Hoek-Brown failure criterion is an empirical correlation based on experimental data from hundreds of triaxial tests on different types of rock. It is more commonly used than the Mohr-Coulomb failure criteria as the latter doesn't provide accurate estimations of tensile strength. This video explains how to use a special case of Hoek-Brown criteria when it is applied to intact samples (i.e., rock specimens used in triaxial tests). The generalized Hoek-Brown failure criteria can be also applied to estimate the strength characteristics of jointed rock mass (this will be discussed in a separate video).
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