If 'D' is the diameter of tunnel in meters, then the thickness of lining in mm, as per the empirical formula is given by

42 D

82 D

104 D

124 D

Correct Answer : 82 D

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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.