SPECIFIC EVALUATION METHODOLOGY OF RAILWAY BALLAST PARTICLES’ DEGRADATION

ISSN 2307–3489 (Print), ІSSN 2307–6666 (Online) Наука та прогрес транспорту. Вісник Дніпропетровського національного університету залізничного транспорту, 2019, № 3 (81) ЗАЛІЗНИЧНА КОЛІЯ ТА АВТОМОБІЛЬНІ ДОРОГИ UDC 625.141-044.963 E. JUHASZ1* S. FISCHER2* 1*Dep. «Transport Infrastructure», Széchenyi István University, Egyetem tér 1., Győr, Hungary, 9026, tel. + 36 (96) 613 544, e-mail , ORCID 0000-0002-5544-3146 2*Dep. «Transport Infrastructure», Széchenyi István University, Egyetem tér 1., Győr, Hungary, 9026, tel. + 36 (96) 613 544, e-mail , ORCID 0000-0001-7298-9960 SPECIFIC EVALUATION METHODOLOGY OF RAILWAY BALLAST PARTICLES’ DEGRADATION Purpose. The most railway lines in the world have so called traditional ballasted superstructure. The authors think that it is important to learn about the process of ballast degradation. There are only two types of standardized laboratory test methods in the EU to assess railway ballast particle degradation and describe the rock physic characteristics, but are not suitable for modelling the railway stress-strain circumstances of ballast materials, and they particles. In this paper the authors represent some conclusions from their research that the authors experienced during their individual fatigue laboratory test and from new additional tests. With these kind of testing methods, the deterioration process of railway ballast particles can be assessed more realistic and precisely. Methodology and new directions. There are two types of laboratory tests which are presented in this article. The first one was performed by using a shear box with a special layer structure that is loaded by dynamic, pulsating force; while the second one was executed by using a 140 mm diameter HDPE tube with its original closing element that is loaded by ZD-40 machine. Findings and problems. There is a development after the R&D work made and published in 2014, in 2017 and 2018 years the ballast particle deterioration process is given according to more intermediate fatigue cycles with individual measurements that show more precise «picture» about the full particle degradation, i.e. breakage process. The authors give more accurate correlation functions between the calculated parameters and load cycles during fatigue. However, there are many factors in the test that need to be improved in the future. Therefore, the authors have discovered other additional tests. Originality. The most important goal of the authors that supplement the currently used regulation with new measurement methods. Practical value The authors’ developed and new methods may serve as a basis for a future instruction or regulation. The publishing of this paper was supported by EFOP 3.6.1-16-2016-00017 project. Keywords: individual laboratory test method; railway ballast material; particle degradation; breakage; dynamic fatigue test; static pressing test; CT equipment; 3-D image analysis Purpose For the railway transport the most widely used superstructure is the ballasted track [23, 24]. The ballast bed bears significant forces and plays important role in load carrying «chain». Each part of the track receives static and dynamic effects in different proportions [1, 2, 50, 52]. The forces and stresses do not transmit consistently in the «sleeper-ballast bed» interface, as well as «grain-grain» connections in the ballast bed. These kinds of effects are the following (without completeness):  dead weight loading (according to the authors’ analysis, it is negligible),  vehicle forces and effects (on perfect or quite perfect quality track),  previous geometric and/or structural features on defective track (defects of track geometry, Creative Commons Attribution 4.0 International doi: https://doi.org/10.15802/stp2019/171778 96 «hammering» of rails at rail joints, defects of welding…etc.) [1, 2, 4, 38, 39, 40, 41, 50, 52],  natural and environmental effects (freeze, melt, sunshine, rain, wind, flood, etc.),  effects at turnouts caused be railway vehicles [50, 52],  effects at level crossing caused by road vehicles,  effects of tamping machines’ hammers during operation,  other relevant effects (e.g. other vehicle effects, etc.) [0032, 0034]. The degradated ballasted track cause significant geometric changes that cause structural, stability and drainage problems. These problems could shorten the lifetime of the track even in a short term [1, 50, 51, 52]. In nowadays practice it is obvious aspect that required quality ballast [9, 13, 29, 30, 33, 34, 35, © E. Juhasz, S. Fischer, 2019 ISSN 2307–3489 (Print), ІSSN 2307–6666 (Online) Наука та прогрес транспорту. Вісник Дніпропетровського національного університету залізничного транспорту, 2019, № 3 (81) ЗАЛІЗНИЧНА КОЛІЯ ТА АВТОМОБІЛЬНІ ДОРОГИ 36, 37, 46, 47, 49] is achievable in requested quantity. It would be important to embed crushed stone materials with better rock physic properties as railway ballast bed. Using these ballast materials would also facilitate production, transportation, installation, operation and maintenance. In reality, the previous assumption is not evidence: the employed and developed laboratory testing methods by the authors and the MSZ EN 13450:2003 product standard [37] (in Hungary the Modification 4 in MÁV 102345/1995 PHMSZ [30]) can be suitable for redound and raising with the higher volumes of the LARB and MDERB. The developed testing method may be a proposal for the elaboration or modification of new assessment and measurement method and the revision of the values’ limits. There are two types of standardized laboratory test methods in the EU which could describe the rock physic characteristics of the railway ballast and determined in the MSZ EN 13450:2003 product standard [37]:  Los Angeles abrasion test (MSZ EN 10972:2010) [0021],  Micro-Deval abrasion test (MSZ EN 10971:2010) [0020]. These laboratory test methods are not suitable for modelling the railway loads in a real manner with the dynamic force and vibration [0035, 0037], but they can be absolutely useable for satisfy defining the abrasion characteristics of a given aggregate sample and for ensure the checking of the quality level. For the objective judgement of conformability special laboratory breakage test has to be used that consider the more real operation circumstances and stresses. The unique laboratory test method was developed in 2015 [17], because the standardized tests cannot consider the real breakage and abrasion (i.e. loads from vehicles and other effects). The results of the test were compared with the related regulation of MÁV (Hungarian Railways). The individual laboratory test helps to calculate the required time intervals of ballast screening. The authors research the theme’s extensive international literature. Foreign researchers are actively publishing in the research topic, so there is a comprehensive literature in different areas and different methods: laboratory tests; field tests; Creative Commons Attribution 4.0 Internati (...truncated)