Geomechanical assessment of groundfall hazards in a small-scale underground mine in the arequipa region, Peru

Contreras Inga C.E.; Quispe Aquino R.; Canahua Loza R.; Taco Prado L.; Walton G. · 54th U.S. Rock Mechanics/Geomechanics Symposium (2020)

Resumen

Gedeon mine is a small-scale mining operation in the Nazca-Ocona gold belt in southwestern Peru. It is a gold vein deposit hosted mainly by granodiorites of the Coastal Batholite, in the Rio Grande district, Arequipa region. For this study, the rock masses of Gedeon mine were geomechanically characterized in the underground workings along the Fortuna vein through manual mapping, and Schmidt hammer rebound tests. According to the characterization, three different rock units were identified: host granodiorite with GSI of 55-75, orebody with GSI of 40-65, and a fault zone with GSI of 30-50. Deficiencies in the design and execution of drilling, blasting, and excavation procedures were identified, which can lead to rock mass degradation and overbreak in the walls of the excavations. A series of numerical models were developed based on these data, which were then used to assess the stability of the stopes along the Fortuna vein. In the stopes, we found that the quality of the rock mass of the fault zone controls the stability of the excavations. Also, damage due to poor quality blasting and deviations in the excavation geometry may contribute to instabilities in the hanging wall but they are not the primary reasons for the instabilities.

Instituciones: Universidad Nacional de San Agustín de Arequipa