Which one of the following statements is not correct with regard to heading and hench-ing method of tunnelling.

Civil Engineering : Tunneling - Quiz(MCQ)

Driving of tunnel is done in two portions of its section

Driving the top portion is done in advance of the bottom portion

Firing of head holes is done just before the bench holes are fired

After driving the top portion 3 m to 3.5 m holes are drilled into the head and bench

Correct Answer : Firing of head holes is done just before the bench holes are fired

Recently Updated in Tunneling Questions

If 'N' is the number of shafts used, then the total number of faces available for attacking the excavation and construction in tunnels are

N + 2

2N + 1

2N + 2

Correct Answer : Option (D) : 2N + 2

Which of the following can act as an alternative for blasting?

Fire-setting

Tunneling

Continuous blasting

Sequential blasting

Correct Answer : Option (A) : Fire-setting

Explanation : Blasting is the conventional method which is adopted in case of rock tunneling. In the case of fire-setting, tunnel is heated with fire and then cooled with water. Rapid expansion and contraction weakens and rock and tends to break.

Which of the following involves in the sequence of rocky strata?

Placing rocks

Recording values

Marking profile

Improving foul gases

Correct Answer : Option (C) : Marking profile

Explanation : Rocky strata involve usage of blasting method for developing tunnels. The sequence contains marking profile, loading explosive, removing foul gases, checking, scaling, mucking and bolting.