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Downhole Rock Borehole Shear Tester.
Handy-RL; Roorda-B; Futrell-S
For Reference Only At Bureau Libraries :22 pages
The goal of this research was to adapt the rock borehole shear test for use in deep, small-diameter boreholes. Operating somewhat on the principle of a rock bolt, the borehole shear test measures both the expansion pressure and pulling force to give discrete measures of rock shearing strength as a function of the applied normal pressure. A new instrument was designed and built to fit into a 2- 3/8-in-diam hole. Complications attributed to constraints of the small hole, the added requirements of an in-hole anchor to push against, and a rotating shear plate cleaner for repeated tests downhole made the design unreliable. One reason for the complexity could be the length, which is over 10 feet. The instrument also employs concentric cylinders and one hydraulic cylinder bored into the piston of another, or it would be even longer. Since advanced drilling technology has greatly reduced costs of drilling 5- or 6-in- diam holes, the downhole tester should be redesigned and simplified for use in a larger diameter drill hole.
CP; Final Contract Report;
For Reference Only At Bureau Libraries
Iowa State University, Ames
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division