00300675

Component

http://onlinepubs.trb.org...s/trr/1978/694/694-008.pdf

https://scholar.google.co...Sluz&publication_year=1978

Ballast and subgrade play major roles in the maintenance life of track structures because they are the source of the cumulative permanent deformation associated with the deterioration of surface and line. Ballast is also the principal means of correcting for this deterioration, which is caused by traffic and environmental factors. Better methods are still needed for the prediction of the effects of the controlling parameters on track performance for more rational track design and maintenance planning. The purpose of this paper is to provide a better understanding of these problems and describe progress being made toward their solution. The functions of ballast and subgrade are briefly discussed, and the mechanisms of permanent deformation are described. Newly developed or improved methods to measure the in situ physical state of ballast are presented, and examples of results from field tests are given. The capabilities of existing analytical track structure models for the prediction of track deterioration are assessed. New instrumentation techniques used for measuring the dynamic and permanent strains and deformations in ballast and subgrade are described. Finally, the characteristics of the stress, strain, and deformation in ballast and subgrade are illustrated with results of both analytical and experimental studies.

Publication of this paper sponsored by Committee on Track Structure System Design. 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.

01411530

pp 53-60

1978

Transportation Research Record

030902840X

Print

Figures (12) ; References (20)

Ballast (Railroads); Deformation; Instrumentation; Mathematical models; Mechanical properties; Railroad tracks; Structural design; Subgrade (Pavements); Test procedures; Traffic density

Track geometry

Geotechnology; Highways; Railroads

TRIS, TRB

Sep 29 1979 12:00AM

• ANALYTICAL AND EXPERIMENTAL STUDY OF RESIDUAL STRESS IN RAILS
• DEVELOPMENT OF MULTILAYER ANALYSIS MODEL FOR TIE-BALLAST TRACK STRUCTURES
• EFFECTS OF ENERGY-COST VARIATION ON FEASIBILITY OF ELECTRIFYING THE CINCINNATI-ATLANTA MAIN LINE OF THE SOUTHERN RAILWAY SYSTEM
• INTRODUCTION TO STRESSES IN RAILS: STRESSES IN MIDRAIL REGIONS
• MATHEMATICAL MODEL FOR LATERAL THERMAL BUCKLING AND DISPLACEMENT OF CURVED TRACK
• PERMANENT-DEFORMATION BEHAVIOR OF RAILWAY BALLAST
• PREDICTION OF FATIGUE CRACK GROWTH IN RAILROAD RAILS
• STATISTICAL DESCRIPTION OF SERVICE LOADS FOR CONCRETE CROSSTIE TRACK
• TECHNIQUES FOR EVALUATING EFFECTS OF TRACK AND VEHICLE WEAR ON FREIGHT-CAR PERFORMANCE