Determination of the Stress in Rock Unaffected by Boreholes or Drifts from Measured Strains or Deformations

Abstract

The present paper treats the problems regarding determination of the stress in the rock unaffected by boreholes or drifts from measurements made in them. As the items of measurement, we can mention variations in borehole diameter, strains on the bottom surface of boreholes, strains of the wall surface of boreholes, variations in oblique dimension of boreholes and combinations of these as well as strains on the wall surface of drifts or shafts. The formulae to be used in practice to determine the stress in the rock from several measurements have been presented. On deducing them, the elastic constants of the rock, the rigidity of the measuring instruments used and the irregular distribution of strain within the range of each strain gauge were taken into account. The least number of boreholes or drifts necessary for each stress determination and the accuracy in the results obtained have also been discussed.