- i -
MINISTRY OF EDUCATION AND TRAINING
UNIVERSITY OF TRANSPORT AND COMMUNICATION Hao Huynh Ngoc
A STUDY ON THE EMBANKMENT CACULATION
METHOD REINFORCED BY GEOTEXTILE IN THE
CONSTRUCTION OF HIGHWAY IN VIETNAM Major: Construction of hightway and street
Code: 62.58.30.01 SUMMARY OF Ph.D THESIS

- iii -
Publications

1. Hao Huynh Ngoc MS, Phung Vu Dinh Prof.PhD (2009), “Several
designing measures using geotextiles in order to stabilize weak soil in the
constructing of road and dam, dike”. Bridge and Road Magazine, N
o
.
Nov-2009, Page 8-11.
2. Quang Tran Dinh PhD, Hao Huynh Ngoc MS (2011), “Study of the
improvement for fabrication and construction of prestressed I beam l =
42m with continous thermo slad based on the construction of Hoa xuan
brigde- Danang city“, The Transport and communications magazine, N
o
.
Aug-2011, ISSN 0866-7012, Page 26-29.
3. Hao Huynh Ngoc MS, Phung Vu Dinh Prof.PhD (2013), “Probability of
instability of backfill construction from design perspective“, Bridge and
Road Magazine, N
o
. Aug-2013, ISSN 1859-459X, Page 19-22.
4. Hao Huynh Ngoc MS, Phung Vu Dinh Prof.PhD (2013),“The stability
caculation model of embankment (highways, dikes, dams) reinforced by
geotextile thanks to the finite element method and mention pull behaviors
of geotextile and relationship between stresses and strains of the contact
elements between embankment and geotextile“, Bridge and Road
Magazine, N

roads in Vietnam becomes necessary .
Within the scope of this study , the author used the finite element method -
numerical method has several advantages in the present time to apply the
construction algorithm , based on the programming software suit Vietnam and the
conditions for a number of research results stability problems , stress - state
deformation embankment , proposed making calculations and charts used in
utility design .
2 - Reasons for choosing topic : To complete calculation methodology for
problem embankment using geotextiles in the construction of highways
3 - Purpose : Develop computational models roadbed embankment reinforced by
geotextile , contribute to improve the calculation method actually worked closely
with the material and the ability to predict an instability correctly in order to bring
high efficiency , ensure technical requirements designed embankment geotextile
reinforcement
4 - Research Subjects : The land cover using geotextile in road works background
5 - Scope of the Study : Selection , calculation model building problem
embankment geotextile reinforcement . Construction algorithms and computer
programs using the finite element method . Look at the problem embankment
geotextile reinforcement .
6 - The meaning of scientific and practical subjects : geotextiles is a new material
made from synthetic polymer materials or products related to the polymer through
different manufacturing technologies together. Since the 70s of last century
geotextile fabric was born in the western world . Due to the interesting properties
of geotextile Vietnam should have quickly been used to enhance reinforcement
load capacity and stability for the construction, especially the building
embankments in road and bridge construction and irrigation
The early years of the '90s - last century, geotextiles are widely used in many
countries such as France , the Netherlands , the U.S. and Japan , particularly in
Southeast Asian countries like Thailand , Philippines , Indonesia , Malaysia , in
our country , geotextile be put to use building the road since 1993 and more using

construction projects like highways : highways Ho Chi Minh City - Trung Luong
, Thang Long Boulevard ( away from Lang Hoa Lac ) , high speed Hanoi - Hai
Phong Expressway Gie - Ninh Binh , Noi Bai - Lao Cai Highway Long Thanh -
Dau Giay Expressway and Ben Luc - Long Thanh
1.1.1.2. Classification of geotextile [14] , [28] , [29] , [30] Based on the
fabrication technology , geotextiles are classified into two types : woven
geotextile and silk geotechical kind of non-woven .
Some evaluation criteria geotextile : Appendix 1 : Table 1.3 introduces the main
physical and mechanical by application of geotextiles ; Table 1.4 specifications
polyfelt TS nonwovens ; Table 1.5 and Table 1.6 non-woven geotextile HD -
Vietnam [ 50 ] .
1.1.1.3 The function of geotextile [13] , [14] , [27] , [31] , [34] , [35] , [36] , [38] ,
[44], [56], [58], [61], [62], [63], [66], [68] .
1 . functional separation between the layers of material together ( separation )
Geotextile separation layer is made between the buffer layer of sand and mud
below , separated between subgrade below ( subbase ) and the bottom layer of
pavement covered with sand on top .
2 . Functional soft soil reinforcement (reinforcement) For high embankments on
soft ground , it reaches a certain height sliding platform will emerge - the whole
- 3 -
block sliding , sliding local slope should therefore use geotextile TECHNICAL
reinforcement . Geotextile can also be used in case of reinforced soil need not
weak but the background causeway .
3 . Geotextile reinforcement retaining wall (wall soft key) to increase the ability to
land up tall retaining wall , or steep to 900 degrees , people use geotextile wall
build certainly unsatisfactory medium height wall covering , durability and use
landscaping aesthetics but cheaper from 25 % to half of the reinforced concrete
wall [14] , [19] , [34] , [44] , [45] .
4 . Function filtering , drainage behind the retaining wall ( drainage ) ( or a system
of underground drainage embankment works on traffic , irrigation ) , was

to unstable surface . With this function geotextile was also used in the upgrade of
Highway 5 , National Highway 1 , QL10 , QL18 and some highways such as
- 4 -
Highway District. Ho Chi Minh City - Trung Luong ; Gie - Ninh Binh , Noi Bai -
Lao Cai , Ha Noi - Hai Phong , Ha Noi - Thai Nguyen Also geotextile is used
in landfills to make division between land and the class rubbish such as landfill
bottom liner Tam Tan (Cu Chi , Ho Chi Minh City , 2011) , landfill Bo Trach
district (Quang Binh) , landfill Nhon district (Binh Dinh) , Hung Yen city landfill

2 . Geotextile reinforcement function embankment on soft soil : In the years 2000-
2003 , before the construction of embankments online Troi - Vu Oai [ 40 ] , grade
III Delta (Quang Ninh) , chaired set design was used 2 , 3 layers of geotextile
separation layer by doing medium duty reinforcement for embankment on soft
soil . Also in 2002, on National Highway 1 bypass the city of Vinh [ 39 ] design
chair used as geotextile separation layer between the soft soil at a depth of 80cm
and digging up sand poured on . Then continue to use 3 more geotextile layers ,
each layer separated by 40cm to reinforcement training background ( 80cm ) and
section 4 ÷ 5 m high embankment . Two works have exploited so far ( 2013 ) is
more than 10 years , very good quality . This is the process of using geotextiles to
handle embankment on soft soil for the first time in Vietnam , simple construction
, reduced construction costs . Two works make a good premise for the use of
geotextiles for reinforcement of soft soil embankment on many other road
construction projects such as highways , Ho Chi Minh City - Trung Luong , Gie -
Ninh Binh, Ha Noi - Thai Nguyen, Noi Bai - Lao Cai,… .
3 . Geotextile for erosion control functions When slope embankment built to
protect the coastline of Bai Chay - Quang Ninh , geotextiles are used to spread on
the embankment slope surface , then place over the stones deck form concrete
brick cement to prevent erosion of the dam due to heavy pressure waves . Also
geotextile was also used to protect , reinforced slope reservoirs such as reservoir
park Lao Cai city center ( designed in 2000 by the Department of Transportation

stress conditions ; fms : partial material factor applied to φ'cv tg ( fms = 1 ) .
2 . Stable circular slide (sliding surface analysis method) : analysis of sliding
surface method is used most commonly in circular sliding stability calculations
for embankment using reinforced embankment placed at the bottom . The torque
caused by the land sliding and load M
D
as :
(1.2)
M
RS
torque by keeping the land :
Torque remains enhanced by keeping M
RR
:

(1.4)
in which: ffs is the partial load factor of unit weight of soil ; wi : the weight of soil
column i ; bi : the ith soil column width ; αi : angle tangential bottom soil column
with the ith lateral Rd : radius circular slip ; fms : partial material factor applied to
tgφ'cv ; φ'cv : friction angle at the base construction material in large deformation
effective stress conditions ; ui : pore-water pressure effects on the ith sliding piece
Troj traction required for 1 meter long embankment at each point along the
bottom of the embankment j is defined as :

(1.5)
Among them : YJ ¬ arm is in the vertical direction of the torque to the dangerous
sliding surface at the center point on the bottom of the embankment j ; MRRj :
largest holding torque by strengthening core at point j on the bottom of
embankment ; MDJ : maximum torque slip at the bottom of the embankment j
(human factor has been) ; M


(1.8)
Among them : Svj gap remains vertical in slope at j ; Tj is the greatest traction in
the 1 m core length in slope at j ; ffs the partial load factor applied to the weight
unit volume of soil , hj is the height of the embankment on the slope j ; f
q
is the
partial load factor applied to the external load , ws is the external load due to
static load ( evenly distributed on the surface at structure [ 15 , p . 10 ] ) .
Paragraph anchor Lej not happen to slip reinforcement is determined from the
limit state vandalism , anchor length remains satisfied [ 15 , p . 118 ] .

(1.9)
Among them : L
ej
is reinforced anchor length minimum calculated at j ; fp : partial
factor control remains pulled slip phenomenon , fn : partial coefficient control
works damaged due cause ; fms : partial factor applied to tgφ'p and c ' , ws :
external load , α ' : interaction coefficient indicates the relationship between
power and ground anchor reinforced with tgφ'p ; φ'p : corner resistance biggest
cut of fill materials ; αbc ' : stickiness factor denotes an anchor link between soil
health - reinforced with c ' c ' : effective cohesion of the packing material .
Comment crease sliding surface method
- The method of calculating " wedge block two " not consider the effects of
horizontal thrust due to the inclination of the upper surface created ( only
considering the vertical force is the weight soil ) . " Block wedge two part " is a
general form of the limit equilibrium method . This method has the advantage of
simplicity , the present destructive potential can determine the approximate
gradually in a wide range . In addition, this method is also easy to set up a loop
calculation program on your computer. Crease sliding surface method is used in

q
: partial factor applied to the external load , Wi : weight of the ith soil column ;
Wsi : external load acting on the piece i c ' : unit cohesion of fill materials
identified in effective stress conditions , ui : pore water pressure exerted on the
sliding surface in pieces i ; φ'p : maximum shear angle of fill materials ; fms : the
partial material factor applied to tgφ'p and c ' ; : adjust the torque coefficient (
limit state damage taken by 1.25 , limit state obtained by using 1.0 ) .
In length it remains to be determined not undermining slip occurs remains is :
(1.14)
L
ej
is reinforced anchor length at least j in slope ; fp : partial coefficient to control
the core is pulled slip phenomenon , fn : partial coefficient to control the
economic consequences caused by damaged buildings cause ; fms : partial factor
applied to tgφ'p and c ' , ws : external load ( due to static load ) , α ' : interaction
coefficients indicate the relationship between power and ground anchor reinforced
with tgφ ' p ; φ'p : maximum shear angle of fill materials ; αbc ' : stickiness
coefficient indicates the relationship between soil anchor strength - reinforced
with c ' c ' : effective cohesion of the packing material .
Slip circle method was developed by [48] : K. Terzaghi , AV Bishop ; G.B. Janbu
; A.A. Nichiprovich ; Theory Method humidity .
Comment circular slide fragmentation methods : Method assuming stable sliding
- 8 -
surface with a radius R , are commonly used calculations to figure out the most
dangerous slip with a safety factor Fsmin . Slip circle method can calculate the
slope stability is generally different shapes , suitable only for homogeneous soil .
Essence reinforcing factors to be considered tensile strength Tmax .
c . Some other computational methods for reinforced embankments based on
equilibrium torque or force .
i . The method combined stress calculations [15] , [32] , [33] The destructive

: Pore water pressure effect on the ith sliding piece ; : torque correction
factor . The length of the anchor reinforcement is also determined by the formula
(1.14)
iii . Gravity method cohesion (Rankin) [15] , [35] , [63] This method of
calculation applied retaining wall is adjusted to calculate the slope remains the
case . In calculating principle applies two wedge blocks but adjusted to determine
how lateral pressure of the soil and the connecting points of greatest traction
corresponding to the tilt of the structure .
Comment analytic methods .
The analytical method based on limit equilibrium , embankment stability analysis
using assumed sliding surface : circular , with every crease assumed sliding
surface found a corresponding safety factor . So should identify numerous slip
surfaces with values different safety factor . Therefore, the ability to find the most
dangerous sliding surface with safety factor hardly accurate fit . Circular sliding
surface method is mainly applied to homogeneous background ; kinked slip
surface applied to multi-layered backgrounds , different physical properties . The
- 9 -
analytical method applied in the case of computational geometry embankment
sections normal , relatively simple . Not yet reviewed analytical methods to elastic
modulus ( E ) of land , land cover , and reinforcement material stiffness ( EA ) of
the reinforcement material in the background .
1.1.2.3 Numerical methods and computational software
1 . Method extreme Gauss principle and finite difference [8] extreme method
Gauss principle by GS . Prof. Ha Huy Cuong proposed , Hoang Dinh Dam
authors consider the problem in the absence of reinforcement layout and software
problems have reinforced horizontal . This problem is multi-layered elastic
system , relations between state suat_bien application form on the basis of elastic
theory for the case of plane strain problem . In the case of reinforced embankment
, to determine the state of stress - deformation of the embankment below the
horizontal reinforcing effects of vehicle weight ( distributed on a circle with a

tan c s


  
(1.19)
Among them : , and is the friction angle , unit cohesion and undrained cohesion of
the ground ; , and is the friction angle , cohesion and unit cohesion was not
impaired drainage of land background . The decline in value is calculated as
- 10 -

31
E
2sin

3
1-sin
2c cos
1-sin

1
follows
arctan
i
r
s
tan
F




with elastoplastic ground is ideal , the standard linear Mohr - Coulomb vandalism.
In fact , this relationship is complex includes several different stages according to
Robert M.Koerner model is presented in the next chapter . Therefore, in
calculating not realistically describe the material work .
Compared to other analytical methods mainly solved the problem of slope normal
shaped , circular slip surfaces , kinked hypothesis , based on the limit equilibrium
calculations taking into account the intensity geotextile ART but not considering
the elastic modulus (E) of land , the reinforcement material and stiffness (EA) of
the reinforcement material , the finite element method to calculate all kinds slope
different shapes , which consists of multiple layers embankment complex nature ,
the safety factor is defined as unique and single sliding surface based on the
consideration transferred in the element node . On the other hand , the finite
element method also include many factors affect the elastic modulus of the
ground , elastic modulus , hardness of structural reinforcement material in the soil
; Compared with organic difference method limit approximation problem by
differential equations , applicable only basic rectangular in shape with a simple
relationship , while finite element methods solve approximation results by word
solution of the problem , the background can be applied to any geometric shape
and have complex boundary problem in discrete relationships . From the
comparison presented above shows the finite element method has several
advantages compared to other methods .
1.2 These issues exist which thesis research will focus .
1 . The calculation methodology slope stability embankment with or without
reinforcement geotextile materials , commonly used analytical methods according
calculate equilibrium limit based on the assumption sliding circular , sliding
surface kinked hypothesis . However, numerous studies around the world show
that the slip surface is not sliding round and should be studied by the proposed
calculation methods [15] , [57] , [60] .
2 . Calculations embankment stabilization geotextile reinforcement method
- 11 -

model building problem embankment reinforcement geotextile material is
presented in the next chapter .
CHAPTER 2 COMPUTATIONAL MODELS OF GEOTEXTILE
REINFORCED EMBANKMENT PROBLEM .
2.1 Purpose and requirements .
2.1.1 Purpose : Selection , calculation model built using reinforced embankment
soft materials describes geotechnical realistic work of structural materials in the
system " soil - core " FEM method study the parameters affecting the stability
analysis and stress states - deformation of reinforced embankment
2.1.2 Requirement calculation model towards working closely with the actual
materials in structural system " + core land " was modeled and selection of
materials characteristic landforms, such that proper reinforcement case .
- 12 -
2.2 Properties of Geotextile [42] , [62] , [63] .
2.2.1 Some properties of the concept of geotextile [62] , [63]
Within the scope of this thesis , the hardness is not used in accordance with the
concept of bending stiffness hardness concept here is understood as : ( EA / L ) is
the stiffness of the unit element bearing axial bar , model chemical element
geotextile in finite element problems . And so EA is called the element stiffness
geotextile , unit is kN .
2.2.2 Road relations stress - deformation of the geotextile
According to the model of Robert M.Koerner in " Designing with Geosynthetics "
, 5th Edition, (USA, 2005) [63] , depending on the geotextile fabricating various
relationships that last curve behavior quite complex . Some types of geotextile
typical path ties stress - deformation characteristic is shown in figure 2.1 .

According to Robert M.Koerner , stress-strain relations of contact elements with
geotextile ground in a laboratory slide relations includes several phases : phase
nonlinear , 0 - 1 , increasing stress and deformation continued slow growth , the
period re- durable (hardened) - paragraphs 1-2 , to increased stress and

 
 
 
 
 
1
1
1
21
21
21
x x y z
y y x z
z z x y
xy xy
yz yz
zx zx
E
E
E
E
E
E
    
    
    





tan
S






:
i
r
F
c
c
S

and
,
,
ui
ur
F
s
s
S

(2.22)
Comment calculations by the finite element method taking into account many
factors characteristic of the ground and reinforcing materials such as elastic
modulus ground ; strength , elastic modulus , hardness reinforcement material .


(3.2)
3.1.2 Element level parametric triangular plates [18] , [24] , [64] Coordinates any
point in the element coordinates interpolated from nodes: .
1
1
n
e
i
i
N



,
1
n
e
ii
i
x x N



, and
1
n
e
ii
i


;
22
N


;
3 3 1 2
1N
  
   
(3.6)
The form function of triangular plate elements are nodes 6:
 
1 1 1
21N


;
 
2 2 2
21N


;
 
3 3 3
21N




  
( 3:13 )
The integral in Eq (3:13) can be done by using numerical integration are:
- 15 -
   
1
1
1
1 2 2 1 1 2
1
00
, 0.5 ,
n
i i i
i
f d d W f

     





(3:14)
3.1.3 Mohr - Coulomb model [ 33 ] , [ 54 ] , [ 59 ] , [ 64 ] Mohr - Coulomb model
is the first model included the effects of stress on the intensity of the ground . The
damage occurs when the stress states followed , normal stress on any plane of
material that satisfies the equation:
tan c

   

   

   

(3:26) Where:
0
0
n
s
k
D
k




(327)
D is called the elastic matrix , and k
n
; k
s
is the normal stiffness and tangential
Stiffness matrix of contact elements :
    
1
1
T
K B D B t J d


In that matrix deformation displacement relations in expression ( 3:28 ) takes the
following-form:
 
1 2 3 4
1 2 3 4
0 0 0 0
1
0 0 0 0
N N N N
B
N N N N
t






(3:35)
3.1.4.2 The nonlinear model of contact between the land and VDKT : stress-strain
relationship of the contact elements are often assumed to be ideal elastic plastic
Mohr - Coulomb . However, the actual behavior of the contact between the
geotextile and soil includes several stages as non-linear , re durable and soft goods
. Therefore , depending on the degree of contact between deformation and
geotextile - soil that stress exposure status is different in construction algorithm
- 16 -
calculates loop characteristic way relationship stress - deformation characterized
the relationship as shown in Figure 2.2 .
3.1.5 Geotextile Element .

- 17 -
Hnh_ress program was built by the
finite element method calculation
problem geotextile reinforced
embankment . In this stress-strain
relationship of geotextile are Robert M
Koerner model - described working
closely with the local reality of the
ground fabric . Calculation of
geotextile jet curve behaves as follows :
Jet geotextile in the calculation of load
balancing at each step of the iterative
solution of finite element method is determined by the power curve behavior -
displacement . This curve is constructed from samples geotextile experimental
results ( as shown in the form 3.16 ) . In the first step to finding solutions is the
initial displacement of the system , the stiffness of geotextile to build the stiffness
matrix is the slope of the first straight line from the origin ( if the behavior is
approximately equal to the line segment ) or tangent of the curve ( if the road is
approximately equal to the curve behavior ) at the origin of Ki . After each step
solution , displacement of geotextile be determined Uj and thus determine the
actual jet geotextile was defined as Tj . Secant stiffness is also determined by the
expression : Ktj = Tj / Uj (3.43).
In addition, the program features hnh_ress V1.00 has also established algorithms
to draw lines connecting points shear strain has the largest shear strain in
embankment ( Display > Slip Surface stresses ) , and calculate the sliding surface
to approximately result in the most appropriate form of sliding surface ( Report >
slip line) . Methods and results slip surface approximation is presented in later
chapters . Details of the program are presented in appendix 3 .
Conclusion Chapter 3 : The program geotextile reinforced embankment
HNH_RESS V1.00 software programs are calculated by the finite element

3
)
C (kN/m
2
)
φ (
0
)
E (kN/m
2
)
Embankment
6, 8, 10, 12
17.0
15
20
10000
Foudation
-
17.0
20
25
50000
Table 4.2 Characteristics of geotextile under 1m width
T
max
(kN/m)
E (kN/m
2
)

15,5
2
2
300
10
6,6
14,3
35,7
3
2
800
10
4,5
35,5
88,75
4.1.2 Analysis of embankment stability: hardness and strength of geotextile
relations with each other through elastic deformation characteristic limits:
max
e
T
EA


(4.4)
4.1.2.1 High embankment 6m
Table 4.4 safety factor of slope
High embankment
factor of slope
Layer number
Distance (m)

0
1,07
8
1/1
2
0,5
1,12
8
1/1
3
0,5
1,17
8
1/1
4
0,5
1,21
8
1/1
2
0,3
1,11
8
1/1
3
0,3
1,15
8
1/1
4

1,0
1,27
8
1/1
3
1,5
1,24
8
1/1
4
1,5
1,34
8
1/1
3
2,0
1,27
8
1/1
4
2,0
1,27
2. Determine the tension of geotextile work in embankment
Table 4.6 tension in the geotextile slope vandalized
3. Effect of slope coefficients to the safety factor of slope
Table 4.7 Effect of slope coefficients
High
embankment
(m)
factor of slope

7
0,4
1,22
16
1/1
6
0,4
1,21
- 20 -
18
1/1
5
0,4
1,19
20
1/1
5
0,4
1,20
22
1/1
5
0,4
1,22
24
1/1
4
0,4
1,20
26

Figure 4.10 The relationship between the
intensity and number of geotextile layers
slope coefficients 01/01/25
- 21 -
4.2 The embankment on soft soil 4.3 Identify types of slope slip under the sliding surface approximation method
4.3.1 Method approximately sliding surface (Figure 4.16)
4.3.2 Some examples of shear strain and route calculation is approximately
determined by the form of the slip surface hnh_ress program V1.00

Figure 4:23 approximated result slip surface 12m high embankment, slope 6m on
1/1, 5 and 6 m below the slope 1/1, 5, non-geotextile reinforcement
Some analytical results on record at 4:23 the following table: Figure 4.11 The relationship between the intensity and number of geotextile
layers, the slope coefficient 1/1.5
Figure 4:15 Elipse shaped slip
embankment on soft soil
Figure 4.16 sliding surface approximation
method