Study of rock stability in large scale underground mining at Tonglushan mine

Large open stope mining methods are used at Tonglushan Mine in China. Frequent rockfalls within stopes had interrupted production in the past and this has necessitated review and reconsideration of the design. Major factors in the assessment of stope stability wre discussed in this paper. Stope design has been evaluated, in the first instance, using rock mass classification and stereographic techniques taking anticipated discontinuities into account. Numerical techniques were then applied to evaluate the behavior of the stopes under a variety of conditions. Tomography has also been used as a practical tool to assess the impact of blast design on the stability of the rock mass. Key risk factor analysis has been carried out to assess the sensitivity of the safety to stope stability. Techniques for controlling the stability, that take the results of analysis into account, were discussed.