Predictive Calculation and Practical Observation of Opening Stability due to Alteration of Mining Method, -Predictions and monitorings for rock development design (6th Report)-

Sinji Sakai, Koichi Nishioka and Yoshiaki Mizuta

J. of MMIJ, Vol.112, No.4, p.207-212 (1996)

The New mining method named the drawhole-less method has been adopted recently in Toyoha Mine. The rate of recovery may increase by the new mining method to 84 percent while it was 70 percent by the old mining method in which the drawholes were made every 50 meters upward. However, it was anticipated that an increase of stress concentration in the rock around the openings might have caused fall of hanging rock and failure of rock around the drifts near the mined area. Hence, before the use of the drawhole-less system, the authors investigated the mechanical properties of the rock / ore and the deformation characteristic of the material for back-fill and carried out numerical analyses by the Displacement Discontinuity Method, taking the mechanical characteristic investigated into account. Stability of excavated the openings by the new mining method was studied. The influence of new method on rock behavior around the drifts under the openings was compared to those with the results obtained from the model for the old mining system. In this paper, the results investigated by numerical analyses and behavior of rock around the mined area, which was observed after mining by the new method completed, are described.

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