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Published April 1986 | Published
Journal Article Open

Holographic in situ stress measurements

Abstract

A new instrument for measuring the in situ level of stress in boreholes has been developed. The instrument operates on the principle of locally relieving the stresses acting on a rock mass by drilling a small hole into the borehole surface and recording the resultant displacement field by holographic interferometry. Because the recording technique is optical, the entire displacement field due to stress relief is obtained. A description of the stressmeter, theory of the interferometric technique, data reduction methodology, and results of laboratory stress relief calibration tests are presented. In addition, we present results from a field deployment of the instrument in an underground shale mine in Garfield County, Colorado using a test borehole within a support pillar. Sufficient data were obtained to constrain five of six stress components at a shallow level of the test borehole, thereby demonstrating the viability of the holographic technique. The holographic stress-relief data yield an approximate EW maximum horizontal stress direction. By comparison with previous hydrofracture measurements of Bredehoeft et al., our results indicate substantial stress-relief near the pillar face, thus masking any relicts of the far-field tectonic stress.

Additional Information

Copyright © 1986 The Royal Astronomical Society. Accepted 1985 August 14. Received 1985 August 14; in original form 1984 August 26. We thank J. Schmidt, D. Tomren, D. Evensen, P. Bhuta and S. N. Cohn for their efforts in the design of earlier versions of the holographic stressmeter. Numerous components of the instrument were designed in collaboration with B. Barber, W. Ginn and W. Miller. C. Hudson, R. Wickes and B. Barber fabricated and repaired innumerable parts with a great deal of skill and a surprising amount of cheer. Discussions with R. Wuerker, L. Heflinger, B. Hager, T. Webb, A. S. Nieto and A. Frankel were of immense value and are greatly appreciated as is the careful review of T. Engelder. We gratefully acknowledge support of this research by the US Department of Energy, Contract number DE-AT03-83ER13120, and gifts from Schlumberger Technology Corporation and Sun Oil Company. Contribution 4121 of the Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California.

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August 22, 2023
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October 18, 2023