This paper describes ongoing research at PT Freeport Indonesia in which the main goal is to use micro seismic information recorded as a result of mining to analyse cave propagation and stress performance on the actual production and fixed infrastructure. At the moment, several numerical experiments have been conducted in order to correlate the mining activity with the micro seismic events using data collected during the years 2005 and 2006. As a result of the preliminary analysis a micro and a macro cracking envelop is proposed based on the computation of stress behaviour at the location of the events. Stresses have been computed using standard elastic continuous boundary element models. The correlation between average source radius together with the stress performance have provided a method to propose a macro cracking criteria. Several techniques have been tested in order to nucleate the micro seismic activity around different geological features. This last attempt was aimed at looking at potential over stresses induced over the undercut and extraction level drifts. A method was devised in order to integrate the micro seismicity into a 3-D ride distribution model.


Cave mining induces micro seismicity in the rock mass as a result of fracturing processes that take place above and below the production and haulage level as reported by Glazer & Hepworth (2004) and Dunlop & Gaete (1995). Micro seismicity induced by mining in high stresses in brittle rock masses has been researched for years in order to find a pattern between micro seismic activity and violent failure in the form of a rock burst as shown by Simser & Falmagne (2004), while Beck & Brady (2002) have proposed a parametric formulation to evaluate the controlling parameters for seismic events in hard rock mining.

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