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28th August 2009 11
Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Graitery Tunnel
Use of ZSoil for complex excavations
Dominique TendonAldo BisettiJacques L’Eplattenier
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
A16 – Transjuranne
Graitery Tunnel Tunnel : L = 2’462 m
South portal: L = 18 m
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
N
Tunnel face
Axis
N16
Cut and cover tunnel
L = 18m
South portal excavation
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
South portal - initial project - Front excavation wall
Axe N16
Strand anchors
Bar anchors
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
History of excavation:
Mid 2007: Beginning of the excavation of the south portal of the GraiteryTunnel
October 2007: Movements of the front excavation wallIncrease in the tensile forces of the anchors
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
5th november 2007
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
History of excavation:
Mid 2007: Beginning of the excavation of the south portal of the GraiteryTunnel
October 2007: Movements of the front excavation wallIncrease in the tensile forces of the anchors
Novembre 2007: Reinforcement of front wall (more anchors are added) Excavation continues
The wall movements and the increase in anchor forces are nothindered
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Geodesic mesurements – Horizontal displacements
Embankment displacements Front wall displacement (top)
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Tensile forces in strand anchors
Pinitial = 500 kN
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
16th november 2007
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
History of excavation:
Mid 2007: Beginning of the excavation of the south portal of the GraiteryTunnel
October 2007: Movements of the front excavation wallIncrease in the tensile forces of the anchors
Novembre 2007: Reinforcement of front wall (more anchors are added) Excavation continues
The wall movements and the increase in anchor forces are nothindered
Mid-novembre 2007: Partial filling of the excavation to prevent an instability
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Décember 2007
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
January - April 2008: Complementary investigations (6 additional borings) More precise geological model
Important laboratory tests campagne carried out by the EPFL
Retrofit Stability analysis using ZSoil performed by GVH
Constant interaction between the geological model, the stabilityanalysis and the scope of the laboratory testing.
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Geology – Vertical section
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Retain structure front and lateral walls:
- strand anchors AVT 5T13, Pinitiale = 500 kN
- bar anchors GFK D25mm
- bar anchors GEWI D25mm
Colluvions
Fractured marnymolasse
Compact marny molasse
Limestone
Sandstone molasse
Investigation gallery
ZSoil 3D Model
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Ground water
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Level A: 1/2 AA15, AA14, AA13, AA12, AA11 et AA10
Level C:CA12, 1/2 CA11 et CA10
Level D:DA 10
Front wall Lateral wall
Level C:CA1, CA2, CA3 et CA4
Pretressed strand anchors
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Front wall
Lateral wall
Level B: 3 clousGEWI+ 3 GFK
Level C: 3.5 GFK
Level D: 4 clous GFK
Level E: 3.5 clous GFK
Level A: 2 GEWI
Bar anchors
Level B: 3 GEWI
Level D: 5GEWI
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Ancrages passifsDisplacements for C molasse marneuse = 20 kN/m2
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Ancrages passifsDisplacements for C molasse marneuse = 20 kN/m2
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Tensile forces in prestressed anchorsC molasse marneuse =20 kN/m2
Free portion
Fixed portion
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Adjustment of cohesion using mesured tensile forces in anchors
φ' = 16°
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Redesign of the south portal retaining structure
Front wall:Anchored pile wallFireglass reinforcement for piles within the tunnel build
Lateral walls:Secant anchored pile walls
Embankment above tunnel:Permanent prestressed anchors
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Models for the design of the retaining structures:
2D models for design of piles
2D model for stability of lateral walls
2.5D model for stability of front wall
3D model for acknowledgement of previous results
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
ZSoil 3D Model
Colluvions
Fractured marnymolasse
Limestone
Sandstone molasse
Sheet-pile walls
Excavation for permanent anchors
Investigation gallery
Compact molasse compacte
Horizontal beam
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Retaining structuresPermanent anchors
Tunnel face supportFiberglass bolts (GFK)
Superior horizontal beam
Pile walls
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
1. Initial state
Excavation fillingmodelized by triangular
shaped horizontal forces
Existing retaining structure
(constructed before filling)
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
2. Construction of the pile walls
Front and lateral pile walls
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
3. Permanent anchors in embankment
Excavation and anchors
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Anchors activatedstep by step
4. Step by step excavation
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
6. Demolition of piles in front of the tunnel crown Construction of the umbrella vault
Umbrella vaultLongitudinal steel tubes
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
8. Excavation of the tunnel upper half and activation of the initial support
Vue of the tunnel excavation
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Displacements
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Bending moments in piles and top beam
Horizontal cross section in beam
Vertical cross section in pile wall
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Tensile forces in bar anchors on the tunnel face
Tunnel face – GFK bolts
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Tunnel in marny molasse
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Tunnel cross section
14m94
R =
7m97
Arch supportSteel ribs HEB 240 and concrete filling
Umbrella vaultLongitudinal steel tubes
First drift (upper half)
Second drift (lower half)
Support of the invertSteel ribs HEB 240 and concrete filling
Support of the coreSteel ribs HEB 240 and concrete filling
Support of the coreRock bolts
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
30 m
18 m MarnyMolasse
ZSoil 2D Model
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Step 1
Initial state
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Arch supportBeam modelising the steel ribs and
concrete filling
Invert supportBeam modelising the steel ribs and
concrete filling
Umbrella vaultRadial bars modelizing the flexibility of the
longitudinal steel tubes
Base of arch supportVolumetric elements
Step 2
2a Activation of umbrella vault
2b Excavation of upper half
2c Arch and invert support
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Step 3
3a Transfer of the efforts from theumbrella vault to the arch support
3b Activation of rock bolts for coresupport
Removal of radial bars modelising theumbrella vault
Rock boltsTruss elements
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Step 4
4a Removal of first invert support
4b Excavation of lower half
4c Activation of core and final invertsupport
Core and invert supportBeam modelising the steel ribs and
concrete filling
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Step 5
5a Activation of tunnel lining
5b Transfer of efforts from initial support to lining
Tunnel liningContinuum for structures
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Problems with 2D model:
Unconfinement rate of upper half: well documented -> assumptions made in 2D ok
Unconfinement rate of core : not well documented - > specific 3D model
Stability of tunnel face - > specific 3D model
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
30 m
15x2 = 30 m
4 m
5x2 + 10x1 =
20 m
27 m
18 m
MarnyMolasse
Excavation of the core and invert by steps 2m long starting from the south
portal going north.
Excavation of thelower half
ZSoil 3D Model
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Support systems
Rock boltsConstructed from the first invert
Base of arch supportVolumetric elements
Core and invert supportsShell modelizing steel ribs and
concrete filling
Arch supportShell modelizing the steel ribs and
concrete filling
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
1. Excavation of upper half in one step 2. Activation of rock bolts
3. Removal of first invert and excavation oflower half by 2m long steps
Excavation steps
4. Activation of core and invert support following the excavation
5. End of excavation and activation ofinner lining
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Variable
4 m – 18 m
Arch and invert supportShell modelizing steel ribs and
concrete filling
Marny Molasse
30 m
3x2+10x1+4x2 = 24 m
3 models :
27.5 m, 34.5m
et 41.5 m
Umbrella vaultROR steel tubes
Face supportRock bolts
Tunnel face stabilityZSoil 3D Model
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
1. Initial state 2. Activation of the umbrella vault
3. Activation of face support 4. Step by step excavation and support of the upper half over the first 6 meters
5. Face stability (decrementation ofc molasse from Ck to Cd)
Excavation steps
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Displacements
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Tensile forces in tunnel face rock bolts
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Friction along tunnel face rock bolts
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Graitery Tunnel– Use of Zsoil for complex excavationsZsoil-Day 2009
Conclusion:
• Use of several models adapted to specific problems
• Start with basic model (elastic, no contact, single phase) then add complexity
• Start with small model, then extend to get correct boundary conditions
• Complex models can confirm results of specific models
• For retrofit analysis, complex models cannot be sparedbut when results correspond well to in-situ measurements, the reward is worth the effort
Faster model generationRefined mesh around studied areaFaster calculation allows for more case studies
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