US Patent 7445406 Rock bolt

An anchor device which includes a pipe (16), an elongate member (18) which is partly inside the pipe and which has an end (20) which protrudes from the pipe (16), and a restraining component (22) which is engaged with the protruding end (20). The pipe (16) and the elongate member (18) are shaped with a plurality of deformations along their respective lengths such that the elongate member (18) can only be withdrawn from the tubular member (16) by further deforming the elongate member (18).