Quantitative analysis of piping erosion micro-mechanisms with coupled CFD and DEM method

Hui Tao, Junliang Tao

Research output: Contribution to journalArticle

27 Scopus citations

Abstract

Piping, as one of the critical patterns of internal erosion, has been reported as a major cause for failures of embankment dams and levees. The fundamental mechanism of piping was traditionally investigated through experimental trials and simplified theoretical methods in macroscale. Nevertheless, the initiation and progressive evolution of piping is a microscale phenomenon in its essence. The current understanding of the micro-mechanism of piping erosion is limited due to a lack of quantitative analysis and visualized evidence. And in fact, seepage flows can affect the soil fabrics and the development of contact forces between particles. But how these fabrics and contact forces evolve under a critical hydraulic gradient is still not fully understood. In this paper, the detailed process of piping erosion is investigated by using a coupled computational fluid dynamics and discrete element method (CFD–DEM) approach. The treatment of soil–flow interactions in CFD–DEM is explained by exchanging the momentum between the two phases. During the simulation, the piping erosion process is initiated by incrementally ascending differential water head across the soil samples. The three main stages of piping erosion (initial movement, continuation of erosion and total heave) can be identified from monitoring the particle velocity and positions. In addition, the evolution of contact force, hydraulic force, coordination number and void fraction is inspected to provide insight into the micro-mechanism of piping erosion. Two cases are simulated, one with a uniform particle size and a relatively uniform porosity distribution and the other with specific particle size and porosity distributions. An interesting finding from this study is that piping does not always initiate from the free surface and the evolution of piping depends heavily on the particle size and porosity distribution.

Original languageEnglish (US)
Pages (from-to)573-592
Number of pages20
JournalActa Geotechnica
Volume12
Issue number3
DOIs
StatePublished - Jun 1 2017
Externally publishedYes

Keywords

  • Computational fluid dynamics
  • Contact force
  • Discrete element method
  • Interaction force
  • Internal erosion
  • Micro-mechanism
  • Piping

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology
  • Earth and Planetary Sciences (miscellaneous)

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