STABILITY ANALYSIS OF HORIZONTAL AND VERTICAL PASTE FILL EXPOSURES AT THE RALEIGH MINE

9th International Symposium on Mining with Backfill
Robert Urie,
Abstract The underhand longhole bench extraction strategy at EKJV Management Pty Ltd’s Raleigh Mine requires simultaneous horizontal and vertical exposure of paste-filled stopes. In order to prevent excessive ore dilution, the paste fill must be of sufficient strength to prevent excessive failure during exposure.

A numerical modeling methodology has been developed to accurately simulate the initial stress distribution within paste-filled stopes, together with the strain-softening loading response of paste fill material. Due to the narrow orebody width and high deformation behavior of the host rock mass, high closure strains are likely to cause a stiff, brittle fill material to undergo crushing failure upon exposure.

The stability of paste fill exposures at the Raleigh Mine was determined by conducting a series of three-dimensional numerical models that incorporate the extraction, filling and exposure sequence of paste-filled stopes. Stability charts for 2.5 m and 3.5 m wide simultaneous horizontal and vertical exposures have been derived based upon the numerical modeling results. Implementation of the stability charts has proved successful in limiting the amount of dilution and provides a basis to optimize paste fill cementation and stability throughout the life of the mine.
Keywords: Paste fill, Numerical modeling, Exposure Stability
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