Effects of ballast degradation on permanent deformation behavior from large-scale triaxial tests

Yu Qian, Erol Tutumluer, Youssef M.A. Hashash, Jamshid Ghaboussi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Consisting of large sized aggregate particles with uniform size distribution, ballast is an essential component of the track substructure to facilitate load distribution and drainage. As freight tonnage accumulates with traffic, ballast will get fouled increasingly due to either aggregate breakdown and degradation or contamination by other materials such as coal dust and subgrade soil intrusion. Fouling affects shear strength and load carrying ability of ballast layer especially under wet conditions. According to Selig and Waters [1], ballast fouling is often due to aggregate degradation, which covers up to 76% of all the fouling cases. To investigate the effects of ballast aggregate breakdown and degradation on the mechanical behavior of fouled ballast, a series of Los Angeles abrasion tests were performed in this study to generate fouled ballast materials caused by particle breakage and abrasion under a wellcontrolled laboratory environment. The change of particle shape properties during the Los Angeles abrasion tests was quantified and studied through image analysis technology. Large-scale triaxial tests were performed on specimens of new ballast, degraded ballast coarse particle fraction (without fines), and full gradation of degraded ballast (with fines) under repeated load application using a triaxial test device recently developed at the University of Illinois specifically for ballast size aggregate materials. The large-scale triaxial results indicated that the specimen having those degraded coarse particles yielded higher permanent deformation trends from repeated load triaxial testing when compared to the specimen with the new ballast gradation. As expected, the highest permanent deformation was obtained from the degraded ballast specimen having fine particles and the Fouling Index (FI) value of approximately 40.

Original languageEnglish (US)
Title of host publication2014 Joint Rail Conference, JRC 2014
PublisherAmerican Society of Mechanical Engineers (ASME)
ISBN (Print)9780791845356
DOIs
StatePublished - 2014
Event2014 Joint Rail Conference, JRC 2014 - Colorado Springs, CO, United States
Duration: Apr 2 2014Apr 4 2014

Publication series

Name2014 Joint Rail Conference, JRC 2014

Other

Other2014 Joint Rail Conference, JRC 2014
CountryUnited States
CityColorado Springs, CO
Period4/2/144/4/14

ASJC Scopus subject areas

  • Transportation

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