Abstract: A method for providing secondary roof support in an underground mine such as to reduce the hazard of localized crumbling or deterioration of a mine roof. The apparatus generally comprises a slightly convex steel plate, crafted to cradle a roof bolt and which is supported by the base plate of the primary roof control system. The apparatus is utilized with standard primary roof bolt systems. By applying an upward pressure on the roof and effecting a larger coverage area for each roof bolt, the opportunity for drawrock separation to begin is reduced, and the exposure of the elements to drawrock strata in the vicinity of the bolt is eliminated. The method includes the step of utilizing the apparatus, with convex portion of the lateral plate facing upwards, before the placement of the base plate and roof bolt.

Abstract: A method and apparatus of re-tightening or retensioning a roof bolt in an underground mine serves the purpose of enabling the operator to place tension between the head of a permanent, epoxy-secured, roof bolt and the roof plate of a standard roof bolt system used to effect primary roof support in an underground mine. The method and apparatus have particular utility in mines in which drawrock or localized crumbling of shale of soft rock material is encountered as the first layer of material in the mine roof. The apparatus consists of a slotted screw member and slotted nut combination. A second embodiment of the apparatus is comprised of a slotted nut, slotted screw member, and one or more slotted spacers to be oriented between the roof bolt head and base plate. The members are turned with the appropriate tightening tool such as to apply pressure between the base plate and roof bolt head, thereby re-tensioning the roof bolt.