Download - Structural design of tunnel lining
![Page 1: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/1.jpg)
STRUCTURAL DESIGN OF
TUNNEL LINING
PRESENTED BY:
Mahesh Raj Bhatt
M.E. In Structural Engineering
Kathmandu University31th march-2017
![Page 2: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/2.jpg)
Content outline:
Team work in tunnel design
Fundamental approach of design
Lining in tunnel
Mode of failure in lining
Design of lining
Initial design
Final design
Conclusion
![Page 3: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/3.jpg)
Team work in tunnel design:
i. Engineering Geologist: geo-exploration
ii. Hydraulics engineer: tunnel pressure, profile
iii. Structural engineer: lining type and material selection
iv. Geotechnical engineer: ground support requirement
v. Civil engineer: construction, location, layout
vi. Surveyor: maps, geometric frameworks
vii. Environmentalist: Environmental issues
viii.Construction engineer: construction issue
ix. Other experts: estimation, costing, quality expert etc.
![Page 4: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/4.jpg)
Fundamental approach of design:
• Engineers promise that the structure will neither suffer structurally nor collapse during its projected lifetime.
• Design must be
• Safe
• Stable
• functional
• Possible failure modes should be analyzed.
![Page 5: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/5.jpg)
Lining in tunneling:
Steps in structural design construction
• Excavation: Blasting / mechanical tools
• Initial ground support: safety during work
• Final ground support: structural safety
what is tunnel lining?
• timber, brick, concrete, or steel supports erected in a tunnel to maintain dimensions and safe working conditions.
• And finally for permanent safety of the system.
![Page 6: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/6.jpg)
Mode of failure in tunnel
Can be categorized
i. Failure due to discontinuity: fault, joint, fold
ii. due to stratified rocks
iii. Rock fail by stress: squeezing, in fault zone, weak and expansive soil in deeper zone.
iv. Fail by mineral control
v. Water pressure control: swalling
vi. Seismic effects
vii. Other permanent soil land displacement
viii. Failure in shortcrete
ix. Failure in rock bolt and dowel system etc.
![Page 7: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/7.jpg)
Fig: tunneling in Rock stratification:
![Page 8: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/8.jpg)
![Page 9: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/9.jpg)
![Page 10: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/10.jpg)
![Page 11: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/11.jpg)
Design of lining
Types:
a) Design of initial support
installed after excavation to support the opening safely.
b) Design of final lining:
to make the structural safety and stability
![Page 12: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/12.jpg)
a) Design of initial support:Based upon: how to select material for support
i. empirical method: Terzaghi (1946)
ii.Theoritical method/ analysis method
iii.Fundamental approach: based on potential failure mode
i) Imperical method: (design of steel ribs)
-based on the experience
-terzagi (1946) gave written rule for selection based on Rock loads and RQD-index of the rock.
(RQD=rock quality designation)=degree of joint in rock mass
![Page 13: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/13.jpg)
•Skinner , Wickman, Tiedeman (1972)
• Gave Rock structure rating (RSR)
Rock type
Joint
Discontinuity
Fault
Fold
Orientation based
![Page 14: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/14.jpg)
![Page 15: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/15.jpg)
![Page 16: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/16.jpg)
ii) Theoretical method:
It deals with design of
• rock bolts
•Dowels
•Shortcrete
•Steel ribs design
•Rock bolts: based on 3-D wedge analysis
•Shortcrete: to make immediate stiffness to excavated rocks
•Dowel: to support mass / and reduce deflection
![Page 17: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/17.jpg)
![Page 18: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/18.jpg)
Design of steel ribs:
• Bent I-section or H-section made circular (steel)
Ribs are oriented to act as arch action which reduces moment in the section.
![Page 19: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/19.jpg)
b) Design of final lining:
• Common options are:
•Un reinforced concrete
•Reinforced concrete
•Segmental concrete
•Steel backfill with concrete
•Concrete pipe with backfill
•Steel backfill with grout
Note: interaction between rock and lining material is important to design the lining in tunneling.
![Page 20: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/20.jpg)
• Unlined tunnel: water excess to rock
• Shot-crete: to provide ground support, hydraulics
• Un reinforced line : to protect rock exposure, smoothen
• Reinforced line:
1-layer:temperature stress and shrinkage
Multi layer: swelling, squeezing, high stress
• Steel lining: when internal pressure > external pressure/
ground or ground water
![Page 21: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/21.jpg)
![Page 22: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/22.jpg)
![Page 23: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/23.jpg)
Load cases for design:
![Page 24: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/24.jpg)
Design requirements:
• Lining thickness: tmin>300 mm
Min cover>100mm
Guideline EM-1110-2-2104 for concrete cover
• concrete mix design:
•Most cases=M21 (21 mpa)
•Thin line =M35
•Segmental line=M42
•Reinforcement: 0.28% of X-section of line
0.4% for blast type tunneling
note: reinforce for crack control due to temperature/pressure etc.
![Page 25: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/25.jpg)
Lining for external water pressure:
• If P external water< P internal water
Than take
P ex=Pin ( because leakage increases
external pressure)
•if Tlining< R/10 (R-radius of tunnel)
![Page 26: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/26.jpg)
•If T lining>R/10
![Page 27: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/27.jpg)
Circular tunnel with internal pressure:
Concerns are mainly on
1)Rock lining interaction
2) estimation of lining leakage
1) Rock lining interaction
-thin shell equation ( radial displacement of lining)
-cylinder theory for thick lining
![Page 28: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/28.jpg)
To find radial displacement of lining:
![Page 29: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/29.jpg)
2) Lining leakage estimation:
![Page 30: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/30.jpg)
Lining for bending and distortion:
![Page 31: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/31.jpg)
Note: moment and forces analysis must be done using Finite element analysis tools
![Page 32: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/32.jpg)
![Page 33: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/33.jpg)
Design of steel liners:
• Amstutz (1970)
• Jacobson(1974)
• Vaughan (1956)
• Moore (1960) computer solution:
•To find the critical buckling pressure .
![Page 34: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/34.jpg)
![Page 35: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/35.jpg)
Linear ring lining design: basic approach
• A liner ring is statically indeterminate.
• A one pass lining is designed for transport and erectionloads, loads during grouting, and ground loads
• For a circular ring of constant cross section
symmetrically loaded
the thrust at the crown C is
![Page 36: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/36.jpg)
![Page 37: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/37.jpg)
![Page 38: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/38.jpg)
![Page 39: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/39.jpg)
• Note: in ring segmental design all the analysis procedure is same as like as parabolic/circular arch.
• Based upon the fined analysis result rebar must be designed .
(horizontal thrust/ shear / and moment are governing parameters for the lining rebar design)
![Page 40: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/40.jpg)
CONCLUSIONS:
• Lining design should be safe , stable andfunctional
• Lining type depend upon the property of theinterior rock or soil.
• To save the rock portion to be exposure, lining isdone.
• To give additional support to rock mass lining isneeded.
• There are various methods for lining design thesemay be not structural sometime these may beonly based upon the constructional approach.
![Page 41: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/41.jpg)
Thank you!!
THANK YOU!!
Tunnel spillway in Kanogawa dam Japan
![Page 42: Structural design of tunnel lining](https://reader034.vdocuments.us/reader034/viewer/2022050706/5a6624e47f8b9ad5138b4a73/html5/thumbnails/42.jpg)
References:
• Engineering and design tunnel and shaft in rock, CECW-EG
Engineer Manual1110-2-2901 Department of the Army U.S. Army
Corps of Engineers Washington, DC 20314-1000
• TUNNEL ENGINEERING, 20 Lars Christian F. Ingerslev , Arthur
G. Bendelius Parsons Brinckerhoff New York, New York
• PRACTICAL TUNNEL, CONSTRUCTION Gary B. Hemphill PhD,
PE, JOHN WILEY & SONS, INC.