Civil works executed on MetroTorino Line 1 extension (unmanned subway)

1. TORINO UNMANNED SUBWAY
CIVIL WORKS
Ing. Giorgio Fantauzzi
Project Leader
Turin, 12 July 2010

2. TORINO SUBWAY LINE 1 : GENERAL DESCRIPTION
GTT is the concessionary for design, construction
and management of the Metro Line 1, one of the
main infrastructures in the public transportation
plan for the Torino area.
The civil works design was governed by the VAL
(Automated Light Vehicle) system characteristics.
The train is 2.08 m wide, 52 m long and its
maximum passenger capacity is 440 people (6
pass./m2).
Base on width of train, a single 6.8 metre diameter
circular tunnel contains the double track line has
been chosen.
The tunnel was bored by TBM.

3. TORINO SUBWAY LINE 1 : CIVIL WORKS
Tunnel 3.000 m tunnel bored using a TBM EPB (earth pressure balanced
shield machines)
Stations 6 stations cut & cover with diaphragms. First station (Marconi) was
TBM job site and the last (Lingotto) with train interchange
Shafts 5 aeration shaft, built using micropiles
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4. TORINO SUBWAY LINE 1 : GEOLOGY / GEOTECHNICS
The formation interested from the tunnel line is mainly constituted by fluvio-glacial and fluvio-Rissian deposit (Quaternary), of gravel
sand and cobbles in silty matrix. Within this formation there are 4 units identified by specific granulometric characteristics and
different cementation:
• unit 1 – superficial ground
• unit 2 – gravel with sand from loose to slightly cemented
• unit 3 – gravel with sand from weak to medium cemented
• unit 4 - gravel with sand from medium to highly cemented.
The tunnel excavation interested mainly unit 2 and 3. The ground water level varied from tunnel invert up to a maximum height of 7
m measured at crown (Shaft n°6).

5. TORINO SUBWAY LINE 1
MAJOR PROBLEMS:
• Interferences with utilities and facilities;
• Presence of peoples opposed to the project;
• Interferences with existing structures;
• Surveys to remove archaeological and weapons
from 2nd War;
• Traffic management near work sites,
interferences with commercial activities;
• Public opinion;
• High groundwater level.
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6. TORINO SUBWAY LINE 1 : FIRST OPERATIONS
Job site alteration
Facility relocation
Diaphragms execution
Station box execution
Site cleaning and preparing for TBM
TBM assembly

7. TORINO SUBWAY LINE 1
Work site
Transportations
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8. TORINO SUBWAY LINE 1
Utility relocation
Tecnological wires:
- Electric
- Telephonic
- Gas pipe
- Acqueducts
- Sewer
- Parking
- Monuments
- Other
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9. TORINO SUBWAY LINE 1 : STATION GEOMETRY
• Station dimensions 55x20m;
• Station deep from 20 to 25m;
• Two entrances and one lift for each station;
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10. TORINO SUBWAY LINE 1 – THE EPB MACHINE
Mechanized excavation : Basic principles
The Earth Pressure Balanced (EPB) tunnelling method owns it’s name
from the way the front face of the TBM is supported during excavation,
using earth pressure. The principles of the EPB-tunnelling method can
described as follows (Kanayasu, Yamamoto and Kitahara, 1995):
• The soil is excavated by rotating cutter heads;
• The excavated soil is mechanically agitated and fills the face and an
excavation chamber.;
• Using the thrust of the shield machine, by means of hydraulic jacks,
the excavated soil is pressurized to stabilize the excavation front (force
equilibrium);
• Control of the soil pressure in the chamber is done by adjusting the
amount of soil discharged through the screw conveyor or other soil
removal devices and the amount of soil excavated to counterbalance
earth and groundwater pressure (volume equilibrium);
• The excavated soil in the chamber and the screw conveyors work as
a water seal.
The earth pressure support method is generally used in cohesive soils,
enabling it to be used as a supporting medium itself, with the use of
conditioning materials if necessary.
A

11. TORINO SUBWAY LINE 1 – THE RING
The tunnels have inner diameter of 6.8mt and is lined with pre-cast 30 cm thick segments in reinforced concrete,
connected by EPDM gaskets to insure water tight conditions. Even withrather small curves and consequent assembly
offsets of the segment ring, there is no water passage within the tunnel.
Each 1.4 m long ring consists of 5 “normal” elements plus one “key” element that enables the closure of the ring, a
“universal” lock that permits to adapt the ring to any kind of radius, from the minimum to the linear one, by a simple
rotation of every ring compared to the previous one along the tunnel axis at a given angle.
The injection of mortar behind the segments, performed immediately at the beginning of the excavation procedures,
ensures the reduction of superficial collapse and the correct confinement/bedding of the lining.

12. TORINO SUBWAY LINE 1 – THE CUT AND COVER
METHOD
CONSTRUCTION PHASES
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13. TORINO SUBWAY LINE 1
MANAGEMENT OF THE GREEN ELEMENTS
The ante-operam activities are:
• Census of all the trees which could interfere with the works;
• Evaluation, for each tree, of the interference percentage;
• Evaluation of the possibility of maintaining the trees
(properly protected by crashes) in the area;
• Evaluation of the necessity of removing the trees;
• Definition of the removal intervention typology (cutting
down or transplanting) in accordance with:
species
dimension
phytopathological status
• Evaluation of the possibility of relocating the trees in original
site, at the end of the works.

14. TORINO SUBWAY LINE 1
MANAGEMENT OF THE GREEN ELEMENTS
The transplanting has been realized by special equipments in order
to safeguard the trees radical planting and guarantee a correct
rooting in the new site.

15. TORINO SUBWAY LINE 1
UTILITY RELOCATION

16. TORINO SUBWAY LINE 1
UTILITY RELOCATION

17. TORINO SUBWAY LINE 1
UTILITY RELOCATION

18. TORINO SUBWAY LINE 1
SITE CLEANING

19. TORINO SUBWAY LINE 1
SITE CLEANING

20. TORINO SUBWAY LINE 1
EXECUTION OF GUIDE WALLS

21. TORINO SUBWAY LINE 1
EXECUTION OF GUIDE WALLS

22. TORINO SUBWAY LINE 1
EXCAVATION OF DIAPHRAGMS

23. TORINO SUBWAY LINE 1
EXCAVATION OF DIAPHRAGMS

24. TORINO SUBWAY LINE 1
REINFORCEMENT

25. TORINO SUBWAY LINE 1
POURING OF CONCRETE

26. TORINO SUBWAY LINE 1
POURING OF CONCRETE

27. TORINO SUBWAY LINE 1
DEMOLITION OF TOP HEAD OF
DIAPHRAGMS

28. TORINO SUBWAY LINE 1
TOP SLAB REINFORCEMENT

29. TORINO SUBWAY LINE 1
WATERPROOFING

30. TORINO SUBWAY LINE 1
EXCAVATION OF STATION

31. TORINO SUBWAY LINE 1
EXCAVATION OF STATION - USE OF STRUTS
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32. TORINO SUBWAY LINE 1
BOTTOM SLAB REINFORCEMENT

33. TORINO SUBWAY LINE 1
TBM SUPPORTING SADDLE

34. TORINO SUBWAY LINE 1
DIAPRHAGM DEMOLITION FOR TBM
START

35. TORINO SUBWAY LINE 1
TBM ASSEMBLY

36. TORINO SUBWAY LINE 1
TBM ASSEMBLY

37. TORINO SUBWAY LINE 1
WORK SITE FINAL LAYOUT
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38. TORINO SUBWAY LINE 1
PUSH PORTAL FOR START OF TBM

39. TORINO SUBWAY LINE 1
EPB START – USE OF STEEL
SEGMENT IN STATIONS

40. TORINO SUBWAY LINE 1
TUNNEL UNDER CONSTRUCTION
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41. TORINO SUBWAY LINE 1
ARRIVE AT NIZZA STATION

42. TORINO SUBWAY LINE 1 – SHAFT CONSTRUCTION

43. TORINO SUBWAY LINE 1 – SHAFT CONSTRUCTION

44. TORINO SUBWAY LINE 1 – SOIL IMPROVEMENT
To avoid water inflow
Break In TBM
Break Out TBM
Bottom grouting
To reduce settlements
Lateral shield Full improvement at crown
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45. TORINO SUBWAY LINE 1 – SOIL IMPROVEMENT
Soil improvement solutions have been implemented where the
assessments indicate potential risk of damage to the pre-existing
structures. Such interventions include improving the properties of the
ground and mitigating the deforming effects induced by tunnelling by
means of low-pressure cement injection grouting. A consolidated slab
is created above the tunnel section in order to avoid any localized
instability from developing around it.
Different grouting geometry have been defined, based on relative
position between the tunnel and pre-existing structures, as well as
site accessibility and surface site areas use.
The project includes full-face cement grouting in the areas adjacent
to the stations where the TBM will enter into or exit from the stations:
the diaphragm walls in these particular areas will be partially
demolished to let the TBMs in and out. In accordance with the
environmental conditions, the drilling and grouting operations were
done from the surface and/or from in service shafts and tunnels.

46. TORINO SUBWAY LINE 1 – ENVIRONEMENTAL
MONITORING
NOISE
The noise monitoring campaigns are carried out on 20 receptors with:
• 39 measurements semi-fixed workstations;
• 41 measurements fixed workstations;
• 15 short period measurements, living environment.
VIBRATION
The vibration monitoring campaigns are in
progress and realized on 14 receptors:
• 37 short period measurements
• 10 long period measurements (24 hours)
AIR
In the following chart have been highlighted
the reference and results with the trends
and the PM10 limits exceeding.
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47. TORINO SUBWAY LINE 1 – STRUCTURAL MONITORING
To reduce the residual risk we defined trigger levels for displacement/rotations on
structures and surrouding buildings
TRIGGER LEVELS
• Attention: increase the frequency
of monitoring data to understand
the real behaviour
•Alarm: apply counter-measures to
solve the problems
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48. TORINO SUBWAY LINE 1 – STRUCTURAL MONITORING
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49. TORINO SUBWAY LINE 1 – STRUCTURAL MONITORING
Automatic monitoring with
electrolevels : the distortions
measured during the excavation
phase was less than the
established trigger levels
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50. TORINO SUBWAY LINE 1 – CONCLUSION OF WORK
START: 08.01.2007
Finishing date (CONTRACTUAL) : 03.05.2010
Finishing date (REAL) : 03.02.2010
TECNIMONT finished the civil works
two months before the foreseen
contractual date
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info@mairetecnimont.it – www.mairetecnimont.it