In This Article We Covers What Is Tunnel ? And Classification Of Tunnels Briefly With Examples.

What Is Tunnel?

A Tunnel Is Define As An Underground Passage For The Transport Of Passengers, Water, Sewage, Minerals, Gas Etc.

Tunnels Are Economical For Grater Depth As Compared To Open Cuts. (Open Cuts?)

Classification Of Tunnels

Tunnels Classified On The Basis Of Purpose, Shape, Alignment, Materials, And Supporting Arrangements.

1) Classification Of Tunnels According To Alignment:-

A) Spiral Tunnels:-

Spiral Tunnel Provided To Increase The Length Of The Tunnel To Avoid Steep Slops In Narrow Valleys.

Tunnels Provided In Narrow Valley In The Form Of Loops In The Interior Of Mountain So As To Increase Length Of Tunnel To Avoid Steep Slopes.

Classification Of Tunnel-Spiral Tunnel
Classification Of Tunnel-Spiral Tunnel

B) Off-Spur Tunnels:-

Off Spur Tunnels Are Constructed To Short-Cut Minor Obstacles Is Very High Projections On The Way, Which Can Not Be Followed With Permitted Curves.

Classification Of Tunnel-Off Spur Tunnel

C) Saddle Tunnels:-

Saddle Tunnels Constructed In Valley Along Natural Slope, This Tunnels Mainly Used For Transportation Purpose. Or Tunnels Constructed In The Valley Along The Natural Slope Till Slope Does Not Exceed Ruling Gradient.

Classification Of Tunnel-Saddle Tunnel

D) Slope Tunnels:-

Tunnel Constructed In Steep Hills For Economic And Safe Operations Of Roads And Railways Non As Sloping Tunnels, This Type Of Tunnel Also Used For Transportation Purpose Mainly.

Classification Of Tunnel-Slope Tunnel

2) Classification Of Tunnel According To Purpose

A) Conveyance Tunnels:-

These Type Of Tunnels Mainly Constructed For Water Supply, Sewage Lines, And Hydro-Electric Power Supply.

Classification Of Tunnel-Conveyance Tunnel

B) Traffic Tunnels:-

Traffic Tunnel Includes Highway Tunnels, Railways Tunnels, Pedestrian, Navigation Tunnels And Subway Tunnels.

Classification Of Tunnel-Traffic Tunnel

3) Classification Of Tunnels According To Shape

A) Circular Shaped Tunnels:-

This Type Of Tunnels Strong In Order To Resistance To External Pressure Caused By Water, Soil and Ground.

Circular Shape Tunnels Not Suitable For Railways, And Highway Transportation Mainly Used For Sewage Lines.

Classification Of Tunnel-Circular Shaped Tunnel

B) Horse Shoe Tunnels:-

Horse Shoe Tunnels Can With Stand Internal And External Pressures, Having Semi-Circular Rood With arch Sides, Commonly Uses For Railway And Roadways.

Classification Of Tunnel-Horse Shoe Tunnel

C) D-Shaped Tunnels:-

Where The Risk Of Failure Or Collapse Caused By External Pressure From Water Or Loose Unstable Soil Conditions On Tunnel Lining Is Non-Existent, These Types Of Tunnel Roof Also Called Segmented Roof Takes Up All The Load And Distributes It To The Straight Walls.

Classification Of Tunnel-D Shaped Tunnel

D) Elliptical Tunnels:-

The Smaller Cross Section At The Bottom Maintain Flow At The Required Self Cleaning Velocity, They Used In Grounds Compare To Rocks And These Tunnels Serve As Water Sewage Conditions.

Elliptical Tunnels Difficult To Construct.

Classification Of Tunnel-Elliptical Shaped Tunnel

E) Rectangular Tunnels:-

Rectangular Tunnels Suitable For Hard Rock Sites And Mainly Uses For Pedestrian Passage, But This Type Of Tunnels Are Costly.

Classification Of Tunnel-Rectangular Shaped Tunnel

F) Egg-Shaped Tunnels:-

Egg Shaped Tunnels Suitable For Sewage Lines As They Have Self Cleaning Velocity In Dry Weather, Egg Shaped Tunnels Can Resist External As Well As Internal Pressure.

Classification Of Tunnel-Egg Shaped Tunnel

4) Classification Of Tunnels According To Type Of Materials

A) Tunnels In Hard Rock:-

Tunneling Through Hard Rock Almost Always Involves Blasting.

Tunneling In Hard Rock

B) Tunnels In Soft Ground:-

A Tunnel Built In Soft Ground Such As Clay, Silt, Sand, Gravel, Or Mud Requires Specialized Techniques Compared To Hard Rock.

Tunneling In Soft Ground

C) Tunnels In Open Cuts:-

A Tunnel Constructed By Excavating A Trench From The Surface, Building The Structure Within The Trench, And Then Backfilling To Restore The Surface.

Tunnels In Open Cuts

D) Tunnels Underneath River Bed:-

Tunnel Constructed Under River Bed Required Special Technique’s.

Tunnel Underneath River Bed

5) Classification Of Tunnels According To Supporting Arrangements

  • Tunnels Supported By Rock Bolts
  • Tunnels Supported By R. S. J Section
  • Tunnel Supported By Shotcrete
Classification Of Tunnels On Supporting Arrangement

Thank You For Visiting. (Allow Notification For Further Updates)


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