The stability of a layered mine roof reinforced with full-column grouted bolts has been theoretically examined. The shear forces Tr that must be resisted by the bedding planes so as to maintain all of the layers at a given roof sag is calculated. The influence of seam face advance and initial, horizontal stress on Tr has also been studied. The question of stability has been discussed qualitatively in terms of the shear forces required (Tr) and available to attain stability. It is shown that control of roof sag prior to bolt-installation is the key to success of any bolting system. Further, an attempt has been made to explain why resin grouted bolts perform more efficiently than mechanically anchored bolts in the field.

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