Micro-mechanical analysis on the onset of erosion in granular materials

Abstract

The onset of internal erosion is a particle level phenomenon, and therefore, a numerical model capable of tracking the behaviour of particles at micro-scale is needed to exemplify most of the critical variables involved in the process. In this paper, a three-dimensional fully coupled fluid–solid model was utilized to explore the initiation of erosion. Particles were modelled on a micro-scale using the discrete element method (DEM), while the fluid was modelled at a meso-scale using the lattice Boltzmann method (LBM). Fluid was passed through a solid matrix in an opposing direction to gravity with the pore water pressure controlled in stepwise stages until internal erosion or bulk movement of the particles developed and progressed. The model was validated through experimental results found in the literature. Once validated, particle fluid properties were analyzed for the onset of erosion. Determination of a critical hydraulic gradient was obtained from the modelled scenario, which gave clear evidence that the coupled DEM-LBM scheme is a very effective tool for studying internal erosion phenomena in water retaining structures.

Keywords:

• piping erosion
• lattice Boltzmann method (LBM)
• discrete element method (DEM)
• critical hydraulic gradient

Acknowledgements

The authors would like to acknowledge the Geotechnical Engineering Centre at The University of Queensland for developing MechSys open source library (http://mechsys.nongnu.org) and the Macondo cluster, hosted by the School of Civil Engineering at The University of Queensland.

Notes

No potential conflict of interest was reported by the authors.

Additional information

Funding

The presented research is part of the Discovery Project [DP120102188], Hydraulic erosion of granular structures: Experiments and computational simulations, funded by the Australian Research Council.