DEM analysis of the influence of the intermediate stress ratio on the critical-state behaviour of granular materials

X. Huang, K. J. Hanley, C. O'Sullivan*, C. Y. Kwok, M. A. Wadee

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

The critical-state response of granular assemblies composed of elastic spheres under generalised three-dimensional loading conditions was investigated using the discrete element method (DEM). Simulations were performed with a simplified Hertz-Mindlin contact model using a modified version of the LAMMPS code. Initially isotropic samples were subjected to three-dimensional stress paths controlled by the intermediate stress ratio, b. Three types of simulation were performed: drained (with b-value specified), constant volume and constant mean effective stress. In contrast to previous DEM observations, the position of the critical state line is shown to depend on b. The data also show that, upon shearing, the dilatancy post-peak increases with increasing b, so that at a given mean effective stress, the void ratio at the critical state increases systematically with b. Four commonly-used three-dimensional failure criteria are shown to give a better match to the simulation data at the critical state than at the peak state. While the void ratio at critical state is shown to vary with b, the coordination number showed no dependency on b. The variation in critical state void ratios at the same value is apparently related to the directional fabric anisotropy which is clearly sensitive to b.

Original languageEnglish
Pages (from-to)641-655
Number of pages15
JournalGranular Matter
Issue number5
Publication statusPublished - Oct 2014
Externally publishedYes

Keywords / Materials (for Non-textual outputs)

  • Discrete element method
  • Critical state
  • Intermediate stress ratio
  • Buckling
  • Failure criteria


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