DEM simulation of the behaviour of geogrid stabilised ballast fouled with coal |
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| Institution: | 1. Department of Civil and Environmental Engineering, Indian Institute of Technology Patna, Patna 800 013, Bihar, India;2. Centre for Geomechanics and Railway Engineering, University of Wollongong, Wollongong City, NSW 2522, Australia;1. Civil Engineering, Univ. of Wollongong, Wollongong, NSW 2522, Australia;2. Centre for Geomechanics and Railway Engineering, Univ. of Wollongong, Wollongong, NSW 2522, Australia;3. ARC Centre of Excellence for Geotechnical Science and Engineering, Univ. of Wollongong, Wollongong, NSW 2522, Australia;4. Civil Engineering, City Univ. of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong Special Administrative Region;5. Department of Civil and Architectural Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong Special Administrative Region;6. Civil Engineering, Univ. of Newcastle, Newcastle, NSW 2308, Australia;7. ARC Centre of Excellence for Geotechnical Science and Engineering, Univ. of Newcastle, Newcastle, NSW 2308, Australia;1. Department of Civil and Environmental Engineering, The University of Illinois, Urbana-Champaign, Urbana, IL 61801, USA;2. Department of Civil Engineering, Boise State University, Boise, ID 83725, USA;1. Centre for Geomechanics and Railway Engineering, University of Wollongong, Wollongong City, NSW 2522, Australia;2. School of Civil, Mining and Environmental Engineering, University of Wollongong, Wollongong City, NSW 2522, Australia;3. Australian Rail Track Corporation Ltd., Broadmeadow, NSW 2292, Australia;4. School of Civil & Environmental Engineering, Centre for Built Infrastructure Research (CBIR), Faculty of Engineering & Information Technology, University of Technology Sydney City Campus, 15 Broadway, Ultimo, NSW 2007, Australia;1. Nottingham Centre for Geomechanics, Faculty of Engineering, University of Nottingham, Nottingham, NG7 2RD, UK;2. Nottingham Transportation Engineering Centre, Faculty of Engineering, University of Nottingham, Nottingham, NG7 2RD, UK;1. Centre for Geomechanics and Railway Engineering, Faculty of Engineering and Information Sciences, University of Wollongong, Wollongong City, NSW 2522, Australia;2. Nottingham Centre for Geomechanics, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK |
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| Abstract: | Geogrids are commonly used in railway construction for reinforcement and stabilisation. When railway ballast becomes fouled due to ballast breakage, infiltration of coal fines, dust and subgrade soil pumping, the reinforcement effect of geogrids decreases significantly. This paper presents results obtained from Discrete Element Method (DEM) to study the interface behaviour of coal-fouled ballast reinforced by geogrid subjected to direct shear testing. In this study, irregularly-shaped aggregates (ballast) were modelled by clumping together 10–20 spheres in appropriate sizes and positions. The geogrid was modelled by bonding a large number of small spheres together to form the desired grid geometry and apertures. Fouled ballast with 40% Void Contaminant Index (VCI) was modelled by injecting a predetermined number of miniature spheres into the voids of fresh ballast. A series of direct shear tests for fresh and fouled ballast reinforced by the geogrid subjected to normal shear stresses varying from 15 kPa to 75 kPa were then simulated in the DEM. The numerical results showed a good agreement the laboratory data, indicating that the DEM model is able to capture the behaviour of both fresh and coal-fouled ballast reinforced by the geogrid. The advantages of the proposed DEM model in terms of capturing the correct stress–displacement and volumetric behaviour of ballast, as well as the contact forces and strains developed in the geogrids are discussed. |
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| Keywords: | Ballast Geogrids Discrete element modeling |
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