Discrete element modelling of scaled railway ballast under triaxial conditions

McDowell, G. R.; Li, Huiqi

doi:10.1007/s10035-016-0663-8

Cited by 80 publications

(33 citation statements)

References 32 publications

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“…A few methods to generate complex shapes of ballast particle were later proposed [14][15][16][17]. With the use of irregular shapes, the shear strength of ballast particles has been successfully modelled by triaxial simulations [18][19][20][21]. The improvement of using geogrid-reinforced ballast has also been successfully [22][23][24][25] by representing the geogrid as a group of bonded spheres, which is similar to the generation method for the USP in this study.…”

Section: Introductionmentioning

confidence: 74%

Discrete element modelling of under sleeper pads using a box test

McDowell

2018

Granular Matter

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It has recently been reported that under sleeper pads (USPs) could improve ballasted rail track by decreasing the sleeper settlement and reducing particle breakage. In order to find out what happens at the particle-pad interface, discrete element modelling (DEM) is used to provide micro mechanical insight. The same positive effects of USP are found in the DEM simulations. The evidence provided by DEM shows that application of a USP allows more particles to be in contact with the pad, and causes these particles to transfer a larger lateral load to the adjacent ballast but a smaller vertical load beneath the sleeper. This could be used to explain why the USP helps to reduce the track settlement. In terms of particle breakage, it is found that most breakage occurs at the particle-sleeper interface and along the main contact force chains between particles under the sleeper. The use of USPs could effectively reduce particle abrasion that occurs in both of these regions.

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Section: Introductionmentioning

confidence: 74%

Discrete element modelling of under sleeper pads using a box test

McDowell

2018

Granular Matter

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“…Each research group worked independently to model the behaviour of a scaled ballast with reference to the same laboratory data [3]. The work at Nottingham, in a paper [21] submitted for review simultaneously with this one, models particle abrasion via the breakage of small asperities.…”

Section: Acknowledgmentsmentioning

confidence: 99%

Discrete element simulation of railway ballast: modelling cell pressure effects in triaxial tests

et al. 2016

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The paper investigates reproducing the effects of confining pressure on the behaviour of scaled railway ballast in triaxial tests in discrete element models (DEM). Previous DEM work, using a standard Hertzian elastic contact law with an elastic-perfectly plastic tangential slip model, has been unable to replicate the behaviour observed in laboratory tests across a range of confining pressures without altering both the material stiffness and the inter-particle friction. A new contact law modelling damage at the contacts between particles is introduced. Particle contact is via sphericallycapped conical asperities, which reduce in height if overstressed. This introduces plasticity to the behaviour normal to the contact surface. In addition, the inter-particle friction angle is varied as a function of normalized contact normal force. At relatively low normal forces the friction angle must be increased for peak mobilized friction angles to match the laboratory data, an effect that is attributed to interlocking at the scale of surface roughness. Simulation results show close agreement with laboratory data.

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“…Past studies have been carried out to investigate the effects of the loading characteristics (i.e. monotonic or cyclic loads) on the shear stress-strain responses of railway ballast (Lackenby et al 2007;Sun et al 2018;McDowell and Li 2016, Powrie et al 2007, Biabani et al 2016. Based on an extensive laboratory testing program, the volumetric strains of ballast under monotonic and cyclic loading conditions and at different confining pressures have been evaluated, as shown in Figure 1.…”

Section: Behavior Of Ballast Subjected To Monotonic and Cyclic Loadingsmentioning

confidence: 99%

Advancement of Rail Ballast Testing Methodologies and Design Implications

Indraratna¹,

Ngo²,

Rujikiatkamjorn³

et al. 2020

Geo-Congress 2020

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Given the limited capacity of available railway tracks in Australia to sustain increasingly faster and heavier trains, the development of innovative and sustainable ballasted tracks is essential for Australian transport infrastructure. Upon repeated train loading, ballast aggregates become degraded and fouled owing to the intrusion of external fines either from the subbase or surface, which decreases track drainage potentially leading to track instability. This paper reviews some advancements in testing methodologies and design implications of ballasted tracks stabilized with artificial inclusions, including geocomposites, energy absorbing rubber mats and end-of-life tires. Measured test data shows that the use of these waste rubber products and geosynthetics provides an appropriate solution for mitigating unacceptable track degradation and for improving sustainable track alignment, apart from reducing the thickness of the ballast layer. Field monitoring data from fully instrumented tracks constructed at Singleton, Australia is presented and discussed. The outcomes of this study contribute to a better understanding of the performance of reinforced ballasted tracks, which will be imperative for the development of more efficient and cost-effective track designs with enhanced safety and passenger comfort. ABSTRACTGiven the limited capacity of available railway tracks in Australia to sustain increasingly faster and heavier trains, the development of innovative and sustainable ballasted tracks is essential for Australian transport infrastructure. Upon repeated train loading, ballast aggregates become degraded and fouled owing to the intrusion of external fines either from the subbase or surface, which decreases track drainage potentially leading to track instability. This paper reviews some advancements in testing methodologies and design implications of ballasted tracks stabilized with artificial inclusions, including geocomposites, energy absorbing rubber mats and end-of-life tires. Measured test data shows that the use of these waste rubber products and geosynthetics provides an appropriate solution for mitigating unacceptable track degradation and for improving sustainable track alignment, apart from reducing the thickness of the ballast layer. Field monitoring data from fully instrumented tracks constructed at Singleton, Australia is presented and discussed. The outcomes of this study contribute to a better understanding of the performance of reinforced ballasted tracks, which will be imperative for the development of more efficient and cost-effective track designs with enhanced safety and passenger comfort.

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Discrete element modelling of scaled railway ballast under triaxial conditions

Cited by 80 publications

References 32 publications

Discrete element modelling of under sleeper pads using a box test

Discrete element modelling of under sleeper pads using a box test

Discrete element simulation of railway ballast: modelling cell pressure effects in triaxial tests

Advancement of Rail Ballast Testing Methodologies and Design Implications

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