Self-tapping, and self-tapping and self-drilling, rock bolts

A self-tapping rock bolt for cutting a threaded profile in an internal surface of a pilot hole comprising:

• (a) at least one flute extending along the length of the rock bolt to facilitate removal from the pilot hole of material cut by the rock bolt;
• (b) a hole extending along the length of the rock bolt to enable water to be injected through the rock bolt into the pilot hole as the threaded profile is being cut;
• (c) a discontinuous threaded profile having a plurality of cutting edges, the cutting edges being adapted to cut the threaded profile in the internal surface of the pilot hole, and said discontinuous threaded profile being adapted to interlock with the threaded profile cut in the internal surface of the pilot hole, said discontinuous threaded profile comprising a plurality of segments, each segment extending around the rock bolt from a leading edge to a trailing edge, with the leading edge of each segment defining one of the cutting edges;
• and
• (d) a lead-in section formed by tapering said discontinuous threaded profile such that the height of the leading edge of each segment progressively increases from a leading end of the rock bolt.