Abstract :
Russia’s coal industry has a clear trend towards increasing load on mining faces equipped by coal-face systems. With increase of coal-face equipment output, financial losses from the equipment downtime also increase. Downtime of fully-mechanized faces can have different causes, but downtime in disassembly is inevitable, and for this reason, minimizing downtime duration is paramount for improving mines operations efficiency. The main causes of repositioning duration increase are roofing rocks collapses into the work area, the most intensive collapse of roofing rocks occurs at the end sections of a recovery room. One of effective modes of enhancing the stability of roofing rocks is rocks destressing. The study objective is determining the parameters of destressing recovery room immediate roofing rocks in developing a gently-sloping thick coal seam on the base of the finite element mining and geomechanical model. The paper describes the methodology of developing a model and design models for assessing the components of the stress-strain state of the coal-bearing massif in the area adjacent to the recovery room. Assessment was conducted of the parameters of limit state zones in a coal seam and in the roofing rocks of the recovery room. Justification was provided for the parameters of the mode of immediate roofing destressing from the stresses at the end sections of the recovery room via drilling relief boreholes. The determined parameters of the technology include: the width of the destressing zone, the depth of the relief boreholes, their diameter, the boreholes’ spacing interval and the period of time until the passage of the longwall, for which they must be drilled
Keyword :
gently-sloping coal mines, underground mining of coal, longwall face move, recovery room, destressing of massif, stability of immediate roof, stressstrain state, relief boreholes.