| 摘要 |
This invention relates to a rock bolt or roof anchor (1), in particular to a rock bolt or roof anchor for use in an underground mine, or other tunnel. The invention also relates to a method of reinforcing a wall or ceiling in an underground mine or tunnel. In particular, the invention relates to a dowel, for example, a Rima dowel or coal rib anchor for use in a coal mine. The rock bolt (1) of one embodiment of the invention comprises: a shaft (2) having one end (5) threaded to receive a nut, the other end (6) being provided with a plurality of surfaces (3, 3a, 3b), each surface extending angularly about and longitudinally of the longitudinal axis of the shaft (2), and converging with respect to the axis towards the one end (5); and a plurality of collars (4, 4a, 4b), each collar (4, 4a, 4b) being associated with a respective one of the surfaces (3, 3a, 3b) and co-operating therewith so that upon relative movement of each collar (4, 4a, 4b) with respect to its associated surface (3, 3a, 3b) toward the other end, each collar (4, 4a, 4b) is caused to radially expand so as to project radially beyond its associated surface (3, 3a, 3b).
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