STUDY ON THE SINGLE AND GROUP OF SOIL CEMENT PILE FOR HIGH RISE BUILDING

MINISTRY OF EDUCATION AND TRAINING

DANANG UNIVERSITY
----------------------

DO HUU DAO

STUDY ON THE SINGLE AND GROUP OF SOIL
CEMENT PILE FOR HIGH RISE BUILDING
MAJOR

: MECHANICAL ENGINEERING

CODE

: 62.52.01.01

SUMMARY OF DOCTORAL DISSERTATION

Da Nang – 2015


The doctoral dissertation has finished at
Danang University of Technogogy - Da nang University

Science Instructor:
1. Prof.Dr. Nguyen Truong Tien
2. AProf. Dr. Phan Cao Tho

Reviewer 1: Prof.Dr. Trinh Minh Thu
Reviewer 2: Prof.Dr. Do Nhu Trang

Reviewer 3: Dr. Tran Dinh Quang

Da nang - 2015


1

INTRODUTION
1. Study Issues
Soil cement pile is the product of the techniques of mixing cement in
local soil – by deep mixing method, processing of forming the pile after the
setting of cement. The advantages of soil cement pile are reducing
settlement for construction, reinforcing soft soil, increasing load bearing
capacity for work foundation, highly mechanized construction, rapidly
progressing construction, reducing costs by using local soil, reducing waste
of soil and environment pollution.
For soil cement piles constructed in sandy soil, the unconfined
compressive strength is from (3.010)MPa, so it can be applied as pile
foundation bearing load construction of high rise buildings in the permitted
conditions. However, the stiffness of the SCP is small so that the conduct
between the pile - soil, pile – soil - pile in the group will be different from
the usual kind of concrete pile. The main focuses, then, are the strength
properties of materials sand-cement, load transfer mechanism, mobilization
of side friction, tip resistance of single pile, the pile in the groups and
determining group factor, and applying in the design stage for high-rise
buildings. This is the foundation of my dissertation: "Study on the single
and group of soil cement piles for high-rise building."
2. The purpose of the dissertation
- Develop a database of properties of the material strength of soilcement piles by wet mixing method for some types of soil: sand, sandyclay, aims to create soil cement pile with high strength, bearing load for
foundation construction.

- Study of the load transmission, the mobilization of side friction and tip
resistance of single pile and group soil cement pile from full scale model test, as
a basis for evaluation of soil cement pile for bearing load applications.
- Analyze of group soil cement pile by numerical model and building
correlation about group factor for soil cement pile.


2
3. Study subjects
Soil cement pile by wet mixing method, Japanese technology,
constructing in sandy and sandy – clay, area of Quang Nam - Da Nang city.
4. Research Content
- Overview of the mechanical properties of materials and the impact of
the pile elements SCP, the problem of load bearing capacity of single pile
and pile group, brief survey of regional geological characteristics of Da
Nang - Quang Nam.
- Study on the strength characteristics of the material pile SCP by
experiments in the laboratory and the field.
- Experiment on the full scale model test for single and group soil
cement pile by static load compression with strain gages and analyze the
results.
- Numerize simulation by Finite Element Method to verify the model
test and practical projects, developing simulation to construct correlation
group factor for group soil cement pile.
- Develop procedures calculations and computer program software
SCPile to automate calculation and design for soil cement pile foundation.
5. Study Methodology
- Exprimental methods in the laboratory and combine the field apply to
the strength characteristics of the material soil cement piles.
- Experimental methods by full sacle model test with strain gages for

single and group soil cement piles.
- Numerical simulation method by Plaxis 3D Foundation and
development for various SCpile groups based on soil model Mohr - Coulomb.
6. Scope of Study
- Soil cement pile by wet method, for sandy soils, sandy – clay on area
of Quang Nam-Da Nang city, not use additives.
- The dissertation focuses on analyzing the soil cement pile bearing
vertical load.


3
- Scope of applied: the high-rise building to level II (lower 19 floors)
on sandy areas Danang and other area with similar geological.
7. New contributions of the dissertation
- Developing a database of correlated about unconfined compressive
strength and bending strength of material SCP for 04 soil types.
- Analyzing the load transmission and distribution side friction, tip
resistance for single pile and pile group from full scale model test.
Determine the coefficient of side and tip resistance by formulations
Meyerhof to apply calculation bearing capacity of single SCP.
- Analyzing the mobilizing resistance of piles in groups, determination
of group factor and recommended calculating load capacity for SCP
foundation by teamwork "Group".
- Developing graphs and equations determining goup factor of the
group SCP according to the number of pile with different distances from the
3D numerical simulation.
- Developing the procedures of calculation and the software program of
SCPile automated calculation, design of SCP foundation and applied to one
real projects.
8. The structure of the dissertation

In addition to the introduction, table of contents, list of references,
scientific published, drawings, tables, appendices, thesis consists of 130
pages is organized in five chapters:
Chapter 1: Overview of the soil cement pile
Chapter 2: Some results of experimental studies on the characteristics of
the strength soil cement pile
Chapter 3: Study the the single and group soil cement piles by full scale
model test
Chapter 4: Numerical simulation and construction of the correlation
groups factor for soil cement pile
Chapter 5: Application of soil cement piles for high rise building.


4
CHAPTER 1
OVERVIEW OF SOIL CEMENT PILE
1.1. Introduction
1.1.1. Process of establishment and development of SCPile
The soil cement pile originally is researched and applied in Sweden and
Japan in the 1960s, and then now gained popularity in the worldwide
market. Two construction methods has usually been used are the wet and
dry mixing methods. Since 1980s, The soil cement pile (SCPile) in Vietnam
has frequently been applied to the improvement of soft soil, they also have
used for building.
1.1.2. Applications of soil cement pile
The applications of SCPile in Sweden, Japan and other countries has
commonly been used to the improvement of soft ground. In Vietnam, the
research and application of SCPile in two principle directions: piles to the
improvement of soft soil and piles bearing, including application of SCPile
bearing in high buildings in geology condition is sand could increase

efficiency, reduce costs.
1.1.3. Deep mixing methods of soil cement pile
In the deep mixing method, soft soil is stabilized in situ by two major
techniques: the dry method of deep mixing is used for soft soil with high
humidity from (60  200)% and the wet method of deep mixing is applied to
soil has water content smaller. Experiments in the thesis by the wet method.
1.1.4. A number of domestic and foreign research on SCPile
Includes two major groups: Group studies about strength characteristic
of piles by laboratory experiments, field studies and other, studying
mechanical bearing load of sigle and SCPile group.
Most studies have focused for the purpose use cement to improve soft
clays, organic soils, soil swellings. The thesis going to continue to develop
on the basis of this approachs with SCPile application for bearing of the
building foundation on sandy soil.


5
1.2. Strength characteristics of SCPile
For SCPile bearing for works, characteristics that have affect the
significant important of which is: unconfined compressive strength, qu (in
the room and field), bending strength qb, elastic modulus E50.
1.3. Basic calculations for single and SCPile group
1.3.1. Load-bearing capacity of single pile
Includes load bearing capacity follow the material of pile and the
ground, with the methods of calculation of Broms (1984) [1], Japan [37],
Jiehan (2011) [56]. These methods are based on the application of the
SCPile to improvement of soft clay ground. Some calculations based on
formulas from SPT testing results such as Meyerhof and Japan, however,
the coefficients of the skin resistance and the tip resistance are inappropriate
and should be determined from the results of experiments.

1.3.2. Calculation of pile groups SCPile
- Ultimate bearing capacity of SCPile group: usually be applied
according to viewpoint of pile foundation work as style "Block" of Bergado
by Equation (1.9) and (1:11), the method of Broms by Equation (1:12).
Method of Bouassida and Porbaha by Equation (1:13) and (1:14) has more
advance, but still the concept equivalent background. For SCPile group, this
position is not reasonable. So, need to determine a suitable method for
practical applications.
- The effect of pile groups: be assessed through the efficency pile
groups. The methods according to Feld's (Equation 1:15), Terzaghi and
Peck (Equation 1:16), Convese-Labarre (Equation 1:17), Coduto (Equation
1:18) and Seyed & Bakeer (Equation 1:20). In this follow-Labarre Convese
is applied more widely. However these methods are applied to hard piles.
For SCPiles which have smaller stiffness and behavior between pile - soil,
pile - soil - pile have more difference. Thus, the effect of pile groups is need
to research additionally and determination of the efficiency pile groups.


6
1.4. Geological features in Da Nang - Quang Nam and application
prospects SCPiles for high rise buildings
The research and the survey’s results show that the geological
characteristics of Da Nang city is sandy soil which is distributed over the surface
with the thickness from 13m to 18m. This sand is reasonable to use the solution
of SCPile for high buildings to level II (19 floors), contributing to decrease costs.

Figure 1.15. A typical geological section of Danang city [4]
1.5. Some problems exist in study on SCPile for high rise buildings
1.5.1. Some problems exist
Material: The study material for soil-cement pile concentrated for the

purpose of handling the soft clay soil is not suitable for applications such as
a SCPile solution for bearing load.
Bearing capacity of piles and pile groups: methods for calculating the
bearing capacity of the pile and pile groups follow material and ground are
based on shear strength of soft soil around piles and pile groups. This
calculation does not suitable with the opinion SCPile work as piles.
1.5.2. The task of the dissertation
This dissertation develops on the strength of SCPile material for
specific types of soil which can be applied for constructing bearing piles.
Researching on the working process of single pile and SCPile group
through full scale model and 3D simulation. At the same time, establishing a
calculation process to initially applied in the calculation, the practical design.


7
CHAPTER 2
SOME RESEARCH RESULTS OF STRENGTH
CHARACTERISTICS FOR SOIL CEMENT PILE’S MATERIAL
2.1. Introdution
The working process of the SCPile as the transmission of SCPile,
mobilizing resistance, pile group effects, horizontal bearing capacity which
will depend on two properties: unconfined compressive strength qu and
bending strength of pile qb. Therefore, before analyzing the working of
single pile and pile group is need to have the results of research on the
characteristics and relative strength. This chapter presents the results of
laboratory experiments on the properties of the material strength of SCPile.
2.2. The scope of sampling and testing of soil, cement
Scope of soil sampling: The laboratory will focus for 04 soil groups
include: group No.1: clayey sand soil, group No.2: fine-grained sand, group
No.3: small-grained sand and group No.4: coarse-grained sand.

Grain size distribution

100

80
70
60
50
40
No1

30

No2

20

No3

10

Perecent finer by weight(%)

90

No4

0.001

0.01

0.1

1
Grain size (mm)

10

0
100

Figure 2.2. Grain size distribution of 04 soil types
The laboratory experiments about properties of soil is examined
through XRF machine to determine the amount of oxides in the soil.
Cement and water: The chemical testing of the two types of cement
PCB30 and PCB40 were also analyzed. Use clean water to mix the sample.


8

2.3. Method of testing and calculation the result
Soil

ax=150kg/m3

ax=200kg/m3

qu, qb (7days)

Cement

ax=200kg/m3

qu, qb (14days)

ax=300kg/m3

qu, qb (28days)

ax=350kg/m3

qu, qb (56days)

Correlation

%qu, qb -ax-t

qu, qb--t

qu, qb - ax - t

E50 - qu

qu - qb

Figure 2.4. The laboratory experiments programme and analysis
The mixing, casting and curing samples and calculating the results by
(TCVN9403: 2012)[20]. Compression and bending samples on automatic
that can produce chart of stress - strain by Trapezium software.
2.4. Results of experimental studies

2.4.1. Results of compressive testing
Some charts show of the relationship between qu-ax-t, và E50 - qu - ax
12

1400

y = 124.84x
R2 = 1.00

y = 1.08Ln(x) + 5.97

1200

10

1000
y = 1.18Ln(x) + 2.30

6

y = 1.05Ln(x) + 2.43

4

y = 1.07Ln(x) + 0.46

150kg/m3

E 50 (N/mm2)

qu(N/mm2)

y = 1.19Ln(x) + 3.45

8

y = 113.40x
R2 = 0.99

800

TH1

600

y = 98.58x

400

200kg/m3

2

y = 0.67Ln(x) + 0.22

250kg/m3
300kg/m3

0
0

10

20

30

Curing time (days)

40

50

350kg/m3

60

Average

Figure 2.16. Relationship qu-ax-t for
fourth soil type

TH2

R2 = 1.00

TH3

y = 90.66x
2

y = 84.31x R = 0.83
R2 = 1.00

200
0
0

2

4

6
qu(N/mm2)

TH4
TH5

8

10

12

Figure 2.20. Relationship E50 - qu - ax
for fourth soil type


9
Table 2.7. The sum of strength growth qu - t
Soil type

qu7-qu28

qu14-qu28

qu56-qu28

Group No.1

qu7=(0,36÷0,51)qu28

qu14=(0,43÷0,67)qu28

qu56=(1,09÷1,20)qu28

Group No.2

qu7=(0,46÷0,65)qu28

qu14=(0,64÷0,81)qu28

qu56=(1,03÷1,05)qu28

Group No.3

qu7=(0,60÷0,80)qu28

qu14=(0,76÷0,94)qu28

qu56=(1,02÷1,04)qu28

Group No.4

qu7=(0,62÷0,82)qu28

qu21=(0,84÷0,96)qu28

qu56=(1,02÷1,10)qu28

Table 2.8. The relative equation of strength growth qu - t
clayey sand soil
(group 1)
qu=0,52Ln(t)-0,13

fine - grained sand
(group 2)
qu=0,66Ln(t)+0,37

small-grained
sand(group 3)
qu=0,75Ln(t)+2,03

coarse-grained
sand (group 4)
qu=1,05Ln(t)+2,43

Table 2.9. Compare with other results about strength growth qu - t
P.V.An [17]
qu14=(0,43÷0,67)qu28
qu21=0,56qu28

qu56=(1,04÷1,25)qu28

China [17]
qu14=(0,62÷0,8)qu28
qu56=(1,15÷1,46)qu28
qu90=(1,31,8)qu28

Japan [39]
qu7=(0,63÷0,694)qu28
qu21=0,56qu28
qu56=(1,04÷1,25)qu28

Sweden [51]
qu7=0,58qu28
qu14=0,79qu28
qu56=1,208qu28

2.4.2. Results of bending testing
Some graphs show of the relationship between qb-t-ax và qu-qb-ax
4.5

8

y = 0.54Ln(x) + 1.84

4

6

y = 0.43Ln(x) + 1.29

3

y = 0.45Ln(x) + 1.12

2.5

y = 0.52Ln(x) + 0.45

2
1.5

150kg/m3

qb(N/mm2)

qb(N/mm2)

7

y = 0.42Ln(x) + 1.78

3.5

y = 0.35Ln(x) + 0.24

0.5
0
10

20

30

40

Curing time (days)

50

3

250kg/m3

1

300kg/m3

0

350kg/m3

0

4

2

200kg/m3

1

y = 0.65x - 0.03
R2 = 0.96

5

y = 0.29x + 0.00
R2 = 1.00

0

60

2

Average

Figure 2.28. Relationship qb-t-ax for
fourth soil group

4

6
qu(N/mm2)

8

10

Figure 2.29. Relationship qu-qb-ax of
04 soil groups

Table 2.15. The sum of relative qb - qu for soil groups
Soil groups

clayey sand soil
(No1)

fine - grained
sand (No2)

small-grained
sand (No3)

coarse-grained
sand (No4)

qb/qu

0,29÷0,458

0,35÷0,463

0,452÷0,508

0,38÷0,65

Discussion: The relative results between qb and qu have changes less
than the results are found by Professor Terashi who performed on both the

reinforce blinder is combination of cement and lime qb/qu = (0,1÷0,6)[39].


10
2.4.3. Establishment relationship between cement ax and qu
10

y = 8.36Ln(x) - 39.44
R2 = 0.98

No2

qu(N/mm2)

No3

8

y = 54.85x 2. 00
y = 71.84x 1. 21
R2 = 0.98
R2 = 0.99

400

No1

y = 5.13Ln(x) - 23.22
R2 = 0.99

No4

6
y = 2.13Ln(x) - 8.90
R2 = 1.00

4
2

350

y = 67.04x 0.83
R2 = 0.98

300
ax(kg/m3)

12

y = 1.08Ln(x) - 3.79

y = 72.14x 0.68
R2 = 1.00

250
200
150

No1

100

No2
No3

50

R2 = 0.97

0
150

No4

0
200

250

300

350

400

1.5

3.5

ax(kg/m3)

5.5

7.5

9.5

11.5

qu (N/mm2)

Figure 2.30. Relationship qu - ax of 04
soil groups

Figure 2.31. Relationship ax - qu of 04
soil groups

2.4.4. Impact of grain size distribution and chemical properties of soil
12

120

ax=150kg/m3
ax=200kg/m3

10

100

ax=250kg/m3

Percent%

qu(MPa)

ax=300kg/m3

8

ax=350kg/m3

6
4

SiO2

80

Fe2O3

60

Al2O3
SO3

40

K2O
CaO

20

2
0
0.35

Ti2O

0
0.45

0.55

0.65

0.75

0.85

0.95

1

Pd=d>0,25/d>0,1

Figure 2.32b. Impact of grain size rate
Pd to qu (Pd=d>0,25mm/d>0,1mm)

2
3

Type of soil (No)

4

Figure 2.33a. Impact of chemical
constituents of soil to qu

2.4.5. Relationship strength between laboratory and field experiments
Combining experiments on three projects have got rate among quf field
experiments strength quf and the strength of the laboratory experiments qul:
quf = (0,621,5) qul
2.5. Conclusion of chapter 2
Results Chapter 2 has established strength growth equation qu, qb over time
and an amount of cement ax, qu-E50-ax. Determine the ratio of bending
strength qb and qu, build the relationship between an amount of cement ax
and qu and contrary for 04 soil types. At the same time, evaluate the effect
of grain size distribution via coefficient Pd and chemical properties of soil
to soil strength qu, assess relationship between quf field experiments strength
quf and the strength of the laboratory experiments qul.


11
CHAPTER 3
STUDY ON WORKING OF SINGLE AND GROUPS OF SCPILE BY
FULL SCALE MODEL EXPERIMENT
3.1. Introdution
The purpose of the model construction: The construction of full scale
model is to find about the movement of stress - strain, the transmission
mechanism, mobilization of skinl friction, resistance in the top of single pile
and pile group (SCPile). Based on the analysis of experimental results will

determine the bearing capacity factor, efficiency of pile groups and the
percentage distribution of the load capacity of the piles in the group.
Technologies, equipment and standards apply: SCPile by technology of
Japan, wet mixing method. There are devices used to measure the axial
strain are Geokon 4911 and 4200. The standards applied and references:
ISO 4903: 2012, ISO 9393: 2012, ASTM D1143.
3.2. Preparing experiment
Location experiments at the Tuyen Son park area - Da Nang City, the
Geotechnical experimental results are showed on Figure 3.5 and 3.6.
Grain size
contribution
Layer soil

Natural
weight
(kN/m3 )

CPT-qc(MPa)
0

0 20 40 60 8010010 20 30 40 50 16 17 18 19

Sand
Clay-sand,
Plastic Clay Silt

Smooth sand Buûi
Sand
Silt
Silt Sand

12

Depth (m)

Sand

10

0

2

2

4

4

6

6

25 50 75 100

MNN

2

8

0

Sand

Smooth sand
Grey-White

6

CPT-fs(kPa)
0

5 10 15 20 25

8

Depth (m)

0

4

Wd(%)
Wch(%)

8

10

10

12

12

14

14

16

16

Sand
Silt

Clay-sand,
Grey - Green Clay Silt

Sand

14

Figure 3.5. Distribution of physical
properties of soil with depth

Figure 3.6. Result of cone penetration
test CPTu

12
Single SCPile Model
D600, l=7,5M

Pile raft
Concrete 35Mpa
0.00

# ST1: -1.5m

Fine sand

Layer 1: Fine sand
depth : 2m

Layer 2: Clay sand, depth: 2,0m

# ST2: -3.5m

-4.00

Layer 2: Clay sand, depth: 2,0m

# ST2: -3.5m

Stell tube D60

# ST3: -5.5m
Medium sand

Strain gages

Layer: Medium
sand, depth 5,5m
Strain gages

# ST4: -7.3m
SCPile D600

# ST2: -3.5m

# ST3: -5.5m

Layer 3: Medium
sand, depth 5,5m
Strain gages
# ST4: -7.3m
SCPile D600
2200

Pile tip: -7.50

Pile tip: -7.50

Strain gages
Telltale d=22mm

Strain gages
Telltale d=22mm

TP2
S= 1,5D=1200mm

2250

TP3

Steel tube D60
d=1,2mm (A9)

Steel tube D60
d=1,2mm (A9)

TP6
TP7

0

Steel tube D60
d=1,2mm (A9)

Pile tip: -7.50

Strain gages
Telltale d=22mm
0
12

TP5

Steel tube D60 TP1
d=1,2mm (A9)

2200

TP4

50
22 200
1

Steel tube D60
d=1,2mm (A9)

Layer 2: Clay sand, depth: 2,0m

# ST4: -7.3m

SCPile D600
Steel tube D60
d=1,2mm (A9)

# ST1: -1.5m

Stell tube D60

# ST3: -5.5m
Mediunm sand

Stell tube D60

Layer 1: Fine sand
depth : 2m

-4.00

-4.00

Layer 3: Medium
sand, depth 5,5m

+0.25

-2.00

Clay - sand

-2.00

Clay - sand

Clay-sand

+0.25

700

# ST1: -1.5m

Fine sand

Layer 1: Fine sand
depth : 2m
-2.00

Medium sand

Group 05 SCPiles Model
D600, l=7,5M
Pile raft
Concrete 35Mpa
0.00
700

Pile head: +0.2

0.00

Fine sand

Group 03 SCPiles Model
D600, l=7,5M

TP8

TP9
Strain gages
Telltale d=22mm
Steel tube D60
d=1,2mm (A9)

TP10

Figure 3.8. Drawwing of full sacle load tets for sigle and group SCPile

3.3. Establish models and conduct experiments

Some pictures constructing and loading full sacle model test

Table 3.2. Design layout of test equipment for model
No
01
02
03
04
05

Pile
TP4
TP5
TP1
TP2
TP3

Test equipment
ST(01), GKA9 (01)Telltale (01)
GKA9 (01)
Telltale (01), GKA9 (01)
Strain gages (01), Telltale (01)
GKA9 (01)

Number
06
07
08
09
10

Pile
TP6
TP7
TP8
TP9
TP10

Test equipment
ST(01), Telltale (01)
ST(01), Telltale (01)
GKA9 (01)
GKA9 (01)
Telltale (01)

SCPiles have diameter 600mm, length 7.5 m, qutk = 5,5MPa.


13
3.4. Analysis of the experimental results
3.4.1. The basis of analysis transmission and ultimate bearing capacity
3.4.2. Analysis of single pile
3.4.2.1. Analysis transmission for single pile
Load (kN)

-0.5

0

200

400

600

Side friction (kPa)
800 1000 1200
-0.5

-1.5

-2.5

-2.5
Depth (m)

Depth (m)

-1.5

-3.5

20

40

60

80

-3.5

-4.5

-4.5

-5.5

-5.5

-6.5

-6.5

-7.5

-7.5

Figure 3.17. Load distribution on TP5

0

Figure 3.18. Graph distribution side

friction of TP5

3.4.2.2. Analysis ultimate bearing capacity for single pile
0.04

Load P(kN)
0
-5

0.035

0

200

400

600

800

1000

1200
0.025

-15

S/P

Movement S(mm)

y = 0.0007x + 0.0057
R2 = 0.9995

0.03

-10

0.02

y = 0.0007x + 0.005

-20

R2 = 0.9991

0.015

-25
-30

TP4
Davis sion Offset

-35
-40

0.01

TP5

TP4

0.005

De Beer method
Snip method
Ave Sigle SCP

-45

Figure 3.25. Detemination limit
bearing capacity Qu of TP4 and TP5

TP5

0
0

10

20

30

40

50

S(mm)

Figure 3.26. Detemination Qu from Chin
Konder extraplation

Skin resistance of the piles through the soil layer is evaluated via  factor
by method of Bjerrum -Burland, and calculate inversely coefficient of skin
resistance Cs follows Eslami and Fellenius from cone penetration test.


14
Calculate inversely coefficient of skin resistance and tip resistance in
the formula for calculating the bearing capacity for SCPile according
Meyerhof (3.4), the coefficient K1, K2 clearly show a decrease in tip
resistance and a increase the skin resistance of SC pile.

(3.4)

Qu  K 1 .N a  K 2 . N tb . As
Table 3:17. K1 and K2 coefficients for the formula of Meyerhof
Bearing factor
Precast pile
Bored pile
Factor K1 (kPa)
400
120
Factor K2 (kPa)
2,0
1,0

SC pile

100
3,0

3.4.3. Analysis of pile groups
3.4.3.1. Analysis transmission and distribution skin friction of piles in group
Load (kN)
200

400

600

Load (kN)
800

Load (kN)

1000

-0.5 0

200

400

600

800

1000

-0.5

-1.5

-1.5

-2.5

-2.5

-2.5

-3.5

Depth (m)

-1.5

Depth (m)

Depth (m)

-0.5

0

-3.5

-4.5

-4.5

-5.5

-5.5

-5.5

-6.5

-6.5

-6.5

-7.5

-7.5

-7.5

Load distribution TP7-G2

200

400

600

800

1000

-3.5

-4.5

Load distribution TP3-G1

0

Load distribution TP8-G3

Chart sum mobilized side friction and tip resistance for the single pile and pile group
Qf(kN)
0

150

300

450

600

0

750
-10

-20

-20

S(mm)

-30

300

450

600

750

-30

-40

-60

150

S pile tip(mm)

-10

-50

Qr(kN)

0

0

-40

TP5
TP3
TP7
TP8

Figure 3.46. Graph mobilized side friction

-50

-60

TP5
TP3
TP7
TP8

Figure 3.47. Graph mobilized tip resistant


15
Below charts display distribution skin friction along the shaft pile under the
load levels for the piles TP3, TP7, TP8:

Side friction (kPa)
20

40

60

80

-0.5 0

-1.5

-1.5

-1.5

-2.5

-2.5

-2.5

40

60

80

20

40

60

80

-0.5

Depth (m)

-3.5

20

0

-0.5

Depth (m)

Depth (m)

0

Side friction (kPa)

Side friction (kPa)

-3.5

-3.5

-4.5

-4.5

-4.5

-5.5

-5.5

-5.5

-6.5

-6.5

-6.5

-7.5

-7.5

-7.5

Distribution fi TP3-G1

Distribution fi TP7-G2

Distribution fi TP8-G2

Table 3.18. The unit skin resistance fs from experimental results (kPa)
Depth
0-2,0m
2-4,0m
4,0-5,5m
5,5-7,5m

TP5
62,12
26,79
53,25
57,75

TP3
62,02
25,79
51
54

TP7
63,62
24,44
41,25
50,25

TP8
62,99

26,39
49,50
51,00

Table 3.19. The skin resistance and tip resistance of piles (kN)
Resistance
Qf
Qr

TP5
638,17(0%)
582,68 (0%)

TP3
625,5(-1,98%)
290,4(-45,1%)

TP7
535,03(-16.16%)
304,97(-47,66%)

TP8
611,52(-4,17)
228,48(-60,78%)

3.4.3.2. Analysis ultimate bearing capacity of pile
0.07

Load P(kN)

0
0

180

360

540

720

900

0.06

1080

-20
-30
-40
-50
-60

y = 0.0009x + 0.0208
Nhóm G2

0.05

S/P

Movement S(mm)

-10

TP4
TP5
G1
G2
Davission Of f set
De Beer method
Snip method
Ave Single SCP

Figure 3.54. Analysis Qu of piles tets

y = 0.0008x + 0.0116
Nhóm G1

0.04
0.03

y = 0.0007x + 0.0057
Cọc đơn TP5

0.02
y = 0.0007x + 0.005
Cọc đơn TP4

0.01
0

0

10

20

30

40

50

60

S(mm)

Figure 3.55. Analysis Qu by extrapolation


16
Table 3:21. Results of efficiency of pile groups from testing
Efficiency of pile groups  determine from Qu follow methods
Pile groups
De Beer
Snip
Davission
Group G1 (03 piles)
0,685
0,684
0,664

Group G2 (05 piles)
0,608
0,586
0,554

Chin
0,875
0,778

Method Davission is selected to calculate the efficiency of pile groups.
Table 3:22. Comparison groups factor from test result and other formulas
Comparison efficiency of pile groups  with theoretical formulas
Terzaghi ConveseCoduto,
Sayed và
Pile/pilegroup Testing Feld’s & Peck
Labarre
2001
Bakeer
Cọc đơn
1,0
1,0
1,0
1,0
1,0
1,0
G1 (03 cọc)
0,87
0,75
0,69
0,595

0,796
0,664
G2 (05 cọc)
0,80
0,688
0,56
0,455
0,566
0,554

3.5. Propose bearing capacity calculation methods for SCPile group
Calculate the bearing capacity of SCPile group by Terzaghi & Peck: Qug  n1 .n2 .Qu (3.5)
N

H

Qf

Qr

B

(6-9)Cu

Failure surface

Cu

Cu

M

Soil cement pile

H

H

Soil cement pile

q

L

Figure 3.56. Method “Block” by
Bergado, 1994

Figure 3.57. Method “Group” is
proposed SCP

3.6. Conclusion of chapter 3
Building a model experiments using test equipment axial deformation strain
gauges, evaluate the mobilization of skin friction and tip resistance of single
pile and pile group, determination of groups and proposed calculation
scheme SCPiles with perspective pile group working as "group".


17
CHAPTER 4
NUMERICAL SIMULATION AND ESTABLISH RELATIONSHIP

ABOUT EFFICIENCY OF PILE FOR SCPILE
4.1. Purpose and method
SCPile parameters:
kE, D, L
Pile raft size

Soil parameters:
kc, E
Soil model
Mohr - Coulonb

Simulation
Model test

Simulation
Model test project

study for group factor

Single SCP Group SCP Group SCP
TP4
G1
G2

Simulation and analysis
model test 05 project

Group from 4 to 25 SCP
Rate: d/D=1, 1.5, 2, 3, 6, 8

Compare with
model test

Compare with
model test

Analysis P-S correlation
Determine group factor

Simulation case

Figure 4.2. Tree graph of case studies numerical simulation for SCPile
a)

b) Pile raft
3

P
Soil cement pile

12

III

15



II

II

4

14

5x
13

Soil

Soil

II

x

x6

2

11

y

Soil

II-II

x

Soil cement pile

D

I-I Soil cement pile

2
3x



Figure 4.3. Axisymmetry
element 3D

z

D

Soil

x
10

5

z
y

8

4x


L

I

x
1

9

6

L

Soil cement pile

P

d

Figure 4.4. Numerical
simulation 3D for single
and group SCPile


18
4.2. Numerical simulation for testing model

Perform numerical simulation by Plaxis 3D Foundation software follow
FEM for single pile, the G1 and G2 groups. Simulation results for the quite
reasonable results compare with the load test data from the models.
Load P(kN)

Load P(kN)

200

400

600

800

1000

0

1200

200

400

600

800

0

1000

-20
-25
-30
-35

Thí nghiệm TN4

-40

FEM 3D TN4

-40

1000

-40

-50

-50
Thí nghiệm G2
-60

FEM-3D-G1

FEM-3D-G2
Daviss ion Line

Davission Line

-70

-70

Figure 4.9. Graph P-S group
G1

Figure 4.7. Graph P-S single
pile TP4

800

-30

-30

Thí nghiệm G1

-45

600

-20

-20

-60

Davission Line

400

Movement S(mm)

-15

200

-10

-10

-10

Movement S(mm)

Movement S(mm)

0

Load P(kN)

0

0

0

-5

Figure 4.11. Graph P-S
group G2

4.3. Numerical simulation of SCPile for practical projects
3D numerical simulation for single piles and groups of 02, 04, 05 and
07 SCPiles with the different distance of 05 practical projects in Da Nang
and Quang Nam includes: Da Nang KIA Showroom, Office Complex FPT,
low-income apartments in neighborhoods An Trung 2, Hospital of Dien Ban
and Tran Thi Ly bridge. Comparison of P-S curve results for closely with
static compressive testing.
4.4. Simulation of construction correlation coefficient pile group SCP
Simulation of the 06 cases pile group 4, 6, 9, 16, 20 and 25 piles at a
distance d/D=(1, 1.5, 2, 3, 6, 8). Determining efficiency of pile groups,
build relationship of their about for SCPile groups.
1

1

0.9

0.9

y = 1.07x -0.07

0.8
0.7

Group factor 

Group factor 

0.8
Nhóm 4 cọc

0.6

Nhóm 6 cọc

0.5

Nhóm 9 cọc
Nhóm 16 cọc

0.4

0.6

y = 1.06x -0.19

0.5

y = 1.01x -0.26

0.4

y = 0.92x -0.31

0.3

d=1D
d=1.5D
d=2D
d=3D
d=6D
d=8D
Power (d=1D)

0.2

Nhóm 20 cọc

0.3

y = 1.07x -0.11

0.7

0.1
Nhóm 25 cọc

0.2
1

2

3

4

5

6

7

d/D

Figure 4.31. Group factor by d/D of
other pile groups

0
8

3

5

7

9

y = 0.76x -0.34

11 13

15

17 19 21 23

25 27 29

Number of SCPile

Figure 4.32. The graph determination
group factor with number of pile in group


19
According to chart (4.31) allows determination of efficiency of pile
groups for the group from (425) piles with central pile spacing
d=(1,08,0)D. Charts (4.32) show determination of pile groups  relative
with n number of piles in the group and the relative corresponding equation.
4.5. Conclusion of Chapter 4
Using Plaxis 3D Foundation software by finite element method and models
Mohr-Coulomb soil materials simulation model for the experimental results of
05 practical projects. On the basis of a reasonable balance between simulation
and experimental results, conducted simulations for different cases of pile
groups in number and different distances, building maps and math equations
determination for calculation of the SCPile bearing capacity
CHAPTER 5
RESEARCH APPLICATION OF SOIL CEMENT PILE FOR THE
HIGH RISE BUILDING
5.1. Introduction
The content of this chapter is to establish a sequence of SCPile
foundation design calculations condition has not standard. At the same time,
conduct build SCPile software for calculation, design and application
SCPiles for a ptactical project.
5.2. Construction calculations sequence pile SCPile

On the basis of Pile foundation Design standards TCVN 205: 1998,
Standard TCVN 9403: 2012, the results of research in the country, the
world and the results of the thesis. The authors constructed sequence
calculation, design consists of 16 steps for pile SCPile, SCPile test under
the limit state based on assumptions and mechanical diagrams.
5.3. Construction program design calculations SCPile
Sitemap general algorithm of a computer program is based on SCPile
order calculations in Section 5.2 as follows:


20
Input
Checked axila load: Pmax, Pmin
Input data: Soil parameter, SPT, load, pile
and pile raft dimension, material
parameter of concrete and steel)
Calculation: soil, foundation, SCPile

Calculation pile bearing capacity, grout

Checked the block foundation convention

Checked soil bearing capacity, settlement

Checked soft soil layer, time settlement

Checked horizontal load: H n, [H]

Group factor, pile group bearing capacity

Calculation, dsign pile raft

Calculation, design steel for pile raft

Output Exel table, design data

Output

The programming language used to write programs calculate the SCPile soil
cement pile is Visual Basic.net (VB.net). Software for calculations, tests
and import, export from Excel.

Tính toán kết quả

Calculation menu

Formular

Drawing result

Figure 5.3. The interface of the program SCPile - Part calculated


21
5.4. Application of design calculations at building FPT Complex
Application of design calculations at FPT Complex Project with more 1200
piles have D800mm diameter piles, length L=10m. Pile layout distance
between the central piles is d=1,5D=1.2m
1400
20

4
20

12 00

5

0

26 00

3000

6

60
8000
4 800

5200

0

20
3800
00

2400
14

3800 00
00
24
48 00
00 12

00
50

24
48 00
00 12

28

00

0

48

12

0
240

1600
40016
0040
0

48
00

0
4 80

0
2 40
0

B1

A1

00
12
24
00

4802

240

400

2400
7650
4800
2850

B2

0

4800
7 400

4 800
7 400

2000
12N

6000

12
0

2600

2600

6800 3200

3600

6000

6000

3600

0200
120 1
2400
0
240 0
0120
120

00

6800 32 00

68

3600

00
24
2400

24
12 00 00
1200

00

7650

4800

320 0

BH3
4800

12

50

28 50

50

76
50
48

28

28
50

60
1200
12 00 00
600 36

00
30
00
00
66
36

48
00

0
6 00
00
60

0
48
00

7 65

00

50

B3

00
72
00

0
3 60
0
6
60
0

72
00

00
24

00
28

50

50
28

28

0
00 7 65

24

76

520 0

D5

48

00

A2

0

5 200

900 300
48000 900

50

00
12
00
24 00
48

A3
28

1500

3200

240
48000 1200

28

4 80

0

410

12

00

00
24 00
00 48

A4

15 00

1200

0
7 65

00

0

00 50
48 76

600
240

2400
410

50

48

40

00

00
0012
12 00
24

48 00

4800

D4

00

0

BH4

00
76

00

50
48

24

50

0

76

0
48

48

0040
016

600

5200

2400
4800
12 00

B4

00

6000
120
60 02400

0

1200

0

480

00

240

790

360

24
48 00
00 12

B5

48

53

4800

8

24

48 00
0

8996

C

00

4 80

00

400
16 00
40

24

16

48 00

146

0

4800

0
2
4 8040 0
0 1 20

400

1 20

60

1950
12N

0
7 20

0
240 0
160
400

2400
16 00400
400

10800

48

BH7

48 00

600 0

00

00

00

12

00
2 4 00
48

C1

00

00
16

60

0
1 20

48

00

6 00
600

4000

4800

16

36 00

00

1600

4800

7

4800

0

24

0

00 3600

4 80

0
00
36 00 60
0 24

68

BH1

600

4800

00

0

360 0

7400

24

50

6 00

2600

00
00 72
48

00

0

28

600

3600
2400
600

00

600

32

60

3600
2400
600

36

60 36
0
00

1200
12
2400 00

BH6

0

0

38
4 80

0

1 40

2 40

3000

A5

A6
B

Figure 5.6. Layout design soil cement pile of building FPT Complex
5.5. Evaluate technical and economic efficiency
Compare the cost of SCPile with

common types of piles for 06

projects in the area of Da Nang as Figure (5.13)
100

Percent %

C2

0 60 0
3 6040 0
2
0

6 60
0
3 00

30
0

0

8 80

60

0

2 80

36
24 00
00

6 00

6 00

00

12
00

0

0
6 00

60
00 3
66

60

00

0
3 00

0
0
3 60 0
24

00

2 60

0 3 60
24 0
00
60

0

6

20
36

24

60
00

24

0
36
24 00
00
60

00

00

00

30
36
0 0 668
00
6000
0
3 60
0

6 00

14
30

2600

24

32
00

20

16

00

60 36
0 24 00
00
60

6600 3600

80
60
40
20

Bored pile D800
Spun pile D500

0
1

2

3

4

Case project

5

Conc pile

6 350*350
SCPile D800

Figure 5.13. Compare by % the pile cots of 6 project in Danang
5.6. The results of Chapter 5
establish a sequence of SCPile foundation design calculations condition has
not standard. From there it established a general algorithm and detail
algorithm, program development and application SCPile for a real project.


22
CONCLUSIONS - RECOMMENDATIONS
1. The conclusions
The results of the "Study on single and groups of soil cement pile for
high rise buildings", are showed as follow:
- From the results of experimental studies in laboratory about strength
characteristics of the SCPile material for 04 types of feature soils s of
the area Da Nang - Quang Nam, with amount of cement changes
(150350)kg/m3 of natural soil, establish relationships, including: the
strength development qu and qb over time as a function logarit:
clayey sand soil
(group 1)
qu=0,52Ln(t)-0,13
qb=0,25Ln(t)-0,18

fine - grained sand
(group 2)
qu=0,66Ln(t)+0,37
qb=0,33Ln(t)-0,15

small-grained
sand(group 3)
qu=0,75Ln(t)+2,03
qb=0,39Ln(t)+0,8

coarse-grained sand
(group 4)
qu=1,05Ln(t)+2,43
qb=0,45Ln(t)+1,12

The relationship between elastic modulus E50 and unconfined compressive
strength qu about: E50 = (74,0133,3) qu; The relationship between bending
strength qu and qb approximately: qb = (0,290,65)qu; relative strength in
the laboratory qul and field strength quf between quf = (0,621,5)qul.
- Establish the relationship between the amount of cement

ax and

compressive strength qu for 04 soil types in the table below:
clayey sand soil
(No1)
qu=1,08Ln(ax)-3,79

fine - grained sand
(No2)
qu=2,13Ln(ax)-8,9

small-grained
sand(No3)
qu=5,13Ln(ax)-23,22

coarse-grained sand
(No4)
qu=8,36Ln(ax)-39,44

a x  54,5q u2.0

a x  71,84q 1u.21

a x  67,04q u0.83

a x  72 ,14 q u0 .68

- To assess the impact of grain size distribution and amount of SiO2 in soil,
the amount of CaO of cement to the strength properties of the SCPile
material. In particular, the influence of grain size distribution, the thesis
proposed factor Pd=(d>0.25mm)/(d>0.1mm) for the soil to determine qu
relatively with the different amount of cement.
- From the experimental results and the full scale model analysis showed
positive displacement due to mobilization of shaft friction on the pile
SCPile (2022) mm relative with 3.5 percent of single pile diameter


23
and displacement from (3035) mm relative with 5.0 percent of single
pile diameter for pile groups, larger than the notion mobilize shaft
friction of hard piles about 8mm.
- From the experimental model of authors have determined the value of the
coefficient of resistance  (according to the method ) by 0.53 in sandy
clay soil and  = (0,690,77) in sandy soil, this result is consistent with

the calculation of cone penetration testing of Eslami and Fellenius. At the
same time determine the bearing capacity factor applied to the pile
SCPile based on the formula of Meyerhof (1976) to calculate the bearing
capacity of the pile with the coefficients K1 and K2 = 100kPa = 2,5kPa.
- Analysis of the impact of the pile group showed significant declining shaft
friction by effects of pile groups from 1.98% group (group 3 piles) to
4.17% (group 5 piles) while reducing shaft friction of middle pile to
16.16%. At the same time raising the tip resistance of the middle pile
higher than edge piles to 31.6% due to the formation of surface soil
wedge tip pile group.
- Results of determination of pile groups for efficiency of pile groups  =
0.664 for group G1 (03 piles) and  = 0.554 for group G2 (05 piles),
this result is quite closely with the method of Convese Labarre and the
gap from 1.4% to 4.3%. Suggest calculate the load capacity of SCPile
groups in sandy soil by perspective as "Group" by formula of Terzaghi
and Peck, results is higher (1,892,17) times than the opinion of pile
groups as "block" also Bergado proposed calculation of weak ground.
- Results of numerical simulation used Plaxis 3D Foundation software and
Mohr-Coulomb soil model for SCPile single piles and pile groups for
06 practical project show results is quite reasonable with experiments
results. On the basis of a reasonable balance between simulation and