The RMR (Rock Mass Rating) systemExplore further
2015-2-13u2002·u2002Locally bolts in crown, 3 m long, spaced 2.5 m with occasional wire mesh : 50 mm in crown where required . None : 3. Fair rock . RMR: 41-60 : Top heading and bench: 1.5-3 m advance in top heading; Commence support after each blast; Commence support 10 m from face . Systematic bolts 4 m long, spaced 1.5-2 m in crown and walls with wire mesh in crown
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