Metro Torino Extension - Design and construction problems

Construction of the Turin Metro
Line 1 Extension Marconi-Lingotto
Copenhagen, 18 June 2013
Giorgio Fantauzzi
Project Leader Tecnimont (Maire Tecnimont Group)
Danish Society for Tunnel
and Underground Works

Infratrasporti.To S.r.l. is a company owned
exclusively by the City of Turin.The purpose
of the company is:
 to own and manage existing
infrastructure
 to plan and construct new infrastructure,
including railways for passenger and
freight transportation (both public and
private)
Infratrasporti.To S.r.l. owns Line 1 of the
Turin Automatic Underground (13.2 km) and
the N. 4 Tramway line (18 km).
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 meters
diameter circular tunnel contains the double
track line has been chosen.The tunnel was
bored by TBM.
LINE 1 EXTENSION METROTORINO
GENERAL DESCRIPTION

Advantages of rubber wheels:
 Increased maximum slope (Easier track insertion in the city)
 Better acceleration/deceleration (Increased frequency of runs)
 Low vibrations and reduced noise (Better comfort)
Advantages of VAL system:
 Metro stations with reduced size
 Smaller tunnel section compared to traditional metro
VAL SYSTEM
Traditional metro
station (RRT metro)
150 m x 21m
VAL typical station
(LRT metro)
54 m x16,4 m
RRT – Rapid Rail Transit
LRT – Light Rail Transit
V0
P.R. P.R.
ASSE
V1
V2
ASSE

4
Roma B1 – NATM
excavation double way
(equivalent ø 11 m)
Torino –TBM bored
tunnel double way
(ø 7.78 m)
Copenhagen – TBM bored
tunnel single way
(ø 5.78 m)
Linea Diametro Canna
Superficie
sezione (mq)
Volume per
KM (mc)
Confronto
(mc)
Linea 1 Torin 7,78 1 47,51 47.514,79 0
Linea B1 Roma 11 1 94,99 94.985,00 47.470,21
Linea 2 Copenhagen 5,78 2 52,45 52.451,19 4.936,39
VAL SYSTEM

5
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) has TBM job site and the last (Lingotto) has train interchange
5 intermediate aeration shaft, built using micropilesShafts
CIVIL WORKS

 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).
GEOLOGY / GEOTECHNIC

 Utility relocation
 Job site alteration
 Diaphragms execution
 Station box execution
 Site cleaning and preparing for TBM
 TBM assembly
FIRST OPERATIONS

8
 Tecnological wires:
• Electric
• Telephonic
 Gas pipe
 Acqueducts
 Sewer
 Parking
 Monuments
 Other
UTILITY RELOCATION

GREEN MANAGEMENTS
Ante-operam activities:
 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 and phytopathological status
 Evaluation of the possibility of relocating the trees in original site, at the end of
the works.
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.

Criticality
 Short period between notice to award and operation;
 Saturated market bearings from eolic request;
 High risk of failure of procurement.
EPB PROCUREMENT
Countermeasures
 Market investigation about new TBM availability;
 Market investigation about used TBM availability;
 Risk plan to manage the acquisition.
Solution
Used TBM from job site in Paris with contingency plan for
refurbishment of machine.
Previous projects:
 France – Tolosa 2003 -2005 Metro project [5.600m]
 France – Parigi 2006 – 2007 Water reservoir [1.800m]

Main refurbishment works:
 Bearing inspection and service
 Service of cutter-head
 Service of screw conveyor
 Change of belt
 Cylinder pressures tests
 Certification of tanks (water and oil)
 Certification of hyperbaric chamber
 Replacement of suctions sealing
 Replacement of cables
 Replacement of guidance and operation system
 Replacement of pressures cells
EPB PROCUREMENT

 Tunnel excavation diameter : 7.78 mt
 Ring external diameter : 7.48 mt
 Ring internal diameter : 6.88 mt
 Number of segments : 5 + 1 (key segment)
 Segments tickness : 30 cm
 Average segment length : 1.40 mt
 Minimum track radius: 261.8 mt
THE RING

Several methods employed on Metrotorino
METHOD OF LECA & DORMIEUX (1990)
This method is based on the upper and lower limit theorems with a 3D-
modelling. The upper(+) and lower (-) limit solutions are obtained by means of
a cinematic and a static method, respectively, giving thus an optimistic and a
pessimistic estimation of the face-support pressure. In the case of dry
condition, the face support pressure σT is (Ribacchi 1994):
σT = – c’ · ctgϕ’ + Qγ · γ · D/2 + Qs · (σs + c’ · ctgϕ’)
where Qγ, Qs = non dimensional factors (from normograms), function of H/a
and ϕ’; a = radius of the tunnel; H = thickness of the ground above the tunnel
axis.
METHOD OF JANCSECZ & STEINER (1994)
According to the model of Horn (1961), the three-dimensional failure scheme
consists of a soil wedge (lower part) and a soil silo (upper part). The vertical
pressure resulting from the silo and acting on the soil wedge is calculated
according to Terzaghi’s solution.
A three-dimensional earth pressure coefficient ka3 is defined as:
ka3 = (sinβ · cos · – cos2β · tanφ – K · α · cosβ · tanφ/1.5)/(sinβ · cosβ
+ sin2β · tanφ)
where:
K ≈ [1 – sinφ + tan2(45 + φ/2)]/2;
α = (1 + 3 · t/D)/(1 + 2 · t/D).
METHOD OF ANOGNOSTOU & KOVARI (1996)
This method, later referred to as A-K method, is based on the silo theory
(Janssen 1895) and to the three-dimensional model of sliding mechanism
proposed by Horn (1961). The analysis is performed in drained condition, and a
difference between the stabilizing water pressure and effective pressure in the
plenum of an EPBS is presented. If there is a difference between the water
pressure in the plenum and that in the ground, destabilizing seepage forces
occur and a higher effective pressure is required at the face.
However, accepting this flow, the total stabilizing pressure is lower than the
pressure required in the case of an imposed hydrogeological balance. The
effective stabilizing pressure (σ’) :
σ’ = F0 · γ’ · D – F1 · c’ + F2 · γ’ · Δh – F3 · c’ · Δh/D
where F0,F1,F2,F3 are non-dimensional factors derived from
normograms, which are function of H/D and ϕ’.
DESIGN PHASE - SUPPORT PRESSURE CALCULATION

MetroTorino [kPa]20'
wvakP
Past experiences in Japan (from Kanayasu)
METHOD OF DIN 4085 (GERMAN STANDARD)
In this model, three-dimensional active earth pressure is calculated according to DIN 4085,
which is based on the failure mechanism theory of Piaskowski & Kowalewski. The method
divides the tunnel face into multiple horizontal strips. The three-dimensional active earth
pressure acting on each strip is calculated with the two-dimensional active earth pressure
method, adjusted by reduction factors. These factors are calculated depending upon the ratio
of depth of the layer to tunnel diameter.
To ensure stability of the tunnel face, it is necessary to counterbalance the total force of active
earth and water pressure. These forces are multiplied separately with safety factors as per the
concept of partial factor of safety
Psupport= η a E a + η w W
Where, η a and η w are partial factors of safety for active earth pressure (Ea) and water
pressure (W) respectively.
Several methods employed on Metrotorino

10
20
30
40
50
60
70
80
90
100
110
120
1097 1147 1197 1247 1297
Pressure[kPa]
Chainage [m]
Support pressure - Calculations using different methods
Spinta attiva Ka
Spinta a riposo
Ko
DIN 4085
Anagnostou &
Kovari
Leca-Dormieux
Normativa
olandese COB
Jancsecz &
Steiner
PL2
SHAFT
NIZZA
STATION

SENSOR LAYOUT
Warning Pressure in working
chamber
Attention Po = 0.9 Pd Po = 1.2 Pd
Alarm Po = 0.8 Pd Po = 1.3 Pd
CONSTRUCTION PHASE - SUPPORT PRESSURE MANAGEMENT

The main requirements a TBM should have to work in a urban
environment can be connected to:
Suitability to the anticipated geological conditions
Applicability of supplementary supporting methods, if necessary
Tunnel alignment and length
Equipments to realize tests, surveys or additional treatments
inwards;
Availability of equipments necessary to control the excavation
head pressure;
Availability of spaces necessary for auxiliary facilities behind the
machine and around the access tunnels
Interaction with monitoring parameters;
Safety of tunnelling and other related works.
Assembling, maintenance and disassembling flexibility;
Driving flexibility.
EPB PROCUREMENT
The final choice of machine is always a
compromise in which one of the key
parameters is the speed of excavation.

The correct project and development of the soil stability system is extremely important.
To guarantee the pressure control at the head of the front and to allow the formation of a
material easy to be extracted from the screw conveyor it is necessary to put conditioning
agents in the excavated soil, such as bentonite, foaming agents, polymers and thin material.
In our case, we wear the TBM with a separate circuit of emergency injection of bentonite to
avoid loosing pressure and settlements.

SOIL CONDITIONIG

SLUMP TESTS
Several tests were conducted on
conditioned samples employing differents
products with different solution
percentage (FIR; FER; etc..)

SCREW CONVEYOR EXTRACTION TEST
According to EFNARC (”Specification and
Guidelines for the use of specialist
products for Mechanised Tunnelling “), the
following aspects need to be examined:
• The plasticity of the soil, needed to
transmit the pressure inside the
working chamber and along the screw
conveyor
• A low internal friction of the
soil, needed to reduce the torque of the
cutterhead and the wear of the cutter
instruments
• The persistence of the carachteristics
described above over the time, to allow
the execution of operational procedures
(ring mounting, stops not
foreseen, etc..) in safer way.

SOIL CONDITIONING
Natural soil
Conditioned soil
CONDITIONED SOIL
FER = 18
FIR = 25%
• Pressure transmissions are uniform and regular
• Pressure is dissipated in regular way inside the screw conveyor
• The thorque force is reduced

PENETRATION RATE [mm/min]
PRESSURE SENSORS [Bar]
SCREW CONVEYOR RATE [rpm]
EXCAVATIONS PARAMETERS
Over 100 parameters recorded by the automatic system.
The main parameters to be verified via the sensors and sensing
equipment, are:
• Face-support pressure
• Pressure and volume of the backfill grout of the annular void
• Weight of the extracted material
EXCAVATION PHASE
OPERATIONS – BUILDING RING

Head support pression Penetration speed
Extracted material weight Pression of the mortar injection ducts
Example of TBM parameter monitoring

EPB –TBM OPERATION MODE

END EXCAVATION PHASE
END EXCAVATION PHASE
PRESSURIZED AIR/FOAM INFLOW
SCREW CONVEYOR STOPPED
PRESSURE INCREASE

Definition of normal and anomalous conditions
Normal excavating conditions
All those conditions whose EPB excavation characteristic parameters fall within the “attention” thresholds
Anomalous conditions are associated with:
 Water inflows under pressure through the screw conveyor.
 Sudden oscillations of the torque of the cutterhead.
 Blockage of the cutterhead.
 Anomalous pressure values in the excavation chamber.
 Sudden and significant variations of the muck density in the excavation chamber.
 Weight of the muck extracted by the screw conveyor surpassing the “attention” threshold.
 Insufficient pressure and/or volume of the grout injected behind the lining.
Pressure management in the work chamber
Sudden variations of the face-support pressure could be the warning signals resulting from torque increases or head blockages.
In case the pressure increases:
 The head rotating speed is reduced to <1 rpm.
 The thrust is reduced so that penetration rate, Vp, is <10 mm/min.
 The foam flow is increased by 20%,without increasing the muck discharge from the screw.
In case the pressure diminishes:
 Bentonite is injected to re-establish the design support pressure.
 If pressure still does not increase, excavation is stopped and the screw gate is closed.
 Bentonite and polymer injection is continued until the designed support-pressure is achieved.

WEIGHT MEASUREMENTS
CONSTRUCTION PHASE - WEIGHT MANAGEMENT
Material density was calculated as the average density measured on the last ten rings.
Double weight measurement :
 Scales on belt
 Scales on wagon
Special method
statement, additional
investigation
SOVRAESTRAZIONE STOP
NO
SI
ANALISI MATERIALE
ESTRATTO
Peso del materiale estratto dalla coclea oltre i
limiti di allarme +/- 5%.
INVESTIGAZIONE DA
INTERNO GALLERIA -
CAROTAGGIO CONCIO
PRESENZA DI
VUOTI
SI
RIEMPIMENTO
DALL’INTERNO / INIEZIONE
SECONDARIA
NO
REDAZIONE PROGRAMMA
INVESTIGAZIONE
DALL’ALTO (IM) E
PERFORAZIONE
CASO B)
INTERESSA DUE O PIÙ’ ANELLI CONSECUTIVI
RIEMPIMENTO DALL’ALTO A
GRAVITA’ CON MALTA
RIPRISTINO CONCIO
SI
VOLUME MALTA INIETTATA
>
VOLUME TEORICO PERFORAZIONE
PERFORAZIONE INTERNO
GALLERIA E INIEZIONE IN
PRESSIONE
RIPRISTINO CONCIO
Sovraestrazione misurata alla bilancia deL nastro
confermata da bilancia di controllo su: carroponte/
carosello, sui cassoni.
RITARATURA BILANCIA SU
NASTRO
NO
SI
STOP
STOP
NO
Volume e pressione di
iniezione malta
superano le soglie di
allarme inf. e sup.
Volume e pressione di
iniezione malta superano
le soglie di allarme inf. e
sup.
CASO A)
INTERESSA UN SOLO ANELLO E VIENE BILANCIATA DA
SOTTOESTRAZIONE ANELLO SUCCESSIVO
NO
NO
STOP
SI
SI
CASO A) O CASO B)
DA DECIDERE IN CONTRADDITTORIO CON LA DIREZIONE LAVORI

The correct choice of the TBM is the first step to manage the
excavation. Then it s necessary to identify and define the other
equipments to be used, depending of job site conditions such as:
 Tower crane for materials feeding
 Electric fan for aeration 135 kW
 Cooling tower
 Gantry crane for lifting muck
 Trains or Dumper for segments feeding
 Water treatment plant (10 mc/h)
 Winch for conveyor belt
 Electrical transfomer 22.000/20.000 V
 Emergency electric generator 400 kW
 Mixers for mortar, compressors
EPB ANCILLARIES PLANTS

30

WORKSITE LAYOUT – STARTING SITE

Much removal
WORKSITE LAYOUT – STARTING SITE

TBM
Transport belt to
TBM starting site
Wagons and fixed
crane
Load and
transport
temporary area
Surface
temporary depot
Discharge and
creation of piles
in the
operational lots
Trasport to final
destination
36
MUCK MANAGEMENT

37
 Two entrances and one lift for each station
 Station sizes 54x17m;
 Station deep from 20 to 25m;
STATIONS GEOMETRY

38
TOP DOWN SEQUENCE
STATION CONSTRUCTION PHASES

UTILITY RELOCATION

SITE CLEANING

EXECUTION OF GUIDE WALLS

EXCAVATION OF DIAPHRAGMS

REINFORCEMENT

POURING OF CONCRETE

DEMOLITION OF TOP HEAD OF
DIAPHRAGMS

TOP SLAB REINFORCEMENT

WATERPROOFING

EXCAVATION OF STATION

55
EXCAVATION OF STATION - USE OF STRUTS

BOTTOM SLAB REINFORCEMENT

TBM SUPPORTING SADDLE

DIAPRHAGM DEMOLITION FOR TBM
START

PUSH PORTAL
TBM START

USE OF STEEL SEGMENT IN
STATIONS
TBM START

61
To avoid water inflow
Bottom grouting
Break Out TBM
Break In TBM
SOIL IMPROVMENT

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.
To reduce settlements
SOIL IMPROVEMENT

STRUCTURAL MONITORING
 TENSION (STRAIN GAUGES, LOAD CELLS, etc.)
 DEFORMATION, SETTLEMENT
(INCLINOMETERS, OPTICAL TARGET, etc.)
BE: Strain gauge
CTC: Optical target
IN: Inclinometer
MONITORING

64
MONITORING
BUILDING MONITORING

65
Automatic monitoring with
electrolevels : the distortions
measured during the excavation
phase was less than the
established trigger levels
Example of monitoring during the excavation of part of the work adjacent to the buildings
MONITORING

66
NOISE
In the following chart have been highlighted the reference
and results with the trends and the PM10 limits exceeding.
AIR
VIBRATION
The noise monitoring campaigns was carried out on 20 receptors with:
 39 measurements semi-fixed workstations;
 41 measurements fixed workstations;
 15 short period measurements, living environment.
The vibration monitoring campaigns was realized on 14 receptors:
 37 short period measurements
 10 long period measurements (24 hours)
MONITORING

Cleaning of
pavements where
there is the
vehicles transit;
maintenance of
clearing brushes, etc.
Optimization of pumps
acoustic insulation,
etc.
Monitoring campaigns
Comparison of the results obtained with the
threshold limits
Threshold limits
exceeded
Threshold limits met
Open af an anomaly:
Analysis of the possible causes which produced
the criticality and prompt execution of the
mitigation interventions to solve and/or control
the problems occurred
Examples of mitigation
intervention realized
ENVIRONMENTAL PROCEDURE

CONSTRUCTION PROBLEMS – TOOLS UNDERPERFORMANCE
EXCAVATION CHAMBER INSPECTION

First stretch Marconi - Nizza
 96 tools added or changed
 More than 250.000 Euro damages
CONSTRUCTION PROBLEMS – TOOLS UNDERPERFORMANCE

Head at arrive in Nizza Station Head after refurbishment
CONSTRUCTION PROBLEMS – TBM HEAD DESIGN

CONSTRUCTION PROBLEMS – TBM HEAD DESIGN

Empirical methods are used to assess the settlements using
formulas that are based on empirical relations between available
data. This data has been collected and assessed by a lot of
researchers and for a lot of different projects.
Peck (1969) was the first to propose that the surface
settlement profile could be represented by a Gaussian
distribution curve.
In Turin Metro
volume loss was
usually about
0.3-0.5%
BUILDING RISK ASSESSMENT

Paratie con solettone copertura e piano atrio di contrasto
-2.0
-1.5
-1.0
-0.5
0.0
141516171819202122232425262728
Distanza fondazioni-paratia [m]
Cedimento[mm]

-3.7
Volume perso [%] 1
Diametro Galleria [m] 7.90
Copertura [m] 10 0.00
Parametro K 0.375 -0.85
Distanza tra gli assi [m] 0 0.000309
-
Ascissa SX edificio [m] -24.4 0.036551
Ascissa DX edificio [m] -9.4 0.00
Altezza [m] 7.1
Rapporto E/G 12.5 0.046273
0.000000
0.050410
0.00
0.050410
1
EPS MAX flex hog 0.0007816
EPS MAX flex sag 0.0016316
EPS MAX tag hog 0.0006761
EPS MAX tag sag 0.0014412
Epsilon terreno Hogging [%]
DATI DI INPUT
Cedimento massimo singola canna [cm]
OUTPUT
Interferenza n° 1000
Cedimento vertice SX [cm]
Cedimento vertice DX[cm]
Rapporto /L zona di Hogging
Rapporto /L zona di Sagging
CATEGORIA DI DANNO
Epsilon terreno Sagging [%]
Epsilon flessionale Hogging [%]
Epsilon flessionale Sagging [%]
EPSILON MASSIMA
Epsilon Tagliante Hogging [%]
Epsilon Tagliante Sagging [%]
Deformazioni Epsilon [%]
-0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
-20 -15 -10 -5 0 5 10 15 20
Canna sx
Canna dx
Totale
Cedimenti [cm]
-4
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
0.5
-20 -15 -10 -5 0 5 10 15 20
Canna sx
Canna dx
Totale
Settlements calculation : Building damage assessment

CASE HISTORY
Settlements associated with buildings n 0973, 0974
CASE HISTORY - SETTLEMENT ON BUILDINGS NEAR SPEZIA STATION

Buildings 973 - 974 : Masonry structures with direct
foundations on stone walls
SITUATION «ANTE OPERAM»

973
974
973
974
MITIGATION MEASURES – SOIL INJECTIONS

SETTLEMENTS DURING INJECTIONS PHASE

79

ADDITIONAL INVESTIGATIONS

Presence of thick layers of silty-sandy-clay having
behaviour "sensitive", with metastable microstructures sensitive t
o changes in stress or strains. The microstructure
metastable, stressed beyond a critical threshold level, it ceases
to behave in an elastic way, coming to be affected by phenomena
of destructuring, with significant loss of mechanical properties
(generation of irreversible visco-plastic deformation ).
In fact, it can be observed, that the oedometric curves referred at
the end of primary consolidation and 24 hours after the load
application are significantly different.
ADDITIONAL INVESTIGATIONS

DESTRUCTURED
SOIL
F.E. MODEL (PLAXIS SOFTWARE)

NUMERICAL MODEL CALIBRATION
SETTLEMENT AFTER INJECTIONS PHASE
SETTLEMENT FROM F.E. MODEL
PREVISION FROM F.E. MODEL
SETTLEMENT AFTER TBM EXCAVATION -
WITHOUT MICROPILES SHIELD
SETTLEMENT AFTER TBM EXCAVATION -
WITH MICROPILES SHIELD

974
TtestTcritico
25m
TBM MANAGEMENT
During the excavation of the test
section and the critical
section, we had to give particular
attention to the excavations
procedures with reference to:
Soil weight extracted from the
TBM;
Support pressure at the face;
Grouting behind the segments
(pressure and volume);
Bentonite injections around the
shield;
Additional mitigations:
Immediate availability of drilling
equipment for investigations from
surface.
Possibility to execute radial
injections from the tunnel, at the
end of shield

• Settlement during TBM excavation – Effects on stability of the buildings
EXCAVATION
MANAGEMENT
MECHANIZED
EXCAVATION
MONITORING
STOP EXCAVATION
MONITORING > L alert
MONITORING OK
EXPERTS COMMITEE
(CONTRACTOR;
OWNER;CONSULTANTS)
NEW PROCEDURE
NEW COUNTER
MESURES
Work Procedure - Ttest

EXCAVATION
MANAGEMENT
MECHANIZED
EXCAVATION
MONITORING
STOP EXCAVATION
(with working
chamber in pressure)
MONITORING >Lalarm
MONITORING OK
NEW PROCEDURE
NEW COUNTER
MESURES
BUILDINGS
EVACUATION
MONITORING >Lalert
MANAGEMENT
OWNER, MUNICIPALITY.
Work Procedure - Tcritico

 Topographic leveling executed 3 times a day (6:00 am - 14:00 -22:00). Monitoring
data available two hours after the end of leveling.
 Clinometers and crackmeters (manual readings) recorded once a day.
 Installation of 12 crackmeters (automatic readings) to monitor effects induced by TBM
excavation on existing cracks in "real time“
 The reading of the total station has take place every 30 minutes and the return on the GIS
platform with a frequency of 1 hour.
 Monitoring data available at the end of each ring excavation.
 It has been installed n.2 vibrometers on buildings 0973, 0974
MONITORING

MONITORING

Example: existing sanitary sewer
CASE HISTORY - INTERFERENCES WITH THE SEWERS

Interferences with subservices
Example: existing sanitary sewer

Interferences with subservices
Example: rain water sewer

CASE HISTORY - SHAFT CONSTRUCTION

Problems during construction:
• Flood in shaft – Effect on tunnel connection
CASE HISTORY - SHAFT CONSTRUCTION

INITIAL SITUATION
CASE HISTORY - FLOOD IN DANTE STATION
…AFTER FEW HOURS

• Flood in station – Effects on TBM schedule
CASE HISTORY - FLOOD IN DANTE STATION

• TBM in/out does not perform – Effects on stability, flood in station and launch of TBM
Tests to check permeability value TBM In - Supplementary injections to reduce
water inflow
CASE HISTORY - BREAK IN / OUT

• TBM in/out does not perform – Effects on stability, flood in station and launch of TBM
TBM Out - Supplementary injections TBM Out – Sealing System to start excavation
CASE HISTORY - BREAK IN / OUT

CASE HISTORY - NICHE CONSTRUCTION

Tunnelling is not a risk-free technology, each tunnel is a specific unique project on its own in a unique combination of
ground / soil. The “right” construction method with the “right” experience parties involved are crucial for the success.
The main most important factor however, the geology, is only known to a limited extent. Any accident during construction as well
as in use provokes a substantial interruption and often a standstill till the problems are solved.
Risk has two components: probability of occurrence W and amount
of damage D.
The different steps of the process are:
 Identification of the risks (initial one);
 Reduction of the initial risk working on the impact and/or
possibility of occurrence of an event (i.e. provisional building
works, choice of the machinery, control of the TBM head
pression);
 Management of the residual risk (i.e. monitoring).
Residual risks are unavoidable and they should be shared
among the Parties and systematically controlled by
countermeasures.
CONCLUSIONS

The residual risk have to be managed during the construction
phase by means of an integrated monitoring system to:
 Check the hypothesis used during the desig ohase;
 Allows to understand the atypical phenomena giving the
information necessary to solve the problem.
The project must define two parameters which identify the
“attention” and “alarm” levels.
Attention level activates a specific control system in order to
reach a more specific following of the event.
Alarm level requires the adoption of the counter-measures
specifically studied for the event.
Topographical controls on buildings
CONCLUSIONS

The extension of MetroTorino has take account of a multidisciplinary approach that
considers all the processes of the entire lifecycle and performance of the works.
The integrated methodological approach, implemented in the execution of projects and
works of construction into urban areas, must necessarily involve the adoption of a process of
continual revision of the initial assumptions of the design, through the continuous
analysis of monitoring data for proper risk management.
CONCLUSIONS

START: 08.01.2007
Finishing date (CONTRACTUAL) : 03.05.2010
Finishing date (REAL) : 03.02.2010
AWARDS

Rome
Via di Vannina, 88/94
00156 Rome
Ph. +39 06 4122 351
Fax +39 06 4122 35610
Milan
Viale Monte Grappa, 3
20124 Milan
Ph. +39 02 6313.1
Fax. +39 02 6313.9052
Turin
Corso Ferrucci, 112/a
10138 Turin
Ph. +39 011 00.56.1
Fax +39 011 00.56.444
Florence
Viale L. Ariosto 24/b
50124 Florence
Ph. +39 055 2280 609
Fax +39 055 2335 517
info@mairetecnimont.it – www.mairetecnimont.it

Metro Torino Extension - Design and construction problems

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