What determines the need for secondary support in underground mines?
A. Support material quality
B. Lighting arrangement
C. Primary support effectiveness
D. Air velocity
Answer: Option C
Solution (By Examveda Team)
Secondary support supplements primary systems when they are insufficient.The correct answer is: Primary support effectivenessFactors like convergence or new cracks may trigger need.Includes cable bolts, retimbering, etc.This Question Belongs to Mining Engineering >> Mine Development And Mining Methods
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