Piping flow of cohesive granular materials in silo modelled by finite element method

Q. J. Zheng, B. S. Xia, R. H. Pan, A. B. Yu

Research output: Contribution to journalArticleResearchpeer-review

10 Citations (Scopus)

Abstract

Granular materials can exhibit complex solid- and liquid-like behaviours which are not fully understood. In this work, the piping flow of cohesive granular materials in a flat-bottomed silo is investigated using finite element method (FEM). The aim is to provide a dynamic picture of the piping formation, so as to explore the variation of field variables (velocity and stress) in time and space and obtain new insights into the piping mechanism. To be illustrative and consistent with the previous studies, it is conducted under ideal, simplified conditions including constant shear cohesion and negligible dilation. And a simple cohesive-frictional model is employed for describing the granular material. The results confirm that the low flowable granular materials, represented by high shear cohesion or internal friction, are prone to piping. But some more complicated mechanisms are recognised. First, the tensile stress is important for preventing velocity discontinuities and piping in the bulk of particles. Even for the same shear cohesion, different tensile strengths can result in distinct flow behaviours. Secondly, the final stress state is history-dependent. Only small stresses are observed in the vicinity of the channel because of the high velocity therein at the flowing stage. The radial, vertical and hoop stresses also depend on the development of plasticity. Finally, a governing rule of piping is yielded based on FEM results and is shown to agree qualitatively with the Jenike theory. The need for future studies is also discussed.

Original languageEnglish
Article number2
Number of pages13
JournalGranular Matter
Volume19
Issue number2
DOIs
Publication statusPublished - 1 Feb 2017

Keywords

  • Cohesive granular materials
  • Finite element method
  • Piping flow
  • Rathole
  • Silo

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