ABSTRACT
Large diameter shafts have been used in Brazil since the 1980s, usually in mass transport projects such as metro stations, ventilation shafts, emergency exits and auxiliary structures. When in soil, the advance is done in partial excavations with the application of deformable shotcrete lining as the excavation proceeds, but for rock shafts, the excavation and mucking of the material must be preceded by rock desegregation techniques, which may be done by blasting or by mechanical methods, if there are restrictions on the use of explosives. This paper describes the methodology and processes involved in the successful excavation of a large deep shaft in granite with approximately 40.0 m diameter and 40.0 m deep in a high dense urban area. Special focus is given to the detailed blasting plans and vibration output as well as the measures applied to avoid flyrock debris including a newly developed solution.
