Tunnel definition in hindi
Tunnel (surang) ek underground raasta hai, jise aasapaas ki mitti / prthvi / chattaan se khoda gaya hai aur pravesh, nikaas ke alaava har jagah se band kar diya gaya hai.
Surang ko naram mitti se kathor chattaan tak alag alag prakaar ke materials mein khoda jaata hai. Surang nirmaan ki vidhi nirbhar karti hai-
- the ground conditions (jameen ki sthiti)
- the groundwater conditions (bhoojal kee sthiti)
- the length and diameter of the tunnel drive (surang drive ki lambayi aur vyaas)
- the depth of the tunnel (surang kee gahrayi)
- the logistics of supporting the tunnel excavation (surang khudayi ka samarthan karane ki rasad)
- the final use (antim upayog)
- the shape of the tunnel (surang ka aakaar)
- appropriate risk management (uchit jokhim prabandhan)
The branch of Civil Engineering which deals with the design, construction and maintenance of tunnels is known as Tunnel Engineering.
Shapes and its suitability
- Shapes – Suitability
- Circular section – Carrying water/non cohesive soil
- Horse shoe Section – Soft rock
- Egg shaped – Sewers/self cleansing velocity
- Segmental roof section – Subways
Construction methods and its advantages
- Construction method
- Full face method
- Heading and benching method
- Drift method
- Compressed air method
- American method
- Tunneling is continuous
- Simultaneous drilling & mucking is possible
- Helps in ventilation of tunnel
- Useful in soft & water bearing soil / not suitable in rocks
- For tunneling of large cross section area through soft ground driving a top drift and then widening the sides
Some important points on this:
a) Sequence of of operations in tunnel construction
- Placing steel
- Placing concrete
b) Cutting edge is a component of a shield for tunneling.
c) Alignment is carried out by Triangulation.
d) With the reference to tunneling, following factors are to be consider for deciding the size of shaft
- System used for hoisting
- Size of the muck car
- Quantity of muck to be lifted
- Eventual use of shaft
e) Combination of ‘Blow in’ and ‘Blow out’ methods is generally considered the best for its ventilation.
f) If the strata is sub-aqueous, Shield Tunneling method is employed.
g) Weisbach Triangle method is used to connect surface and underground tunnel surveys.
h) Additional access, quick removal of muck and natural ventilation in long tunnels be achieved by providing adits and shafts.
i) Needle beam method is adopted for tunneling in soft soils.
j) 0.2% is the minimum possible grade that can be provided in a it. And its approaches with providing proper drainage.