A friction rock bolt assembly is arranged to frictionally engage an internal surface of the bore formed in rock strata. The rock bolt includes a loading mechanism provided at a rearward end of the rock bolt having a load absorber to absorb an initial predetermined loading force followed by transfer of the force to a main load element.

Disclosed is a method of adapting a metal bar, for use as a rock bolt, to ensure that the bar will break in a predictable manner, the method including the step of removing material from the bar in a circumferential band to reduce a diameter of the bar within the band to a minor diameter thereby to provide a failure zone within which the bar will break if subjected to enough tensile load.

A self-drilling rock anchor assembly includes: a friction fit tubular sleeve extending longitudinally between leading and trailing ends; a rod extending through the sleeve between first and second ends, and projecting from each sleeve end; a drill bit member engaged with the rod's first end having an exterior surface part of which tapers towards a back end of the member; a backstop element engaged with the rod's second end having a first drive surface; a load bearing element on the rod between the sleeve's trailing end and the backstop that has a second drive surface. The rod moves relative to the sleeve between a drill position, wherein the drill bit is spaced from the sleeve's leading end, and an insertion position, wherein the sleeve's leading end abuts the bit. The drill and insertion positions are achieved by applying a force to the first and second drive surfaces, respectively.

A self-drilling rock anchor assembly includes: a friction fit tubular sleeve extending longitudinally between leading and trailing ends; a rod extending through the sleeve between first and second ends, and projecting from each sleeve end; a drill bit member engaged with the rod's first end having an exterior surface part of which tapers towards a back end of the member; a backstop element engaged with the rod's second end having a first drive surface; a load bearing element on the rod between the sleeve's trailing end and the backstop that has a second drive surface. The rod moves relative to the sleeve between a drill position, wherein the drill bit is spaced from the sleeve's leading end, and an insertion position, wherein the sleeve's leading end abuts the bit. The drill and insertion positions are achieved by applying a force to the first and second drive surfaces, respectively.

A rock anchor assembly includes: a resiliently radially deformable tubular member longitudinally extending between leading and trailing ends and which has an arrestor formation integral with, or engaged to, a trailing end part of the member; an elongate element longitudinally extending through the member between first and second ends and which attaches to the tubular member at spaced distal and proximal load points and which has a failure arrestor fixed at a point within the member; and a faceplate on the tubular member or the elongate member. When the assembly is inserted in a rock hole, with the faceplate bearing against the rock face, and load is applied along the elongate element that will cause the element to sever above the point at which the arrestor is fixed, the failure arrestor engages the arrestor formation, arresting the ejectment of a proximal portion of the elongate element from the hole.

A reaming and self-rotating anchor rod includes a rod body, a drill bit, a connecting member, a tray, and a nut. One end the connecting member is snap-fixed to the tail part of the rod body, the other end of the connecting member is connected to an anchor rod bolter. The rod body has an annular protrusion at its middle part to block powder so that the powder fills up the clearance between the rod body and the coal mass. The drill bit has female threads and can be screwed into the front part of the rod body, and the drill bit has baffle pawls and spiral grooves on its side surface.

A friction bolt assembly to frictionally engage a bore formed in rock strata. The assembly includes an elongate tube and an expander mechanism acted on by an anchor mechanism via an elongate bar or cable. A retainer mechanism is mounted to act between the bar or cable and the tube to prevent ejection of the bar or cable from the assembly should the bar or cable break.

The present invention provides a reaming and self-rotating anchor rod and a construction method using the reaming and self-rotating anchor rod, which are applicable to supporting for quick tunneling of coal roadways. The reaming and self-rotating anchor rod comprises a rod body, a drill bit, a connecting member, a tray and a nut; one end the connecting member is snap-fixed to the tail part of the rod body, the other end of the connecting member is connected to an anchor rod bolter, the rod body has an annular protrusion at its middle part to block powder so that the powder fills up the clearance between the rod body and the coal mass; the drill bit has female threads and can be screwed into the front part of the rod body, and the drill bit has baffle pawls and spiral grooves on its side surface; a hole in length smaller than the length of the anchor rod is drilled out with an anchor rod bolter first, and then the anchor rod is connected to the anchor rod bolter, the drill bit on the front part of the anchor rod is placed in the preformed hole, and finally the anchor rod is driven to ream and rotate into the coal mass, so as to accomplish the construction with the reaming and self-rotating anchor rod; the reaming and self-rotating anchor rod can shorten supporting time and avoid an abandoned borehole phenomenon incurred by hole collapse or blockage, and anchoring failure, etc., and the anchor rod is simple to manufacture, low in cost, and simple and convenient to operate. Therefore, the anchor rod and the method of using it can be widely applied and can meet the requirement for quick tunneling of coal roadways.

A rock bolt (10) is provided for frictionally engaging with the internal surface of a bore drilled into rockmass. The bolt comprises a tube having a circular cross-section (12) defining a longitudinal split (14) and a longitudinal axis (10a). The tube (12) in is radially expandable. The bolt (10) has a first leading end (12b) for insertion into a bore, a second end defining a head (12a) and expander means (30) for expanding the diameter of the tube at least one location along the tube. The expander means comprises first (42) and second (44) expander/wedge elements arranged so that relative movement of the two elements causes the diameter of the tube to expand at that location. The first expander element (42) is mounted on an elongate rod (30) which is aligned generally along the longitudinal axis of the tube. Rotation of the rod (30) causes the relative movement of the two elements to cause the diameter of the tube to expand at the location. The rock bolt includes an arrestor (100) in the form of a ring, which defines an aperture which locates on the proximal end of the rod (30). The aperture is larger than the proximal end of the rod so that the arrestor is able to move along the proximal end of the rod. The arrestor includes a laterally extending protrusion (102) which locates in the longitudinal split (14) and is narrower than the longitudinal split and which is configured to engage with the head of the friction bolt when moved towards the proximal end of the friction bolt.

A friction rock bolt assembly is arranged to frictionally engage an internal surface of a bore formed in rock strata. The rock bolt includes an expander mechanism having at least two radially outer wedge elements engageable by an inner wedge element. The expander mechanism is configured for symmetrical displacement of the expander elements to provide controlled enlargement by the rock bolt within the borehole for secure anchorage.