United States Department of Transportation
ROSA P serves as an archival repository of USDOT-published products including scientific findings, journal articles, guidelines, recommendations, or other information authored or co-authored by USDOT or funded partners.
As a repository, ROSA P retains documents in their original published format to ensure public access to scientific information.
i
A Semi-Flexible Composite Trackbed Material for Stiffness Transition in Bridge Approaches and Its Application
-
2020-09-30
-
[PDF-1.91 MB]
Details:
-
Creators:
-
Corporate Creators:
-
Corporate Contributors:
-
Subject/TRT Terms:
-
Publication/ Report Number:
-
Resource Type:
-
Geographical Coverage:
-
Edition:Final Report 03/11/2019 – 09/30/2020
-
Corporate Publisher:
-
Abstract:When railroad tracks extend from a subgrade to a bridge, the abrupt variation of the stiffness or track moduli can lead to transition problems. This is mainly due to a major settlement difference of the foundation and can cause a discontinuity of the track structure. If handled inappropriately, these problems would eventually accelerate the degradation of the railway tracks. Various approaches, focusing on either component modification or structure adjustment, have been tried to mitigate the transition problem. In particular, setting an asphalt track is an effective approach, as it provides enough support to the ballast layer and additional protection to the soil subgrade. However, the limited range of the modulus of the asphalt mixture restricts its application to the railway transition zone. Therefore, a semi-flexible composite mixture (SFCM), which combines the strengths of the asphalt mixture and cement concrete, is proposed in this study as a promising alternative for the asphalt mixture. This research investigated the factors affecting the volumetric and mechanical properties of the SFCM and found that the SFCM is a viscoelastic material and its dynamic modulus could adjust with the air voids of the composite materials and the proportion of the cement slurry. A simulation was then conducted to study the response of the railway track under the dynamic load and evaluate how the SFCM material can be practically used. After different trials of track structures and material, four segments of the transition zones were proposed to make the vertical displacement transition smoothly from the soil subgrade to the cement concrete.
-
Format:
-
Funding:
-
Collection(s):
-
Main Document Checksum:
-
Download URL:
-
File Type:
