Geotechnical assessment of the southeast wall slope failure at Highmont Mine, British Columbia

CIM Bulletin, Vol. 81, No. 917, 1988

H. WARREN NEWCOMEN and DENNIS C. MARTIN Piteau Associates Engineering Ltd. West Vancouver, British Columbia

This paper describes the investigation of a large, progressive slope failure on the southeast wall of the east pit at Highmont Mine, British Columbia Geotechnical investigations consisted of geological and structural mapping, assessment ofblasthole drilling records, review of rock core information, slope movement monitoring and back analysis of various possible failure modes. Climate records and mining history were also assessed to determine their relationship to slope movement. Analysis of movement monitoring records and geotechnical information indicates that the failure is deep seated. The upper portion of the failure surface occurs along clay filled discontinuities. The lower portion of the failure surface appears to occur through the highly altered rock mass. High groundwater pressures and mining at the toe of the slope are documented to have had a major influence on stability at various times during the failure. Stability analyses results are presented and possible remedial measures are discussed.
Mots Clés: Rock mechanics, slope failure, Open pit mining, Stability analyses, Structural geology