In vertical shaft sinking, what is a "collar"?
A. Explosive charge container
B. Opening of the shaft at surface
C. Roof bolt anchor
D. Bottom of the shaft
Answer: Option B
Solution (By Examveda Team)
Collar is the surface opening of a vertical shaft.The correct answer is: Opening of the shaft at surfaceIt requires strong reinforcement to prevent collapse and erosion.Usually supported by concrete or steel structures.This Question Belongs to Mining Engineering >> Mine Development And Mining Methods
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