The recently developed Pretec Dynamic Rock Bolt is an energy- absorbing bolt that satisfies current demands for bolts in environments where there are significant rock stresses.
The bolt has an efficient design with an end anchor comprising an R22 thread and a rolled M24 for installing washer and nut. The mid-section is smooth. The smooth surface makes it possible for the smooth section to move unhindered and thereby be fully activated when loaded.
Pretec Dynamic Rock Bolt’s energy- absorbing capacity has been asses- sed in dynamic tests performed at Canmet Mining in Canada. Both the threaded and the smooth sections were loaded dynamically with good results.
The bolt can be supplied with an optional, expandable anchor wedge that provides the potential to preload the bolt slightly before the cement paste hardens.