Empirical models and numerical analysis for assessing strength anisotropy based on block punch index and uniaxial compression tests

Karakul H., Ulusay R., Isik N. S.

INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES, vol.47, no.4, pp.657-665, 2010 (SCI-Expanded) identifier identifier


This study aims to investigate the strength anisotropy associated with discontinuity orientation by performing block punch index (BPI) tests and uniaxial compressive strength (UCS) tests, and to develop some empirical relationships for estimating the BPI and UCS in the strongest direction, and the UCS from the BPI determined at any angle between the loading direction and weakness plane. The experimental results obtained from six rock types show that these rocks fall into the moderate-to-low strength anisotropy classes. The comparison between the observed and predicted UCS values indicated that the prediction performances of the equations developed are quite good. Numerical simulations revealed that numerically estimated BPI values are very close to experimentally determined values for each angle between the loading direction and the weakness planes involved by the BPI specimens. As the angle between the weakness planes and loading increases, plastic zones become wider and unsymmetrical. The results of this study are also applicable to anisotropic rocks outside the strength ranges of the rocks studied by the authors, but their degree of anisotropy should be in the range of low-to-moderate. (C) 2010 Elsevier Ltd. All rights reserved.