Discrete modelling of front propagation in backward piping erosion

¹ University of Lyon, LTDS - CNRS UMR 5513, Ecole Centrale de Lyon, 36 avenue Guy de Collongue, Ecully 69134 Cedex, France
² University Savoie Mont - Blanc, LOCIE - CNRS UMR 5271, Campus Universitaire - Savoie Technolac, 73376 Le Bourget du Lac Cedex, France
³ University of Molise/DiBT, Via Francesco De Sanctis, 1, 86100 Campobasso, Italy

^* e-mail: francesco.froiio@ec-lyon.fr

Published online: 30 June 2017

Abstract

A preliminary discrete numerical model of a REV at the front region of an erosion pipe in a cohesive granular soil is briefly presented. The results reported herein refer to a simulation carried out by coupling the Discrete Element Method (DEM) with the Lattice Boltzmann Method (LBM) for the representation of the granular and fluid phases, respectively. The numerical specimen, consisiting of bonded grains, is tested under fully-saturated conditions and increasing pressure difference between the inlet (confined) and the outlet (unconfined) flow regions. The key role of compression arches of force chains that transversely cross the sample and carry most part of the hydrodynamic actions is pointed out. These arches partition the REV into an upstream region that remains almost intact and a downstream region that gradually degrades and is subsequently eroded in the form of a cluster. Eventually, the collapse of the compression arches causes the upstream region to be also eroded, abruptly, as a whole. A complete presentation of the numerical model and of the results of the simulation can be found in [12].