Over time, track ballast, consisting of crushed rock with large particles for drainage, tends to migrate downward into soft fill material. This generates zones of ballast mixed with soft fill, known as ballast pockets. Ballast pockets result in increasing voids in the subgrade, along with increased moisture content in the ballast pockets and decreased shear strength of the embankment soils. Geogrids have been used to stabilize railroad ballast by interlocking with the ballast, producing a type of rock mat foundation, and thereby reducing downward ballast migration. The inclusion of geogrid may reduce the quantity of ballast required and extend track maintenance cycles by limiting the rate of track settlement, and by retaining ballast above the geogrid where it can offer the most support. During a field study under heavy axle load conditions, Transportation Technology Center, Inc. (TTCI) evaluated track substructure instability problems caused by development of ballast pockets in soft clay and resultant shearing of the moist clay embankment. A multiaxial geogrid, along with ballast drains, was installed in October 2012 on a track with a long history of settlement issues. The track foreman in charge of repairs indicated that prior to the installation of the geogrid and drains that for the last 30 years ballast was added in this section on a weekly to bi-weekly basis. After five months of track use, the geogrid condition was examined and found to be in good condition with no damage observed, while continuing to support the ballast near the surface. This paper examines the performance of this section of track. It serves as useful information for future track bed remediation.


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    Titel :

    Track Remedation Using Geogrid with Drainage Improvement


    Beteiligte:
    Basye, Colin (Autor:in) / Kwon, Jayhyun (Autor:in)


    Erscheinungsdatum :

    2015


    Format / Umfang :

    5 Seiten, Bilder, Tabellen


    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Datenträger


    Sprache :

    Englisch




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