1737
Technical Committee 204 /
Comité technique 204
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
Existing
box-module
Excavating elements
Ground
Joint elements (A)
Joint elements (B)
Advancing box-module
Tunnel boring machine
Figure 5. Arrangement of joint elements.
3 FINITE ELEMENT SIMULATION OF THE MODULAR
APPROACHED TUNNELLING WORK
A three dimensional finite element analyses were conducted to
simulate the construction process of the wall structure of a
modular approached tunnelling work in Japan. The sixty
rectangular box-modules of 0.85 m width, 0.85 m height and
30.0 m long were inserted in order to build the lining frame.
These box-modules were integrated finally to the lining frame
in approximately 23.10 m width and of 8.14 m height with earth
coverage of only 1.20 m underneath major rail tracks as shown
in Figure 4. The site stratigraphy determined from borehole logs
is also shown in Figure 4.
In this study, for convenience, the isotropic elastic model was
used to model the stress-strain behaviour of the soil, the tunnel
boring machine and the box-modules. Most of the input
parameters were determined from the results provided by
standard geotechnical tests on samples obtained at various
depths. Other input parameters, which were not able to be
determined from these tests, were assessed by the results of the
in-situ geotechnical tests. Summary descriptions of the soil
divisions and input parameters based on the examination of site
samples were given below:
(1) Bank-soil : E=5600 kN/m
2
, ν=0.333, ρ=1.735 g/cm
3
(2) Fine sand : E=5600 kN/m
2
, ν=0.333, ρ=1.786 g/cm
3
(3) Silt : E=1000 kN/m
2
, ν=0.444, ρ=1.531 g/cm
3
(4) TBM and advancing box-module : E=4.7×10
5
kN/m
2
,
ν=0.300,
ρ
=1.786 g/cm
3
(5) Existing box-module (lining frame): E=4.7×10
7
kN/m
2
,
ν=0.290, ρ=2.300 g/cm
3
(6) Excavating elements : E=300kN/m
2
, ν=0.100, ρ=2.300
g/cm
3
where E is Young's modulus, ν is Poisson's ratio and ρ is bulk
density.
Since the box-module was filled with mortar after completion
of advancement, the properties were different between the
existing box-modules (lining frame) and the advancing box-
Figure 6. Three dimensional finite element model.
module. For the excavating elements, a Young’s modulus of
300kN/m2, Poisson's ratio of 0.1 and the thickness of 1 m were
selected.
Goodman type joint elements (Goodman R.E., et.al, 1968)
were placed at the interface (A) between the soil and the box-
module and (B) between the existing box-module and the
advancing box-module, in order to investigate inter-face
frictional effects on ground deformation as shown in Figure 5.
The frictional resistance stiffness of the joint elements (A) and
(B) are 100 and 200kN/m respectively and the normal stiffness
of the (A) and (B) are 5.0×105 and 1.0×106 kN/m respectively.
The measured pull jacking forces were applied as nodal forces
in front of the tunnel boring machine.
Figure 6 shows three dimensional finite element model using
the analyses. Figure 7 shows the order of the box-module
construction. The box-modules (B, C, D, E) at the top part of
the lining frame were first constructed, and then the box-
modules (F, G, H, I, J, K and M1, N1, O1) at the vertical wall of
the lining frame were constructed, after which the box-modules
(L, M, N, O) at the invert were constructed. The order of the
advancing of box-module in the invert section was [N2 and L1]
→
N3
→
[M2 and L2]
→
[M3 and N4]
→
[M4 and N5]
→
M5
→
[M6 and N6]
→
M7
→
O2. Braces [ ] indicates that two
box-modules were advanced simultaneously.
During constructing the box-modules of the invert part of the
lining frame, the contractor measured vertical displacements of
the existing top part of the lining frame at (already integrated)
B10, B5, A, C5 and C9 (see Figure 8) until the box-modules M6
and N6 were completely advanced.
Figure 9 and Figure 10 show the measured and the calculated
vertical settlement trough on the top part of the existing lining
frame at the end of the tunnel during the advancement of the
invert box-modules (L, M, N, O) respectively. The measured
and computed vertical displacement at the end of the box-
module A is plotted against the order of the box-module
constructions in Figure 11. Although the calculated value
demonstrated an increase in vertical displacement during initial
Figure 7. The order of the construction processes of box-module.
