To select the correct drill bit diameter for meeting the recommended initial anchorage of 6 to 9 tons, drill several holes with bit diameters ranging from 1-518 to 1-314 inch (41 to 45 mm).
- Drill each hole at least 2 inches (5 cm) longer than the bolt length.
- Number each hole and record the bit size.
In soft ground, a bit may drill a hole larger than its diameter. In hard abrasive ground, the hole may be the same diameter as the bit.
Drive into each hole an SS-46 Split Set stabiliser fitted with a pull collar as shown.
- Record the driving time for each stabiliser. After insertion, observe the amount of slot closure inside each stabiliser.
To determine anchorage, perform a pull test.
- Align the pull tester with the stabiliser, and pressurize it until the stabiliser slips in the hole.
- Watch to be sure that it is actually the stabiliser that has slipped. (When building up the pull load on the stabiliser, various adjustments may occur such as realignment of the tester housing, bearing plate settling, or localized rock crushing. These must not be mistaken for tube slippage.)
Once the bolt has slipped in the hole, pressurize the tester pump until the bolt slips again. The same pull load should cause subsequent slippage.