Abstract

The article represents the results of seismic monitoring during pillar recovery at the level +320m of the Yukspor deposit. The number of seismic events with an energy of more than 106 J is sharply increasing in the affected area of overlying rock base. This reflects fracture intergrowth and gradual rock failure due to stress redistribution. Mining operations cause new fractures and interstices, which in turn lead to residual stress redistribution through the formation of new defects. During the rock failure, stresses in the affected area become stable. If fracturing and timely rockfall of overlying rock base do not occur during excavations, thereafter, sudden caving poses a hazard by an underground air strike and can be a threat to the objects on surface. As for stability of mine workings, provoked gradual rock fall does not pose a threat, since this leads to consequent and constant reduction of the mountain base, and, therefore, support pressure, hanging walls become more stable. Underground seismic monitoring based on continuous seismic registration, local monitoring through various geophysical measurements and mathematical modeling of stress-strain rock condition improve the operational safety under difficult geodynamic conditions.

Highlights

  • Up to date, Kirovsk branch of JSC "Apatit" is one of the world's largest enterprises for the production of apatite concentrate

  • The development of three sublevels of the level + 320m of the Yukspor deposit showed that all of the above factors are relevant for the conditions of the mines of Kirovsk branch of JSC "Apatit" and significantly affect the safety of mining operations

  • Local forecasting of rock-bump hazard based on continuous registration of seismic activity increases mining safety under difficult geodynamic conditions

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Summary

Introduction

Kirovsk branch of JSC "Apatit" is one of the world's largest enterprises for the production of apatite concentrate. The exploitation of apatite-nepheline ores at Kirovsky and Rasvumchorr mines is carried out using an underground method of induced sublevel caving. The technology for rockburst conditions, the methods of rock monitoring and mine workings stabilization were proposed. - pillar mining in the affected area and rock pressure increase cause dynamic rockfall, strainburst on the outline of the excavations and pillar bursting;. The development of three sublevels of the level + 320m of the Yukspor deposit showed that all of the above factors are relevant for the conditions of the mines of Kirovsk branch of JSC "Apatit" and significantly affect the safety of mining operations. To prevent negative effects of rock pressure, the Department of rockburst forecasting and prevention was established in Kirovsk branch of JSC "Apatit".

Seismic monitoring
Seismic analysis
Rock stability and status categories of mine workings during pillar recovery
Conclusions
Full Text
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