Numerical modeling analysis for Sao Bento Mineracao S/A, Santa Barbara, MG, Brazil

The Sao Bento Mineracao gold mine is located in the eastern portion of the Iron Quadrangle mining district in Minas Gerais, Brazil. Currently the mining operations are in weak rockmass and at depth in excess of 1,000 m. Poor ground conditions and the increase in in-situ stress provide challenges to the stability of underground openings and safety to personnel. The conditions of the highly schistosed ground at depth are formed by shears and faults. The deterioration of underground excavations within the location of these shears and faults are brought upon by weak rockmass and increased ambient stresses at depth. A rehabilitation program was formed in March to May of 2005 to rehabilitate the effected areas for production. The mine has dealt with these conditions by strategically implementing appropriate ground support, thus allowing the continuation of mining activities. This paper summarizes the ground conditions, the mechanics of failure and innovative use of support techniques to improve the design within the defined rockmass at Sao Bento Mineracao. A comparison of numerical stress predictions was performed with Phase2 on established design criteria and underground observations.