ハノイ市における埋戻し材としての繊維材混合流動化処理土の利用促進に関する研究
メタデータ

言語: English
出版者:
公開日: 2019-06-25
キーワード (Ja):
キーワード (En):作成者: ドゥ, トゥアン アン
メールアドレス:所属:

URL

https://doi.org/10.15118/00009906

Study on Promoting Use of Liquefied Stabilized Soil mixed
Fiber Material as Backfilling Material in Hanoi City
By
DO TUAN ANH

A DISSERTATION SUBMITTED TO THE FACULTY OF THE
MURORAN INSTITUTE OF TECHNOLOGYIN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF ENGINEERING

Division of Civil and Environmental Engineering
MURORAN INSTITUTE OF TECHNOLOGY
March 2019Acknowledgments
Firstly, I would like to express my sincere gratitude to my advisor Professor. Yukihiro
Kahata for the continuous support of my Ph.D study and related research, for his patience,motivation, and immense knowledge. His guidance helped me in all the time of research
and writing of this thesis. I could not have imagined having a better advisor and mentor
for my Ph.D study.
Besides my advisor, I would like to thank the rest of my thesis committee: Associate
Professor Dr. Shima Kawamura and Associate Professor Dr. Noriyuki Sugata, for theirinsightful comments and encouragement, but also for the hard question which incented me
to widen my research from various perspectives.
Special I am grateful to Dr. Duong Quang Hung for his introduction andrecommendation to Muroran Institute of Technology and Professor Kohata before I applied
for study here.
My sincere thanks are due to Mr. Funamizu Naoyuki and all the staffs of the Centre forInternational Relations, Muroran IT, Mr. Jinro Endo, Ms. Baek Sangyub, and Ms. Hatsuki
Noda for making my life in Hokkaido really comfortable and enjoyable. They always
extended instant help whenever I needed. Especially thanks to Associate Professor Naoko
Yamaji’ teaching, my Japanese has been improved much.
I thank my fellow labmates in for the stimulating discussions, for the sleepless nights
we were working together before deadlines, and for all the fun we have had in the last three
years. In particular, I am grateful to Dr. Nguyen Cong Giang for enlightening me the firstglance of research.
I am indeed indebted to my friends who assisted in life during three years of my doctor
course, Mr. Mona Yuttana, Mr. Khongma Saysrath, Mr. Teerawat Kumrai and International
friends, and Japanese friends. Thanks to everyone.
Further, I also sincerely thank Associate Professor Dr. Vuong Ngoc Luu of the Hanoi
Architectural University (HAU) for offering me recommendation letters to apply for the
doctor course.
Last but not the least, I would like to thank my family: my wife, Ms. Nguyen Thi Lan
Anh, my son, Do Cong Gia Phuc, and my daughter, Do Ngoc Minh Chau for supportingme spiritually throughout writing this thesis and my life in general.

iAbstract
In this study, the applicability of Liquefied Stabilized Soil (LSS) mixed with the fiberedmaterial as the backfill materials at Hanoi city in Vietnam has been investigated. Researchworks including experiment and analysis have been conducted simultaneously aiming topromote the application of LSS in Hanoi city in the coming time. This study is summarized asfollows.
(1) The influence of slurry density on strength and deformation characteristics of LSS
mixed with fibered 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 fibered 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.
(2) The difference in triaxial shear property of LSS mixed with fiber material cured inlaboratory 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 by block sampling and cured in laboratory at curing timeof 28 and 56 days, respectively. Based on the test results, it was found that the qmax in q~arelations of LSS mixed with fiber material cured at field tend to be larger than that cured inlaboratory.
(3) A procedure for prediction of vehicle-induced vibration from a road surface has been
established as a case study for a general road in Hanoi city in conformity with VietnameseStandard. The vibration propagation from a road surface was analyzed by the 2-D FEM. The
numerical results in terms of vibration velocity allow estimating the vibration velocity level,
and then it is applicable to the prediction of vehicle-induced vibration. The calculated vibration
velocity level on backfilling sandy soil indicated to be higher than the allowable threshold,therefore appropriate measures should be taken to decrease these vibrations.
(4) According to the numerical analysis results on a mitigation of vehicle-induced vibrationin case using LSS as backfill material by the established analysis method, it is found that theapplication of LSS can reduce the ground vibration. This will be a new advantage. Then, it isconsidered that the application to backfilling ground of LSS become one of effective measure
for reduction of vehicle-induced vibration. Therefore, it is considered that the application of
the LSS mixed with fibered material as backfilling material will be more promoted in Hanoi
city.
ii

Table of Contents

Acknowledgments .....................................................................................................................................................................i
Abstract ..............................................................................................................................................................................................ii
List of Tables................................................................................................................................................................................................... vi
List of Figures ...............................................................................................................................................................................vii
Chapter 1 INTRODUCTION ............................................................................................................................................... …1
1.1.

GENERAL BACKGROUND ............................................................................................................ 1

1.2.

MOTIVAION FOR RESEARCH ................................................................................................... 3

1.3.

OBJECTIVE OF RESEARCH ......................................................................................................... 3

1.4.

ORGANIZATION OF THESIS........................................................................................................ 7

Chapter 2 OVERVIEW OF LIQUEFIED STABILIZED SOIL ............................................... ..10
2.1.

INTRODUCTION........................................................................................................................................ 10

2.2.

COMPONENT OF LIQUEFIED STABILIZED SOIL ................................................ 11

2.2.1

Soil .................................................................................................................................................................................... 11

2.2.2

Cementitious materials ..................................................................................................................................... 11

2.3.

HISTORICAL DEVELOPMENT ................................................................................................... 14

2.4.

APPLICATIONS ...................................................................................................................................................... 19

2.5.

SITUATION OF BACKFILLING PROCESS IN VIETNAM ............................... 22

2.5.1

Problem of backfilling method in Vietnam ................................................................................... 22

2.5.2

Inappropriate disposal of excavated soils......................................................................................... 23

2.5.3

Mining of new material from natural resources .......................................................................... 24

2.6.

UTILIZATION OF LSS IN VIETNAM .................................................................................... 22

2.7.

SUMMARY .................................................................................................................................................................. 26

Chapter 3 INFLUENCE OF SLURRY DENSITY ON PROPERTIES OF LSS.............29
3.1.

INTRODUCTION ...................................................................................................................................................29

3.2.

TEST PROCEDURE ................................................................................................................................. 31

3.2.1

Test material.............................................................................................................................................................. .31

3.2.2

Mixing method ....................................................................................................................................................... .31

3.2.3

Specimen preparation........................................................................................................................................ .33
iii

3.2.4

Test method ................................................................................................................................................................ 34

3.3.

TEST RESULTS AND DISCUSSION ....................................................................................... 35

3.3.1

Relationship between deviator stress and axial strain. ........................................................... 35

3.3.2

Deformation property ........................................................................................................................................ 39

3.4.

CONCLUSIONS ........................................................................................................................................... 44

Chapter 4 METHODS FOR DETERMINING DYNAMIC PARAMETERS OF
SOIL ........................................................................................................................................................................... ..46
4.1.

INTRODUCTION........................................................................................................................................ 46

4.2.

UTILITY OF MEASURED PARAMETER........................................................................... 461) Shear wave velocity (Vs) ............................................................................................................................................46
2) Shear modulus (G) ...................................................................................................................................................... 47
3) Maximum Shear Modulus (Gmax)........................................................................................................................47
4) Damping Ratio (h) ...................................................................................................................................................... 47
5) Poisson’s Ratio (n) ...................................................................................................................................................... 48
4.3.

GEOTECHNICAL APPROACHES TO DETERMINE DYNAMIC SOILSPROPERTIES.............................................................................................................................................................. 48

1) Seismic Refraction................................................................................................................................................................ 48
2) Cross-Hole Technique ...................................................................................................................................................50
3) Down-Hole Techniques ...............................................................................................................................................51
4) Up-Hole Techniques .......................................................................................................................................................53
5) Steady-State Surface Wave Technique ........................................................................................................ 54
6) Spectral Analysis of Surface Waves (SASW) ....................................................................................... 55
7) Seismic Cone Penetration Test (SCPT) ..........................................................................................................56
8) Suspension PS logging ............................................................................................................................................ 57
4.4.

ESTIMATION OF DYNAMIC SOIL PROPERTIES .................................................... 59

4.5.

SUMMARY .................................................................................................................................................................. 65

Chapter 5 STUDY ON VEHICLE-INDUCED VIBRATION ......................................................... ..67
5.1.

INTRODUCTION........................................................................................................................................ 67

5.2.

DEFINITION OF VIBRATION LEVEL .................................................................................. 68

5.3.

ANALYTICAL AND NUMERICAL APPROACHES ................................................. 69

5.3.1

Vehicle motion......................................................................................................................................................... 69

5.3.2

Road Spectrum ........................................................................................................................................................ 69

5.3.3

Vehicle loads on pavement ............................................................................................................................ 70iv

5.3.4Cyclic vehicle loading spectrum .............................................................................................................. 70

5.3.5

Generation of a time history of cyclic vehicle loading .......................................................... 71

5.3.6

Verification ................................................................................................................................................................. 71

5.4.
5.4.1
5.5.

ANALYSIS PROCEDURE .................................................................................................................. 72
Selection of material model.......................................................................................................................... 73
NUMERICAL MODEL AND CONSIDERED PARAMETERS ......................... 76

5.5.1

Road and ground conditions ........................................................................................................................ 76

5.5.2

Finite element model.......................................................................................................................................... 77

5.6.

SUMMARY .................................................................................................................................................................. 77

Chapter 6 REDUCTION OF VEHICLE-INDUCED VIBRATION USING
LIQUEFIED STABILIZED SOIL ............................................................................................. ...80
6.1.

INTRODUCTION ................................................................................................................................................... 80

6.2.

ANALYSIS PROCEDURE .................................................................................................................. 81

6.2.1

Simulation of cyclic vehicle load ............................................................................................................ 81

6.2.2

Numerical model and considered parameters ............................................................................... 81
1- Building, road and ground conditions ....................................................................................81
2- Characteristics of backfilling materials .................................................................................83
3- Finite element model............................................................................................................................85
4- Numerical model in Plaxis ..............................................................................................................85

6.3.

RESULTS AND DISCUSSION........................................................................................................ 86

6.3.1

Vibration acceleration in Case 1 and Case 2 .................................................................................. 87

6.3.2

Relationship between distance maximum vibration velocity and level ................... 87

6.4.

CONCLUSIONS ........................................................................................................................................... 88

Chapter 7 CONCLUSIONS AND RECOMMENDATIONS .......................................................... ..91
7.1.

SUMMARY OF INVESTIGATIONS ......................................................................................... 91

7.2.

SUMMARY OF FINDINGS AND CONCLUSIONS ................................................... 92

7.3.

RECOMMENDATIONS FOR FUTURE RESEARCH .............................................. 93v

List of Tables
Table 1.1 Test conditions of axial strain rate .................................................................................................... 5
Table 1.2 The comparison between the previous study and this study ........................................ 6
Table 3.1 Physical Properties of NSF-CLAY .................................................................................................. 31
Table 3.2 Result of density test.................................................................................................................................... 32
Table 4.1 SPT (N*60) – Shear Wave Velocity, vs, Equation for Sand
(Andrus et al., 2003) .................................................................................................................................................... 60
Table 4.2 Recommended Age Scaling Factors (ASF) for SPT(Andrus et al., 2003) ................................................................................................................................................ 60
Table 4.3 CPT (qc) – Shear Wave Velocity, vs, Equations for Soils(Andrus et al., 2003) ............................................................................................................................................... 61
Table 4.4 Recommended Age Scaling Factors (ASF) for CPT(Andrus et al., 2003) ................................................................................................................................................ 62
Table 5.1 Material properties of road ..................................................................................................................... 76
Table 5.2 Geotechnical properties of soil layers ............................................................................................ 76
Table 6.1 Parameters of building ............................................................................................................................... 82
Table 6.2 Geotechnical properties of soil layers ............................................................................................ 82
Table 6.3 Material properties of road ..................................................................................................................... 84
Table 6.4 Physical properties of backfilling materials .............................................................................. 85vi

List of Figures
Figure 1.1 Motorbikes and scooters on the streets of Hanoi city ......................................................... 1
Figure 1.2. Smoke created by burning waste in a street in Hanoi city .......................................... 2
Figure 1.3 Metro rout map of Hanoi city up to 2030 .................................................................................. 2
Figure 1.4 q~εa relation of Vinh Phuc-Clay LSS ........................................................................................... 5
Figure 1.5 q~εa relation of NSF -Clay LSS ........................................................................................................ 5
Figure 1.6 Flow chart of this dissertation ............................................................................................................ 7
Figure 2.1 Flow of Liquefied soil stabilized method (Tomoharu et al., 2005) ...................... 17
Figure 2.2 Cement treated soil using as slope protection (Tang et al., 2001)........................... 17
Figure 2.3 Production system for foam mixed lightweight soil ............................................................18
Figure 2.4 Placement of cement treated soil along slope (Tang et al., 2001) ........................... 18
Figure 2.5 Placement of cement treated soil along slope (Tang et al., 2001) ........................... 18
Figure 2.6 Use of LSS for filling cavity under road surface .................................................................. 18
Figure 2.7 LSS used for backfill at upper part of cut and cover tunnel.......................................... 19
Figure 2.8 LSS used for invert material of shield tunnel .......................................................................... 20
Figure 2.9 Using LSS for various backfilling works in Japan.............................................................. 21
Figure 2.10 Cave-in and road collapses in Hanoi city ................................................................................ 22
Figure 2.11 inappropriate disposal of excavated soils from construction sites in
Hanoi........................................................................................................................................................................ 23
Figure 2.12 Bank erosion due to depletion of sand in streambed ...................................................... 24
Figure 3.1 Available range of slurry density ...................................................................................................... 32
Figure 3.2 Schematic drawing of pits ...................................................................................................................... 34
Figure 3.3 Schematic figure of test apparatus ................................................................................................... 34
Figure 3.4 qεa relations up to 3 % .................................................................................................................. 37
Figure 3.5 qεa relations up to 0.5 % .................................................................................................................... 38
Figure 3.6(a) qmaxcuring days relations for Field LSS ................................................................. 38
Figure 3.6(b) qmaxcuring days relations for Laboratory LSS .................................................. 39
Figure 3.7. Definition of various Young’s moduli ............................................................................................ 39
Figure 3.8(a) E0curing days relations for Field LSS ................................................................ 41vii

Figure 3.8(b) E0curing days relations for Laboratory LSS ................................................. 41
Figure 3.9 Etan/E0q/qmax relations................................................................................................................... 42
Figure 3.10 Eeq/E0~q/qmax relations............................................................................................................................ 44
Figure 4.1 Field and laboratory methods for determining dynamic parameters...................... 49
Figure 4.2 Cross-hole method........................................................................................................................................ 52
Figure 4.3 Down-hole method....................................................................................................................................... 53
Figure 4.4 Up-hole method .............................................................................................................................................. 54
Figure 4.5 Steady-State Surface Wave Test ....................................................................................................... 55
Figure 4.6 Seismic Cone Penetration Test ........................................................................................................... 57
Figure 4.7 - Suspension PS Logging test .............................................................................................................. 58
Figure 4.8 h relation of sandy soils (PI = 0 %) ................................................................................................. 64
Figure 4.9 h relation of sandy soils (PI = 35 %) ........................................................................................... 65
Figure 5.1 Relationship between maximum cyclic vehicle load and the grade of surfaces
on roads of various classes ....................................................................................................................72
Figure 5.2 Schematic diagram of prediction procedure for train-induced vibration fromroad..................................................................................................................................................................... 73
Figure 5.3 Cam-Clay model parameters in Plaxis.......................................................................................... 75
Figure 5.4 Mohr-Coulomb model parameters in Plaxis ............................................................................ 75
Figure 5.5 Finite element model in Plaxis ........................................................................................................... 77
Figure 6.1 Numerical model of the considered soil structure system ................................................ 82
Figure 6.2 Ground profile ................................................................................................................................................. 83
Figure 6.3 Typical cross section of Giai Phong road ...................................................................................... 83
Figure 6.4 Finite element model in Plaxis ........................................................................................................... 84
Figure 6.5 Vertical acceleration at point E for load amplitude =400 kN/m,
f = 10 Hz ........................................................................................................................................................86
Figure 6.6 Horizontal acceleration at point E for load amplitude =400 kN/m,
f = 10 Hz ....................................................................................................................................................... 86
Figure 6.7 Vertical acceleration at point H for load amplitude =400 kN/m, f = 10 Hz ... 86
Figure 6.8 Horizontal acceleration at point H for load amplitude =400 kN/m,
f = 10 Hz .........................................................................................................................................................86
Figure 6.9 Distance and maximum velocity ....................................................................................................... 86
Figure 6.10 Distance and maximum vibration level .................................................................................... 86
viii

Chapter 1

INTRODUCTION

1.1. GENERAL BACKGROUND
Viet Nam is experiencing rapid urbanization and motorization owing to economic
development after the introduction of “Doi Moi” policy. Urban transportation problems
such as traffic congestion and air pollution are becoming important challenges for thenation’s two major cities of Hanoi and Ho Chi Minh. This study outlines the current status
and issues of motorcycle-dominated urban transportation in both cities, reviews thepresent regulatory framework regarding the bus transportation, and recommends theregulatory improvements for the promotion of public transportation.
At present, Hanoi city of Vietnam, a city with more motorbike than households, has
to contend with heavy congestion, air pollution and frequent traffic accidents. In recent
years, Hanoi city has been ranked one of the worse cities in Asia for air pollution. In May
2017, US embassy’s quality monitor in Hanoi city had registered a hazardous spike inparticular mater, reaching a level seven times according to recommendation of the World
Health Organization. In addition, Hanoi’s population jumped from about 2.7 million in2000 to about 3.2 million in 2006 (and is expected to reach 4.5 million in 2020), resulting

Figure 1.1 Motorbikes and scooters on the streets of Hanoi city1

CHAPTER 1

INTRODUCTION

Figure 1.2 Smoke created by burning waste in a street in Hanoi city
in a dramatic increase in traffic volume on city roads and severe traffic congestion.
The current situation need to be solved as soon as possible. The solutions were given
including expanding the transport capacity of existing public transportation and road
networks, a new urban mass rapid transit system. Therefore, plan of Railway Construction
was formed in 2002 to aim modernization of rail transport. Hanoi’s Transport Plan aims
to increase the share of public transport from the current low figure of 9% of trips, toabove 60% by 2030, by which time Hanoi is slated to have six new metro lines and three
Bus Rapid Transit (BRT) lines as shown in Figure 1.3. Vietnamese government hopes
the metro can tackle both traffic and environmental issues.

Figure 1.3 Metro rout map of Hanoi city up to 2030
2

CHAPTER 1

INTRODUCTION

However, it is predicted that a huge quantity of excavated soil will be discharged fromthe underground construction projects in the city over the next decade. In addition, atpresent, excavated soils from construction sites are disposing inappropriate due to theshortage of landfill sites in the cities. Whereas, most backfilling material for construction
works is being extracted from natural sources such as sand mining from river and gravelfrom mountain, which cause significantly negative impact on environment. On the other
hand, during operating the metro systems, ground-born vibration is caused by train-track
structure exciting the tunnel, adjacent soil layers. Created waves propagate to thefoundations of nearby building and annoying to nearby resident. In Vietnam, standards orliteratures have been not found to predict ground-born vibration until now. Therefore,
environmental impact assessment and the dynamic parameters of soil have been notestimated clearly.
1.2. MOTIVAION FOR RESEARCH
In order to handle excavated soil from the construction projects, developed countries
have applied recycling methods for excavated soil and Japan has always been at theforefront of the development of science and technology. One of recycling methods beenused popularly for excavated soil is Liquefied Stabilized Soil (LSS), which the soil ismixed with water (or muddy water) and cement stabilizer and reused as backfillingmaterial (Kuno, 1997; JGS, 2005). LSS will be effective methods to solve the problemsof soil generated from construction sites and shortage of backfilling material in Vietnam.
LSS will be useful not only for construction of transport infrastructure Projects, butalso design of geotechnical engineering and also for new direction of development ofscience and technology during development of geotechnical projects in Vietnam.
1.3. OBJECTIVE OF RESEARCHIn Muroran institute of technology, Prof. KOHATA Yukihiro and researchers at
Geotechnical engineering Laboratory of Muroran Institute of Technology have continued
to study and develop LSS. Although utilities of LSS during recycling excavated soil havebeen shown, LSS indicates a brittle characteristic with an increasing of strength and adecreasing of aseismatic performance similar to cement stabilized soil. Therefore, theimprovement of this property of LSS is very important task. In order to improve ductile
performance of LSS, Professor KOHATA et al have carried out the method to be mixing
LSS with crushed newspaper fibered material. From the test results, it was shown that a3

CHAPTER 1

INTRODUCTION

brittle property after the peak was improved by mixing with crushed newspaper.
The previous research in 2010 performed with both LSS using NSF-clay which is fine
powder clay bought in Japanese market and Vinh Phuc-Clay which spread in Hanoi area
as an original material, it concluded that the strength and deformation behaviors of both
LSS tend to be similar (Giang, 2010). Figure 4 and Figure 5 show the relationship between
deviator stress q (=σσ ) and axial strain ε from Consolidated–Undrained triaxial

compression tests under confining pressure σ = 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.
The tests were performed under axial strain rate of 0.054 %/min. Thus, the behaviors ofboth LSS is the same. Also, the other results of the research indicated that the physicalbehaviors 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 = 98 kPa had
been performed with four different conditions of axial strain rate shown in Table 1. (Hung,2015). The specimens had been cured under conditions of indoor and outdoor,
respectively. The results of the research indicated that (1) the maximum deviator stress,
qmax in q~ ε

curve of LSS mixed with fibered material indicates similar value

independently of curing days. However, in case of LSS without fibered material, there isa tendency to increase the initial stiffness as increasing of curing days; (2) the range ofindicating 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; (3) the rigidity duringloading before the peak in q~ε relationship increases temporarily in a large strain level
after a creep stage and a change of strain rate independently of curing days. In addition,a procedure for prediction of train-induced vibration form railway tunnels in conformity
with condition of Vietnam has been established as an example for Hanoi metro line. The
vibration propagation from tunnel into the ground surface was analyzed by twodimensional element method (2-D FEM). And then, the established procedure was used
to evaluate train-induced vibration as using LSS for backfilling ground of cut and covertunnel. The results has shown that the LSS could reduce train-induced vibration fromtunnel.

4

CHAPTER 1

INTRODUCTION

500

350

450
300

Deviator stress , q (kPa)

Deviator Stress, q (kPa)

400
350
300
250
200
150

98 kPa100
50

0 kg/m3
10 kg/m3
20 kg/m3

56 days
2

4

6

8

10

12

200
150
100

98 kPa3

10 kg/m
3
10 kg/m
3
20 kg/m50

56 days

0
0

250

0

14

Axial Strain, εa (%)

0

2

4

6

8

10

12

14

Axial Strain ,a(%)

Figure 1.5 q~εa relation of Vinh Phuc-Clay LSS

Figure 1.5 q~εa relation of NSF -Clay LSS

Table 1.1 Test conditions of axial strain rate
Case 1

0.054 % min 𝑒

Case 20.54 % min 10𝑒

Case 3𝑒 → 10𝑒 → 𝑒Case 4𝑒 → 𝐶 → 𝑒 → 𝐶 → 10𝑒 → 𝐶 → 𝑒※Creep applied before rate change

In this study, in order to investigate influence of slurry density on strength anddeformation properties of LSS reinforced with fiber material, NSF-clay was used as apresentative of LSS using excavated soil. In addition, to evaluate reduction of traininduced building vibrations by using LSS for back filling. The objective of this study isto promote using LSS mixed fiber material as backfilling material in Ha Noi city, Vietnam.
The first of all, the effect of slurry density on strength and deformation property of
LSS reinforced with small strain level of different densities of specimens preparedlaboratory was discussed. The influence of density on strength and deformation
characteristics of LSS mixed with paper was investigated. On the other hand, in order toanalyze effect of the slurry density when LSS mixed with fiber material worked on
condition of field reality, four test pits were built and were filled up by LSS mixed withfibered material at test field in Muroran-IT campus. Their length is 50 centimeters, theirwidth is 40 centimeters and their deep is 30 centimeters. These test pits were constructedwith different densities of LSS mixed fiber material. These pits were cured under natural
5

CHAPTER 1

INTRODUCTION

condition. And then, the in-situ compressive stiffness of the LSS was evaluated and thenon-uniformity of back fill ground by LSS mixed with fibered material was discussed bycomparing the results between laboratory tests and field tests.
Secondly, methods for estimation of soil dynamic parameters in conformity withcurrent condition of Vietnam was suggested by selectively adopting the methods ofprevious researches in the world. Then, a procedure for prediction of vehicle-induced
vibration from road in Vietnam was fully established. The road in Hanoi city currently
near the building was selected to analysis in this study. Vehicles-induced dynamic loading
to building was simulated by means of vehicles-road-ground interaction model. Resultsof the simulation in term of force time history was input data for vehicles-soil interaction
problem. The vibration propagation from vehicles on the road was analyzed by the 2dimensional finite element method (FEM). Numerical results from the model in term ofvibration velocity allow estimating the vibration velocity level, and then it is applicableto the prediction of vehicles-induced vibration propagated from road.
Finally, reduction of vehicles-induced vibration as using LSS for backfilling groundwas evaluated by using established procedure. This study analyzed 2 cases including LSS
and backfilling soil as backfilling material for area near building.

Table 1.2 The comparison between the previous study and this study
Previous study

This study

Density of slurry Content of fiber material

Density of slurry

Content of fiber material(g/cm3)(kg/m3)(g/cm3)(kg/m3)

1.280

0 and 20

1.280 and 1.216

0 and 106

CHAPTER 1

INTRODUCTION

1.4. ORGANIZATION OF THESISStudy on promoting use of LSS mixed fiber material as backfill
material in Hanoi city

Chapter 1
Introduction

Chapter 2
Overview of LSS

Chapter 3
Influence of slurry density on properties of LSS

Chapter 4
Methods for determining dynamic parameters of soil

Chapter 5
Study on vehicle-induced vibration

Chapter 6
Reduction of vehicle-induced vibration using LSS

Chapter 7
Conclusions and Recommendations

Figure 1.6 Flow chart of this dissertation

7

CHAPTER 1

INTRODUCTIONAs seen in Figure 1.6, this dissertation contains seven chapters. The introduction(Chapter 1) describes the general background, objectives and scopes of research andorganization of the dissertation.
Chapter 2 presents an overview of LSS as an effective method for utilization of
excavated soil. The problems regarding excavating works in Vietnam was pointed out andthen feasibility for utilization of LSS in Vietnam has been highlighted in this chapter.
Chapter 3 is to investigate influence of slurry density on deformation and strengthcharacteristics of LSS by triaxial compression tests. Two slurry densities were preparedand then they were cured in laboratory and at field, respectively.
Chapter 4 present methods for determining dynamic parameters of soil. Methods for
estimation of soil dynamic parameters in conformity with current condition in Vietnam issuggested in the chapter. Use of the methods in order to estimate soil dynamic parameters
for backfilling site in Hanoi bring reliable results.
Chapter 5 establishes fully a procedure for prediction of vehicle-induced vibration inbackfilling ground in Ha Noi city, Vietnam.
Using the established procedure, chapter 6 evaluates the reduction of vehicle-induced
vibration as using LSS for backfill ground of building in Hanoi city.
Finally, the conclusions drawn from this study and recommendations for future works
were given in chapter 7.
REFERENCES
Luu, D. H. (2010): Metro-a mode of indispensable public transportation in big cities,
Journal of Vietnam federation of civil engineering association (in Vietnamese).
Kuno, G., eds (1997): Liquefied stabilized soil method-Recycling technology ofconstruction-generated soil and mud, Gihodo publication (in Japanese).
Japanese Geotechnical Society (2005): Committee Report Chapter 2, 2.1, 2.2 on test
methods and physical properties of cement-modified soil, Proc. of symposium, pp.2-22,
on survey, design, construction and properties evaluation methods of solidifying
stabilized soil using cement and cement-treated soil (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): Strengthand deformation 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).

8CHAPTER 1

INTRODUCTION

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 to triaxial
shearing, Geosynthetics Engineering Journal, Vol.22, 55-62 (in Japanese).
Ito, K., Kohata, Y., and Koyama, Y. (2011): Influence of additive amount of cement
solidification agent on mechanical characteristics of Liquefied Stabilized Soil mixed withfibered material, Japanese Geotechnical Society Hokkaido Branch Technical Report
Papers, Vol.51, 131-136 (in Japanese).
Giang, N. C. (2010): Study on advanced effective utilization of excavated soil in Hanoi
city – Vietnam, a thesis, division of civil and environmental engineering; graduate schoolof Muroran Institute of technology.

9Chapter 2

OVERVIEW OF LIQUEFIED STABILIZED SOIL

2.1.

INTRODUCTION

The soil stabilization is process improving if geotechnical properties to stratify
engineering requirements. Until now, numerous kinds of stabilizers including cement,
lime and fly ash etc. were used as soil additives to improve its properties. The LSS
manufacturing process utilizes soil which has been excavated in construction projects andwhich would otherwise be discharged to natural environment as soil waste. LSS can beused for confined spaces or excavation areas and it can be easily placed without vibrationand compaction. The characteristics, benefits, advantages and applications of LSS has
been shown such as:Characteristics:-

Impermeability

Benefit:-

Reduce cost of construction projects-

Reduce manpower-Protect environment

Advantage:-

Excavated out easily-

Quick setting time-

Convenient compared to normal backfilling-

Faster than normal backfilling-

No soil stockpile needed

Application:-

Backfill sing concrete pump
10

CHAPTER 2

2.2.

OVERVIEW OF LIQUEFIED STABILIZED SOIL

Cavities and excavated trenches can be backfilled easily
COMPONENT OF LIQUEFIED STABILIZATION SOIL

Liquefied stabilized soil involves the use of binder materials in soils to improve its
geotechnical properties such as compressibility, strength, permeability, flexibility anddurability. The components of liquefied stabilized soil include soils, binders (cementitious
materials).

Soils+ Water +Binders

2.2.1. Soil
Most soils in liquefied stabilized soil method are soft soils. The stabilization has been
performed to achieve desirable engineering properties. The main purpose of liquefied
stabilized method is to recycle excavated soil for backfilling processes for construction
projects. Therefore, almost types of excavated soils can be used for this method. However,fine-grained granular materials are the easiest to stabilize due to a large surface area in
their contact diameter. The excavated soils can be modified to perform mainly with the
purpose of improving their usability in construction. At present, excavated soils arestabilized by binders which are selected in relation to the type of soil. The stabilization
has improved the strength of the soils and their resistance to softening.
2.2.2. Cementitious materials
In stabilizing a soil, these are hydraulic (primary binders) or non-hydraulic (secondary
binders) materials that when in contact with water or in the presence of pozzolanic
minerals reacts with water to form cementitious composite materials. The commonly usedbinders are: cement, lime or fly ash. In order to decide which binder should be used, theanalysis have be performed based on test results and in fact condition of projects.
1. Cement
Cement had been known as the binding agent since the invention of soil stabilization
technology in the 1960’s. It may be considered as primary stabilizing agent or hydraulicbinder 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 a11

CHAPTER 2OVERVIEW OF LIQUEFIED STABILIZED SOIL

wide range of soils. Numerous types of cement are available in the market; these areordinary Portland cement, blast furnace cement, sulfate resistant cement and high alumina
cement. Usually the choice of cement depends on type of soil to be treated and desired
final strength. Hydration process is a process under which cement reaction takes place.
The process starts when cement is mixed with water and other components for a desired
application resulting into hardening phenomena. The hardening (setting) of cement will
enclose soil as glue, but it will not change the structure of soil. The hydration reaction isslow 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 presence of
foreign matters or impurities, water-cement ratio, curing temperature, the presence ofadditives, and specific surface of the mixture.
2. LimeLime is the oldest traditional stabilizer used for soil stabilization. Lime-treated soil
was studied extensively in the literature. Numerous field and laboratory studies wereconducted to evaluate the improvement of geotechnical properties by lime. Several typesof soils, lime contents and curing conditions and methodologies were used for thispurpose. The mechanism of treatment comprised hydration, cation exchange,
flocculation-sagglomeration 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, curing time, curing
temperature and soil mineralogy. Soil-lime mixtures have advantages and disadvantages.
Its advantages comprise significantly increase soil strength, reduce plasticity (increase
workability) and increases soil durability. In addition, 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 environment impact are a numberof the disadvantages of lime-treated soil. Some studies were conducted to provide
some guidelines to reduce the deleterious effects of these cons. Magnesium oxide andhydroxide can be proposed as alternative for lime since they possess chemical
characteristics make them eligible to overcome the mentioned cons. Moreover, the resultof few conducted studies used magnesium based additives to stabilize the soil was
significant improvement achieved in soil strength, workability and durability. Therefore,
12CHAPTER 2OVERVIEW OF LIQUEFIED STABILIZED SOIL

it is need to conduct extensive studies to determine the efficiency of this material in soil
stabilization.
3. Fly ash
Fly ash has been used successfully in many projects to improve the strengthcharacteristics of soils. Fly ash can be used to stabilize bases or subgrades, to stabilize
backfill to reduce lateral earth pressures and to stabilize embankments to improve slope
stability. Typical stabilized soil depths are 15 to 46 centimeters. The primary reason fly
ash is used in soil stabilization applications is to improve the compressive and shearing
strength of soils. The compressive strength of fly ash treated soils is dependent on:-

To enhance strength properties-

Stabilize embankments-

To control shrink swell properties of expansive soils-

Drying agent to reduce soil moisture contents to permit compaction

Class C fly ash can be used as a stand-alone material because of its self-cementitious
properties. Class F fly ash can be used in soil stabilization applications with the additionof a cementitious agent (lime, lime kiln dust, CKD, and cement). The self-cementitious
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 and water(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 not alone provide a basis
to evaluate the potential interactions between the fly ash and soil or aggregate.
The use of fly ash in soil stabilization and soil modification may be subject to local
environmental requirements pertaining to leaching and potential interaction with groundwater and adjacent water courses.
Soil Stabilization to Improve Soil Strength13CHAPTER 2OVERVIEW OF LIQUEFIED STABILIZED SOIL

Fly ash has been used successfully in many projects to improve the strengthcharacteristics of soils. Fly ash can be used to stabilize bases or subgrades, to stabilize
backfill to reduce lateral earth pressures and to stabilize embankments to improve slope
stability. Typical stabilized soil depths are 15 to 46 centimeters (6 to 18 inches). The
primary reason fly ash is used in soil stabilization applications is to improve thecompressive and shearing strength of soils. The compressive strength of fly ash treatedsoils is dependent on:-

In-place soil properties-

Delay time-

Moisture content at time of compaction-

Fly ash addition ratio

2.3.

HISTORICAL DEVELOPMENT

The original concept comes from the United States, soil mixing was first developed
by Intrusion-Prepakt, Inc. of Cleveland Ohio (Liver et al. 1954) as “Intrusion Grout
Mixed-in-Place Piles”.
In 1961, the mixed in place already used under license for more than 300 000 lineal
meters of piles in Japan for excavated support and groundwater control. Continued until
early 1970’s by Seiko Kogyo Company, to be suggested by diaphragm walls and deep
mixing method (Soil-Mix Wall). In addition, Herrin and Mitchen (1961) suggested that
there is no one of optimum lime content with which maximum strength of lime stabilizedsoils can be expected under all condition. That is, for a specific condition of curing tineand soil type an optimum lime content which caused a maximum strength exists.
The development and research on deep mixing started from laboratory model tests in1967 by the Port and Harbour Research Institute of Japanese Ministry of Transportation.
Research was continued by Okumura, Terashi et al. through 1970’s including 1investigation of lime-marine reaction, and 2- develop appropriate mixing equipment.
Unconfined compressive strength (UCS) of 0.1 to 1 MPa achieved. Early equipment(Mark I-IV) used the first marine trial near Hamada Airport (10 m below water surface).
In addition, Swedish Lime column method for treating soft clays under embankment
using unslaked lime was researched (Kjeld Paus, Linden- Alimak AB, in cooperation with
Swedish Geotechnical Institute, Euroc AB, and BPA Byggproduction AB). And then, thisfollows observations by Paus on fluid lime column installation in the United State.
14

CHAPTER 2OVERVIEW OF LIQUEFIED STABILIZED SOIL

In the late 1960’s, China reported to be considering implementing Depp lime mixing
concept form 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 improve lateraltreatment 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) with and Applications elsewhere in
Southeast Asia follow the same year. In addition, intensive trials 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, first detailed description of Lime
Column method by Arrason et al. (Linden Alimaik AB). And the first similar trial
embankrnent using Swedish Lime Column method in soft clay in Finland (6 m high, 8 mlong; 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. In addition, a Japanese paper on
Deep Lime Mixing (DLM) by Okumura and Terashi were presented to the Swedish paperon lime columns (Broms and Boman), and Japanese paper on DLM (Okumura andTerashi) presented at same conference in Bangalore, India. Both countries had proceeded
independently to this point. Limited technical exchanges occur thereafter. Following theirresearch 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 time in 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). In addition, First commercial use of 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 JapaneseConstruction 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 used commercially for first time inJapan by Seiko Kogyo Co.

15

CHAPTER 2OVERVIEW OF LIQUEFIED STABILIZED SOIL

In 1977, Cement Deep Mixing (CDM) method had been marked development. CMD
method Association established in Japan to coordinate technological development via acollaboration of industrial and research institutes and the first practical use of CMD(marine and land uses). First design handbook on lime columns (Broms and Boman)published by Swedish Geotechnical Institute. China commences research into CDM, with
first field application in Shanghai using its own land-based equipment in 1978.
The first commercial using in Japan of Dry Jet Mixing was marked in 1980, and thenit quickly superseded Deep Lime Mixing (DLM) with land-use only. In addition, DJM
Association established in Japan. After that, in 1983, Eggestad publishes state-of-the-art
report in Helsinki dealing with new stabilizing agents for Lime Column method.
In 1984, SWING method developed in Japan, followed by various related jet-assisted(W-R-J) methods in 1986, 1988, and 1991.
The Tenox Company reported more than 1000 projects completed with 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). And then,in 1990, Dr. Terashi, involved in 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 development of “secret reagents”
in Nordic Countries thereafter.
Low Displacement Jet Column Method (LDis) developed in Japan in 1991. In thesame year, Bulgarian Academy of Sciences reports results of local soil-cement researchand 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 early 1990s, First marine application of CDM at Tiajin Port, China: designed by
Japanese consultants (OCDI) and constructed by Japanese contractor with his own
equipment (Takenaka Doboku).
In 1991, Chinese Government (First Navigational Engineering Bureau of Ministry ofCommunications) builds first offshore CDM equipment “fleet”, using Japanesetechnology used for first time (1993) at Yantai Port. (Reportedly the first wholly Chinese
Design-Build DMM project.). And Jet and Churning System Management (JACSMAN)
developed by Fudo Company and Chemical Grout Company in Japan.

16

CHAPTER 2OVERVIEW OF LIQUEFIED STABILIZED SOIL

DJM Association Research Institute publishes 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 report in Japan, from1977 to 1995, more than 26 million m3 of CDM treatment reported and about 15 million
m3 of DJM treatment.
In 1997, SMW method used for massive ground treatment project at Fort Point
Channel, Boston, MA (largest DMM project to date in North America), and other adjacentprojects. Input at 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. There studies havefocused on settlement reduction from “T” shaped columns, “cross” shaped columns and“multi columns” supported embankment loading.

Figure 2.1 Flow of Liquefied soil stabilized method (Tomoharu et al., 2005)

Figure 2.2 Cement treated soil using as slope protection (Tang et al., 2001)17

CHAPTER 2OVERVIEW OF LIQUEFIED STABILIZED SOIL

Figure 2.3 Production system for foam mixed lightweight soil

Figure 2.4 Placement of cement treated soil along slope (Tang et al., 2001)

Figure 2.5 Placement of cement treated soil along slope (Tang et al., 2001)18

CHAPTER 2

2.4.

OVERVIEW OF LIQUEFIED STABILIZED SOIL

APPICATIONSIn 1997, Kuno et al. presented one of several applications of LSS method; filling acavity under pavement of urban road (Figure 2.8). The cavity is inferred mainly in theway that 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 and grown.
This application is thought to be possible of decreasing time and cost comparing to aconventional method. Thus two kinds of filed performance tests were conducted in orderto verify capability and applicability of the method and acquire necessary field data for
future maintenance works. The first field performance test used an on-site plant and astabilized soil of low strength and relatively high flow condition while the second test use
remote plant and stabilized soils of high strength and low flow condition. The tests were
evaluated in term of adequate mix proportion, working system, working time, fillingoutcome, occupation of road, result of quality control test, and so on. Through twosequential field performance tests, it is confirmed that the method possesses good
capability of filling cavities under the pavement and make it possible to decrease timeand cost.

Figure 2.6 Use of LSS for filling cavity under road surface

Murata (2011) reported that LSS consists of slurry made of on-site soil, water, cement
and sand of clay as appropriate LSS is used for backfill at upper part of a cut and covertunnel and as an invert material of a shield tunnel (Figure 2.9). Pit sand is usually used
for backfill, but LSS is much better than the sand, because it is easy to use with on-sitesoil and LSS can be buried without compaction into a narrow space. The lower part ofshield tunnel is usually buried by low-strength concrete (unconfined compressive
strength: about 10 MN/m2). From the environmental point of view, however, LSS, which
can reuse on-site soil, is now often use. Mixture of LSS was designed from the results of19

CHAPTER 2OVERVIEW OF LIQUEFIED STABILIZED SOIL

unconfined compressive tests and repeated loading tests. Then, it was designed theunconfined compressive strength of liquefied soil should be 6 MN/m2 for safety purpose.
To hold this strength level for some on-site soil, a very large amount of cement is needed(300 ~ 400 kg/m3 of LSS). So, a method to mix wasted fiber materials into LSS has beenstudied in order to increase the strength and ductility and decrease the total material cost.
Studied have been promoted on what types of wasted fiber material are available andwhat rigidity level of wasted fiber material is needed.

Figure 2.7 LSS used for backfill at upper part of cut and cover tunnel

Figure 2.8 LSS used for invert material of shield tunnel

The design of strength and quality control method of LSS used as building foundation
is proposed by Tomoharu et al. (2005). The results of the research pointed out that it isfeasible for LSS to apply for the building foundation in future perspective. Anotherapplication of LSS is for constructing fences or retaining walls. Yoshihiro et al. (2006)
reported that concrete block construction, which is common for these structures, tens tocollapse under strong earthquakes, thus causing a threat to traffic, whereas liquefied
stabilized soil block construction is capable of avoiding such damage due to the greater
toughness of the material. Also, soil blocks are advantageous over concrete blocks in term
20

CHAPTER 2OVERVIEW OF LIQUEFIED STABILIZED SOIL

of appearance. In their research, they have examined the effects of adding PVA fiber to
LSS blocks under atmospheric condition. 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 LSS block. The following Figure 2.10 is more examples of using LSS forvarious backfilling works in Japan.
Recently, most underground pipelines have been backfilled by LSS (Figure 2.10e).
Figure 2.11 shows a construction site of the pipelines using LSS. Kawabata et al. (2008)
conducted full scale field test for buried pipe using steel pipe of 3500 mm-diameter and
26 mm-thickness. Five cases of backfilling methods were applied. From the test results,

Figure 2.9 Using LSS for various backfilling works in Japanit was found that the behavior of buried pipe was strongly influenced by the stiffness of
backfilling method. In particular, the pipe which is backfilled with LSS showed stablebehavior. Moreover, Kashiwaghi et al. (2009) and Kawabata et al. (2010) have proposeda method for thrust restraint using LSS. Mode l pit experiments using a model pipe having
a diameter of 260 mm were carried out in order to examine the effectiveness of the LSS
for the thrust restraint of buried bend. LSS was applied to the passive area of the model
pipe and dry silica sand was used as backfill material. The model pipe was laterally loaded
at a speed of 1 mm/min after b ackfilling to simulate the thrust force. The lateral resistance21

CHAPTER 2OVERVIEW OF LIQUEFIED STABILIZED SOIL

and horizontal 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. Also, other experimental research results showed thatthe bending stiffness in case using LSS with geosynthetics was increased (Kawabata etal., 2009). In addition, the passive resistance was considerably increased in case using
LSS with geogrid (Kawabata et al., 2008).
In 2006, Kohata has proposed a reinforcement method for LSS by mixing crushed
newspaper as a fibered material into LSS, and carried out a series of unconfinedcompression tests and triaxial tests. The results indicated that by reinforcement effect,
brittle property of LSS mixed with fibered material after the peak was improved.
2.5.

SITUATION OF BACKFILLING PROCESS IN VIETNAM

2.5.1. Problem of backfilling method in Vietnam

Figure 2.10 Cave-in and road collapses in Hanoi city

According to report of Ministry of Construction of Vietnam, more and more cave-ins
and local subsidence have been appeared at urban areas in Hanoi city because sewer pipes
and water supply pipes were damaged. Main reason of the problems is to soil loosened
during underground infrastructure construction and water leaked from ruptured
underground pipelines. The earth under cities' roads is crisscrossed with public utility
networks supplying electricity, telecommunications services, heating and for drainage.
Large underground projects such as subways, shops and tunnels are also intensifying. The
22

CHAPTER 2OVERVIEW OF LIQUEFIED STABILIZED SOIL

roads are often dug open to install or repair various utility networks, which are managed
by different utility providers. Sometimes, the same section of a road is repeatedly dug up
and repaved by different departments. If backfilled soil has not been sufficiently
compacted, loosened soil under the road will be easily washed away by heavy rain, whichis resulting in cavities and road collapses, according to the report. Road cave-ins used tooccur only on automotive lanes, whereas in the last two years they also affected bicycle
lanes and pedestrian walks. Sewage pipes and rainwater drainage pipes usually run
underneath bicycle lanes and pedestrian walks, which are more likely to cave in after
heavy rainfall. The report suggested that if there is no other underground construction
project, usually, the road depression will not be very deep.
Therefore, the cavity under the pavement is inferred mainly in the way that thesubmerged poor backfilled material in the ground is washed out little by little to a nearby
open space, for example sewage pipe or base-floor of high-rise building underconstruction, and then, cavity is creative and grown. On the other hand, the poor
backfilled material which is insufficiently compacted causes the instability of watersupply pipe. Moreover an over compaction in the construction stage can bad impact on
the pipe structure. These are two of reasons make the main water supply pipe line of
Hanoi city easier to break (Ministry of Construction, 2014). The line was broken ten times
since operated in 2012 until 2014.
2.5.2. Inappropriate disposal of excavated soils
Nowadays, excavated soils from construction sites are becoming a serious problem in
Vietnam. It becomes more and more difficult to find reclamation sites for excavated soil
to dump around big city. Because of shortage of reclamation sites and part of soil is
disposed inappropriate, it causes the environmental pollution.

Figure 2.11 inappropriate disposal of excavated soils from construction sites in Hanoi

23

CHAPTER 2OVERVIEW OF LIQUEFIED STABILIZED SOIL

According to a new study released today by Ministry of Natural Resources andEnvironment of the Socialist Republic of Vietnam, about 1,000,000 m3 of excavated soil
will have to be trucked from construction projects to disposal sites in Hanoi city over the
next decade or two. The construction of the first phase of the metro line project alone, forexample, will generate some 1,500,000 m3 of excavated soil. The study estimates that it
could cost 100 million dollars or more to transport and dispose of these soils dependingon the future availability of sites. Another project, the City of Hanoi’s own water andsewer capital program, will produce more than 800,000 m3 between now and the end of
the decade. The question of where to put this extracted soil, according to the Ministry,some area surrounding Hanoi city are now restricting or banning the importation of soils.
2.5.3. Mining of new material from natural resources
In Vietnam, most backfilling material for construction is being extracted from natural
sources. Mining of the materials such as sand from river and gravel from mountain has asignificant impact on the natural environment. The demand for sand and gravel continues
to increase day by day. Excessive instream sand-and-gravel mining causes thedegradation of rivers. Instream mining lowers the stream bottom, which lead to bankerosion (see Figure 2.17). Depletion of sand in the streambed and along coastal areas
causes the deepening of rivers and estuaries, and the enlargement of river mouths andcoastal inlets. It may also lead to saline-water intrusion from the nearby sea. The effectof mining is compounded by the effect of sea level rise. Any volume of sand exported
from streambeds and coastal areas is a loss to the system.
Excessive instream sand mining is a threat to bridges, river banks and nearby
structures. Sand mining also affects the adjoining groundwater system and the uses that
local people make of the river.
Instream sand mining results in the destruction of aquatic and riparian habitat throughlarge changes in the channel morphology. Impacts include bed degradation, bed

Figure 2.12 Bank erosion due to depletion of sand in streambed

24

CHAPTER 2OVERVIEW OF LIQUEFIED STABILIZED SOIL

coarsening, lowered water tables near the streambed, and channel instability. Thesephysical impacts cause degradation of riparian and aquatic biota and may lead to theundermining of bridges and other structures. Continued extraction may also cause theentire streambed to degrade to the depth of excavation. Sand mining generates extra
vehicle traffic, which negatively impairs the environment. Where access roads crossriparian areas, the local environment is being impacted.
2.6.

UTILIZATION OF LSS IN VIETNAM

From the above discussion about many advantages as using of LSS for construction
works in Japan and current situation of excavating works in Vietnam, it can be said that
if LSS will be applied in Vietnam, the aforementioned serious problems can be solved.
Thus, a feasible research whether LSS can be applied in Vietnam has been carried out by
Nguyen et al., 2010. In the research, a series of physical tests for Hanoi clay (Vinh PhucClay) which was obtained from areas around the planned sites of subway at Hanoi andconsolidated-undrained triaxial compression tests (CUB tests) were performed toinvestigate strength and deformation properties of LSS using Vinh Phuc-clay as a basematerial (Vinh Phuc-clay LSS). The test results were compared with that of LSS usingbase material of NSF-clay which is common clay for LSS in Japan. The effects of crushed
waste newspaper as a fiber material into these LSS were also investigated. In addition,
the vibration characteristic of ground in the case using Vinh Phuc-clay LSS for backfillingof cut and cover tunnel was examined by two-dimensional FEM in his research. The
results of the study indicated that Vinh Phuc-clay could provide conditions satisfying LSS’
terms determined in Japanese clay, and confirmed that the LSS method is applicable inVietnam. Moreover, the strength and deformation properties of Vinh Phuc-clay LSS
mixed with fibered material has been improved. Also, the LSS shows excess
consolidation behavior caused by cementation effect, and remarkable reinforcement
effect by adding fibered material in comparison with Japanese NSF-clay LSS. In addition,
the result confirmed that the LSS has effect on reduction of ground vibration caused bytraffic load.
2.7.

SUMMARY

An overview of Liquefied Stabilizes Soil (LSS) has been presented in this chapter. In
Japan, the utilization of LSS in construction fields brings double advantages from theenvironment point of view. Thus, two big problems which are shortage of backfillingmaterial usually extracted from natural sources and excavated soil generated from25

CHAPTER 2OVERVIEW OF LIQUEFIED STABILIZED SOIL

construction sites have been effectively solved together. On the other hand, at present,
Vietnam is facing serious problems concerning the excavating works which excavatedsoil is inappropriately disposed to surrounding environment due to the shortage ofreclamation sites and the negative impacts on living environment and society as mining
sand and gravel from river and mountain to be backfilling material for construction works
and so on. In 2010, A feasible research on applicability of LSS in Vietnam has pointed
out that LSS using Vinh Phuc-clay that spread in Hanoi city of Vietnam can be
manufactured conforming to standards designated for Japanese LSS. From these, it
should be expected that LSS can be applied in Vietnam as soon as possible.
Based on the above, the aim of this dissertation is to investigate the deformation andstrength characteristics of LSS and LSS mixed with crushed waste newspaper as a fiber
material which was proposed by Kohata, 2006 and then to promote the use of LSS in
Vietnam in near future.
REFERENCES
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 andFoundation Engineering, Bangalore, Vol.1, pp. 69-75.
Terashi, M., Tanaka, H. and Okumura, T. (1979): Engineering properties of lime
treated marine 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.
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.
Suzuki, Y. (198): Deep chemical mixing methods using cement as hardening agent.
In: Symposium of Soil and Rock Improvement Technology Including Geotextile,
Reinforced Earth and Modern Piling Methods Asian Institute of Technology, Bangkok,
pp.B-1-1-B-1-24.
Bergado, D. T., Manivannan, R., Balasubramaniam, A.S., (1996): Proposed criteria
for discharge capacity of prefabricated vertical drains, Geotextiles and Geomembranes,
Vol.14, pp.481–505.
Tatsuoka, F., Kohata, Y., Uchida, K. and Imai, K. (1996): Deformation and strengthcharacteristics of cement treated soils in Trans-Tokyo Bay Highway project, In:
Proceedings of the 2nd International Conference on Ground Improvement Geosystems,
Vol.1, pp.453-459.
Uddin, K., Balasubramaniam, A.S and Bergado, D.T. (1997): Engineering behavior
26

CHAPTER 2OVERVIEW OF LIQUEFIED STABILIZED SOILof cement treated Bangkok soft clay, Geotechnical Engineering Journal, Vol.28, pp.89119.
Horpibulsuk, S., Rachan, R., Chinkulkijniwat, A., Raksachon, Y., Suddeepong, A.
(2010): Analysis of strength development in cement-stabilized silty clay frommicrostructural considerations, Construction and Building Materials, Vol.24, pp.20112021.
Chai, J.C. and Miura, N. (2005): Cement/lime mixing ground improvement for road
construction on soft ground, Ground Improvement - Case Histories, Ed. B, Indraratna,
and J.Chu, Elsevier, pp. 279-304.
Kuno, G., Okamoto, S. and Shibata, Y. (1998): Recycling excavated soil to backfilling material with liquefied stabilized soil method, Proc. CIB world building congress,
Gaevle, Sweden, 7-12 June 1998.
Kuno, G., eds (1997): Liquefied stabilized soil method-Recycling technology ofconstruction-generated soil and mud, Gihodo publication (in Japanese).
Ministry of Environment (2012): Installation of industrial waste treatment facilities,
situation on the authorization of the industrial waste treatment industry (achievements of2009), press release material (March 27th, 2012) (in Japanese)．
Japanese Geotechnical Society (2005): Committee Report Chapter 2, 2.1, 2.2 on test
methods and physical properties of cement-modified soil, Proc. of symposium, pp.2-22,
on survey, design, construction and properties evaluation methods of solidifying
stabilized soil using cement and cement-treated soil (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).
Kuno, G., Miki, H., Mori, N. and Iwabuchi, J. (1995); Study on back filling methodwith liquefied stabilized soil as to recycling excavated soils, Individual papers 20th worldroad 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 congresson environmental geotechnic, Osaka, Japan.
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.
Hino, T., Taguchi, T., Chai, J. C., and Shen, S. L. (2008): The Ariake sea coastal roadproject in the Saga lowlands: Properties of soft foundations and use of dredged clayeysoil as an embankment material, In: Proceeding of the International Symposium on
Lowland Technology, ISLT, IALT, Busan, Korea, pp.467-472.
Chai, J.C., Hino, T., Igaya, Y. and Yamauchi, Y. (2011): Embankment construction
with saturated clayey fill material using geocomposites, Geotechnical Engineering
Journal of the SEAGS & AGSSEA, Vol.42 (1), pp.35-41.
Kuno, G., Miki, H., Mori, N. and Iwabuchi, J. (1997); Filling a cavity under pavement
27

CHAPTER 2OVERVIEW OF LIQUEFIED STABILIZED SOIL

of urban road with liquefied stabilized soil, Road construction rehabilitation andmaintenance, XIII th IRF world meeting, Toronto, Canada .
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).
Murata, O. (2001): Recent research and development on soil and foundationengineering at Railway Technical Research Institute (Japan), QR of RTRS, Vol.42, No.3,
pp.122-124.
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 effectof liquefied 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 21-26, 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.1244-1254.
Nguyen, C. G. (2010): Study on advanced effective utilization of excavated soil in
Hanoi city – Vietnam, a doctoral thesis, division of civil and environmental engineering,
graduate school of Muroran Institute of technology.

28

Chapter 3

INFLUENCE OF SLURRY DENSITY ON PROPERTIES OF LSS

3.1

INTRODUCTION

In recent years, infrastructure system and many new urban areas in Hanoi city havebeen built and modernized. Urban traffic network has been invested, upgraded. Public
transportation, especially Bus Rapid Transit (BRT) and urban railway has been invested.
Vietnamese government had the plan that Hanoi’s transport plan aims to increase the shareof public transport. That is, the current low figure of 9 % trips is increased to above 60 %by 2030, by which time Hanoi city is slated to have six metro lines and three Bus Rapid
Transit (BRT) lines. However, a huge excavated soil has been generated at construction
sites which is away as waste to disposal areas being one of the challenges facing theurbanization industrialization rates in Hanoi city. Specifically, the excavated soil
generated at construction projects has been trucked to disposal sites. In addition, sandproduced from mountain or river valleys is easy to be compacted to a degree ofcompaction prescribed a standard according to conventional backfilling methods in
Vietnam. On the other hand, disposal sites in the capital city are already overloaded withthe large volume of excavated soil generated at present. This situation has caused not only
increasing the cost of the projects, but also the environmental pollution and depletion ofnatural resources.
In order to improve the situation, there is an urgent need to act strategically on recycling
excavated soil for use as backfill at the sites. In addition, recycling excavated soil plays
an important role of sustainable construction and environmental protection and this is alsoa sustainable development strategy of Hanoi city authority.
29

CHAPTER 3

INFLUENCE OF SLURRY DENSITY ON PROPERTIES OF LSS

In Japan, “Liquefied-Stabilized Soil (LSS), which is one of premixing cement treatedsoil, has recently been increasing in Japan for backfilling processes owing to its
advantages. The excavated soils discharged from construction projects can be recycled to
become backfilling material. Therefore, LSS which is one of the effective methods ofusing the construction-generated soil can solve the problem in Hanoi city at present. The
application of LSS to improve ground has successfully achieved in many construction
projects. The technology involves adding cement stabilizer to slurried soil and createstability of soil layer without compaction. In addition, the advantages of LSS have beenshown various types of excavated soils which is not necessarily good quality material tohave the appropriate fluidity by adjusting the density of soft soil with high moisture
content can be effectively used. Different LSS can be created from the slurry based
premixed stabilized soil using high-quality soil materials. However, the strength, stiffness
and brittleness of LSS increase with the increase of cement stabilizer amount.
Fiber material from crushed waste newspaper was proposed as an effective
reinforcement to improve the ductility of LSS for possessing a unique combination offiber material, cement stabilizer and excavated soil. It was found that the brittleness of
LSS mixed with fiber material after the peak in q~ε curve was improved as comparedto LSS without fiber material with proper dispersion of fiber material reinforcement.
Recently, the LSS decreased slurry density is used in order to be reduced vertical earthpressure. However, the study on strength and deformation properties of the LSS decreased
a slurry density has not been investigated.
In this study, the triaxial compressive property of LSS decreased slurry density wasinvestigated. The model ground was built with LSS mixed with fiber material amount of
0, 10 kg/m3 (Pc-0, 10), respectively into four pits in campus. In parallel, the specimens ofsame batch were also molded and cured in the laboratory. The specimens were preparedby trimming LSS retrieved from the model ground (field LSS) and cured laboratory30

CHAPTER 3

INFLUENCE OF SLURRY DENSITY ON PROPERTIES OF LSS(laboratory LSS) at the same curing time of 28 and 56 days. A series of CUB tests werecarried out under the conditions at constant strain rate of 0.054%/min and the effective
confined pressure of 98 kPa. Testing processes had been performed for two time periods
in 2016 and 2017, respectively. Based on test results, influence of slurry density on triaxial
compressive properties for LSS reinforced with fiber material was discussed.
3.2

TEST PROCEDURE

3.2.1

Test material

In this study, NSF-CLAY was used as a homogenous base material, which wascommercially available cohesive soil with very well defined the physical properties
clearly. Table 3.1 shows main physical properties of NSF-CLAY. The Geoset 200
provided by Taiheiyo Cement Co. was used as cement stabilizer. This is special cement
stabilizer for soft clay and problematic soil. Newspaper crushed like cotton by a foodprocessor was used as fiber material.
Density of particle ρs (g/cm3)

2.762

Liquid limit WL (%)

60.15

Plastic Limit Wp (%)

35.69

Plasticity Index Ip

24.46

Table 3.1 Physical Properties of NSF-CLAY

3.2.2

Mixing method

There are two LSS mixing methods to be suitable for excavated soil including the slurry
type and adjustment slurry type. For the slurry type, water is added suitably to excavatedsoil to adjust density of slurry, and then cement stabilizer is added and mixed. For
adjustment slurry type, water is added to excavated soil, then fine-grained sand or
cohesive soil is added in order to adjust density of slurry and after that cement stabilizer
is added and mixed. In this study, the LSS of slurry type was selected due to easierprocedure.
31

CHAPTER 3

INFLUENCE OF SLURRY DENSITY ON PROPERTIES OF LSSIn this study, various mixing tests have been carried out by changing slurry density andamount of cement stabilizer while investigating the bleeding rate, flow value andunconfined compressive strength of LSS at 28 curing days.
The values obtained in this way were to present a standard mix proportion for this study.
Figure 3.1 shows relation among slurry density, flow value and unconfinedcompression strength qu when the cement stabilizer of 100 kg/m3 was added in theprevious study. The bleeding rate is less than 1 %.

Based on this figure, the target slurry

density Df = 100 % was determined to be 1.280 g/cm3 with unconfined compressive
strength of 200-500 kPa and flow value of 160-300 mm. Table 3.2 shows the content offiber material, the density of slurry f, the density of LSS before mixing fiber material
LSS and the wet density of specimens t at 28 curing days. The slurry density t wascontrolled within ± 0.001 g/cm3 with target slurry density.
500

350
3

400

Unconfinedcompression
strength value

250

Flow value

350
300
250
200

200

150

160

100

150

50

Available range
100
1.16

1.18

1.20

1.22

1.24

1.26

1.28

Deviator Stress qu (kPa)

Flow (mm)450

C=100kg/m 28days● qu(kPa)■ FLOW(mm)300

1.30 3 1.32

Density of Slurry (g/m )

1.34

0
1.36

Figure 3.1 Available range of slurry density
f

LSS

t

(g/cm3)(g/cm3)(g/cm3)0 kg/m3

1.281

1.350

1.362

10 kg/m3

1.280

1.351

1.363

Content of Fiber material

Table 3.2 Result of density test32

CHAPTER 3

3.2.3

INFLUENCE OF SLURRY DENSITY ON PROPERTIES OF LSSSpecimen preparation

The purpose of this study is to determine influence of slurry density on strength anddeformation properties of liquefied stabilized soil reinforced with fiber material.
Therefore, density of slurry decided based on the standard mix proportions.
In previous studies, slurry density of 1.280 g/cm3 was used as original slurry density tocreate LSS reinforced with fiber material. The ductility of LSS improved by mixing withfiber material was confirmed through test results of a series of CUB tests.
In this study, two densities of slurry were made including 1.280 g/cm3 (Df = 100 %)and 1.216 g/cm3 (Df = 95 %). The content of cement stabilizer used in this study was 80
kg/m3 after densities of slurry reaching 1.280 g/cm3 and 1.216 g/cm3, respectively.
LSS was produced by adding and mixing cement stabilizer into slurry of LSS clay withhand mixer. In the production process, the determination of the density was performed bymeasuring the mass of slurry filled into a stainless steel mold of 400 cm3 called “AEmortar container”. After achieving the desired density, fiber material with amount of 0,
10 kg/m3 (Pc-0, 10) was added and mixed by hand mixer.

In order to determine fluidityof LSS mixed fiber material, the flow test was performed in accordance with JHS A313–
Japan Highway Public Corporation Standard. Moreover, the fresh LSS mixed with fiber
material is made to be removed the air inside specimen applying vacuum.
In this study, the fresh LSS mixed fiber material was placed into mold of 5 cm indiameter and 10 cm in height. The top surfaces of specimens were covered by a polymer
film and were cured under air humidity and temperature of 20 ± 3 oC. In parallel, the fresh
LSS was poured into four pits laid nonwoven geotextile filter, which performs thefunctions of separation and stabilization in marginal conditions of LSS shown in Figure
2. After placing, the surface of LSS was covered with a polymer sheet and cured under
outdoor condition. And then, a series of CUB tests had been carried out at 28 and 56
curing days.
33

INFLUENCE OF SLURRY DENSITY ON PROPERTIES OF LSS

D=300

L=500

L=500

CHAPTER 3

W=400

W=500

W=400

W=1300Figure 3.2 Schematic drawing of pits

3.2.4

Test method

Figure 3.3 Schematic figure of test apparatus

34

CHAPTER 3

INFLUENCE OF SLURRY DENSITY ON PROPERTIES OF LSSIn this study, a couple of Local Deformation Transducer (LDTs), which can measure
the axial deformation from small strain level without the bedding error due to thecompression of loose layers at the top and bottom ends of specimen or filter paper, were
set on the diagonally opposite surface of specimen diameter as shown in Figure 3.3. The
top and bottom ends of LDT was set between two pseudo-hinged attachments fixed on
the surface of rubber membrane at the points which were glued to the specimen to prevent
slipping between the membrane and the surface of specimen. When the value of LDT
exceeds a measurable range, the axial displacement was used the value of dial gauge bycorrecting the bedding error. In this test, a digital servo motor was used for the loading
device. This device enables to control the axial displacements with high precision, andcan ignore backlash when reversing the loading direction. The whole operation of
apparatus during test was automatically controlled by a PC software.
The CUB tests were performed for both Df = 95 % LSS and Df = 100 % LSS
specimens at curing time of 28 and 56 days. Specimens were saturated by the double
suction method which vacuum pressure was applied and the de-aired water was flowed
through specimen under a back pressure of 196 kPa.
A series of CUB tests was performed after isotropic consolidation for 12 hours underthe effective confined pressure of 98 kPa. In order to unify with previous studies, small
unloading/reloading loops during monotonic loading was applied and axial strain rate was
0.054%/min.
3.3

TEST RESULTS AND DISCUSSION

3.3.1

Relationship between deviator stress and axial strain

Figure 3.4(a)(c) show relationship between the deviator stress q (=σσ ) and theaxial strain ε in range of 03 % from CUB tests under the confining pressure σ =98kPa of both Df = 100 % LSS and 95% LSS mixed with fiber material of 0, 10 kg/m3(Pc-0, 10) at 28 curing days obtained from test results in 2016 and 2017, respectively. In
35

CHAPTER 3

INFLUENCE OF SLURRY DENSITY ON PROPERTIES OF LSS

Figure 3.4(a), although there is not noticeable difference of the maximum deviator stressbetween Pc-0 and Pc-10 in the case of Df = 100 % LSS, the deviator stress of Pc-10 is
not suddenly decreased after the peak stress state compared with Pc-0. On the other hand,the peak stresses are not clearly in both cases of Pc-0 and Pc-10 of Df = 95 % LSS. And,the maximum deviator stress, qmax of Pc-10 specimens tend to be larger than that of Pc-0
ones. Therefore, the brittle property observed in case of specimen without fiber material
has been improved by the reinforcement effect of added fiber material as similar to theprevious results. The figures show that all specimens of laboratory LSS achieve qmax at
axial strain a = 0.5 % and specimens of field LSS achieve qmax at various axial strains.
Because the temperature of field LSS during curing time could not be controlled, it may
cause effect on increasing strength of specimens. Figure 3.4(b) and (c) show the deviator
stress q (=σσ ) of field LSS specimens to be larger than laboratory LSS specimens.

In addition, qmax of LSS specimens reinforced with fiber material substantially tend to belarger than LSS specimens without fiber material and qmax of Df = 100 % tend to belarger than Df = 95 % for both laboratory LSS and field LSS. It is considered thatliquefied stabilized soil reinforced with fiber material is more advantageous thanapplication of liquefied stabilized soil in order to be constructed aseismic ground.
Figure 3.5(a)(c) show the relationship between the deviator stress q (=σσ ) and theaxial strain ε in range of 0~0.5 % for the cases of Df = 100 % and Df = 95 % mixed
with fiber material of 0, 10 kg/m3 (Pc-0, Pc=10), respectively. From the figure, ascomparing q~ε relation, although slurry density decreased 5 % from Df = 100 % toDf = 95 %, the reduction of qmax at axial strain ε = 0.5 % was about 30-35 %. However,when the qa relations are compared at same strain, the deviator stress of LSS specimen
reinforced with fiber material is larger than that of LSS specimen without it.
Figure 3.6(a) and (b) show relationship between qmax and curing days for field andlaboratory LSS mixed with fiber material amount 0, 10 kg/m3 (Pc-0, Pc-10) at 28 and 56
36

CHAPTER 3

INFLUENCE OF SLURRY DENSITY ON PROPERTIES OF LSS
300(a)
Pc-10, 100%

Deviator stress, q (kPa)250

Pc-0, 100%

200

Pc-10, 95%
150

Pc-0, 95%
100

2016, Laboratory, 28 days
Pc-0 95%
Pc-0 100%
Pc-10 95%
Pc-10 100%

50

0
0.0

0.5

1.0

1.5

2.0

2.5

3.0

Axial strain, a (%)
300

300

100%, Field

(c)

(b)
250

250

100%, Laboratory

100%, Laboratory

Deviator stress, q (kPa)

Deviator stress, q (kPa)

100%, Field
200

150

95%, Laboratory
95%, Field

100

95%, Laboratory

200

150

95%, Field
100

2017, 28 days, Pc-000.0

2017, 28 days, Pc-10

95% Field
100% Field
95% Laboratory
100% Laboratory

50

0.5

1.0

1.5

2.0

2.5

50

3.0

0
0.0

95% 28-day Field
100% 28-day Field
95% 28-day Laboratory
100% 28-day Laboratory
0.5

1.0

1.5

2.0

2.5

Axial strain, a (%)

Axial straina (%)

Figure 3.4 qεa relations up to 3 %curing days, respectively. The maximum deviator stress qmax has been obtained from
relationship between deviator stress q and axial strain a, which are results of
CUB tests under the confining pressure σ =98 kPa. Except for the qmax of field LSS, Pc10, Df = 100 %, qmax of LSS of all other cases tend to increase as increasing of curingdays. In general, qmax of cement-treated soil tend to increase during curing increases. It isconsidered that the reduction of qmax of field LSS, Pc-10, Df = 100 % was caused by theweather conditions. Because the specimens had been prepared in the beginning of winterin Hokkaido, where the temperatures sometime drop below 00C. The effects of freezing
and thawing processes of water inside the specimens under field curing condition mightlead to this issue. For this reason, it is necessary to be considered for further study.
37

3.0

CHAPTER 3

INFLUENCE OF SLURRY DENSITY ON PROPERTIES OF LSS
300

(a)

Pc-10, 100%

Deviator stress, q (kPa)

250

200

Pc-0, 100%
Pc-10, 95%

150

Pc-0, 95%
100

2016, Laboratory, 28 days
Pc-0 95%
Pc-0 100%
Pc-10 95%
Pc-10 100%

50

0
0.0

0.1

0.2

0.3

(b)

(c)

100%, Laboratory

250

200

Deviator stress,q (kPa)

250

100%, Field
95%, Field

150

95%, Laboratory100

2017, 56 days, Pc-0
95% Field
100% Field
95% Laboratory
100% Laboratory

50

0.1

0.2

0.3

0.4

0.5

100%, Field
100%, Laboratory

200

95%, Laboratory
150

100

2017, 56 days, Pc-10
5095%, Field

0
0.0

0.1

95% Field
100% Field
95% Laboratory
100% Laboratory
0.2

Axial strain, a (%)

0.3

0.4

Axial strain, a (%)

Figure 3.6 q~𝜀 relation up to 0.5 %Field LSS
350

95 %, Pc-0
300

250

56 curing days
200

28 curing days
150

30

40

50

60

Maximum deviator stress, qmax (kPa)Maximum deviator stress, qmax (kPa)350

95 %, Pc-10
300

250

56 curing days
28 curing days

200

150

30

40

350

60

56 curing days
300

250

200

28 curing days
30

40

50

60

Curing days

Maximum deviator stress, qmax (kPa)350

100 %, Pc-0

150

50

Curing days

Curing days

Maximum deviator stress, qmax (kPa)

Deviator stress,q (kPa)

0.5

300

300

0
0.0

0.4

Axial strain, a (%)

28 curing days
300

250

200

150

56 curing days

100 %, Pc-10
30

40

Curing days

Figure 3.6(a) qmaxcuring days relation for Field LSS

38

50

60

0.5

CHAPTER 3

INFLUENCE OF SLURRY DENSITY ON PROPERTIES OF LSS

Laboratory LSS
350

95% Pc-0

Maximum deviator stress, qmax (kPa)Maximum deviator stress, qmax (kPa)

350

300

250

56 curing days
200

150

28 curing days

30

40

50

60

100% Pc-0
56 curing days

300

250

200

150

28 curing days

30

40

Curing days
350

95% Pc-10

Maximum deviator stress, qmax (kPa)Maximum deviator stress, qmax (kPa)

350

300

250

56 curing days
200

28 curing days
150

30

40

50

60

Curing days

50

60

100% Pc-10

56 curing days

300

250

28 curing days

200

150

Curing days

30

40

50

60

Curing days

Figure 3.6(b) qmaxcuring days relation for Laboratory LSS

3.3.2

Deformation property

Deviator stress, q (kPa)a) Definition of Young’s modulus

Etan

1

E0
1
Eeq
1

E0: Initial Young’s modulus
Etan: Tangent Young’s modulus
Eeq: Equivalent Young’s modulus

Axial strain，𝜀 %Figure 3.7. Definition of various Young’s moduli

Figure 3.8 shows the definitions of various Young’s moduli. The initial Young’s
modulus E0 is defined as initial stiffness at ε =0.002 % or less. The tangent Young’s
modulus Etan is defined as tangential gradient in q~ε curve, it indicates the non-linearity
39

CHAPTER 3

INFLUENCE OF SLURRY DENSITY ON PROPERTIES OF LSS

of deformation property in q~ ε

relation. The equivalent Young’s modulus Eeq isobtained from small unloading/reloading loop during monotonic loading. The Eeq
indicates a changing degree of damage under the shearing.
b) Tangent Young’s modulus Etan
Figure 8(a) and (b) show the influence of curing days on Initial Young’s modulus E0
of Df = 100 % and Df = 95 % cured field and laboratory conditions, respectively. It isfound from Figure 8(a) and (b) that the values of E0 increase as the increasing of curingdays except for that of E0 for LSS specimen of Pc-10, Df = 100 %. In case of LSS
specimen of Pc-10, Df = 100 %, the value of E0 decreases at 56 days. It is considered tohave become in the beginning of winter. It might cause reduction of E0 undercuring field condition. The effect of curing temperature on E0 is also consistent
with previous study. In present study, the temperature inside the ground
during curing in the field has not been measured. Therefore, investigation ofeffect of temperature on E0 of LSS need to be considered for further study.
Figure 8(b) show that E0 of Pc-0 LSS are larger than E0 of Pc-0 LSS and E0 of
Df = 100 % larger than Df = 95 %.
Figure 9(a)(e) show relationship between Etan/E0 and q/qmax of Pc-0, Pc-10 for Df=
100 %, Df= 95 %, respectively. The results have been obtained from the analysis of qacurve of CUB tests under the confining pressure of 98 kPa. The figures show that
reduction rate of Df= 95 % is larger than that of Df= 100 %. Therefore, it seems thatthe nonlinearity increases as decreasing of slurry density. On the other hand, cementtreated soil has been reported that nonlinearity of stress-strain curve decreases as curing
increases. In the results of this study, the nonlinearities of 28 and 56 days tend to be similar.
It is considered that the curing days of 56 days were short in order to investigate the effectof curing days on nonlinearity.

40

CHAPTER 3

INFLUENCE OF SLURRY DENSITY ON PROPERTIES OF LSS

Field LSS
700

700

600

600

500

28 curing days

500

E0

E0

28 curing days
400

400

300

300

56 curing days

200

56 curing days

Pc-0 100%

Pc-0 95%
30

40

50

200

60

30

40

Curing days

50

60

50

60

Curing days

700

700

600

28 curing days

600

28 curing days
E0

500

E0

500

56 curing days
400

400

300

56 curing days300

Pc-10 95%
200

Pc-10 100%

30

40

50

200

60

30

40

Curing days

Curing days

Figure 3.8(a) E0curing days relations for Field LSS

Laboratory LSS
700

Pc-0 95%

700

600

Pc-0 100%600

56 curing daysE0

E0

56 curing days
500

500

28 curing days
400

400

28 curing days
300

30

40

50

300

60

30

40

Curing days

700

50

60

Curing days

Pc-10 95%

700

600

Pc-10 100%

56 curing days

600

E0

E0

56 curing days
500

500

28 curing days
400

400

28 curing days
300

30

40

50

300

60

Curing days

30

40

50

Curing days

Figure 3.8(a) E0curing days relations for Field LSS

4160

CHAPTER 3

INFLUENCE OF SLURRY DENSITY ON PROPERTIES OF LSSc) Equivalent Young’s modulus, Eeq
Figure 10(a)(e) and relationship between Eeq/E0 and q/qmax of both Pc-0, Pc-10 forDf= 100 %, Df= 95 %, respectively. The values of Eeq were obtained from the q~εcurve of the CUB tests under the confining pressure of 98 kPa at small loading/unloading
loop during monotonic loading.

1.0

2016, 28 days, Laboratory
Pc-0 95%
Pc-0 100%
Pc-10 95%
Pc-10 100%0.8

Etan/E0

0.6

0.4

0.2

(a)

0.0
0.0

0.2

0.4

0.6

0.8

1.0

q/qmax1.0

95% Field
100% Field
95% Laboratory
100% Laboratory

0.8

0.6

2017, 28 days, Pc-10
95% Field
100% Field
95% Laboratory
100% Laboratory

0.8

0.6

Etan/E0

Etan/E0

1.0

2017, 28 days, Pc-0

0.4

0.2

0.2

(b)
0.0
0.0

0.4

0.2

0.4

0.6

0.8

(c)

0.0
0.0

1.0

0.2

0.4

q/qmax1.0

1.0

2017, 56 days, Pc-0
95% Field
100% Field
95% Laboratory
100% Laboratory

0.8

0.6

0.8

1.0

2017, 56 days, Pc-10
95% Field
100% Field
95% Laboratory
100% Laboratory

0.8

0.6

Etan/E0

Etan/E0

0.6

q/qmax

0.4

0.2

0.4

0.2

(e)

(d)

0.0
0.0

0.2

0.4

0.6

0.8

0.0
0.0

1.0

0.2

q/qmax0.4

0.6

q/qmaxFigure 3.9 Etan/E0q/qmax relations

42

0.8

1.0

CHAPTER 3

INFLUENCE OF SLURRY DENSITY ON PROPERTIES OF LSS

In general, it has been reported that initial Young’s modulus E0 of cement-treated soil
at small strain is independent of the confining pressure, thus, the Eeq/E0 is considered toindicate the change degree of damage during shear. At the initial portion of shear, the soil
specimen shows local failure, and finally, the soil specimen is collapsed as the shear bandis formed. This behavior can be explained considering that cementation is broken
therefore soil fabric changes and in consequence elastic properties change.
There is no significant difference in reduction rate of Eeq/E0 of Pc-0 and Pc-10 in Df= 100 % and Df = 95 % except Pc-0 at 28 curing days for both field and laboratory.
However, it is seen from these figures that the reduction rate of Eeq/E0 of Pc-10, Df =100 % tends to be slightly smaller than that of Pc-0, Df = 95 %. Thus, Pc-10, Df =100 % will cause the reduction of the local damage during shear.
It is seen from Figure 10 (a) that the reduction rate of Eeq/E0 of Df = 95 % tends to belarger than that of Df = 100 % as comparing reduction rate Eeq/E0 between Df = 100 %and Df = 95 % at 28 curing days cured laboratory. Therefore, the reduction of slurry
density is suggested to be increased the local damage during shear.
As shown in Figure 10(a)(d), the significant tendency is not seen. That is, a scatteringof Eeq/E0q/qmax relations are large. It is considered that damage are caused due to a cured
condition in field, an influence of disturbance during sampling and during setting a
specimen on an apparatus and so on.
Then, in the judging from the overall point of view, it is considered that the specimen
prepared on the reduction of slurry density is easily damaged.
1.0

1.0

0.9
0.8

0.9

(a)

(b)

0.8

Eeq/E0

Eeq/E0

0.7
0.6
0.5
0.4
0.3
0.0

2016, 28 days, Laboratory
Pc-0 95%
Pc-0 100%
Pc-10 95%
Pc-10 100%
0.2

0.7
0.6
0.5
0.4

0.4

0.6

q/qmax

0.8

1.0

43

0.0

2017, 28 days, Pc-0
95% Field
100% Field
95% Laboratory
100% Laboratory
0.2

0.4

0.6

q/qmax0.8

1.0CHAPTER 3

INFLUENCE OF SLURRY DENSITY ON PROPERTIES OF LSS

1.0

1.0

0.9
0.8

0.8

0.6

Eeq/E0

Eeq/E0

0.7
0.6
0.5

2017, 28 days, Pc-10

0.4
0.3
0.2
0.0

0.2

0.4

2017, 56 days, Pc-0

0.4

95% Field
100% Field
95% Laboratory
100% Laboratory

0.2

(c)
0.6

95% Field
100% Field
95% Laboratory
100% Laboratory

0.8

1.0

0.0

0.2

q/qmax

0.4

(d)
0.6

0.8

1.0

q/qmax

1.0
0.9
0.8

(e)

Eeq/E0

0.7
0.6
0.5

2017, 56 days, Pc-10

0.4
0.3
0.2
0.0

95% Field
100% Field
95% Laboratory
100% Laboratory
0.2

0.4

0.6

0.8

1.0

q/qmaxFigure 3.10 Eeq/E0~q/qmax relations

3.4

CONCLUSIONS

The following conclusions were derived based on test results.
1. When the slurry density is slightly decreased from the appropriate slurry density
obtained from the standard mix proportion design figure, it is considered that the
qmax decreased remarkably. In addition, it is found that the local damage caused byshearing even in the case of low slurry density is reduced by the effect ofreinforcement on the fiber material.
2. The Etan/E0 ~ q/qmax relation of both LSS cured in laboratory and at field shows
relatively similar tendency. In addition, it seems that the nonlinearity of q~ε
relation increase as decreasing slurry density.
3. The influence of slurry density on the degree of damage caused by shear is large
and it seems that the degree of damage tends to be reduced by the addition of fiber
material.
44

CHAPTER 3

INFLUENCE OF SLURRY DENSITY ON PROPERTIES OF LSSREFERENCES
1) Kuno, G., eds (1997): Liquefied stabilized soil method-Recycling technology ofconstruction-generated soil and mud, Gihodo publication (in Japanese).
2) Japanese Geotechnical Society (2005): Committee Report Chapter 2, 2.1, 2.2 on test

methods and physical properties of cement-modified soil, Proc. of symposium, pp.222, on survey, design, construction and properties evaluation methods of solidifying
stabilized soil using cement and cement-treated soil (in Japanese).
3) 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).
4) Kohata, Y., Ichikawa, M., Nguyen, C. Giang., and Kato, Y. (2007): Study of damage
characteristics of liquefied stabilized soil mixed with fibered material due to triaxial
shearing, Geosynthetics Engineering Journal, Vol.22, pp.55-62 (in Japanese).
5) Ito, K., Kohata, Y., and Koyama, Y. (2011): Influence of additive amount of cement
solidification agent on mechanical characteristics of Liquefied Stabilized Soil mixed
with fibered material, Japanese Geotechnical Society Hokkaido Branch Technical
Report Papers, Vol.51, pp.131-136 (in Japanese).
6) Duong, Q. Hung., Kohata, Y., Omura, S., and Ozaki, K. (2014): Strength anddeformation characteristics of liquefied stabilized soil reinforced by fiber material
prepared at laboratory and field, Geosynthetics Engineering Journal, Vol.29, pp.33-40.
7) 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.
8) Kohata, Y., Tatsuoka, F., Wang, L., Jiang, L. G., Hoque, E., and Kodaka, T. (1997):
Modelling the non-linear deformation properties of stiff geomaterials, Géotechnique,Vol.47, No.3, pp.563-580.
9) Kohata, Y., Jiang, L. G., Murata, O., and Tatsuoka, F. (1999): Elastic-properties-basedmodelling of non-linear deformation characteristics of gravels, Proc. of the second
Inter. Symposium on Pre-Failure Deformation Characteristics of Geomaterials-IS
Torino 99, pp.533-539.

45

Chapter 4

METHODS FOR DETERMINING DYNAMIC
PARAMETERS OF SOIL

4.1

INTRODUCTION
The response of soil to cyclic loading is controlled mostly by mechanical properties

of soil. There are several types of geotechnical engineering problems associated withdynamic loading such as wave propagation, machine vibrations, seismic loading,liquefaction and cyclic transient loading, etc. The mechanical properties associated withdynamic loading are shear wave velocity (Vs), shear modulus (G), damping ratio (D), andPoisson’s ratio (n). The customary name for this type of properties is “dynamic soil
properties”, even though they are also used in many non-dynamic type problems. The
engineering problems governed by wave propagation effects induce low levels of strain
in the soil mass. On the other hand, when soils are subjected to dynamic loading that may
cause a stability problem then, large strains are induced.
The selection of the appropriate testing method used for engineering problems needs
careful consideration and understanding of the associated level of strain. There are avariety of laboratory and field methods that measure the low- and high-strain soil behavior.
This paper addresses the methods that are based on geophysics that for the most partencompass the low-strain properties or wave propagation type problems.
4.2

UTILITY OF MEASURED PARAMETER
1) Shear wave velocity (Vs)
Shear wave velocity (Vs) is the most commonly used measured parameter used inshallow soil geophysics for soil characterization. It is used to calculate the following
parameters in the elastic range of soil behavior. The importance in its utility is that theparticle of motion travels perpendicular to the direction of wave propagation being able
to measure the shear properties of the soil skeleton and not the fluids that cannot takeshear.
46

CHAPTER 4

METHODS FOR DETERMINING DYNAMIC PARAMETERS OF SOIL

2) Shear modulus (G)Shear Modulus (G) is a calculated parameter based on the Vs using the simple elastic
relationship Gmax = × Vs2. The mass density is often estimated or measured by a nearby
subsurface sampling or using correlations. Advanced correlations to estimate the value ofthe dynamic shear modulus are available based on the standard penetration test, Atterberg
Limits (plasticity index) and grain size distributions (Vucetic and Dobry, 1991, Idriss, etal., 1980). The shear modulus is used to perform more advanced soil modeling, anddynamic response of the soil-structure interactions. Shear modulus at lowstrain levels as
measured by geophysical techniques will provide the elastic parameter for machinefoundation analysis or earthquake engineering. The important utility of this parameter isthat it can be used as a varying parameter with respect to strain making the soil response
represent the real modulus degradation in soil behavior. This parameter is used in defining
the stiffness matrices for finite element analysis of earth structures and foundation soils.
3) Maximum Shear Modulus (Gmax)
Maximum Shear Modulus (Gmax) is used to normalize the shear modulus (G) vs. shear
strain relationships. These normalized relationships allow the engineer to use wellestablished degradation curves and scale them to the measured in-situ value of Gmax. For
example, the classic relationships of the shear moduli for cohesionless and cohesive soils
are provided in Seed, et al., (1984) and Sun, et al., (1988). In the absence of extensive
dynamic soil testing at all ranges of shear strain these curves are used and Gmax is usedas the scaling parameter.
4) Damping Ratio (h)Damping Ratio (h) is used in several dynamic analysis procedures to provide a realistic
motion attenuation. This ratio is based on the material damping properties. The damping
ratio vs. shear strain relationships for cohesionless and cohesive soils are provided in Seed,et al., (1984) and Sun, et al., (1988). Since damping ratio is also shear strain dependent,
it is required to have several values with strain. Dynamic analysis results are also
influenced by the damping ratio for single and multi-degree modal systems. The effects
of soil-structure interaction also influence the damping of the system making it an area
where recent research has focused. The utility of this parameter is based on the ability ofthe system to absorb dynamic energy and how this will affect the duration and modes ofvibration.
47

CHAPTER 4

METHODS FOR DETERMINING DYNAMIC PARAMETERS OF SOIL

5) Poisson’s Ratio (n)Poisson’s Ratio (n) is a fundamental parameter that is difficult to measure and it is usuallyestimated in engineering calculations. The ratio of horizontal to vertical strain is required
to relate moduli and strains in a solid body. A suggested range of values for Poisson's ratio
for soils is from 0.2 to 0.5, less common values may be as low as 0.1 for loess deposits.
This ratio can be calculated [n = E/(2G-1)] based on laboratory tests at low strains if G
and E are obtained from torsional and longitudinal vibration, respectively.
4.3

GEOTECHNICAL APPROACHES TO DETERMINE DYNAMIC SOILSPROPERTIES
Geophysical methods have been used for many years by engineers in soils andfoundation applications. Geophysics not only provides means to probe the properties ofsoils, sediments and rock outcrops, but are also used to determine dynamic properties ofsoils, particularly the soil’s compression and shear wave velocities, as well as the soil’s
elastic and shear moduli. These properties are key parameters in predicting the responseof soils and soil-structure systems to dynamic loading. The geophysical methods used indetermining dynamic properties of soils are mainly field or in-situ tests based on
measurement of velocities of waves propagating through the soil. The most common tests
used for such purposes are presented subsequently.
1) Seismic Refraction
The seismic refraction method is well suited for general site investigations for soil
dynamics and earthquake engineering purposes. This technique provides for thedetermination of elastic wave velocities of a layered soil profile. Wave velocities andthickness of each layer are determined as long as the wave velocities increase with eachsuccessively deeper layer. The test aims to accurately measure the arrival-times of theseismic body waves, which consists of Compression P- and shear S- waves, produced bya near-surface seismic source. The source travels through the soil to a linear array ofdetectors placed at the ground surface. Compression P-waves arrive at a receiver fasterthan shear S-waves, thus obscuring the arrival of the latter waves i.e. the S-waves.
The parameters relate to compression wave velocity (vp) and shear wave velocity (vs)of soil, G, E, ν, by the following equations (Das, 1995; Kramer, 1996; Verruijt, 1994):
Shear modulus:48

CHAPTER 4GMETHODS FOR DETERMINING DYNAMIC PARAMETERS OF SOIL

ρ. 𝜈

(4.1)

Elastic modulus:
E

.

(4.2)

Poison’s ratio:
ν

(4.3)

Figure 4.1 Field and laboratory methods for determining dynamic parameters

The parameters can be determined by field and laboratory method presented inavailable literatures (Das, 1995; Kramer, 1996; Karl, 2005; Schneider et al., 1999). A
representation of these test procedures is shown in Figure 4.1.
Advantages and disadvantages
The seismic refraction test is a popular test because of its simplicity and because of
the low costs involved. It is a non-invasive test, meaning that no boreholes or cone
penetrations are necessary. This is a significant benefit of the test since boreholes are
expensive and cone penetration tests may have difficulties penetrating hard layers.
However, there are some disadvantages to the seismic refraction test. Firstly, the test
assumes that the P-wave velocity increases monotonically with depth. Layers that aresofter than the layer above cannot be detected with the seismic refraction test. When theunderlying layer is softer, wave paths will become more vertical and therefore no49

CHAPTER 4

METHODS FOR DETERMINING DYNAMIC PARAMETERS OF SOIL

critically refracted wave can exist. Not only will the soft layer be impossible to detect, it
will also make the underlying layers seem deeper than is effectively the case. Secondly,
the assumed horizontality of the layers can lead to wrong estimations of the P-wave
velocities when the layers are actually inclined, as the assumed wave path is not valid forinclined layers. This problem is overcome by measuring the arrival times in two directions
from the source. Finally, one should be aware that “blind spots” can be caused by layersthat are too thin or layers that have a too low impedance contrast with the overlying layer.
An important advantage of the seismic refraction test is that it can be combined with The
Spectral Analysis of Surface Waves test. Both tests use the same test set-up andmeasurement data. They differ only in the postprocessing of these data. Combining the
postprocessing of the two tests has some important synergies.
2) Cross-Hole Technique
The cross-hole method uses two or more boreholes, with an excitation source in one
borehole and receivers in the others. Using more than two boreholes makes the method
more reliable and makes the method useable for material damping estimations.
Test procedure
The method starts with the drilling of the required number of boreholes. In soft soils,
the boreholes typically need a lining, preferably made of plastic tubing. There are two
ways of performing the cross-hole method. The first method starts with the drilling of thecomplete boreholes. After the drilling of the boreholes, the source and receivers are
installed at a certain depth and stepwise lowered into the hole. In the second method, thedrilling is also done stepwise. After each drilling step, the source and receiver are installedat the bottom of the borehole and the experiment is executed. As for the up-hole method,
one can use a falling weight or a rotary source as excitation. For the cross-hole test, therotary source can be used to create horizontally polarized shear waves and the fallingweight can be used to create vertically polarized shear waves. The combination of both
can identify an anisotropic soil model, with a different vertical and horizontal shear wave
velocity. An explosive source can be used to generate dilatational waves. High frequency
signals are preferred, so that near field effects are avoided.
The other boreholes are used for the installation of vibration receivers, for which
geophones or accelerometers may be used. The receivers are lowered to the same depth
as the excitation source, which means that horizontally traveling waves are measured. To
50CHAPTER 4

METHODS FOR DETERMINING DYNAMIC PARAMETERS OF SOIL

ensure a good coupling between soil and receiver, a backfill material may be needed. This
is not needed if the drilling is also done stepwise. When all receivers and the excitation
source are installed at the same depth, the experiment can start. The excitation source isactivated, triggering the data acquisition and the ground motions are recorded in each of
the receiving boreholes. This process is repeated until a sufficiently high SNR is obtainedby stacking the time signals. The averaged time signals are used for the determination of
the arrival time and the motion intensity. The latter is needed for the estimation of thematerial damping ratio. The source and receiver are then lowered further in the borehole.
Typical step lengths are between 0.5 and 1m. When measurements are done to depths
over 20m, it might be necessary to measure the inclination of the holes. This inclination
has an effect on the distance between boreholes, which becomes significant for large
depths. If the inclination is measured, the cross-hole method can be used up to depths of
50 to 80m.
Advantages and disadvantages
Because multiple boreholes are needed, the method is very expensive. However,results for the wave velocities are of good to very good quality. One has to be aware of
the risk that refracted waves, traveling through nearby stiffer layers, may arrive before
the direct horizontal wave. This risk increases when layers are thin and when the receiving
boreholes are further from the transmitting borehole. This makes the spacing between theboreholes a crucial test parameter. The numerical accuracy increases when the boreholes
are well separated, but a large distance between the boreholes increases the likelihoodthat refracted waves arrive before the the direct waves. A disadvantage of the method isthe assumption of horizontal layers. When this assumption does not hold, the results will
be incorrect. Another disadvantage is the difficulty of estimating the damping properties.
To obtain a reasonable accuracy, the receivers need to be clamped to the borehole wallvery well.
3) Down-Hole Techniques
Seismic down-hole tests measure the shear and dilatational wave velocities by placing
vibration receivers in a borehole and measuring the arrival times of both types of waves.
Test procedure

51

CHAPTER 4

METHODS FOR DETERMINING DYNAMIC PARAMETERS OF SOIL

Figure 4.3 shows a schematic of the test setup. The test starts with the drilling of aborehole and the installation of a vibration source next to it. A vibration receiver is thenclamped to the borehole wall at a certain depth z1. This receiver may be a geophone oran accelerometer. Next, the excitation source is used to generate dilatational and shear
waves, of which the arrival is detected by the receiver in the borehole. Pressure sensors
are installed at the source, to serve as a trigger for the start of the measurements. To reduce
the uncertainty due to noise, the test is repeated a number of times. The results of all tests
are stacked to obtain a higher signal to noise ratios. The receiver is then lowered into theborehole, with steps ∆z that are typically between 0.5 and 1 m. The test is repeated forevery receiver depth zi. If enough sensors are available, then an alternative to thisstepwise procedure is to install a series of sensors simultaneously in the borehole. This
procedure allows for a faster execution of the down-hole test.

Figure 4.2 Cross-hole method

Advantages and disadvantages

52

CHAPTER 4

METHODS FOR DETERMINING DYNAMIC PARAMETERS OF SOIL

The advantage of the down-hole method is that it provides fairly accurate results, witha high spatial resolution. The disadvantage over the Seismic Cone Penetration Test
method is the elevated cost of the method.

Figure 4.3 Down-hole method

4) Up-Hole Techniques
Seismic up-hole tests measure the shear and dilatational wave velocities by placing an
excitation source in a borehole and measuring the arrival times of both types of waves atthe surface.
Test procedure
The up-hole test is very similar to the down-hole test. Figure 4.4 shows the test setup.
The excitation source is now located in the borehole and the vibrations are recorded at
the surface. The test thus starts with the drilling of a borehole and the installation of avibration receiver, a geophone or an accelerometer, next to it. An excitation source is thenlowered into the borehole. The possibilities for the excitation source are limited due to53

CHAPTER 4

METHODS FOR DETERMINING DYNAMIC PARAMETERS OF SOIL

the fact that it has to be useable in a confined space. To generate P-waves, a vertical source
needs to be used, this can for example be a falling weight. To generate S-waves, a rotarysource may be used. As for the down-hole method, the test is repeated a number of times
for every excitation depth. The different data records are then stacked to obtain a higher
signal to noise ratios.
Advantages and disadvantages
The advantage of the up-hole method is that it provides fairly accurate results, with ahigh spatial resolution. The disadvantage over the SCPT method is the elevated cost of
the method.

Figure 4.4 Up-hole method

5) Steady-State Surface Wave Technique:
The steady state surface wave technique does not require boreholes and is another insitu method used to measure the shear modulus (G) of all types of soils. In this test, anelectromagnetic oscillator at high frequency (30 to 1000 cycles/second, cps) or a rotating
mass type oscillator to produce low frequency vibrations (less than 30 cps) are used.
These surface vibrators generate Rayleigh R-waves, which at low strains have nearly thesame velocity as the shear waves. The ground surface can be deformed as shown in Figure4.5. The shear wave velocity is computed from the Rayleigh wave-length measured withreceivers placed along the ground surface.
54

CHAPTER 4

METHODS FOR DETERMINING DYNAMIC PARAMETERS OF SOIL

6) Spectral Analysis of Surface Waves (SASW):
The Spectral Analysis of Surface Waves (SASW) test is a non-invasive test method todetermine the dynamic shear modulus and the material damping ratio of shallow soil
layers. The SASW method has been used to investigate pavement systems, to assess thequality of ground improvement, to determine the thickness of waste deposits, and to
identify the dynamic soil properties for the prediction of ground vibrations.

Figure 4.5

Steady-State Surface Wave Test

Physical principle
The method relies on the measurement of surface waves. Surface waves propagate in
the horizontal direction and decay exponentially with depth. For low frequencies, thewavelength of the surface waves is large and the surface waves reach deep soil layers.
These layers are generally stiff and weakly damped, resulting in a high phase velocity anda low attenuation coefficient. For high frequencies, the wavelength of the surface waves
is smaller and the surface waves travel through shallow soil layers. These layers are
generally softer and more strongly damped, resulting in a lower phase velocity and ahigher attenuation coefficient. As a consequence, the phase velocity and attenuation
coefficient of surface waves vary with the frequency and are determined by the variationof the soil properties with depth.
Advantages and disadvantages
As the SASW method is based on a non-invasive test, it is an inexpensive method
since it does not require the use of cone penetration or boreholes. The test can also be
executed relatively quickly. It is also an advantage that the test can lead to estimations ofboth the shear wave velocity and the material damping ratio. On the other hand, theresolution of the test is limited in terms of depth and spatial scale: it is difficult to identify
55

CHAPTER 4

METHODS FOR DETERMINING DYNAMIC PARAMETERS OF SOIL

the properties of deep layers (more than 10-15 m) and to detect thin layers. This may not
be an issue, as deep and thin layers may also have little impact in ground vibration
predictions, depending on the frequency range of interest. Furthermore, the depth problem
can be overcome by the use of a passive SASW. The experimental setup of the SASW
method is the same as for the seismic refraction test, which means that the data collectedfrom an SASW test allow for the simultaneous determination of the dilatational wave
velocity. Combining both inversion analyses into one, gives important synergies. In every
iteration step, one soil profile is generated, which is used to compute the theoreticaldispersion curve and surface response. The first is compared with the experimental curvefrom the SASW method and the latter is compared to experimental surface response data.
A combined residual is now minimized. In this technique, the layer interfaces for the Pand Swave velocity will match. Furthermore, one can use information from the S-wave
velocity profile to make assumptions about possible inverted P-wave velocity profiles.
This would increase the reliability of the P-wave velocity estimations.
7) Seismic Cone Penetration Test (SCPT)The SCPT has been more recently developed (Campanella and Robertson 1984). The
test combines the seismic downhole technique with the standard Cone Penetration test. A
seismic pick-up or receiver is added to the cone, then the similar procedure as the one
followed with the seismic downhole test is used. At the surface, a shear force is induced
while the penetration is paused momentarily In order to compare the intensity of signals
arriving at the receiver at various depths, a source that is capable of generating repeatablesignals is used. This is insured by the use of a single hammer weight and height of fall(Campanella and Davies, 1994). Typical test set up of the SCPT is presented as Figure 6.
The shear wave velocity, VS, is calculated by dividing the difference in travel path
between two depths by the time difference between the two signals recorded. Advantagesof the SCPT in comparison with other conventional seismic in-situ tests, reside in its
speed, the fact that it also provides static soil properties such as point bearing (qc) andsleeve frictional resistance (fs ) as well as ground proofing and stratigraphy of the site.
The strain induced immediately around the probe during penetration is a very large strain
and thus, both large and small strain parameters can be obtained. In addition the SCPT
can be considerably less expensive than other conventional seismic techniques.
Advantages and disadvantages
56

CHAPTER 4

METHODS FOR DETERMINING DYNAMIC PARAMETERS OF SOIL

This technique has the advantage that a high resolution can be obtained. Anotheradvantage is that it does not require a borehole, nor the difficulties associated with placing
sensors in a borehole. However, being an invasive method, the cone might be unable topenetrate hard layers, placing a potentially unacceptable limit on the measurement depth.

Figure 4.6 Seismic Cone Penetration Test

8) Suspension PS logging
The suspension PS logging is a recently developed tool for measurement of seismic
wave velocity profiles. A seismic source and two receivers are built in a single boreholeprobe. Compression (P) and shear (S) waves are generated by a seismic source thatinvolves the use of a solenoid hammer. The solenoid hammer produces a pressure wave
in the borehole fluid. This pressure wave converts into seismic body waves (P and S) at
the borehole wall. The waves travel in a radial direction from the borehole wall. Receivers
contain two-component geophones, one vertical to record P-waves, and one horizontal
for recording of S-waves. The body waves are converted back to pressure waves in theborehole fluid and detected by the geophones. The source and the two receivers areconnected with rubber-filter tubes to isolate vibration between them. The Spacing
between two receivers is usually one (1) meter (Nigbor and Imai, 1994). Figure 8 showsa schematic of the test field setup.

57

CHAPTER 4

METHODS FOR DETERMINING DYNAMIC PARAMETERS OF SOIL

Advantages and disadvantages
The major advantage of the method is the depth to which it can be used, maximum
depths up to 700 m have been reported. The test duration depends on the desired spatial
resolution. The conventional test is executed by lowering the probe one meter at a time.
In this case, there is no overlapping of the soil intervals for which average velocities aremeasured and one can approximately measure 100 soil intervals in 2.5 hours. If theresolution is increased, by using a step of half a meter, the test time is almost doubled. In
some tests, and for certain depth intervals, intervals of 0.2 m have been used. In bothFigure 4.7 - Suspension PS Logging test

cases a SIRT (Simultaneous Iterative Reconstruction Technique) analysis routine can beused to perform a least-squares inversion of the overlapping average velocities at each
one meter depth interval.
From the analysis of methods determining the ground dynamic parameters, theprocedures should be met the following requirements:- Requirements of equipment and facilities for the tests- Requirement of professional skill of engineer- Requirement of experience of engineer
From the current situation of Vietnam, it is realized that:- Due to the financial difficulties, almost project consider only in static problem
without using the dynamic parameters

58

CHAPTER 4

METHODS FOR DETERMINING DYNAMIC PARAMETERS OF SOIL

- From the point of view of commercial efficiency, expenses for investment of the
dynamic tests is very expensive, so hardly laboratory can equip if they have nofinancial support from non-profit organization. For example, University ofTransport Technology, Hanoi, Vietnam has been supported the finance of 6.5
million dollars by Japan International co-operation Agency (JICA) to invest theequipment for their laboratory but it has no apparatus for determining the dynamic
parameters of soil specimen.
- In Vietnam, The standard of geotechnical investigation is for calculation and designof the static problems. Moreover the testing standards for the dynamic problems
with fully legal corridor have not been promulgated to promote this field unless the
special projects or works must refer to other standards from foreign country.
Therefore, it is necessary to select a suitable method for estimating the ground
dynamic parameters in Vietnam. The objective of this chapter is to establish a procedure
based on the methods of previous researches in the world for estimating the ground
dynamic parameters which is suitable for current condition of Vietnam.
Recently, Andrus et al. (2003) have developed the procedures for estimating dynamic
properties of soils in South Carolina of America. When site-specific shear wave velocity,
vs, are not available or need to be supplemented, an estimation of the shear wave velocity,
vs, can be made by the use of correlations with in-situ testing such as the Standard
Penetration Test (SPT) or the Core Penetration Test (CPT). The procedures for correlating
SPT and CPT results with shear wave velocity, vs, have been summarized in design
standard, Geotechnical Earthquake Engineering, South Carolina Department ofTransportation (2008).
The unified formulas which express the dynamic shear moduli and the damping ratios
in terms of maximum dynamic shear modulus, cyclic shear strain amplitude, meaneffective confining pressure and soil’s plasticity index have been proposed by Ishibashi,Zhang (1993). The formulas fitted experiment data reasonably well and could be
conveniently utilized in dynamic analyses such as seismic ground respond and soilstructure interaction problems. The formulas cover wide variety of soils ranging fromsands to highly plastic clays.
4.4

ESTIMATION OF DYNAMIC SOIL PROPERTIES

4.4.1

Estimation of shear wave velocity, vs, from SPT data59

CHAPTER 4

METHODS FOR DETERMINING DYNAMIC PARAMETERS OF SOIL

Recommended equations to estimate shear wave velocity, vs, are based onstandardized SPT blow count (N*60), depth (Z), Fines Content (FC), geologic age andlocation of deposit, and Age Scaling Factor (ASF). Equations for estimating shear wave
velocity, vs, are provided in Table 4.1.
Table 4.1 SPT (N*60) – Shear Wave Velocity, vs, Equation for Sand
(Andrus et al., 2003)

Fines Content, FC

Equation for predicting vs (m/s)

Equation No

< 40%

𝑣

72.9 𝑁 ∗

.

𝑍 .

𝐴𝑆𝐹

4.4

10% to 35%𝑣

72.3 𝑁 ∗

.

𝑍 .

𝐴𝑆𝐹

4.5

<10%

𝑣

66.7 𝑁 ∗

.

𝑍 .

𝐴𝑆𝐹

4.6

N*60=blows/0.3m and Z=depth in meters, ASF=Age Scaling Factors.
Recommended age scaling factors (ASF) based on Andrus et al. (2003) are provided
in Table 4.2.
Table 4.2 Recommended Age Scaling Factors (ASF) for SPT(Andrus et al., 2003)

Geologic Age andFines Content,

Age Scaling

Database Range of Shear

Location of Deposit

FC (%)

Factor, ASF

Wave Velocity, vs (m/s)

< 40%

1.00

110 – 260

10% to 35%

1.00

120 – 240

< 10%

1.00

110 – 260

< 40%

1.23

150 – 270

10% to 35%

1.08

160

< 10%

1.28

150 – 270

< 40%

1.82

340

10% to 35%

1.71

340

< 40%

1.59

330 – 350

10% to 35%

1.48

330 – 350

Holocene
Coastal Plain
Pleistocene
Coastal Plain
Tertiary
Coastal Plain
Ashley Formation
Tertiary
Coastal Plain
Dry Branch Formation
FC=% passing #200 sieve

The procedures of estimating shear wave velocity, vs, from SPT data are following:
1. Estimating FC(%) of soil layer at SPT depth60

CHAPTER 4

METHODS FOR DETERMINING DYNAMIC PARAMETERS OF SOIL

2. Calculating SPT blow count (N*60) and Age Scaling Factor (ASF) based on Fine
Content (FC) at each depth of SPT (Z)
3. Estimating vs, from (4.4), (4.5), (4.6) equation with FC(%) and correlation depth of
SPT (Z)
4. Drawing relation between vs and Z
A review of SPT calculated shear wave velocity relationships reveals that few
relationships have been developed for clays. This is likely due to SPT blow counts (N)bot being the appropriate test for cohesive soils, particularly since soft clays would have
SPT blow counts that would be close to zero. This results in the shear wave velocity that
also would be close to zero.
Estimation of shear wave velocity, vs, from CPT data

4.4.2

Recommended equations to estimate shear wave velocity, vs, for soils are based on
CPT tip resistance (qc), depth (Z), soil behavior type (Ic), geologic age and location ofdeposit, and Age Scaling Factor (ASF). Equations for estimating shear wave velocity, vs,of soils provided in Table 4.3.
Table 4.3 CPT (qc) – Shear Wave Velocity, vs, Equations for Soils(Andrus et al., 2003)

Soil Behavior Type, Ic

Equation for Predicting vs (m/s)

Equation No

All value𝑣

4.63𝑞 .

𝐼 .

𝑍 .

𝐴𝑆𝐹

4.7

< 2.05𝑣

8.27𝑞 .

𝐼 .

𝑍 .

𝐴𝑆𝐹

4.8

> 2.6

𝑣

0.208𝑞 .

𝐼 .

𝑍

𝐴𝑆𝐹

4.9

.

Recommended age scaling factors (ASF) depended on soil behavior type (Ic) and
depth (Z) are provided in Table 4.4 (Andrus et al., 2003)
The soil behavior index, Ic depended on the normalized cone resistance, Q, and thenormalized friction ratio, F, are computed using the following equation:
𝐼

3.47

𝑙𝑜𝑔𝑄

1.22

.

𝑙𝑜𝑔𝐹

(4.10)

Where:
Q.

(4.11)

61

CHAPTER 4

METHODS FOR DETERMINING DYNAMIC PARAMETERS OF SOIL

F

100%

(4.12)

Where:
qc – CPT Tip Resistance (kPa)Fs – CPT Skin Resistance (kPa)Pa – Reference Stress = 100 kPa = 1 atm
𝜎 - Effective Vertical or Overburden Stress (kPa)n – Exponent ranging from 0.5 to 1.0 depended on computing procedure of soil
behavior index.
Table 4.4 Recommended Age Scaling Factors (ASF) for CPT(Andrus et al., 2003)

Database

Soil

Age

Behavior

ScalingType Index,

Factor,Ic

ASF

All soils

All values

1.00

60 – 260

Clean sand, silty sand< 2.05

1.00

110 – 260

Clay, silty clayey silt, silty clay

> 2.601.00

60 – 230

All soils

All values

1.23

450 – 1000

Clean sand, silty sand< 2.05

1.34

500 – 1000

Clay, silty clayey silt, silty clay

> 2.601.16

450 – 1000

All soils

All values

2.29

230 – 540

Coastal Plain

All soils

All values

1.65

310 – 350

Tobacco road

Clay, silty clayey silt, silty clay

> 2.601.42

330 – 350

Coastal Plain

All soils

All values

1.38

310 – 360

Dry branch

Clean sand silty sand< 2.05

1.33

310 – 360

Geologic Ageand Location

Soil behavior Descriptionof Deposit

Holocene
Coastal Plain
Pleistocene
Coastal Plain

Range of
Shear Wave
Velocity, vs(m/s)

Tertiary
Coastal Plain
AshleyFormation
Tertiary

Formation
Tertiary

Formation

62

CHAPTER 4

METHODS FOR DETERMINING DYNAMIC PARAMETERS OF SOIL

The procedure for estimating the soil behavior index is following:
1. Calculate soil behavior index, Ic, using equation (5.10) with n=1.0 to have Ic=Ic1
2. If soil behavior index, Ic, is > 2.60, use computed Ic using n=1.0
3. If soil behavior index, Ic, is < 2.60, recalculate Ic using n=0.50
a. If the recalculated Ic is < 2.60, use computed Ic using n=0.50
b. If the recalculated Ic is > 2.60, recalculate Ic using n=0.70
4. End.
In brief, the estimating procedures of shear wave velocity, vs, from CPT data arefollowing:
1. Obtain qc (kPa) and fs (kPa) at depth, Z, of CPT
2. Calculate 𝜎 (kPa) at depth, Z,
3. Calculate soil behavior index Ic at depth, Z, using equation 4.10
4. Use Table 5.4 to obtain age scaling factor (ASF) from correlated Ic
5. Estimate vs using 4.7, 4.8, or 4.9 from correlated Ic
4.4.3

Estimation of damping ratio

Damping ratio is a measure of energy dissipation and increases with increase in shear
strain amplitude. The damping ratio increases slowly at a low strain level and thenincreases quickly with increasing strain amplitude. Damping is induced in soil due to thefriction between the soil grains, viscous drag between the pore fluid and soil grains, andplastic deformation of the soil grains. The soil grains are very stiff and tend to keep theirelasticity at high confining pressure, and thus very little energy dissipates through plastic
deformation. In general, the damping ratio of soil is affected by a lot of factors (Ishibashi
and Zhang, 1993; Karl, 2005; Zhang et al., 2005) such as effective confining pressure,void ratio, plastic index, stratum age, and loading condition. Therefore accurate
estimation of the damping ratio considered all factor is a complex work. In 1993, Ishibashi
and Zhang have proposed an equation for estimating the damping ratio of soil based onplastic index, effective confining pressure, and shear strain amplitude. The authors
reanalyzed the available experimental data and an attempt is made to establish unified
formulas for dynamic shear moduli and damping ratio to cover wide variety of soils
ranging from sands to highly plastic clay.
The formula for estimation of damping ratio is expressed as following:63

CHAPTER 4h

METHODS FOR DETERMINING DYNAMIC PARAMETERS OF SOIL
.

0.333

.

.

0.586

1.547

1

(4.13)

where:𝐾 𝛾, 𝑃𝐼 𝜎,(4.14)

PI: Index plastic of soil (%)γ: Medium shear strain amplitude (%)
𝜎 : mean effective confining pressure
𝐾 𝛾, 𝑃𝐼

0.5 1

𝑚 𝛾, 𝑃𝐼𝑚𝑛 𝑃𝐼

𝑡𝑎𝑛ℎ 𝑙𝑛
0.272 1.

.

𝑡𝑎𝑛ℎ 𝑙𝑛.

(4.15).

𝑒.

.

0.0 𝑓𝑜𝑟 𝑃𝐼 0 𝑠𝑎𝑛𝑑𝑦 𝑠𝑜𝑖𝑙
3.37 10 𝑃𝐼 . 𝑓𝑜𝑟 0 𝑃𝐼 15 𝑙𝑜𝑤 𝑝𝑙𝑎𝑠𝑡𝑖𝑐 𝑠𝑜𝑖𝑙𝑠.
𝑓𝑜𝑟 15 𝑃𝐼 70 𝑚𝑒𝑑𝑖𝑢𝑚 𝑝𝑙𝑎𝑠𝑡𝑖𝑐 𝑠𝑜𝑖𝑙𝑠⎨7.0 10 𝑃𝐼⎪
2.7 10 𝑃𝐼 . 𝑓𝑜𝑟 𝑃𝐼 70 ℎ𝑖𝑔ℎ 𝑝𝑙𝑎𝑠𝑡𝑖𝑐 𝑠𝑜𝑖𝑙𝑠⎩⎧⎪(4.16)(4.17)

Using the above formulas to calculate the damping ratio for sandy soil and medium
plastic soils with PI of 35 % in case of 𝜎 =10 kPa and 400 kPa, respectively, the results
are shown in Figure 4.3 and 4.4.
𝜎 =400 kPa

h(,PI)h(,PI)𝜎 =10 kPa

Figure 4.8 h~ relation of sandy soils (PI = 0 %)64

CHAPTER 4

METHODS FOR DETERMINING DYNAMIC PARAMETERS OF SOIL

𝜎 =400 kPa

h(,PI)h(,PI)𝜎 =10 kPa
Figure 4.9 h~ relation of plastic soils (PI = 35 %)4.5

SUMMARY
An analytical procedure for estimation of the soil dynamic parameters in conformity

with current condition of Vietnam based on the methods of previous researches in theworld has been suggested. The following conclusions were derived based on thecalculated results.
The estimation of the soil dynamic parameters based on CPT data with low cost is
feasible at current situation in Vietnam.
The methods for estimation of the soil dynamic parameters based on SPT, CPT databring a feasible research direction for evaluation and establishment of soil dynamic
parameters in Vietnam in application for dynamic problems.

REFERENCES
Das, B. M. (1995): Principles of soil dynamic, PWS-KENT, publishing company, USA.
Kramer, S. L. (1996): Geotechnical Earthquake Engineering, Prentice Hall, New Jersey.
Verruijt, A. (1994, 2008): Soil dynamic, Delft University of Technology.
Karl, L. (2005): Dynamic soil properties out of SCPT and bender element test withemphasis on material damping, A thesis of doctor of philosophy in Ghent University.
Schneider, J. A., Hoyos, L., Mayne, P. W., Macari, E. J., and Rix, G. J. (1999): Field
and laboratory measurements of dynamic shear modulus of piedmont residual soils,
Behavioral characteristics of residual soils, GSP 92, ASCE, Reston, VA, pp.12-25.
Kavazanjian, E., Matasovib, J. N., Hadi-Hamou, T., and Sabatini, P. J. (1997):
Geotechnical Engineering circular No 3 Design guidance geotechnical engineering,
Earthquake engineering for highway, Vol.I design principle.

65

CHAPTER 4

METHODS FOR DETERMINING DYNAMIC PARAMETERS OF SOIL

The South Carolina Department of Transportation (SCDOT) (2010): Geotechnicaldesign manual – version 1.1, chapter 12, Geotechnical Earthquake Engineering, Final.
Ishibashi, I., Zhang, X. (1993): Unified dynamic shear moduli and damping ratios ofsand and clay, Japanese Society of soil Mechanics and Foundation Engineering, Soil andFoundations, Vol.33, No.1, pp.182-191.
Zhang, J., Andrus, R. D., and Juang, C. H. (2005): Normalized shear modulus andmaterial damping ratio relationship, Journal of geotechnical and geoevironmental
engineering, ASCE/April 2005.
Till, J. J. Hanebuth, Yoshiki, S., Susumu, T., Quang, L. V., and Quang, T. N. (2005):
Sea levels during late marine isotope stage 3 (or older?) reported from the Red River delta(northern Vietnam) and adjacent regions, Quaternary International, 145–146 (2006) 119–
134.
Trinh, V. B., Dinh, V. T., Nguyen, T. H. Q., Lai, H. P., Bui, H. D. (2003): Estimationof soil and rock elastic parameters for high-rise building design at Caugiay of Hanoi cityby seismis survey in boring hole, Proc. of the 2nd Vietnam National Conf. on problems ofbuilding (in Vietnamese).
Trinh, V. B., Dinh, V. T., Lai, H. P., Tran, A. V. (2011): Influence of earthquake onsoil condition in west area of Hanoi, Earth Science Journal (in Vietnamese)

66

Chapter 5

STUDY ON VEHICLE-INDUCED VIBRATION

5.1

INTRODUCTION

Vietnamese government had the plan that Hanoi’s transport plan aims to increase theshare of public transport from the current low figure of 9 % of trips, to above 60 % by2030, by which time Hanoi city is slated to have six new metro and three Bus Rapid
Transit (BRT) lines. Vietnamese government hopes both traffic and environmental issues
can be tackled. It is forecasted that a huge quantity of excavated soil will be discharged
from the projects in Hanoi city over the next decade. Therefore, it will become more andmore difficult to find reclamation sites for the soil to dump around the city from theenvironmental point of view. In Japan, LSS is effective backfilling method for using
excavated soil in construction work and LSS has been popular as a recycling method for
excavated soil. However, LSS indicates a brittle characteristic when the strength
increments as increasing an amount of cement stabilizer. In order to improve ductile
performance of LSS, a reinforcement method has been created by mixing newspaper as afiber material into LSS.
LSS was produced by adding and mixing cement stabilizer into liquefied stabilized
soil with hand mixer. In the production process, the determination of the density was
performed by measuring the mass of slurry filled into a stainless steel mold of 400 cm3
called “AE mortar container”. After achieving the desired density, fiber material withamount of 10 kg/m3 was added and mixed by hand mixer.

In order to determine fluidityof LSS, the flow test was performed in accordance with JHS A313– Japan Highway
Public Corporation Standard. Moreover, the fresh LSS is made to be removed the air
inside specimen applying vacuum. However, an investigation on the induction of vehicleinduced building vibration by using LSS has not been performed.

67

CHAPTER 5

5.2

STUDY ON VEHICLE-INDUCED VIBRATION

DEFINITION OF VIBRATION LEVEL

Vibration level is estimated from three parameters as displacement, velocity andacceleration. In Vietnam, vibration velocity is used to estimate the vibration level as anapplication standard. The abbreviation “VdB” is used for vibration decibels to reduce thepotential for confusion with sound decibels (FTA, 2006). Accordingly, maximum
vibration level is computed as following (SP, 2004):
L

max 𝐿

L [VdB]

(5.1)

VdB

5.2

∑ 𝑣 [m/s]

(5.3)

[m/s]

(5.4)

Where:
L

20log

𝑣
𝑣

𝑣

𝑣

L: Maximum vibration level
𝐿 : Vibration level with time at time interval of ith one-second[L]: Criteria for acceptable level of vibration𝑣 : Root mean square vibration velocity of measurement point at ith one-second𝑣: Reference vibration velocity, 𝑣

𝑡𝑡

5. 10 m/s (SP, 2004)

1s (FTA, 2006; SP, 2004; Kurbatskii, 2008)

𝑓 : Number of measured velocity data within one-second period
𝑣 ,𝑣 ,𝑣 : 𝑛

Horizontal, vertical, and total vibration velocity at measurement

point
According to Russia standard being used in Vietnam at present, the vibration
prediction for building is assessed from the value of velocity at top of foundation (SP,2004). Therefore, this chapter uses the velocity value at the ground surface to predict thevibration.
National Technical Regulation on Vibration has been promulgated by Natural
Resources and Environment in 2010 (QCVN 27, 2010). The regulation gives criteria for
acceptable levels of ground-borne vibration from any source such as trains, buses onrough roads, and constructions activities, blasting, pile-driving and operating heavy earthmoving equipment for residence. The maximum permissible level of vibration is assigned
68CHAPTER 5STUDY ON VEHICLE-INDUCED VIBRATION

to be 75VdB. The value is also found in reports of Japan. The results of the Japanesestudy confirm the conclusion that at a vibration velocity level of 75 to 80 VdB, many
people will find the vibration annoying (Tokita, 1975).
5.3

ANALYTICAL AND NUMERICAL APPROACHES

5.3.1 Vehicle motion
A single-axle quarter-truck vehicle with 2- degree of freedoms (DOFs) running on arough road at constant velocity V was reported. The static loads is not considered in thisstudy. Only cyclic loads are determined. Therefore, the equation of motion associate withthe body of the vehicle as follows:
𝑚
0

0
𝑚

𝑘

𝑍 𝑡
𝑍 𝑡

𝑘

𝑘
𝑘

𝑘

where 𝑐 and 𝑘

𝑐
𝑐

𝑍 𝑡
𝑍 𝑡
𝑐 𝑦 𝑡

0

𝑐

𝑐

𝑐

𝑘 𝑦 𝑡

𝑍 𝑡
𝑍 𝑡
(5.5)

are respectively the damping and stiffness coefficients of thesuspension system; 𝑚 and 𝑚 are the sprung and unsprung masses, respectively; 𝑐and 𝑘 are the damping, stiffness coefficients of the tire, respectively; 𝑍 is the absolute
acceleration; 𝑍 is the absolute velocity; Z is the absolute displacement associated withthe vertical vibration of the vehicle body; y is the roughness of road pavement.
After modal analysis, Eq. (5.5) can be written in solution as:
𝑍 𝑡

𝜑,

𝑌 𝑡

𝜑,
𝜑 ,

𝜑,
𝜑 ,

𝑌 𝑡
𝑌 𝑡

(5.6)

where φ , is the ith component of the jth mode shape and φ , is the jth modal
coordinate of the system.
5.3.2

Road Spectrum

The equation of LaBarre et al.18) describes the first road spectrum model as follows:

S

ω

S n

, ω

2πVn

S n

, ω

2πVn

(5.7)

where 𝑛 , 𝑤 , 𝑤 are shape coefficients; ω is circular frequency; S nroughness coefficient and V is vehicle velocity.
69

is the road

CHAPTER 5STUDY ON VEHICLE-INDUCED VIBRATION

5.3.3 Vehicle loads on pavement
Vehicles running on rough roads can be caused vertical vibrations. Cyclic vehicle load
F(t) can be determined as follows:
𝑚 𝑍 𝑡

𝐹 𝑡

𝑚 𝑍 𝑡

(5.8)

In linear system, if the cyclic vehicle load F(t) will be stationary Gaussian random
processes with zero, Eq. (A5) is obtained from Eq. (A2) and (A4) as follows:
𝑌 𝑡
𝑌 𝑡
𝑚 𝜑 , 𝜑 ,𝑌 𝑡
𝑌 𝑡 (5.9)
The total vehicle load F(t) can be calculated the following equation:
𝐹 𝑡𝑚 𝜑, 𝜑,

𝐹 𝑡

𝑚

𝑚 𝑔

𝐹 𝑡

(5.10)

5.3.4 Cyclic vehicle loading spectrum
Closed-form solution for the cyclic load spectrum 𝑆

was proposed by Lin as

follows:
𝑆

𝑇 𝜔

𝜔

𝜔 𝑐

𝑇 𝜔 𝑆

𝜔

(5.11)𝑘𝑚𝑚

𝜑, 𝜑 , 𝜑 , 𝜑 ,𝑅𝑒 𝐻 𝜔 𝐻𝑀𝑀𝜔
(5.12)Re H ω H



ω







(5.13)
where  is the jth modal damping ratio of

the system and 𝜔 is the undamped natural

frequency of the jth modal.
5.3.5 Generation of a time history of cyclic vehicle loading
During pavement response analysis, the time history of cyclic vehicle load F(t) can be
simulated from Eq. 5.11:
𝐹 𝑡

∑

𝑆

𝜔 ∆𝜔 𝑠𝑖𝑛 𝜔 𝑡70

𝜃

(5.14)

CHAPTER 5STUDY ON VEHICLE-INDUCED VIBRATION

where 𝜃 is a random phase angle uniformly distributed from 0 to 2; 𝜔 is circularfrequency; the frequency increment ∆𝜔𝜔frequency increments within the frequency interval (𝜔defined.𝜔

and 𝜔

𝜔 ; N is the total number of,𝜔in which 𝑆

𝜔 isare minimum and maximum frequencies, respectively.

5.3.6 Verification
To demonstrate the accuracy application of the cyclic vehicle loads, many researchers
simulated a moving load on pavement surface. Hamdy et al. evaluated the cyclic responseof asphalt-concrete pavement reinforced with geogrid using cyclic load amplitude of 400
kPa.
Agostinacchio et al. used a Matlab® approach to investigate the vibration induced bysurface irregularities in road pavement. The behavior of the cyclic load for the various
vehicles travelling at chosen speeds on the different road surfaces profiles was generated
in accordance with ISO 8608 Standard22). The maximum cyclic load produced by a truck
is approximately 310 kN.
In addition, Lin J. H simulated cyclic vehicle load on road pavement. The relationshipbetween maximum cyclic vehicle load and the grade of surfaces on roads of various
classes is shown in

Figure 5.1 Relationship between maximum cyclic vehicle load andthe grade of surfaces on roads of various classes

71

CHAPTER 5

5.4

STUDY ON VEHICLE-INDUCED VIBRATIONANALYSIS PROCEDURE

In order to predict the ground-borne vibration due to moving vehicle on road system
in Hanoi city, a 2D finite element model was developed in this study. Plaxis is a program
based on finite element method (FEM). The program was originally developed at the
University of Delft in Netherland where research in geotechnical design based on FEM
in the ‘70s resulted in a commercial version of the program in 1987 and since 1998 it isavailable in a Windows version with a user-friendly interface. The program can simulate
problems with the most common construction element such as beams and struts. Today,
the program is practical for solving most complex geotechnical problems. The programis divided into four sub-programs (Input, Calculation, Output and Curves) (Brinkgreve etal., 2006). From these features, use of Plaxis in geotechnical design works has been
becoming widely in Vietnam at present.
However, as using Plaxis in order to solve problems of soil-road interaction underdynamic loading induced by moving train, the program has not sufficiently provided
calculation tools as following:-

Dynamic load described in the program is harmonic ones and other cases of load
including vehicle-induced dynamic load require the definition by user.

72

CHAPTER 5STUDY ON VEHICLE-INDUCED VIBRATION

From the above background, this study has proposed an analysis procedure for the
ground-borne vibration prediction as shown in Figure 5.2.
- Ground conditions- Material Properties- Dynamic parameters of soil

- Profile of road- Road structure- Parameters of Road

PLAXIS
Determination of natural
frequency by Fourier
spectrum method- Analysis model- Analysis- Result

Simulation of vehicleinduced dynamic loading

Data processing

Applied Standard

Vibration prediction

End, L

Figure 5.2 Schematic diagram of prediction procedure for train-induced vibration from road

5.4.1 Selection of material model
Generally, medium model is the set of relations describing properties the medium in aprocess. The model should allow using mathematical language to describe thefundamental behaviors of the medium under loading with high accuracy and reliability.
Nowadays, many sophisticated medium models can simulate soil behaviors, which isvaried its state during loading. The models with other variables have being improved
together with progress of scientific and technology. However, models should be as simple
as possible and as accurate as necessary regarding the task they serve. With soil model, it
should describe main properties of soil, uniquely defined in term of mathematics and beeasy for use of mathematical function. In addition, the model should be practical incurrent condition, which requires the soil parameters for input data as few as possible.
Recently, based on the results of study on soil kinds in South Asia area by Plaxis andexperiment, Ahmad (2010) and Bahatin (2008) have reported that Mohr Coulomb modeland Hardening Soil model agree well with experiment results and shows almost not any
distinction in analysis with friction soils. Bui (2007) proposed use of modified Cam Clay73

CHAPTER 5STUDY ON VEHICLE-INDUCED VIBRATION

model for weak soil layers in Hanoi area. Moreover, the soil parameters for the Mohr
Coulomb and modified Cam Clay models can be obtained from data of geologic survey
reports in current condition of Vietnam. Therefore, this is the reason why this study use
modified Cam-Clay model for weak soil and Mohr-Coulomb for other soil to analyze in
Plaxis.
The models and their parameters described in detail can be availably found in literature(Fadeev, 1995; Brinkgreve et al., 2006; Kojic, 2005; Helwany, 2007). The parameters ofthe models for analysis in Plaxis can be classified into two groups, basic parameters andparticular ones of each model. The basic parameters can be easily obtained from basic
test of soil samples such as unit weigh (), two Rayleigh coefficient (𝛼angle (φ), cohesion (c), and dilatancy angle (ψ). ψ
clay; ψφ30 is for sand; ψ& 𝛽 ), friction

0 is for overconsolidated soil,

0 is for soil kinds with φ

0 (Brinkgreve, et al.,2006).
Mohr-Coulomb model parameters:
Beside the aforementioned parameters, Mohr-Coulomb model requires more twoparameters including Young modulus (Eeq), Poisson’s ratio (ν) as shown in Figure 6.3,
which can be obtained from geologic survey reports or basic test of soil sample. The twoparameters can be estimated in Plaxis by means of equation (5.1), (5.2), and (5.3) as
providing shear wave velocity (vs) and compressive wave velocity (vp).
Modified Cam-Clay model parameters:
Modified Cam Clay model was made based on five particular parameters as shown in
Figure 6.4. The parameters including Poisson’s ratio (𝜈 ), Cam-Clay swelling index (κ),
Cam-Clay compression index (λ), Tangent of the critical state line (M), initial void ratio(einit) can be obtained from basic test of sol sample. Poisson’s ratio 𝜈

is a real elastic

parameter and not a pseudo-elasticity constant as used in the Mohr-Coulomb model. Itsvalue will usually be in range between 0.1 and 0.2 (Brinkgreve, et al., 2006). Compression
index and swelling index can be obtained from one-dimensional consolidated
compression test as following:
λ

and κ

)

(5.16)

74

CHAPTER 5STUDY ON VEHICLE-INDUCED VIBRATION

he parameter M should be based on the friction angle and estimated from plastic conditionof Mohr-Coulomb as following:M.

(5.17)

Figure 5.4 Mohr-Coulomb model parameters in Plaxis

Figure 5.3 Cam-Clay model parameters in Plaxis75CHAPTER 5

5.5

STUDY ON VEHICLE-INDUCED VIBRATIONNUMERICAL MODEL AND CONSIDERED PARAMETERS

The road system of Hanoi city as operated will generate ground vibrations which cause
undesirable environment and economical impacts such as nuisance of the passenger along
the road and deterioration of the alongside existing building structures. On the other hand,the vehicle-induced vibration problem has been not sufficiently mentioned inenvironmental impact assessment. Therefore, Giai Phong road, Dong Da district inHanoi city was selected to analyze the train-induced vibration in this study.
5.5.1 Road and ground conditions
Giai Phong road is one of main road in Hanoi city and it is the main connection roadfrom Hanoi to north-south highway of Vietnam. Because, the road was constructed andused. In addition, the purpose of this study is to analyze reduction of vehicle-induced
vibration using liquefied stabilized soil. Therefore, two types of soils were used forbackfilling process. The geotechnical properties of soil layers in the line are shown in
Table 5.1. The soil dynamic parameters have been calculated as shown in Table 4.10 and
4.11 of Chapter 4. The parameters of the road are shown in Table 5.2.
M aterial

Unit

Constitutive model
Thicknessm2

Asphalt concrete

Base(Crushed stone)

Sub-base(Crushed stone)

Sub-grade(Sand)

Linear elastic

M ohr-Coulomb

M ohr-Coulomb

M ohr-Coulomb

0.1

0.3

0.4

0.4

3

2

M N/m

2.1x101.2x1049

24

Poisson' ratio

-

0.45

0.35

0.3

0.3

Dry density

kN/m3

20

20

18

17

Saturated density

kN/m3

-

22

20

18

2

-

30

20

0

Young’s modulus

CohesionkN/m

Friction angle

Dgree

-

43

40

35

Dilatation angle
Coefficient of
Hortizontal permeability
Coefficient of
Vertical permeability

Degree

-

13

14

5

-

1

1

1

-

1

1

1

kx

-

ky

-

Table 5.1 Material properties of road

Table 5.2 Geotechnical properties of soil layers

76CHAPTER 5STUDY ON VEHICLE-INDUCED VIBRATION

5.5.2 Finite element model
In this study, a 2D model of road, building, surrounding soil and cyclic loading ofvehicles on the road with the use of Plaxis V8.6 finite element software is introduced inorder to evaluate vibration propagation due to passing of vehicles to the ground surface.

B

A

G

E

C
D

F

H

Figure 5.5 Finite element model in Plaxis

5.6

SUMMARY

Within this chapter, an analysis procedure for prediction of vehicle-induced vibration
has been performed in conformity with current condition of Vietnam. Two types ofbackfill soils were selected and analyzed in this study. According to the results of thenumerical analysis, the following conclusions are reached in regard to the road induced
vibrations in Vietnam.
Based on Bernoulli-Euler beam theory, a model of the dynamic loading on tunnel has
been made. Its numerical simulation procedure was accomplished in Mathcad byprogramming. The numerical result with high reliability can be input data for groundborne vibration analysis model.
Use of Plaxis a program being popular in Vietnam with application of Fourier
spectrum method to estimate natural frequency for dynamic problem of multilayered
ground system bring the reliable results

REFERENCES
Tokita, Y. (1975): Vibration Pollution Problems in Japan, In Inter-Noise 75, Sendai,
Japan, pp.465-472.
Fadeev, A. B. (1995): Finite element method in geotechnical engineering, Education
Publishing House (translated in Vietnamese)77

CHAPTER 5STUDY ON VEHICLE-INDUCED VIBRATION

Bathe, K. J. (1982): Finite element procedures in engineering analysis, Prentice-Hall
Inc, Englewood Cliff, New Jersey, USA.
Zienkiewicz, O. C. and Taylor, R. L. (2000): The finite element method, Vol.1: The
basic, Butterworth-Heinemann, A division of reed education and professional publishingLtd.
Zienkiewicz, O. C. and Taylor, R. L. (2000): The finite element method, Vol.2: Solidmechanics, Butterworth-Heinemann, A division of reed education and professional
publishing Ltd.
Nguyen, T. L. (2005): Study on interaction of nonlinearity dynamic in structure andground, PhD. Dissertation, Le Quy Don Technical University of Hanoi (in Vietnamese).
Nguyen, T. T. (2005): Study on interaction in structure and medium under loading of
weapons with consideration of nonlinearity of medium, PhD. Dissertation, Le Quy Don
Technical University of Hanoi (in Vietnamese).
Carl E. H., David A. T., Lance D. M.: Transit noise and vibration impact
assessment, U.S. Department of Transportation Federal Transit

Administration-Office of Planning and Environment 1200 New Jersey
Avenue, S.E. Washington, DC 20590, 2006.
SP 23-105.: Estimation of vibration in design, construction and operationof underground, Code of practice for design and construction, Russian Metro
Standard, 2004.
Kurbatskii, G. H.: Measurement of vibrations, Moscow State University ofRailway Engineering, 2008.
QCVN 27:2010/BTNMT.: National Technical Regulation on Vibration,
Ministry of Natural Resources and Environment of Vietnam, 2010 (inVietnamese).
Tokita, Y.: Vibration Pollution Problems in Japan, Proceedings Inter-Noise‘75, Tohoku university, Sendai 980, Japan, pp.465-472, 1975.
Duong, H. Q., Kohata, Y., Nguyen Q. D.: Evaluation on Mitigation of Traininduced Vibration as Using LSS for Backfilling Ground of Cut and CoverTunnel by FEM, the 50th Japan National Conference on GeotechnicalEngineering, pp.2411-2412, 2015.
Das, B. M.: Principles of soil cyclic, PWS-KENT, publishing company, USA,1995.
TCXDVN.: Design of structure for earthquake resistance, construction
standard of Vietnam, p.1, regulations, earthquake impact with building
structure, 2006 (in Vietnamese).
Railway Technical Research Institute: Explanation for railway structureand design standards, 1999.
78

CHAPTER 5STUDY ON VEHICLE-INDUCED VIBRATION

Rao,

SS.: The Finite
Element
Methods in Engineering,
Edition, Pergamon Press, New York, 1989.

SecondLin J.H.: Simulation of cyclic vehicle load on road pavement,
Vibroengineering PROCEDIA, Vol. 5, 2015, p.p 503-508, 2015.
LaBarre R. P., Forbes R. T., Andrew S.: The measurement and analysis ofroad surface roughness. Motor Industry Research Association, Report No.
5/1970, Nuneaton, England, 1970.
Lin J. H.: Variations in cyclic vehicle load on road pavement, International
Journal of Pavement Engineering, Vol. 15, p. 558-563, 2014.
Hamdy F., Ahmed M. H.: 2D plaxis finite element modeling of asphaltconcrete pavement reinforced with geogrid. Journal of Engineering Sciences,Vol. 42 No. 6, pp. 1336 – 1348, 2014.
Agostinacchio M., Ciampa D., Olita S.: The vibrations induced by surface
irregularities in road pavements – a Matlab® approach, DOI 10.1007/s12544013-0127-8, 2014.
ISO 8608: Mechanical vibration, road surface profiles- Reporting of
Measured Data, 2016.

79

Chapter 6

REDUCTION OF VEHICLE-INDUCED VIBRATION USING
LIQUEFIED STABILIZED SOIL

6.1

INTRODUCTION

Vietnamese government had the plan that Hanoi’s transport plan aims to increase theshare of public transport from the current low figure of 9 % of trips, to above 60 % by2030, by which time Hanoi city is slated to have six new metro and three Bus Rapid
Transit (BRT) lines. Vietnamese government hopes both traffic and environmental issues
can be tackled. It is forecasted that a huge quantity of excavated soil will be discharged
from the projects in Hanoi city over the next decade. Therefore, it will become more andmore difficult to find reclamation sites for the soil to dump around the city from theenvironmental point of view. In Japan, LSS is effective backfilling method for using
excavated soil in construction work and LSS has been popular as a recycling method for
excavated soil. However, LSS indicates a brittle characteristic when the strength
increments as increasing an amount of cement stabilizer. In order to improve ductile
performance of LSS, a reinforcement method has been created by mixing newspaper as afiber material into LSS.
LSS was produced by adding and mixing cement stabilizer into liquefied stabilized
soil with hand mixer. In the production process, the determination of the density was
performed by measuring the mass of slurry filled into a stainless steel mold of 400 cm3
called “AE mortar container”. After achieving the desired density, fiber material withamount of 10 kg/m3 was added and mixed by hand mixer.

In order to determine fluidityof LSS, the flow test was performed in accordance with JHS A313– Japan Highway
Public Corporation Standard. Moreover, the fresh LSS is made to be removed the air
inside specimen applying vacuum. However, an investigation on the induction of vehicleinduced building vibration by using LSS has not been performed.

80

CHAPTER 6 REDUCTION OF VEHICLE-INDUCED VIBRATION USING
LIQUEFIED TABILIZED SOIL

In this study, the investigation is focused on the effect of using LSS for reduction of
nearby building responses based on a parametric study directly in the time domain. Twocases i.e. the use of backfilling soil and LSS for backfill ground of building towards GiaiPhong road, Dong Da district in Hanoi city was evaluated by using the numerical analyses
procedure.
6.2
6.2.1

ANALYSIS PROCEDURE

Simulation of cyclic vehicle load

In this paper, the investigation is focused on the effect of using LSS for the reductionof nearby building responses through a parametric study. The cyclic vehicle load on roadpavement was directly considered in the mathematical modeling and analysis. Some
details are given in Chapter 5. Therefore, as differences from others, the cyclic vehicle
load is automatically taken into account and the effect of LSS reinforced with paper isevaluated directly. Responses of the building and backfilling materials are given in termsof accelerations.
In this study, vertical vibrations can be produced during moving vehicles on roughsurface of the roads, thereby the transmitting of the inertial force is associated with thevibration through the suspension system and wheels into the pavement. This study was
analyzed under 400 kN/m in moving load of vehicles and 10 Hz in frequency when thecyclic load is applied to pavement on the truck with a speed of 60 km/h.
6.2.2

Numerical model and considered parameters

In this study, a reinforced concrete eight-floor building frame with one basement was
selected and the model is shown in Figure 6.1.
1- Building, road and ground conditions
The building of 12 m in width and 24 m in height is located to the right hand side of
the road. The structure shown in Figure 6.1 is a part of the building that is formed by aseries of parallel frames. The height of the floors is 3 m and the basement floor is locatedat a depth of 4.5 m below ground surface. The frame consists of three bays of 4 m indistance. The distance from left end of building to the right end of the road were assumed
to be 15.5 m. The pile foundation is selected to analyze in this study. The excavated area81

CHAPTER 6 REDUCTION OF VEHICLE-INDUCED VIBRATION USING
LIQUEFIED TABILIZED SOIL

shown as “Backfilling material” in Figure 6.1 was set to 4.5 m in depth equal to the heightof basement floor and 10 m in width, which is considered to be reduced a vehicle-inducedbuilding vibration from the previous study. In this study, back filling soil as Case 1 and
LSS as Case 2 were selected as backfilling materials, and the reducing effect on building
on building vibration is discussed. The ground profile of construction area areschematically shown in Figure 6.2. The geotechnical properties of soil layers are shownin Table 6.1. The ground was composed of soft clay and loose sand from the surface tothe depth of 30-40 m, and of dense sand or gravel below the depth of 30-40 m.
12.0

3.0
1.5

15.0

5.5

10.0

40.0

15.0

4.5

4.5 3.0

3.0

24.0

3.0

4.0 4.0 4.0

Figure 6.1 Numerical model of the considered soil structure system

Table 6.1 Parameters of building

Table 6.2 Geotechnical properties of soil layers

82CHAPTER 6 REDUCTION OF VEHICLE-INDUCED VIBRATION USING
LIQUEFIED TABILIZED SOIL

Vs=168 m/s
ρ=17 kN/m3
Vs=210 m/s
ρ=15 kN/m3

7.0

Vs=165 m/s
ρ=15 kN/m3
Vs=212 m/s
ρ=15 kN/m3

Vs=275 m/s
ρ=19 kN/m3

Vs=369 m/s
ρ=20 kN/m3

Figure 6.2 Ground profile

Damping ratio of soil layers is assumed to be 4 %, which is in range of 3-8 %, thevibration level of ground is not significantly changed13). Also, most soil types in Hanoi
area have the damping ratio in range of 3-5 %. Poisson's ratio of all soil layers and thebackfilling materials were assumed to be 0.49. The shear elastic wave velocity of ground
was calculated from N-value, using the formula of Japanese railway standard. The
parameters of building are shown in Table 6.2.
Figure 6.3 shows typical cross section of Giai Phong road where the total thickness of
the road embankment is 1.2 m. The thickness of subgrade soil is 0.4 m, sub-base layer is
0.4 m, base layer is 0.3 m and asphalt concrete is 0.1 m, respectively. The total width of
the road is 38 m, in which 30 m for traffic including two lanes and 8 m for the sidewalk.
This road is one of main road in Hanoi city and it is the main connection road from Hanoi
to north-south highway of Vietnam. Material parameters and constitutive model are
shown in Table 6.3.

0.3 0.1 (m)Base layer

0.4

Sub-base layer

0.4

2- Characteristics of backfilling materials

Subgrade soil

Asphalt concrete

Figure 6.3 Typical cross section of Giai Phong road83CHAPTER 6 REDUCTION OF VEHICLE-INDUCED VIBRATION USING
LIQUEFIED TABILIZED SOIL

Table 6.3 Material properties of roadM aterial

Unit

Constitutive model
Thickness

Asphalt concrete

Base(Crushed stone)

Sub-base(Crushed stone)

Sub-grade(Sand)

Linear elastic

M ohr-Coulomb

M ohr-Coulomb

M ohr-Coulomb

0.1

0.3

0.4

0.4

m
2

Young’s modulus

3

2

M N/m

2.1x101.2x1049

24

Poisson' ratio

-

0.45

0.35

0.3

0.3

Dry density

kN/m3

20

20

18

17

Saturated density

kN/m3

-

22

20

18

2

-

30

20

0

CohesionkN/m

Friction angle

Dgree

-

43

40

35

Dilatation angle
Coefficient of
Hortizontal permeability
Coefficient of
Vertical permeability

Degree

-

13

14

5

-

1

1

1

-

1

1

1

kx

-

ky

-

In this study, the properties of backfilling materials i.e. LSS and backfilling soil used
for the analysis model in Plaxis were adopted from the previous researcha- Properties of LSS
The original material was Vinhphuc clay taken from a construction site in Hanoi city.
The soil is classified into low liquid limit clay. Geoset 10 made by Taiheiyo Cement Co.
was used as cement stabilizer.
Based on results of flow and bleeding tests and unconfined compression tests on
samples with curing at 28 days, the content of cement stabilizer was assigned to be 200kg/m3 and the target slurry density of LSS was 1.350 g/cm3.
The initial Young’s modulus of LSS, E0 = 58.8 MN/m2 in case of confining pressureof 49 kPa, unit weight,  = 14.0 kN/m3 and shear modulus, G = 197.2 MN/m2 were set as
the basic properties of LSS. The damping ratio of LSS is assumed as 10 %.
b- Properties of backfilling soil

Figure 6.4 Finite element model in Plaxis84CHAPTER 6 REDUCTION OF VEHICLE-INDUCED VIBRATION USING
LIQUEFIED TABILIZED SOIL

Table 6.4 Physical properties of backfilling materials

Because there are not much investigation results on stiffness of the backfilling soil,
the investigation results on backfilling soil (decomposed granite soil, which is “Masado”)
in Daikai station, which suffered from the Southern Hyogo prefecture earthquake in 1995,
were used as the soil parameters. N value and unit weight,  were set at 10 and 17.0 kN/m3,
respectively. Shear modulus, G = 51.531 MN/m2 was estimated from N value inaccordance with Railway Design Standard15). The damping ratio of this material was
assumed as 4 %. The physical properties of two backfilling materials are shown in Table
6.4.
3- Finite element model
The finite element model (FEM) is plotted in Figure 6.4. The FEM is divided by twoparts. The first part is a domain including wave source, i.e., road and soil layers. The
second part consist of the building frame elements16).
Eight analyzed points on the ground surface A, B, C, D, E, F, G, H with distance of 0,
15, 17.583, 20.166, 22.749, 25.332, 27.914, 30.5m respectively from origin of coordinate(road center line on the ground surface) are shown in Figure 6.4.
4- Numerical model in Plaxis
In this study, a 2D model of road, building, surrounding soil and cyclic loading ofvehicles on the road with the use of Plaxis V8.6 finite element software is introduced inorder to evaluate vibration propagation due to passing of vehicles to the ground surface.
In the model, 15-node triangular elements were used infinite element mesh. For
determining the optimum size of element in order to get reasonable precise result in aminimized time, four different meshing patterns were analyzed and the result of analysis
with very fine and fine meshing were very close to each other, therefore, fine meshingpattern were chosen as Figure 6.4.
The analysis is performed to determine responses of the backfilling area and thebuilding due to applied vehicle loading. Therefore, the building frame is supported to be
subjected to static loading of usual dwelling, which are no considered in this analysis.
85

CHAPTER 6 REDUCTION OF VEHICLE-INDUCED VIBRATION USING
LIQUEFIED TABILIZED SOIL

6.3

RESULTS AND DISCUSSION

Horizontal acceleration (m/s2)

Vertical acceleration (m/s2)

10Case 1Case 2

5

0

-5

0

2

4

6

8

10

Elapsed time (s)Case 1Case 2

5

0

-5

-10

Figure 6.5 Vertical acceleration at point E
for load amplitude =400 kN/m, f = 10 Hz

-15

0

2

4

6

8

10

Elapsed time (s)Figure 6.6 Horizontal acceleration at point E
for load amplitude =400 kN/m, f = 10 Hz

Case 1Case 2

15
10

10

5

Horizontal acceleration (m/s2)

Vertical acceleration (m/s2)

20

0
-5
-10
-15
-20
-25
0

2

4

6

8

10

Case 1Case 2

5

0

-5

-10

Elapsed time (s)0Figure 6.7 Vertical acceleration at point H
for load amplitude =400 kN/m, f = 10 Hz

2

4

6

8

10

Elapsed time (s)Figure 6.8 Horizontal acceleration at point H
for load amplitude =400 kN/m, f = 10 Hz

7

E

6

94
A

Maximum vibration level (VdB)

Maxinmum velocity (mm/s)

D
B C

A

5

F
4

H

Case 1 (Backfilling soil)
Case 2 (LSS)

G

3
0

5

10

15

20

25

30

35

Distance (m)Figure 6.9 Distance and maximum velocity

B
93

92

C

D
E

91

F
90

89

Case 1 (Backfilling soil)
Case 2 (LSS)

G
H

0

5

10

15

20

25

30

35

Distance (m)Figure 6.10 Distance and maximum vibration
level

86

CHAPTER 6 REDUCTION OF VEHICLE-INDUCED VIBRATION USING
LIQUEFIED TABILIZED SOIL

6.3.1 Vibration acceleration in Case 1 and Case 2
In this study, the effect of LSS for reduction of vibration under cyclic loading ofvehicles are evaluated. Therefore, the acceleration is described on points E and H to
determine responses of backfilling materials due to cyclic loading. Figure 6.5 showsgraph of vertical vibration acceleration at point E for both cases using the backfillingmaterial of backfilling soil (Case 1) and LSS (Case 2), respectively. It can be seen that
amplitude of the vertical vibration acceleration at point E in Case 2 is significantly lower
than that in Case 1. One of the most important reasons for this difference in the amplitude
between Case 1 and Case 2 is the stiffness of which LSS is much larger than backfillingsoil. Moreover, it can be seen observed that vertical vibration acceleration in Case 2 isdamped more quickly than that in Case 1.
The horizontal vibration time histories at point E for Case 1 and Case 2 are shown in
Figure 6.6. The figure indicates a considerable reduction in the acceleration amplitudes
that achieve about 50 % for LSS.
In Figure 6.7, the time histories of the vertical acceleration at point H are described.
Point H is boundary point between the backfilling area and the building. Analysis ofvibration at point H play an important role not only for the backfilling area but also forthe building. Therefore, effects of reduction of backfilling materials are considered. In the
figure, reduction of the case of backfilling soil is compared with LSS. Although there are
only little differences in the vertical vibration accelerations in two cases, the results show
the reduction of LSS more useful than backfilling soil.
Figure 6.8 shows the horizontal acceleration time histories at point H. It can be noticed
that the acceleration amplitudes in the case of LSS are larger than amplitudes in the caseof backfilling soil.
6.3.2

Relationship between distance maximum vibration velocity and level

From eight analyzed points on the ground surface from A to H in Figure 6.4, it can be
see that ground conditions at points AD are the same for Case1 and Case 2. Therefore,
the level of vibration and velocity at these points are the same for both cases. In this study,level of vibration and velocity at points EH are analyzed.
Figure 6.9 shows relationship between distance and maximum vibration velocity withvehicle speed of 60 km/h. Although amplitude of the vibration velocity in two cases is87

CHAPTER 6 REDUCTION OF VEHICLE-INDUCED VIBRATION USING
LIQUEFIED TABILIZED SOIL

notable difference, amplitude of the vibration velocity in Case 1 is slightly larger than thatin Case 2.
The relationship between distance and maximum vibration level is shown in Figure
6.10. It can be seen that the level of vibration rapidly decreases with distance from thecenter of road for both cases. Moreover, in the backfilling area, at each point, the level ofvibration in Case 2 is lower than that in Case 1. According to the figures, the effect of
LSS on vibration reduction can be observed apparently.
6.4

CONCLUSIONSThis study was focused on the utilization of backfilling soil and LSS as backfillingmaterial, the reducing effect of ground vibration was discussed. The ground vibration
properties were investigated by using the numerical analysis. The model of vehicle bodyhas been improved which is modeled as a system of two degree of freedoms (2-DOFs)
with consideration of primary and secondary suspension elements established in previous
study. The result of the model in term of the load time history can be input data fornumerical model in solution of the road-soil interaction problem and then prediction ofvehicle-induced ground vibration. Based on the analysis results, the conclusions werewithdrawn as follows:
1) As compared with backfilling soil, LSS indicated significantly better reducing effectof ground vibration induced by cyclic loading of vehicles on road due to its larger
stiffness.
2) The analysis results also indicated that the level at the points close to the center ofroad on the ground surface which is strongest impacted from the vehicle-induced
vibration in case of using LSS is lower than that of using backfilling soil.
It is considered that LSS had an effective potential as countermeasure against vehicleinduced vibration on the road. This property was pointed out as a new advantage of LSS.

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., & Murata, O.: Strength anddeformation properties of fibered material mixed in liquefied stabilized soil obtained
from uniaxial compression test, Proc. of the 36th Japan National Conference on
88

CHAPTER 6 REDUCTION OF VEHICLE-INDUCED VIBRATION USING
LIQUEFIED TABILIZED SOIL

Geotechnical Engineering, pp.635-636, 2002 (in Japanese).
Kohata, Y., & 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, pp.721-722, 2004 (in Japanese).
Kohata, Y.: Mechanical property of liquefied stabilized soil and future issues, Doboku
Gakkai Ronbunshuu, F, Vol.62, No.4, pp.618-627, 2006 (in Japanese).
Kohata, Y., Ichikawa, M., Nguyen, C. Gia., & Kato, Y.: Study of damage characteristics
of liquefied stabilized soil mixed with fibered material due to triaxial shearing,
Geosynthetics Engineering Journal, Vol.22, pp.55-62, 2007 (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 atlaboratory and field, Geosynthetic Engineering Journal, Vol.29, pp.33-40, 2014.
Carl E. H., David A. T., Lance D. M.: Transit noise and vibration impact assessment, U.S.
Department of Transportation Federal Transit Administration-Office of Planning andEnvironment 1200 New Jersey Avenue, S.E. Washington, DC 20590, 2006.
SP 23-105.: Estimation of vibration in design, construction and operation of underground,
Code of practice for design and construction, Russian Metro Standard, 2004.
Kurbatskii, G. H.: Measurement of vibrations, Moscow State University of Railway
Engineering, 2008.
QCVN 27:2010/BTNMT.: National Technical Regulation on Vibration, Ministry of
Natural Resources and Environment of Vietnam, 2010 (in Vietnamese).
Tokita, Y.: Vibration Pollution Problems in Japan, Proceedings Inter-Noise ‘75, Tohoku
university, Sendai 980, Japan, pp.465-472, 1975.
Duong, H. Q., Kohata, Y., Nguyen Q. D.: Evaluation on Mitigation of Train-induced
Vibration as Using LSS for Backfilling Ground of Cut and Cover Tunnel by FEM, the50th Japan National Conference on Geotechnical Engineering, pp.2411-2412, 2015.
Das, B. M.: Principles of soil cyclic, PWS-KENT, publishing company, USA, 1995.
TCXDVN.: Design of structure for earthquake resistance, construction standard ofVietnam, p.1, regulations, earthquake impact with building structure, 2006 (inVietnamese).
Railway Technical Research Institute.: Explanation for railway structure and design
standards, 1999.

89

CHAPTER 6 REDUCTION OF VEHICLE-INDUCED VIBRATION USING
LIQUEFIED TABILIZED SOIL

Rao, SS.: The Finite Element Methods in Engineering, Second Edition, Pergamon
Press, New York, 1989.
Lin J.H.: Simulation of cyclic vehicle load on road pavement, Vibroengineering
PROCEDIA, Vol. 5, 2015, p.p 503-508, 2015.
LaBarre R. P., Forbes R. T., Andrew S.: The measurement and analysis of road surface
roughness. Motor Industry Research Association, Report No. 5/1970, Nuneaton,
England, 1970.
Lin J. H.: Variations in cyclic vehicle load on road pavement, International Journal ofPavement Engineering, Vol. 15, p. 558-563, 2014.
Hamdy F., Ahmed M. H.: 2D plaxis finite element modeling of asphalt- concrete pavement
reinforced with geogrid. Journal of Engineering Sciences, Vol. 42 No. 6, pp. 1336 –
1348, 2014.
Agostinacchio M., Ciampa D., Olita S.: The vibrations induced by surface irregularities inroad pavements – a Matlab® approach, DOI 10.1007/s12544-013-0127-8, 2014.
ISO 8608: Mechanical vibration, road surface profiles- Reporting of Measured Data,
2016.

90

Chapter 7

CONCLUSIONS AND RECOMMENDATIONS

7.1

SUMMARY OF INVESTIGATIONS

The purpose of this study is to promote the use of Liquefied Stabilized Soil (LSS) asa backfilling material for construction projects in Hanoi city. As a central part of thisstudy, experimental and analysis works were developed to investigate more advantagesof Liquefied Stabilized Soil (LSS) and LSS mixed with fiber material.
In the experimental works, there are suggestions that LSS can be decreased the slurry
density to reduce vertical earth pressure, however, the study on strength and deformation
properties of the LSS decreased a slurry density has not been investigated. Therefore, twodensities of slurry were made including 1.280 g/cm3 (Df= 100 %) and 1.216 g/cm3 (Df
= 95 %). The triaxial compressive property of LSS decreased slurry density wasinvestigated. The model ground was built with LSS mixed with fiber material amount of
0, 10 kg/m3 (Pc-0, 10), respectively into four pits in the campus. In parallel, the specimensof the same batch were also molded and cured in the laboratory. The specimens wereprepared by trimming LSS retrieved from the model ground (field LSS) and cured
laboratory (laboratory LSS) at the same curing time of 28 and 56 days. A series of CUB
tests were carried out under the conditions at a constant strain rate of 0.054%/min and theeffective confining pressure of 98 kPa. Testing processes had been performed for twotime periods in 2016 and 2017, respectively. The experimental results obtained were also
compared and analyzed. The influences of slurry density on triaxial compressive
properties for LSS and LSS reinforced with fiber material was discussed.
After experimental works, the analysis works were performed, the methods for
estimation of soil dynamic parameters, the methods for determination of Vehicle-induced
vibration, and analysis model to estimate vehicle-induced vibration as using LSS. In orderto determine dynamic parameters of soil, geotechnical approaches were presented. Basedon current conditions, the methods to evaluate the dynamic parameters were proposed. In
addition, vehicle-induced vibration from the road in Hanoi city was studied. Analyticaland numerical approaches were presented to determine cyclic loading caused by vehicles.
91

CHAPTER 7

CONCLUSIONS AND RECOMMENDATIONS

After that, a numerical investigation of LSS to be backfilled in order to reduce thebuilding vibrations due to passing vehicles in traffic is discussed. Particularly, finite
element (FE) model of a two-dimensional soil-structure system containing the crosssection of a route, the foundation ground, the backfilling LSS and a nearby building
including eight floors and one basement is considered. The effects of LSS on the structure
response are investigated. Based on the analysis results, the effects of backfilling materialon the reduction of vibration caused by passing vehicles in traffic was evaluated.
7.2

SUMMARY OF FINDINGS AND CONCLUSIONS

The relationship between deviator stress q (=σ- σ3) and axial strain εa has indicatedthat when the slurry density is slightly decreased from the appropriate slurry density
obtained from the standard mix proportion design figure, it is considered that the qmax
decreased remarkably. In addition, it is found that the local damage caused by shearing
even in the case of low slurry density is reduced by the effect of reinforcement on thefiber material. Moreover, by the addition of the fiber material, the brittle property of LSS
cured in the field after the peak is improved. In addition, the deformation properties
obtained were also pointed out that the Etan/E0 ~ q/qmax relation of both LSS cured in thelaboratory and at field shows a relatively similar tendency. It seems that the nonlinearityof q~ε relation increase as decreasing slurry density. The experimental results show theinfluence of slurry density on the degree of damage caused by shear is large and it seems
that the degree of damage tends to be reduced by the addition of fiber material. However,
it is suggested that the application of LSS mixed with fiber material as a backfillingmaterial to construction sites enables to create a ground with the improved ductile
characteristic, although it needs to conduct more study.
At present, The Cone Penetration Test (CPT) is suggested using in Vietnam in orderto estimate soil dynamic parameters. Because the estimation of the soil dynamic
parameters based on CPT data with low cost is feasible to apply in the practical condition
in Vietnam. In addition, modeling procedure of dynamic loading with a single-axle
quarter-truck vehicle with 2- degree of freedoms (DOFs) was performed. The numericalresult with high reliability can be input data for ground-borne vibration analysis model.
On the other hand, the use of Plaxis, a program being popular in Vietnam, has brought
reliable results. From Plaxis program, the evaluation on vehicle-induced vibration as
using LSS for backfill ground has indicated that as compared with backfilling soil, LSS
indicated significantly better-reducing effect of ground vibration induced by cyclic
92CHAPTER 7

CONCLUSIONS AND RECOMMENDATIONS

loading of vehicles on road due to its larger stiffness, and the level at the points close to
the center of road on the ground surface which is strongest impacted by the vehicleinduced vibration in case of using LSS is lower than that of using backfilling soil.
Therefore, it is considered that LSS had an effective potential as a countermeasure against
vehicle-induced vibration on the road. This property was pointed out as a new advantageof LSS.
7.3

RECOMMENDATIONS FOR FUTURE RESEARCH

The experimental works under cyclic loading have not been investigated. Therefore,
the triaxial tests under cyclic loading condition simulated as traffic loading need to be
performed on specimens retrieved from model ground backfilled by fibered LSS. Then,a rational construction method on practical fieldwork will be proposed.
In order to apply LSS and LSS reinforced with fiber material in Vietnam, the triaxial
compressive properties for LSS and LSS reinforced with fiber material need to be
determined under longtime curing.
The effect of the temperature on properties of field LSS during curing time should bedetermined. On the other hand, dynamic parameters of LSS mixed with fiber material
should be investigated, and then, reduction of vehicle-induced vibration should beestablished by the numerical model.

93