Field study using additional rails and an approach slab as a transition zone from slab track to the ballasted track

2017 ◽  
Vol 232 (4) ◽  
pp. 970-978 ◽  
Author(s):  
H Heydari-Noghabi ◽  
JA Zakeri ◽  
M Esmaeili ◽  
JN Varandas
Keyword(s):  
Transition Zone ◽  
Dynamic Behavior ◽  
Field Tests ◽  
Field Measurements ◽  
Sudden Increase ◽  
Transition Zones ◽  
Slab Track ◽  
Railway Line ◽  
Approach Slab ◽  
Ballasted Track

An abrupt change in the stiffness of railway tracks at the junction between slab track and ballasted track causes increased dynamic loads, asymmetric settlements, damage of track components, and, consequently, increased maintenance costs. Due to this, a transition zone is usually built at the junction between the ballasted and the ballastless tracks to reduce the aforementioned problems. One of the methods suggested as a transition zone in these areas is to use a combination of an approach slab and additional rails. This study evaluates the dynamic behavior of this type of transition zone using field tests and also compares its performance with a transition zone built only with an approach slab. Hence, in the Tehran–Karaj railway line, two types of transition zones were constructed: one including only the approach slab and the other one including additional rails and an approach slab. Then, by conducting some field tests, the dynamic behavior of the track in these two types of transition zones was examined. The results of the field measurements show that for the analyzed case study, at the combined transition zone with additional rails and an approach slab, instead of a sudden increase in rail displacements from the slab track to the ballasted track (i.e. by 53%), initially, in the first part of the transition zone (with additional rails and an approach slab), the deflections increase by an average of 31%, and then in the second part of the transition zone (with additional rails only) the deflections increase additionally by 11%.

scholarly journals THE INFLUENCE OF TRAIN RUNNING DIRECTION AND TRACK SUPPORTS POSITION ON THE BEHAVIOUR OF TRANSITION ZONES

2016 ◽  
Author(s):  
Roberto Sañudo Ortega ◽  
Marina Miranda manzanares ◽  
Valeri Markine ◽  
LUIGI DELL'OLIO
Keyword(s):  
Finite Elements ◽  
Separation Zone ◽  
Maintenance Costs ◽  
Transition Zones ◽  
Slab Track ◽  
Railway Line ◽  
Ballasted Track ◽  
Different Types ◽  
Vertical Displacements ◽  
Separation Zones

Different types of track infrastructure can be found along railway lines. Separation zones between these different types of structures are the source of a lot of problems. Transition zones on a railway line represent a gradual solution for the problems between conventional railway structure and singular structures located at different points along the line. The different nature, positioning and geometry used with the materials generate changes in the stiffness on both sides of these singular zones leading to an increase in wear and a loss of geometry, with the associated maintenance costs. This article describes the use of mathematical modelling to represent the behaviour of these zones as a function of train running direction and track supports. Available research into transition zones has not studied these separation points where high increases in load are generated for very short periods of time. Finite elements are used to model two types of track (conventional ballasted track and slab track), using a vehicle to dynamically simulate the behaviour in these zones as a function of train running direction and the position of track supports. The magnitudes analysed were the vertical stresses and the vertical displacements under the sleepers and the supports in both types of structure. The results show increased stresses at the separation zone between both structures which varied in magnitude and position depending most of track supports’ location than the train running direction.DOI: http://dx.doi.org/10.4995/CIT2016.2016.4073 

scholarly journals Qualitative Prediction Model for Dynamic Behavior of Ballasted Tracks

2020 ◽  
Vol 10 (18) ◽  
pp. 6258
Author(s):  
Jung-Youl Choi ◽  
Sun-Hee Kim
Keyword(s):  
Dynamic Response ◽  
Prediction Model ◽  
Dynamic Behavior ◽  
Field Measurement ◽  
Field Measurements ◽  
Bending Stress ◽  
Qualitative Prediction ◽  
Proposed Model ◽  
Ballasted Track ◽  
Two Degree Of Freedom

Theoretical, experimental, analytical, and statistical evaluations were performed to predict and assess the dynamic behavior of a ballasted track, such as the track support stiffness, track impact factor, or dynamic wheel–rail forces. Field measurements were then performed to evaluate the dynamic behavior of the ballasted track and its components. A qualitative prediction model was then developed to predict and assess track performance as a function of dynamic wheel-rail force and variation in track support stiffness. The developed two-degree-of-freedom dynamic track model can define the rail pad and ballast stiffness ranges based on designed and measured values. Using the proposed model, qualitative analysis results are presented as a discrete space of various track responses and parameters, rather than as single values. The proposed model was then validated using field measurements, which demonstrated that the proposed model predicted the vertical rail displacement and rail bending stress within approximately 2–5% of the obtained field measurements. Overall, the developed qualitative prediction model allows the dynamic response of in-service ballasted tracks to be estimated as a function of the rail pad and ballast stiffness using only a simple field measurement.

scholarly journals Ballast trough on ground as an alternative to slab track

2016 ◽  
Vol 2016 (4) ◽  
pp. 40-45
Author(s):  
Igor Gisterek
Keyword(s):  
Economic Benefits ◽  
Human Environment ◽  
Slab Track ◽  
Railway Line ◽  
Ballasted Track ◽  
The Subject ◽  
Development Countermeasures ◽  
Track Slab ◽  
Excessive Noise

Due to an increase in expectation concerning human environment and increase in comfort of habitat and workplace, a rising role of means and measures protecting from excessive noise and vibrations can be noted. To meet the requirements of sustainable development, countermeasures should result in long-lasting social and economic benefits. The paper deals with the subject of noise and vibration protection of people and structures along a railway line. A system consisting of concrete trough on ground, containing ballasted track was proposed and erected. This structure was compared with classic and slab track. Keywords: Ballast trough; Ballasted track; Slab track.

scholarly journals Wheel Flats in the Dynamic Behavior of Ballasted and Slab Railway Tracks

2021 ◽  
Vol 11 (15) ◽  
pp. 7127
Author(s):  
Cecilia Vale
Keyword(s):  
Dynamic Behavior ◽  
Vertical Displacement ◽  
Numerical Approach ◽  
Hertzian Contact ◽  
Dynamic Force ◽  
Slab Track ◽  
Regulatory Limits ◽  
Continuous Slab ◽  
Ballasted Track ◽  
Wheel Flat

Wheel flats induce high-impact loads with relevance for the safety of the vehicle in operation as they can contribute to broken axles, hot axle boxes, and damaged rolling bearings and wheels. The high loads also induce damage in the track components such as rails and sleepers. Although this subject has been studied numerically and experimentally over the last few years, the wheel flat problem has focused on ballasted tracks, and there is a need to understand the phenomena also for slab tracks. In this research, a numerical approach was used to show the effects of the wheel flats with different geometric configurations on the dynamic behavior of a classical ballasted track and a continuous slab track. Several wheel flat geometries and different vehicle speeds were considered. The nonlinear Hertzian contact model was used because of the high dynamic variation of the interaction of the load between the vehicle and the rail. The results evidenced that, for the same traffic conditions, the dynamic force was higher on the slab track than on the ballasted one, contrary to the maximum vertical displacement, which was higher on the ballasted track due to the track differences regarding the stiffness and frequency response. The results are useful for railway managers who wish to monitor track deterioration under the regulatory limits.

Dynamic performance of continuous railway bridges: Numerical analyses and field tests

2017 ◽  
Vol 232 (3) ◽  
pp. 936-955 ◽  
Author(s):  
Hongye Gou ◽  
Xiaoyu Shi ◽  
Wen Zhou ◽  
Kai Cui ◽  
Qianhui Pu
Keyword(s):  
Dynamic Behavior ◽  
Dynamic Performance ◽  
Field Tests ◽  
Field Measurements ◽  
Element Model ◽  
Main Beam ◽  
Bridge Structure ◽  
Railway Bridges ◽  
Running Safety ◽  
The One

In this study, a refined finite element model was built that represented the structural and mechanical properties of railway bridges. A coupled vehicle–bridge vibration model was established to simulate the dynamic behavior of the bridge under moving trains. Field tests were then conducted to determine the free vibration characteristics as well as the strain, displacement, and acceleration of the bridge structure under trains moving at different speeds and braking at a specified position from a set speed. The dynamic response of the bridge was found to increase with the train speed, but the main beam of the bridge was more affected by a train braking than the one passing over it. Both the bridge and vehicle were found to meet the relevant requirements for safe design and operation, with the train exhibiting good running safety and smoothness, and the bridge structure showing sufficient stiffness and dynamic performance. Based on the field measurements and analytical modeling, it can be concluded that the use of appropriate equipment and the selection of a suitable layout for the sensors permit the assessment of the dynamic behavior of the bridges from vibration measurements. This indicates the potential for the continuous health monitoring of the railway bridges that may be sensitive to the vehicle–bridge interaction.

scholarly journals Analysis of Dynamic Characteristics of Deformed Concrete Slab Track on Transition Zone in High-Speed Train Line According to Train Speeds

2020 ◽  
Vol 10 (20) ◽  
pp. 7174
Author(s):  
Sungbum Park ◽  
Ja Yeon Kim ◽  
Jongwon Kim ◽  
Sehee Lee ◽  
Kook-Hwan Cho
Keyword(s):  
Numerical Analysis ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Concrete Slab ◽  
Field Tests ◽  
Analysis Model ◽  
Transition Zones ◽  
Slab Track ◽  
Speed Range ◽  
Train Speed

A concrete track, such as Rheda 2000 is commonly used in high-speed railways in Korea, Germany, China, etc., to enhance the operational safety of trains and to reduce the maintenance costs. However, when settlement of embankment or a crack in the concrete slab track occurs, the durability of the concrete track deteriorates significantly. Transition zones are considered to be vulnerable and are often deformed in railway embankments. The characteristics of track support stiffness and stresses on the rail in a deformed section are different from those in an undeformed section. In this study, a field measurement and numerical analysis were carried out to identify the dynamic response on transition zones where the track is deformed. A numerical analysis model was built to simulate the deformed concrete slab track, and it was compared with measured data from field tests for verification. The field tests to measure the stresses on the rail were performed in a train speed range from 280 to 300 km/h. According to the numerical analysis, the dynamic characteristics of the track varied with train speeds, which were then compared with the allowable stresses of the concrete slab track.

scholarly journals Underwater Holographic Sensor for Plankton Studies In Situ Including Accompanying Measurements

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4863
Author(s):  
Victor Dyomin ◽  
Alexandra Davydova ◽  
Igor Polovtsev ◽  
Alexey Olshukov ◽  
Nikolay Kirillov ◽  
...  
Keyword(s):  
World Ocean ◽  
Field Tests ◽  
Field Measurements ◽  
Measuring Systems ◽  
Water Turbidity ◽  
Background Data ◽  
Average Size ◽  
Size Dispersion

The paper presents an underwater holographic sensor to study marine particles—a miniDHC digital holographic camera, which may be used as part of a hydrobiological probe for accompanying (background) measurements. The results of field measurements of plankton are given and interpreted, their verification is performed. Errors of measurements and classification of plankton particles are estimated. MiniDHC allows measurement of the following set of background data, which is confirmed by field tests: plankton concentration, average size and size dispersion of individuals, particle size distribution, including on major taxa, as well as water turbidity and suspension statistics. Version of constructing measuring systems based on modern carriers of operational oceanography for the purpose of ecological diagnostics of the world ocean using autochthonous plankton are discussed. The results of field measurements of plankton using miniDHC as part of a hydrobiological probe are presented and interpreted, and their verification is carried out. The results of comparing the data on the concentration of individual taxa obtained using miniDHC with the data obtained by the traditional method using plankton catching with a net showed a difference of no more than 23%. The article also contains recommendations for expanding the potential of miniDHC, its purpose indicators, and improving metrological characteristics.

scholarly journals Petiole-Lamina Transition Zone: A Functionally Crucial but Often Overlooked Leaf Trait

Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 774
Author(s):  
Max Langer ◽  
Thomas Speck ◽  
Olga Speck
Keyword(s):  
Transition Zone ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Body Plan ◽  
The Body ◽  
Vascular Bundles ◽  
Cross Sectional ◽  
Thin Sections ◽  
Transition Zones ◽  
The Cross

Although both the petiole and lamina of foliage leaves have been thoroughly studied, the transition zone between them has often been overlooked. We aimed to identify objectively measurable morphological and anatomical criteria for a generally valid definition of the petiole–lamina transition zone by comparing foliage leaves with various body plans (monocotyledons vs. dicotyledons) and spatial arrangements of petiole and lamina (two-dimensional vs. three-dimensional configurations). Cross-sectional geometry and tissue arrangement of petioles and transition zones were investigated via serial thin-sections and µCT. The changes in the cross-sectional geometries from the petiole to the transition zone and the course of the vascular bundles in the transition zone apparently depend on the spatial arrangement, while the arrangement of the vascular bundles in the petioles depends on the body plan. We found an exponential acropetal increase in the cross-sectional area and axial and polar second moments of area to be the defining characteristic of all transition zones studied, regardless of body plan or spatial arrangement. In conclusion, a variety of terms is used in the literature for describing the region between petiole and lamina. We prefer the term “petiole–lamina transition zone” to underline its three-dimensional nature and the integration of multiple gradients of geometry, shape, and size.

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