Change in seismic activity and rockburst hazard in stoping at SUBR’s Kalia deposit

Abstract

Seismic activity at the rockburst-hazardous deposits of SUBR causes sudden failures in underground excavations in the course of room-and-pillar mining. The regional forecast used seismological observations with determination of coordinates and energy of seismic events. This made it possible to find out that the most of seismic events was connected with natural concentrators: abrupt changes in the thickness of ore bodies down to sterile ground and faulting. Using the kriging method, the contour map was constructed for the sheetlike bauxite deposit thickness in Kalia Mine, in block 5u, Level -1220 m, being mined using the room-and-pillar system. The thickness map of the ore deposit is superimposed on the mining plan. For locating source sites of seismic events relative to the deposit, the vertical sections of the latter were constructed in different directions. The results obtained indicate the susceptibility of the ore body thickness to the effects of seismic events. Using the spatial model section, the seismic circumstances of a rock burst were determined. The numerous studies prove the dependence of energy of a seismic event on the distance between its source and a failure point. The rock mass envelope around an extraction panel where rock falls and failures take place in underground excavations after a seismic event is determined. It is revealed that the total released energy of rocks directly depends on the volume and span of the mined-out stope. With decreasing size of the test block along the strike, the specific energy density increases. The forecast calculation of the total energy of seismic events for the next excavation panel is performed. The procedure to detect the increased energy activity areas is developed. It makes it possible to locate high energy sources in advance.