Caving Operation Is Conducted In Relatively Joint Persistenc

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 = 87.9 MPa, and φ = 29◦. Specific weight of rock is 24.8kN/m3. Joint cohesion is 517 kPa and joint friction angle is 20◦. Depth of the undercut is 1,143 m. Development drifts are 4mwide by 5.5mhigh. 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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