In situ dynamic drop testing of the MD bolt at Mt Charlotte Gold Mine

Authors: Carlton, R; Darlington, B; Mikula, PA Download Paper

DOI https://doi.org/10.36487/ACG_rep/1304_13_Mikula

Cite As:
Carlton, R, Darlington, B & Mikula, PA 2013, 'In situ dynamic drop testing of the MD bolt at Mt Charlotte Gold Mine', in Y Potvin & B Brady (eds), Ground Support 2013: Proceedings of the Seventh International Symposium on Ground Support in Mining and Underground Construction, Australian Centre for Geomechanics, Perth, pp. 207-219, https://doi.org/10.36487/ACG_rep/1304_13_Mikula



Abstract:
The MD bolt has recently been trialled at Mt Charlotte Gold Mine. Static in situ load testing has demonstrated high anchorage capacities for the MD bolt in this rock mass, but it was not certain how the bolt would perform in dynamic conditions. Therefore a series of drop tests were conducted on bolts installed underground. This was done by suspending a one tonne mass on chains below the test bolt, and then allowing it to fall through 2.1 m before transferring kinetic energy to the bolt at the collar. A high-speed video camera was used to remotely obtain the time–displacement record for each test. The results showed that for the test conditions in this rock mass, the MD bolt will slip along the borehole during a dynamic loading. Bolt slip ranged from 23 to 503 mm per impact, and calculated bolt forces applied to the bolt ranged from 40 to 105 kN. This testing provides confidence that the bolts do have significant dynamic capacity, and can be utilised accordingly within ground support schemes at the mine.

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