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In Situ Strain Orientations: A Comparison of Three Measuring Techniques.
NTIS: PB 205 502 :17 pages
Photoelastic, wire resistance, and borehole-deformation gages were used to measure the in situ strains when an outcropping Black Hand Sandstone Formation in Hocking State Forest, Hocking County, Ohio, was overcored to stress-relieve the surrounding sandstone. Strains transmitted to the photoelastic gage did not produce isochromatic patterns suitable for quantitative analysis. Strain readings from the wire resistance gage indicated tensile-strain loading during overcoring; readings from the strain-gage bridges in the borehole- deformation gage indicated compressive-strain relaxation during overcoring. The magnitude and orientation of the computed stress fields obtained from both gages were comparable when the corresponding tensile and compressive elastic moduli were applied. Measurements of in situ strain in sandstone were shown to have promise but to require further development in field technique that could likely be achieved through experience.
IH; Report of Investigation;
NTIS Accession No.
NTIS: PB 205 502
Page last reviewed: April 12, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division