Characterization of the Fouled Ballast Layer in the Substructure of a 19th Century Railway Track Under Renewal

Fortunato, Eduardo; Pinelo, António; Fernandes, Manuel Matos

doi:10.3208/sandf.50.55

Cited by 29 publications

(13 citation statements)

References 3 publications

(2 reference statements)

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“…Moreover, due to progressive degradation and the infiltration of fine particles and mud-pumping from the lower subgrade , ballast becomes fouled, which adversely affects the strength and deformation of ballasted tracks (Budiono et al 2004;Lackenby et al 2007;Tutumluer et al 2008;Fortunato et al 2010;Indraratna et al 2013). Given the typical Australian coal freight tracks, Feldman and Nissen (2002) reported that dry coal fines are responsible for 70-95% of the fouling materials in rail tracks.…”

Section: Introductionmentioning

confidence: 99%

Modelling geogrid-reinforced railway ballast using the discrete element method

Ngo

Indraratna

Rujikiatkamjorn

2016

Transportation Geotechnics

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Rail ballast is an unbounded granular material that spreads laterally when subjected to train loading. Railroads can be reinforced by geogrids to reduce lateral movement and to optimize track performance. This paper presents a study of the behaviour of geogrid-reinforced ballast subjected to monotonic and cyclic loading using a large-scale direct shear box and a novel Track Process Simulation Apparatus (TPSA). The shear stressstrain response of fresh and fouled ballast reinforced by geogrid was investigated using large-scale direct shear tests subjected to normal stresses from 15 kPa to 75 kPa, where the levels of fouling varied from 20% to 95% Void Contamination Index (VCI). Cyclic tests for fresh and fouled ballast were conducted using the TPSA to realistically simulate real track conditions. The experimental results showed that a geogrid provides extra internal confinement and interlocks the aggreagtes in its apertures, hence reduces ballast deformation. The discrete element method (DEM) was used to model geogrid-reinforced fresh and fouled ballast subjected to monotonic and cyclic loading. Irregularly-shaped particles and geogird were simulated by clumping spherical balls together, while the coal fines were simulated by adding 1.5mm diameter spheres into the pore spaces of ballast. The predicted stress-displacement responses obtained from the DEM were in good agreement with those measured in the laboratory, where the peak shear stress of fouled ballast decreased and the dilation of fouled ballast increased with an increasing level of fouling. The contact force distributions and the orientations of normal and shear force were analyzed to provide more insight into the behaviour of ballast subjected to shearing. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. ABSTRACTRail ballast is an unbounded granular material that spreads laterally when subjected to train loading. Railroads can be reinforced by geogrids to reduce lateral movement and to optimize track performance. This paper presents a study of the behaviour of geogrid-reinforced ballast subjected to monotonic and cyclic loading using a large-scale direct shear box and a novel Track Process Simulation Apparatus (TPSA). The shear stress-strain response of fresh and fouled ballast reinforced by geogrid was investigated using large-scale direct shear tests subjected to normal stresses from 15 kPa to 75 kPa, where the levels of fouling varied from 20% to 95% Void Contamination Index (VCI). Cyclic tests for fresh and fouled ballast were conducted using the TPSA to realistically simulate real track conditions. The experimental results showed th...

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Section: Introductionmentioning

confidence: 99%

Modelling geogrid-reinforced railway ballast using the discrete element method

Ngo

Indraratna

Rujikiatkamjorn

2016

Transportation Geotechnics

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“…The early stage detection of ballast fouling is therefore a crucial factor to extend its life cycle. To that effect, GPR has been successfully used to distinguish clean from fouled ballast [32][33][34]. This differentiation was possible because clean ballast is associated with the diffraction of the electromagnetic waves in its open voids [14].…”

Section: Overview On the Use Of Gpr For Railway Monitoringmentioning

confidence: 99%

Railway Track Condition Assessment at Network Level by Frequency Domain Analysis of GPR Data

et al. 2018

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Abstract:The railway track system is a crucial infrastructure for the transportation of people and goods in modern societies. With the increase in railway traffic, the availability of the track for monitoring and maintenance purposes is becoming significantly reduced. Therefore, continuous non-destructive monitoring tools for track diagnoses take on even greater importance. In this context, Ground Penetrating Radar (GPR) technique results yield valuable information on track condition, mainly in the identification of the degradation of its physical and mechanical characteristics caused by subsurface malfunctions. Nevertheless, the application of GPR to assess the ballast condition is a challenging task because the material electromagnetic properties are sensitive to both the ballast grading and water content. This work presents a novel approach, fast and practical for surveying and analysing long sections of transport infrastructure, based mainly on expedite frequency domain analysis of the GPR signal. Examples are presented with the identification of track events, ballast interventions and potential locations of malfunctions. The approach, developed to identify changes in the track infrastructure, allows for a user-friendly visualisation of the track condition, even for GPR non-professionals such as railways engineers, and may further be used to correlate with track geometric parameters. It aims to automatically detect sudden variations in the GPR signals, obtained with successive surveys over long stretches of railway lines, thus providing valuable information in asset management activities of infrastructure managers.

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“…LNEC's experience in laboratory for materials characterization with GPR began 15 years ago, when GPR tests were performed for the first time on Portuguese railways [18,20]. Therefore, beside the recently acquired antenna all the laboratory tests were performed also with four other antennas of frequencies between 500 and 1800 MHz, generally used for railways and pavement evaluation at LNEC.…”

Section: Introductionmentioning

confidence: 99%

“…In particular, laboratory tests for determining the dielectric properties of infrastructure materials have been performed along several years in different countries, as materials used in the infrastructure are different for different design procedures [17][18][19][20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

GPR Laboratory Tests For Railways Materials Dielectric Properties Assessment

2014

Self Cite

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Abstract:In railways Ground Penetrating Radar (GPR) studies, the evaluation of materials dielectric properties is critical as they are sensitive to water content, to petrographic type of aggregates and to fouling condition of the ballast. Under the load traffic, maintenance actions and climatic effects, ballast condition change due to aggregate breakdown and to subgrade soils pumping, mainly on existing lines with no sub ballast layer. The main purpose of this study was to validate, under controlled conditions, the dielectric values of materials used in Portuguese railways, in order to improve the GPR interpretation using commercial software and consequently the management maintenance planning. Different materials were tested and a broad range of in situ conditions were simulated in laboratory, in physical models. GPR tests were performed with five antennas with frequencies between 400 and 1800 MHz. The variation of the dielectric properties was measured, and the range of values that can be obtained for different material condition was defined. Additionally, in situ GPR measurements and test pits were performed for validation of the dielectric constant of clean ballast. The results obtained are analyzed and the main conclusions are presented herein.

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Characterization of the Fouled Ballast Layer in the Substructure of a 19th Century Railway Track Under Renewal

Cited by 29 publications

References 3 publications

Modelling geogrid-reinforced railway ballast using the discrete element method

Modelling geogrid-reinforced railway ballast using the discrete element method

Railway Track Condition Assessment at Network Level by Frequency Domain Analysis of GPR Data

GPR Laboratory Tests For Railways Materials Dielectric Properties Assessment

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