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Keywords: ballast settlement, full-scale track model, settlement model, light penetrometer test.

Summary

By means of a detailed parametric study of the settlement of ballast material performed on a full-scale track model, a predicting model for ballast settlement under cyclic loading has been developed. The model is based on track parameters: axle load, train speed and the initial mechanical state of ballast. A light dynamic penetrometer allows the characterization of the latter. Several loading tests, were performed, together with a characterization of the initial state of ballast close to the sleepers. Three hundred and sixty curves of settlement were obtained. The results show a settlement evolution in three stages (short, medium and long term settlement) depending on the initial conditions of the material and the intensity of the vibration. The settlement models reviewed in literature (Shenton, Hettler or Tom and Okley model) are not able to describe the entire evolution of the settlement curves. By developing a model based on the Chicago's density relaxation law, it is possible to estimate the evolution of settlement from the loading parameters and the initial mechanical state of the ballast material. From the database and studies of the Chicago experiments two governing parameters, can be identified, which represent the intensity of loading and cone resistance in coarse granular material. From these parameters it is possible to identify three functions which give the three parameters of the proposed model of the settlement. The proposed model describes the three stages in the settlement evolution. This model, si selected, for the results obtained in the global analysis of error by the MSE method. With this model, we obtain a prediction of settlement evolution with an error less than 10% for almost all experimental data. As a conclusion a method is prposed which has been tested on a track and which allows one to estimate the settlement of the sleepers by considering train traffic and cone penetration resistance in order to obtain an average settlement curve and a probability to reach a threshold value. This is a first step towards a general framework for the evaluation of the geometric potential degradation of railway tracks, which is a major issue for the cost reduction of maintenance operations on railway tracks.

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Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 104 PROCEEDINGS OF THE SECOND INTERNATIONAL CONFERENCE ON RAILWAY TECHNOLOGY: RESEARCH, DEVELOPMENT AND MAINTENANCE Edited by: J. Pombo Paper 121 Railway Ballast Settlement: A New Predictive Model G. Saussine¹, J.C. Quezada², P. Breul³ and F. Radjai⁴ ¹Innovation and Research, SNCF, Immeuble Lumiée, Paris, France ²Département Lignes Voie et Environnement, Direction Projets Systeme Ingenierie, SNCF, La Plaine St Denis, France ³Clermont Université, Université Blaise Pascal, Institut Pascal, CNRS, France ⁴Laboratoire de Mécanique et Génie Civil, Université Montpellier, CNRS, France doi:10.4203/ccp.104.121 purchase the full-text of this paper Full Bibliographic Reference for this paper G. Saussine, J.C. Quezada, P. Breul, F. Radjai, "Railway Ballast Settlement: A New Predictive Model", in J. Pombo, (Editor), "Proceedings of the Second International Conference on Railway Technology: Research, Development and Maintenance", Civil-Comp Press, Stirlingshire, UK, Paper 121, 2014. doi:10.4203/ccp.104.121 Keywords: ballast settlement, full-scale track model, settlement model, light penetrometer test. Summary By means of a detailed parametric study of the settlement of ballast material performed on a full-scale track model, a predicting model for ballast settlement under cyclic loading has been developed. The model is based on track parameters: axle load, train speed and the initial mechanical state of ballast. A light dynamic penetrometer allows the characterization of the latter. Several loading tests, were performed, together with a characterization of the initial state of ballast close to the sleepers. Three hundred and sixty curves of settlement were obtained. The results show a settlement evolution in three stages (short, medium and long term settlement) depending on the initial conditions of the material and the intensity of the vibration. The settlement models reviewed in literature (Shenton, Hettler or Tom and Okley model) are not able to describe the entire evolution of the settlement curves. By developing a model based on the Chicago's density relaxation law, it is possible to estimate the evolution of settlement from the loading parameters and the initial mechanical state of the ballast material. From the database and studies of the Chicago experiments two governing parameters, can be identified, which represent the intensity of loading and cone resistance in coarse granular material. From these parameters it is possible to identify three functions which give the three parameters of the proposed model of the settlement. The proposed model describes the three stages in the settlement evolution. This model, si selected, for the results obtained in the global analysis of error by the MSE method. With this model, we obtain a prediction of settlement evolution with an error less than 10% for almost all experimental data. As a conclusion a method is prposed which has been tested on a track and which allows one to estimate the settlement of the sleepers by considering train traffic and cone penetration resistance in order to obtain an average settlement curve and a probability to reach a threshold value. This is a first step towards a general framework for the evaluation of the geometric potential degradation of railway tracks, which is a major issue for the cost reduction of maintenance operations on railway tracks. purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £65 +P&P)
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