Influence of Under Sleeper Pads on Ballast Behavior Under Cyclic Loading: Experimental and Numerical Studies

Navaratnarajah, S. K.; Indraratna, Buddhima; Ngo, Ngoc Trung

doi:10.1061/(asce)gt.1943-5606.0001954

Cited by 87 publications

(25 citation statements)

References 26 publications

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“…This is due to the fact that the CR can induce insufficiently soft contacts between the sleeper and RPB particles, which has been proved in [54], where the soft contacts led to higher sleeper accelerations. However, in some earlier studies on the under sleeper pads (USPs) [21,22,55], they argued that the soft contacts can provide a better ballast bed performance by reducing the ballast degradation. Particularly, the difference between the USPs and RPB is that the USPs attach to the sleeper bottom without any movement and the ballast particles' rearrangement is slow, whereas RPB particles can move randomly after applied loadings and the interaction between particles is not strong enough to restrict RPB particles.…”

Section: Contact Forcementioning

confidence: 99%

Discrete Element Modelling of Rubber-Protected Ballast Performance Subjected to Direct Shear Test and Cyclic Loading

Guo

Zhou

et al. 2020

Sustainability

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The rubber-protected ballast (RPB) is made from natural ballast particles and crumb rubber particles. The crumb rubber is shredded waste tires. RPB was chosen to replace the ballast as it has higher resistance to breakage and abrasion. However, the static and dynamic performance of the RPB has not been confirmed yet. Towards this end, experimental tests and numerical simulations were utilized to study the feasibility of RPB application. Direct shear tests (DSTs) were performed and a DST model and three-sleeper track model with the discrete element method (DEM) were built. The shear strength, settlement, displacement, and acceleration of the RPB were studied. The results show that the RPB has the advantage of increasing the force (stress) distribution and that the smaller crumb rubber size was more suitable for replacing the ballast particles.

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Section: Contact Forcementioning

confidence: 99%

Discrete Element Modelling of Rubber-Protected Ballast Performance Subjected to Direct Shear Test and Cyclic Loading

Guo

Zhou

et al. 2020

Sustainability

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“…The deterioration (breakage) of ballast is one of the major contributing factors which affect the stability and longevity of railway foundations (Tutumluer et al 2012;Sun et al 2018;Le Pen et al 2011;Ngo et al 2017). The adoption of various forms of geosynthetic inclusions, such as geogrids and rubber energy absorbing drainage sheets (READS) produced from recycled tires to reduce the plastic deformation and breakage of ballast has become increasingly popular worldwide (Navaratnarajah et al 2018;Abadi et al 2019;Indraratna et al 2016). These synthetic inclusions eliminate hard interfaces between ballast aggregates and concrete sleepers or the underlying formation soils, and allow the aggregates to bed into the relatively softer pads, thus increasing the contact surface area of the ballast and reducing ballast stresses.…”

Section: Introductionmentioning

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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“…These impact forces can likewise be generated at transition zones involving abrupt variations of vertical track stiffness, such as at the approaches to tunnels, bridge or viaduct and level crossings, or where there is a sudden change from conventional ballast to slab track intensifying ballast breakage and adversely affecting track stability [11][12][13][14][15]. One potential method of enhancing the substructure capacity to withstand the large cyclic and impact loads induced by fast-moving heavy-haul trains is to improve the performance of the ballast layer using plastic (e.g., geogrids) and rubber inclusions (e.g., rubber mat, tire cell, and rubber crumbs) [2,[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

“…The high damping properties of rubber materials have made them a promising inclusion for rail track as to enhance the energy absorbing characteristics of rail tracks, as well as reduce noise, vibration, ballast degradation and impact damage to track components [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30]. Since these rubber materials can be made from end-of-life tires, they are environmentally friendly and economically attractive, promoting optimism and exploration into the potential use of rubber materials in rail foundations.…”

Section: Introductionmentioning

confidence: 99%

Use of Geogrids and Recycled Rubber in Railroad Infrastructure for Enhanced Performance

Indraratna

Ngo

et al. 2019

Geosciences

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Railway tracks are conventionally built on compacted ballast and structural fill layers placed above the natural (subgrade) foundation. However, during train operations, track deteriorations occur progressively due to ballast degradation. The associated track deformation is usually accompanied by a reduction in both load bearing capacity and drainage, apart from imposing frequent track maintenance. Suitable ground improvement techniques involving plastic inclusions (e.g., geogrids) and energy absorbing materials (e.g., rubber products) to enhance the stability and longevity of tracks have become increasingly popular. This paper presents the outcomes from innovative research and development measures into the use of plastic and rubber elements in rail tracks undertaken at the University of Wollongong, Australia, over the past twenty years. The results obtained from laboratory tests, mathematical modelling and numerical modelling reveal that track performance can be improved significantly by using geogrid and energy absorbing rubber products (e.g., rubber crumbs, waste tire-cell and rubber mats). Test results show that the addition of rubber materials can efficiently improve the energy absorption of the structural layer and also reduce ballast breakage. Furthermore, by incorporating the work input parameters, the energy absorbing property of the newly developed synthetic capping layer is captured by correct modelling of dilatancy. In addition, the laboratory behavior of tire cells and geogrids has been validated by numerical modelling (i.e., Finite Element Modelling-FEM, Discrete Element—DEM), and a coupled DEM-FEM modelling approach is also introduced to simulate ballast deformation.

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Influence of Under Sleeper Pads on Ballast Behavior Under Cyclic Loading: Experimental and Numerical Studies

Cited by 87 publications

References 26 publications

Discrete Element Modelling of Rubber-Protected Ballast Performance Subjected to Direct Shear Test and Cyclic Loading

Discrete Element Modelling of Rubber-Protected Ballast Performance Subjected to Direct Shear Test and Cyclic Loading

Advancement of Rail Ballast Testing Methodologies and Design Implications

Use of Geogrids and Recycled Rubber in Railroad Infrastructure for Enhanced Performance

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