Hazard identification, stability assessment and risk mitigation overview of near-surface openings and pillars at the former Mine Principale, in Chibougamau, Quebec

Eliane Cabot, Adam Coulson, James Tod, Scott McNicoll, Simon Delattre, Henrik Rasmussen, Carl Gauthier

In the proceedings of: GeoSt. John's 2019: 72nd Canadian Geotechnical Conference

Session: Rock Mechanics

ABSTRACT: Mine Principale refers to the historic Campbell, Kayrand and Merrill mines near Chibougamau, Quebec. The copper-gold sulphide deposit, hosted in an anorthosite rock mass, was mined via underground and open pit from 1953 to 2005. A closure plan, complying with local regulations, was established based on the results of an exhaustive historical-data review, 3D-model construction of near-surface openings and site investigation campaign to confirm the locations of the openings and rock properties for stability analysis. Remediation work started in 2018 and included collapse-blasting of thin crowns, backfilling of underground stopes either from surface or via 12-inch-diameter boreholes, stabilization of thicker crowns with galvanized anchors, and capping of raises with concrete slabs. This paper presents the site conditions, describes the construction of the 3D model, summarizes the findings of the field program, discusses the results of the near-surface stability analyses, shares the risk mitigation and remediation approaches used, and concludes with ongoing monitoring observations.

RÉSUMÉ: Mine Principale est le nom donné aux mines Campbell, Kayrand et Merrill qui ont été exploitées de 1953 à 2005. Le gisement de cuivre-or était encaissé dans northosite. Un plan de fermeture a été établi après une revue exhaustive des données historiques, la construction ddes ouvertures souterraines et la réalisation e ces ouvertures et les propriétés du massif rocheux pour fin a remise en état a commencé en 2018 et comprenait le dynamitage de piliers de surface, le remblayage des chantiers souterrains à partir de la surface ou via des trous de foragerecouvrement de monteries. Cet article présentera les conditions du site, la construction du modèle 3D, les résultats de chantier et danalyses de stabilité, la gestion des risques, les méthodes de sécurisation utilisées et le programme de surveillance en cours.

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