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

摘要

This study aims to investigate the strength anisotropy associated with discontinuity orientation byperforming block punch index (BPI) tests and uniaxial compressive strength (UCS) tests, and to developsome empirical relationships for estimating the BPI and UCS in the strongest direction, and the UCSfrom the BPI determined at any angle between the loading direction and weakness plane. Theexperimental results obtained from six rock types show that these rocks fall into the moderate-to-lowstrength anisotropy classes. The comparison between the observed and predicted UCS values indicatedthat the prediction performances of the equations developed are quite good. Numerical simulationsrevealed that numerically estimated BPI values are very close to experimentally determined values foreach angle between the loading direction and the weakness planes involved by the BPI specimens. Asthe angle between the weakness planes and loading increases, plastic zones become wider andunsymmetrical. The results of this study are also applicable to anisotropic rocks outside the strengthranges of the rocks studied by the authors, but their degree of anisotropy should be in the range oflow-to-moderate.