Rock Mechanics and Rock Engineering

, Volume 18, Issue 2, pp 107–130

Applicability of the theory of hollow inclusions for overcoring stress measurements in rock

  • Bernard Amadei
Article

Summary

Whenever solid or hollow inclusions are used as instrumented probes in overcoring techniques, “residual stresses” remain in the overcored rock sample and in the probes. When using such devices for computing the in-situ stress field components from measured strains or displacements, it is common practice to assume that the overcoring diameter is infinite and that there is a perfect bonding between the rock and the probes. The validity of these assumptions depends on the magnitude of the residual stresses at the rock-probe contact as compared to the tensile and shear strengths of the rock-probe bond material. It also depends on the distribution of residual stresses in the overcored sample.

In comparison to previous work, new expressions are proposed in this paper for the residual stresses associated with solid or hollow inclusion type stress probes in anisotropic ground. These expressions are presented in dimensionless form and are used to show that the distribution and magnitude of residual stresses depend on the isotropic-anisotropic rock character, the degree and type of rock anisotropy, the orientation of the rock anisotropy with respect to the hole in which the probes are located and the relative deformability of the rock with respect to the deformability of the material comprising the probes. The conditions that are required for neglecting the overcored sample diameter are also discussed. This is shown for rocks that can be described as isotropic, transversely isotropic and orthotropic materials.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Amadei, B. (1983): Number of Boreholes to Measure the State of Stress in situ. Proc. 24th U. S. Rock Symp., Texas A & M Univ., pp. 87–98.Google Scholar
  2. Amadei, B. (1982): The Influence of Rock Anisotropy on Measurement of Stresses in situ. Ph. D. thesis, Univ. of California, Berkeley. Also published by Springer-Verlag in: “Lecture Notes in Engineering,” series under the title, “Rock Anisotropy and the Theory of Stress Measurements,” (1983).Google Scholar
  3. Amadei, B., Walton, R. J. (in preparation): Analysis of Data Obtained with the CSIRO Cell in Anisotropic Rock Masses. CSIRO report.Google Scholar
  4. Becker, R. M. (1968): An Anisotropic Elastic Solution for Testing Stress Relief Cores. U. S. Bureau of Mines, RI. 7143.Google Scholar
  5. Becker, R. M., Hooker, V. E. (1967): Some Anisotropic Considerations in Rock Stress Determinations. U. S. Bureau of Mines, RI. 6965.Google Scholar
  6. Berry, D. S. (1968): The Theory of Stress Determination by Means of Stress Relief Techniques in Transversely Isotropic Medium. Tech. Report No. 5-68, Missouri River Division, Corps of Engineers, Omaha, Nebraska.Google Scholar
  7. Berry, D. S. (1970): The Theory of Determination of Stress Changes in a Transversely Isotropic Medium Using an Instrumented Cylindrical Inclusion. Tech. Report No. MRD 1-70, Missouri River Division, Corps of Engineers, Omaha, Nebraska.Google Scholar
  8. Berry, D. S., Fairhurst, C. (1966): Influence of Rock Anisotropy and Time Dependent Deformation on the Stress Relief and High Modulus Inclusion Techniques of in situ Stress Determination. In: Testing Techniques for Rock Mechanics, ASTM, STP. 402, Am. Soc. Testing Mats., pp. 190–206.Google Scholar
  9. Blackwood, R. L. (1977): An Instrument to Measure the Complete Stress Field in Soft Rock or Coal in a Single Operation. Proc. Int. Symp. on Field Measurements in Rock Mechanics, Kovari, K. (ed.), Vol. 1, pp. 137–150, Zurich.Google Scholar
  10. Blackwood, R. L. (1982): A Three-Dimensional Study of an Overcored Solid Inclusion Stress Instrument by the Boundary Integral Equation Method. Proc. 4th Int. Conf. in Australia on Finite Element Methods., pp. 109–113.Google Scholar
  11. Duncan Fama, M. E. (1979): Analysis of a Solid Inclusion in situ Stress Measuring Device. Proc. 4th Cong. ISRM (Montreux), Vol. 2, pp. 113–120.Google Scholar
  12. Duncan Fama, M. E., Pender, M. J. (1980): Analysis of the Hollow Inclusion Method for Measuring in situ Rock Stress. Int. J. Rock Mech. Min. Sci.17 (No. 3), 137–146.Google Scholar
  13. Hirashima, K., Koga, A. (1977): Determination of Stresses in Anisotropic Elastic Medium Unaffected by Boreholes from Measured Strains or Deformations. Proc. Int. Symp. on Field Measurements in Rock Mechanics, Kovari, K. (ed.), Vol. 1, pp. 173–182.Google Scholar
  14. Leeman, E. R., Hayes, D. J. (1966): A Technique for Determining the Complete State of Stress in Rock Using a Single Borehole, Proc. 1st. Cong. ISRM (Lisbon), Vol. II, pp. 17–24.Google Scholar
  15. Merrill, R. H. (1967): Three Component Borehole Deformation Gage for Determining the Stress in Rock. U. S. Bureau of Mines, RI 7015.Google Scholar
  16. Niwa, Y., Hirashima, K. (1971): The Theory of the Determination of Stress in an Anisotropic Elastic Medium Using an Instrumented Cylindrical Inclusion. Memoirs of the Faculty of Eng., Kyoto Univ., Japan, Vol. 33, pp. 221–232.Google Scholar
  17. Pickering, D. J. (1970): Anisotropic Elastic Parameters for Soils. Geotechnique20 (No. 3), 271–276.Google Scholar
  18. Rocha, M., Silverio, A. (1969): A New Method for the Complete Determination of the State of Stress in Rock Masses. Geotechnique19 (No. 1), 116–132.Google Scholar
  19. Rocha, M., Silverio, A., Pedro, J. O., Delgado, J. S. (1974): A New Development of the LNEC Stress Tensor Gauge. Proc. 3rd Cong. ISRM (Denver), Vol. IIA, pp. 464–467.Google Scholar
  20. Worotnicki, G., Walton, R. J. (1976): Triaxial Hollow Inclusion Gauges for the Determination of Rock Stress in situ. Proc. ISRM Symp. on Investigation of Stress in Rock and Advances in Stress Measurement. Supplement, pp. 1–8, Sydney.Google Scholar

Copyright information

© Springer-Verlag 1985

Authors and Affiliations

  • Bernard Amadei
    • 1
  1. 1.University of ColoradoBoulderUSA

Personalised recommendations