tuneles1
DESCRIPTION
tunelesTRANSCRIPT
![Page 1: tuneles1](https://reader034.vdocuments.mx/reader034/viewer/2022051402/5695d0171a28ab9b0290ee1f/html5/thumbnails/1.jpg)
04/22/23
Tunnels in Swelling and Squeezing Grounds
KYUHO CHO
BUMJOO KIM
![Page 2: tuneles1](https://reader034.vdocuments.mx/reader034/viewer/2022051402/5695d0171a28ab9b0290ee1f/html5/thumbnails/2.jpg)
04/22/23
Contents
Definition of Swelling and Squeezing Mechanisms
Empirical Values of Support for Case Tunnel (Highway)
Analytical Values of Support for Case Tunnel (Highway)
Design Values for the Support through the 2 methods
Excavation and Supports
Conclusion
![Page 3: tuneles1](https://reader034.vdocuments.mx/reader034/viewer/2022051402/5695d0171a28ab9b0290ee1f/html5/thumbnails/3.jpg)
04/22/23
Definition of Swelling and Squeezing Mechanisms
Swelling Mechanism: - A combination of physico-chemical reaction involving water and stress relief leading to volume increase with time
- Argillaceous soil or rock (Clay, Shale/Mudstone, Fault gouge, and Weathering/Alteration zone)
Squeezing Mechanism: - Time dependent shear displacement of the ground leading to inward movement of the tunnel periphery - Any soil or rocks as long as the ground around tunnel creep
![Page 4: tuneles1](https://reader034.vdocuments.mx/reader034/viewer/2022051402/5695d0171a28ab9b0290ee1f/html5/thumbnails/4.jpg)
04/22/23
Ground and Tunnel Parameters
Ground = shale (cretaceous), fault zone
qu = 10 Mpa
v = 0.8 Mpa (Z=40m, r=20 KN/m3)
E = 500 Mpa, = 0.4
Material constant for shale (Hoek-Brown)
m=0.2 & s=0.0001, mr=0.01 & s=0
Max.swelling pressure = 0.2 Mpa (Oedometer test)
Initial radius of tunnel = 7 m
De = 14/1.0 = 14
![Page 5: tuneles1](https://reader034.vdocuments.mx/reader034/viewer/2022051402/5695d0171a28ab9b0290ee1f/html5/thumbnails/5.jpg)
04/22/23
Plan & Cross-sectional Views of the Case Tunnel
![Page 6: tuneles1](https://reader034.vdocuments.mx/reader034/viewer/2022051402/5695d0171a28ab9b0290ee1f/html5/thumbnails/6.jpg)
04/22/23
Empirical Method (Q-system)
1. RQD = very poor (10)
2. Jn = 3 joint set + random (12)
3. Jr = smooth planar (1.0)
4. Ja = swelling clay (montmorillonite) filling (10)
5. Jw = medium inflow or pressure (0.66)
6. SRF = mild swelling/squeezing (8)
Q = (RQD/Jn)(Jr/Ja)(Jw/SRF)
= (10/12)(1.0/10)(0.66/8) = 0.007
Category 38 (Barton’s Design Category)
= CCA (sr) 100-300 cm + B (tg) 0.5-1.0 m
![Page 7: tuneles1](https://reader034.vdocuments.mx/reader034/viewer/2022051402/5695d0171a28ab9b0290ee1f/html5/thumbnails/7.jpg)
04/22/23
Design category by Q-system
![Page 8: tuneles1](https://reader034.vdocuments.mx/reader034/viewer/2022051402/5695d0171a28ab9b0290ee1f/html5/thumbnails/8.jpg)
04/22/23
Analytical Method(Rock-support interaction)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0 20 40 60 80 100
ui (mm)
pi
(Mp
a)
Steel rib Con'c lining Rockbolt Ground
![Page 9: tuneles1](https://reader034.vdocuments.mx/reader034/viewer/2022051402/5695d0171a28ab9b0290ee1f/html5/thumbnails/9.jpg)
04/22/23
Plot of Design Values by RQD
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0 20 40 60 80 100
ui (mm)
pi
(Mp
a)
Steel rib Con'c lining Rockbolt Ground
![Page 10: tuneles1](https://reader034.vdocuments.mx/reader034/viewer/2022051402/5695d0171a28ab9b0290ee1f/html5/thumbnails/10.jpg)
04/22/23
Plot of Design Values by Q-system
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0 20 40 60 80 100
ui (mm)
pi
(Mp
a)
Con'c lining Rockbolt Ground
![Page 11: tuneles1](https://reader034.vdocuments.mx/reader034/viewer/2022051402/5695d0171a28ab9b0290ee1f/html5/thumbnails/11.jpg)
04/22/23
Comparison of Empirical & Analytical Method
Empirical values
By RQD
- rock bolt : 0.6-0.9m spacing
- shotcrete : > 0.15m - steel rib (very heavy) : 0.6m spacing
By Q-system - Cast concrete arch : 1-3m - rock bolt (tensioned grouted) : 0.5-1.0 m spacing
More conservative Safer Design
Analytical values
- rock bolt (mechanically
or chemically anchored)
: 0.5m spacing
: 3m length
- concrete lining : 0.3m
- steel rib : 0.3m
: 12W65
More accurate
More Limitation
![Page 12: tuneles1](https://reader034.vdocuments.mx/reader034/viewer/2022051402/5695d0171a28ab9b0290ee1f/html5/thumbnails/12.jpg)
04/22/23
Excavation and Support
Excavation Methods
Sequential excavation
- Side drift method
- Heading and bench
Full face excavation
![Page 13: tuneles1](https://reader034.vdocuments.mx/reader034/viewer/2022051402/5695d0171a28ab9b0290ee1f/html5/thumbnails/13.jpg)
04/22/23
Side drift method
Heading and Bench
Full face excavation
Spring line side drift method
![Page 14: tuneles1](https://reader034.vdocuments.mx/reader034/viewer/2022051402/5695d0171a28ab9b0290ee1f/html5/thumbnails/14.jpg)
04/22/23
Excavation and Support
Effect of different support measures
Side drift method Heading and Bench
![Page 15: tuneles1](https://reader034.vdocuments.mx/reader034/viewer/2022051402/5695d0171a28ab9b0290ee1f/html5/thumbnails/15.jpg)
04/22/23
Additional Considerations on Supports in Tunnels in Squeezing Condition
Non-uniform distribution of the ground pressure
Main causes for the deviation of deformations from rotary symmetrical state
![Page 16: tuneles1](https://reader034.vdocuments.mx/reader034/viewer/2022051402/5695d0171a28ab9b0290ee1f/html5/thumbnails/16.jpg)
04/22/23
Additional Consideration on Supports in Tunnels in Squeezing Condition
Response of Supports to Non-uniform Distribution of Ground Pressure
![Page 17: tuneles1](https://reader034.vdocuments.mx/reader034/viewer/2022051402/5695d0171a28ab9b0290ee1f/html5/thumbnails/17.jpg)
04/22/23
Conclusion
We made a comparative study on the supports of the case tunnel in time-dependant ground(Shale) with the rock-support interaction analysis and empirical methods (RQD and Q-system).
The design values by rock-support interaction and Q-system showed the satisfactory results with respect to the ground stability than RQD for the given tunnel.
It is not easy to predict how much the swelling and squeezing occur with time at the stage of design.
Most important is the integration of design and construction including monitoring during construction and the possibility to adapt the design, if necessary.