Self Drilling Rock Bolt (SDRB) system provides higher tensile strength than conventional solid bolts

Self drilling rock bolt can be used for permanent support project in medium and good rock condition and foundation support. By doing pressure grouting, it can help to reinforce the broken rock mass, improve the rock mass and prevent the corrosion from underground water and then reach the purpose of supporting.
Self-Drilling rock bolt is used to attach objects or structures to concrete. There are many types of Self-Drilling rock bolts, consisting of designs that are mostly proprietary to the manufacturing companies. All consist of a threaded end, to which a nut and washer can be attached for the external load.
A new Self Drilling Rock Bolt (SDRB) system has been developed which uses a pumpable resin system for full column resin encapsulation for immediate roof and rib support. A new drilling and injection system has also been developed to enable fast and efficient bolt installation.
This new SDRB provides higher tensile strength than conventional solid bolts, and also provides a load transfer capacity that is almost double that of conventional bolts. This new SDRB uses low viscosity pumpable resin to ensure full encapsulation right down to the collar.

This not only provides a high load transfer capacity over the entire
length of the bolt, but also reduces the potential for bolt corrosion and locks the bearing plate and mesh in place at the borehole collar.

It will also reduce the amount of water inflow from the roof in mines which have water problems. The advantages of this alone are considerable.
The installation system is also new and consists of a new drill chuck and resin pump which can be retro-fitted onto a continuous miner.

Production versions of the installation system can have full PLC control to further refine bolt installation to have full semi-automatic bolt installation. In addition, resin cure times can be adjusted to suit mine roof conditions such that the resin cure time coincides with full resin encapsulation of the bolt to further reduce installation cycle time.
The current SDRB installation cycle has not yet been fully optimised, and further reductions in bolt cycle time are possible. Nevertheless, the current SDRB installation cycle times for a 2m long bolt are typically 60 seconds,  compared to 150 seconds for a conventional bolt in the same roof.
The full benefits of SDRB technology to the coal industry will only be obtained if these bolts are installed at the face. In the immediate future, this requires retro-fitting the SDRB equipment onto existing continuous miners, and some miners are better suited to this application than others.
This new SDRB uses semi-automatic bolt installation with manual placement of the bolt into the drill chuck, which greatly simplifies the whole installation process. Although a longer term goal would obviously be to have full bolting automation, with bolt handling into the drill chuck to remove operators from unsupported roof. Consideration needs to be given not just to the bolting process itself, but also to the materials re-supply to the machine. This will be essential if high roadway drivage rates are to be achieved.
Longer term the coal industry should encourage machine manufacturers to design and produce machines that are better suited to SDRBs and to full bolting automation.