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Title: Spectral Analysis of Ground Acceleration-Based Testing
Accession Number: 01128756
Record Type: Component
Record URL: Availability: Transportation Research Board Business Office 500 Fifth Street, NW Find a library where document is available Abstract: Spectral analysis of downhole acceleration data is used to identify changes in elastic properties of track substructure. The spectral analysis is based on the power spectral density (PSD) as an indicator of frequency content. This method was developed and tested at the Transportation Technology Center, Inc., in Pueblo, Colorado. The system provides an efficient means for monitoring track bed to predict settlement and deformation conditions that would require maintenance. The method relies on a triaxial piezoelectric accelerometer inserted into a permanently installed inclinometer casing installed into the subgrade. Periodic measurement of the dynamic ground response allows for the identification of changes in the small strain elastic properties of the substructure layers. The methodology uses conventional downhole seismic shear wave velocity testing. For the purpose of comparison, test sections were constructed with clean and fouled ballast. Shear wave velocities indicated the differences in material properties. PSDs of the signals were analyzed to determine variation resulting from differences in soil conditions. PSDs were calculated at different intervals of loading. With increased loading, settlement of the subtrack soils occurs. The densification can be seen as an increase in the predominant frequency of the PSD. The PSD from the section with the clean ballast had a higher predominant frequency than the PSD from the section with the fouled ballast. A decrease in predominant frequency over time would indicate the decrease in stiffness and the potential of increased fouling of the ballast with fines. Changes in the frequency content would indicate changes in elastic response.
Monograph Title: Monograph Accession #: 01147420
Report/Paper Numbers: 09-2598
Language: English
Authors: Ho, Carlton LHyslip, James PLi, DingqingPagination: pp 50-56
Publication Date: 2009
ISBN: 9780309126335
Media Type: Print
Features: Figures
(7)
; References
(16)
TRT Terms: Uncontrolled Terms: Subject Areas: Maintenance and Preservation; Railroads; Terminals and Facilities; I22: Design of Pavements, Railways and Guideways; I60: Maintenance
Files: TRIS, TRB, ATRI
Created Date: Jan 30 2009 6:57PM
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