00457448

Component

http://onlinepubs.trb.org...trr/1985/1022/1022-008.pdf

https://scholar.google.co...gory&publication_year=1985

In conventional track systems the ties are supported by an unbound ballast layer underlain by subballast or the subgrade, or both. Analytical models used to estimate stresses and deflections of these multilayer systems predict that the lower portions of the unbound layer will develop significant incremental tensile stresses. Their magnitude is such that, when combined with the normally expected geostatic stresses, failure of the ballast is predicted. Some analytical models have incorporated failure criteria for the unbound layer as a means of limiting these stresses to permissible values. A discussion of these approaches is presented along with the implications that predicted failure would have for permanent deformation prediction methodologies. An alternative method based on residual lateral stresses in the ballast is presented. A description is given of a laboratory box testing device used to measure residual lateral stresses. Experimental results are shown that indicate that relatively large residual stresses, due to repeated applications of loading, can develop in ballast. The effects of combining the initial stresses in the unbound layer with the incremental tensile stresses predicted by continuum or finite element models are discussed. Particular attention is given to the effects that these residual stresses have on prediction of permanent deformation.

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

01419404

pp 59-64

1985

Transportation Research Record

0309039118

Print

Figures (9) ; Photos (1) ; References (8)

Accuracy; Ballast (Railroads); Deflection; Deformation; Failure; Forecasting; Foundations; Railroad tracks; Subgrade (Pavements)

Ballast; Failure criterion; Lateral stress

Geotechnology; Highways; Pavements; Railroads; I42: Soil Mechanics

TRIS, TRB

Aug 31 1986 12:00AM

• ANALYSIS OF TRACK SUPPORT AND DETERMINATION OF TRACK MODULUS
• Analytical-Empirical Pavement Evaluation Using the Falling Weight Deflectometer
• APPLICATION OF SIMPLIFIED LAYERED SYSTEMS TO NDT PAVEMENT EVALUATION
• AUTOMATED CONE PENETROMETER: A NONDESTRUCTIVE FIELD TEST FOR SUBGRADE EVALUATION
• BEHAVIOR OF STABILIZED LAYERS UNDER REPEATED LOADS
• CHARACTERIZATION OF GRANULAR MATERIAL
• DYNAMIC INTERPRETATION OF DYNAFLECT AND FALLING WEIGHT DEFLECTOMETER TESTS
• EVALUATION OF PAVEMENT SUBGRADE SUPPORT CHARACTERISTICS BY DILATOMETER TEST
• FLAT DILATOMETER AND LATERAL SOIL MODULUS
• MEASUREMENT AND PREDICTION OF VERTICAL TRACK MODULUS
• MODELING OF GRANULAR MATERIALS IN PAVEMENTS
• NEW METHOD OF SIMULATING LAYERED SYSTEMS OF UNBOUND GRANULAR MATERIAL
• PAVEMENT DESIGN BASED ON SHAKEDOWN ANALYSIS
• Pavement Evaluation Using Deflection Basin Measurements and Layered Theory (Discussion and Closure)
• PAVEMENT FAILURE INVESTIGATION: CASE STUDY (ABRIDGMENT)
• RAPID DETERMINATION OF BASE COURSE STRENGTH USING THE CLEGG IMPACT TESTER
• THEORETICAL RESPONSE OF MULTILAYER PAVEMENT SYSTEMS TO DYNAMIC NONDESTRUCTIVE TESTING