Slurry shield TBM

Course in Tunnelling and Tunnel Boring Machine
Kurs w zakresie drążenia tuneli oraz maszyny drążącej
OVERVIEW ON TUNNEL BORING MACHINES
Prof. Eng. Sebastiano PELIZZA
1

Full face mechanized tunnelling
(continuous ground excavation and spoil extraction)
Continuous spoil
removal
The free span coincides with the last
stretch of the tunnel where the rock is
being excavated and the supports cannot
be installed yet (very variable length,
depending on the TBM type: open,
shielded, with or without face
counterpressure).
The advance is performed in two steps:
- Active stroke of the cutting head for the
excavation (and the spoil extraction)
usually1,4 ÷ 1,8 (2,0) m;
- Advance of the whole machine when the
cutting head has been stopped.
2

TBM TUNNELLING
Full face mechanized excavation, using TBM for the excavation of tunnels in rock.
The main commitment of the TBM is to break the rock.
Example of an EPB machine: 1. Cutting wheel, 2. Drive unit, 3. Push cylinder, 4. Air lock, 5. Screw conveyor, 6.
Erector, 7. Screw conveyor gate, 8. Segment handler, 9. Segment crane, 10. Belt conveyor.
Full face mechanized excavation method, using mechanized shields and with
pressure at the face for the excavation of tunnels in soil.
The main problem done by the instability of the ground so the main
commitment of the TBM is to create a stable working site at the face.
3

Full face mechanized excavation, using TBM for the excavation of tunnels in rock.
The main commitment of the TBM is to break the rock.
6

Hard rock TBM
7

Hard rock TBM
10

Rock tools
14

copy-cutter
cutter
15

Tunnel reaming machine
19

Tunnel reaming machine
20

Shielded TBM advancing
21

Open - face shield TBM
22

Open - face shield TBM
23

Double shield
24

Double shield
25

Instant lining
29

Segmental lining – cross section
31

Produzioni medie ottenute con frese a doppio scudo telescopico anche
considerando i fermi per eventi geologici straordinari
Grandori,
331998

Example of an EPB machine: 1. Cutting wheel, 2. Drive unit, 3. Push cylinder, 4. Air lock, 5. Screw conveyor, 6.
Erector, 7. Screw conveyor gate, 8. Segment handler, 9. Segment crane, 10. Belt conveyor.
Full face mechanized excavation method, using mechanized shields and with
pressure at the face for the excavation of tunnels in soil.
The main problem done by the instability of the ground so the main
commitment of the TBM is to create a stable working site at the face.
36

The ground moves phisically towards the tunnel
38

Bacino di subsidenza
S
x
−
2i
( x)
= wmax
⋅e
Settlements of the surface
with a shallow tunnel in
loose ground
2
2
40

RISK MANAGEMENT
• Typical patterns of ground failure in urban area
41

Shielded TBM advancing
43

MACHINES PROVIDING IMMEDIATE FRONTAL AND
PERISPHERAL SUPPORT
44

Possible failure
mechanism
Compressed air
compressed air
Slurry Shield
slurry
Horn (1961)
EPB
excavated soil
45

Compressed air support
46

Slurry face support
47

Earth – pressure balance support
48

Soil tools
49

Soil tools
50

Mechanical – support TBM
51

Mechanical – support TBM
52

Compressed - air TBM
53

Boom – type compressed – air TBM
54

Slurry shield TBM
55

Slurry shield TBM
chamber
56

Hamburg, Germany - 4th River Elbe Tunnel.
Diameter: 14,200mm
Cutterhead power: 3,400kW
Tunnel length: 2,560m
Geology: Glacial drift, silt and
gravel, sand, boulders
Contractor: Bilfinger Berger AG
Dyckerhoff &
Widman AG
Heitkamp GmbH
HOCHTIEF AG
Philipp Holzmann AG
Wayss & Freytag AG
Ed. Züblin AG
57

Slurry shield TBM
1 3
1. Submerged wall
2. Working chamber
4
3. Compressed air
2
4. Pressure bulkhead
58

Fine grained soil
Coarse grained soil
filter cake (d 10 < 0,2 mm).
sandy gravel. stagnation of slurry
60

k=10 [m/s]
Slurry-Shield
Permeability „k“
k=10 -3 [m/s]
k=10 -7 [m/s]
EPB-Shield
k=10 -12 [m/s]
61

Conceptual scheme of an EPBS with principal components intervening during the
excavation.
66

EPB with muck control.
1. Excavation
chamber.
2. Screw conveyor.
3. Muck hopper.
4. Single-piston
pumps.
5. Gate valve.
69

Main bearing: inspection and service
71

Screw conveyor: service
72

Earth Pressure Balance machine
74

EPB-Giant for Barcelona Metro Line 9.
Diameter: 12,060mm
Cutterhead power: 4,000kW
Tunnel length: 8,500m
Geology: Granodiorite, sand,
clay, gravel,
boulders
Contractor: Dragados
Necso
ACS
Comsa
Sorigue
78

Mega-Tunnel in Madrid, Spain.
79

Herrenknecht TBM S-300, M-30 Madrid, Spain.
Diameter: 15,200mm
Cutterhead Power: 12,000kW + 2,000kW
Maximum Torque: 125,268kNm
Tunnel Length: 3,650m
Geology: Peñuela,
peñuela + gypsum,
massive gypsum
Contractor: Necso
Ferrovial - Agroman S. A.
80

S-300, M-30 Madrid, Spain.
81

k=10 [m/s]
Slurry-Shield
Permeability „k“
k=10 -3 [m/s]
k=10 -7 [m/s]
EPB-Shield
k=10 -12 [m/s]
86

TBM face stability control
EPB machine example of applications
100
clay silt sand gravel
90
Percentage finer by weigth [%]
80
70
60
50
40
30
20
10
0
0,001 0,01 0,1 1 10 100
grain size [mm]
Aviles (2002) Milano (1) (1996) Milano (2) (1996) Valencia Nivel 3 e 6 (1) (1996)
Valencia Nivel 3 e 6 (2) (1996) Valencia Nivel 4 (1) (1996) Valencia Nivel 4 (2) (1996) Valencia Nivel 5 (1) (1996)
Valencia Nivel 5 (2) (1996) Izmir (1) (1993) Izmir (2) (1993) Izmir (3) (1993)
Essen (1) (1993) Essen (2) (1993) Milano (1) (1998) Milano (2) (1998)
Taipei (1) (1993) Taipei (2) (1993) Avila (2002) Sevilla (1)
Sevilla (2) Barcellona (1) Barcellona (2)
89

CUTTING WEELS
The ratio between the opening area in the cutterhead and the excavated section has a direct
influence on the mechanical-support capacity of the excavation face and on the face-support
pressure control.
Usually, for the SS or hydroshield, the cutterhead opening ratio is even more than 50% while
for an EPBS it varies between 20 and 35%.
In fact, the formation of cake in a Hydroshield needs a very intimate contact between the
face and the slurry.
On the contrary, the support effect of the EPB principle is based on the “mechanical”
contrast of the muck, which has been accumulated inside the “plenum”. This implies that the
structure of a cutterhead for SS should be lighter than the structure of the one for EPBS: the
greater the opening ratio, the smaller the number of cutter tools which can be installed.
90

The capability for the cutterhead to excavate through boulders has been progressively
improved, with the aim of avoiding the entry of the workers into the working chamber for
manually removing the pieces that are too large to be removed by the machine (BTS, 2005).
However, the situation is that in the presence of many boulders, whose dimensions are close
to the maximum allowable for a certain machine, it is possible to install a “stone crusher” in
an SS, but not in an EPBS.
However, on the EPB cutterhed, which is stronger, it is possible to install disk cutters able to
break the hard rock boulders.
Thank to these reason, the working field of EPB is extending to the larger grain size
distributions as well as to fractured or karstik rocks where it is necessary to stop the ground
water.
91

CUTTING WHEELS - SLURRY SHIELD
Usually, for the SS or hydroshield, the cutterhead opening ratio is even more than 50% while for an EPBS it
varies between 20 and 35%.
In fact, the formation of cake in a Hydroshield needs a very intimate contact between the face and the slurry.\
92

CUTTING WHEELS - EPB SHIELD
On the contrary, the support effect of the EPB principle is based on the “mechanical” contrast of the muck,
which has been accumulated inside the “plenum”. This implies that the structure of a cutterhead for SS
should be lighter than the structure of the one for EPBS: the greater the opening ratio, the smaller the
number of cutter tools which can be installed.
93

ROCK TBM
94

SLURRY SHIELD
95

SLURRY SHIELD
96

EPB SHIELD
97

EPB SHIELD
98

EPB SHIELD
99

EPB SHIELD
100

EPB SHIELD
Diameter: 6270 mm
Total Length: 97 m
Total Weight: 615 tons
Installed Power: 2000 kW
101

EPB SHIELD
102

EPB SHIELD
103

EPB SHIELD
104

EPB SHIELD
105

106

In emergency situations, for example a collapse of the face, the
behaviour of the two types of machines is completely different:
in the case of an EPBS, collapsing ground cannot enter the plenum,
which is already full of solid material. If the process is under control, the
TBM operator can easily close everything and ask for the intervention of
the tunnel manager in order to take the foreseen countermeasures, foe
example ground treatment all around the critical zone, which, if
successful, could avoid serious consequences on the surface.
The most important thing is that, once the choice is made, a skilled TBM
driving crew supported by an experienced, control team should
implement a robust and integrated control system to complement the
excavation process.
107

108

Grandori, 1998
109

110

111

Machine not providing
immediate support
Machine providing immediate perispheral support
112