Correct Answer : Spring line
Explanation : Spring line is determined as the line at which the wall breaks from sloping outward to sloping inward toward the crown. This acts as a barrier between the outward and inward regions.
Correct Answer : Option (D) : 2N + 2
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.
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.
