Summary

The problems connected with rock burst hazards and rock pressure control at the longwall faces and horizontal workings are presented on the basis of a long-range plan of mining in the Westfalen mine. A forecasted distribution of rock pressure in principal stages of the implementation of a mining plan is the starting point of considerations. This distribution can be determined approximately with using a calculation program prepared by "Bergbauforschung" at Essen. If the distance between the seams is less than 60 m, numerous rock burst s occur in a top seam of the working along the border line of the worked out area on the side of undisturbed rock mass. According to calculations of pressure, it corresponds to the difference of pressures occurring in the part of the working over which mining work is carried out and in the remaining part accounting for 30 percent. Such a difference of pressures takes place when mining a residual pillar with the distance between the seams as much as 140 m. A size of strains for a given working is measured by means of an index which depends on the geological structure of rock mass, cross-section of the working and on the supports, and may be determined without difficulty. The convergence in the sections of workings planned in the same seam may be forecasted with the use of this index. A change of mining system may prevent the formation of the zones of increased pressures. A calculation program allows to choose the most favourable mining plan

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