This paper explores intact rock strength based on several different sets of triaxial test data gathered using automated instantaneous volumetric strain measurements to pre-empt specimen failure and determine the end of each consecutive testing stage. This allows each sample to be tested at multiple confinement stages and for the full intact rock strength curve to be determined for each sample, including the shape of the curve at small confinements. The residual intact rock shear strength was also tested in stages at the end of the tests. Such a variety of tests on one sample is not possible with single stage tests and represents an advantage of using automated multistage testing. The test results are then used to investigate the scope for optimization of the Hoek-Brown failure envelope at low confinement commensurate with open pits. In addition, the results are used to investigate the non-linearity of the intact rock failure envelope at low confinement. The paper concludes by finding that there is scope for optimization of the Hoek-Brown failure envelope at low confinement and also that the intact rock failure envelope is likely to be non-linear at low confinement.
New Contributions to Intact Rock Strength Through Automated Triaxial Testing
Venter, J., Hamman, E. C. F., and C. Purvis. "New Contributions to Intact Rock Strength Through Automated Triaxial Testing." Paper presented at the 53rd U.S. Rock Mechanics/Geomechanics Symposium, New York City, New York, June 2019.
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