Nghiên cứu ảnh hưởng của lớp xi măng đất gia cố mặt nền đến sức chịu tải ngang của cọc đứng, ứng dụng cho đập trụ đỡ vùng đồng bằng sông cửu long (tt)

MINISTRY OF EDUCATION

MINISTRY OF AGRICULTURE AND

AND TRAINING

RURAL DEVELOPMENT

VIETNAM ACADEMY FOR WATER RESOURCES
&

TRAN MINH THAI

RESEARCH THE EFFECT OF SURFACE SOIL CEMENT
REINFORCEMENT LAYER ON THE LATERAL
BEARING CAPACITY OF VERTICAL PILES,
APPLIED TO PILLAR DAM IN THE MEKONG DELTA
Speciality: Hydraulic engineering
Code No: 9.58.02.02
SUMMARY OF TECHNICAL DOCTORAL DISSERTATION

Hanoi 2020


The dissertion was completed at:
VIETNAM ACADEMY FOR WATER RESOURCES

Supervisor:
- Prof. Dr. Nguyen Vu Viet
- Prof. Dr. Tran Dinh Hoa

Reviewer 1:
Reviewer 2:
Reviewer 3:

The dissertation is going to be presented to academy evaluation
committee, which is held at Vietnam Academy for Water
resources, address: 71 Tay Son Street, Dong Da, Ha Noi.
In …………, 2020 at …..

The dissertation can be found at:
- National library in Viet Nam;
- Library of Viet Nam Academy for Water Resources.


1

INTRODUTION
1. The urgency of the Subject
Vietnam is a country which has a long coastline and many large rivers
flowing into the sea stretching from the North to the South. In recent years, the
harshness of nature has become more evident, such as climate change, rising sea
levels, greater storms and floods, and the shortage of fresh water which has
greatly affected life and socio-economic development of the country. The Mekong
Delta is a region with great potential, hold an important role in socio-economic
development and is a key in the national food security strategy.
The big policy of Government is to continue researching and investing in
constructing sea dykes, regulating estuarine areas in tidal areas in order to prevent
and mitigate natural disasters as well as protect economic people and livelihoods,
contribute to the development of the country
The current water control works, the Pillar dam is becoming more and more

widely used, becoming a scientific solution to gradually replace traditional works,
especially reflected in the large hydraulic works which is contructed in coastal
estuaries. In order to further improve the efficiency of technology application, it is
necessary to continue researching and perfecting both theory and experiment. on
unexplained issues. For Pillar dam, it is often suffer from great horizontal loads.
In addition to the solution of oblique piles, the reinforcement of the foundation
surface layer will be able to increase the lateral bearing capacity of the pile
foundation. In order to determine the appropriate size for the reinforcement layer
and evaluate how the impact on the lateral bearing capacity of the pile foundation
of the supporting pier has so far been unresolved. Therefore, the the Subject is
urgent and practical.
2. Research purposes
- In oder to a scientific basis, perfecting the theory in calculating and the
design of Pillar Dam.
- Proposing the form and structure of the surface reinforcement layer to
increase the lateral bearing capacity for foundation pile of Pillar Dam in the
Mekong Delta.
3. Research Methods
Method of theoretical research:
- Research and analyze relevant technical information published through
documents such as books, newspapers, design standards ... Domestic and Foreign.
- Using mathematical model to research and analyze the influence of the
reinforcement layer on the lateral bearing capacity of single piles, thereby
selecting the reasonable size of the surface reinforcement layer corresponding to
the types of piles.
Experimental research methods:
Experimenting physical models, measuring, evaluating lateral bearing
capacity of piles in cases of working on natural soft ground and the ground after

2

surface layer reinforcement. On that basis, compared with the established
theoretical research method, there was a conclusion about the method of
calculating the lateral bearing capacity of the pile, which is the basis for the
stability of the pile foundation of the Pillar Dam in Mekong Delta;
Professional solution:
Organize scientific conferences and critical review meetings, including
scientists who have in-depth knowledge of the research area of the PhD student, to
comment, evaluate and critique the research results.
4. Research object
The horizontal axial strength of single vertical piles in case of reinforcing the
surface layer of pile foundation side at the tip of pile head of the Mekong Delta.
5. Research scope
- Structure: Vertical single pile in the foundation of Pillar Dam on soft
ground in the Mekong Delta.
- Pile material: reinforced concrete piles
- Reinforcing: Reinforcing the foundation surface layer of the top of pile with
soil cement piles which is used deep mixing technology

6. Scientific and practical significance of the thesis
- The dissertation has established a scientific basis for calculating the
reinforcement of pile foundation surface (new structure, natural ground combined
with cement by deep mixing method), which increases the horizontal resistance of
the foundation of the Pillar dam in Mekong Delta, where the soft ground
characteristics are detrimental to construction.
- The research results of the thesis have been applied in pile foundation
design and to complete the theory of Pillar Dam.
7. New contributions of the thesis
- The dissertation has proposed a new solution to increase the lateral bearing

capacity of the pile foundation of Pillar Dam in the Mekong Delta and determine
the reasonable size of this reinforced part.
- The thesis has built a relationship between the load and horizontal
displacement (p ~ y) for the representative weak soil type and for the foundation
surface reinforcement layer. Thereby determining the foundation and method of
determining lateral bearing capacity to apply the design of the pile foundation of
Pillar Dam.
8.The layout of the thesis
The layout of the thesis consists of: Introduction; 4 main chapters;
Conclusions and recommendations; Published articles and Reference


3

CHAPTER 1: OVERVIEW OF PILLAR DAM AND SOLUTIONS TO
INCREASE LATERAL BEARING CAPACITY FOR
PILE FOUNDATIONS IN SOFT GROUND AREAS
1.1 Overview of Pillar dam
1.1.1. Introduction of Pillar dam technology
The principle of Pillar dam is to bring the entire force into the work to
separate pillars, then transfer them to the ground through the pillars. Between the
pillar is the gate and waterproof structure.

Figure 1.1: Model of Pillar
dam

The advantage of Pillar dam is possible to construct it on the natural river, to
build constructions in weak geological conditions, with the depth of the soft soil
layer as in the coastal estuaries or ancient alluvial areas.
1.1.2 Research situation and application of Pillar dams in the world

From the early years of the twentieth century, the type of river containment
working as Pillar dam has been researched and applied many countries.
Large-scale works are concentrated in countries with strong scientific and
economic development such as Germany, England, etc. with the task of
preventing tides or controlling tides and preventing flooding.
1.1.3 Research situation and application Pillar dam in Viet Nam
Pillar dam technology was researched by the Institute of Water Resources
Research from 1991-1995 in the National Independence scientific Project KC1210. Structure and principle of Pillar dam as shown in figure 1.1.
Up to now, the Pillar dam technology has been applied to build many riverbarrier construction in Viet Nam and brought tremendous economic and technical
efficiency, such as: Thao Long (TT Hue), Nhieu Loc-Thi Nghe (Ho Chi Minh
City), Bien Nhi, Bao Chau, Vam Dinh (Ca Mau), Nha Mat (Bac Lieu), Bau Dien
(Tien Giang), Kenh Cut (Kien) Giang), Cau Xe (Hai Duong),... Currently, Ho Chi
Minh City Flood Control Project are applying Pillar dam technology to build, the
width of gate is from 40 - 160m;


4

1.1.4. Issues that need to be further researched when applying the Pillar
dam in the Mekong Delta and Vietnam
Although the Pillar dam has been researched and applied in Vietnam for a
long time, but the condition of the deep water level and large water column caused
a great horizontal load, the design of this construction is still difficult due to the
possibility of Horizontal resistance is limited compared to traditional
constructions. For the Mekong Delta, the deep soft soil layer is also a difficulty
when applying Pillar dam. For a long time, measures to increase the lateral
bearing capacity of pile foundation were oblique piles or large oblique piles.
Therefore, necessary to continue researching other solutions to increase the lateral
bearing capacity of pile foundation.
1.2 General assessment of geology in the Mekong Delta to the working

ability of pile foundation which is regularly subjected to horizontal load
1.2.1. Distribution and characteristics of soft soil in the Mekong Delta
The Mekong Delta is covered by quite thick young sediments, the common
composition of this layer is weak soil: weak clay, flowing sand, mud ... According
to the characteristics of geology, engineering geology, hydrogeology where
divided into five soft land areas. This soft clay has the most basic physical and
mechanical characteristics as follows:
+ Natural density of soil: γ = 14.5 ÷ 15.5kN / m3
+ Natural soil moisture: w = 75% ÷ 65%
+ Natural hollow coefficient of soil: e = 1.5 ÷ 2.0
+ Mechanical characteristics of soil: φ = 4o ÷ 5o, c = 5 ÷ 6kPa
+ Distortion characteristics of soil: Eo = 500 ÷ 600kPa
The thickness of soft clay in the Mekong Delta is usually from 0 ÷ 40m.
1.2.2. Geological foundation of Pillar dam constructed in the Mekong Delta
Based on the geology summation at works which is applicated of Pillar dam
technology in the Mekong Delta, within the range of 0 to 5 m, the soil at the top of
the pile (φ = 3-5o, c = 1–5kPa, γ = 1.5 –1.65kN / m3).
1.2.3. The note when contructing Pillar dam in the Mekong Delta
- Most of the Pillar dam have pressure on the foundation p> 300 ÷ 500kPa, so
it is needed to treat the foundation when contructing. The soil has a small water
permeability coefficient, so the consolidation speed is slow, subsidence is long.
Therefore, so reinforcing surface treatment should pay attention to solutions to
accelerate the drainage process so that the ground consolidates quickly.
- The relationship between stress and deformation of weak soils is nonlinear,
so the application of the extended Winkler model is consistent with the working
reality of the lower ground of dam.
- Foundation solution for the Pillar dam is to use pile foundations, which be
used to rconcrete piles, bored piles, prestressed concrete piles, steel piles ...
1.3. Solutions to increase lateral bearing capacity for pile foundation
Pile foundation of Pillar dam is usually subject to large horizontal load, there

are 2 main solutions to strengthening of the foundation is: arrangement of oblique


5

piles in the foundation or increasing the lateral bearing capacity of the single pile
in the pile group. Each solution has different advantages, disadvantages and
application conditions. For Pillar dam, the proposed solutions must be convenient
because the pillars have a load capacity of several hundred to a few thousand tons
for a pillar, so the number of piles is so many.
1.3.1 Solution of oblique piles: Use oblique pile or large oblique pile to move
horizontal load to axial load.
1.3.2. Solution to reinforce surface layer
1.3.2.1. Influence of soil around the pile to lateral bearing capacity of the pile
When the pile is under horizontal force,
the ground on the side of the pile appears to
resist the force. The chart of the resistance
force of cohesive soils is shown in Figure
1.2:

Figure 1.2: Distribution of soil resistance
pressure on piles
For cohesive soils, the value is considered constant, the depth arising at a
depth of 1.5d from the ground. The mechanical properties of the soil and topsoil
greatly affect and directly affect the lateral bearing capacity of the pile. When
improving the properties of the surface reinforcement layer, the lateral bearing
capacity of the pile will improve compared to the natural soft ground in the
Mekong Delta. The handling options are as follows:
1.3.2.2. Use crushed stone, grit or other raw materials
Use this material on the ground around the pile because of the large internal

friction angle, large ground ratio. Reinforcement can be carried out before or after
the installation of the pile. The downside is that it is difficult to inspect the
construction in the country. The contact between the pile and the rock layer will
be uneven, resulting in inaccurate calculations.
1.3.2.3 Using solution to improve the ground by soil-cement pile
The solution to improve the soft ground for pile foundations with deep
mixing method technology is to create cement piles in the soft soil layer of the
pile foundation surface.
Forms such as: reinforcing the scope under the pillar footing, around the
bearing piles or reinforcing the blocks surrounding the pillar footing. For pillar
dam, the author proposes solutions to reinforce under pillar footing. The
calculation of piles in this case the reinforced layer is converted to a base layer
and calculated as the case of multi-layer foundation.
This solution is relatively simple, however, specific calculations need to be
made based on geological conditions, type of foundation, type of pile as well as
reinforced cement content. This solution is most suitable and effective for pile
foundations with the substrate surface is soft ground.


6

1.3.2.4. Use concrete mortar
Bottom layer of concrete is often used with concrete grade B20 (M250). The
disadvantage is that the elasticity of the bottom concrete layer is not available, so
the lateral bearing capacity of this layer is difficult to determine; often the depth
of the bottom layer is much smaller than the depth of influence of horizontal load
so the effectiveness of the solution is not high. This solution is suitable and
effective for pile foundations with sandy or hard clay foundation.
1.3.3. Selecting the research solution of the thesis
In thesis, the author focus on researching solutions to increase the lateral

bearing capacity of single piles in the pile group. These types of reinforcement
materials have the effect of increasing lateral bearing capacity for pile
foundations, but the construction ability can greatly affect the research results. In
those categories, the reinforcement soil cement piles was selected to research.

1.4 Researches on soil-cement reinforcement for soft soil
1.4.1 The situation of application of soil cement to reinforce in the world and in VN
Technology to improve soil by cement, cement - lime has been researched
and applied since the 1960s, typically the US and Japan. This technology is used
in many road and railway projects such as: nailing, stabilizing excavations,
stabilizing slopes, reducing vibration ...
In Vietnam, the research of deep soil consolidation was started in the early
1980s. In 2002, a number of projects began to use soil cement piles to reinforce
the weak ground. In hydraulic works, since 2005 the soil-cement pile has begun to
be applied. The initial goal was to treat the ground waterproofing of the sluices.
After that, the soil cement piles are further researched for the purpose of
waterproofing and reinforcing the foundation for other types of works.
1.4.2 Researches on soil-cement piles in reinforcing soft ground in the Mekong
Delta
Vietnam Academy for Water Resources has applied the soil-cement pile
technology in foundation treatment and waterproofing of hydraulic works in the
Mekong Delta and it has brought about certain technical and economic efficiency.
Some specifications of common soil cement piles in the Mekong Delta:
Pile diameter: 60cm - 80cm
Cement content: usually use 300kg/m3
The compressive strength depends on the soil type (Table 1.1):
Table 1.1: Strength of soil cement pile with some typical soft soil types
Compressive strength (kPa)
TT
Soil type

(28 days)
(90 days)
1
Clay mixed, flowing plastic
634-906
1032-1123
2
Flexible plastic clay
630-814
886-1057
3
Clay
430-690
684-980
4
Peatification
184-236
116-164
5
Organic clay and mud
551-973
856-1156


7

1.4.3 pplication of soil cement piles to reinforce pile foundations in Japan
Since 2001, Japan has begun researched and applied soil cement piles to
increase the lateral bearing capacity for pile foundations, such as the Yabegawa
Bridge of the Ariake Expressway Project, Fukuoka district, Japan. The bored piles

were used with the depth of 50m, the reinforced soil cement pile with the length
and depth of B = 16.8m and Hgc = 10.5m. The application of soil cement pile has
brought remarkable economic and technical efficiency, especially the reduction of
vertical piles, reduced horizontal displacement and better earthquake resistance.
However, the design methodology was not established, but only field
experimented at each individual site.
1.5 Conclusion of chapter 1
- Although it has been researched and applied in practice, there are still many
issues that need to be further research and complet in theory to apply the design,
especially to the soft ground in the Mekong Delta.
- The solution to increase lateral bearing capacity for single piles and for pile
foundations selected for research orientation in the thesis is the solution to
reinforce the surface layer of pile foundation surface, the top of the pile with soil
cement piles – deep mix method technology.
- Currently, there is no announcement on the calculation theory to determine
the scope of the reinforcement layer, so it is necessary to research by
mathematical models and field experiments to give methods to identify and
evaluate the effectiveness of The above mentioned reinforcement solution is used
for lateral bearing capacity of pile.

CHAPTER 2: SCIENTIFIC BASIS OF SURFACE LAYER
REINFORCEMENT SOLUTION
2.1 Factors affecting of surface reinforcement layer to pile foundation
When the Pillar dam has a Surface reinforcement layer, foundation is changes
properties and ground state stress, which will affect:
- Affect lateral bearing capacity of single pile.
- Affect vertical load capacity and negative friction phenomenon of pile.
- Affect lateral bearing capacity of pile groups
- Affect the load capacity of the ground under the surface reinforcement layer
- Influence of surface reinforcement layer on the settlement of pile

foundation.
2.2 Method of calculating single pile under horizontal load
2.2.1 The methods for calculating currently applied single-piles
For the stability problem of pile foundations in general and pile foundation in
particular always comes from the research results of a single pile. So the
calculation of a single pile is not only important. Currently, there are many
methods of calculating single piles, each calculation method has 3 basic
characteristics such as: Model of soil environment surrounding the pile; Properties


8

of the relationship between soil reaction (p) and lateral displacement of pile (y);
How to solve the problem.
2.2.2 Analyze and select the method of calculating single pile.
Due to the working characteristics of the base dam piles in the Mekong Delta
should group methods based on the ultra-limited resistance of piles such as the
Broms method and the Meyerhof method has many limitations because it is not
applicable to the multi-layer background and not Consider reaching the intensity
of the soil.
The method "curve p ~ y" for the calculation of the foundation pile in the
Mekong Delta is quite suitable by piles in multi-layer background and long piles.
Currently, with the development of computer technology, the commercial
software calculates piles, using curve theory p ~ y to solve the problems of more
and more piles and high reliability, typical such as: the Software Lpile compution;
Ensoft Group; Midas Software; Software FB_Pier...
2.3 Researching the influence of surface reinforcement layer in depth
2.3.1. Theoretical basis is determined the depth affecting hah surface layer
The thickness of the surface soil layer plays a decisive role to the
displacement and internal force of the pile. Depth influence is particularly

important. It depends on the type of pile, the physical and mechanical properties
of the surface layer
The influence depth is determined by some basic formulas as follows:
(2-1)
h = 2.(d + 1)
ah

hah = 3,5d + 1,5
(2-2)
The influence depth hah which according to (2-1) and (2-2) is a basis for
comparison with the research results to determine a reasonable depth of
reinforcement.
2.3.2 Research the influence of depth of surface reinforcement layer on lateral
bearing capacity to pile foundation using mathematical model
- The purpose of calculation is to determine a reasonable depth of
reinforcement, that value the pile and ground reinforcement have maximum
horizontal load. From there, propose a formula to determine a reasonable depth of
reinforcement layer.
- The purpose of the calculation is to determine a reasonable depth of
reinforcement with that value the pile and reinforcement foudation have the
largest horizontal force from which propose a formula for determining a
reasonable reinforcement layer depth.
- Selecting the type of research piles calculated in the model is reinforced
concrete piles which dimensions is accordance with commonly used reality, the
length of the selected piles must satisfy the condition of being a "long pile" type.
- Select reinforcement method: reinforce the suface soil layer of foundation
with soil cement pile, the reinforcement layer is around pile.


9

- Diagram of calculation: Calculating for cases natural ground; determine the
reasonable depth for each type of pile in case reinforcement by soil-cement.
- To research the lateral bearing capacity, it is necessary to base on the theory
of p ~ y curve. When assigning a pile to a forced displacement the pile will have a
horizontal force that is directed against the direction of the forced displacement.
- Calculation parameters:
+ Choosing reinforced structure is a type of soil cement pile D100cm,
cement content 300kg/m3
+ Calculation of soil cement pile parameters works as an equivalent
background.
+ Soil: Representative soil sample was taken in My Tho, Tien Giang:
Cu (kPa)
φ (degree)
g (kN/m3)
Layer1
14.2
4,35
15,8
Indicator of soil cement pile:
Cc (kPa)
φ (degree)
400
35
2.3.2.5. Calculation results
a) Case of the existing ground (natural foundation):

g (kN/m3)
18,0

Biểu$đồ$quan$hệ$giữa$SCTN$với$kích$thước$cọc$nền$tự$nhiên$
40"
35"
30"

Sức$chịu$tải$ngang$(kN)$

Figure 2.1: Relationship
diagram between lateral
bearing capacity with pile
size, natural ground

25"
20"
15"
10"
5"
0"
5"

10"

15"

20"
25"
kích$thước$cọc$(cm)$

30"

35"

40"

b) Calculation results for reinforcement cases with different depth for each
type of pile as shown in Figure 2.2:
Biểu"đồ"quan"hệ"giữa"sức"chịu"tải"ngang"với"độ"sâu"gia"cố""

Figure 2.2: Relationship
diagram between lateral
bearing capacity and
reinforcement depth

"Sức"chịu"tải"ngang"(kN)"

250"
200"
SCTN"Cọc"20"

150"

SCTN"Cọc"35"
100"

STCN"Cọc"40"
SCTN"cọc"10"

50"

SCTN"cọc"30"

0"
0"

0,5"

1"

1,5"

2"

2,5"

Độ"sâu"gia"cố"(m)"

3"

3,5"

4"

4,5"


10

2.3.2.7. Proposing the method of determining
the depth of reinforcement
Biểu#đồ#quan#hệ#giữa#kích#thước#cọc#với#độ#sâu#gia#cố#

From the results of
4"
y"="12,473x "+"0,2719x"+"1,3726"
the research of the depth
R²"="0,99499"
3,5"
of the pile corresponding
to the pile type, the
3"
author has determined
2,5"
the
reasonable
2"
reinforcement
depth
value of pile types,
1,5"
thereby
building
a
1"
relationship between the
0"
0,05"
0,1"
0,15"
0,2"
0,25"
0,3"

0,35"
0,4"
0,45"
reinforcement depth and
kích#thước#cọc#(m)#
pile size as figure 2.3.
Figure 2.3: Relationship diagram between reinforced depth and pile size
From the chart have got the formula to determine the reasonable depth of
reinforcement as follows:
Độ#sâu#gia#cố#(m)#

2

Hgc = 12.5D2 + 0.27D + 1.37

(2-3)

D is the diameter or edge of the pile (m)
2.4 Research the influence of surface reinforcement layer on the ground
2.4.1. Theoretical basis for determining the size of reinforced layer on the ground
a) Theoretical basis
On the ground, the reinforcement area must be large enough for the surface
reinforcement layer to work well to increase the lateral bearing capacity of the pile
in the foundation. Types of reinforcement applicable: Reinforcing the entire area
of the bottom of the pillar; Reinforced around the perimeter of the pillar
b) Permissible horizontal displacement of pile foundation of Pillar Dam
Determine the permissible horizontal displacement of the pile as a basis for
lateral bearing capacity research with the scope of reinforcement on the ground.
Horizontal displacement allows taking according to the current standards, but
for Pillar dam, in order to ensure the good working of the valve gate structure and

the waterproofing structure, select the allowed horizontal displacement of the pile
[y] = 25mm.
2.4.2 Research the influence of surface reinforcement layer on lateral bearing
capacity of pile foundation using mathematical models
The purpose of calculation is to determine the reasonable length of
reinforcement which lateral bearing capacity is max. From that, propose a method
to determine the length of the reinforcement layer and build the relationship
between lateral bearing capacity with the piles types.
Using software of Geotechnical Midas GTS NX version 2014 - Korea GTS
NX to research the reinforcement length.


11

Calculation of cases with changing layer lengths: Begin equal to 5D, then
gradually increase each level compared to 25cm, until the influence of the length
of the reinforcement layer is over.
The method chosen for calculation is the reduction method ϕ, c. The
principle of calculation is to gradually reduce the shear resistance of the substrate
to the point where an instability occurs. The rate of maximum reduction in shear
strength at that time was considered to be the minimum safety factor.
Calculating diagram:
- The model is built on Midas - GTS software.
- Geological parameters of the foundation and reinforcement layer section 2.3
- Model size:
+ Model length and height vary with each pile size (equal to 2 times the
pile length);
+ The width of the model is not less than 5D (D is the diameter of pile).
+ Depth of reinforced block calculated by the formula (2-3)
+ Width of reinforcement block resemble the width of model

+ Single pile has the length of each pile size (Table 2.1)
Table 2.1: Size of research model determining reasonable reinforcement length
pile size (cm)
Reinforced
Reinforced
Length
No
depth (m)
width (m)
of piles
Square
Round
centrifugal
(m)
pile
pile
piles
1
10x10
10
10
1,52
0,5
6
2
20x20
20
20
1,92
1,0

6
3
30x30
30
30-6
2,58
1,5
15
4
35x35
35
35-6
3,00
1,75
15
5
40x40
40
40-6.5
3,48
2,0
15
6
60
60-9
6,03
3,0
30
2.4.2.1. Calculation results
Calculate and build a relationship diagram between lateral bearing capacity

with reinforcement length
for each type and size of
research piles as follows
(Figure 2.4 is typical
square pile):
Figure 2.4: Relationship
diagram between lateral
bearing capacityof square
piles and reinforcement
length
2.4.2.2. Commenting on the research results:
When increasing the length of reinforced blocks, the lateral bearing capacity
of piles increased, but to a certain extent, despite the increase in length, the lateral
bearing capacity has not increased. This shows that, reinforcing length Lgc to a


12

certain critical value will maximize the influence of reinforcement.
Reasonable reinforcement length depends only on the size of pile D and not
on the shape of pile.
2.4.2.3. Propose a formula to determine the length of reinforcement
Biểu&đồ&quan&hệ&giữa&kích&thước&cọc&với&chiều&dài&gia&cố&
From the results of calculating the
reasonable reinforcement length of piles,
the author built a relationship 5,0"
diagram between the depth of reinforcement and
pile size as shown in Figure 2.5.4,5"
Chiều&dài&gia&cố&(m)&

4,0"

Figure 2.5: Relationship
diagram between
reinforcement length and
pile size

y"="$1,9536x2"+"5,0707x"+"1,1901"
R²"="0,98429"

3,5"
3,0"
2,5"
2,0"
1,5"
1,0"
0"

0,1"

0,2"

0,3"

0,4"

0,5"

0,6"

0,7"

kích&thước&cọc&(m)&

From there, formulate a formula to determine the reasonable reinforcement
length as follows:
Lgc = -1.95D2 + 5.07D + 1.19 (m) (2-4)
After determining the reasonable reinforcement length, the author calculates
and builds a relationship diagram between lateral bearing capacity with the size of
the types of piles as shown in Figure 2.6.
230#
210#
190#

Sức$chịu$tải$ngang$(kN)$

Figure 2.6: Relationship
diagram between lateral
bearing capacity and
size of pile types

170#
150#

cọc#vuông#

130#

cọc#tròn#

110#

cọc#ly#tâm#

90#
70#
50#
5#

10#

15#

20#

25#

30#

35#

40#

45#

50#

55#

60#

65#

Kích$thước$cọc$(cm)$

2.5 Conclusion of chapter 2
- By using the method of software numerical analysis, the author has clarified
the influenceiveness when reinforcing the pile foundation layer with soil cement
pile, detail:
+ After reinforcement, the hardness and intensity of the pile surface on the top of
the pile increasing the pile's lateral bearing capacity is improved.
+ The reinforced range lateral bearing capacity of pile is linearly correlated,
however, to a certain reinforcement range, the influence of the reinforcement
block is not further promoted.


13
+ The value of the reinforced range to which point even though the scope of
expansion is increased but the lateral bearing capacity of vertical pile does
not increase, is called a reasonable depth and length of reinforcement.
- This chapter, the author has built a method to determine the reasonable size
of reinforced blocks using soil cement pile to increase the lateral bearing capacity
of pile as well as determine the calculated lateral bearing capacity of single piles
after reinforcement.
- The results of the research by mathematical model should be verified by a
physical model in the same condition of the ground and soil cement reinforcement
layer to clarify the effectiveness of the reinforcing block and recommend
supplementing to the theory of foundation calculation.

CHAPTER 3: EXPERIMENTAL RESEARCH THE INFLUENCES OF

REINFORCEMENT LAYER BY PHYSICAL MODEL
3.1 General introduction to experimental research
The objective of the thesis is to apply the solution of reinforcing surface layer
of pile foundations in the Mekong Delta, so the experiments are conducted in the
representative area in this regon with the commonly used piles. Due to the
limitations of the experimental equipment, the 1.5 - 2m thick reinforcement
cannot be done by creating soil cement reinforcement layer, therefore, in this
experiment, the layer of soil cement reinforcement has the same specifications as
the soil cement pile but mixed by machine and poured by hand.
3.2 Objectives, content and requirements of the experiment
3.2.1. Objective of the experiment
Experimenting, measuring, assessing the lateral bearing capacity of piles in
cases of working on natural soft ground and the foundation after surface layer
reinforcement. On that basis, compared with the theoretical method studied, from
which there is a conclusion about the influenceness of the solution of reinforcing
the foundation layer of the surface facing the horizontal load of the pile
foundation, as a basis for calculating the foundation design piles for pillar dam in
the area of the Mekong Delta;
Through physical model experiments, we can determine the base k and build
p ~ y curves for natural ground and surface layer after reinforcement.
3.2.2. Experimental research method
From the method of calculating the lateral bearing capacity of a single pile,
the measurement research on physical model with a ratio of 1: 1, load and
displacement of the pile head in the case of working piles in natural soft ground
and the ground after reinforcing the surface layer; Measure the surface
displacement of the reinforcing block to assess the reasonable range of the
reinforcement layer.
3.2.3. Scope of experimental research: Representing the natural soft ground in the
Mekong Delta, the experiment was conducted in My Tho City, Tien Giang Province.

14

3.2.4. Object of experimental research: Vertical single pile with horizontal load,
surface reinforced layer is soil- cement piles
3.2.5. Research content.
The results of the mathematical model have identified the reasonable
reinforcement scope for each type of pile. Building physical models and measure
some specific cases to compare results with theoretical methods. From there, there
was a conclusion about the reinforcement solution and recommendations in
calculating a single pile under horizontal load.
3.3 Building experimental models and laboratory equipment
3.3.1. Building experimental models
Building an experimental model with a scale of 1: 1 at the actual scene in the
Mekong Delta - in My Tho City, Tien Giang Province, including:
+ Experimental piles: Reinforced concrete piles, square piles with cross
sections of 10x10cm, 20x20cm and 35x35cm, round piles with diameter D =
10cm, 20cm and centrifugal piles D40cm. The length of the piles is determined
after checking the soil foundation where the testing piles, with piles of 10cm and
20cm sides of 6m length, with piles of 35cm and 40cm sides of 15m length.
+ Pedestal: Including 3piles (30x30cmx12m), closed in triangles, piles are
poured with reinforced hexagon reinforced concrete 50cm;
+ Frame support system, sheave, jack, cast steel
+ Experimental ground includes 2 cases: natural ground and reinforced
concrete ground layer. The reinforced concrete layer in the experiments carried
out in this research was used according to the grade of cement piles commonly
used in the Mekong Delta and the size as Table 3.1.
Table 3.1: Parameters of piles and reinforced experimental models
Pile type (cm)
Reinforced block size (m)

Pile length
(m)
Square pile
Deep
Wide
Long
10
6,00
1,52
1,00
2,48
20
6,00
1,92
2,00
3,06
35
15,00
3,00
3,50
3,77
Round pile
10
6,00
1,52
1,00
2,48
20
6,00
1,92

2,00
3,06
40
15,00
3,48
4,00
3,96
3.3.2. Experimental equipment and instruments
Experimental equipment consists of three parts: loading equipment, jet
equipment, measuring equipment, as shown in Figure 3.1:
1. Jetpack; 2. Pre-buried steel plates; 3. Jet rack 4. Pressure sensor 5. Jack; 6.
Experimental pile; 7: Benchmarking; 8. Displacement sensor; 9. Steel plate for
monitoring displacement of the ground.


15

Figure 3.1: Diagram of
experimental equipment

The main equipment for the experiment includes:
a) Load device: use the jack to load, the force measuring sensor to measure
the impact load
b) Jet equipment
The jet is greater than 1.5 ∼ 2 times the maximum estimated load-bearing
capacity of the experiment, the stiffness in its direction of force shall not be less
than the rigidity of the experiment pile itself.
c) Arrange a benchmark to measure the displacement at the point of impact
force of the pile, using a steel rod to be inserted into the soil 1.5m deep as a
reference point. The entire system of standard equipment is arranged

independently to reduce the impact of reinforced blocks and ground.
d) Measuring devices:
- Two-dimensional mechanical jacking: To increase and discharge the impact
load into the pile head
- Loadcell 20 tons: displays the impact force value at the top of the pile
- Data taker: Device to record measurement data is transmitted to a computer,
can connect and record data simultaneously on multiple measurement modules.
- Induction displacement measurement rods across the pile head:
- Bar displacement sensor for measuring the area of influence of the
reinforcing layer:
- Wire displacement sensor for measuring the area of influence of the
reinforcement layer
- Slotted surcharge weight: To measure the horizontal displacement of the
pile head according to each different load level.
- Equipment to record measurement signals: use to record data from
measuring devices for display on computers.
- Laptop: For saving and processing data from Data taker
- Digital camera: To take photos of experiments.
e) Other equipment:
- Water pump: Serving water pump in and out of experiment scope
- Piling machine: is a form of diesel hammer with hammer head weight>
2.0T placed on the crane array> 20T to serve the experimental pile driving.
- Equipment for excavating soil and reinforced concrete blocks;
3.4 Cases and sequences of experiments
3.4.1. Experimental cases


16

Lực$ngang$đầu$cọc$(kN)$

The experiment cases to determine horizontal load and displacement include:
a) Experiments on natural ground: Horizontal load and continuous record
until the displacement pile is 10mm, take the value to calculate the ground
coefficient of the natural soil, then continue the load to the displacement value of
25mm and until the pile or foundation is broken destructive. During horizontal
load, data on horizontal force and displacement are measured and recorded in
computer.
b) Experiment with reinforced background: The top layer of pile foundation
is reinforced with cement-soil layer. For each type of pile will have different
thickness and width of cement reinforcement layer. The experiment is similar to
the experiment on natural ground, however, the reinforced layer behind the pile is
measured to determine the displacement of the reinforced area on the ground.
3.4.2. Installation of equipment and experiment sequence
a) Installation of equipment: To accomplish the purpose of experimenting,
measuring the impact force, displacement of the pile head, the displacement of the
reinforced layer behind the pile, at locations where the comparisons of the
measuring heads are to be compared.
b) Experimental sequence
+ Construction of jet posts.
+ Preparing experimental piles with sufficient strength, driving piles to be
submerged in the ground at the experimental positions, except for the tip of 0.5m
to set the horizontal force point.
+ Digging deep soil and constructing reinforcing blocks according to
reasonable size. Sampling and curing sample (9 indicators)
+ Install a displacement measuring device in the reinforced foundation at the
points behind the pile
+ Experimenting XMĐ samples at 28 days and 91 days. After 28 days of
conducting experiments pushing the pile for each individual module.
3.5. Experimental results

3.5.1 Experimental results for square piles
Experimental results
170"
160"
for all types of square
150"
140"
piles are shown by
130"
diagrams of relationships
120"
110"
between load and pile
100"
90"
head displacement p ~ y
TH"nền"tự"nhiên"
80"
70"
in two cases: natural and
60"
TH"nền"gia"cố"
50"
reinforced are shown in
40"
each diagram, typically
30"
20"
as follows:
10"

0"
0"

5"

10"

15"

20"

25"

30"

Chuyển$vị$ngang$đầu$cọc$(mm)$

Figure 3.2: P ~ y relationship diagram for square pile 35x35cm

35"

40"


17

Lực$ngang$đầu$cọc$(kN)$

3.5.2 Experimental results for round piles
50"

Experimental results
45"
for the types of round
40"
piles are shown by the
35"
diagram
of
the
30"
relationship between the
25"
TH"nền"tự"nhiên"
load and pile head
20"
TH"nền"gia"cố"
displacement p ~ y in
15"
10"
two cases: natural and
5"
reinforced are shown in
0"
each diagram, typically
0"
5"
10"
15"
20"
25"

30"
35"
40"
Chuyển$vị$ngang$đầu$cọc$(mm)$
as follows:
Figure 3.3: Relationship diagram p ~ y for round pile D10cm
From the results of the physical model research, the relationship between
Biểu$đồ$quan$hệ$SCTN$với$kích$thước$cọc$vuông$thí$nghiệm$
lateral bearing capacity and pile
size is obtained:
160"

Lực$ngang$đầu$cọc$(kN)$

140"
120"
100"
80"

TH"tự"nhiên"

60"

TH"gia"cố"

40"
20"
0"
0"

5"

10"

15"

20"

25"

30"

35"

40"

Kích$thước$cọc$(cm)$

Biểu$đồ$quan$hệ$SCTN$với$kích$thước$cọc$tròn$thí$nghiệm$
Figure 3.4: Diagram of lateral
bearing capacity and square pile size
180"

Figure 3.5: Diagram
of lateral bearing
capacity and round
pile size

Lực$ngang$đầu$cọc$(kN)$

160"
140"
120"
100"
80"

TH"gia"cố"

60"

TH"tự"nhiên"

40"
20"
0"
0"

5"

10"

15"

20"

25"

Kích$thước$cọc$(cm)$

30"

35"

40"

45"

3.5.3 Comment on the experimental results
From the diagrams of relationship between load and displacement shows that
within the permissible range of support pillar (<25mm) the lateral bearing
capacity increases proportional to the pile diameter. In the case of reinforcing


18

ground, outside the permissible displacement range (up to 25mm) the load value
tends to be inversely proportional to the displacement, which indicates that the
reinforced mass forms a critical displacement. Experimental results also show that
the critical displacement value of piles, the pile size does not have a large
difference, which means that the soil cement layer has reached the destructive
boundary, so it is not influence. about transposition.
Therefore, it can be concluded that the increase in horizontal bearing capacity
of the pile depends on the type of pile, the shape of the pile, the ground and
reinforced materials. The critical value of displacement depends on the material
used to reinforce the surface layer.
3.6 Compare field experiment results with calculation model
3.6.1 Comparison of lateral bearing capacity of piles
Through field test results and calculations with the same pile foundation size
and ground parameters, the author found that, for natural cases, the results
between experiments and calculations are relatively similar. In the case of

reinforcement found that the actual load capacity is lower than the calculation of
about 5%.
Table 3.2 Comparing lateral bearing capacity of square pile between calculation and
experiment
Size
Comparing between
calculation
experiment
pile
experiment and calculation (%)
10
45,6
42,62
93,5
20
93,2
90,37
97,0
35
164,3
156,21
95,1
Average
95,2
Table 3.3 Comparing lateral bearing capacity of round pile between calculation and
experiment
Comparing between experiment
Size pile
calculation
experiment

and calculation (%)
10
42,9
40,66
94,8
20
90,2
85,59
94,9
40
176,5
167,99
95,2
Average
94,9
3.6.2 Comparison of the sphere influence of the reinforcement layer on the ground
On the experimental field diagram, the author has installed the displacement
measurement points (2,3,4,5,6) of the reinforced layer surface behind the pile,
respectively, 40cm, 80cm, 120cm, 160cm and 200cm. Points 4, 5 and 6 cannot be
monitored and measured for any displacement value. Thereby the author found
that the influence of the reinforcement layer is very small.


19

3.7. Determine the ratio factor of the elastic stiffness of foundation
The ratio factor k is determined from the results of experimenting pile under
horizontal load, for 2 cases: typical natural ground and reinforced soil cement
layer, the results determine the ratio factor k as follows:
K-value of soil cement reinforcement and natural ground (T/m4)

Case

10x10

square plie
20x20 35x35

round pile
D10
D20

Centrifugal
D40

average

Reinforcement

42.262

41.129

41.154

41.824

41.182

41.350

41.483

Natural ground

1.850

1.809

1.841

1.893

1.825

1.804

1.837

3.8 Determine lateral bearing capacity of pile in case of reinforced
foundation
The solution chosen to reinforce the surface layer of the pile foundation with
DMM technology has a reasonable size determined. The author based on the
results of calculation and experiment to propose the method of lateral bearing
capacity of pile as follows:
- For square piles: use the chart in Biểu
Figure
3.6
đồ so sánh SCTN của cọc vuông
220"

SCTN"8nh"toán"

200"

SCTN"đề"xuất"

Sức chịu tải ngang (kN)

180"
160"
140"
y"="$0,0181x2"+"5,4259x"+"1,2937"
R²"="0,99998"

120"
100"
80"
60"
40"
5"

10"

15"

20"

25"

30"

35"

40"

45"

Kích thước cọc (cm)

Figure 3.6 The determine lateral bearing capacity with the size of square pile

Or use the formula:
P = -0,018D2 + 5,43D + 1,29 (kN)
(3.5)
D is the size of the square pile side (cm)
- For round piles or centrifugal piles:
useso the
Figure
Biểu đồ
sánhchart
SCTNin
của
cọc tròn3.7
ly tâm
250"

SCTN"8nh"toán"
SCTN"Đề"xuất"

Figure 3.7 The

determine lateral
bearing capacity with
the size of round pile

Sức chịu tải ngang (kN)

200"
150"

y"="$0,0545x2"+"7,0386x"$"13,874"
R²"="0,99874"

100"
50"
0"
0"

5"

10"

15"

20"

25"

30"

35"

40"

Kích thước cọc (cm)

45"

50"

55"

60"

65"


20

Or use the formula:
P = -0,055D2 + 7,04D – 13,87 (kN)
(3.6)
D is the diameter of the round pile (cm)
3.7 Conclusion of chapter 3
The results shown in this chapter serve as a theoretical clarification and are
the results of experiments conducted on specific soil types and reinforcing
materials in the Mekong Delta. Experimental results are quite similar to those
calculated using mathematical models. The bearing capacity of the pile increases
about 7 to 8 times within the selected displacement limit for pillar dam.
The value of lateral bearing capacity is recalculated by software with
parameters of ground, reinforcement layers and piles according to the

experimental model to determine the deviation between calculation and reality.
From there, it is the basis for proposing a method for determining the lateral
bearing capacity for each type of pile in the construction design.
To be able to investigate and analyze more fully the influence of reinforced
foundation on pile bearing capacity of piles for the whole Mekong Delta region,
the following experiments need to focus on examining the influence of mortar
aggregate. soil cement, the influence of soil types, the reinforced position above or
below the water table as well as the influence of pile groups, pile linkage.

CHAPTER 4: PROCESS OF CALCULATING PILE FOUNDATION
FOR PILLAR DAM IN CASE OF SURFACE
REINFORCEMENT LAYER
4.1. Selecting the method of calculating the lateral bearing capacity of
single pile
Pillar Dam in the Mekong Delta, often using long piles, weak clayey soils are
often very thick, it is recommended to use the p ~ y curve method to calculate
horizontal load piles.
4.2. Factors related to foundation calculation after foundation
reinforcement
4.2.1. The elastic stiffness of the foundation and lateral bearing capacity of single
pile.
4.2.1.1 Determine the ratio factor k of the elastic stiffness of the foundation
The ratio factor k is determined according to the tables in The design
standards of pile foundation, for other soil types or reinforcement layers, the
results from Chapter 3, section 3.7 are used.
4.2.1.2 Lateral bearing capacity of single pile.:
After reinforcing the surface layer on the top of the pile with DMM
technology, the reasonable size of the reinforced block was determined, calculate
the lateral bearing capacity of the single pile with the pile types and pile sizes
according to formula (3.5) for square piles and (3.6) for round piles.

21

4.2.2. Influences of pile groups
When the piles work in groups, the limited lateral bearing capacity of the pile
group is reduced compared to the total lateral bearing capacity of each single pile.
4.2.4. Select coefficients of pile groups
By researching the surface layer of the reinforced concrete pile foundation,
the number of Pillar dam, the distance of piles> 3d, the author analyzed the
research results of Rollins, Prakash and Saran to It is recommended to take the
group Gc coefficient of the pile in the pile foundation to serve the calculation of
the foundation of the pier to support the reinforced case as the following table:
S/d
3
3,5
4
4,5
5
6
8
Gc
0,4
0,45
0,5
0,55
0,6
0,65
1
- S is the distance between the centers of pile;

- d is the diameter or width of pile.
4.3 Design process of pile foundation Pillar dam in case of reinforced
foundation
The author proposes the steps to calculate the design of Pillar dam after
selecting the reinforced surface of pile foundation by soil-cement pile as follows:
Step 1: Surveying and assessing project geology.
Based on the survey results, to ensure stability of the Pillar dam, the only
option designing is pile foundation. Based on the stratum of the survey area to
propose a preliminary foundation pile by piles or bored piles.
Step 2: Determine tasks and scale of the work, arrange the structure of the
work and calculate loads acting on the project.
Step 3: Select the type of pier foundation and pile type
Step 4: Selecting solutions to increase lateral bearing capacity of pile
foundations. In this step, we will select the solution with cement reinforcement,
choose the level and type of reinforcement
Step 5: Arrangement of pile ground
Step 6: Calculate and determine the reasonable reinforcement block size.
After estimating the type of foundation, the pile type and the form of
reinforcement, the most reasonable size (depth and dimensions on the ground)
will be determined. The size of reinforcement block depends on the size of pile.
Step 7: Checking the stability of pile foundation after reinforcing the
foundation layer with soil-cement piles.
Step 8: If the conditions of displacement and stress in step 7 are not ok, then
go back to step 5 to re-select number of piles; pile size and reinforcing block size.
4.4 Apply research results to the calculation for actual constructions
To illustrate this calculation, Bau Dien construction (Tien Giang province) is
selected as a typical project to calculate and evaluate the effectiveness of
reinforcement. The author will design pile foundation for 2 cases of natural
ground and surface after surface reinforcement to compare the two alternatives.
4.4.1 Introduction to Bau Dien construction

22

According to the construction drawing design Bau Dien construction, Cai
Lay district, Tien Giang province, the project has the following parameters:
- Project: Construction of 5 canals north of National Highway 1, level III.
- Designed in 2010-2014, completed in 2015
4.4.1.1. Design criteria
- Frequency to calculate structural stability, P = 1%, building: P = 10%.
- Salinity and flood prevention combination: River level: + 2.19m; Field
level: + 0.5m.
- Fresh keeping complex: River level: + 0.8m; Field level: -1,36m.
4.4.1.2. Technical parameters
- Open drain type with reinforced concrete M300, Pillar dam technology.
- Clearance width: B = 20 m, including 2 gates.
- Elevation water intake sill = -3,00 m, elevation of water gate: + 2.50m.
- Handling pier foundation with M300 reinforced concrete piles of 35x35cm
section, piles deep into the geological layer about 3m to 5m.
4.4.2. Geological conditions of works
Physical and mechanical characteristics of the ground in the scope of the
survey include the following classes:
Layer 1: Blue-gray clay mud, sometimes with fine sand. This layer occurs in
all survey boreholes and is distributed under layers 1a to 11.6m in HK1 borehole;
7.8m in HK2; 7.1m in HK3; 7.2m in HK4 and 8.8m in HK5.
Layer 2: Clay, brown-brown, yellowish-brown and gray clay mixed clay:
plasticity state in all surveyed boreholes and distributed under layers 1 to 24.4m in
HK boreholes; 21.5m in HK2; 22.7m in HK3; 21.5m in HK4 and 22.8m in HK5.
Layer 3: Sand mixed with clay, gray brown, yellow brown, white gray with
compact texture. This layer appears just below layer 2, when drilling at the

designed depth of 30.0m, the bottom of the layer has yet to appear.
4.4.4 Calculation results of pile foundation in the case of natural ground
- Total number of piles: 40; Number of vertical piles: 12
- Number of oblique piles: bearing water column for irrigation load: 15;
bearing tidal water column load: 13
4.4.5 Calculation of foundation piles in case of foundation after reinforcement
Total piles: 20 and arranged in 2 rows, each row has 10 piles.
4.4.6 Assessment of economic and technical efficiency in two cases
4.4.6.1 Technical
Table 4.1 Statistics of Pillar piles of Bau Dien sluice gate foundation
Case of oblique
Case of soil No
Note
piles 1:7
cement pile
Total piles
40
20
Number of vertical piles
12
20
Number of oblique piles
28
0
2-side oblique
Reinforced volume
190m3
485m pile
D80cm

23

Comparing the calculated results in two cases: the natural ground of the
oblique pile foundation considering the bottom layer and the vertical pile
foundation, the reinforced soil-cement foundation shows that the number of piles
in the pile foundation decreased from 40 to only 20 vertical piles (reduced by 50%
of the number of piles) and no need any oblique piles.
4.4.6.2 Economic
In order to make the economic comparison, the author has determined the
construction volume of two cases for calculating the cost estimate with the price
as of the third quarter of 2018. The comparison results are shown in Table 4.13
Table 4.2 Total direct costs of Bau Dien pile foundation construction
Natural ground plan
Reinforcement
No
Direct costs
(VND)
foundation plan (VND)
1
Materials costs
345.833.818
528.551.514
2
Labor costs
325.274.577
167.102.406
3
Machine cost
477.404.382

248.511.300
4
Other direct costs
22.970.256
18.883.304
Total direct costs
1.171.483.031
963.048.525
The comparative results show that, with the reinforcement plan, Total direct
costs for building of pile foundation is reduced by 21.6% compared with the
natural foundation using oblique piles plan.

Conclusion of chapter 4
This chapter, the author presents the process of calculating lateral bearing
capacity of single pile and the design process of the Pillar dam foundation pile
after being reinforced by soil - cement surface layer.
In the basic 8-step process above, the initial determination of the type of
foundation, the type of pile and the selection of the pile size is the most important
because it relates to the calculation time, economic and technical efficiency of the
solution.
By calculating the actual construction in two cases: the natural foundation
and reinforced foundation show that the number of piles decreased from 40 to
only 20 vertical piles (50% reduction of the number of piles) and no need any
oblique piles.
CONCLUSIONS AND RECOMMENDATIONS
Conclusions
From the research results presented in the previous chapters of the thesis, the
author draws the conclusions as follows:
The thesis provides an analysis of solutions to increase the lateral bearing
capacity of Pillar dam on soft ground and focus on researching the influence of

the surface reinforcement layer of the foundation. In this solution, soil cement
piles were selected to reinforce the surface layer as the most suitable and feasible.
By using numerical methods and field experiments in the research, it showed
that the lateral bearing capacity of pile increased 7-8 times after determining the
reasonable size of the reinforced block.