1. The document discusses various terminology used for underground structures related to excavation such as adits, tunnels, shafts, chambers, and portals.
2. It also discusses tunnel construction methods like shield tunneling and cut-and-cover tunneling as well as tunnel boring machines (TBMs).
3. Key challenges with underground excavations discussed include rock falls, rock bursts, squeezing ground, and ensuring long-term stability, especially in challenging ground conditions.
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TERMINOLOGY FOR UNDERGROUND EXCAVATIONS
1. EXCAVATION OF
Author: Partha Das sharma, (B.Tech – Hons., in Mining Engineering)
E.mail: sharmapd1@gmail.com, Website: http://miningandblasting.wordpress.com/
2. TERMINOLOGY for UNDERGROUND
STRUCTURES
Adit
Tunnel
Subway
Shaft
Chamber
Portal
Pilot adit
Centre
Face
Wall ~ site
Floor
Roof
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4. Jet grouted roof cover
Shotcrete initial lining
Jet grouted floor cover
Top heading
Invert
Bench
Final concrete lining
SHIELD tunnelling method
CUT & COVER tunnelling method
TBM (Full face ~ Total Boring Machine)
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5. TERMINOLOGY for EXCAVATIONS of
ROCKS & SOILS
DRILLING
Hardness
Toughness
Abrasiveness
Structure
Drilkling fluids
AUGERING
MACHINE BORING
Total Boring Machine (TBM)
Full face excavation
BLASTING
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6. SCRAPING
RIPPING
DIGGING
GROUND WATER
Control of groundwater
Groundwater flow
Rate of flow
Volume of flow
Boundaries
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7. TUNNEL DESCRIPTION
1. Made into natural material (rocks)
2. Empty inside
3. Carry the loads itself
4. Both ends are open to atmosphere
5. Generally horizontal
6. Thick walled structure looks like cylinder
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9. 1- Key stone
2- Arch
3- Wall
4- Floor
5- Bench
6- Bench line or plane
7- Top heading
8- Invert
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10. Tunnel Section for Swelling Ground
1- Digging section
2- Support
3- Swelling section
4- Pressurized area
5- Flow direction of water
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12. UNDERGROUND EXCAVATIONS
In Rock
In Sediment
Stability & Arching
Water
Dry tunnel...............above water table
Wet tunnel..............below water table
Gases
Carbon dioxide (CO2)
Carbon monoxide (CO)
Methane (CH4)
Hydrogen sulphide (H2S)
Other gases
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13. Gas bursts
Rock falls
Rock bursts
Squeezing ground
Temperature
Subsidence
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14. EXPLORATION & INVESTIGATIONS
RELATED of SLOPE STABILITY
Geomorphologic maping and preparation of
longitudinal & cross sections
Geological maping & surveyings (aerial
photographs)
Geophysical surveyings
Underground explorations, boreholes
Ground water surveyings
Laboratory tests
Model studies
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16. SUBSURFACE EXCAVATIONS
1. GEOLOGY
a. Soil profile or hard rock geology
b. Structure
c. Ground water (hydrogeology)
d. Stability
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17. 2. INVESTIGATIONS
a. Mapping (Topographic, geologic, etc...)
b. Geophysical surveying (especially seismic
velocity of rocks)
c. Trial pits & boreholes
d. General and local stability analysis
e. Decide to excavation method
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19. UNDERGROUND EXCAVATIONS
Adit, shaft, incline, large chamber
Tunnel
Subway ~ metro
Underpass
Shelter
Power house
Ware house, store, mining ...etc
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20. GASES
(can be lethal or burst)
Carbon monoxide (CO) 0.97 of air
Carbon dioxide (CO2) 1.53 of air
Methane (CH4) 0.55 of air
(Highly explosive with air) marsh gas
Hydrogene sulphide (H2S) 1.19 of air
(Highly toxic and explosive)
Sulphur dioxide (SO2)
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21. ROCK FALL
SQUEEZING GROUND (sand, silt, shale, clay)
ROCK BURST
BULKING (Increase in volume, 10-40%)
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22. FACTORS EFFECTING
EXCAVATION of ROCKS
Mineralogical composition of rocks
Texture & fabric
Petrographic features
Structure
Rock mass
Strike & dip of beds in relation to face of
excavation
Intensity of tectonic disturbances
Degreee of weathering
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23. RESISTANCE of ROCKS to EXCAVATION
Loose soils
Soil easy to spade
Soil easy to dig
Crumbling weak rocks
Rocks easy to blast
Rocks difficult to blast
Rocks very difficult to blast
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25. SHIELD TUNNELLING METHOD
This method involves the use of shield machine to
drive the tunnels below the ground.
After completion of a work shaft, the shield machine
is lowered into the shaft and assembled there before
excavation and construction of the tunnels using
precast concrete lining segments of about 1.2 meter
width.
This construction method causes minimal disruption
to traffic and the environment because all the work
takes place below ground and the ground level
environment is unaffected.
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27. CUT and COVER TUNNELLING METHOD
This construction method, whereby the site is fully
excavated, the structure built and then covered over,
uses diaphragm walls as temporary retaining walls
within the site area.
Step one :Construction of diaphragm walls, pin piles,
and decking.
Step two :Excavation within the diaphragm walls,
installing struts as work progresses.
Step three :Construction of permanent floor slabs and
walls.
Step four : Fitting out the internal structures,
backfilling, and reinstating the surface structures.
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30. 1- Mechanical Support TBM
A mechanical-support TBM has a full-face
cutterhead which provides face support by
constantly pushing the excavated material
ahead of the cutterhead against the
surrounding ground.
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31. 2- Compressed-Air TBM
A compressed-air TBM can have either a full-
face cutterhead or excavating arms.
Confinement is achieved by pressurizing the
air in the cutter chamber.
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32. 3- Slurry Shield TBM
A slurry shield TBM has a full-face
cutterhead. Confinement is achieved by
pressurizing boring fluid inside the cutterhead
chamber.
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33. 4- Earth Pressure Balance Machine
An earth pressure balance machine has a
full-face cutterhead. Confinement is achieved
by pressurizing the excavated material in the
cutterhead chamber.
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34. 5- Mix-Face Shield TBM
Mix-face shield TBMs have full-face
cutterheads and can work inclosed or open
mode and with different confinement
techniques.
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35. EFFECT of GEOLOGICAL STRUCTURES
to TUNNEL EXCAVATION
Effect of soil layers: horizontal, vertical and
inclined layers have different kinds of loading
conditions for tunnels.
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36. Effect of faults: the relation between the fault
slope direction and the tunnel direction, width of
the fault zone, type and thickness of the fill
material and the hydrostatic pressures in both
sides of the fault are some problems in the
tunnelling.
Relation between the fault zone and the tunnel
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37. Tunnel excavations in the slopes: the
discontinuities (layers, fissures) inclined inside or
outside of the slope are very important regarding the
stress and strength of the tunnel.
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38. Effect of the folds: While tunnel is excavated in an
area that contains folded rocks, different stresses and
conditions may occur depending on the fold type.
Fold axis and the tunnel direction is parallel
Fold axis and the tunnel direction is vertical
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40. Classification of rocks for engineering
purposes is needed in analyzing the project
costs and to obtain an economic and reliable
solution.
The classification of the rocks, that the tunnel
will be constructed in, is first done by
Terzaghi. But, it is too general and gives
qualitative results.
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41. Rock classification and determination of unsupported span
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42. ONE of the LONGEST IRRIGATION TUNNELS in
the WORLD
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43. Consist of two concrete lined tunnels
each of which is 7.62 m in diameter and
26.4 km in length discharging water from
the reservoir of Atatürk Dam.
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