Mavi Tunnel Segments Presentationmavitunel.com/dosya/mtsegments.pdf · 2011. 7. 25. · -UNI ENV 1992-1-1 1993 EUROCODE 2: “Design of concrete structures”. Part 1-1: “General

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MAVI TUNNEL

SEGMENTS PRESENTATION

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- Boring diameter of the DS TBM: 4,88 m- Outer dia. of the segmental lining: 4,70 m

Hexagonal precast segmentsSegmental lining thickness: 0,25 mLongitudinal length: 1,30 m

- Inner dia. of the segmental lining: 4,20 m

GEOMETRY

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LINING OF HEXAGONAL PRECAST SEGMENTS

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PREDICTED HYDROGEOLOGICAL AND GEOMECHANICAL ROCK MASS FEATURES

From Doc. MT-13B (Konya-Cumra Project – III Phase)

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min med max min med max min med max min med maxI 270 0,549 0,831 1,327 29,9 36,5 42,2 2,94 4,82 7,85 1435 4725 15647

II 400 0,51 0,795 1,22 25,1 30,3 37,1 2,68 4,37 7,31 693 1423 4685

III 400 1,111 1,296 2,129 34,9 37,3 42,9 6,36 7,62 12,57 4161 6671 22092

IV 400 0,51 0,795 1,22 25,1 30,3 37,1 2,68 4,37 7,31 693 1423 4685

V 350 0,447 0,704 1,404 25,74 31,2 41,8 2,69 4,41 9,74 712 1463 9892

VI 300 0,62 0,96 1,63 30,9 37,6 43,11 3,83 6,3 10,36 1682 5540 18345

c (Mpa)Zone Overburden (m)

f (°) scm (Mpa) Em (Mpa)

Strength and deformation parameters estimated by means of Hoek & Brown failure criterion (2002 version)

ESTIMATED GEOTECHNICAL PROPERTIES OF ROCK MASSES

Refer to:

“Hoek, Carranza-Torres and Corkum (2002) – Hoek-Brown Failure Criterion – 2002 Edition. Proc. 5th North American Rock Mechanics Symposium, 1”.

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REINFORCING STEEL St 420 S (DIN 488) Characteristic yield strength of reinforcement fyk 420 MPa

Partial safety factor for reinforcement gs 1,15

Design yield strength of reinforcement s

yk

yd

ff

g= 365,22 MPa

Modulus of elasticity of reinforcement Es 200000 MPa

Thermal expansion’s ratio a 0,00001 °C-1

Reinforcement density r 7850 kg/m3

The structural verifications included in the present report refer to the followings codes and recommendations.

-UNI ENV 1992-1-1 1993 EUROCODE 2: “Design of concrete structures”. Part 1-1: “General rules and rules for buildings”-AFTES – Recommandations relatives a: l’utilisation du béton non armé en tunnel - version 1 – 1998

MATERIALS

CODES AND RECOMMENDATIONS

The following tables resume the main mechanical characteristics of the employed materials, evaluated according to Eurocode 2.

CONCRETE C35/45 (EC 2)

Characteristic value of cube compressive strength fck, cube 45 MPa

Characteristic value of cylindrical compressive strength fck 35 MPa

Partial safety factor for concrete gc 1,5

Design value of concrete compressive strength c

ckcd

ffg

= 23,33 MPa

Axial tensile strength of concrete (mean value) ( ) 3/23,0 ckctm ff ×= 3,21 MPa Axial tensile strength of concrete (5% fractile) ctmctk ff 7,005,0 = 2,25 MPa Axial tensile strength of concrete (95% fractile) ctmctk ff 3,195,0 = 4,17 MPa

Design axial tensile strength of concrete C

ctk

ctd

ff

g05,0= 1,5 MPa

Required tensile strength at demoulding fctks 0,80 MPa

Concrete secant modulus of elasticity ( ) 3/189500 +×=ckcm

fE 33282 MPa Poisson’s ratio n 0,2

Thermal expansion’s ratio a 0,00001 °C-1

Concrete density r 2500 kg/m3

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A) EXCAVATION PHASE: STATIC VERIFICATIONS BY MEANS OF CHARACTERISTICLINES METHOD-Rock mass – TBM shield system stability and segments tensions induced by externalrock loads are verified during excavation phase

B) WORKING PHASE:-Segments verifications with empty tunnel and maximum external load-Segments verifications with tunnel under internal pressure and minimal external load-Segments verifications with empty tunnel and prefixed external rock load (h=45m)-Segments verifications with empty tunnel and exceptional external load

C) MANUFACTURING AND INSTALLATION PHASES:-Segment demoulding phase-Storage on stock-Unloading and uploading-Transport to tunnel

EXAMINED PHASESGEOTECHNICAL AND STRUCTURAL VERIFICATIONS

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A) EXCAVATION PHASE - CHARACTERISTIC LINES METHOD

HYPOTHESES

-Segment and pea gravel are set up at a distance of 12 m (shield’s total length) from the excavation front.

-Contact grouting (with a pressure of 3 bar) is executed by the backup in every tunnel zone (I÷VI).

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A) EXCAVATION PHASE - CHARACTERISTIC LINES METHOD

RESULTS

Static verifications have been executed both with a 100 m external water load and withno water load to consider respectively the case without or with consolidation grouting.

The value of the water load has been estimated in consideration of the low rock masspermeability and must be verified during execution by means of drillings from excavationfront with a minimum length of 35 – 40 m.

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CONSOLIDATION GROUTING

Furthermore high pressure grouting will be executed to consolidate a layer of about 2-2,5m of the surrounding rock.

This consolidated layer will waterproof the tunnel and will adsorb, if necessary, the potentialexternal water load (zones II - III - IV and V).

Zones II-IV have been analyzed with or without consolidation grouting.

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B) WORKING PHASE

Two loads combinations have been considered as normal limit workingconditions:

-B1) Empty tunnel with maximum external load.

-B2) Tunnel with internal pressure (100 m hydrostatical) and minimalexternal load.

Other two loads combinations have been verified as representative ofexceptional conditions:

-B3) 45 m rock load acting on segments in radial direction.

-B4) Empty tunnel with external gravitational load acting at lining crowncombined with contact and consolidation grouting and potentialexternal water load (zones II and IV – case without consolidationgrouting).

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B1) WORKING PHASE - Empty tunnel with maximum external load

In zones I, III, V and VI the maximum external load is due to consolidation grouting pressures,executed after segments set up with a pressure of 11 bar (1100 kN/m2) and inducing tensions onthem of about 13 MPa.

In zones II and IV the maximum tensions on segments (of about 16 MPa with minimal geotechnicalparameters) are generated during excavation phase without consolidation grouting .

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B2) WORKING PHASE- Tunnel with internal pressure (100 m hydrostatical) and minimal external load.

-In zones I, III, V, VI and II-IV (with consolidation grouting) the maximum internal pressure(1000 kN/m2 ) is always balanced by the external load due to 11 bar (1100 kN/m2)consolidation grouting. In these conditions joints are always closed.

-In zones II and IV (without consolidation grouting) the maximum internal pressure (1000kN/m2) is contrasted, in the worst condition, by the external load due to 3 bar (300 kN/m2)contact grouting. Therefore segments opening has been verified with a net internal pressureof 700 kN/m2. The obtained opening width values, of about 5 mm for each joint, are widelyadmissible since the stability of the system of segments is guaranteed for openings lowerthan 150 mm.The hydraulic sealing is guaranteed by the surrounding rock mass, which presents lowpermeability and a strength capable to absorb this pressure.

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B2) WORKING PHASE- Tunnel with internal pressure (100 m hydrostatical) and minimal external load.

Radial deformation due to internal pressure

0,00

0,50

1,00

1,50

2,00

2,50

3,00

3,50

4,00

4,50

5,00

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1 1,1

Internal pressure [MPa]

Rad

ial d

efor

mat

ion

[mm

]

E=693 MPa E=1423 MPa E=4685 MPa

Opening width values of each joint with minimum rock elastic modulus (E = 693 MPa) = 3.1*2*3.14/4= 4.9 mm

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B3) WORKING PHASE - 45 m rock load acting on segments in radial direction.

-In zones I, III, V, VI and II-IV (with consolidation grouting) pressures on lining of 1170 kN/m2, whichgenerate compressive tension of about 14,1 MPa at the ULS, have been obtained.No external water load has been considered in these zones since absorbed by the consolidatedlayer of the surrounding rock mass.

-In zones II and IV (without consolidation grouting) pressures on lining of 1720 kN/m2, whichgenerate compressive tension of about 20,6 MPa at the ULS, have been obtained.An external hydrostatic load (100 m) has been considered for these zones.

-These pressures are the most unfavorable found in the executed verifications and therefore theyhave been used for light segments (p=1170 kN/m2) and for heavy segments (p=1720 kN/m2) design.

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B4) WORKING PHASE - Empty tunnel with external gravitational load, consolidation grouting and potentialexternal water load (zones II and IV – case without consolidation grouting).

The following loads have been considered:

-qo Potential gravitational load at tunnel’s crown evaluated with minimal geotechnical parameters-q1 Lining self weight-q2 External pressure due to contact grouting (300 KN/m2)-qest External pressures due to consolidation grouting for zones I,II, III,IV, V, VI (1100 kN/m2) -qest External water load for zones II and IV without consolidation grouting (1000 kN/m2)

The followings load combinations have been verified in order to maximize segments tensions:Loads combination 1 = (q0+q1+qest)Loads combination 2 = (q0+q1+q2)

The evaluation of the potential gravitational loads q0 at tunnel’s crown have been executed by means of the prominent UNAL relation (1983):((100-RMR)/100)x g x Dwhere:g = rock specific weight;D = excavation diameter = 4,88 m;

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B4) WORKING PHASE - Empty tunnel with external gravitational load, consolidation grouting and potentialexternal water load (zones II and IV – case without consolidation grouting)

ZONEq0 q1 q2 qest

Reinforcement LoadsCombinations

ULS stresses(b = 1,3 m)

ULS strength(b = 1,3 m)

FS[kN/m2] [kN/m2] [kN/m2] [kN/m2] M [kNm] N [kN] M [kNm] N [kN]

I 82,47 6,25 300 1100As=A's L.C. 1(q0+q1+qest) 121,29 4431 144,12 5266 1,19

8f10 L.C. 2(q0+q1+q2) 93,56 1343 231,44 3322 2,47

II 93,93 6,25 300 1000As=A's L.C. 1(q0+q1+qest) 141,80 4033 171,23 4870 1,21

8f10 L.C. 2(q0+q1+q2) 117,09 1331 232,77 2647 1,99

III 71,01 6,25 300 1100As=A's L.C. 1(q0+q1+qest) 107,02 4413 131,60 5427 1,23

8f10 L.C. 2(q0+q1+q2) 80,75 1322 223,78 3665 2,77

IV 93,93 6,25 300 1000As=A's L.C. 1(q0+q1+qest) 141,80 4033 171,23 4870 1,21

8f10 L.C. 2(q0+q1+q2) 117,09 1331 232,77 2647 1,99

V 90,32 6,25 300 1100As=A's L.C. 1(q0+q1+qest) 135,96 4437 156,24 5098 1,15

8f10 L.C. 2(q0+q1+q2) 112,41 1341 235,35 2808 2,09

VI 79,3 6,25 300 1100As=A's L.C. 1(q0+q1+qest) 117,48 4426 140,90 5308 1,20

8f10 L.C. 2(q0+q1+q2) 88,77 1339 228,86 3453 2,58

The segment is reinforced with 8f10 for each section side and it’s able to guarantee ULS safety factors greater than 1 for every zone, like shown in the following table:

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C) MANUFACTURING AND INSTALLAZION PHASES

- Segment demoulding phase

d LL 1 1 1d LL 1 1 1

-Storage on stock

L L

e

i

e2

22 2a

1

2

3

4

1

2

3

4

2 2

L Li 22 2a

1

2

3

4

e e2

1

2

3

4

e e

L i L 22 2a

22

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C) MANUFACTURING AND INSTALLAZION PHASES

-Unloading and uploading

a3

d3

a 3

d 3

-Transport to tunnel

L L

e

i

e44

44 4a

1

2

3

4

5

1

2

3

4

5 4

L Li 44 4a

1

2

e e4

1

2

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TBM THRUST FORCES

L p

F5P F5P F5P F5P

5P 5P

h 5P

Lm

b b

Verifications have been executed considering the thrust of 4 pistons on the upper segment of the lining (at tunnel’s crown). Two thrust values have been considered for light segments (zones I-II – III –IV- V – VI) and for heavy segments (zones II – IV - case without consolidation grouting).

For both segments type the safety factor are so verified (7,56 for light segments and 2,19 for heavy segments)

Calculations about minimum reinforcement necessary to absorb tensile actions generated by TBM thrust forces in tangential direction have been executed.

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MAVI TUNNEL PROJECT 21LONGITUDINAL JOINTS – STATIC VERIFICATIONS

Longitudinal joints compressive verifications have been executed for light and heavy segments with maximum pressures values deriving from the calculations.

For both segments type the safety factor are so verified (1,64 for light segments and 1,11 for heavy segments)

Calculations about minimum reinforcement necessary to absorb tensile stresses in radial direction have been executed.

Light segment I-II-III-IV-V-VI 1170 kN/m2

Heavy segment II-IV (without consolidation grouting)

1720 kN/m2

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BIBLIOGRAPHY

-M. PANET (1995) – Le calcul des tunnels par la méthode convergence – confinement - Presses de l’écolenationale des Ponts et Chaussées;

-G. LOMBARDI (July 1973) – Dimensioning of tunnel linings with regard to constructional procedure – Tunnelsand Tunnelling;

-W. A. AMBERG, G, LOMBARDI (1974) – Une méthode de calcul élasto-plastique de l’état de tension et dedéformation autour d’une cavité souterraine Partie II – 3rd Congr. ISRM - Denver;

-F. LEONHARDT / E. MONNIG (1977) - Casi Speciali di dimensionamento nelle costruzioni c.a. e c.a.p – Vol II;

-O. BELLUZZI (1977) – Scienza delle costruzioni – Vol. 1 – 4 – Zanichelli.