Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case...

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Case history of hard rock TBM La Maddalena exploratory adit for the TurinLyon high speed railway base tunnel E. Fornari, G. Russo, L. Ferrero Mechanized Tunnelling: challenging case histories 1st December 2016 ‐ Rome

Transcript of Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case...

Page 1: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

Case history of hard rock TBMLa Maddalena exploratory adit for the

Turin‐Lyon high speed railway base tunnel

E. Fornari, G. Russo, L. Ferrero

Mechanized Tunnelling: challenging case histories1st December 2016 ‐ Rome

Page 2: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

The HSR network in Europe: like a giant Metro‐System connecting main cities

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M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

SEVILLE

BUDAPEST

The “Mediterranean Corridor” will connect Seville (Spain) to Budapest (Hungary).

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M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

SEVILLE

BUDAPESTLYON

TURIN

The Turin‐Lyon high‐speed rail project is halfway along the future“Mediterranean Corridor” from Seville (Spain) to Budapest (Hungary).

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The Turin‐Lyon HSR project includes:• French section, between Saint‐Didier‐de‐la‐Tour (East Lyon) and Saint‐Jean‐de‐Maurienne, managed by RFF;• International section (France‐Italy), which crosses the Alps between Saint‐Jean‐de‐Maurienne (France) and Susa

(Italy), managed by a bi‐national agency (TELT‐ Tunnel Euralpin Lyon Turin) governed by Italian and French gov.;• Italian section, from Susa to outskirts of Turin, managed by Italian RFI.

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

BASE TUNNEL (57 km)

The project includes a 57 km‐long Alpine base tunnel, whose construction will be starting soon.

Open air section

Tunnel section

New stations

Safety site

approx. 170 by-passes (every 333 m)4 intermediate vehicular accesses

Diam. 8.40 m43 m²

Tunnel section

25 to 40 mSAINT JEAN DE

MAURIENNE

SUSA

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FRANCE ITALY

Saint‐Martin‐La‐Porte (2.4 km)

La Praz(2.5 km) 

Villarodin‐Bourget/ Modane (4.0 km)

La Maddalena (7.5 km)

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

La Maddalena (7.5 km)

The base tunnel has four adits:‐ three in France (all completed) ‐ one in Italy (under completion) – La Maddalena.

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BASE TUNNEL

« LA MADDALENA »EXPLORATORY ADIT

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

Scope of «La Maddalena» exploratory adit:

• Investigation of rock mass and  TBMperformance for detail design of base  tunnel

• Construction of  «Clarea» safetycavern on base tunnel

• Access to base tunnel for maintenance or emergency

Plan view

Page 8: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

«GEA» Main Beam TBM (Robbins MB1812‐299‐2)

Machine Diameter 6.30m

Overboring 0.1‐ 0.2m

Number of disc cutters 43 (17’’)

Maximum Recommended Individual Cutter Load 311kN

Normal Operating Cutterhead Thrust @4200PSI 12,756kN

Periodic Maximum Cutterhead Thrust @4500PSI 13,667kN

Cutterhead Drive 7 electric motors, gear reducers and brake

Cutterhead Power 2,954HP

Cutterhead Speed 0‐10.8rpm

Cutterhead Torque @ 10.8 rpm 2,083kNm

Stroke 1.83m

Number of Main Thrust Cylinders 4

TBM weight (approx.) 250 ton

Page 9: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

Main beam TBM assembly under telescopic shed at tunnel entrance

Page 10: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

ch. 6+500

6,500 m excavated 

BASE TUNNEL

« LA MADDALENA »EXPLORATORY ADIT

Present state of “La Maddalena” construction

Page 11: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

Quaternary depositsTectonic carbonatic rocksAmbin Rock complex (Aplitic Gneiss)Ambin Rock complex (Quartzitic Micaschists)Clarea Rock complex (Micaschists)

0+0005+000

500m asl

1,500

2,500

2,000

1,000

??

4+000

??

?

1+0002+0003+000

?

?

6+0007+000

chainage 6+500Overburden approx. 1,910 m

Max

overbu

rden

2,01

2 m

Schematic geological profile

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M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

I6.1%

II46.1%

III47.1%

IV0.7%

AS‐BUILT – RMR

I

II

III

IV

MAX RMR: 98

MAX GSI: 98

MAX c: 236MPa (lab test)

Extremely hard and abrasive rock mass Rock mass rated fair (III) to good (II)

Page 13: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

12

1.0

15.0

28.022.0

13.018.0

4.0 6.0

20.0 17.011.0

16.0 19.013.0

19.0 22.029.0

39.0

71.0

58.0 57.0 61.0

29.0

41.0

53.0 55.0 58.0

172,47

0

25

50

75

100

125

150

175

200

0

5

10

15

20Novem

ber 2

013

Decembe

r 2013

Janu

ary 2014

February 2014

March 2014

April 2014

May 2014

June

 2014

July 2014

August 2014

Septem

ber 2

014

Octob

er 2014

Novem

ber 2

014

Decembe

r 2014

Janu

ary 2015

February 2015

March 2015

April 2015

May 2015

June

 2015

July 2015

August 2015

Septem

ber 2

015

Octob

er 2015

Novem

ber 2

015

Decembe

r 2015

Janu

ary 2016

February 2016

March 2016

April 2016

May 2016

June

 2016

July 2016

August  2016

Chan

ges/week ‐C

hanges/m

onth ‐m

3 /cutter

Chan

ges

Date

CUTTER CONSUMPTIONLA MADDALENA PILOT TUNNEL

TBM "GEA"

Changes per 1 day

Changes per 7 days

Changes per 30 days

Cutter consumption

m3/cutter

Page 14: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

19,1%OCCASIONAL

BOLTING

21,6%SYSTEMATIC

BOLTING

38,5%LIGHT

STEEL RIBS

20,8%HEAVY

STEEL RIBS

LONGITUDINAL STEEL RE-BARS AT TUNNEL CROWN

LENGTH

 (m)

SUPPORT

Page 15: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

9%

12%

20% 23%

22%

22% 24%

25%

18%

18%

17% 19%

20%

19%

30%

28%

26% 28% 30% 32%

32%

32%

33% 35%

35%

35%

51%

60%

60% 61%

58%

56%

57%

58%

56%

54%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Novem

ber 2

013

Decembe

r 2013

Janu

ary 2014

February 2014

March 2014

April 2014

May 2014

June

 2014

July 2014

August 2014

Septem

ber 2

014

Octob

er 2014

Novem

ber 2

014

Decembe

r 2014

Janu

ary 2015

February 2015

March 2015

April 2015

May 2015

June

 2015

July 2015

August 2015

Septem

ber 2

015

Octob

er 2015

Novem

ber 2

015

Decembe

r 2015

Janu

ary 2016

February 2016

March 2016

April 2016

May 2016

June

 2016

July 2016

August 2016

Septem

ber 2

016

Octob

er 2016

Percen

tage

use of TBM

Month

PERCENTAGE USE OF TBM2013 ‐ 2016

LA MADDALENA PILOT TUNNELTBM "GEA"

o 4 SHIFT TEAMS (EXCAVATION 24h 7d/w)o LONGITUDINAL STEEL RE‐BARS AT 

TUNNEL CROWN 

Page 16: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

WEEKLY HOURS AVAILABLE FOR EXCAVATION

HOURS WORKEDPER WEEK

LABOUR AVAILABILITY

3 SHIFT TEAMS(exc. 24h/d 6d/w)

168124 73.8%

4 SHIFT TEAMS(exc. 24h/d 7d/w) 168 100%

4 SHIFT TEAMS vs. 3 SHIFT TEAMS:HOURS AVAILABLE FOR EXCAVATION

+35,5%

Page 17: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m eG. Russo, 2014

Observed behaviour of rock mass

Page 18: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

Effects from stress release were evidenteven with relatively low overburden (lessthan 400m).

Stand‐up time in unsupported rockbegan to be systematically shorter thanusually experienced (Bieniawski, 1989).Excavation often proceeded withrelatively low TBM thrust on the face,leaving broken rock at tunnel crown.

Page 19: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

Z.T. Bieniawski, 1989

Page 20: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

1.0E+00

1.0E+01

1.0E+02

1.0E+03

1.0E+04

1.0E+05

1.0E+06

0 10 20 30 40 50 60 70 80 90 100

Stan

d‐up

 time for 6

 m ro

ofspan

(hrs)

RMR

Bieniawski '89 – Stand‐up time

Page 21: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

1.0E+00

1.0E+01

1.0E+02

1.0E+03

1.0E+04

1.0E+05

1.0E+06

0 10 20 30 40 50 60 70 80 90 100

Stan

d‐up

 time for 6

 m ro

ofspan

(hrs)

RMR

Bieniawski '89 ‐ Stand‐up time (TBM)Brittle failureStableInstable wedgesUnstable wedges

Page 22: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

Production now safely proceeds with installation of circumferential steel ribs connected with 120°arch of longitudinal steel re‐bars

Lesson learnt: new type of support with circumferentialsteel ribs and longitudinal steel re‐bars

Page 23: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

Page 24: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

0

2000

4000

6000

8000

10000

12000

0

5

10

15

20

25

30

35

1+000 1+020 1+040 1+060 1+080 1+100

Force (kN) ‐

Torque

 (kN‐m

)

Rate of p

enetratio

n (m

m/m

in) ‐

Rotatio

n speed (rpm

)From 1+000 to 1+100

Torque

ROP

Rotation speed

Thrust

0

2000

4000

6000

8000

10000

12000

0

5

10

15

20

25

30

35

5+500 5+520 5+540 5+560 5+580 5+600

Force (kN) ‐

Torque

 (kN‐m

)

Rate of p

enetratio

n (m

m/m

in) ‐

Rotatio

n speed (rpm

)

From 5+500 to 5+600

Torque

ROP

Rotation speed

Thrust

Less work required to excavate with brittle failure at face

Page 25: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

The most important brittle failure eventoccurred at 11 p.m. of 21/12/2015 aroundch. 4+200 having a visible effect on supportfor a length of 10‐12m of excavated tunnel

The rock mass, classified RMR = 61‐72 andGSI = 62‐75, presented subhorizontalschistosity and open discontinuities oftenwith carbonate fill. Overburden was ofabout 1,000m

Workers heard a sudden smash. This wasaccompanied by large deformation ofsupports

Page 26: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

Significant rock fragmentation at crown (result of failure between new/existingdiscontinuities and schistosities)

Lesser disturbed conditions with generally stable sidewalls

Page 27: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

Rock fragmentation and observed behaviour correspond to a Bulking without ejection event(CRRP, 1996): the stored strain energy was consumed in the fracturing process, with significantincrease of volume due to dilatancy.There was no significant release of kinetic energy (rock ejection at high velocity).

Page 28: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

Numerical modelling Step 1: parametric analysis

(ko=0.3‐0.8‐1‐1.2; ...)

Step 2:  based on CSIRO tests results (niche 3) 

Likely scenario: Failure criterion 

"spalling" (Diederichs) ko = h/v = 1.2

Page 29: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

Deviatoric stress (1-3)a) Fracturing starts («damage»)

b) potential rockburst conditions

3D NUMERICAL ANALYSIS

Page 30: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

OBSERVED MECHANISM Fracturing (damage) starts near excavation face at crown and invert Potential rockburst conditions from about one diameter behind face Depth of damage is at max 1‐1.5m from excavated profile

Potential brittle failure

Face usually stable thanks to favourableorientation of schistosity

Page 31: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

Brittle failure events, from ch. 4+200 onwards, were less intense

Change in morphology/stress

ch. 4+900

Niche 3ch. 2+805

event atch. 4+200

Page 32: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

SUMMARY AND CONCLUSIONS

• Themain beam hard rock TBM used for La Maddalena exploratoryadit has excavated 6.5km in a rock mass (gneiss and micaschists)rated from fair to good and has reached the exceptionally highoverburden of 2,000m under Mount Ambin.

• Stress release effects, with fracturing and failures especially attunnel crown, have accompanied excavation since overburdenexceeded about 400m, when it was observed that stand‐up timesin unsupported rock began to be systematically shorter thanusually experienced (Bieniawski, 1989).

• Another side effect from stress release, with fracturing at tunnelface rather than at tunnel crown, was the reduction of TBMthrust, torque and head rotation velocity required for excavation.

• The type of brittle failure observed is of dilatant fracturing (or“bulking without ejection”), a rockburst mechanism withoutsignificant release of kinetic energy.

Page 33: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

M e c h a n i z e d   T u n n e l l i n g :   c h a l l e n g i n g   c a s e   h i s t o r i e s   – 0 1   D e c e m b e r   2 0 1 6   ‐ R o m e

SUMMARY AND CONCLUSIONS

• Only on one occasion, at the end of 2015 when overburden was ofthe order of 1,000m, rock mass bulking provoked largedeformations of tunnel steel rib supports.

• Even now, with 2,000m overburden, minor brittle failurecontinues to take place, always without violent rock ejections.

• Tunnel profile supports have since been adapted, by usingsystematic protection with a 120°arch of longitudinal steel re‐bars supported by circumferential steel ribs, a solution whichallows to continue excavation even when the rock mass at crownhas broken into fragments.

• The new supports brought to an immediate sustained increase ofpercentage of use of TBM (efficiency), from under 35% to over55%, allowing productions of about 12m/day as opposed to about4m/day in unstable crown conditions.

Page 34: Mechanized Tunnelling: challenging case histories · Mechanized Tunnelling: challenging case histories –01 December 2016 ‐Rome SUMMARYANDCONCLUSIONS • The main beam hard rock

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Mechanized Tunnelling: challenging case histories

1st December 2016 ‐ Rome