Question: A caving operation is conducted in a relatively weak rock mass where the joint persistence is 88%. Laboratory testing of intact core shows that Co

A caving operation is conducted in a relatively weak rock mass where the joint persistence is 88%. Laboratory testing of intact core shows that Co = 12,750 psi, and φ = 29◦. Specific weight of rock is 157 pcf. Joint cohesion is 75 psi and joint friction angle is 20◦. Depth of the undercut is 3,750 ft. Development drifts are 13 ft wide by 18 ft high. Loading is expected to increase 100% after caving has reached the surface. If the rock mass is not self-supporting with a safety factor of 1.5, then steel sets will be used, possibly in conjunction with rock bolts and shotcrete. Determine a combination support system that will provide a safety factor of 1.5 in any steel support and other reinforcement.

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Given Caving operation joint persistence is 88 Units convert for 20 Co12750 psi 29 y 157 pcf depth 3... View full answer

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