Day, AP & Seery, JM 2007, 'Monitoring of a Large Wall Failure at Tom Price Iron Orre Mine', in Y Potvin (ed.), Proceedings of the 2007 International Symposium on Rock Slope Stability in Open Pit Mining and Civil Engineering
, Australian Centre for Geomechanics, Perth, pp. 333-340.
Towards the end of 2006, routine Electronic Distance Measurement (EDM) prism monitoring highlighted
rapid acceleration of one prism. At this stage, there were no visible signs of failure close to the prism and all
other monitoring points in the vicinity could no longer be read. The prism itself was situated on a berm that
was no longer accessible. A week later the prism was still accelerating with the only evidence of wall
movements being two sets of cracks, one 30 m below the prism near the pit floor and the other about 50 m
above the prism, suggesting the possibility of a large scale wall failure. A GroundProbe Slope Stability
Radar was available for a few days and was deployed to scan a large section of wall. After a day of radar
monitoring it was apparent that movement was occurring over an area approximately 265 m wide and
nearly 100 m high. Movement rates were up to 30 mm per day and accelerating rapidly. The eastern half of
the pit below the affected area was closed off and failure commenced two days later. The radar remained at
the site for the initial part of the failure allowing correlation of movement rates and magnitudes with those
recorded by prism monitoring.
It appears that the failure mechanism is a combination of sliding on a fault plane, sliding on the contact
between the Footwall Zone and the Mount McRae Shale and rock mass failure through the Dales Gorge
Member to produce significant floor heave at the base of the failure.
Rocscience (2005) SLIDE Version 5.0, Rocscience Inc., Ontario, Canada,
Monitoring of a Large Wall Failure at Tom Price Iron Ore Mine A.P. Day, J.M. Seery
340 Slope Stability 2007, Perth, Australia