Abstract: An off-center rock bolt anchor includes a wedge nut having a modified frusto-conical lower end portion having a first surface portion with an enlarged radius of curvature matching that of the mine roof bolt hole. A threaded hole for receiving the shaft of a roof bolt extends longitudinally through the wedge nut parallel to and close to the first surface. A locking cam with outwardly oriented teeth is pivotally connected to an off-center portion of the top surface of the wedge nut. A plurality of expansion wings are positioned around the lower conical portion of the wedge nut and expand outwardly to engage the walls of the bolt hole as the wedge nut is tightened onto the roof bolt. Initial rotation of the bolt causes eccentric rotation of the wedge nut that urges the teeth of the locking cam to engage the side of the bolt hole.

Abstract: A mine roof bolt hole seal characterized by an arrangement of components which seal the bolt hole from the mine atmosphere at the time the roof bolt is installed and which, thereafter, provides for the removal of moisture and excess oxygen from within the bolt hole, through use of a desiccant and an oxidant. In the preferred invention form, the desiccant and the oxidant are automatically exposed during installation of the roof bolt.

Abstract: An improved method and mine roof bolt assembly for sealing a roof bolt hole in a mine to reliably prevent ambient mine air from entering the roof bolt hole. The roof bolt assembly includes a support plate, a roof bolt extending through a hole in the support plate, a flexible washer/gasket for providing a reliable seal between the support plate and a portion of the mine roof surrounding the roof bolt hole and also providing a reliable seal to the roof bolt shaft. An expansion shell is attached to a threaded end of the mine roof bolt to anchor the mine roof bolt assembly in the roof bolt hole. The washer/gasket includes an outer annular portion for providing a reliable seal between the mine roof and the support plate. The washer/gasket also includes a flexible inner annular portion for providing a reliable seal to the roof bolt shaft. The inner annular portion includes a relatively thin sphincter annulus which grips the roof bolt shaft to produce the seal therewith.