Stress-dilatancy behaviour of fouled ballast: experiments and DEM modelling

Ballast consisting of large sized aggregate particles with uniform size distribution is an essential component of the track substructure, to facilitate load distribution and drainage. As freight tonnage accumulates with traffic, ballast will accumulate an increasing percentage of fines due to either aggregate breakdown or outside contamination such as subgrade soil intrusion and coal dust collection. According to the classical text by Selig and Waters [1], ballast degradation from traffic involves up to 76% of all fouling cases; voids will be occupied by fines from the bottom of ballast layer gradually causing ballast clogging and losing its drainage ability. When moisture is trapped within ballast, especially fouled ballast, ballast layer stability is compromised. In the recent studies at the University of Illinois, the focus has been to evaluate behavior of fouled ballast due to aggregate degradation using large scale triaxial testing. To investigate the effects of moisture on degraded ballast, fouled ballast was generated in the laboratory through controlled Los Angeles (LA) abrasion tests intended to mimic aggregate abrasion and breakdown and generate fouled ballast at compositions similar to those observed in the field due to repeated train loadings. Triaxial shear strength tests were performed on the fouled ballast at different moisture contents. Important findings of this preliminary study on characterizing wet fouled ballast are presented in this paper. Moisture was found to have a significant effect on the fouled ballast strength behavior. Adding a small amount of 3% moisture (by weight of particles smaller than 3/8 in. size or smaller than 9.5 mm) caused test specimens to indicate approximately 50% decrease in shear strength of the dry fouled ballast. Wet fouled ballast samples peaked at significantly lower maximum deviator stress values at relatively smaller axial strains and remained at these low levels as the axial strain was increased.

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Deformation of Coal Fouled Ballast Stabilized with Geogrid under Cyclic Load

Journal of Geotechnical and Geoenvironmental Engineering ◽

10.1061/(asce)gt.1943-5606.0000864 ◽

2013 ◽

Vol 139 (8) ◽

pp. 1275-1289 ◽

Cited By ~ 61

Author(s):

Buddhima Indraratna ◽

Ngoc Trung Ngo ◽

Cholachat Rujikiatkamjorn

Keyword(s):

Cyclic Load ◽

Fouled Ballast

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Laboratory Validation of Coal Dust Fouled Ballast Discrete Element Model

Paving Materials and Pavement Analysis ◽

10.1061/41104(377)37 ◽

2010 ◽

Cited By ~ 3

Author(s):

Hai Huang ◽

Erol Tutumluer ◽

Youssef M. A. Hashash ◽

Jamshid Ghaboussi

Keyword(s):

Coal Dust ◽

Element Model ◽

Discrete Element ◽

Discrete Element Model ◽

Fouled Ballast

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Effect of sand-fouled ballast on train-induced vibration

International Journal of Pavement Engineering ◽

10.1080/10298436.2013.818146 ◽

2013 ◽

Vol 15 (7) ◽

pp. 635-644 ◽

Cited By ~ 11

Author(s):

Morteza Esmaeili ◽

Jabbar Ali Zakeri ◽

Seyed Ali Mosayebi

Keyword(s):

Fouled Ballast ◽

Train Induced Vibration

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Evaluating the Effect of Breakdown Fouling and Water Content on the Ballast Degradation Characteristics

2017 Joint Rail Conference ◽

10.1115/jrc2017-2215 ◽

2017 ◽

Author(s):

Hamed Faghihi Kashani ◽

Carlton L. Ho ◽

James P. Hyslip

Keyword(s):

Water Content ◽

Large Scale ◽

Field Capacity ◽

Strength Properties ◽

Engineering Properties ◽

Fouled Ballast ◽

Confining Pressures ◽

University Of Massachusetts ◽

Moisture Conditions ◽

The University

Railroad ballast as a layer of track substructure performs important tasks such as increasing the bearing capacity of the sleepers, providing large voids for drainage and resisting the forces applied to the super-structure. Contamination of ballast as the result of ballast breakdown known as breakdown fouling can prevent ballast from performing its job and also affects the engineering properties of ballast. This paper discusses the drained static triaxial testing on granite ballast material with different amount of breakdown fouling and water content. Large-scale triaxial equipment was used for this testing program at the University of Massachusetts, Amherst. These tests were performed to study the effect of fouling and water content, on the strength properties and degradation characteristics of railroad ballasted track. Ballast with three different fouling percentages from clean to highly fouled ballast (<5%, 15% and 30%) and four water contents from dry to field capacity were tested under three different confining pressures. The results show that although an increase in moisture degrades the fouled ballast, increase in breakdown fouling at constant moisture conditions increases the strength of the ballast.

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A study of the behaviour of fresh and coal fouled ballast reinforced by geogrid using the discrete element method

Geomechanics from Micro to Macro ◽

10.1201/b17395-100 ◽

2014 ◽

pp. 559-563

Author(s):

N Ngo ◽

B Indraratna ◽

C Rujikiatkamjorn

Keyword(s):

Discrete Element Method ◽

Discrete Element ◽

Fouled Ballast ◽

Element Method

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Forward-Looking Infrared Radiometry (FLIR) Application for Detecting Ballast Fouling

2020 Joint Rail Conference ◽

10.1115/jrc2020-8032 ◽

2020 ◽

Author(s):

SayedMohammad Hosseini ◽

Yongwen Tan ◽

Mehdi Ahmadian

Keyword(s):

Field Testing ◽

Measured Temperature ◽

Water Drainage ◽

Fouled Ballast ◽

Effective Manner ◽

Environmental Variations ◽

Infrared Radiometry ◽

Set Up ◽

Railroad Applications ◽

Forward Looking

Abstract This paper is intended to assess the practical aspects of the previously proposed approach for detecting railroad ballast fouling using an off-the-shelf Forward-Looking Infrared Radiometry (FLIR) Technology. FLIR is among the technologies that are becoming more prevalent in railroad applications [1,2]. The method discussed in this paper takes advantage of the temperature differences measured by the FLIR camera between the top surface of clean and partially fouled ballast samples as an indicator of fouling. The method is intended to potentially serve as an efficient and time-effective manner for detecting early stages of ballast fouling prior to it requiring a costly intervention. Ballast fouling is a common maintenance-of-way issue for the railroad industry, which occurs as a result of contaminants clogging up the ballast and preventing water drainage. The water retained at the sublayers diminishes the strength of the foundation and could result in other undesirable conditions such as clay pumping and reduced track strength. In this study, experiments are performed to study the thermal behavior and characteristics of clean, and partially- and fully-fouled ballast using a FLIR camera. The FLIR camera is set up in a stationary configuration for ease of testing and also providing a more direct approach to analyzing the data, to keep the test conditions highly repeatable and reduce any environmental variations. The results indicate that the cooling and heating rate at the top surface for clean, partially fouled, and fouled ballast are different during the daily heat-up cycle. It is determined that although the FLIR camera is able to measure some changes in the ballast temperature for the fouling conditions that are evaluated in the study, the differences may be within the range of variations that could occur in field conditions. The paper includes the range of measured temperature by the FLIR camera and discusses the pros and cons of using this approach in practice. Additional field testing is needed to validate or dispute the initial findings of the study.

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Shear Strength and Drainage Characteristics of Elastomeric Polyurethane Treated Coal-Fouled Ballast

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/03611981211036375 ◽

2021 ◽

pp. 036119812110363

Author(s):

Syed Khaja Karimullah Hussaini ◽

Dinesh Gundavaram

Keyword(s):

Shear Strength ◽

Large Scale ◽

Empirical Relationship ◽

Direct Shear ◽

Shear Tests ◽

Contamination Index ◽

Direct Shear Tests ◽

Fouled Ballast ◽

Constant Head ◽

Fouling Materials

The shear behavior and drainage characteristics of coal-fouled ballast when treated with elastomeric polyurethane are assessed by means of large-scale direct shear and permeability tests. The results from direct shear tests confirmed that the shear strength of both stabilized and unstabilized coal-fouled ballast was highly influenced by the extent of fouling (VCI: void contamination index). The performance index (PI) of elastomer-stabilized coal-fouled ballast (ESFB), determined as the fraction of shear strength of fouled ballast to the shear strength of fresh and unstabilized ballast, lies in the range of 1.23 to 0.84. Moreover, the performance of ESFB having VCI ≥30% was found to be either similar to or poorer than that of clean ballast without any treatment, thus indicating that the elastomer treatment may be provided only to ballast with VCI ≤30%. The results from constant head permeability tests indicate that the hydraulic conductivity of ballast ( k) is highly influenced by the presence of fouling materials but is only slightly reduced as a result of the elastomer stabilization. The k of ballast decreased from 43 to 0.18 mm/s as the VCI increased from 0 to 75%. For VCI ≥ 45% the k of ballast was found to be lower than that recommended for sub-ballast. On the other hand, the k of ballast reduced slightly from 43 to 37 mm/s because of the elastomer stabilization. Furthermore, an empirical relationship is established between k and e to determine the k of both stabilized and unstabilized fouled ballast.

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