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O. Barbir, D. Adam, F. Kopf, J. Pistrol, F. Auer, B. Antony:
"Semi-analytical approach to ballast bed modelling during compaction";
Talk: 27th European Young Geotechnical Engineers Conference, Bodrum, Turkey (invited); 2019-06-26 - 2019-06-27; in: "Proceedings of the 27th European Young Geotechnical Engineers Conference", Turkish Society for ISSMGE, Bodrum, Turkey (2019), 7 - 12.

Throughout the world, the condition of the ballast bed is one of the most important parameters for a safe and economical operation of railway systems. Better knowledge of ballast condition provides an advantage in defining the optimum time for ballast bed cleaning or renewal. Tamping process is the core maintenance activity in ballasted track and it is crucial to the economical service life of the track and essential in restoring the track geometry for safe train operations. During the tamping process, the tamping tines interact with the ballast matrix, transferring the displacement caused by the dynamic excitation to the ballast, compacting it under the sleeper. This interaction is observed and measured in-situ within the framework of this research project. Serving as a mean of comparison and confirmation with the conducted in-situ measurements, a semi-analytical model of the tamping unit - ballast matrix interaction is developed. The tamping unit is presented by a simple system of rods with a dynamic excitation overlapped by a hydraulic cylinder movement modelled with a variable rod length. The ground model is based on a semi-infinite truncated cone for vertical translation, the half space being represented by the Kelvin-Voigt model [5], which consists of a purely elastic spring and a purely viscous damper connected in parallel. The soil model has been extended by an additional plastic spring, modelling the plastic deformation of the ballast matrix, i.e. its compaction under the sleeper. The ballast model described presents a reliable method of modeling non-cohesive soils, and can as such be implemented on other granular materials under dynamic loading.

track tamping, track ballast compaction, semi-analytical modelling

https://publik.tuwien.ac.at/files/publik_281687.pdf