00000nam 2200000za 4500 9.840844 CaOODSP 20221107151937 cr ||||||||||| 170801s1972 oncd ob f000 0 eng d CaOODSP eng eng fre ger n-cn--- M38-8/110E-PDF M38-8/110 Gray, W. M. Stress determination from strain relief measurement on the ends of boreholes [electronic resource] : planning, data evaluation and error assessment / W.M. Gray and K. Barron, Mining Research Centre. Ottawa : Information Canada, 1972. 10, [8] p. : charts Reprint series ; RS 110 Cover title. "Reprinted from Proceedings of the International Symposium on the Determination of Stresses in Rock Masses, Lisbon, 19-21 May 1969, pp. 183-199 [...]." Historical publication digitized from print 2017 [by Natural Resources Canada]. Includes bibliographical references. "The method of strain-relief measurement on the flattened ends of boreholes is a relatively economical means for determining stress deep in rock. Experience with the method has enabled the mechanical and statistical problems of instrument design, planning the measurement system, evaluating the results and assessing the errors to be better appreciated. Use of a four-element 45-degree strain-gauge rosette is recommended. Borehole configurations for optimum precision with this and other rosette designs are given. Since it may be impractical to use an optimum configuration at a given site, a series of layouts suitable for a variety of sites is presented. An order of preference is given. Experimental methods of checking the validity of strain measurements and a statistical method for final screening of data are given. Currently, the greatest errors in the method are caused by uncertainty about the values of the calibration factors or stress concentration factors associated with flat ended boreholes. A review of recent work on this problem has yielded recommended calibration factors, with their degree of uncertainty. The sensitivity of the calculated stress components to the values of the calibration factors is illustrated by an example"--Summary, p. 1. Includes parallel titles and summaries in French and German. gccst Mining industry gccst Rocks Barron, K. Canada. Natural Resources Canada. Canada. Department of Energy, Mines and Resources. Canada. Mines Branch. Reprint series - Dept. of Energy, Mines and Resources, Mines Branch ; RS 110 (CaOODSP)9.834843 PDF 2.42 MB https://publications.gc.ca/collections/collection_2017/rncan-nrcan/M38-8/M38-8-110-eng.pdf 300189