Ground vibrations originated by rock blasting with use of explosives. Case study: calcareous quarry of Cruzeiro, Limeira (SP).

Abstract

This study performs a ground vibrations monitoring generated by blasting in a calcareous and clay quarry in the Municipality of Limeira, State of São Paulo. The main objective is to develop a scaled distance equation and verify the existence of ground vibration levels variation in blasting of different lithological and stratigraphical layers. Peak particle and frequency registrations were measured by engineering seismographs in an area named Bairro Belinha Ometto located 300 meters southwest from the mining site. The data acquisition had been carried in two stages. A scaled distance equation was generated in the first one and was used by the Company in ulterior blasting, reducing population annoyance. PPv values obtained in successive stage of monitoring have indicated that the deviation of the nominal time delay in blasting accessories is the main factor for the dispersion of the PPv resultant. Blasting design with MS delay intervals lesser than 25 ms between holes or between rows and MS delays higher than 200 ms in the initiation system (explosive column) was considered improper in this study.