tunneling

Question 1

ppt of tunneling

Answer 1

https://www.slideshare.net/RajatYadav18/tunnelling-methods-71012559

Question 2

needle beam method

Answer 2

Advantages:

i. suitable for soils where roof can stand for few minutes
ii. economical
iii. This method works all right on brick lining.

Disadvantages:

i. Heavy beam has to be pushed forward by hand.
ii. No of trench jacks required are large and they interfere with the efficient working of the gang
iii. Use of beams and bracing gives difficulties in mechanical methods of concrete lining.

Question 3

army method of tunneling

Answer 3

• mainly used for laying underground sewage
• simple and economic, uses only few timber planks with a trench jack or two
• limited usability due to small cross section

Question 4

american method

Answer 4

top drift first and then side drift

top arch supported by side plates

Question 5

English method

Answer 5

• This method is similar to the American method except that the roof load is supported by underpinning instead of using vertical posts.
• A drift is driven into the top of the tunnel about 5 m ahead of the existing arch lining. The drift is subsequently widened
• on both sides and supported by crown bars and posts. The work is carried on till the springing level is reached.
• The sill is then extended across the tunnel and the extended piece is supported by underpinning.
• This method requires good quality timber as well as simultaneous and frequent shifting from place to place.

Question 6

geological fold , fault and joints

Answer 6

https://www.slideshare.net/Vyankyo/structural-features-fold-fault-joints

FOLD: Permanent wavelike deformation in layered rock or sediment.

FAULT: A fracture in bedrock along which rocks on one side have moved relative to the other side.

JOINT: A fracture on a rock without noticeable movement.