SYMPOSIA PAPER Published: 01 January 1966

Laboratory Testing of Rock Strength


New equipment and testing techniques have been developed to investigate the basic strength of rock. The effect of varying the intermediate principal stress on the strength appears appreciable in the case of crystalline rocks such as granite. Failure of hollow cylinders of rock under conditions of high ratios of the intermediate to the major principal stress appears to be initiated as a “spalling” failure. Although simple tests for the determination of the strength of intact rock can furnish reliable data for certain design situations, the behavior of discontinuous rock masses must be evaluated by means of suitable model studies and analytical procedures. While the results will still be only approximations of the mass properties, there are definite benefits in terms of planning and interpreting field tests.

Author Information

Mazanti, B, B
Georgia Institute of Technology, Atlanta, Ga.
Sowers, G, F
Georgia Institute of Technology and vice president, Law Engineering Testing Co., Atlanta, Ga.
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Developed by Committee: D18
Pages: 207–231
DOI: 10.1520/STP45143S
ISBN-EB: 978-0-8031-6016-3
ISBN-13: 978-0-8031-6170-2