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Peter Cundall award to Martin Schöpfer

Paper will be presented as a keynote address at the forthcoming FLAC/DEM Symposium in Hangzhou, China. The paper entitled ‘The failure envelope of a bonded particle model for rock in three-dimensional stress space’ by M. Schöpfer, C. Childs and T. Manzocchi, which is a summary of a paper recently published in the Journal of Geophysical Research, was selected for the Peter Cundall award. The Peter Cundall Award is presented to the best overall paper submitted for presentation at the 3rd FLAC/DEM Symposium, October 2013, Hangzhou, China.

Dr Cundall (Itasca Consulting Group) is the original author of many computer codes, including the Distinct Element Method (DEM) codes PFC2D and PFC3D, which are intensely used by the Structural Processes Group, Vienna. The award winning paper by Schöpfer and co-authors describes the strength of a rock-like numerical material, modelled as an assemblage of cemented spheres using PFC3D, in three-dimensional stress-space. The emergent yield, failure and residual strength envelopes exhibit a shape which is remarkably similar to that determined for natural rocks tested under laboratory conditions. 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 oversimplification. Moreover, two invariant failure criteria, such as Drucker-Prager, are also incapable of describing the intermediate principal stress dependence of strength.


Best-fit yield (onset of permanent strain), fracture (peak stress) and frictional sliding (residual strength) envelopes plotted in three-dimensional stress space. Peak stress data (N = 442) obtained from the DEM simulations are plotted as red spheres with a radius of 5 MPa in one sextant only.




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