Geodynamic rock condition, mine workings stabilization during pillar recovery at the level +320 m of the Yukspor deposit of the Khibiny Massif

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.