Rock bolt

Abstract

A rock bolt to be embedded in a borehole and a method of manufacturing a rock bolt, the rock bolt including an extended energy-absorbing part, the first end of the energy-absorbing part including an anchor and the second end of the energy-absorbing part including a screw joint for prestressing the rock bolt. The rock bolt includes an extended tubular part with a jacket and a first end section and a second end section, with an internal dimension that is larger than the external dimension of the energy-absorbing part and arranged in such a manner that it surrounds the energy-absorbing part.

1 . A rock bolt to be embedded in grout in a borehole, comprising an extended energy-absorbing part, the first end of the energy-absorbing part comprising an anchor and the second end of the energy-absorbing part comprising a screw joint for prestressing of the rock bolt, wherein the rock bolt comprises an extended tubular part with a jacket and a first and a second end section, and an Internal dimension of the tubular part that is larger than the external dimension of the energy-absorbing part and arranged in such a manner that it surrounds the energy-absorbing part and that the first end section of the tubular part is connected with the energy-absorbing part in association with the anchor and the second end section is arranged to make contact with a washer that is a component of the screw joint and to make contact with the washer when the rock bolt is prestressed. 
     
     
         2 . The rock bolt according to  claim 1 , whereby the tubular part extends between the anchor and the screw joint and in this way prevents the energy-absorbing part coming into contact with the grout. 
     
     
         3 . The rock bolt according to  claim 1 , whereby the end sections of the tubular part are united with the energy-absorbing part in association with the anchor and the screw joint. 
     
     
         4 . The rock bolt according to  claim 3 , whereby the tubular part is united by means of welding. 
     
     
         5 . The rock bolt according to  claim 1 , whereby the jacket of the tubular part is provided with a structure to increase friction. 
     
     
         6 . The rock bolt according to  claim 1 , whereby the jacket of the tubular part is perforated. 
     
     
         7 . The rock bolt according to  claim 1 , whereby the jacket of the tubular part is provided with lugs. 
     
     
         8 . The rock bolt according to  claim 1 , whereby the energy-absorbing part comprises a reinforcement member. 
     
     
         9 . The rock bolt according to  claim 1 , whereby the energy-absorbing part comprises a wire. 
     
     
         10 . The rock bolt according to  claim 1 , whereby the energy-absorbing part comprises a steel rod. 
     
     
         11 . The rock bolt according to  claim 1 , whereby the energy-absorbing part comprises an extended body of a composite material. 
     
     
         12 . The rock bolt according to  claim 3 , whereby the tubular part is attached by means of welding. 
     
     
         13 . The rock bolt according to  claim 1 , whereby the anchor comprises a wedge introduced Into a slot in the end of the energy-absorbing part. 
     
     
         14 . The rock bolt according to  claim 1 , whereby the anchor comprises a stirring arrangement arranged at the end of the energy-absorbing part. 
     
     
         15 . A method for the manufacture of a rock bolt, comprising the following operational steps:
 that a length and a diameter of the hole in the rock are determined,   that an extended energy-absorbing part is chosen to correspond to the length of the hole in step 1,   that an extended tubular part is chosen to correspond to the length of the hole in step 1 or the diameter of the energy-absorbing part in step 1,   that the energy-absorbing part is adapted inside of the tubular part,   that one end of the tubular part is permanently attached in association with a first end section of the energy-absorbing part,   that the second end of the tubular part is permanently attached in association with a second end section of the energy-absorbing part, and   that the first end and the second end of the energy-absorbing part are arranged with a screw joint and an anchor, respectively.   
     
     
         16 . A method for the manufacture of a rock bolt, comprising the following operational steps:
 that a length and a diameter of the hole in the rock are determined,   that an extended energy-absorbing part is chosen to correspond to the length of the hole in step 1,   that an extended tubular part is chosen to correspond to the length of the hole in step 1 or the diameter of the energy-absorbing part in step 1,
 that the energy-absorbing part is adapted inside of the tubular part, 
   that one end of the tubular part is permanently attached in association with a first end section of the energy-absorbing part,   that the first end and the second end of the energy-absorbing part are arranged with a screw joint and an anchor, respectively, and   that a washer that is a component of the screw joint is arranged in such a manner that it makes contact with the second end of the tubular part.