Rockbolts and cables

Rockbolts and dowels have been used for many years for the support of underground excavations and a wide variety of bolt and dowel types have been developed to meet different needs which arise in mining and civil engineering.

Rockbolts generally consist of plain steel rods with a mechanical or chemical anchor at one end and a face plate and nut at the other. They are always tensioned after installation. For short term applications the bolts are generally left ungrouted. For more permanent applications or in rock in which corrosive groundwater is present, the space between the bolt and the rock can be filled with cement or resin grout.

Dowels or anchor bars generally consist of deformed steel bars which are grouted into the rock. Tensioning

is not possible and the load in the dowels is generated by movements in the rock mass. In order to be effective, dowels have to be installed before significant movement in the rock mass has taken place. Figure 1 illustrates a number of typical rockbolt and dowel applications that can be used to control different types of

failure that occur in rock masses around underground openings.

The move towards larger underground excavations in both mining and civil engineering has resulted in the gradual development of cable reinforcement technology to take on the support duties which exceed the capacity of traditional rockbolts and dowels. Some of the hardware issues that are critical in the successful application of cables in underground excavations are reviewed in this chapter.

ANTO Split Set Bolt

ANTO Cable Bolt