A 2.5m thick horizontal orebody is located at a depth of 80m, with the rock cover having a unit weight of 25kN/m3. An initial mining layout is based on 6m room spans and 5.0 m x 5.0 m pillars, with full orebody thickness of 2.5m being mined.
If Pillar strength = Sp = 7.18h-0.66 Wp0.46 Sp is in MPa, h & Wp in m. Comment on the design