Discrete Element Analysis of the Response of Granular Materials During Cyclic Loading

O’Sullivan, Catherine; Cui, Liang; O'neill, Stuart C.

doi:10.3208/sandf.48.511

Cited by 84 publications

(38 citation statements)

References 20 publications

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“…However, in recent studies more emphasis has been placed on the micro-mechanical aspects of the behavior of granular materials under different loading conditions. As an example, O'Sullivan et al [10] proposed the discrete element method for modeling a drained triaxial test with circumferential periodic boundaries. They studied the responses of granular materials during drained cyclic loading by analyzing the microstructure of the assembly with microstructural descriptors, including the deviatoric fabric tensor, coordination number and distribution of the contact forces.…”

Section: Introductionmentioning

confidence: 99%

Three dimensional discrete element modeling of granular media under cyclic constant volume loading: A micromechanical perspective

Soroush

Ferdowsi

2011

Powder Technology

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Section: Introductionmentioning

confidence: 99%

Three dimensional discrete element modeling of granular media under cyclic constant volume loading: A micromechanical perspective

Soroush

Ferdowsi

2011

Powder Technology

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“…The distinct element modelling (DEM) was originally proposed by Cundall and Strack [7] and is widely applied to examine the mechanical response of granular assemblies. The DEM technique is often used to simulate the discrete nature of ballast aggregates, which consist of irregularly shaped particles subjected to static and dynamic loadings [20,38,45,50,53,67]. Particle displacements are calculated using the Newton's second law while the interaction among aggregates is determined using contact laws.…”

Section: Discrete Element Methods (Dem)mentioning

confidence: 99%

Application of geoinclusions for sustainable rail infrastructure under increased axle loads and higher speeds

Indraratna

Ferreira

et al. 2018

Innov. Infrastruct. Solut.

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Ngoc Trung, "Application of geoinclusions for sustainable rail infrastructure under increased axle loads and higher speeds" (2018). Faculty of Engineering and Information Sciences -Papers: Part B. 1988. Abstract AbstractGiven the ongoing demand for faster trains for carrying heavier loads, conventional ballasted railroads require considerable upgrading in order to cope with the increasing traffic-induced stresses. During train operations, ballast deteriorates due to progressive breakage and fouling caused by the infiltration of fine particles from the surface or mud-pumping from the underneath layers (e.g. sub-ballast, sub-grade), which decreases the load bearing capacity, impedes drainage and increases the deformation of ballasted tracks. Suitable ground improvement techniques involving geosynthetics and resilient rubber sheets are commonly employed to enhance the stability and longevity of rail tracks. This keynote paper focuses mainly on research projects undertaken at the University of Wollongong to improve track performance by emphasising the main research outcomes and their practical implications. Results from laboratory tests, computational modelling and field trials have shown that track behaviour can be significantly improved by the use of geosynthetics, energy-absorbing rubber mats, rubber crumbs and infilled-recycled tyres. Fullscale monitoring of instrumented track sections supported by rail industry (ARTC) has been performed, and the obtained field data for in situ stresses and deformations could verify the track performance, apart from validating the numerical simulations. The research outcomes provide promising approaches that can be incorporated into current track design practices to cater for high-speed freight trains carrying heavier loads.

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“…The discrete element method (DEM) introduced by Cundall and Strack (1979) is widely used to study the behaviour of granular materials. DEM is often used to model ballast because it captures the discrete nature of a granular assembly which consists of a collection of arbitrarily shaped discrete particles under quasi-static and dynamic conditions (McDowell and Bolton 1998;Lobo-Guerrero and Vallejo 2006;O'Sullivan, Cui, and O'Neill 2008;McDowell and Li 2016;Rujikiatkamjorn 2016, 2017a). Particle motion is determined using Newton's second law and the interaction between particles is determined using Newton's second law contact laws.…”

Section: Discrete Element Methods (Dem)mentioning

confidence: 99%

Current research into ballasted rail tracks: model tests and their practical implications

Indraratna

Sun

Ngo

et al. 2017

Australian Journal of Structural Engineering

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Ballasted rail tracks are the most important mode of transportation in terms of traffic tonnage serving the needs of bulk freight and passenger movement, but under train loads, the particles degrade due to breakage and the progressive accumulation of external fines or mud-pumping under the subgrade, all of which reduce its shear strength and increase track instability. These actions adversely affect the safety, passenger comfort and efficiency of tracks, as well as enforcing speed restrictions and more frequent track maintenance. In spite of advances in rail track geotechnology, the optimum choice of ballast for track design is still considered critical because ballast degradation is influenced by the amplitude and number of load cycles, particle gradation, track confining pressure and the angularity and fracture strength of individual grains. One of the most effective methods of enhancing track stability and reducing the stresses transmitted to a soft subgrade layer is to increase the stiffness of the overlying granular media. This paper presents our current knowledge of rail track geomechanics, including important concepts/topics related to laboratory testing and computational modelling approaches used to study the load-deformation behaviour of ballast improved with waste tyres, synthetic geogrids and geocells.Abstract: Transport infrastructure must now perform over the long term because heavy haul transport networks are expected to withstand higher speeds and heavier axle loads. Ballasted rail tracks are the most important mode of transportation in terms of traffic tonnage serving the needs of bulk freight and passenger movement, but under train loads the particles degrade due to breakage and the progressive accumulation of external fines or mud-pumping under the subgrade, all of which reduces its shear strength and increases track instability. These actions adversely affect the safety, passenger comfort and efficiency of tracks, as well as enforcing speed restrictions and more frequent track maintenance. In spite of advances in rail track geotechnology, the optimum choice of ballast for track design is still considered critical because ballast degradation is influenced by the amplitude and number of load cycles, particle gradation, track confining pressure, and the angularity and fracture strength of individual grains. One of the most effective methods of enhancing track stability and reducing the stresses transmitted to a soft subgrade layer is to increase the stiffness of the overlying granular media. The Centre for Geomechanics and Railway Engineering (CGRE) has developed new design and construction concepts for track upgrading by applying theory to practice to enhance track longevity and minimise the maintenance costs. Research conducted at CGRE has shown that understanding the load transfer mechanisms and their effect on ballast breakage are important pre-requisites for decreasing track maintenance costs. This paper presents our current knowledge of rail track geomechanics, including important concepts/t...

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Discrete Element Analysis of the Response of Granular Materials During Cyclic Loading

Cited by 84 publications

References 20 publications

Three dimensional discrete element modeling of granular media under cyclic constant volume loading: A micromechanical perspective

Three dimensional discrete element modeling of granular media under cyclic constant volume loading: A micromechanical perspective

Application of geoinclusions for sustainable rail infrastructure under increased axle loads and higher speeds

Current research into ballasted rail tracks: model tests and their practical implications

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