THE STATISTICS OF DISCONTINUITIES IN ROCK MASS IN UNDERGROUND WORKS AND ITS APPLICATIONS

Taking the rock mass in coal mines as example, this paper analyses the relation between major and minor discontinuities, proposes a statistical method of discontinuities in rock mass in coal mines, suggests the statistical and calculation methods of the trace spacings in the coexistence of multiple sets of discontinuities in the same rock mass, and show a way to to determine the maximum movable domains of the critical blocks in the roadway and to select the optimum axial direction using these statistical parameters. The result provides a scientific basis for support design of roadways.