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http://www.iaeme.com/IJCIET/index.asp 871 [email protected]
International Journal of Civil Engineering and Technology (IJCIET) Volume 9, Issue 12, December 2018, pp. 871-880, Article ID: IJCIET_09_12_090
Available online at http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=9&IType=12
ISSN Print: 0976-6308 and ISSN Online: 0976-6316
© IAEME Publication Scopus Indexed
THE REASONABLE CROSS-SECTION SHAPE
FOR THE TUNNEL FROM HANOI METRO
SYSTEM UNDER THE IMPACT OF THE
EARTHQUAKES
Gospodarikov Alexandr
Saint Petersburg Mining University, Saint Petersburg, Russia Federation
Thanh Nguyen Chi
Saint Petersburg Mining University, Saint Petersburg, Russia Federation
Hanoi University of Mining and Geology, Hanoi, Vietnam
ABSTRACT
The metro system has become an important part of the infrastructure of major cities
in the world. Hanoi is the capital of Vietnam, where has got very many people (there
are about 8 million people) and there are important works here. At present, the metro
system that has been designed and built in Hanoi. Hanoi is located near Song La - Dien
Bien fault and Red River fault with the strongest earthquake that has magnitude MW =
6.5 Richter. This paper presents the impact of the earthquake that has the strongest
magnitude that can affect to the tunnel of Hanoi metro system with the different cross-
sectional shapes of the tunnel (including circles, squares, and horseshoes). Based on
the results, the paper will comment and provide a choice of cross-sectional profiles
suitable for the tunnel from Hanoi metro system when the tunnel works under the impact
of earthquakes.
Key words: earthquake; horseshoe; circular; square; impact; tunnel.
Cite this Article: Gospodarikov Alexandr and Thanh Nguyen Chi, the Reasonable
Cross-Section shape for the Tunnel from Hanoi Metro System under the Impact of the
Earthquakes, International Journal of Civil Engineering and Technology, 9(12), 2018,
pp. 871–880
http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=9&IType=12
1. INTRODUCTION
At present, there are many types of tunnel cross sections used in design and construction. Each
of the cross-sectional shapes has different advantages and disadvantages and, when selected,
should be based on the advantages and disadvantages of these cross sections as well as on the
Gospodarikov Alexandr and Thanh Nguyen Chi
http://www.iaeme.com/IJCIET/index.asp 872 [email protected]
safety requirements of the tunnels. In this paper, the author mainly refers to the effect of
earthquakes on tunnel stability as the criterion for evaluating and selecting the right cross-
sectional shape for the tunnel. There are many methods of assessing the effects of earthquakes
on the tunnel including the methods of Wang (2003) [4], Penzien et al. (1998, 2000) [5, 9],
Oresten (2007) [5], Do NA (2014) [4, 5] with the circular tunnels, Wood (2004, 2005) [10, 11]
with the square tunnels. Based on the hydrogeological and geological conditions in the center
Hanoi, the paper used several methods to assess the impact of the strongest earthquake that that
can occur the area Hanoi and based on the results obtained select the appropriate cross-section
shape for the tunnel of Hanoi metro system in case of the tunnel lining is continuous.
2. CALCULATION METHODS
2.1. Method Wang [4, 5]
In 1993, Wang (1993) [4, 5] based on closed form solutions recommended by Peck et al,
proposed modified analytical equations in terms of axial force, bending moments and
displacements under external loading conditions. Wang [4, 5] given equations that be used to
calculation structural forces in the tunnel lining under seismic loading conditions.
In case full–slip at the soil–lining tunnel’s, bending moment M and forces normal T can be
written by Wang [4, 5]:
1 max
1cos 2(
6 (1 ) 4
ET K R
πγ θ
ν= ± +
+
(1)
2
1 max
1cos 2(
6 (1 ) 4
EM K R
πγ θ
ν= ± +
+
(2)
Where 1
12(1 )
2 5 6K
F
ν
ν
−=
+ − (3)
In case no-slip at the soil – the lining tunnel, only the normal forces T can be expressed by
Wang (1993) [4, 5]:
2 max
1cos 2(
2 (1 ) 4
ET K R
πγ θ
ν= ± +
+
(4)
Where
[ ]
[ ]
2
2
2
1(1 2 ) (1 2 ) (1 2 ) 2
215
(3 2 ) (1 2 ) 8 6 6 82
F C
K
F C C
ν ν ν
ν ν ν ν ν
− − − − − +
= +
− + − + − + + − (5)
( )21
(1 )(1 2 )
s
S
E RC
E t
ν
ν ν
−=
+ − (6)
2 3(1 )
6 (1 )
S
S S
E RF
E J
ν
ν
−=
+ (7)
2(1 )
EG
ν=
+ (8)
The Reasonable Cross-Section shape for the Tunnel from Hanoi Metro System under the Impact
of the Earthquakes
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In 2013, Kouretzis el al. (2013) [5] proposed an equation of the maximum bending moment
in lining tunnel under no slip condition when effect dynamic loading, this to improve the
Wang’s method.
2
3 4 max(2 2 )2
K
RM K K τ= ± − −
(9)
max max max maxV Gτ ρ= ± (10)
Where max
τ -the maximum free field seismic shear stress, max
ρ -density of the surround
ground, max
G -the maximum ground shear modulus, max
V -the peak seismic velocity due to shear
wave propagation.
[ ] [ ]3
(1 2 )(1 C)F 0.5(1 2 )C 21
(3 2 ) (1 2 )C 0.5(5 6 ) (1 2 )C (6 8 )K
F
ν ν
ν ν ν ν ν
− − − − += +
− + − + − − + − (11)
[ ] [ ]
[ ] [ ]4
1 (1 2 )C F 0.5(1 2 )C 2
(3 2 ) (1 2 )C 0.5(5 6 ) (1 2 )C (6 8 )K
F
ν ν
ν ν ν ν ν
+ − − − −=
− + − + − − + − (12)
Where K1-full–slip lining response coefficient; K2-no–slip lining response coefficient; F -
flexibility ratio of tunnel lining respectively; Es-Young’s modulus of tunnel lining respectively;
C-compressibility ratio of tunnel lining respectively; νs- Poisson’s ratio of tunnel lining
respectively; R-tunnel radius respectively; Js-inertia moment of tunnel lining per unit length of
the tunnel (per unit width); t-thickness of tunnel lining respectively; ν-Poisson’s ratio of ground
mass surrounding tunnel; E- Young’s modulus of ground mass surrounding tunnel; G-shear
modulus of ground mass surrounding tunnel; I-moment of inertia of the lining tunnel; γmax-
maximum free–field shear strain; θ-angle measured counter-clockwise from spring line on the
right
2.2. Penzien’s Method [9]
Penzien et al. (1998, 2000) [4, 5, 9] developed similar analytical solutions for the thrust moment
and shear in tunnel lining. In Penzien’s method that has got two case of: the case of full-slip at
tunnel lining and soil layer surrounding and the case of no-slip condition. In case of full-slip
condition at the soil-lining, the normal forces T and bending moment M, that be defined by
equations:
3 2
12cos 2( )
(1 ) 4
n
s lining
S
E I dT
d
πθ
ν
∆= − +
− (13)
2 2
6cos 2( )
(1 ) 4
n
s lining
S
E I dM
d
πθ
ν
∆= − +
− (14)
3 2
24sin 2( )
(1 ) 4
n
s lining
S
E I dV
d
πθ
ν
∆= − +
− (15)
n n
lining free fieldd R d
−±∆ = ± ∆
(16)
4(1 )
1
n
nR
ν
α
−= ±
+ (17)
Gospodarikov Alexandr and Thanh Nguyen Chi
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3 2
12 (5 6 )
(1 )
n s
S
E I
d G
να
ν
−=
− (18)
In the case of no-slip condition between the tunnel lining and soil surrounding, the
formulations are presented as:
max
2lining free field
dd R d R
γ−
±∆ = ± ∆ = (19)
3 2
24cos 2( )
(1 ) 4
s lining
S
E I dT
d
πθ
ν
∆= − +
− (20)
2 2
6cos 2( )
(1 ) 4
s lining
S
E I dM
d
πθ
ν
∆= − +
− (21)
4(1 )
1R
ν
α
−= ±
+ (22)
3 2
24 (3 4 )
(1 )
s
S
E I
d G
να
ν
−=
− (23)
2.3. HRM Method [1, 4, 7]
Figure. 1 Calculation scheme of tunnel lining with the HRM method. σv: vertical load in the model
tunnel – surrounding ground; σh: horizontal load in the model tunnel – surrounding ground; kn: normal
stiffness of the interaction springs; ks: tangential stiffness of the interaction springs; R: tunnel radius;
EJ and EA: bending and normal stiffness of the tunnel lining [5, 8]
The Hyperstatic Reaction Method has been given by Duddeck and Erdmann [8], Takano
[4], Oreste [8]. Hyperstatic Reaction Method has content that is simulates the interaction
between the lining tunnel and environment material surrounding the tunnel lining by a number
of independent “Winkler” type springs [6]. In the Hyperstatic Reaction Method need to the
definition of the active loads that apply directly to the tunnel lining. In 2003, Mashimo and
Ishimura [5, 7] given different methods that be used to calculate for the active loads that apply
directly to the tunnel lining. When has got the effect of seismic loading, necessary to estimate
the active loads on the tunnel lining. Peinzen and Wu [5, 9] and Naggar et al. [2, 5] presented
R
EJ, EA
The Reasonable Cross-Section shape for the Tunnel from Hanoi Metro System under the Impact
of the Earthquakes
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equations, these can be used to the calculation of ovaling deformation of a circular tunnel
during a seismic due to the in-plane shear stresses caused by vertically propagating (notice that,
in case of the seismic load on the tunnel lining, all the external loads are rotated counter-
clockwise by 450 and the horizontal loads are in opposite directions). In this paper, the Matlab
program had used to the calculation for the internal forces on tunnel lining by Hyperstatic
Reaction Method.
2.4. Method Wood for the tunnel square
According Wang's method [5], Wood [5, 10, 11] had given the calculation method for the
rectangular tunnels. The content of Wood's method is defined by equations:
1
100
50 2
s s
s
s
HT T
G
ρ=
(24)
2
1
100
50 2
s s
s
s
Hu u
G
ρ=
(25)
1
s s
s
s
H
G
ρε ε=
(26)
si
ff
R∆
=∆
(27)
2
w
1
2 3 3241
2 2 (2 2 3 )
st
Hf
r jrP K
r j jr
∆= =
+ +−
+ + +
(28)
st
r
s
fF
f=
(29)
s
Hf
LG=
(30)
w6 (3 )
(2 )(2 )f
K j qM
H j j q q
∆ +=
− + +
(31)
w6 (3 )(2 )
1(2 )(2 )
r
K j q qM
H j j q q
∆ + += +
− + +
(32)
Where w
w
EIK
H= ; w
w
EIK
H= ; r
r
EIK
H= ;
w
rK
rK
= ; w1
r
Kq
r K= = ; E is Young’s modulus for
the structure material and Iw and Ir , If are the moments of inertia per unit length of the wall,
roof and floor respectively; Ts, us, εs , Gs are period, displacement strain and shear modulus of
soil layer; T1, u1 and ε1 are the reference soil layer values; sρ is soil density; G is shear modulus
in the soil at the level under consideration; fst is elastic flexibility of lining; R is the shear strain
deformation ratio; Fr is the flexibility ratio; Kw is wall stiffness; Kr is roof stiffness; Kf is floor
stiffness; q is ratio wall/roof stiffness; j is ratio floor/roof stiffness; r is ratio roof/wall stiffness;
Gospodarikov Alexandr and Thanh Nguyen Chi
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Mr is the moment at the top corner of structure; Mf is the moment at the bottom corner of
structure.
2.5. 2D numerical method
There are three tunnel models produced by the 2D numerical method using Abaqus software,
including the tunnel model with the cross-section of tunnel is circular with radius R = 3.15 m,
the tunnel model cross-section is square with a size of 5.5mx5.5m and a tunnel model with the
cross-section is horseshoe-shaped with the radius of the dome R and the height of the column-
wall h, R=h=2.95 m. In this method, the case study is no-slip at the tunnel lining with soil and
regardless of the effect of gravity and groundwater conditions. These models are divided into
two zones. The stages of this method include:
- Phase 1. Setup the tunnel model, tunnel lining and soil layer surrounding with their
parameters;
- Phase 2. Setup boundary conditions, setting up the pressure on the tunnel lining and
model's boundary, assign to the peak ground acceleration of the earthquakes to the model with
layer soil by link conditions;
- Phase 3. Give the effects of earthquakes on the tunnel models and present the results
obtained of the models.
Note. The layered soil surrounding tunnel is elastic.
3. CALCULATION FOR THE TUNNEL LINING FROM HANOI
METRO SYSTEM
3.1. Characteristics of earthquakes, soil and tunnel in Hanoi metro system
The hydrogeological and geological conditions of Hanoi center these are as follows: the
groundwater level is three meters below the surface; the distance from the ground surface to
the bedrock is 48-50 m and there are usually six layers of soils in Hanoi center.
The characteristics of the tunnel of the Hanoi metro system in Hanoi center [3, 5]: The
tunnels were a depth of between 15 and 20m below the ground surface. The tunnel lining is
made reinforced concrete with characteristics are: El = 35500 MPa; Poisson’s ratio νl = 0.15;
Lining thickness tl = 0.35 m.
The strongest earthquakes that can occur in the Hanoi center that have characteristics [4,
5]: highest magnitude MW=6.5 Richter; distance from the epicenter of the earthquake to Hanoi
is 20 to 50 km and peak ground acceleration amax=0.2g.
Table 1 The properties of the soil in Hanoi Centre [3, 4, 5]
Number
of soil
layers
Elastic
module, E,
MPa
Poisson’s
ratio, µ Thickness of
layer (d), m
Measured SPT
blow count, N
Density of the
soil, ρ, g/cm3
1 9.25 0.41 4.6 2 1.75
2 7.68 0.38 1.1 1 1.76
3 15.3 0.35 11.8 3 1.81
4 35.02 0.33 12.5 7 1.78
5 53.9 0.32 11.0 10 1.83
6 65 0.3 7.0 12 1.86
The Reasonable Cross-Section shape for the Tunnel from Hanoi Metro System under the Impact
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Figure 2 Data of El Centro earthquake [5]
3.2. Results and Discussions
In case of the circular tunnel [4, 5, 6]:
Figure 3 Result calculation of model tunnel’s by 2D numerical method [4, 6 ]
Figure 4 State stress on the tunnel lining in 2D numerical method [4, 6]
Figure 5 Strain of the tunnel lining in 2D numerical method [4, 6]
-0.25
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
0.25
0.000 5.000 10.000 15.000 20.000 25.000 30.000 35.000
Acc
eler
atio
n,
g
Time, s
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Figure 6 Bending Moment M and Normal force T in the lining tunnel by HRM [4, 6]
Table 2 Summary of analysis results
The internal forces in lining tunnel HRM method 2D numerical method
M (kN.m/m) 106.64 -
T (kN/m) 190.34 -
σ (MPa) 5.771 4.213
Figure 7 State stress on the square tunnel lining and the horseshoe tunnel lining by 2D numerical
method
Figure 8 State stress on the square tunnel lining and the horseshoe tunnel lining by 2D numerical
method
-150
-100
-50
0
50
100
150
0 60 120 180 240 300 360
Ben
din
g M
om
ent
M (
kN
m/m
)
θ (degree)
0
20
40
60
80
100
120
140
160
180
200
0 60 120 180 240 300 360
No
rmal
fo
rce
T (
kN
/m)
θ (degree)
The Reasonable Cross-Section shape for the Tunnel from Hanoi Metro System under the Impact
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Figure 9 Strain of the square tunnel lining and the horseshoe tunnel lining by 2D numerical method
Table 3 Analysis results of calculation 2D numerical method for the different tunnel models
Tunnel cross-sectional shape
Stress on the
tunnel lining
(MPa)
Difference with the
reference (%)
The circular tunnel (reference case) 5.721 -
The square tunnel 6.912 20.818
The horseshoe tunnel 15.23 171.281
Based to the results in Table 2 and Figures 3, 4, 5, 6. In case of the circular tunnel, under
the impact of the strongest earthquake that can occur in the Hanoi center by use to 2D numerical
method with Abaqus program then a difference between the maximum stress value on the
tunnel lining with the maximum stress value in the tunnel lining of the Hyperstatic Reaction
Method is 5.799%, this difference is not large and can conclude about the accuracy of the
Hyperstatic Reaction Method when this method was used for the circular tunnel. With the
results obtained in Figures 7, 8, 9 and in Table 3, it is possible to give the following conclusions:
The stress values appearing in the tunnel lining under the influence of the strongest earthquakes
that can affect the Hanoi center in the case of the tunnels have different cross-sectional shape
with very large differences. By selecting the circular tunnel that is the reference case, the
difference in stress on the tunnel lining when the tunnel cross-section is square with the
standard case is 20.818% The difference in stress on the tunnel lining when the tunnel has
horseshoe cross-section with the reference case is 171.281%.
4. CONCLUSION
In this paper, tunnel models with different cross-sectional shapes have been constructed
together with the properties of tunnel lining and surrounding environments. Using the 2D
numerical method with Abaqus software and the Hyperstatic Reaction Method, the paper
presents the internal forces that appear on the lining of tunnel models when these tunnels work
under the influence of the strongest magnitude earthquake that can affect the Hanoi center. This
paper studied and compared the internal forces results obtained on the tunnel lining in each
case and given the following conclusions:
1. In all case studies: the circular tunnel, the square tunnel, and the horseshoes tunnel,
tunnels from the metro system of Hanoi operate stably under the influence of the strongest
magnitude earthquake that can affect the Hanoi-the maximum value stress occurring on the
tunnel lining under the impact of the strongest earthquake that can affect Hanoi (maximumσ =
15.281 MPa) is less than the limited stress value of material tunnel’s ( limitσ = 22 Mpa);
2. In three cases of the cross-sectional shape of the tunnel that has been studied, including
circles, squares and horseshoes, under the effect of the same earthquake, the maximum value
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stress appeared on the circular tunnel lining is the smallest value stress appeared on the tunnel
lining in three cases ( maximumσ = 5.72 MPa), the stress for the case of a tunnel whose cross-
section is square has a value of maximumσ = 6.912 MPa, and the maximum stress occurs on the
horse-shaped tunnel lining that is the greatest value stress in three cases of maximumσ = 15.281
MPa. From this result, it is possible to select the reasonable shape of the tunnel from the Hanoi
metro system when the tunnel has been affected by the earthquake that is the circular tunnel.
ACKNOWLEDGEMENTS
This work was supported by the Saint Petersburg Mining University. We thank two anonymous
reviewers for their comments that were very valuable for revising the manuscript.
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