ABSTRACT
Friction rock bolts or stabilizers have been tested and compared with conventional prestressed mechanical bolts by the Mining Division of the Norwegian Institute of Technology during the période 1979–1982. Practical tests including convergence measurements and pull tests have been carried out in three different mines. Both Split sets and Swellex bolts have been investigated. Convergence measurements show that Split Set bolted sections of drifts have slightly higher convergence than conventionally bolted sections. Pull out tests show that the pull force needed for Swellex bolts is at least three times that of Split Sets. Bit diameter wear creates considerable problems with the installation of Split Sets as the hole diameter becomes too small. This has in turn made it difficult to get the systems accepted by the miners. The Swellex system is virtually independent of the hole diameter within quite large limits, and the system was much easier accepted by the miners. Systematically friction bolted roof sections seem to be fully equivalent to or even better than conventionally bolted sections.
