Behavior of geogrid-reinforced ballast under various levels of fouling

Indraratna, Buddhima; Ngo, Ngoc Trung; Rujikiatkamjorn, Cholachat

doi:10.1016/j.geotexmem.2011.01.015

Cited by 148 publications

(83 citation statements)

References 19 publications

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“…Dombrow et al (2009) and Ebrahimi et al (2014) carried out large-scale tests of fouled ballast and reported that as the level of fouling increased the shear strength steadily decreased. This reduction in the shear strength of fouled ballast associated with coal and clay fouling was also observed in the laboratory by Indraratna et al (2011b) and Indraratna et al (2013b).…”

Section: Introductionsupporting

confidence: 71%

“…In the dilation zone, where a specimen was highly fouled (VCI=50%), it shows a decrease in the rate and magnitude of dilation at high axial strains ( 20 %). This observation was supported by Indraratna et al (2011b) when they demonstrated that fine particles would lubricate ballast aggregates and decrease the inter-particle friction angles, and thereby increase the plastic deformation and differential track settlement. The lubricating effect of fine particles (fouling material) coating the relatively rough surface of large aggregates can be attributed to the reduction of inter-particle friction and less interlocking of angular aggregates, causing a reduction in shear strength.…”

Section: Mobilised Friction Angle and Volumetric Change Analysismentioning

confidence: 78%

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Micromechanics-Based Investigation of Fouled Ballast Using Large-Scale Triaxial Tests and Discrete Element Modeling

Ngo

Indraratna

Rujikiatkamjorn

2017

J. Geotech. Geoenviron. Eng.

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Section: Introductionsupporting

confidence: 71%

Section: Mobilised Friction Angle and Volumetric Change Analysismentioning

confidence: 78%

Micromechanics-Based Investigation of Fouled Ballast Using Large-Scale Triaxial Tests and Discrete Element Modeling

Ngo

Indraratna

Rujikiatkamjorn

2017

J. Geotech. Geoenviron. Eng.

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“…Largescale direct shear tests for ballast and tensile tests for geogrid were carried out to determine required input parameters for DEM modelling. By calibrating with experimental results reported by Indraratna et al (2011) and Ngo et al (2014), a set of micromechanical parameters adopted for DEM simulations of ballast, geogrid, and coal fines are presented in Table 1.…”

Section: Fig 1 Particle Size Distributions Of Materials Tested Discmentioning

confidence: 99%

“…The main purposes are to distribute the train load to the underlying layers at a reduced and acceptable stress level and to provide track drainage conditions. Upon repeated train loading, ballast deteriorates and spreads laterally causing track instability (Indraratna et al 2011;Ngo et al 2014). In addition to this, due to progressive degradation and the infiltration of fine particles or mud-pumping from below layers, ballast gets fouled, which decreases the shear strength and increases the deformation of ballasted tracks (Indraratna et al 2013;Tutumluer et al 2008).…”

Section: Introductionmentioning

confidence: 99%

“…Large-scale direct shear tests for ballast reinforced by the 40 mm x 40 mm geogrid were carried out to shear to a displacement of h=37mm and detailed results discussed elsewhere by Indraratna et al (2011), while some of these data were used in this study to calibrate DEM models. Experimental data highlighted that the peak shear stress of ballast increases with an increase in normal stress and then decreases with an increase level of fouling.…”

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confidence: 99%

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Study on the Interface Behavior of a Geosynthetics-Reinforced Fouled Ballast Using the Discrete Element Method

2016

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Railways offer an efficient and economic transport mode in many parts of the developed countries including Australia, China and USA. Ballast layer is designed as a load bearing layer for rail tracks and to be free draining, but when the ballast voids are wholly or partially impeded due to the intrusion of fine particles, the ballast can be considered to be fouled. Fouling causes a reduction in the drainage capacity of ballast, thereby reducing the track resiliency and triggering high maintenance costs. Geosynthetics are commonly used in railway construction for reinforcement and stabilization purposes. When railway ballast becomes fouled the beneficial effect of the geosynthetics could decrease significantly. This paper presents a study of how the interface behavior of geosynthetics-ballast copes with fouling using discrete element modelling (DEM) of large-scale direct shear tests. A series of large-scale direct shear tests for coal fouled ballast were carried out in the laboratory and were then simulated in the DEM. Shear stress-strain and volumetric dilation responses obtained from the DEM simulations were in reasonable agreement with those measured experimentally. The contact force distributions of fresh and fouled ballast were captured and shown that the fouled ballast exhibited higher number of contact forces compared to the fresh ballast assembly. This is due to coal fines accumulated in voids among large particles then partially carry and transmit contact forces across the assembly. Strains developed horizontally across the geogrid were also analyzed in this study. ABSTRACT:Railways offer an efficient and economic transport mode in many parts of the developed countries including Australia, China and USA. Ballast layer is designed as a load bearing layer for rail tracks and to be free draining, but when the ballast voids are wholly or partially impeded due to the intrusion of fine particles, the ballast can be considered to be fouled. Fouling causes a reduction in the drainage capacity of ballast, thereby reducing the track resiliency and triggering high maintenance costs. Geosynthetics are commonly used in railway construction for reinforcement and stabilization purposes. When railway ballast becomes fouled the beneficial effect of the geosynthetics could decrease significantly. This paper presents a study of how the interface behavior of geosynthetics-ballast copes with fouling using discrete element modelling (DEM) of large-scale direct shear tests. A series of large-scale direct shear tests for coal fouled ballast were carried out in the laboratory and were then simulated in the DEM. Shear stress-strain and volumetric dilation responses obtained from the DEM simulations were in reasonable agreement with those measured experimentally. The contact force distributions of fresh and fouled ballast were captured and shown that the fouled ballast exhibited higher number of contact forces compared to the fresh ballast assembly. This is due to coal fines accumulated in voids among large particles then...

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Track Geomechanics for Future Railways: Use of Artificial Inclusions

Indraratna

Ngo

et al. 2021

Lecture Notes in Civil Engineering

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Behavior of geogrid-reinforced ballast under various levels of fouling

Cited by 148 publications

References 19 publications

Micromechanics-Based Investigation of Fouled Ballast Using Large-Scale Triaxial Tests and Discrete Element Modeling

Micromechanics-Based Investigation of Fouled Ballast Using Large-Scale Triaxial Tests and Discrete Element Modeling

Study on the Interface Behavior of a Geosynthetics-Reinforced Fouled Ballast Using the Discrete Element Method

Track Geomechanics for Future Railways: Use of Artificial Inclusions

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