EURO:TUN 2013
3rd International Conference on
Computational Methods in Tunneling and Subsurface Engineering
Ruhr University Bochum, 17-19 April 2013

In-situ Measurement and Numerical Analysis on Tunnel
Lining and Ground Behaviour due to Shield Excavation
Takahiro Konda1, Junichi Nagaya1, Tadashi Hashimoto1,
Hossain M. Shahin2 and Teruo Nakai2
1
Geo-Research Institute, Japan
2
Nagoya Institute of Technology, Japan
Abstract
In urban tunnelling, often construction is done under some constrained conditions. In
this paper, the ground movement due to shield excavation is observed and somemeasurements of the first tunnel lining pressure and stress development due to the
excavation of second shield tunnel close to the first tunnel are carried out. The
influence of the construction loads due to shield tunnelling on the surrounding groundand nearby structures is discussed. Numerical analysis is also carried out with elastoplastic constitutive model of soil in which the mechanical characteristic of groundmaterial and the construction process are appropriately taken into consideration.
Comparing the results of the analyses with the monitoring data, the behaviour ofsurrounding ground and existing structure due to shield excavation is investigatedfocusing on the influence of the construction loads. The finite element analyses arecarried out with FEM tij-2D software using an elasto-plastic constitutive model ofsoils, named subloading tij model. It is revealed that during the construction of thefollowing tunnel loads acted on the lining of the preceding tunnel. The elasto-plastic
FE analysis is able to explain these actual behaviours adequately that cannot be
expressed by the analysis using the conventional stress release ratio.
Keywords: Shield tunnel, monitoring, numerical analysis, subloading tij model, construction load

191

Takahiro Konda, Junichi Nagaya, Tadashi Hashimoto, Hossain M. Shahin and Teruo Nakai

1

INTRODUCTION

In urban shield tunnelling, often construction is done at about 1m distance under someconstrained conditions such as the limitation of the road width and the existence of
the underground structures. In these neighbouring constructions, it is necessary toevaluate the influence and assess the safety of surrounding ground and existing
structure due to shield excavation adequately. The calculation method with stressreleased ratio is usually used in Japan to predict the ground behaviour due to shield
excavation. However, because ground movements are depended on someconstruction conditions, for example cutter face pressure, backfill grouting pressure,control position of shield machine and so on, ground deformation behaviours aredifferent each construction steps.
In this paper, the ground movement due to shield excavation is observed and somemeasurements of the first tunnel lining pressure and stress development due to the
excavation of second shield tunnel close to the first tunnel are carried out. The
influence of the construction loads due to shield tunnelling on the surrounding groundand nearby structures is discussed. Numerical analysis is also carried out with elastoplastic constitutive model of soil in which the mechanical characteristic of groundmaterial and the construction process are appropriately taken into consideration.
Comparing the results of the analyses with the monitoring data, the behaviour ofsurrounding ground and existing structure due to shield excavation is investigatedfocusing on the influence of the construction loads. The finite element analyses arecarried out with FEM tij-2D software using an elasto-plastic constitutive model ofsoils, named subloading tij model [2]. This constitutive model has already applied tosome braced excavation problems [1] and tunnel excavation problems [3], andcalculation results had good response to model test results.
2

SOILS CHARACTERISTICS AND CONSTRUCTION
CONDITIONS

Figure 1 show the soil profile and installation position of monitoring apparatus in thetarget construction site of shield excavation. The specifications of tunnel lining andexcavation conditions when the shield passes through the monitoring section are
shown in Table 1. The monitoring section was set at the area which is very close thesecond tunnel, where the second shield tunnel is obliquely upward of the first tunnel
with a distance of about 1,1m.

192

In situ Measurement and Numerical Analysis on Tunnel Lining and Ground Behaviour due to Shield Excavation

Holocene layer and Pleistocene layer exist from the ground surface to the place near
this monitoring site. Holocene layer is composed of a fine sandy layer (Aus), soft clay
layers (Amc1 and Amc2), a sand gravel layer (Amg) and a sandy layer with medium
density (As). On the other hand, Pleistocene layer exist in the lower part of
Holocene layer, and is composed of a stiff clay layers (Oc2), a dense gravel layer (Tg)and a dense sandy layer (Os2). Table 2 shows some characteristics of each layer.
The upper ground of the first tunnel is formed with Amc2 and Ams soft layers.
Meanwhile, hard layer Oc2 and Tg exist in the lower side ground of the first tunnel.
In contrast, dense sand gravel layer Amg exist in the upper ground of the second
tunnel, and soft clay layer Amc2 exists at the lower ground of the second tunnel.
The vertical displacement above the first tunnel and the horizontal displacement alongwith the vertical distance beside the first tunnel due to shield excavation aremeasured. Moreover, to evaluate the influence of the construction loads on the firsttunnel lining due to second shield excavation, first tunnel lining pressure and crosssection force are monitored.
3つの計測器設置位置は南行
シールド側部から1.0m離れ

5No.1 .67m+4
O.P.50.23m
Dep=

O.P.+5.0m

3720
0 10 20 30 40 50 60▽O.P.+4.67m

B

沖積砂層(As)
Aus

-5

15500

15500

0

下水φ3150

Amc(1)

2147

25000

沖積粘土層
(Ac)

沖積砂層(As)
洪積粘土層(Oc)

2000
500

Ams
Oc2

12
11

沖積粘土層
(Ac)

1000

▽O.P.-11.872m

Amc(2)-1531000

後行(北行)
シールド

1000

沖積砂礫層
(Ag)

Amg

2000

-10

先行(南行)
シールド▽O.P.-17.307m

-20

1000

12150

洪積砂礫層(Tg)

Tg

-25
Os2
計測器
：層別沈下計●●▲■：連通管式沈下計：多段式傾斜計：間隙水圧計：パッド式土圧計●

Stratified settlement gauge
Contimuance pipe type settlement gauge
Mutistage clinometer
Pore water pressure gauge
Pad type lining pressure gauge
strain gauge：ひずみ計

Figure 1:

Installation position of measurement equipment

193

Takahiro Konda, Junichi Nagaya, Tadashi Hashimoto, Hossain M. Shahin and Teruo Nakai

Table 1:

Specification of segments and shield excavation condition
1st tunnel

Shield excavate type
Outer diameter of shield / of tunnel lining(m)Tunnel lining type
Number of pieces
Young modulus E (kN/m2)
Ares A (m2)
Area moment of intertia (m4)Overburden pressure (kN/m2)
Planning value
Cutter face pressure(kN/m2)
Monitoring value
Planning value
Backfill grouting pressure
Driving
Monitoring2(kN/m )
value
Stopping
Area
Pitching (‰)
Average
Excavation line shape (vertical) (‰)
Over cut (mm)3

CALCULATION CONDITION

3.1

Constitutive Model of Soil

2nd tunnel
Slurry type5,44 / 5,30
Cast-iron segment (Width : 0,9 m/ring)
6 (A-type:3, B-type:2, Key:1)
1,7×107
0,02460,00013
340
240
245
185
190 － 280
170 － 190360
280
100 － 360
100 － 300
280 － 310－
-40,0 － -35,0-8,0 － -6,8
-35,5
-7,5
-33,0
-10,0
15

The finite element analyses have been carried out with FEM tij-2D software using anelasto-plastic constitutive model of soils, named subloading tij model. The constitutive
model requires a few soil parameters which can easily be obtained from conventional
laboratory tests data. This model can consider influence of intermediate principal
stress on the deformation and strength of soils, dependence of the direction of plastic
flow on the stress paths, influence of density and/or confining pressure on the
deformation and strength of soils.
3.2

Load Model considering Construction Loads

The considerable loading factor and the point of view of each construction stage aredenoted as follows, and the calculation model for each step is shown in Figure 2.
3.2.1

Load model at the arrival of cutter face

When the cutter face pressure is larger than the lateral pressure, thrust acts on the
ground consequently heaving occurs above the tunnel. In the reverse situation of thepressure balance, opposite phenomenon happens. Briefly, the ground deformation

194

In situ Measurement and Numerical Analysis on Tunnel Lining and Ground Behaviour due to Shield Excavation

behaviour depends on the balance between the cutter face pressure and the lateralpressure. In this paper, this influenced ratio is 15% of the differential pressure
between both pressures according to reference [4] is applied.
3.2.2

Load model at the first half of shield machine

The ground deformation in this stage significantly depends on the slurry pressure of
the cutter face in the additional void between the ground and the shield machine.
When the slurry pressure is smaller than the overburden pressure, the settlement
occurs just above the tunnel. However, because the slurry pressure is larger than thelateral pressure in the lateral direction, horizontal expansion occurs. Therefore,pressure at the cross section equals to the differential pressure between the cutters facepressure and the ground pressure around tunnel. Moreover, the self-weight of the firsthalf of shield machine without buoyancy force adds pressure on the cross section.
3.2.3

Load model at the second half of shield machine

It has been thought that the influence of backfill grouting pressure is dominant in the
ground deformation around tunnel in this stage. But in these monitoring results, thebackfill grouting pressure is smaller than the overburden pressure, and it is impossible
to heave the ground above the tunnel only by the backfill grouting pressure.
Investigating the shield excavation conditions in detail, it is revealed that the thrust to
the ground resulting from the difference between the excavation direction and shieldmachine position is considerably large. Therefore, the cross section pressure equals tothe differential pressure between the backfill grouting pressure and the groundpressure around tunnel, the thrust to the ground resulting from the difference
between the excavation direction and shield machine position, and the self-weight ofthe second half of shield machine without buoyancy force.
3.2.4

Load model at the tail passing

Because the backfill grouting pressure is smaller than the overburden pressure inthese monitoring results, the settlement occurred again after the tail passed till thecutter face passed. It is proved that the backfill grouting pressure is controlled to theinitial balanced condition with ground pressure around tunnel adequately. Therefore,
the cross section pressure equals to the differential pressure between the backfill
grouting pressure and the ground pressure around tunnel

195

Takahiro Konda, Junichi Nagaya, Tadashi Hashimoto, Hossain M. Shahin and Teruo Nakai

Step

1
step

2
step

Calculating formula
Load model(arrival of cutter face)Δp1=(pch-ph)*α (α=0,15)
Δp1=(pch-ph)*α
地山側圧
pch: cutter face pressure (center)
ph: lateral pressure
ph
p切羽圧
ch
α: influence ratio balance between the
cutter face pressure and the lateralpressure(α=0,15)(first half of shield machine)Δp2=pG+(ps-pi)*β1
pG: self-weight of the first half of shield
― ―
＝ β＝
×β
＝
machine without buoyancy force＋）（
ps: slurry pressureppp
pi: lateral pressure after 1step
β1:corrected value from 3D to 2D(β1=0,75)(second half of shield machine)Δp3=pG+(ps-pi’)*β2+pp×ββ ＋
pG: self-weight of the first half of shield＋）（（machine without buoyancy forceppp’
ps: back fill grouting pressurepi’: lateral pressure after 2step
×β ＋
pp: pressing load based on（
the excavation
×β ＋
＋
）
（
＋
）
）
（
direction and shield machine positionpβ2:corrected value from 3D to 2D(β1=0,25)(tail passing)Δp4=(ps-pi’)*β3
＝β
――
＝×β
ps:back fill grouting pressure）（pi’:lateral pressure after 3steppP’
β3:correction factor from 3D to 2D(β3=0,5)11

地山に作用する泥水・泥土圧
地山に作用する泥水圧
地山に作用する泥水圧
浮力を考慮した自重Gs(泥水・泥土の比重を考慮した分布圧)(泥水の比重分を考慮した分布圧)(泥水の比重分を考慮した分布圧)（マシン前半部の自重分）

地山応力

地山応力
地山応力
i
（異方応力状態）(異方応力状態)(異方応力状態)

――

3
step

――

浮力を考慮した自重（マシン後半部の自重分）

4
step

裏込注入圧+付加圧力
裏込注入圧+付加圧力

裏込注入圧

浮力を考慮した自重G（マシン後半部の自重分）

裏込注入圧+付加圧力
裏込注入圧+付加圧力

＝＝

×β
×β

2

――

裏込注入圧+付加圧力
裏込注入圧+付加圧力
浮力を考慮した自重
裏込注入圧
地山応力
地山応力
(裏込注入圧+付加圧力)と地山応力との差圧(裏込注入圧+付加圧力)と地山応力との差圧
地山応力（マシン後半部の自重分） マシン姿勢による荷重s（異方応力状態）(押上げ或は押下げ)

22

Figure 2:

地山応力
地山応力
地山応力

2

×β
×β

）

(裏込注入圧+付加圧力)と地山応力との差圧(裏込注入圧+付加圧力)と地山応力との差圧
マシン姿勢による荷重（異方応力状態）(押上げ或は押下げ)×β×β(裏込注入圧+付加圧力)と地山応力との差圧(裏込注入圧+付加圧力)と地山応力との差圧

Illustration of calculation model for ground deformation due to shield excavation

Correction factor for transforming 2D condition to 3D condition

This load model considering the construction loads with three dimensional problems
is different in each excavation stage. Because the 3D ground deformation is replaced
to the 2D problem in this study, correction factors for transforming 2D condition to
3D condition are presumed based on the reference simulating results as Figure 2.

196）(押上げ或は押下げ)

＝＝

地山応力
地山応力
地山応力
i
（異方応力状態）×β
×β(裏込注入圧+付加圧力)と地山応力との差圧(裏込注入圧+付加圧力)と地山応力との差圧
マシン姿勢による荷重

33

裏込注入圧+付加圧力
裏込注入圧+付加圧力
s
裏込注入圧

3.2.5

＝＝

地山応力
地山応力
地山応力
i
（異方応力状態）

裏込注入圧
s

泥水圧と地山応力の差圧
泥水圧と地山応力の差圧

In situ Measurement and Numerical Analysis on Tunnel Lining and Ground Behaviour due to Shield Excavation

3.3

Outline of FE Analysis

Figure 3 shows the finite element mesh. The lateral boundary is extended to the 45degree influence line from the bottom of the first tunnel, and the lower boundary is
configured the twice of shield diameter from the bottom of the first tunnel taking into
account the dense sandy layer and stiff clayey layer under the first tunnel. The firsttunnel lining is installed immediately after the completion of the first shield exaction
and before the excavation of the second shield tunnel.
Soil parameters for elasto-plastic FE analysis are shown in Table 2. These parameters
are decided based on the reference [1], because the same elasto-plastic FE program
was employed for the braced excavation at the similar ground condition site. Also, theinitial stress in the ground is set to become a prescribed over consolidated ground by
self-weight consolidation and uniform loading/unloading simulation from the bottomof the ground. Since the excavation time of the shield tunnel is short, about half an
V1hour,
the elasto-plastic FE analysis is carried out considering undrained condition.
C1
0.

5.

10.

15.

20.

25.

30.

35.

40.

45.

50.

55.

60.

65.

70.

75.

80.

85.

90.

0 10 20 30 40 50 60▽O.P.+4.67m

B

X

3720

0.

Aus

沖積砂層(As)
Aus

15500

15500

-5.

0

-10.

-5

Amc1

下水φ3150

Amc(1)

2147

25000

沖積粘土層
(Ac)

-15.

洪積粘土層(Oc)

-20.

31000

Amg
Amc2

500

沖積砂層(As)

12

Ams
Oc2

-15

11

沖積粘土層
(Ac)

1000

▽O.P.-11.872m

Amc(2)

2000

Amg

後行(北行)
シールド

2000

沖積砂礫層
(Ag)

1000

-10

先行(南行)
シールド

Ams▽O.P.-17.307m
1000

洪積砂礫層(Tg)

Oc2

12150

-25.

-20

95. 100.

3つの計測器設置位置は南行
シールド側部から1.0m離れ

15
No. .67m.+4 m
O.P=50.23
Dep

O.P.+5.0m

Tg

Tg

-30.

-25
Os2

Os2(1)

計測器：層別沈下計：連通管式沈下計：多段式傾斜計：間隙水圧計-35.

：パッド式土圧計

YFigure 3:
Table 2:Y

Pleisto-cene

Finite element mesh
Soil parameters for elasto-plastic FE analysis

Deformatio
Poassonn
Ratio
ModulusX(GL-m) (times) γt (kN/m3) E (kN/m2)
ν
Aus
7.60
20
18
56000
0.30
Amc1
12.60
0
16
17745
0.45
Amg
16.10
40
19
112000
0.30
Amc2
20.75
4
17.5
31500.0
0.45
Ams
21.70
39
19
107800
0.30
Oc2
23.40
10
18
43750
0.45
Tg
31.00
90
20
252000
0.30
Os2-1
33.60
30
18
84000
0.30
Os2-2
38.70
90
20
252000
0.30

Layer
Z

Holo
-cene

Os2(2)

：ひずみ計

Lower
Depth

SPT
N-value

Unit
WeightSoil Parameters for Elasto-plastic FE Analysis (FEM tij-2D)
λ
0.07
0.16
0.07
0.25
0.07
0.10
0.035

κ
0.01
0.02
0.01
0.04
0.01
0.02
0.0023

N
0.68
1.23
0.68
1.50
0.68
1.85
1.10

β
1.50
1.57
1.50
1.70
1.50
1.70
2.00

aAF

aIC

3.50
2.25
3.50
3.55
3.50
4.00
3.20

200
40
200
130
200
3500
30

100000500
100000500
100000
500
500

0.007

0.0005

1.10

3.20

2.00

30

500

Rcs

197

Takahiro Konda, Junichi Nagaya, Tadashi Hashimoto, Hossain M. Shahin and Teruo Nakai

4

RESULTS AND DISCUSSION

Figure 4 shows the comparison between observed data and calculation results forvertical displacement above the first tunnel and horizontal displacement at a
distance of 1m from the first tunnel in each excavation steps. In these figures, FE
calculation results with elasto-plastic model and elastic model are illustrated.
At the arrival of cutter face, settlement above the first shield tunnel and expandedhorizontal deformation are to some extent in the observed data. On the other hand, theground movement around first tunnel is insignificant in FE calculation results as thecutter face pressure is balanced with the lateral pressure. This tendency is confirmedin both elasto-plastic and elastic calculation results.
At the first half of shield machine, 4,7mm settlement above tunnel and about 3mm
expanding horizontal deformation occur in monitoring data. In elasto-plastic
calculation results, about 10mm settlement above tunnel and about 3mm expanding
horizontal deformation at spring line of first tunnel are seen. Because the cutter facepressure is smaller than the lateral pressure above the first tunnel, this loading modeltends to the stress released condition. Therefore observation and calculation have agood correspondence with this settlement tendency qualitatively. Since the Amc2
layer in FE analysis, which is deposited above the first tunnel, is considered softer
than the actual ground condition, calculation settlement is twice of the observational
settlement. As a result, the horizontal ground at the right shoulder part of first tunnel
mobilizes inside tunnel, and it shows different tendency with the observed data. The
settlement trough above the first tunnel of the elasto-plastic calculation indicates local
settlement. On the other hand, in the elastic calculation the settlement trough is rather
gentle in shape, in short, both settlement troughs show different tendency.
At the second half of shield machine, due to the influence of the thrust to theground, about 7mm heave and maximum 5mm expanding horizontal deformation
occurred in the monitoring ground. The elasto-plastic analysis shows about 4mm
heave and maximum 5mm expanding horizontal deformation at the spring line
position of the first tunnel corresponding position of the shield machine in thefield. The magnitude of the settlement above the shield tunnel is different between
the observation and elasto-plastic calculation. But the increment of the settlement
between the first half and second half of shield machine in the elasto-plastic FE
analysis has quantitatively very good agreement to that of the observed data.

198

In situ Measurement and Numerical Analysis on Tunnel Lining and Ground Behaviour due to Shield Excavation

3つの計測器設置位置は南行
シールド側部から1.0m離れ

5No.1 .67m+4
O.P.50.23m
Dep=

O.P.+5.0m

3720

5▽O.P.+4.67m

0 10 20 30 40 50 60B5沖積砂層(As)
Aus
0

0

-5

-5
Amc(1)

15500

15500

0

-5

下水φ3150

2147

25000

沖積粘土層
(Ac)

-10

沖積砂礫層
(Ag)

2000

1000

▽O.P.-11.872m

沖積粘土層
(Ac)

Ams

沖積砂層(As)

Oc2

洪積粘土層(Oc)

500

Amc(2)

2

-15

2nd

先行(南行)
シールド

1
11

-15

-15

-10

31000

後行(北行)
シールド

1000

Amg

2000

-10

2nd

▽O.P.-17.307m
1000

洪積砂礫層(Tg)

-20

12150

-20

-20

Tg

1st

1st

-25

-25

-25
Os2

計測器

horizontal deformation：層別沈下計(obserbation)：連通管式沈下計：多段式傾斜計：間隙水圧計
vertical deformation：パッド式土圧計(observation)：ひずみ計
calculation (elasto-plastic model)
calculation (elastic model)

-30

-35
-15

5
No.1 .67m+4
O.P.50.23m
Dep=

O.P.+5.0m

-10

-5

0

3つの計測器設置位置は南行
シールド側部から1.0m離れ

5mm

-30

5mm

5

10

15

3720

5

-10

-5

0

5mm
5mm

5

10

15

5

▽O.P.+4.67m

0 10 20 30 40 50 60

B

-35
-15

horizontal deformation(obserbation)
vertical deformation(observation)
calculation (elasto-plastic model)
calculation (elastic model)

沖積砂層(As)
Aus

0
15500

-5

-5
Amc(1)

15500

0

0

-5

下水φ3150

2147

25000

沖積粘土層
(Ac)

洪積粘土層(Oc)-152

沖積砂層(As)

Oc2

1
11

沖積粘土層
(Ac)

Ams

2000

1000

▽O.P.-11.872m

Amc(2)
-15

-10

31000

後行(北行)
シールド

1000

沖積砂礫層
(Ag)

500

Amg

2000

-10

-10

-15

先行(南行)
シールド▽O.P.-17.307m
1000

洪積砂礫層(Tg)

2nd

-20

12150

-20

-20

2nd

1st

1st

Tg

-25

-25

-25
Os2

-30

-35
-15

Figure 4:

計測器
horizontal deformation：層別沈下計(obserbation)：連通管式沈下計：多段式傾斜計
vertical deformation：間隙水圧計：パッド式土圧計(observation)：ひずみ計
calculation (elasto-plastic model)
calculation (elastic model)

-10

-5

0

5mm

-30

5mm

5

10

15

-35
-15

horizontal deformation(obserbation)
vertical deformation(observation)
calculation (elasto-plastic model)
calculation (elastic model)

-10

-5

0

5mm
5mm

5

10

15

Comparison of vertical and horizontal ground deformation between observed data andcalculation results for each calculation step199

Takahiro Konda, Junichi Nagaya, Tadashi Hashimoto, Hossain M. Shahin and Teruo Nakai

This same tendency is also captured in the distribution of lateral displacement at 1m
distance from the tunnel. On the other hand, the elastic calculation results can explain
the tendency of the heave above the tunnel and the expanding phenomenon for
considering the thrust model based on the shield machine position. However, forinstance, the influence of heave extends to the far ground surface, the elastic
calculation results are obviously different in comparison to the monitoring results andthe elasto-plastic calculation results. Moreover, the heave above the tunnel
significantly larger compare to the expanding horizontal deformation, this tendency
differs vastly from the observation and the elasto-plastic calculation.
The deformation behaviour at the tail passing is similar to its behaviour at the second
half of shield machine. Nevertheless, as the backfill grouting pressure balances withthe lateral pressure, the local heave is restricted appropriately and elasto-plastic
calculation results have a good correspond with monitoring data in comparison withelastic calculation results.
Figure 5 shows the distribution of the first tunnel lining pressure increment and stressdevelopment due to the second shield excavation based on the comparison between
observation and elasto-plastic calculation.
At the close part of the first tunnel lining to the second shield excavation, the thrust
and the cross section force fluctuate. But there is little change at the opposite part. The
elasto-plastic FE analysis perfectly capture the influence of the construction load thesame way as observed in the monitoring data. The elasto-plastic FE analysis is able toexplain these actual behaviours adequately that cannot be expressed by the analysis
using the conventional stress release ratio.
5

CONCLUSIONSIn this research, some results can be concluded as follows;
1) The shield excavation is divided four construction process arrival of the cutter
face, the first half of shield machine, the second half of shield machine, andthe tail passing. The ground movement around shield tunnel are different ineach construction steps. Owing to predict the ground deformation behaviour
due to shield excavation appropriately with numerical analysis, it is necessary
to take into account of the construction load in each construction stage.

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In situ Measurement and Numerical Analysis on Tunnel Lining and Ground Behaviour due to Shield Excavation

Lining Pressure

Bending Moment

-50

50
0

0

50
100

-50
Unit : kN/m

2

second half of shield machine (observation)
tail passing (observation)
second half of shield machine (calculation)
tail passing (calculation)

Figure 5:-100

Unit : kNm＋ : in tension, out compression－ : in compression, out tension

Comparison of distribution of earth pressure increment and cross section force of 1st
tunnel lining between observed data and calculation results for each calculation step2) It can be thought that some factors for ground deformation are - i) the balance
between the cutter face pressure and the lateral pressure at the cutter face, ii) thebalance between the cutter face pressure and the lateral pressure at the first half ofshield machine, iii) the differential pressure between the backfill grouting pressure
and the ground pressure around tunnel at the second half of shield machine and at
the tail passing, and iv) the self-weight of shield machine. Sometime, the thrust
associated with the difference between the excavation direction and shieldmachine positions has an impact to ground deformation.
3) The FE analysis with elasto-plastic constitutive model of soil and the load model
considering construction loads is employed to simulate the ground deformation
behaviour around tunnel and the nearby tunnel lining pressure and stressdevelopment. It is revealed that the elasto-plastic FE analysis is able to explain
actual behaviours adequately that cannot be expressed by the analysis using theconventional stress release ratio. Moreover, the elasto-plastic calculation results
have a good agreement with the monitoring data in comparison with the elastic
calculation results.

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Takahiro Konda, Junichi Nagaya, Tadashi Hashimoto, Hossain M. Shahin and Teruo Nakai

REFERENCES[1] Konda T., Shahin, H. M. and Nakai, T.: Numerical Analysis for backside
ground deformation behaviour due to braced excavation, 9th World
Congress on Computational Mechanics and 4th Asia Pacific Congress on
Computational Mechanics, P Antolin et al IOP Conf. Ser.: Mater. Sci. Eng.
Vol.10, No.1, 2010.
[2] Nakai, T., Hinokio, M. 2004. A Simple Elastoplastic Model for normally andover consolidated soil with unified material parameters. Soils andFoundations, 44(2), pp. 53-70.
[3] Shahin, H. M., Nakai, T, Zhang, F., Kikumoto, M. and Nakahara E.,“Behavior of ground and response of existing foundation due to tunneling”,
Soils and Foundations, Vol. 51, No. 3, 2011, pp. 395-409.
[4] Oota H., A. Hashimoto, J. Nagaya and S. Kan: Measurement andconsideration of ground deformation due to shield tunnel construction loads,
The Proc. Of Tunnel engineering JSCE, vol.16, pp.395-402, 2006.

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