Measurement of probabilistic ballast particle dynamics using Kli-Pi
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Date
Authors
Broekman, Andre
Grabe, Petrus Johannes
Journal Title
Journal ISSN
Volume Title
Publisher
South African Institution of Civil Engineering
Abstract
At first glance the operational performance of ballast appears trivial in its simplicity. However,
various mechanisms affect the performance of the ballast both on a macroscopic scale and
discrete (mesoscale) particle level. The importance of experimental studies to establish the
influence of the granular fabric has been highlighted repeatedly by other researchers. This paper
describes a method by which quantitative metrics and statistics can describe the probabilistic
response of railway ballast. The measurements were obtained with the installation of a set of
customised wireless inertial measurement unit (IMU), referred to as Kli-Pi, in the granular layers
of a heavy-haul railway line located in South Africa. The results indicate a complex interaction of
displacement and rotation, in all three spatial dimensions. The high-frequency measurements
provided approximations of the particle’s kinetic and potential energy (mechanical work) in
addition to the indirect quantification of changes to the granular fabric. Finally, the descriptive
statistics of the mechanical work provided an indirect measure of the confinement and
coordination number of the particle, together with supporting evidence of the underlying
probabilistic, instead of the expected deterministic response. These results strongly agree with the
findings of existing literature that has, to date, been confined to theoretical study.
Description
Keywords
Probabilistic ballast particle dynamics, Smart ballast instrumentation, Kli-Pi, Granular fabric quantification, Mesoscale ballast dynamics, Impact loading
Sustainable Development Goals
Citation
Broekman A, Gräbe PJ. Measurement of probabilistic ballast particle dynamics using Kli-Pi. Journal of the South African Institution of Civil Engineering 2021:63(1), Art. #966,13 pages. http://dx.DOI.org/10.17159/2309-8775/2021/v63n1a2.