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Lookup NU author(s): Professor Stefano Utili
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
This paper presents a numerical investigation of the behaviour of dry granular flows generated by the collapse ofprismatic columns via 3D Distinct Element Method (DEM) simulations in plane strain conditions. Firstly, bymeans of dimensional analysis, the governing parameters of the problem are identified, and variables areclustered into dimensionless independent and dependent groups.Secondly, the results of the DEMsimulations are illustrated. Different regimes of granularmotion were observeddepending on the initial column aspect ratio. The profiles observed at different times for columns of variousaspect ratios show to be in good agreement with available experimental results.Thirdly, a detailed analysis of the way energy is dissipated by the granular flows was performed. It emerges thatmost of the energy of the columns is dissipated by inter-particle friction, with frictional dissipation increasingwith the column aspect ratio. Also, the translational and rotational components of the kinetic energy of theflows, associated to particle rotational and translational motions respectively, were monitored during therun-out process. It is found that the rotational component is negligible in comparison with the translationalone; hence in order to calculate the destructive power of a granular flowslide, only the translational contributionof the kinetic energy is relevant.Finally, a methodology is presented to calculate the flux of kinetic energy over time carried by the granular flowthrough any vertical section of interest. This can be related to the energy released by landslide induced granularflows impacting against engineering structures under the simplifying assumption of neglecting all structure-flowinteractions. This represents the first step towards achieving a computational tool quantitatively predicting thedestructive power of a given flowat any location of interest along its path. This can be useful for the design of engineeringworks for natural hazard mitigation. To this end, also the distribution of the linear momentum of theflow over depthwas calculated. It emerges that the distribution is initially bilinear, due to the presence of an uppermostlayer of particles in an agitated loose state, but after some time becomes linear.This type of analysis showcases the potential of the Distinct Element Method to investigate the phenomenologyof dry granular flows and to gather unique information currently unachievable by experimentation.
Author(s): Utili S, Zhao T, Houlsby GT
Publication type: Article
Publication status: Published
Journal: Engineering Geology
Print publication date: 24/02/2015
Online publication date: 03/09/2014
Acceptance date: 22/08/2014
Date deposited: 23/03/2017
ISSN (print): 0013-7952
ISSN (electronic): 1872-6917
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