Aplicación de Destress Blasting en desarrollo de túneles en ambiente de esfuerzos altos

Abstract

Rock Mass preconditioning techniques, commonly used in the mining industry, can be applied to large scale affecting a significant volume of rock, or to local scale affecting a reduced volume of rock mass around a tunnel during excavation. The latter is the case of the infrastructural tunnels of New Mine Level project, at El Teniente mine (Codelco). Preconditioning methods include the Destress Blasting, which is based on the use of confined explosives that are blasted simultaneously with the construction blast at the tunnel face, this allows to reduce the load transfer capacity around the excavation. This technique has been used in deep mines in Canada and South Africa to reduce the risk of seismic events due to a high stress condition. In this study the authors describe the Destress Blasting technique and its design used in the Personnel Access Tunnel P4600 (TAP P4600) of New Mine Level project. Finally, based on the geological, geotechnical and operational data captured during the works, the preliminary results are given together with a comparison of the seismic behaviour of the rock mass with and without the application of this preconditioning technique