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Noi Bai International Airport to Nhat Tan Bridge Connecting Road Construction Project
Stage: Working drawing Package 2: Km1+539.48 -:- Km3+943.00
Conten ts
1. Introduction
2. Legal basic for implementation
3. Standard used
4. Highway raute composition of geological layers and condition
5. Design criteria
6. Calculation methodology
7. Summary of Soil Value for Soft Soil Treatment Design
8. Soft soil treatment analysis
9. Result of soft soil treatment embankment
1. Introduction 2
5.1 Settleme n t and C on solida t ion . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5.2 S tabilit y again st sliding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5.3 T raffic lo ad . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
6. Calculation methodology 7
6.1 T h eory a n d Calcu lation fo r Vertical Drai n . . . . . . . . . . . . 7
6.2 S oftware . . . . . . . . . . . . . . . . . . . . . . . 11
1
Noi Bai International Airport to Nhat Tan Bridge Connecting Road Construction Project
Stage: Working drawing Package 2: Km1+539.48 -:- Km3+943.00
Noi Ba i internat ional a irport to Nhat T an brid ge
connect ing ro a d const ruction p roject
S t a g e : w or k i n g d r a w i n g s
PACKA G E 2: Km 1+539.4 8 -:- K m3+943.0 0
Report on sof t so il treat ment
1. Introduction
Nhat Tan Bridge to Noi Bai Airport connecting road construction project is priority
project, which was received interests of Government, Ministry of Transport and Ha
Noi people’s Committee. Starting point of the project is intersection between approach

road of Nhat Tan Bridge project and Nam Hong road in Van Noi commune, Dong Anh
district. The Ending point is conjunction road to T2 Station of Noi Bai Airport in Soc
Son district, Ha Noi Capital.
Features package 2:
Construction location: Dong Anh, Ha Noi
Beginning: Km1+539.48 The retaining wall abutment A10 of railway bridge over, endpoint
package 1.
Endpoint: Km3+943.00 The retaining wall abutment A0 Ca Lo bridge.
The total length: L = 2403.52m.
2. Legal basic for implementation
- Decree No. 12/2009/NĐ-CP dated 12/02/2009 issued by the Government regarding
structure construction management ;
- Circular No. 03/2009/TT-BXD dated 26/3/2009 by the Government regarding
regulating details of some agenda of Decree No. 12/2009/NĐ-CP dated 12/02/2009
regarding structure construction investment project ;
- Pursuant to the Government Decree No. 34/2003/NĐ-CP dated 04 April, 2003
stipulating the functions , tasks, powers and organizational structure of the Ministry of
Transport;
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Noi Bai International Airport to Nhat Tan Bridge Connecting Road Construction Project
Stage: Working drawing Package 2: Km1+539.48 -:- Km3+943.00
- Pursuant to the Government Decree No. 16/2005/NĐ-CP dated 07 February, 2005 on
management and investment for construction of work and the Government Decree No;
1612/2005/NĐ-CP dated 29 June, 2006 on adjustment to some clauses of the Decree
No. 131/2006/NĐ-CP dated 07. February, 2005;
- Pursuant to the Government Decree No. 131/2006/NĐ-CP dated 09 November, 2006
stipulating Regulation on managing and using source of official development
assistance;
- Pursuant to the Government Decree No. 209/2004/NĐ-CP dated 16 December, 2004
on construction work quality management;

- Pursuant to the Government Decree No. 99/2007/NĐ-CP dated 13 June, 2007 on
managing investment for construction of work;
- Pursuant to the Government Decree No. 78/2007/NĐ-CP dated 11/05/2007 on
Investment of Building - Operation - Transfer; Building - Transfer - Operation;
Building - Transfer;
- Pursuant to the Government Decree No. 162/2002/QĐ-TTg dated 15/11/2004 of
Prime Ministry on validation of Viet Nam Highway Traffic development and planning
updating to 2010 and direction to 2020;
- Pursuant to the Government Decree No. 206/2004 QĐ-TTg dated 10/12/2004 of
Prime Ministry on validation of development strategy for Transport updating to 2020;
- Pursuant to the decision of Ministry of Transport No. 252/QĐ-BGTVT dated
25/01/2008 on Feasibility study for Nhat Tan bridge to Noi Bai Airport connecting
road construction project;
- Pursuant to the decision of Ministry of Transport No.3996/QĐ-BGTVT dated
31/12/2008 on validation of investment in construction of Nhat Tan bridge to Noi Bai
Airport connecting road construction project - Sub-project1(Km00+000) to
(Km7+850);
- Geological survey method for shop drawings consultation has been approved by letter
SC-CTI/K-0020A, dated 13 june 2012.
- Project's survey techniques request.
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Noi Bai International Airport to Nhat Tan Bridge Connecting Road Construction Project
Stage: Working drawing Package 2: Km1+539.48 -:- Km3+943.00
3. Standard used
No Standards/Procedure Code/date Remarks
1 Exploratory boring procedure 22TCN259-2000 Viet Nam
2 Term of reference for soft soil investigation for
prepering of shop drawing of the package 1A
3 Specification for survey and design of highway
embankment on soft ground are

22TCN262-2000 Viet Nam
4. Highway raute composition of geological layers and condition
4.1. Layer DR: Farm land.
This layer was encountered from surface, the thickness of sub-layer change from
0.50m to 0.70m.
4.2. Sub- layer 2a: Yellowish grey, Brownish grey, whitest grey, stiff to very stiff,
Clay.
It was encountered in BSDY1, BSDY2 and BSTC1 borehole with the top elevation is
from 5.23m to 9.77m and from 3.30 to 6.90m of thickness. The N value of SPT varies
from from 12 to 17.
Covention bearing capacity R = 1.70 kG/cm
2
4.3. Sub- layer 4b: Brownish grey, soft to medium stiff, Sandy clay.
It was encountered in BSDY1, BSDY2 and BSTC1 (working drawing) with the top
elevation is from 1.43m to 2.87m and from 5.20m to 8.00m of thickness. The N value
of SPT varies from 4 to 8.
4.4. Layer 5: Greenish grey, brownish grey, loose, clayey sand.
It was encountered in BSTC1 (working drawing) hole with the top elevation is -2.33m
and 6.80m of thickness. The N value of SPT varies from 7 to 9.
Convention bearing capacity R = 1.25 kG/cm
2
4.5. Sub - layer 6b: Greenish grey, medium dense, small sand.
It was encountered in BSDY1 and BSDY2 (working drawing) hole with the top
elevation is from -6.031m to -3.97 and from 7.00 to 7.60m of thickness. The N value
of SPT varies from 11 to 15.
Convention bearing capacity R = 1.50 kG/cm
2
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Noi Bai International Airport to Nhat Tan Bridge Connecting Road Construction Project
Stage: Working drawing Package 2: Km1+539.48 -:- Km3+943.00

4.6. Sub - layer 8a: Brownish grey, greenish grey, Medium stiff - stiff, Clay.
It was encountered in BSDY1, BSDY2, and BSTC1 (working drawing) holes with the
top elevation is from -13.031m to -9.13m and from 1.20m to 7.60m of thickness. The
N value of SPT varies from 7 to 14.
Convention bearing capacity R < 1.00 kG/cm
2
4.7. Sub - layer 11b: Whitest grey, very dense, Coarse sand with gravel.
It was encountered in BSTC1 (working drawing) holes with the top elevation is
-16.73m and 0.50m of thickness. The N value of SPT is 51.
Convention bearing capacity R = 4.50 kG/cm
2
(under the table standards 22TCN260-
2000).
4.8. Layer 12: Whitest grey, yellowish grey, Very dense, Gravel.
This layer was encountered in BSTC1 holes.The elevation of layer top is -17.23m, the
thickness of layer was not defined yet, the maximum thickness, which was drilled into
layer is 4.60m (BSTC1). The N value of SPT is more than 50.
Convention bearing capacity R = 8.00 kG/cm
2
(under the table standards 22TCN260-
2000).
5. Design criteria
The following standards shall be recommended to apply for soft soil treatment design:
- Standard for Investigation and Design of Embankment on Soft Ground 22TCN262-
2000,
- Expressway – Requirement for Design TCVN5729-1997.
Pursuant to the above Standard, followings are criteria for soft soil treatment design:
5.1 Settlement and Consolidation
Soft ground shall be treated to ensure both conditions as depicted below (22TCN262-2000-
II.2.3):

- Residual settlement (Sr) is less than: 10cm for approach sections, 20cm for culvert and
under passing sections, and 30cm for other sections.
- Highway under class 60 with surfacing class A: 20cm for approach sections, 30cm for
culvert and under passing sections, and 40cm for other sections
- Consolidation degree is not less than 90% or speed of residual settlement is less than
2cm per year (TCVN5729-97-8.10.2).
5.2 Stability against sliding
Following conditions shall be confirmed for stability against sliding:
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Noi Bai International Airport to Nhat Tan Bridge Connecting Road Construction Project
Stage: Working drawing Package 2: Km1+539.48 -:- Km3+943.00
- Factor of safety is not less than 1.2 in period of filling and waiting for consolidation,
and
- Factor of safety is not less than 1.4 at the end of final period of waiting for
consolidation.
5.3 Traffic load.
Traffic load is evaluated in accordance with 22TCN262-2000 from following equations:
lB
Gn
q
×
×
=
(1-1)
( )
ednbnB +×−+×= 1
(1-2)
Where as (see Figure 1-1)
n: Number of vehicle,
G: Weight of vehicle (=30 ton in case of H30),

B: Width of traffic load (Max. 14.3m as designated, 1 side),
l: distance between front wheel and rear wheel (=6.6m, in case of H30),
b = 1.8 m, e = 0.5m, d = 1.3m
Results: q=1.59 t/m
2
and will be distributed in the carriage ways as sketched for calculation as
figure 1-2.
l
e /2
b
b
d
e /2
B
Figure 1-1 Traffic load calculation diagram
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Noi Bai International Airport to Nhat Tan Bridge Connecting Road Construction Project
Stage: Working drawing Package 2: Km1+539.48 -:- Km3+943.00
Figure 1-2 Traffic load value and distribution
6. Calculation methodology
6.1 Theory and Calculation for Vertical Drain
a) Settlement
Due to variation of stress caused by embankment load by distribution depth of soil, a soil
layer will be divided into sub-layers for settlement calculation and settlement of the soil layer
will be summed up from the settlement of the sub-layers.
It is possible to calculate consolidation settlement by using original formula as depicted below
(hereinafter referred to as
∆
e method):
H

e
ee
S
o
c
0
1
1 +
−
=
(2-1)
Or the following modified formulas (hereinafter referred to as Pc/Cc method):
0
0
0
log
1 P
PP
H
e
C
S
c
c
∆+
+
=
For normal consolidation (2-2)
o
o

o
s
c
P
PP
H
e
C
S
∆+
+
= log
1
For over consolidation and P
c
>P
0
+
∆
P (2-3)
c
cc
o
s
c
P
PP
H
e
C

P
P
H
e
C
S
∆+
+
+
+
=
0
00
log
1
log
1
For overconsolidation and P
c
<P
0
+
∆
P (2-4)
In the sand layer, the following formula can be used for immediately settlement (De Beer
method)
o
o
i
P

PP
H
N
P
S
∆+
=
0
log4.0
(2-5)
1m
As designed
1.5m 1m
q=1.54 t/m
2
q=1.54 t/m
2
1.5m
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Noi Bai International Airport to Nhat Tan Bridge Connecting Road Construction Project
Stage: Working drawing Package 2: Km1+539.48 -:- Km3+943.00
Where as:
Sc: Consolidation settlement,
Si: Immediately settlement of sandy soil layer,
e
o
: Void ratio at pressure of P
0
(Initial void ratio),
e

1
: Void ratio at pressure of P
0
+
∆
P,
P
0
: Overburden pressure,
∆
P: Pressure caused by embankment,
Cc: Compression index,
Cs: Swell index,
Pc: Pre-consolidation pressure,
H: Soil thickness.
N: Standard penetration test value
b) Consolidation
In case of no vertical drain, time factor (T
v
) will be calculated from formulas (2-6) as follow:
2
H
Cvt
T
v
×
=
(2-6)
Then consolidation degree will be computed by Terzaghi U
v

– T
v
relationship as follow:
2
1004






×=
U
T
v
π
in case 0<U<53% (2-7)
( )
UT
v
−×−= 100log933.0781.1
in case U>53% (2-8)
Where as
t: Settlement time,
H: Drainage distance,
Tv: Time factor,
Uv: Consolidation degree,
Cv: Coefficient of Consolidation.
In case such vertical drain as PVD, sand drain, etc. are installed for soft soil treatment,
consolidation degree will be evaluated from Carrillo expression:

( ) ( )
hv
UUU −−−= 1*11
(2-9)
Where as:
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Noi Bai International Airport to Nhat Tan Bridge Connecting Road Construction Project
Stage: Working drawing Package 2: Km1+539.48 -:- Km3+943.00
U: Consolidation degree,
U
v
: Vertical component of consolidation being computed as mentioned above,
U
h
: Horizontal component of consolidation being computed from Hansbo
recommendations as follow:






×−
−=
F
T
U
h
h
8

exp1
(2-10)
2
.
e
h
h
d
tC
T =
(2-11)
rs
FFnFF ++= )(
(2-12)
2
2
2
2
4
13
ln
1
)(
n
n
n
n
n
nF
−

−
−
=
(2-13)
w
e
d
d
n =
(2-14)
















−=
w
s
s

h
s
d
d
k
k
F ln1
(2-15)
( )
w
h
r
q
k
zLzF −= 2
π
(2-16)
Where as:
T
h
: Time factor,
C
h
: Horizontal consolidation coefficient,
d
e
: Effective drainage distance (=1.13d
s
for square pattern, =1.05d
s

for triangular
pattern),
d
s
: Center to center spacing between vertical drain units,
d
w
: Diameter/equivalent diameter of vertical drain unit,
k
h:
Horizontal permeability,
k
s:
Permeability in smear zone,
d
s
: Diameter of smear zone in cross section,
L: Drainage length,
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Noi Bai International Airport to Nhat Tan Bridge Connecting Road Construction Project
Stage: Working drawing Package 2: Km1+539.48 -:- Km3+943.00
q
w
: Discharge capacity of vertical drain unit.
c) Shear strength due to consolidation
Undrain shear strength of soft soil is considered to increase for an amount of
∆
C due to
consolidation being evaluated as follow:
( )

mUPPPC
c
××∆+−=∆
0
(2-24)
Where as:
∆
C: Increased amount of undrain shear strength due to consolidation,
m: Index of increase of undrain shear strength.
m = tg
ϕ
CU
(Show in table 3-1)
d) Sliding check
Bishop method as formulated below is recommended for sliding check.
( )
[ ]
∑
∑
×−+×
=
α
ϕ
sin
tan
1
w
buwbC
m
Fs

a
(2-25)






+=
Fs
m
a
ϕ
αα
tan
tan1cos
(2-26)
Where as (see figure 2-2):
C: Cohesion,
ϕ
: Internal friction angle,
b: Width of slice,
u: Pore water pressure acting at the slice base,
W: Weight of slice,
α
: Slice base angle to the horizontal direction.
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Noi Bai International Airport to Nhat Tan Bridge Connecting Road Construction Project
Stage: Working drawing Package 2: Km1+539.48 -:- Km3+943.00
α

Figure 2-2 Sliding check model
6.2 Software
All calculation has been computed with assistance of software: Microsoft Exell for calculation
of settlement and consolidation, and Geoslope for sliding check.
7. Summary of Soil Value for Soft Soil Treatment Design
According to laboratory testing, values of the soil recommended for soft soil treatment design
are summarized in the following table 3-2.
Table 7-1. Summary of Soil Parameters Recommended for Soft Soil Treatment Design
Layer soil
γ
o
ε
o
Pc OCR Cc Cs Cv
KN/m
3
KN/m
2
10
-4
cm
2
/s
Borrow material
18.50 30
o
00’ 0.00
3b 18.80 0.832 12.60;
11.60
1 0.235;

0.600
0.044;
0.100
28.7 2 30
4b 18.40 0.926 9.90 >1 0.290;
0.600
0.032;
0.109
33.6 2 18.0 0.25
6b 18.50 0.656 24
o
00’ 0.00
8. Soft soil treatment analysis
8.1. Summary of result no treatmeant
Please see result of settlement and stability embankment.
8.2. Method of treatment
In the section, method of treatment as follows:
SD (Distance d = 1.80m, depth D = 12.00m, Diameter
Φ
= 40cm).
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Noi Bai International Airport to Nhat Tan Bridge Connecting Road Construction Project
Stage: Working drawing Package 2: Km1+539.48 -:- Km3+943.00
9. Result of soft soil treatment embankment
Please see result of settlement and stability embankment.
12