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On investigation of contact models in DEM simulation of rockfalls

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On investigation of contact models in DEM simulation of rockfalls

Nejati, Houshin (2008) On investigation of contact models in DEM simulation of rockfalls. Masters thesis, Concordia University.

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Abstract

Simulation of rockfall allows us to protect infrastructures and forests along rock slopes against the impacts of rockfall. In this thesis, a computer program based on 3D Discrete Element Method (DEM) is developed by the author for rockfall simulation and fundamental investigation of physics of a rockfall event. Each rock is modeled as a sphere and impact surfaces are generated by numbers of 3D triangles. Contacts in DEM between objects are modeled using a mass-damper model. Different contact models of DEM produce different contact stiffnesses for springs and therefore different contact forces. Since contact forces have essential effect on dynamic behaviour of particles; hence a comparative study is performed to investigate the effect of each contact model on dynamic of rocks contacts. The five chosen contact models are: linear model, Hertz-Mindlin, Ng model, elastic-inelastic power function model and combination of Hertz model and Ng model (Hertz-Ng model). Energy in linear, Hertz-Mindlin, Hertz-Ng and Ng model is dissipated using linear normal and shear dashpots. Also, the coefficient of restitution is a concept that defines the energy level of a rock after contact with a surface. To relate the concept of coefficient of restitution and damping ratio for each contact model, the correlations of damping ratio and coefficient of restitution are determined for contact of a spherical rock and horizontal wall as well as the correlation of coefficient of restitution and damping ratio for sloped walls for linear contact model. An has developed a 2D elastic-inelastic power function for modeling of normal contact of rocks and surfaces. In this research, 3D modeling of this contact model is produced, and the effects of the input parameters on dynamic behaviours of a rock are studied and the correlation between transition force and coefficient of restitution is determined. Finally, for a 3D slope, a sensitivity analysis is performed and the effect of seven input parameters on horizontal travel distance of a rock is investigated. [ Show less ] You have requested "on-the-fly" machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Show full disclaimer Neither ProQuest nor its licensors make any representations or warranties with respect to the translations. The translations are automatically generated "AS IS" and "AS AVAILABLE" and are not retained in our systems. PROQUEST AND ITS LICENSORS SPECIFICALLY DISCLAIM ANY AND ALL EXPRESS OR IMPLIED WARRANTIES, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES FOR AVAILABILITY, ACCURACY, TIMELINESS, COMPLETENESS, NON-INFRINGMENT, MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Your use of the translations is subject to all use restrictions contained in your Electronic Products License Agreement and by using the translation functionality you agree to forgo any and all claims against ProQuest or its licensors for your use of the translation functionality and any output derived there from. Hide full disclaimer Translations powered by LEC.

Divisions:Concordia University > Gina Cody School of Engineering and Computer Science > Building, Civil and Environmental Engineering
Item Type:Thesis (Masters)
Authors:Nejati, Houshin
Pagination:xvi, 163 leaves : ill. ; 29 cm.
Institution:Concordia University
Degree Name:M. A.Sc.
Program:Building, Civil and Environmental Engineering
Date:2008
Thesis Supervisor(s):Zsaki, A
ID Code:976751
Deposited By: Concordia University Library
Deposited On:22 Jan 2013 16:32
Last Modified:18 Jan 2018 17:43
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