The problem of mining-induced seismicity in hard rock mines has become more recurrent and significant in underground mines since mining is reaching greater depths as a consequence of the depletion of shallow reserves. This has been a cause of concern for the Cuiabá Mine, where seismicity has increased with the advancement of the mine depth and more cases of fall of grounds have been reported. Thus, in order to avoid production losses, damage and to ensure the safety of workers of this mine, seismic hazard assessment is necessary to the mine project management. For this purpose, this paper focuses on: (i) identifying and understanding of the dominant rock mass failure mechanisms in critical areas of the Cuiabá mine and (ii) developing a preliminary quantitative methodology for assessing the seismic hazard of this mine. Hence, areas with high potential for seismic risk can be identified during mine excavation.
Cuiaba Mine is currently one of the most important deep underground mines in Brazil, which has more than a hundred kilometers of excavations and more than 1,100 m of depth below the surface. It is a hard rock gold mine located in Sabará, 35 km from the capital of the state of Minas Gerais, Belo Horizonte. AngloGold Ashanti has been operating this mine for over 30 years. The underground excavation methodology changed from cut-and-fill to sub-level stoping in 2012, which has improved the production from narrow vein ore bodies and the rock engineering controls (support, design and monitoring). Cuiabá Mine has seven mineralized orebodies, however the current most important are Fonte Grande Sul (FGS) and Serrotinho (SER).
As mining activities are moving to greater depths in FGS and SER, where the rock mass stress is higher, seismic events and excavation damage are occurring more commonly. This represents a hazard to the workers' safety and the economic operation of the mine.
