The failure envelope of a bonded particle model for rock in three-dimensional stress space



Schöpfer, M.P.J., Childs, C. & Manzocchi, T.

Abstract - The complete yield, failure and residual strength envelope of a bonded particle model (BPM) for rock is determined under constant mean stress and Lode angle loading condi-tions. These loading paths are achieved using distortional periodic space. The model results illustrate that the emergent strengths depend on the intermediate principal stress and therefore suggest that the commonly used Mohr-Coulomb and Hoek-Brown failure criteria are an over-simplification. Moreover, two invariant failure criteria, such as Drucker-Prager, are also incapable of describing the intermediate principal stress dependence of strength. Therefore a generalized failure criterion that depends on all three stress invariants is used to represent the BPM strength envelopes in three-dimensional stress space. The stress strain behavior of these BPMs also illustrates that at high mean stress no significant stress drop occurs after peak. The transition pressure at which no loss in strength occurs is a mean stress and Lode angle dependent space curve.


In: Continuum and Distinct Element Numerical Modeling in Geomechanics. (Edited by Zhu, Detournay, Hart & Nelson), Itasca International, Minneapolis, ISBN 978-0-9767577-3-3, 2013.