Expandable Bolt With Thrust Element

Abstract

The present invention includes a rock bolt having a longitudinally expandable tube. The tube includes a longitudinally extending depression that defines a temporary enclosed longitudinal passageway. The rock bolt further includes a shielded distal end to prevent debris from entering the temporary enclosed longitudinal passageway. The distal end includes a thrust element that facilitates movement of loose material across the rock bolt as it is advanced in a borehole. The present invention also includes a method of making such a rock bolt and a method of using such a rock bolt.

The invention claimed is: 
     
         1 . A rock bolt comprising:
 an expandable tube having a longitudinally extending depression disposed between a pair of outer portions of the tube, wherein the exterior of the tube defines a temporary, enclosed longitudinal passageway; and   a thrust element positioned at a distal end of the rock bolt to facilitate movement of material past the rock bolt when installed in a borehole.   
     
     
         2 . The rock bolt according to  claim 1 , wherein the thrust element includes a plurality of projections and at least one channel between the projections that facilitates material flow across the rock bolt as it is advanced in a borehole. 
     
     
         3 . The rock bolt according to  claim 1 , wherein the thrust element is tapered from a thrust end to an engagement end. 
     
     
         4 . The rock bolt according to  claim 1  wherein the thrust element includes a plurality of facets extending between the thrust end and the engagement end. 
     
     
         5 . The rock bolt according to  claim 1 , further comprising a cover covering the temporary longitudinal passageway, wherein the thrust element is adapted to engage with, or form part of the cover. 
     
     
         6 . The rock bolt according to  claim 1 , further comprising a stiffener tube surrounding the distal end of the expandable tube, wherein the thrust element is adapted to engage the stiffener tube. 
     
     
         7 . The rock bolt according to  claim 6 , wherein the thrust element comprises an engagement portion received within the stiffener tube. 
     
     
         8 . A method of using a rock bolt comprising:
 providing a rock bolt comprising an expandable tube having a temporary enclosed longitudinal passageway with an open distal end and an end fitting, and a thrust element at a distal end of the expandable tube covering the temporary longitudinal passageway;   inserting the rock bolt in a borehole, whereby material in the borehole is deflected by the thrust element as it is advanced in the borehole;   expanding the tube by providing pressurized fluid to the interior of the tube, thereby providing frictional engagement between an exterior of the tube and an interior of the borehole; and   draining the fluid from the interior of the tube.   
     
     
         9 . The method according to  claim 8 , wherein the thrust element includes a plurality of projections and at least one channel between the projections. 
     
     
         10 . The method according to  claim 8 , wherein the thrust element is tapered from a thrust end to an engagement end. 
     
     
         11 . The method according to  claim 8 , wherein the thrust element includes a plurality of facets extending between the thrust end and the engagement end. 
     
     
         12 . The method according to  claim 8 , further comprising a cover covering the temporary longitudinal passageway, wherein the thrust element is adapted to engage with, or form part of, the cover. 
     
     
         13 . The method according to  claim 8 , further comprising a stiffener tube surrounding the distal end of the expandable tube, wherein the thrust element is adapted to engage the stiffener tube. 
     
     
         14 . The method according to  claim 13 , wherein the thrust element comprises an engagement portion received within the stiffener tube. 
     
     
         15 . The method according to  claim 8 , wherein the rock bolt is inserted into a borehole with a percussive force.