Analysis of the failure of a large hangingwall wedge: Kidd Mining Division, Falconbridge, Ltd.

CIM Bulletin, Vol. 93, No. 1043, 2000

M. Board, Itasca Consulting Group, Minneapolis, Minnesota S. Seldon, Kidd Mining Division, Falconbridge, Ltd., Timmins, Ontario R. Brummer, Itasca Consulting Group, Sudbury, Ontario, and R. Pakalnis, The University of British Columbia, Vancouver, British

The Kidd operation mines roughly 10 000 tpd of copper and zinc ore from underground and employs about 700 personnel. In the late summer and fall of 1997, major movements in the proximity of the east wall of the Kidd open pit had been observed. The Kidd pit had been mined from 1965 to 1977 to depths of 260 m (850 ft), followed by subsequent mining by underground methods to current depths in excess of 1830 m (6800 ft). The No. 1 Mine (2600 Level to pit bottom) is approximately 90% extracted, with most of the remaining reserve between 2000 and 2500 levels. Although initial concerns centred on the stability of the pit walls, the potential ramifications of the movements to the underground were recognized and measures were implemented to ensure the safety of personnel as well as to minimize the potential damage to existing operations. In late October, damage to underground operations was observed as deep as the 2000 Level. In the final assessment, the global mobilized mass was a ÒwedgeÓ-shaped hangingwall block extending from surface to about 610 m (2000 ft) below surface. The ÒwedgeÓ boundaries are d
Keywords: Rock mechanics, Kidd operation, Open pit mining.