•Summary and comparison of ballast standards in different countries.•Promising future ballast technologies are discussed.•Ballast qualification considering different material types and local ...geologies.
The properties of railway ballast material are affected by the local geologies and climatic environments from which the parent rock is sourced. These factors can make it challenging to select the most appropriate material for railway applications. To address this issue, this paper first reviews the means of ballast selection in complex environments across the world. The selection criteria for ballast materials are compared and test methods for ballast quality quantification are summarised. Next, ballast parent rock types and the implications of mining approaches are discussed, before analysing ballast morphology with respect to ballast size and shape. Then ballast petrography is reviewed with a focus on the effect of mineral composition on performance. Finally, some promising future ballast technologies are discussed with a focus on environmental performance. These include recycled ballast, asphaltic materials, steel slag and ballast gluing. The review shows that regarding ballast selection means and criteria, the number and type of quantitative indicators varies greatly between countries. In particular there are divergences in test methods and quantitative indicators for ballast quality considering material types and local geologies. Suggested future research directions are proposed, such as the effect of tamping and dynamic track stabilisation on ballast properties.
•The weathering effects of LD slag as ballast have been overlooked.•Freeze–thaw cycles revealed excellent durability and strength for LD slag.•To benchmark the performance of LD slag, basalt and ...gneiss are investigated.•Chemical weathering exerts dominant control on the performance of ballasts.•The use of LD slag as ballast represents a promising waste solution for the steel sector.
As nonrenewable natural aggregates with acceptable geotechnical properties become scarce, costly, and entail negative environmental impacts, the study of alternatives remains a first-order challenge for sustainable railway design. This paper focuses on the physical and chemical weathering effects of the industrial byproduct Linz–Donawitz (LD) slag as a ballast material. For this purpose, 75 freeze–thaw (F-T) and 40 sulfate soundness (SS) cycles were carried out on the byproduct. We present a series of laboratory experiments involving particle characteristics, durability and strength for different F-T and SS cycles. To benchmark the performance of LD slag, we also performed our experiments on two natural aggregates: gneiss and basalt. Our main findings reveal that: (i) the shape of LD slag ballast and its particle size distribution are unnafected by the F-T and SS cycles, (ii) the basalt exhibits higher magnitudes of fouling after SS cycles, (iii) losses in Los Angeles abrasion and shock resistance were much more pronounced in SS tests for all ballast materials, (iv) LD slag is more resistant and less susceptible to the degrading effects of freezing and thawing, (v) point load tests indicate that the loss of resistance of basalt is small compared to that of gneiss, (vi) the byproduct showed a decrease in strength of 87% after 40 SS cycles, suggesting that chemical weathering exerts a dominant control on the performance of LD slag. The findings are relevant to elucidate the physical and chemical weathering effects of LD slag and to promote its sustainable use.
Across countries, associations and institutions publish technical standards for railway ballast, however it is observed that those norms have differences when compared to each other. Each one of them ...has its particularity, varying according to the stone materials available in their countries, axle load and climate. In that sense, it is still a challenge to establish specific guidelines for the properties of the ballast layer. Recently, several techniques for acquisition, image analysis and particle scanning have been developed, either in 2D or in 3D. Those techniques vary from the use of pachymeter to the use of sophisticated scanners. This research seeks to evaluate, through laboratory tests, the evolution of the particle shape parameters through 3D scanning and the level of degradation of the steel slag when subjected to stresses close to those experienced in freight transport railways. Based on the performed tests and the obtained results, the authors recommend for a railway pavement subjected to a load of 32.5 t/axle and composed of steel aggregates used as ballast, a granulometric distribution with uniformity coefficient 1.5 ≤ Cu ≤ 1.6 (AREMA n. 4) and particles with: 0.625 ≤ Elongation ≤ 0.999, 0.567 ≤ Flatness ≤ 0.995, 0.475 ≤ Aspect ≤ 0.969 and 0.825 ≤ Ellipsoidness ≤ 0.957. These specifications enable a good performance of the ballast layer. In addition, the results found contribute to the understanding of siderurgic aggregate behavior under cyclic loading conditions.
The quality of ballast materials is an important criterion in railway track maintenance management systems. Although various studies have been made on the characteristics of ballast aggregates and ...ballast mechanical behaviours, making an optimal decision on the selection of appropriate ballast materials is still a serious challenge in the railway industry. It indicates a need for an integrated ballast quality index which could help to ensure improved cost-effectiveness of track maintenance. In response to this need, the mechanical, physical and environmental properties of the ballast were categorised and weighted based on their level of influences on the ballast overall conditions. Consequently, a ballast quality/condition index was developed as a function of the influencing parameters. To examine the practicability and applicability of the developed method/index, three types of ballast materials were taken from different sources and their quality was evaluated and discussed using the new index. Through illustrating the effectiveness of the new index in evaluation of ballast materials, it was shown that the new index can play a role to allocate an optimal ballast material quality and improve cost-effectiveness of the current maintenance by providing the ability to optimise ballast maintenance planning.
Purpose. There are specific, standardized laboratory test methods to assess railway ballast particle degradation; they are the Los Angeles (EN 1097-2) and the Micro-Deval abrasion (EN 1097-1) tests. ...These testing methods can’t take into consideration the real railway stress-strain circumstances of ballast materials, and they particles. In this paper the authors represent a specific laboratory fatigue breakage test of railway ballast materials. With this kind of testing method, the deterioration process of railway ballast particles can be assessed more realistic and precisely. Methodology. A special layer structure is built-up with elastic sublayer system and 30 cm thick ballast samples (from two different type andesite base rocks) that is loaded by dynamic, pulsating forces. Particle size distribution functions have to be recorded before and after a more million cycle fatigue test, but intermediate measurements are also executed. The measured data should be processed, and different parameters have to be calculated that are offered by international literature and researches. The test doesn’t consider the particle breakage due to hand-made and machine-made tamping, but it can simulate particle degradation due to more years’ railway traffic in laboratory circumstances. Findings. 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 precise correlation functions between the calculated parameters and load cycles during fatigue. Originality. The paper summed up the results of a specific developed laboratory test method for assessment of the breakage process of railway ballast particles according to two different railway ballast materials from andesite base rocks. Practical value. The results help with the calculation of approximate time interval of required ballast screening (cleaning) work in the future. This research is supported by the ÚNKP-17-4 New National Excellence Program of Ministry of Human Capacities.
Мета. Існують спеціальні стандартизовані методи лабораторних випробувань для оцінки руйнування частинок залізничного баластного шару – це випробування на стирання Лос-Анджелес (EN 1097-2) і Мікро-Деваль (EN 1097-1). Ці методи випробувань не враховують реальні умови напруженої деформації залізничних баластних матеріалів. Основною метою роботи є спеціальне лабораторне випробування на утомне руйнування залізничних баластних матеріалів. Такий метод випробування дозволяє більш реалістично і точно оцінити процес зносу часток матеріалу залізничного баластного шару. Методика. Спеціальну шарувату структуру, укріплену пружним нижнім шаром і баластними зразками товщиною 30 см (із двох різних порід андезитового щебеню), навантажують динамічними, пульсуючими силами. Слід записати функції розподілу розмірів часток до і після проведення більше ніж мільйона тестів на циклічну втому, а також виконати проміжні вимірювання. Потрібно опрацювати виміряні дані й розрахувати різні параметри, запропоновані в міжнародних наукових дослідженнях. Випробування не враховує руйнування часток внаслідок механічного чи ручного підбивання баласту, але дозволяє в лабораторних умовах імітувати руйнування часток від багаторічної дії залізничного руху. Результати. Після науково-дослідних і дослідно-конструкторських розробок руйнування баластного шару в 2014 році було опубліковано наукове дослідження. В 2017–2018 роках дослідження процесу руйнування часток баласту були представлені з урахуванням більш складних циклів навантаження, які мали індивідуальне оцінювання. Це дає більш точне уявлення про повне пошкодження часток баластного матеріалу, тобто про процес руйнування. Автори подають уточнені кореляційні функції між розрахунковими параметрами й циклами навантаження під час випробувань на втому. Наукова новизна. У цій роботі підсумовані результати розробленого лабораторного методу випробувань для оцінки процесу руйнування часток баластного матеріалу залізничного полотна із двох різних порід андезитового щебеню. Практична значимість. У подальшому результати можуть бути використані для обчислення приблизного часового інтервалу, необхідного для виконання робіт із очищення баласту. Це дослідження виконане відповідно до національної програми вдосконалення ÚNKP-17-4 Міністерства можливостей людини.
In this study, the durability of railway ballast material is investigated by magnesium sulfate soundness tests. Two types of ballast aggregates, which are produced from basaltic rocks and currently ...used as railway ballast in such high speed railway routes in Turkey, are investigated regarding their resistance against freezing–thawing (FT) and traffic loads. Firstly, the mineralogical and physico-mechanical properties of rocks are determined. Then the degradation of investigated ballast aggregates is determined by magnesium sulfate soundness and Los Angeles abrasion (LAA) tests. The natural FT effects are simulated by magnesium sulfate soundness tests up to 40 cycles, whereas the traffic loads are represented by LAA tests up to 3000 revolutions. The ballast fouling that leads to such problems are also investigated within the scope in the present study. The degree of ballast fouling is quantified as fouling index (FI) which is determined using the crushed particles generated after LAA tests. It is concluded from laboratory studies that rock properties considered are considerably influenced by simulated FT cycles. It is also achieved from the laboratory studies that magnesium sulfate soundness and Los Angeles abrasion tests are good indicators to clarify the fragmentation mechanism of the ballast aggregate in laboratory scale. In conclusion several empirical formulas are developed to predict LAA and FI for each rock type. The proposed empirical formulas could be utilized as a pre-design tool for new railway routes in design stage provided that the investigated ballast aggregates are considered.
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.
Мета. Більшість залізничних ліній у світі мають так звану традиційну верхню будову колії з баластним шаром. На думку авторів, для гарантування безпеки руху важливо вивчити процес руйнування баластного шару. У ЄС існує тільки два типи стандартних методів лабораторних випробувань для оцінки ступеня руйнування часток залізничного баластного шару й описання їх фізичних характеристик. Але вони не придатні для моделювання напружено-деформованого стану залізничних баластних матеріалів і їх часток. У цій статті автори представляють методи випробувань, за допомогою яких процес руйнування залізничних часток баласту можна оцінити більш реалістично й точно. Ці методи базуються на висновках із досліджень, індивідуальних лабораторних випробувань на втому, а також із додаткових випробувань. Методика. У роботі подано два типи лабораторних випробувань. Перший був виконаний із використанням зсувної коробки зі спеціальною шаруватою структурою, яка навантажена динамічною, пульсуючою силою. Другий тип – із використанням труби з поліетилену високої щільності діаметром 140 мм з оригінальною запірною деталлю, навантаженою машиною ZD–40. Результати. Після науково-дослідних розробок, проведених і опублікованих у 2014 році, спостерігається розвиток методів оцінки руйнування баластного шару. У 2017 й 2018 роках під час випробувань руйнування часток баласту було здійснено з більшими проміжними циклами втоми та окремими вимірами, які більш точно показують повне руйнування часток, тобто процес руйнування. Проведено кореляцію між розрахунковими параметрами й циклами навантаження на втому. Однак під час випробування залишається багато факторів, які потребують поліпшення. Тому автори описують інші додаткові тести. Наукова новизна. У роботі запропонована вдосконалена методика оцінки руйнування баластного шару залізничної колії, яка дає більш точні результати порівняно з традиційними методами вимірювань. Практична значимість. Методи, розроблені авторами можуть служити основою для складання нових інструкцій або правил. Публікація цієї статті була підтримана проектом EFOP 3.6.1-16-2016-00017.
Many industrial plants have railway lines that must support low-speed heavy haul freight traffic. This type of special haulage, such as pig iron torpedo ladles or heavy cisterns, may cause ...substantial settlement of the track foundations and require suitable sleeper and ballast design that allows these elements to uniformly transmit axle loads to the ground.
In this study, we develop a failure analysis of a railway track used for transporting heavy haul industrial freight. The aim of the study is to describe the method with which this type of failure should be analyzed. We develop a specific case, establishing the causes of failure and offering guidelines for improving the design and upkeep the sleepers and ballast on which the tracks are laid. The ultimate aim is to offer guidance to the forensic engineer on the tests and variables to analyze with regard to the failure of railway track foundations.
This article deals with finite-element (FE) modelling of the reinforcing effect of the geosynthetic material used in the construction of a ballasted track. Various different designs of geosynthetic ...material are studied and their reinforcing effects are evaluated in terms of the total settlement reduction. Three-dimensional FE models of the reinforced railway superstructure are compared to a reference FE model with no reinforcement. Each geosynthetic material is modelled respecting its material properties, and the interaction with the ballast material is simulated according to its primary function. A clear distinction in the modelling of the interaction with the ballast material is made between geogrids and the remaining geosynthetics. A new approach to model the reinforcing effect of a geogrid is proposed and evaluated by FE analysis. The results of numerical modelling are compared to those of experiments conducted using an experimental box instrumented with one half of an instrumented concrete sleeper. Different types of geosynthetics were used to reinforce the ballast material, and the settlement reduction was measured using linear variable differential transformer (LVDT) sensors. The proposed FE models enable quick evaluation of the reinforcing effect of a given geosynthetic and comparison to other possible solutions in terms of the total settlement reduction. Other design possibilities (e.g. the use of reinforcing geosynthetics in several layers) are briefly discussed, too.
PDF
