Tunnel Support Composite Linings. W. Aldrian, BASF

Transcription

1 Tunnel Support Composite Linings W. Aldrian, BASF 1

2 Tunneling is known to be conservative! Is it really the case? 2011, UK 1951, Austria

3 Watertight Rock Support High ductility to absorb ground movement without failure Ductility Waterproofing Ensure dry tunnel for long durability, ease of maintenance and operational safety Repair capability Easy to repair with minimum interruption of operation and without affecting structural integrity Systems that withstand high temperatures and that allow water vapor transmission to prevent spalling Fire resistance Bonding Full load bearing capabilities and defined quality to serve as permanent rock support method Load bearing Sufficient bond in between layers to withstand de bonding from water pressure and to ensure load transfer

4 Ground support solutions TML 5 20 mm thin mortar lining with bearing load capacity and bending flexibility for initial rock support and anti weathering in strong fissured soft and hard rock Sprayed Concrete 5 8 cm / cm as temporary and / or permanent rock support, with AFA as tunnel lining where water ingress is not an issue TSL 3 10 mm thick flexible rock coatings for antiweathering or vent stopping in soft rock and swelling clays Composite Lining 3 5 mm thick flexible bonded water barrier with load transfer and crack bridging characteristics to enable composite shell linings of Permanent Sprayed Concrete SCL TML TSL CL load bearing capacity, mineral composite, brittleness, applied thickness ductility, organic composite, sealant properties 4

5 What is desired? 5

6 and what is not desirable! 6

7 Composite Lining Continuous structure with a bonded membrane Composite mechanical behaviour The tensile bonding and shear strengths of the concrete-membrane-concrete result in a mechanical behavior of a composite structure. The primary support lining and the inner final lining act together and can be considered as part of the permanent support structure. 7

8 The bond Concrete Membrane Identical bond on both sides Same for sprayed or cast concrete Fully encapsulates aggregates and crystals on the concrete surface 8

9 Composite Lining The SYSTEM 1. Spray application 2. System water tightness 3. Composite Lining 9

10 Equipment and preparation works 1. Spray application of membrane 10 10

11 Manual and mechanized application 1. Spray application of membrane Nordöy Road Tunnel, Faroe Islands

12 Complex geometries 1. Spray application of membrane Road Tunnel Portela, Portugal 12

13 Lining follows the uneven rock surface 1. Spray application 13 Nordöy Tunnel, Faroe Islands

14 No shutter works, both linings sprayed 1. Spray application 14 Station Puente Alto, Santiago de Chile

15 Sheet membrane - failure mechanism 2. System water tightness Sprayed concrete Geotextile fleece Sheet membrane Inner concrete lining 1st stage: Sheet formation 2nd stage: Application 15 15

16 Sprayed membrane - failure mechanism 2. System water tightness Sprayed concrete Sprayed membrane Inner concrete lining One stage: Sheet formation & application 16

17 Sprayed membrane - bonded! 2. System water tightness 1st lining Inner lining 17 17

18 Sprayed membrane - bonded! 2. System water tightness 18 18

19 Sprayed membrane - bonded! 2. System water tightness 19 19

20 Sprayed membrane - bonded! 2. System water tightness 20 20

21 Sprayed membrane SINGLE bonded only! 2. System water tightness.assuming in this case no bond to inner lining 1. Water travels at interface, sets whole compartment under water leakage not easy detectable 2. Water pressure acts on inner lining only! 21 21

22 Sprayed membrane double bonded! 2. System water tightness 1. One wet spot only this leakage is easy detectable 2. Water pressure acts on both linings! (thin inner linings possible!) 22 22

23 Design considerations 3. Composite Lining Primary Lining seen as temporary only Primary Lining seen as permanent TSCL Cast insitu Benefit from: - Bond - Easy placing of sprayed membrane & sprayed concrete inner lining Benefit from: - Bond - Easy placing of sprayed membrane & sprayed concrete - Reduced lining thickness through composite structure TSCL Cast insitu TSCL PSCL Benefit from: Bond and placing spray. membrane 23

24 Tests to evaluate parameters 3. Composite Lining 24

25 Shear bond strength 3. Composite Lining 25

26 System evaluation and analysis 3. Composite Lining Mott MacDonald Back-analysis of shear test data 280mm thick primary lining 3mm layer of Masterseal mm thick secondary lining 26

27 System evaluation and analysis 3. Composite Lining Conclusions There was no shear failure on the interface Even with 25% of the expected shear strength, successful load sharing occurs Single shell structure is possible with Masterseal 345 Performance is relatively insensitive to the precise strength or stiffness values 27

28 Proof of concept 3. Composite Lining Fiber reinforced sprayed concrete either side, 5 cm membrane 5cm Pure fiber reinforced sprayed concrete, 10 cm Load Load Deflection / mm 25 Deflection / mm 25

29 Long term evidence Examples Long term evidence Giswil Escape Tunnel, Switzerland 29

30 Long term evidence Examples Giswil Escape Tunnel, Switzerland 30

31 Long term evidence Examples Pressure varying, up to nearly 5 bar Tunnel perfectly dry Giswil Escape Tunnel, Switzerland 31

32 Versatility interface in-between systems Examples Collombey Road Tunnel, Switzerland Prague Metro, Czech Republic 32

33 Composite Lining Examples Tunnel Viret, Lausanne, Switzerland 33

34 Composite Lining Examples 34 Tunnel Viret, Lausanne Switzerland

35 1 2 3 Value engineering Example Hindhead Tunnel Two, fully detailed design solutions SFRS Primary lining 2. PVC sheet membrane 3. Plain cast in-situ concrete Secondary lining 1. SFRS Primary lining 2. Spray applied membrane 3. Sprayed concrete Secondary lining 4. Plain cast in-situ concrete walls Hindhead Tunnel, 2 x 1.8km, England 35

36 Primary Lining as permanent support Example Hindhead Tunnel 200mm sprayed concrete primary, permanent lining For durability, all steel elements designed out: Top heading No lattice girders No mesh No rock bolts Bench Steel / structural plastic fibre reinforced 36

37 Sprayed c. primary, permanent lining Example Hindhead Tunnel 37

38 Spray applied waterproofing membrane Example Hindhead Tunnel 38

39 Cross passages Example Hindhead Tunnel Cast in situ reinforced concrete Reinforcement was required around the Cross passage openings Rebar was drilled into the ground then sprayed over with Masterseal

40 Casting sidewalls Example Hindhead Tunnel 40

41 Completed tunnel Example Hindhead Tunnel 41

42 Refurbishment Examples Brajdica Rail Tunnel, Rijeka Croatia Dover Rail Tunnel, UK 42

43 Refurbishment Examples Chekka Highway Tunnel, Lebanon 43

44 Architectural options Examples Station Puento Alto, Santiago de Chile 44

45 Combined with cast concrete Examples Access tunnel to Station Florence, Prague Metro, Czech Republic 45

46 Value of Composite Linings Owners Reduced total construction time and costs Reduced maintenance and operational costs Reliable technical solution Designers Composite waterproof tunnel lining opens up new cost-effective design opportunities Composite behavior of entire lining allows for significant reduction of lining thicknesses Compatibility with other waterproofing systems allows for combination of two systems, and hence the possibility of better technical optimization Exceptionally cost-effective for rehabilitation of old tunnels Contractors Simple application methodology, highspeed application, effective use of labor Fiber reinforced sprayed concrete final lining can be easily applied onto membrane For short tunnels sprayed will be cheaper than buying expensive formwork For complex geometries such as tunnel junctions and widening's formwork is expensive and slow. Shotcrete casting quality can be checked visually during spraying unlike in-situ concrete Permanent works can proceed easily along with the excavation process- save time

47 Thank you for your attention 47