00475967

Component

http://onlinepubs.trb.org...trr/1987/1153/1153-002.pdf

https://scholar.google.co...mond&publication_year=1987

Large-scale models comprising a single tie/ballast system were constructed over artificial subballast-subgrade supports having variable compressibility ranging from rigid to very flexible (with California bearing ratio of 1). Test configurations included a 0.45-m depth of crushed limestone ballast conforming to an American Railway Engineering Association (AREA) Grading No. 4. A 920-mm-long by 250-mm-wide by 150-mm-deep steel footing was used to model the bearing area of a typical tie. Each rail seat was subjected to a program of repeated loading equivalent to a cumulative axle tonnage of 2 to 20 million tonnes in track. The performance of test sections reinforced with a single layer of geogrid at variable depths below the footing (tie) was compared against unreinforced test configurations. The results showed that geogrid reinforcement in ballast over compessible ballast support can be effective in reducing the rate of permanent deformation associated with lateral ballast spreading. The optimum reinforcement depth-to-tie-width ratio was determined to be from 0.2 to 0.4 for the single-tie tests with compressible artificial supports. No performance benefit was observed for reinforced ballast sections over a rigid support. By far the greatest influence on the performance of test sections was the compressibility of the artificial supports used. Permanent deformations at a given tonnage increased dramatically with increased support compressibility both for reinforced and unreinforced tests. A preliminary attempt was made to relate the performance of reinforced model tests to the performance of comparable configurations in track.

Publication of this paper sponsored by Committee on Mechanics of Earth Masses and Layered Systems . Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved

01416409

pp 8-14

1987

Transportation Research Record

0309046602

Print

Figures (10) ; References (12) ; Tables (1)

Accelerated tests; Ballast (Railroads); Compressibility; Crushed limestone; Deformation; Depth; Geogrids; Geotextiles; Material reinforcement; Mathematical models; Performance; Railroad ties; Repeated loads; Structural supports

Ballast; Models

Design; Geotechnology; Highways; Railroads

TRIS, TRB

Sep 30 1988 12:00AM

• DESIGN AND CONSTRUCTION OF REINFORCED EMBANKMENTS OVER WEAK FOUNDATIONS
• DESIGN AND PERFORMANCE OF A REINFORCED EMBANKMENT FOR MOHICANVILLE DIKE NO. 2 IN OHIO
• MODEL TESTS FOR STRIP FOUNDATION ON CLAY REINFORCED WITH GEOTEXTILE LAYERS
• REINFORCED ELASTIC LAYERED SYSTEMS