In This Article We Cover Various Shape Of Tunnels With Example.
Shape Of Tunnels Depend Upon Nature Of Soil, Pressure Of Ground And Purpose Of Tunnel.
Circular Section
It Offers Grater Resistance To External Pressure Caused By Water, Water Bearing Soils Or Soft Grounds.
It Is Best Theoretical Section For Resisting Internal Or External Forces, It Provides Greater Cross Section Area For Least Perimeter. Mostly Suitable For Sewers And Water Conveying.
Circular Section Tunnels Suited In Non-Cohesive Soils. And Suitable For Tunnels Driven By The Shield Method.
Disadvantages Of Circular Section
- Circular Tunnels Not Suitable For Roads Or Railways As More Filling Will Required For Flat Base.
- In Circular Tunnels Placement Of Concrete Lining Is Difficult.
D Section Or Segmental Roof Section
It Is Section With An Arched Roof With Straight Sides.
The Segmental-Roof Takes The External Load And Transfers On Vertical Side Walls, Which May Be Constructed Of R.C.C In Case Of Soft Soils.
D Shape Tunnels Suitable For Subway Or Navigational Tunnels, It Has Nearly Flat Invert And Additional Working Floor Space Helpful During Driving And Flat Floor Useful In Moving Equipment.
Egg Shaped Section
It Generally Adopted For Carrying Sewage, As It Provide Least Cross Section Area At Bottom.
In Egg Shaped Tunnels Self Cleansing Velocity Of Flow Of Sewage Maintains In Dry And Rainy Seasons.
It’s Circular Side Walls Resist External And Internal Pressure.
Elliptical Section
This Section Is Narrow At Base, So Cannot Be Used As Traffic Tunnels.
It’s Major Axis Is Kept Vertical To Have Better Resistance To External Pressure, Suited For Carrying Water And Sewage.
Horse Shoe Section
It Is Most Popular Section For Tunnels, Has Semi Circular Roof With Arches Sides And Curved Invert.
This Tunnels Suitable In Soft Rock.
Horse Shoe Section Tunnels Commonly Used For Highway And Railways, Also Suitable For Carrying Water And Sewage.
When Lined, Section Gives Good Resistance To External Pressure.
Floor Is Nearly Flat, Which Gives More Working Space To Contractor To Store Materials During Construction.
Horse Shoe Section Tunnels Difficult To Construct.
Rectangular Section
It Is In The Form Of RCC Box And Most Suitable Case Of Hard Rocks.
Generally Adopted For Pedestrian Traffic.
Rectangular Section Are Costly And Difficult To Construct.
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Author & Editor Of This Blog.
Founder Of “KPSTRUCTURES”
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