Stress-Strain Analysis of Rock Mass-Support System in Complex Geomechanical Conditions of the Almaz-Zhemchuzhina Deposit of Chromite Ore
T. F. Kharisov, A. E. Balek, D. V. Prishchepa, D. A. Koptyakov, N. A. Masal’skii
Institute of Mining, Ural Branch, Russian Academy of Sciences, Yekaterinburg, Russia
Keywords: Geomechanical monitoring, rock mass-support system, stress-strain behavior, stope wall convergence, unstable rock mass, plastic deformations, stability prediction
Abstract
The article describes in-situ geomechanical observations over deformation in the rock mass-support system in the conditions of the post-limit stress-strain behavior of rock mass at the Almaz-Zhemchuzhina deposit of chromite ore (stability categories IV-V). The methodology framework was monitoring of convergence of stope walls using a band extensometer at 27 deformation stations set both inside and outside influence zones of stoping. Two modes of deformation were identified: background deformations (rate to 1.37 mm/month) and induced deformations with the increased rate of convergence to 72 mm/month (2.4 mm/day). It is found that the extracted ore volume and the displacement velocities are interrelated. An increase in the monthly average volume of ore drawing from 40 to 80 Kt increases the average rate of convergence by 30% (from 0.65 to 0.92 mm/day). The critical deformations are recorded, leading to failure of shotcrete lining, which governs transition to the predictive-preventive stability control in mine stopes.
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