various
backfilling works in Japan.

Figure 2.10 Flow of Liquefied soil stabilized method

Figure 2.11 Using LSS for various backfilling works in Japan; (a): backfilling ofbuilding foundation; (b): backfilling of the underwater seawall; (c): backfilling of
abutment; (d): backfilling of box culvert; (e): backfilling of the underground pipe; (f):filling of underfloor due to subsidence
28

Recently, most underground pipelines have been backfilled by LSS (Figure 2.11e). Figure 2.12 shows a construction site of the pipelines using LSS. Kawabata et al.
(2008) conducted a full-scale field test for a buried pipe using a steel pipe of 3500 mmdiameter and 26 mm-thickness. Five cases of backfilling methods were applied. From thetest results, it was found that the stiffness of the backfilling method strongly influenced
the behavior of the buried pipe. In particular, the pipe which is backfilled with LSS
showed stable behavior. Moreover, Kashiwaghi et al. (2009) and Kawabata et al. (2010)
have proposed a thrust restraint method using LSS. Model pit experiments using a model
pipe with a diameter of 260 mm were carried out to examine the effectiveness of the LSS
for the thrust restraint of buried bend. LSS was applied to the model pipe's passive area,and dry silica sand was used as backfill material. The model pipe was laterally loaded at
a 1 mm/min speed after backfilling to simulate the thrust force. The lateral resistance andhorizontal displacement of the model pipe were both measured. The earth pressure
distributions of the passive ground were observed. The results showed that the lateralresistance of the bend in using LSS was increased. It is verified that LSS is an effective
backfill material for thrust restraint. Other experimental research results showed that thebending stiffness in case using LSS with geosynthetics was increased (Kawabata et al.,2009). Besides, passive resistance was considerably increased in the case of using LSS
with geogrid (Kawabata et al., 2008).

Figure 2.12 Backfilling of LSS
Another method is the pipe-line soil treatment system (Figure 2.13). For
stabilization of dredged mud, pipe-line soil mixing methods are getting popularized in
29

Japan. The pipe-line treatment system has developed as a kind of pipe-line soil mixing
method. The system is called “Kanro Mixer” installed on the way of dredging pipe-line
and feeder devices for mixing materials. The system can be utilized for not only the
consolidation of mud but also making the foam mixed soil, producing grainy soil, and soon (Miki et al., 2005).

Figure 2.13 Production system for foam mixed lightweight soil
Backfill as a seep-proof structure: To protect the dredgings or waste soils fromleaking through the rubble mound, it is necessary to place protection inside the wharf. It
was found that dredged soft soil after being treated with cement was a rational alternative
for this protection at a depth of 20 to 40 m (Tang et al., 2001). As shown in Figures 2.14
and 2.15, it was decided to place the cement-treated soil inside the wharf, with a layer
thickness greater than 1.0 m and a slope about 1:3.

Figure 2.14 Cement treated soil using as slope protection

30

Figure 2.15 Placement of cement-treated soil along slope

31

REFERENCES
Sherwood, P. (1993). Soil stabilization with cement and lime. State of the Art Review.
London: Transport Research Laboratory, HMSO.
Rogers, C.D.F., and Glendinning, S. (1993). Modification of clay soils using lime. In C.
a. Rogers (Ed.), Proceeding of the Seminar held at Loughborough University on
Lime Stabilization (pp. 99-114). London: Thomas Telford.
Kohata Y, Fujikawa T, Ichihara D, Kanda M and Murata, O., Strength and deformation
properties of fibered material mixed in liquefied stabilized soil obtained fromuniaxial compression test, Proc. of the 36th Japan National Conference on
Geotechnical Engineering, 2002, pp.635-636 (in Japanese).
Kohata, Y. (2006). Mechanical property of liquefied stabilized soil and future issues,
Doboku Gakkai Ronbunshuu, F, Vol.62, No.4, pp.618-627 (in Japanese).
Kohata, Y., and Tsushima, H. (2004). Effect of fibered material mixing in liquefied
stabilized soil on the triaxial shear characteristics, Proc. of the 39th Japan
National Conf. on Geotech. Eng., pp.721-722 (in Japanese).
Kohata, Y., Ichikawa, M., Nguyen, C. Giang., and Kato, Y. (2007). Study of damage
characteristics of liquefied stabilized soil mixed with fibered material due totriaxial shearing, Geosynthetics Engineering Journal, Vol.22, pp.55-62 (inJapanese).
Ito, K., Kohata, Y., and Koyama, Y. (2011). Influence of additive amount of cement
solidification agent on mechanical characteristics of Liquefied Stabilized Soilmixed with fibered material, Japanese Geotechnical Society Hokkaido Branch
Technical Report Papers, Vol.51, pp.131-136 (in Japanese).
Khan, B. A. (2007). Uses of coir fiber, its products & implementation of geo-coir in
Bangladesh.
Gu, H. (2009). Tensile behaviours of the coir fibre and related composites after NaOH
treatment. Materials & Design, 30(9), 3931-3934.
Anggraini, Vivi. (2016). Potential of Coir Fibres as Soil Reinforcement. The Pertanika
Journal of Scholarly Research Reviews. 2. 95-106.
Gaudet, J.J. 1975, Mineral Concentrations in Papyrus in Various African Swamps, J. Ecol.,63, No. 2, 483-491.
32

AL-Adili, Aqeel & Azzam, Rafig & Spagnoli, Giovanni & Schrader, Joerg. (2012).
Strength of soil reinforced with fiber materials (Papyrus). Soil Mechanics andFoundation Engineering. 48. 10.1007/s11204-012-9154-z.
Chao-Sheng Tang, De-Yin Wang, Yu-Jun Cui, Bin S. (2016). Tensile Strength of FiberReinforced Soil. Journal of Materials in Civil Engineering, Vol. 28, Issue 7.
Fang Tong, Qiang Ma, Wenwen Xing, "Improvement of Clayey Soils by Combined
Bamboo Strip and Flax Fiber Reinforcement", Advances in Civil Engineering,
vol. 2019, Article ID 7274161, 10 pages, 2019.
Liver, Norman L., Mardorf, Erwin C., King, John C. (1954). “Development andApplications of Intrusion Grout Mixed-in-Place Piles”, Civil Engineering,
March 1954, 56-57.
Herrin, Moreland., Mitchell, Henry (1961). Lime-soil mixtures. 40th Annual Meeting of
the Highway Research Board. No 304, pp 99-138.
Okumura, T. and Terashi, M. (1975): Deep lime-mixing method of stabilization formarine clays. In: Proceeding of the 5th Asian Region Conference on Soil
Mechanic and Foundation Engineering, Bangalore, Vol.1, pp. 69-75.
Terashi, M., Tanaka, H. and Okumura, T. (1979): Engineering properties of lime treatedmarine soils and DMM. In: Proceedings of 6th Asian Regional Conference on
Soil Mechanics and Foundation Engineering, Vol.1, pp.191-194.
Terashi, M. (1983): Practice and problems of the deep mixing method of soil stabilization,
Soils, and Foundations, Vol. 31-8, pp.75-83.
Arrason, KG., B. Broms, S. Granhom, and K. Paus. (1974). Deep stabilization of softcohesive soils. Linden-alimak, Skelleftea.
Broms, B. B and P. Boman. (1975). Lime stabilized column. Proceedings, 5th AsianRegional Conference on SMFE, Vol. 1, pp. 227-234.
Broms, B. B and P. Boman. (1977). Stabilization of soil with lime column. Royal Instituteof Technology, Stockholm.
Eggestad, A. (1983). “Improvement of cohesive soils, state-of-the-art report.”
Proceedings of the Sth ECSMFE, Helsinki.
Takenaka Civil Engineering. (1995). “Deep chemical mixing method using cement as
hardening agent.” Published by Takenaka Corporation.
33

Chai, J.C., Hino, T., Igaya, Y. and Yamauchi, Y. (2011): Embankment construction withsaturated clayey fill material using geocomposites, Geotechnical Engineering
Journal of the SEAGS & AGSSEA, Vol.42 (1), pp.35-41.
Nguyen C. G (2010). Study on Advanced Effective Utilization of Excavation Soil In
Hanoi City – Vietnam. Phd thesis, Muroran Institute of Technology, Japan.
Duong Q. H (2015). Study on application to backfilling ground by Liquefied Stabilized
Soil mixed with fiber material in Hanoi city. Phd thesis, Muroran Institute ofTechnology, Japan.
Do T. A (2019). Study on promoting use of Liquefied Stabilized Soil mixed with fiberedmaterial as backfilling material in Hanoi city. Phd thesis, Muroran Institute ofTechnology, Japan.
Cui Y (2020). Study on strength and deformation property of Liquefied Stabilized Soilmixed with fibered material prepared under poor quality condition. Phd thesis,
Muroran Institute of Technology, Japan.
Kuno, G., eds (1997): Liquefied stabilized soil method-Recycling technology ofconstruction-generated soil and mud, Gihodo publication (in Japanese).
Kuno, G., Miki, H., Mori, N. and Iwabuchi, J. (1995); Study on backfilling method withliquefied stabilized soil as to recycling excavated soils, Individual papers 20th
world road congress, Montreal, Canada.
Kuno, G., Miki, H., Mori, N. and Iwabuchi, J. (1996); Application of the liquefied
stabilized soil method as a soil recycling system, Proc. The second international
congress on environmental geotechnic, Osaka, Japan.
Kuno, G., Okamoto, S. and Shibata, Y. (1998): Recycling excavated soil to back-fillingmaterial with liquefied stabilized soil method, Proc. CIB world building
congress, Gaevle, Sweden, 7-12 June 1998.
Kuno, G., Miki, H., Mori, N. and Iwabuchi, J. (1997); Filling a cavity under pavement ofurban road with liquefied stabilized soil, Road construction rehabilitation andmaintenance, XIII th IRF world meeting, Toronto, Canada.
Murata, O. (2011): Recent research and development on soil and foundation engineering
at Railway Technical Research Institute (Japan), QR of RTRS, Vol.42, No.3,
pp.122-124.

34

Tomoharu, O., Mitsuo, N., Hiroki, Y., Mamoru, F. and Hiroyuki, A. (2005): Liquefied
stabilized soil method for building foundation, Japanese Society of Material
Science, Japan, Vol.54, No.11, pp.1129-1134 (in Japanese).
Kawabata, T., Sawada, Y., Oguchi, K., Totsugi, A. Hironaka, J. and Uchida, K. (2007):
Large scale tests of buried bend with lightweight thrust restraint using
geosynthetics, ISOPE2007, Lisbon, Portugal.
Kawabata, T., Sawada, Y., Kashiwagi, A., Izumi, A. and Uchida, K. (2008): The effect ofliquefied stabilized soil with goesynthetics against thrust force of buried bend,
Proc. of the Eighteenth (2008) International offshore and Polar engineering
conference Vancouver, BC, Canada, July 6-11, 2008, pp.660-664.
Kawabata, T., Takafumi, H., Kashiwagi, A., Izumi, A. and Kada, M. (2009): Bending test
for liquefied stabilized soil with steel rebar, Proc. of the Nineteenth (2009)
International offshore and Polar engineering conference, Osaka, Japan, June 2126, 2009.
Kashiwagi, A., Kawabata, T., Satoshi, O. and Uchida, K. (2009): Evaluation of lateralresistance for buried conditions around pipe with horizontal loading, Proc. of the
Nineteenth (2009) International offshore and Polar engineering conference,
Osaka, Japan, June 21-26, 2009.
Kawabata, T., Kashiwagi, A., Sawada, Y., Okuno, S., Ling, H., and Mohri, Y. (2010):
Lateral Loading Experiment on Buried Pipe Using Liquefied Stabilized Soil as
Backfill Material for Thrust Restraint, ASCE Library, Pipelines 2010, pp.12441254.
Kawasaki, T., Niina, A., Saitoh, S., Suzuki, Y. and Honjo, Y. (1981): Deep mixing method
using cement hardening agent. In: Proceedings of 10th International Conference
on Soil Mechanics and Foundation Engineering, Stockholm, pp.721-724.
Miki, H., Iwabuchi, J. and Chida, S. (2005): New soil treatment methods in Japan.
Tang, Y. X. Miyazaki, Y. and Tsuchida, T. (2001): Practices of reused dredging by cement
treatment, Soils and Foundations, Vol. 41(5), pp.129-143.

35

CHAPTER 3
MATERIALS AND PREPARATION METHOD OF SPECIMEN

3.1 INTRODUCTION"Liquefied Stabilized Soil" (LSS) is one of the effective methods of using
excavated soil with construction works and has become popular in Japan (Kuno, 1997).
The LSS is a kind of cement-treated soil, which is prepared by mixing slurried soil andcement stabilizer. The LSS mixtures are not only created stabilized ground without
compaction but also easy to fill empty space by pumping a long distance. However,according to previous studies, it is shown that the increase in cement content does not
only increase the strength property but also the brittleness increases. Therefore, Kohata
et al. were proposed the LSS mixed the pulverized newspaper as fiber material in orderto improve the brittle mechanical property and to increase the ductile performance of LSS(Kohata et al. 2002). It was shown that the ductile property of LSS mixed with pulverizednewspaper as a fiber material after the peak in the q~εa curve was significantly improvedby the reinforcement method (Kohata 2006; Kohata et al. 2004 and 2007; Ito et al. 2011).
In order to study the strength and deformation properties of the LSS, a series oftest specimens were prepared. In this chapter, the test materials and the procedures ofmaking the sample will be detailed.
3.2 TEST MATERIALSThe samples of LSS, which were used for the experiment in the laboratory andfield, were mixed with the following ingredients: The New Snow Fine Clay, cement, fiber
material, and water.
3.2.1 The New Snow Fine Clay (NSF-Clay)In this study, the NSF-Clay (Figure 3.1) was used as a homogeneous basematerial, which is a commercially available cohesive soil with very clearly defined
physical parameters shown in Table 3.1.
36

Figure 3.1 The New Snow Fine Clay

Table 3.1 Physical parameters of NSF - Clay
Physical parameters

ValuesDensity of particle s (g/cm3)

2.762

Liquid limit WL (%)

60.15

Plastic Limit WP (%)

35.69

Plasticity Index IP

24.46

3.2.2 Cement
In this experiment, Geoset 200 cement provided by Taiheiyo Cement Co. waschosen as the binder (Figure 3.2). GEOSET 200 is a general-purpose soil stabilizer witha minimal level of hexavalent chromium leaching. It is suited for a wide variety of
purposes, including both shallow and deep stabilization of soft ground, as well as thesolidification of sludge and bottom-layer soil. It delivers the required unconfinedcompressive strength and California bearing ratio (CBR) through the appropriate settingof additive amounts for a wide variety of soil qualities.

37

Figure 3.2 Geoset 200 cement
3.2.3 Pulverized newspaper
The pulverized newspaper (Figure 3.3) was used as the fiber material, which wasmade by the following procedure. The newspaper was cut by the office shredder into
small pieces. The cut papers were mixed with water and pulverized by a food processor
for cooking. The paper was untied by the hand after dried in a drying oven. It was
pulverized again to smaller pieces like cotton by the food processor.

38

Figure 3.3 The pulverized newspaper
3.2.4 Water
The water used in the sample mixing must meet the clean water standards andbe taken directly from the municipal water source. Water will be calculated at a certain
percentage to produce the desired density of the LSS mixture.
3.3 MIXING METHOD
The slurry type and the adjustment slurry type are two LSS mixing methods,
which are the common mixing methods for recycling excavated soil. The slurry type waschosen for this study because it prepares easier than the adjustment slurry type.
In the previous research, various mixing tests were conducted to adjust the slurry
density and the amount of cement stabilizer. The bleeding rate, flow value, andunconfined compressive strength were investigated by soil tests corresponding to eachparameter for each of LSS at the curing time of 28 days (Ito et al. 2011; Duong et al.
2014). Based on these tests, the standard slurry density was decided for this study, as
shown in Figure 3.4.

39

Figure 3.4 Available range of slurry density
Firstly, an appropriate amount of water was added and mixed with NSF - Clay,then the density of slurry was adjusted, after that the cement stabilizer was added andmixed. Finally, the pulverized newspaper will be put into the mixture with a calculated
rate and mixed carefully. The LSS mixture is finished. The detailed steps will be shownas follows:
Step 1: Put the bucket on the scale, weigh the bucket, write down the value ofthe bucket, and then set the value of the scale to zero.

Figure 3.5 Bucket and electronic scale
Step 2: Based on the number of samples required, preliminary calculations of
the amount of water need to mix with soil. Input water into bucket, weigh it and write
40

down the value.
Step 3: Based on the amount of water in the bucket and the LSS mixture's density,
we can calculate approximately the amount of NSF - Clay needs to mix with water. Then,adding clay into the water. When adding clay, do not put them on the wall of the bucket.
Step 4: The mixture was carefully mixed by hand mixer (Figure 3.6). After that,
put the slurry into a stainless steel container of 400 cm3 called "AE mortar container" tocheck its density (Figure 3.7). If there is too much difference from the target value of
density, add clay or water again to adjust the density until it reached the target value of
density.

Figure 3.6 NSF-Clay and water were mixed in the bucket by hand mixer

Figure 3.7 The density of the mixture was checked by AE mortar container
41

Step 5: After the density of slurry reached the target value, using the calculation
form to show the amount of cement needs to be add.Then add cement and mix them fully
with the hand mixer.
Step 6: After adding the cement, put the mixture into a sealed container for
degassing (Figure 3.8). Open the main switch of negative pressure, link to the container,
and open valves. Turn the negative pressure to - 98 kPa and set the time to an hour. Afteran hour of degassing, reduce the pressure, close the valves, and weigh the bucket (thebucket must be washed and drying at this moment and weigh).

Figure 3.8 Sealed container for removing air bubbles

Step 7: Pour the measured sample material back into the bucket and weightogether.
Step 8: Based on the proportion of fiber material and volume of the mixture, wewill calculate the amount of fiber to be added to the mixture. Put the fiber into the mixture
and mix slowly and evenly with a hand mixer. Check the density of LSS with fiber
material.

423.4 SPECIMEN PREPARATION
3.4.1 Preparation method of the specimen at laboratory
To prepare the laboratory sample, the mixture of LSS with fiber material will befilled into the plastic boxes, as shown in Figure 3.9. When half-filled, slightly shake theair bubbles at the bottom of the box to escape out. Continue to fill the other half of thebox and shake for a second time. After the sample is full of mixture, cover the wholesample with thin plastic, and tie it with rubber bands. Finally, put the sample into a big
container with constant temperature and humidity (Figure 3.10). After the desired numberof curing days, remove the sample from the box and weigh the sample (Figure 3.11). Be
careful when removing the sample to avoid the sample being chipped or cracked affectthe test results.

Figure 3.9 Plastic box

Figure 3.10 Curing specimen
43

Figure 3.11 The mass of the sample was checked
3.4.2 Prepared method of the specimen at field
For making samples in the field, two pits were excavated at the test field on thecampus, as shown in Figure 3.12. A nonwoven geotextile filter was set to prevent the
seepage of the mixture to the ground. The mixture of LSS and fiber material was filled
up two pits, and the surface was covered with a polymer sheet and cured under nature
condition (Figure 3.13).

Figure 3.12 Schematic drawing of pits and specimen at the test field44

Figure 3.13 Curing sample under the nature condition
To accurately determine the curing temperature of the sample under natural
conditions, a temperature sensor has been installed in the excavation hole in the field of
the campus, as shown in Figure 3.14. The temperature in the sample will be measured forhours, and the data will be transmitted to the data receiver. After a calculated curing time,
the samples prepared by trimming LSS retrieved from the test field were subjected to
CUB tests, as shown in Figure 3.15. In parallel, the model ground was subjected toportable Falling Weight Deflectometer (PFWD) tests.

Figure 3.14 Temperature sensor installed in the excavation hole45

Figure 3.15 The samples prepared by trimming LSS retrieved from the test field

46

REFERENCES
Kuno G., Liquefied stabilized soil method- Recycling technology of constructiongenerated soil and mud, Gihodo publication, 1997 (in Japanese).
Kohata Y, Fujikawa T, Ichihara D, Kanda M and Murata, O., Strength and deformation
properties of fibered material mixed in liquefied stabilized soil obtained fromuniaxial compression test, Proc. of the 36th Japan National Conference on
Geotechnical Engineering, 2002, pp.635-636 (in Japanese).
Kohata, Y. (2006). Mechanical property of liquefied stabilized soil and future issues,
Doboku Gakkai Ronbunshuu, F, Vol.62, No.4, pp.618-627 (in Japanese).
Kohata, Y., and Tsushima, H. (2004). Effect of fibered material mixing in liquefied
stabilized soil on the triaxial shear characteristics, Proc. of the 39th Japan
National Conf. on Geotech. Eng., pp.721-722 (in Japanese).
Kohata, Y., Ichikawa, M., Nguyen, C. Giang., and Kato, Y. (2007). Study of damage
characteristics of liquefied stabilized soil mixed with fibered material due totriaxial shearing, Geosynthetics Engineering Journal, Vol.22, pp.55-62 (inJapanese).
Ito, K., Kohata, Y., and Koyama, Y. (2011). Influence of additive amount of cement
solidification agent on mechanical characteristics of Liquefied Stabilized Soilmixed with fibered material, Japanese Geotechnical Society Hokkaido Branch
Technical Report Papers, Vol.51, pp.131-136 (in Japanese).
Duong, Q.H., Kohata, Y., Omura, S., and Ozaki, K. (2014). Strength and deformation
characteristics of liquefied stabilized soil reinforced by fiber material preparedat laboratory and field, Geosynthetics Engineering Journal, Vol.29, pp.33-40.

47

CHAPTER 4APPARATUS AND TESTING PROCEDURES

4.1 INTRODUCTION
In order to study the strength and deformation properties of the LSS, a series oftests at laboratory and field were performed. In this chapter, the apparatus and testingprocedures will be detailed.
4.2 APPARATUS AND TESTING PROCEDURE
4.2.1 Experiment at laboratory
4.2.1.1 Triaxial apparatus
A triaxial shear test is a common method to measure many deformable solids'
mechanical properties, especially soil (e.g., sand, clay) and rock, and other granularmaterials or powders. There are several variations on the test (Bardet J. P, 1997; Head K.
H et al., 1998; Holtz R. D et al., 1981; Price D. G et al., 2009).
In a triaxial shear test, stress is applied to a sample of the material being tested
in a way which results in stresses along one axis being different from the stresses inperpendicular directions. This is typically achieved by placing the sample between twoparallel platens, which apply stress in one (usually vertical) direction, and applying fluidpressure to the specimen to apply stress in the perpendicular directions. (Testing apparatus
which allows the application of different levels of stress in each of three orthogonal
directions are discussed below, under "True Triaxial test.")The application of different compressive stresses in the test apparatus causes
shear stress to develop in the sample; the loads can be increased, and deflections
monitored until failure of the sample. During the test, the surrounding fluid is pressurized,
and the stress on the platens is increased until the material in the cylinder fails and forms
sliding regions within itself, known as shear bands. The geometry of the shearing in a48

triaxial test typically causes the sample to become shorter while bulging out along thesides. The platen's stress is then reduced, and the water pressure pushes the sides back in,
causing the sample to grow taller again. This cycle is usually repeated several times whilecollecting stress and strain data about the sample. During the test, the pore pressures of
fluids or gasses in the sample may be measured using the pore pressure apparatus.
From the triaxial test data, it is possible to extract fundamental material
parameters about the sample, including its angle of shearing resistance, apparent cohesion,and dilatancy angle. These parameters are then used in computer models to predict how
the material will behave in a larger-scale engineering application. An example would be
to predict the soil's stability on a slope, whether the slope will collapse or whether the soil
will support the shear stresses of the slope and remain in place. Triaxial tests are usedalong with other tests to make such engineering predictions.
During the shearing, a granular material will typically have a net gain or loss ofvolume. If it had originally been in a dense state, then it typically gains volume, acharacteristic known as Reynolds' dilatancy. If it had originally been in a very loose state,then contraction may occur before the shearing begins or in conjunction with the shearing.
Sometimes, testing of cohesive samples is done with no confining pressure in an
unconfined compression test. This requires much simpler and less expensive apparatus
and sample preparation, though the applicability is limited to samples that the sides won't
crumble when exposed, and the confining stress being lower than the in-situ stress gives
results which may be overly conservative.
In this study, laboratory tests were carried out in triaxial undrained conditions.
The effective confining pressure was controlled to be around 98 kPa with a back pressureof 196 kPa and cell pressure of 294 kPa in all cases. The specimen's axial strain wasmeasured by a couple of Local Deformation Transducer (LDT) (Goto et al. 1991). The
LDT, which was set at the diagonally opposite ends of the specimen, is avoided the effectof bedding error caused by loose layers at the top and bottom end of the sample. The top
and bottom ends of LDT was pinched between two pseudo-hinged attachments fixed on
the surface of the rubber membrane at the points, which were glued to the specimen toprevent slipping between the membrane and the surface of the specimen. When the valueof LDT exceeds a measurable range, the axial displacement was used the value ofproximity transducer (Gap sensor) and dial gauge by correcting the bedding error. In thistest, a digital servo motor was used for the loading device. This motor enables to control
49the axial displacements with high precision and can ignore backlash when reversing theloading direction. A PC software automatically controlled the whole operation of theapparatus during a test. The drawing of the apparatus for triaxial compression tests wasshown in Figure 4.1.

Figure 4.1 The drawing of the apparatus for triaxial compression testso Direct drive motor:
Direct drive motor enables to control the axial displacements with high precisionand can ignore backlash when reversing the loading directiono Dial gauge:
Dial gauge (Figure 4.2) is applied to measure the global displacement ofspecimen during compression test. The pointer of the gauge is touched with a metal platefixed on the loading rod outside the cell.

50

Figure 4.2 Dial gaugeo Gap sensor ( Contactless displacement transducer):
The contactless displacement transducer (Figure 4.3) is applied as the
supplement of the dial gauge to measure the global displacement of the specimen. Thiskind of contactless displacement transducer has much more accuracy than the dial gauge
but the measuring range is limited from 0 to 2 mm generally.

Figure 4.3 Gap sensor
o Axial load cell:
The axial load cell can measure the axial loading applied to the specimen.
o Local displacement transducer (LDT)The axial strain was measured by a local displacement transducer (LDT) (Figure4.4) which removes the influence of bedding error and has a highly accurate measurement
at the shear strain level.
51

Figure 4.4 Setting LDT on the test sample
o Transducer for pore pressure and cell pressure:
Pore Pressure Transducer allows precision measurement of soil sample porewater pressure during triaxial and permeability testing. Cell Pressure transducer is used
for the measurement of pressure, backpressure in the triaxial cell. They have to beconnected to triaxial cells by the suitable De-airing block. The transducers are base on theextent metric measurement principle with strain gauges on the metal base (Figure 4.5).

Figure 4.5 Pore pressure and cell pressure transducer
524.2.1.2 Testing procedure
The triaxial compression test procedure will be performed as follows in Fig. 4.6.
• Preparation of test equipment

Step 1• Preparation of the specimen

Step 2• Setting of the specimen

Step 3• Double negative pressure method

Step 4• Back pressure

Step 5• Isotropic consolidation

Step 6• Loading

Step 7• After the completion of loading

Step 8Figure 4.6 The triaxial compression test procedure
4.2.2. Experiment at field
4.2.2.1 Falling Weight Deflectometer (FWD) test
The Falling Weight Deflectometer (FWD) is an instrument that makes the weight
fall freely on its loading plate to apply impact load and measures the displacement causedby the fall at the center of impact load and at the points in a radial direction from thecenter of impact load.
A kind of instrument that is mounted on or drawn by a vehicle used to constructconcrete pavement or asphalt pavement of a runway is usually called FWD. The impact
load of FWD is 49 kN to 196 kN, and it can obtain the modulus of elasticity of each53

pavement layer by back analysis based on the theory of multi-layer elasticity using 6 to 8
of external displacement sensors (Figure 4.7).

Figure 4.7 Falling Weight Deflectometer (FWD) apparatus
On the other hand, the small FWD is an FWD that is constructed small and easy
and is applicable for hand carry. It makes the weight fall freely on the loading plate toapply impact load and measures the load and displacement caused by the fall. It wasdeveloped mainly by assessing the rigidity and bearing capacity of the subgrade easily
and promptly. It can measure many points in the short term and obtain a coefficient ofsubgrade reaction and modulus of subgrade elasticity without using reaction facilities likea plate bearing test or CBR test. It was called Portable Falling Weight Deflectometer(PFWD) (Figure 4.8).

Figure 4.8 Portable Falling Weight Deflectometer (PFWD) apparatus54

In this study, to determine the stiffness of the LSS ground, PFWD equipment
was used. The basic structure of PFWD in Japan has a weight that can be lifted by hand,
and the total weight of equipment is less than 30 kg. Generally, the fall height of thefalling weight for the necessary impact load to occur is equal to or less than 0.7 m. The
rod guides for weight falling and slide seal is furnished to decrease friction. Also, a fixable
mechanism of weight falling is furnished to fix the weight stable at a specified height.
The half sine-wave profile of impact load through rubber buffer shows a gradual peak, ittakes 7 – 15 ms from the beginning of loading to the peak. The typical structure of PFWD
is shown in Figure 4.9.
In general, the stiffness of natural/artificial ground is evaluated by the plate load
test which calculates K30-value with a 30 cm diameter loading plate from the relation
between 1.25 mm displacement and corresponded load strength at static loading. In
portable FWD tests, loading and displacement are measured and obtains KP.FWD-value
from its relation. The value evaluates the stiffness of the ground. In this study, the loadingplate diameter of the apparatus was 10 cm which was different from that of the plate load
test. Therefore, the loading plate diameter was corrected, and the KP.FWD-value at 30 cm
loading plate diameter was calculated as the following equation by JSCE (2002).
KP.FWD = (PP.FWD.φ/δP.FWD.φ).(φP.FWD/δPLT) (MN/m3)
Where:
PP.FWD.φ: loading stress at displacement δP.FWD.φ
δP.FWD.φ: displacement
φP.FWD: loading plate diameter of portable FWD
φPLT: loading plate diameter of plate load test (30 cm)

55(4. 1)

Figure 4.9 The typical structure of PFWD
Therefore, the measurement was conducted to obtain at least three different
displacements including 0.417 mm (1.25 mm×φP.FWD/30 cm) in the middle, bychanging weight mass and falling height. One of the displacements would be near 0.417
mm as shown in Figure 4.10.

Figure 4.10 An example of displacement and loading stress at one measurement point
The number of falls at one measurement point was 5 times. The reason is themeasurement result at first fall varies due to unstable contact between the loading plate
and the ground. The first fall is regarded as the primary fall, so the load and displacement56

from the second fall are recorded as measurement data and averaged. This was repeatedthree times to obtain the relationship as shown in Figure 4.10. And then, the KP.FWD-value
was calculated using Equation 4.1. The model ground was subjected to the test at thedesigned curing time.
4.2.2.2 Testing procedure
The procedure of PFWD measurement is as follows in Figure 4.11.

Step 1• Remove the sand, soil materials on the surface of LSS
ground, and level it as possible.

Step 2• Place PFWD at the measurement point on the surface of
LSS ground.

Step 3• Free-fall the weight from the design height for the firsttime

Step 4• Free-fall the weight from the design height for thesecond time

• Record the data
Step 5• Repeat step 4 and step 5 three times
Step 6

Figure 4.11 The PFWD test procedure

57

REFERENCES
Bardet J. P., Experimental Soil Mechanics, Prentice Hall. ISBN 978-0-13-374935-9, 1997.
Head K. H., Effective Stress Tests, Volume 3, Manual of Soil Laboratory Testing, (2nded.). John Wiley & Sons. ISBN 978-0-471-97795-7, 1998.
Holtz R. D, Kovacs, W. D., An Introduction to Geotechnical Engineering. Prentice-Hall,
Inc, ISBN 0-13-484394-0, 1981.
Price D. G, De Freitas, M. H (ed.)., Engineering Geology: Principles and Practice,Springer, p. 450. ISBN 3-540-29249-7, 2009.
Goto, S., Tatsuoka, F., Shibuya, S., Kim, Y-S., and Sato, T. (1991). A simple gauge for
local small strain measurements in the laboratory, Soils, and Foundations, Vol.31,
No.1, pp.169-180.
Japanese Society of Civil Engineering ed. (2002): Operation manual of FWD and portable
FWD, Pavement engineering library 2, 72-73 (in Japanese).

58

CHAPTER 5
VARIOUS FACTORS ON THE STRENGTH AND DEFORMATIONPROPERTY OF LIQUEFIED STABILIZED SOIL PREPARED AT
FIELD

5.1 INTRODUCTION
Nowadays, the rapid urbanization and modernization in big cities in developing
countries such as Jakarta, Hanoi and Ho Chi Minh, etc., is the cause of the state ofinfrastructure, which does not meet the needs of society. Especially, serious congestionof the traffic is happening on a large scale caused by overpopulation. With limited urban
areas and solving the above problems, the construction of underground facilities likesubway, underground parking, and pedestrian tunnels is the most effective solution.
However, millions of cubic meters of excavated soil will arise to be trucked fromunderground construction projects to disposal sites. It is the cause of environmental
pollution.
Besides, sand from rivers and rocks from mountains are the main material usedas backfilling soil in the constructions. It is leading to increasingly depleted natural
resources and serious impacts on the natural environment. According to statistics by the
Ministry of Environment of Vietnam, the current demand for sand is about 600 million
m3 per year, the resources of sand will be exhausted and out of reserves about 10 years
later. On the other hand, the disposal sites are becoming increasingly scarce andoverloaded in the big cities. Therefore, the excavated soil is a serious problem in the big
cities in Vietnam. The questions are where to put the excavated soil and how to develop
sustainable infrastructure, which does not only reduce the cost of construction but also
does not affect the natural environment.
A long time ago in the big cities in Japan such as Tokyo, Kyoto, and Osaka, etc.,
when the subway lines, underground constructions, and high-rise buildings were built,
the Japanese government also faced this same situation in Vietnam. In order to solve the59above problem, one of the methods was recycling the excavated soil as backfilling soil.
It is mentioned by Kuno (1997) that "Liquefied Stabilized Soil" (LSS) is one of theeffective methods of using the excavated soil with construction works and has become
popular in Japan. The LSS is a kind of cement-treated soil, which is prepared by mixing
slurried soil and cement stabilizer. The LSS mixtures are not only created stabilized
ground without compaction but also easy to fill empty space by pumping a long distance.
However, according to previous studies, it is shown that the increase in cement content
does not only increase the strength property but also the brittleness increases. Therefore,
Kohata et al. were proposed the LSS mixed the pulverized newspaper as fiber material inorder to improve the brittle mechanical property and to increase the ductile performanceof LSS (Kohata et al., 2002). It was shown that the ductile property of LSS mixed withpulverized newspaper as a fiber material after the peak in the q~εa curve was significantly
improved by the reinforcement method (Kohata 2006; Kohata et al., 2004 and 2007; Itoet al., 2011). However, it has not been explained about the influences of various factors
on the strength and deformation property of LSS with fiber material prepared at the field(Duong et al., 2014).
In this study, two pits were excavated on the campus and then were filled with
LSS mixed with fiber material amount 0, 10 kg/m3, respectively. After a curing time of
28 and 56 days, the specimens were prepared by trimming LSS retrieved from the model
ground. A series of Consolidated-Undrained triaxial compression tests with pore watermeasurement was carried out on the specimens cured in the field ground under theconditions at a constant strain rate of 0.054 %/min and the effective confining pressure of
98 kPa. And also, the applicability of an evaluation of stiffness by portable FWD test ata backfilling ground by LSS mixed with fiber material was investigated. Based on the test
results, the influences of various factors, which are curing days, paper content, curing
temperature and curing circumstance, etc., on the strength and deformation property of
LSS prepared at the field are discussed.
5.2 TEST PROCEDURE
5.2.1 Test materials
In this study, a commercially available NSF-Clay in Japan was used in theexperiment. This clay is a homogeneous cohesive soil with the physical parameters shownin Table 5.1. The special cement, namely Geoset 200 of Taiheiyo Cement Co. was used60

as the cement stabilizer. The pulverized newspaper was used as the fiber material, which
was made by the following procedure. The newspaper was cut by the office shredder into
small pieces. The cut papers were mixed with water and pulverized by a food processor
for cooking. The paper was untied by the hand after dried in a drying oven. It was
pulverized again to smaller pieces like cotton by the food processor.
Table 5.1 Physical properties of NSF-Clay
Density of particle s (g/cm3)

2.762

Liquid limit WL (%)

60.15

Plastic Limit WP (%)

35.69

Plasticity Index IP

24.46

5.2.2 Mixing method
The slurry type and the adjustment slurry type are two LSS mixing methods,
which are the common mixing methods for recycling excavated soil. The slurry type waschosen for this study because it prepares easier than the adjustment slurry type. In thismethod, an appropriate amount of water was added and mixed with excavated soil, thenthe density of slurry was adjusted, after that the cement stabilizer was added and mixed.
In the previous research, a variety of mixing tests was conducted to adjust theslurry density and the amount of cement stabilizer. The bleeding rate, flow value, andunconfined compressive strength were investigated by soil tests corresponding to eachparameter for each of LSS at the curing time of 28 days (Ito et al. 2011; Duong et al.,2014). Based on these tests, the standard slurry density was decided for this study.
5.2.3 Specimen preparation
In this study, the target density of LSS was 1.280 g/cm3, the bleeding rate wasless than 1 % and the cement content was 80 kg/m3 according to the standard mix
promotion design by Ito et al. (2011). LSS slurry was made by the following procedure.
NSF-CLAY and water were put into a big bucket and mixed by hand mixer. The densityof the mixture was adjusted to 1.280 g/cm3 by measuring the mass of slurry filled into astainless steel container of 400 cm3 called "AE mortar container".
61

After that, the cement content of 80 kg/m3 was put into the mixture and mixed
slowly and carefully by hand mixer. The flow test was controlled according to the JHS
A313-Japan Highway Public Corporation Standard in order to measure the liquidity of
LSS. The fiber material amount of 0 and 10 kg/m3, respectively, were added with LSS
slurry and mixed slowly and carefully by hand mixer.
For making samples in the field, two pits were excavated at the test field on thecampus as shown in Figure 5.1. A nonwoven geotextile filter was set to prevent the
seepage of the mixture to the ground. The mixture of LSS and fiber material was filled
up two pits and the surface was covered with a polymer sheet and cured under nature
condition. The temperature was measured hourly by a temperature sensor installed in the
excavated hole in the field of the campus as shown in Figure 5.2. After a curing time of
28 and 56 days, respectively, the samples prepared by trimming LSS retrieved from thetest field were subjected to CUB tests, and the conditions of specimens on the CUB test
were shown in Figure 5.3. In parallel, the model ground was subjected to portable FWD
tests.

Figure 5.1 Schematic drawing of pits

62

Figure 5.2 Setting temperature sensor in the model ground5.2.4 Test method and equipment
5.2.4.1 CUB test
Figure 5.3 illustrates the drawing of the apparatus for triaxial compression tests.
The axial strain of the specimen was measured by a couple of Local Deformation
Transducer (LDT) (Goto et al., 1991). The LDT, which was set at the diagonally opposite
ends of the specimen, is avoided the effect of bedding error caused by loose layers at the
top and bottom end of the sample. The top and bottom ends of LDT was pinched between
two pseudo-hinged attachments fixed on the surface of the rubber membrane at the points,
which were glued to the specimen to prevent slipping between the membrane and thesurface of the specimen. When the value of LDT exceeds a measurable range, the axial
displacement was used the value of proximity transducer (Gap sensor) and dial gauge bycorrecting the bedding error. In this test, a digital servo motor was used for the loading
device. This motor enables to control the axial displacements with high precision and canignore backlash when reversing the loading direction. A PC software automaticallycontrolled the whole operation of the apparatus during a test.

63Figure 5.3 Schematic figure of the test apparatus
The LSS specimens (Pc-0, Pc-10) at curing time of 28 and 56 days were carriedout by CUB tests. The specimens were saturated by using the double vacuum pressure
method. The de-air water flowed through the specimen under the backpressure of 196
kPa. The isotropic consolidation was performed for 16 hours under the effective confiningpressure of 98 kPa. After that, the triaxial shear was carried out under the constant strain
rate, 0.054 % / min.
5.2.4.2 Portable Falling weight deflectometer (FWD) test
The schematic of a portable FWD test apparatus is shown in Figure 5.4. The
apparatus consists of the weight to fall freely on its loading plate to apply impact load andthe acceleration sensors to measure the displacement caused by the fall at the center ofimpact load and also at points in a radial direction from the center of impact load.

64

Figure 5.4 Schematic of portable FWD test apparatus
Generally, the stiffness of natural/artificial ground is evaluated by the plateloading test. From this test, the K30-value with a 30 cm diameter loading plate is obtained
from the relation between 1.25 mm displacement and corresponded load strength on static
loading. In portable FWD tests, loading and displacement are measured and KP.FWD-value
is obtained from its relation. The value evaluates the stiffness of the ground. In this study,
the loading plate diameter of the apparatus was 10 cm. Therefore, the KP.FWD-value at 30
cm loading plate diameter was calculated as the Eq. (5.1).
KP.FWD = (PP.FWD.φ/δP.FWD.φ).(φP.FWD/δPLT) (MN/m3)(5.1)

Where:
PP.FWD.φ: loading stress at displacement δP.FWD.φ
δP.FWD.φ: displacement
φP.FWD: loading plate diameter of portable FWD
φPLT: loading plate diameter of plate load test (30 cm)
The model ground was subjected to the test at a curing time of 28 and 56 days,
65

respectively.
5.3 TEST RESULT AND DISCUSSION
5.3.1 Relationship between deviator stress and axial strain
Figure 5.5 shows the change in the temperature of the environment during thecuring period, measured hourly by a temperature sensor installed at the excavation holein the field of the campus. It is seen that the average temperature is about 9oC from earlyNovember until about November 20. From November 20, the average temperature isabout 5oC. There is a decreasing trend in temperature during the curing time. It is
explained by the weather conditions of the Hokkaido area, which is changing fromautumn to winter.
Figure 5.6 shows the relationship between the curing temperature (averagetemperature in the ground) and the maximum deviator stress qmax. The maximum deviator
stress has been obtained from the relationship between deviator stress q ((=  andaxial strain a, which were results of CUB test under the confining pressure ’c = 98 kPaof LSS mixed with fiber material of 0, 10 kg/m3 (Pc-0, 10), respectively at 28 and 56
curing days. It is found that the qmax of paper content 0 kg/m3 (Pc-0) in case of reducing
the temperature in the ground from 9.1oC to 7.3oC trends to be almost constant. On theother hand, the qmax of Pc-10, which is the LSS mixed with fiber material of paper content
10 kg/m3, increases as the decrease of the temperature in the ground from 9.1oC to 6.2oC.
It is considered that this is due to the increase of the curing days.
12
11

Temperture(℃）

10
9
8
7
6
5
4
10/30

11/9

11/19

11/29

12/9

12/19

12/29

Curing date

Figure 5.5 Relationship between temperature and curing date
66

250

Pc-0 28 days
Pc-0 56 days
Pc-10 28 days
Pc-10 56 days

225

qmax

200

175

150

125

100
5

6

7

8

9

10

Temperture(℃)

Figure 5.6 Relationship between qmax and temperature
The relationship between the deviator stress q and the axial strain a is shown in
Figure 5.7. It can be seen that the deviator stresses of Pc-0 are larger than Pc-10, but theq~εa curve of Pc-0 after the peak decreases suddenly. And more, the deviator stress of Pc0 at 28 curing days tends slightly larger than that one at 56 curing days. It can beconsidered due to curing conditions where the temperature and humidity at field are notconstant and very different from indoor curing conditions. Or maybe the strength of thesample was influenced by the sampling disturbance. To make this point more clear, weneed to conduct more field tests the next time.
250

Deviator Stress,q (kPa)

200

150

100

Pc-0-28 days
Pc-0-56 days
Pc-10-28 days
Pc-10-56 days

50

0
0.0

0.5

1.0

1.5

2.0

2.5

Axial Strain,εa (%)

Figure 5.7 Relationship between deviator stress q and axial strain εa67

However, in the case of Pc-10, an increasing trend of the deviator stress is seenas the curing days increase and the deviator stress after the peak does not reducesignificantly for both 28, 56 curing days, respectively. It is considered that there is areinforcement effect by adding fiber material into LSS.
Therefore, from the above results, it is seen that curing temperature could affectthe deviator stress of LSS without fiber material. As for LSS with fiber material, there isan independence of the deviator stress q on the curing temperature when the curing days
increases. The brittle property of LSS without fiber material has been improved by thereinforcement effect of adding fiber material as similar to the previous researches (Kohata
et al., 2007; Ito et al., 2011; Duong et al., 2104). It is found that aseismic performance inthe ground is improved and toughness ground will be constructed when the LSS withfiber material is used as backfilling.
5.3.2 Deformation property
5.3.2.1 Definition of Young’s modulus

Figure 5.8 Definition of various Young’s moduli
The definitions of various Young’s moduli are indicated in Figure 5.8. The initial
Young’s modulus E0 is defined as initial stiffness at a small strain of εa = 0.002 % or less.
The tangent Young’s modulus Etan is defined as a tangential gradient in the q~εa curve,
and it indicates the non-linearity of deformation property in q~εa relation. The equivalent
Young’s modulus Eeq is obtained from a small unloading/reloading loop during
68monotonic loading. Moreover, the Eeq in creep correction is calculated from the slope ofthe lower limit point and the midpoint in a line connecting the unloading point and theintersection of the q~εa curve in reloading. The Eeq indicates a changing of damage degree
during shear (Kohata et al., 1997 and 1999).
5.3.2.2 Initial Young’s modulus E0
Figure 5.9 shows the influence of curing temperature on Initial Young’s modulus
E0 of Pc-0, 10 respectively at 28 and 56 curing days. It is found from Figure 5.9 that E0
values of Pc-0 at 28 and 56 curing days have almost no change. It is seen that the effectof curing temperature on E0 values of Pc-0 is small. Moreover, the E0 value of Pc-10 at
56 curing days is larger than E0 value of 28 curing days. Therefore, it is considered thatthe effect of curing temperature is smaller than that of curing days on Initial Young’s
modulus E0.

700
650
600

E0

550
500
450
400
350
300
5.0

Pc-0 28 days
Pc-0 56 days
Pc-10 28 days
Pc-10 56 days
5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

Temperture(℃)

Figure 5.9 Relationship between E0 and temperature
5.3.2.3 Tangent Young’s modulus Etan
The relationship between Etan/E0 and q/qmax of Pc-0, 10, respectively, at 28 and
56 days is shown in Figure 5.10. The values were obtained from the q~εa curve of the
CUB test under the confining pressure of 98 kPa. In this Figure, the reduction rate of
Etan/E0 shows a similar tendency in both Pc-0 and Pc-10 at 28 and 56 days, respectively.
However, the reduction rate of Etan/E0 of Pc-0 is larger than Pc-10 at both 28 and 56 days.
69

Therefore, it is considered that the effect of adding the fiber material on LSS increases
the non-linearity of deformation property in q~εa relation while the curing temperature islower.
1.0

Pc-0 28 days
Pc-0 56 days
Pc-10 28 days
Pc-10 56 days

0.8

Etan/E0

0.6

0.4

0.2

0.0
0.0

0.2

0.4

0.6

0.8

1.0

q/qmaxFigure 5.10 Etan/E0 ~ q/qmax relations
5.3.2.4 Equivalent Young’s modulus, Eeq
Figure 5.11 shows the relationship between Eeq/E0 and q/qmax of Pc-0, 10,
respectively, at 28 and 56 days. The Eeq values are obtained from the q~εa curve of CUB
tests under confining pressure 98 kPa at a small loading/reloading loop during monotonic
loading. According to the previous study, Initial Young's modulus of cement-treated soil
at a small strain was independent of the confining pressure. Therefore, the Eeq/E0 is
considered to express the degree of damage during shear. At the first period of the curing
process, the soil sample is locally broken, and the collapse of soil progresses as the load
value increases during shear. Finally, the specimen failures wholly as the shear band
formed by the accumulation of local damages. This is explained that the cementation or
microstructure between particles of soil is damaged. It caused the changes in the elasticity
property of soil.
It is seen from Figure 5.11 that the reduction rate of Eeq / E0 of Pc-0 is larger than
Pc-10 at 28 days. For the sample of 56 days, there is no significant difference between
the reduction rate of Eeq / E0 of both Pc-0 and Pc-10. It is considered that during the first
period of the curing process of LSS mixed fiber material, the addition of the fiber material
into LSS is reduced the damage degree during shear. However, there is unclear when the70curing days increases and the curing temperature drops significantly. It is probably due
to the effect of the freezing and thawing process of water inside the sample under the fieldor the disturbance at the time of sampling (Duong et al., 2014). For this result, it
considered conducting further works the next time.
1.0

Eeq/E00.8

0.6

Pc-0 28 days
Pc-0 56 days
Pc-10 28 days
Pc-10 56 days

0.4

0.2
0.0

0.2

0.4

0.6

0.8

1.0

q/qmaxFigure 5.11 Eeq/E0 ~ q/qmax relations
5.3.3 Strain level – dependency of Young’s modulus

700

Pc-0 28day
Pc-0 56day
EP.FWD 28day
EP.FWD 56day

600
500

Tangent Young's modulus,Etan(MPa)

Tangent Young's modulus,Etan(MPa)

700

400

Pc-0
300
200
100
0

(a)

1E-4

1E-3

0.01

0.1

1

Pc-10 28day
Pc-10 56day
EP.FWD 28day
EP.FWD 56day

600
500
400

Pc-10
300
200
100

(b)

0
1E-4

1E-3

0.01

0.1

1

Axial Strain,εa(%)

Axial Strain,εa(%)

Figure 5.12 EP.FWD and Etan ~ log εa relations
Figure 5.12 (a) and (b) show the strain level-dependency of tangent Young's
modulus Etan obtained in q~εa relation from CUB tests of Pc-0 and Pc-10 at 28 and 56
days, respectively. And also, the value of EP.FWD in each sample is shown in this figure.
71

The EP.FWD value was calculated from the value of KP.FWD, which was obtained by aportable FWD test performed on the surface of field ground. As shown in this figure, thevalues of Etan and EP.FWD at the same strain level are approximately equal. It is found that
the K-value by portable FWD can be evaluated the stiffness of backfilling ground by LSS
with fibered material adequately.
5.4 SUMMARY
To investigate the effect of various factors on the strength and deformation
property of Liquefied Stabilized Soil prepared at field, the specimens prepared bytrimming LSS retrieved from the model ground (field LSS) by block sampling were
subjected to CUB tests. In parallel, the portable FWD tests were carried out on the
backfilling ground at a curing time of 28 and 56 days.
The following conclusions were derived based on test results.
o The curing temperature could affect the deviator stress q of LSS without fiber material.
As for LSS with fiber material, there is an independence of the deviator stress q on
the curing temperature when curing days increases. The brittle property of LSS
without fiber material has been improved by the reinforcement effect of adding fiber
material. It is found that aseismic performance in the ground is improved andtoughness ground will be constructed when the LSS with fiber material is using as
backfilling.
o The effect of curing temperature is smaller than that of curing days on

InitialYoung’s modulus E0.
o The effect of adding the fiber material on LSS increases the non-linearity of
deformation property in q~εa relation while the curing temperature has been lower.
o During the first period of the curing process of LSS mixed fiber material, the additionof the fiber material into LSS is reduced the damage degree during shear. However,there is unclear when the number of curing days increases and the curing temperaturedrops significantly. For this result, it considered conducting further works the nexttime.
o The K-value by portable FWD can be evaluated the stiffness of backfilling ground by
LSS with fibered material adequately.

72

REFERENCES
Duong, Q.H., Kohata, Y., Omura, S., and Ozaki, K. (2014). Strength and deformation
characteristics of liquefied stabilized soil reinforced by fiber material preparedat laboratory and field, Geosynthetics Engineering Journal, Vol.29, pp.33-40.
Goto, S., Tatsuoka, F., Shibuya, S., Kim, Y-S., and Sato, T. (1991). A simple gauge for
local small strain measurements in the laboratory, Soils, and Foundations, Vol.31,
No.1, pp.169-180.
Ito, K., Kohata, Y., and Koyama, Y. (2011). Influence of additive amount of cement
solidification agent on mechanical characteristics of Liquefied Stabilized Soilmixed with fibered material, Japanese Geotechnical Society Hokkaido Branch
Technical Report Papers, Vol.51, pp.131-136 (in Japanese).
Kohata, Y. (2006). Mechanical property of liquefied stabilized soil and future issues,
Doboku Gakkai Ronbunshuu, F, Vol.62, No.4, pp.618-627 (in Japanese).
Kohata, Y., Fujikawa, T., Ichihara, D., Kanda, M., and Murata, O. (2002). Strength anddeformation properties of fibered material mixed in liquefied stabilized soil
obtained from uniaxial compression test, Proc. of the 36th Japan National Conf.
on Geotech. Eng., pp.635-636 (in Japanese).
Kohata, Y., and Tsushima, H. (2004). Effect of fibered material mixing in liquefied
stabilized soil on the triaxial shear characteristics, Proc. of the 39th Japan
National Conf. on Geotech. Eng., pp.721-722 (in Japanese).
Kohata, Y., Ichikawa, M., Nguyen, C. Giang., and Kato, Y. (2007). Study of damage
characteristics of liquefied stabilized soil mixed with fibered material due totriaxial shearing, Geosynthetics Engineering Journal, Vol.22, pp.55-62 (inJapanese).
Kohata, Y., Tatsuoka, F., Wang, L., Jiang, L. G., Hoque, E., and Kodaka, T. (1997).
Modeling the non-linear deformation properties of stiff geomaterials,
Geotechnique, Vol.47, No.3, pp.563-580.
Kohata, Y., Jiang, L. G., Murata, O., and Tatsuoka, F. (1999). Elastic-properties-basedmodeling of non-linear deformation characteristics of gravels, Proc. of the73second Inter. Symposium on Pre-Failure Deformation Characteristics ofGeomaterials-IS Torino 99, pp.533-539.
Kuno, G., eds (1997). Liquefied stabilized soil method-Recycling technology ofconstruction-generated soil and mud, Gihodo publication (in Japanese).

74

CHAPTER 6
EVALUATION OF THE REDUCTION OF THE SEISMIC
MOTION TO GROUND SUBJECTED BY USING LIQUEFIEDSTABILIZED SOIL

6.1 INTRODUCTION
A long time ago, in the big cities in Japan such as Tokyo, Nagoya, and Osaka,
etc., when the subway lines, underground constructions, and high-rise buildings werebuilt, millions of cubic meters of soil were excavated. The soil was carried by trucks fromunderground construction sites to disposal sites, which was the cause of environmental
pollution. With limited urban land, landfill sites were more and more scarce and led to an
overload state. The questions were where to put the excavated soil and how to develop
sustainable infrastructure, which did not only reduce the cost of construction but also did
not affect the natural environment. To solve these problems, one of the methods wasrecycling the excavated soil as backfilling soil. "Liquefied Stabilized Soil" (LSS), which
was reported by Kuno (1997), is one of the effective methods of using the excavated soil
with construction works and has become popular in Japan. The LSS is a kind of cementtreated soil, which is prepared by mixing slurried soil and cement stabilizer. The LSS
mixtures are not only created stabilized ground without compaction but also easy to fillspace by pumping a long distance. However, the increase in cement content does not only
increase the strength property, but also the brittleness increases. To improve the ductile
performance of LSS, a reinforcement method has been created by mixing the newspaper
as a fiber material into LSS. It was shown that the ductile property of LSS mixed withpulverized newspaper as a fiber material after the peak in the q ~ εa curve was significantly
improved by the reinforcement method (Kohata et al., 2002, 2004, 2006 and 2007; Duonget al., 2014). There are many previous studies on the influence of various factors on LSS(Duong et al., 2015; Do et al., 2018 and 2019; Pham et al., 2019; Cui et al., 2020).
However, there is no research on the effect of using LSS as a backfilling material on the
structure and the ground when the earthquake occurs.
75

In this study, the effect of backfilling material on the building and the groundunder the earthquake is analyzed by using the FEM method. Based on the analysis results,
the influences of LSS as backfilling material on the building and the ground were discussed.
6.2 NUMERICAL SIMULATION
6.2.1 Simulation of study cases
In this study, it was assumed that a 10-story building with a basement wasconstructed by the open-pit method. The pit was excavated to the bottom of the basementwith the size as shown in Figure 6.1. When the basement is completed, the excavation
region will be filled with backfilling material. The backfilling content in each case would
be Case 1: backfilling soil (sandy soil), Case 2: LSS, and Case 3 was LSS mixed withfiber material (10 kg/m3). Subsequently, nonlinear time-domain dynamic analysis underthe earthquake was conducted. From the results, the effect of backfilling material on thebuilding under in each case was discussed. Acceleration and velocity of five points on the
ground surface A, B, C, D, E with distances of 0, 3, 5.95, 10.5, 18 m, respectively fromthe edge of the building were compared and investigated.
6.2.2 Numerical modeling and parameter
6.2.2.1 Structural modelingIn this study, a reinforced concrete ten-floor building frame, 30 m high and 12
m wide with 16 columns consisting of three spans of 4 m in each direction, and ten slabs
and one basement was selected, as shown in Figure 6.1. The height of the floors was 3 m,
and the basement floor was located at a depth of 4.5 m below the ground surface. The
reinforced concrete foundation was 15x15 m square, and 1 m thick, and the reinforced
concrete pile of 20 m depth and 1.2 m in diameter was selected to analyze in this study.
The structural sections were specified after conducting a routine design procedure
regulated in the relevant building codes (British standard, 2004). SAP2000 v 22 software
was utilized for the structural analysis and design of the cross-sections of columns andslabs. The parameters of the columns, floor, foundation, and pile are shown in Tables 6.1
and 6.2, respectively.

76

Figure 6.1 Dimension of the structure and excavation

Table 6.1 Characteristic of designed reinforced concrete column sections adopted in 3D FEM
Section TypeIx (m4)Iy (m4)

Area (m2)

E (kN/m2)

Type I (levels 1-5 and3.64E-3

7.45E-3

0.25

2.86E7



1.50E-3

3.05E-3

0.16

2.86E70.2

basement)
Type II (levels 6-10)

77

Table 6.2 Characteristic of designed reinforced concrete floor slabs and foundations
adopted in a 3D numerical model
Properties

Denote

Unit

Value

Floor slab thickness

hs

m

0.25

Basement wall thickness

hw

m

0.35

Foundation thickness

hf

m

1

Density



kN/m3

23.54

Young’s modulus

E

kN/m2

2.86E7

Poisson's ratio



-

0.2

The structural elements were modeled by using an elastic-viscoelastic
constitutive equation. In the time domain, material damping needs to be converted toRayleigh damping as follows (Ryan et al., 2008).
[C] = α [M] + β [K](6.1)

Where:[C]: damping matrix[M]: mass matrix[K]: stiffness matrix
α: mass-proportional coefficient
β: stiffness-proportional coefficient
The mass-proportional (α) and stiffness-proportional (β) coefficients arecalculated from selected natural frequencies and the damping ratio. The values of α andβ are defined as follows (Chopra, 2011):𝟐𝝎 𝝎

𝜶 = 𝝃 𝝎 𝒎+𝝎𝒏
𝒎

(6.2)

𝒏

𝟐

𝜷 = 𝝃 𝝎 +𝝎
𝒎

(6.3)

𝒏

Where:
𝝃: damping ratioωm = 2fm: angular frequency of corresponding mode m78ωn = 2fn: angular frequency of corresponding mode n
In this study, the natural frequencies of the building for the fixed base structure
were simulated by SAP 2000 v22 program as shown in Figure 6.2. Base on this simulation,
the first and second natural frequencies are selected to determine the values of ω1 = 7.96
(rad/s) and ω2 = 22.32 (rad/s), respectively. From Equation (6.2) and (6.3) with thematerial damping of 5 %, the mass-proportional and stiffness-proportional coefficientswere obtained as α = 0.5868 and β= 0.0033, respectively.

Mode 1: f1 = 1.267 Hz Mode 2: f2 = 3.553 Hz

Mode 3: f3 = 6.267 Hz

Mode 4: f4 = 8.968 Hz

Figure 6.2 The natural frequencies of the structure
6.2.2.2 Soil modeling and characteristic of backfilling materials
The present building is constructed on 30 m deep soft clayey soil on the bedrock.
From the previous research (Rayhani et al., 2008), this bedrock depth is reasonablebecause most of the amplification is in the first 30 m of the soil column. The propertiesof this soft soil were determined from actual in-situ and laboratory tests (Rahvar, 2006)
with a density of 14.416 kN/m3, a shear wave velocity of 150 m/s, and undrained shear
strength of 50 kN/m2. It was assumed that the groundwater level was equal to the level ofthe bedrock.
In this study, the properties of LSS and LSS with fiber (10 kg/m3) were achieved
from the laboratory tests. The relationship between deviator stress and axial strain of all79

samples Pc-0 (0 kg fiber/m3) and Pc-10 (10 kg fiber/m3) was shown in Figure 6.3. Becauseof the scattering of the laboratory experiments for a long time, the average parameters of
LSS and LSS with fiber were used in this simulation. LSS slurry was made by thefollowing procedure. New Snow Fine Clay (NSF-Clay) and water were put into a big
bucket and mixed by hand mixer. The density of the mixture was adjusted to 12.562
kN/m3 by measuring the mass of slurry filled into a stainless steel container of 400 cm3
called "AE mortar container". After that, the cement content of 80 kg/m3 was put into
the mixture and mixed slowly and carefully by hand mixer. The flow test was controlledaccording to the JHS A313-Japan Highway Public Corporation Standard to measure theliquidity of LSS. The fiber material amount of 10 kg/m3 were added with LSS slurry andmixed slowly and carefully by hand mixer. The damping ratio of LSS and LSS with fiber
is assumed as 10 and 12 % (Duong et al., 2015; Do et al., 2019).

Figure 6.3 The relationship between deviator stress and axial strain of LSS and LSS
with fiber.
On the other hand, characteristics of backfilling soil are considered as follows.
Because of not much investigation results on the stiffness of the backfilling soil, theinvestigation results on backfilling soil in Daikai station, which suffered from theSouthern Hyogo prefecture earthquake in 1995, were used as the backfilling soil
parameters. N value and unit weight, ρ was set at 10 and 17.0 kN/m3, respectively. Shear
modulus, G = 51.531 MN/m2, was estimated from N value by Railway Design Standard(1999). The damping ratio of backfilling soil was assumed as 4 %. The physical propertiesof backfilling materials are shown in Table 6.3.
80

Table 6.3 Parameters of backfilling materials
Material

E (kN/m2)

(kN/m3)

Vs (m/s)𝝃 (%)ν

Backfilling soil

1.529E5

17

150

4

0.49

LSS

2.942E5

13.356

269

10

0.49

LSS with fiber

3.567E5

14.69

282.6612

0.49

The Rayleigh damping coefficients of the soil are obtained from Equation (6.2)
and (6.3). The first and second natural frequencies of the soil are selected to calculate themass-proportional and stiffness-proportional coefficients. The values of natural
frequencies of the ground are calculated as the following equation (Kramer, 1996):
𝑉

𝑓𝑛 = 4𝐻𝑠 (2𝑛 − 1)

(6.4)

Where:
n: mode number
fn: natural frequency of the corresponding mode n
Vs: shear wave velocity of the soil deposit
H: soil deposit thickness
For multi-layer ground, the average shear wave velocity Vs,30 should becomputed by the following equation (Bristish standard, Eurocode 8, 1998-2004):
𝑉𝑠,30 =

30

(6.5)

ℎ𝑖
∑𝑁
𝑖=1𝑉
𝑖

Where:
hi: denote the thickness
Vs,30: average shear wave velocity (at a shear strain level of 10-5 or less) of the i-th
formation or layer, in a total of N, existing in the top 30 m.
The Rayleigh damping coefficients of the soil are shown in Table 6.4.

81

Table 6.4 Rayleigh damping coefficients of the soil
Case

Materialh(m) Vs(m/s) Vs,30(m/s)

f1

f2

1.28

3.84





0.48250.00250.60310.0031

1.282

0.00585

Backfilling
5.5

Case

172

soil

153.6

1
Soft clay soil

24.5

150

LSS

5.5

269

Case

163.24

1.36

4.08

2

Soft clay soil

24.5

150

0.641

0.00292

Case

LSS with

5.5

282.66

1.547

0.007

3

fiber

0.64450.0029

Soft clay soil

164.12
24.5

1.367

4.1

150

6.2.2.3 Seismic motion
In this study, the 1968 Tokachi-Oki earthquake in Hachinohe (Japan) was
selected and utilized onto the finite element numerical model for conducting a timehistory analysis. This earthquake has been chosen by the International Association for
Structural Control and Monitoring for benchmark seismic studies (Karamodin et al.,2010). The characteristics of the earthquake ground motions were indicated in Table 6.5,
and the time histories of the earthquake were shown in Figure 6.4. It was assumed thatthe earthquake ground motions are bedrock records.
Table 6.5 Characteristics of the adopted earthquake records
Earthquake

Country YearPGA (g)Mw (R)

Duration (s)Hypocentral
distance (km)Tokachi-Oki

Japan

1968

0.229

7.5

36

Note: PGA: peak ground acceleration; Mw: moment magnitude scale

82

14.1

2.5

Acceleration (m/s2)

2.0

Tokachi - Oki Earthquake (1968)
Mw= 7.2 (R), PGA = 0.229 (g)

1.5
1.0
0.5
0.0
-0.5
-1.0
-1.5

0

4

8

12

16

20

24

28

32

36

Time (s)Figure 6.4 The time histories of the 1968 Tokachi-Oki earthquake in Hachinohe cityin Japan
6.2.2.4 Numerical modeling in the ABAQUS program
In this study, the effect of backfilling material on the building and the groundunder the earthquake is analyzed by using ABAQUS 2020, a FEM analysis program. Bothlinear and nonlinear analyses are provided in ABAQUS to evaluate the interaction
between the building and the ground.
Beam elements (B33: 2 - node linear beam element in space) in ABAQUS areused for simulation of the columns. The floor slabs and basement walls were simulatedby the shell elements (S4R: 4-node, quadrilateral, stress/displacement shell element with
reduced integration), whereas the foundation and pile elements were modeled by solid
elements (C3D6: 3D, 6-node linear triangular prism elements). Besides, the soil medium
was modeled by using C3D8R elements (3D, 8- node linear brick, reduced integration,
hourglass control elements), and C3D6 elements. The free-field soil columns were
simulated by CIN3D8 elements with 3D, 8- node linear one-way infinite brick, but they
have defined orientations, unlike the other numerical elements. A summary of all element
types used in the FEM in this study is presented in Figure 6.5. The mesh of the structureand soil medium is shown in Figure 6.6 consists of 80135 elements and 109805 nodes.
Because this model is huge (approximately 98.2 gigabytes for a single case), the very fastcomputer at the Muroran Institute of Technology, Hokkaido, Japan, was used to conduct
this time history analysis, and even then, it took approximately 3 days (72 hours) to run a83single case under the applied earthquake motion. The results of the 3D finite-element
numerical simulation are discussed in the following sections.

Fig. 6.5 Element types used in FEM: (a) 2-node linear beam element in space (B33); (b)4-node, quadrilateral, stress/displacement shell element with reduced integration (S4R);(c) 3D, 6-node linear triangular prism elements (C3D6); (d) 3D, 8-node linear brick,
reduced integration, hourglass control (C3D8R); (e) 3D, 8-node linear one-way infinite
brick (CIN3D8)84

10 Floor slabs: 12 x 12 x 0.25 (m)4.5 (m)Type I: Levels 1-5 and basement
Column: 0.5 x 0.5 (m)Basement wall thickness: 0.35 (m)Length of pile = 20 (m)Basement

10 stories x 3 (m) = 30 (m)Type II: Levels 6-10
Column: 0.4 x 0.4 (m)Foundation: 15 x 15 x 1 (m)16 pilesDiameter: 1.2 (m). Length: 20(m)CIN3D8element

B33 element

C3D8R
element

S4R element
C3D6 element
CIN3D8element

Basement wall
element S4R

Foundation
element C3D6

Figure 6.6 The FEM of the structure and ground in the ABAQUS software program85

6.3 RESULT AND DISCUSSION
6.3.1 Maximum lateral displacement and inter-story drift
The maximum lateral displacement of the 10-story structure supported by thepile foundation under the 1968 Tokachi-Oki earthquake in each case is shown in Figure
6.7. It is found that the maximum lateral displacements of the building in Case 2 (LSS)
and Case 3 (LSS mixed with fiber) have a significant reduction trend when comparedwith Case 1 (Backfilling soil). It is explained that this is due to the stiffnesses of LSS andLSS mixed with fiber are much larger than backfilling soil. Besides, the maximum
displacement in Case 3 was a little smaller than in Case 2. It is considered that the effectof adding fiber material on LSS leads to increased stiffness and improved brittleness of
LSS.
10
9
8
Storey number

7
6
5
4
3
Case 1 (Backfilling soil)
Case 2 (LSS)
Case 3 (LSS with fiber)

2
1
0
0.36

0.37

0.38

0.39

0.40

0.41

Maximum Lateral Displacement (m)Figure 6.7 Maximum lateral displacement of the 10-story structure supported by pilefoundation under the 1968 Tokachi- Oki earthquake
The maximum inter-story drifts of the building were calculated by the following
equation (Standard Australia, 2007), and the results were indicated in Figure 6.8:
Drift =

di+1− di(6.6)

hWhere:
86

di+1: the deflection at the (i+1) level
di: the deflection at the (i) level
h: height of the story
Figure 6.8 shows that the inter-story drift of the building in Case 1 is the largest,
followed by Case 2, and Case 3 is the smallest. It was found that when using LSS as a
backfill material, the inter-story drift of the structure was reduced comparing to thebackfilling soil. In particular, this figure also clearly shows the effect of fiber material,
when mixed with LSS, will slightly reduce inter-story drift comparing with the case LSS
without fiber.
1098Storey Number

7
6

Case 1 (Backfilling soil)
Case 2 (LSS)
Case 3 (LSS with fiber)

5
4
3
2
1
0
0.00

0.05

0.10

0.15

0.20

0.25

Inter-story Drift (%)

Figure 6.8 The inter-story drift of the 10-story structure supported by pile foundation
under the 1968 Tokachi – Oki earthquake
Therefore, from the above results, it is seen that using LSS and LSS mixed withfiber as a backfilling material will reduce the lateral displacement and inter-story drift ofbuilding under the earthquake. Moreover, in this study, LSS mixed with fiber has a little
useful than LSS without fiber.
6.3.2 Relationship between acceleration and velocity with distance
The maximum acceleration and velocity of 5 points A, B, C, D, and E in boththe horizontal and vertical directions on the ground when affected by the earthquake are87shown in Figure 6.9 – 6.12, respectively.
From the four figures above, we can see that the maximum acceleration andvelocity values at 5 points in Case 2 is a little larger than in Case 3. Besides, there is ahuge difference between Case 1 with Case 2 and Case 3. There is a significant decrease
trend in maximum acceleration and velocity when using LSS with fiber as a backfillingmaterial compared with backfilling soil. Point A is the adjacent location to theconstruction, has the accelerating and speed with the highest reduction rate of 32.3 %,49.3 %, 3.2 %, and 24.8 %, respectively. It is followed by points B, C, and D that have adecreasing rate of acceleration and velocity inversely proportional to distance. In
particular, from Figure 6.10 and Figure 6.12, we can see that acceleration and velocity inthe vertical direction at point B has a reduction ratio slightly lower than point C. It is
explained that point C is a special point, where the junction between the two types of soil
is LSS and soft clayey soil. Finally, the location has the 18 meters farthest distance fromthe building is point E with almost no significant difference in the value of accelerationand velocity in the cases of LSS, LSS with fiber, and backfilling soil. It indicates thatwhen using LSS with fiber and LSS as a backfill material will significantly reduce theacceleration and velocity of the ground around the building and the surrounding area
when affected by the earthquake. It is considered by the fact that LSS with fiber and LSS
have much higher stiffness and damping than backfilling soil.

2

Maximum Horizontal Acceleration (m/s )

5.2
A

5.0

Case 1(Backfilling soil)
Case 2 (LSS)
Case 3 (LSS with fiber)

4.8
4.6
4.4
B
4.2

32.3%

4.0
C
3.8
3.6
3.4

19.9%

A

13.8%

B
A
0

C

4.8% D

C

D

B

3.2
2

4

D

6

8

10

E
E
3% E

12

14

16

18

Distance (m)Figure 6.9 Maximum horizontal acceleration at points A, B, C, D, and E

88

2

Maximum Vertical Acceleration (m/s )C

7

Case 1(Backfilling soil)
Case 2 (LSS)
Case 3 (LSS with fiber)

6
38.3%

A

5

D
C

B
4

D

D

B

3 A
2

C

35%

49.3%

15.2%

B

A

E
E
E

2.9%

0

2

4

6

8

10

12

14

16

18

Distance (m)Figure 6.10 Maximum vertical acceleration at points A, B, C, D, and E

0.360

B

Maximum Horizontal Velocity (m/s)

ACase 1(Backfilling soil)
Case 2 (LSS)
Case 3 (LSS with fiber)

0.355
3.2%

B
0.345

C

2.8%

0.350 AA

C 2.1%

D

B

1%

C

0.340

D

D
0.335

E
0.330
0.6%

E

E

0.325

0

2

4

6

8

10

12

14

16

18

Distance (m)Figure 6.11 Maximum horizontal velocity at points A, B, C, D, and E

89

Maximum Vertical Velocity (m/s)

0.12

C

A

0.11
0.10

D

21.9%

5.3%

C

24.8%

D

D
A

0.09

C
B

A
0.08

19.1%

0.07

B

0.06
0

2

B
4

E

Case 1(Backfilling soil)
Case 2 (LSS)
Case 3 (LSS with fiber)
6

8

10

12

14

E
E
1.6%

16

18

Distance (m)Figure 6.12 Maximum vertical velocity at points A, B, C, D, and E
Therefore, base on the above results, it is shown that the application of LSS withfiber as a backfill material will significantly reduce the acceleration and velocity of theground around the building and adjacent areas. Furthermore, the effect of adding fiber in
LSS was made more clear in this study. LSS mixed with fiber has more advantageousthan LSS without fiber.
6.4 SUMMARY
To investigate the effect of using LSS as a backfilling material on the building
and surrounding ground under an earthquake, the FEM of the structure and ground wassimulated by the ABAQUS software program. After that, a nonlinear time-domain
dynamic analysis under the earthquake was conducted. The displacement and inter-story
drift of the building and acceleration and velocity of the ground corresponding to eachkind of backfilling material were compared. Based on the analysis results, the following
conclusions were obtained.
o Using LSS with fiber and LSS as a backfilling material will slightly reduce the lateraldisplacement and inter-story drift of the building under the impact of the earthquake.
o The application of LSS with fiber and LSS as a backfill material will significantly
decrease the acceleration and velocity of the ground around the building and adjacentareas.
90

o The effect of fiber material, when mixed with LSS, was made clear in this study. LSS
mixed with fiber has more advantageous than LSS.
o It is considered that the LSS and LSS with fiber have an effective potential to reduce
the seismic motion on the buildings and the surrounding soil environment. This
property is a new advantage of LSS and LSS with fiber.

91

REFERENCES
Kuno G., Liquefied stabilized soil method- Recycling technology of constructiongenerated soil and mud, Gihodo publication, 1997 (in Japanese).
Kohata Y, Fujikawa T, Ichihara D, Kanda M and Murata, O., Strength and deformation
properties of fibered material mixed in liquefied stabilized soil obtained fromuniaxial compression test, Proc. of the 36th Japan National Conference on
Geotechnical Engineering, 2002, pp.635-636 (in Japanese).
Kohata Y and Tsushima H., Effect of fibered material mixing in liquefied stabilized soilon the triaxial shear characteristics, Proc. of the 39th Japan National Conference
on Geotechnical Engineering, 2004, pp.721-722 (in Japanese).
Kohata Y., The mechanical property of liquefied stabilized soil and future issues, Doboku
Gakkai Ronbunshuu, F, 2006, Vol.62, No.4, pp.618-627 (in Japanese).
Kohata Y, Ichikawa M, Nguyen C. G, and Kato Y., Study of damage characteristics ofliquefied stabilized soil mixed with fibered material due to triaxial shearing,
Geosynthetics Engineering Journal, 2007, Vol.22, pp.55-62 (in Japanese).
Duong H. Q, Kohata Y, Omura S and Ozaki K., Strength and deformation characteristics
of liquefied stabilized soil reinforced by fiber material prepared at laboratory andfield, Geosynthetic Engineering Journal, 2014, Vol.29, pp.33-40.
Duong H. Q, Kohata Y and Nguyen Q. D., Evaluation on Mitigation of Train-induced
Vibration as Using LSS for Backfilling Ground of Cut and Cover Tunnel by FEM,
the 50th Japan National Conference on Geotechnical Engineering, 2015,
pp.2411-2412.
Do T. A, Kohata, Y. and Sasaki, M., Effect of slurry density on triaxial compressive
properties for liquefied stabilized soil reinforced with fiber material,
Geosynthetics Engineering Journal, 2018, Vol.33, pp.15-22.
Do T. A and Kohata Y., Reduction of vehicle-induced vibration using liquefied stabilized
soil, International Journal of GEOMATE, 2019, Vol. 16, Issue 53, pp.44-46.
Pham Q. V and Kohata Y., Various factors on the strength and deformation property ofliquefied stabilized soil prepared at field, Lecture Notes in Civil Engineering,
2020, Vol. 62, pp.767-774.

92

Cui Y, Kohata Y, and Liu W., Influence of cement solidification agent and slurry density
on mechanical property of liquefied stabilized soil, International Journal of
GEOMATE, 2020, Vol. 19, Issue 73, pp.177-184.
British standard., Eurocode 8: Design of structures for earthquake resistance, BS EN
1998-2004.
SAP 2000 v22., Structural and earthquake engineering software, Computers andStructures, Inc, Berkley, CA.
Ryan K. L and Polanco J., Problems with Rayleigh Damping in Base-Isolated Buildings.
Journal of Structural Engineering, 2008, Vol. 134, Issue 11, pp.1780-1784.
Chopra A. K., Dynamics of structures: Theory and applications to earthquake engineering,
Fourth Edition, Prentice Hall, 2011, p.457.
Rayhani M. H and Naggar M. H. EI., Numerical modeling of seismic response of rigid
foundation on soft soil, International Journal of Geomechanics, 2008, Vol. 8,
Issue 6, pp.336-346.
Rahvar., Geotechnical investigation and foundation design report of Mahshahr train
station, P. O. Rahvar Pty Ltd., Iran Railway Authority, Mahshar, Iran, 2006, pp.142.
Kohata Y, Ito K, and Koyama Y., Effect of cement content on shear properties of liquidstabilized soil reinforced by fiber material, Geosynthetics Engineering Journal,
2011, Vol. 26, pp.95-100 (in Japanese).
Railway Technical Research Institute., Explanation for railway structure and design
standards, 1999.
Kramer S. L., Geotechnical earthquake engineering, Prentice Hall, Upper Saddle River,
NJ, 1996.
Karamodin A.K. and Kazemi H. H., Semi-active control of structures using neuropredictive algorithm for MR dampers, Structural Control and Health Monitoring,
2010, Vol. 17, Issue 3, pp.237-253.
Abaqus 2020 [Computer software]. Dassault Systèmes SIMULIACorporation,
Minneapolis.
Standard Australia., Structural design actions-Part 4: Earthquake actions in Australia,
AS1170.4, Sydney, Australia, 2007.
93

CHAPTER 7
CONCLUSIONS AND SUGGESTIONS

7.1 CONCLUSIONSThis research has carried out both experiments and analyses to investigate thestrength, deformation property, and advantage of Liquefied Stabilized Soil (LSS) and LSS
mixed with fibered material to promote its application backfilling material in undergroundconstruction projects. Firstly, various factors affect the strength and deformation propertyof LSS prepared at field that has been investigated by both laboratory and field testing.
On the other hand, the effects of LSS as backfilling material on the building and groundenvironment under an earthquake were evaluated. Based on the test and analysis results,
the main findings obtained as follow:
1) Various factors affect the strength and deformation property of LSS prepared at fielda) The curing temperature could affect the deviator stress q of LSS without fiber
material. As for LSS with fiber material, there is an independence of the deviator
stress q on the curing temperature when curing days increases. The brittle propertyof LSS without fiber material has been improved by the reinforcement effect ofadding fiber material. It is found that aseismic performance in the ground is
improved and toughness ground will be constructed when the LSS with fiber
material is using as backfilling.
b) The effect of curing temperature is smaller than that of curing days on

InitialYoung’s modulus E0.
c) The effect of adding the fiber material on LSS increases the non-linearity of
deformation property in q~εa relation while the curing temperature has been lower.
d) During the first period of the curing process of LSS mixed fiber material, theaddition of the fiber material into LSS is reduced the damage degree during shear.
However, there is unclear when the number of curing days increases and the94curing temperature drops significantly. For this result, it considered conducting
further works the next time.
e) The K-value by portable FWD can be evaluated the stiffness of backfilling groundby LSS with fibered material adequately.
2) The effects of LSS as backfilling material on the building and ground environment
under an earthquakea) Using LSS with fiber and LSS as a backfilling material will slightly reduce thelateral displacement and inter-story drift of the building under the impact of theearthquake.
b) The application of LSS with fiber and LSS as a backfill material will significantly
decrease the acceleration and velocity of the ground around the building andadjacent areas when the earthquake occurs.
c) The effect of fiber material, when mixed with LSS, was made clear in this study.
LSS mixed with fiber has more advantageous than LSS.
d) It is considered that the LSS and LSS with fiber have an effective potential toreduce the seismic motion on the buildings and the surrounding soil environment.
This property is a new advantage of LSS and LSS with fiber.
7.2 RECOMMENDATIONSWith the conclusions and findings of this research, several suggestions for future
work can be given as follows:
Due to the complicated climate in Japan, summers are hot, and winters are
freezing, especially in Hokkaido. Therefore, it is necessary to carry out many field tests
under extreme conditions such as the test sample being cured for a long time whensnowfall (temperature in the ground will increase dramatically), then the snow melts(temperature significant reduction). The strain strength and deformation property of the
LSS at each time should be checked and compared. From there, the impact of theenvironment on LSS is investigated.
Different types of loading should be considered to apply in the triaxial
compression test. For example, cyclic loadings are necessary to investigate the behaviorof LSS when using as backfilling material to cover the tunnel railway.

95

Numerical models of LSS applications under real construction conditions andspecial loads should be conducted in the future to find out more advantages of LSS topromote the strong use of LSS in construction.
There is still a lot of work worthy of being done in the future to investigate thedeformation property of LSS in more detail. With these efforts, we surely believe that thismaterial could have wide utilization in the future.

96