scholarly journals DYNAMIC MODELLING OF HIGH SPEED BALLASTED RAILWAY TRACKS: ANALYSIS OF THE BEHAVIOUR

2016 ◽  
Author(s):  
Santos Sánchez-Cambronero ◽  
Inmaculada Gallego ◽  
Ana Rivas ◽  
Julián Lajara
Keyword(s):  
Numerical Model ◽  
High Speed ◽  
Dynamic Modelling ◽  
Dynamic Effect ◽  
Railway Track ◽  
Moving Loads ◽  
The Finite Element Method ◽  
Vertical Stiffness ◽  
Railway Line ◽  
Moving Train

The aim of the paper is to present a numerical model for a ballasted railway track that includes the dynamic effect of a moving train load and predicts the values of the vertical stiffness of the infrastructure. This model is therefore deemed to be a tool for the evaluation of the state of the track during service situations as well as a predictive model of the behaviour of the system. Consequently, it will be very useful when sizing the cross section of a new railway line is required.The main modelling tool is the finite element method. In regard to this, the application of damping elements to avoid the elastic wave reflection on the boundaries of the numerical domain will be studied. The proposed dynamic analysis consider the change in time of the value of the train load, but not the change in position along the tracks.In the end, a set of suggestions for the numerical model with moving loads will be summarize aiming for the mitigation of the unusual behaviour of the contact surface between the ballast and the sleepers.DOI: http://dx.doi.org/10.4995/CIT2016.2016.4218

scholarly journals Analysis of massive sulphate attack to cement-treated compacted soils

2020 ◽  
Vol 195 ◽  
pp. 01009
Author(s):  
Anna Ramon-Tarragona ◽  
Eduardo Alonso
Keyword(s):  
High Speed ◽  
Good Evidence ◽  
Railway Track ◽  
Active Volume ◽  
Sulphate Content ◽  
Compacted Soils ◽  
Cement Interface ◽  
Railway Line ◽  
Long Time ◽  
Sand And Gravel

The paper describes the heave experienced by two embankments providing access to a bridge located in a high-speed railway line. The compacted soil, a mixture of a low plasticity clay, sand and gravel, had a significant sulphate content (2 – 2.5%). The embankments received a reinforcing treatment by mixing the soil with cement in the proximity of the bridge abutments. In addition, a grid of grouting columns provided more stiffness to the embankments. The embankments experienced a fast heaving rate (around 4 mm/month) in the areas improved by cement mixing. Precision extensometers indicated that heave concentrated in the upper 6 – 8 m of the embankments. The sulphate content reduced sharply to 0.25% at increasing depth. No heave was detected in these deeper zones. The swelling was found to be associated with the development of thaumasite and ettringite minerals. The presence of clay, cement and sulphates in the compacted soils and the infiltration of water from rainfall events are ideal conditions for the growth of the mentioned minerals. Long-term tests performed on compacted samples provided a good evidence of the phenomena developing in situ. A chemical modelling of the mineral changes at the soil-cement interface provided an additional insight into the development of swelling, which could last for a long time (several years). Accordingly, it was decided to underpin the railway track and to excavate the upper active volume of the embankments. This solution went in parallel with train service, which was never interrupted.

scholarly journals Annoyance Based Vibro-Acoustic Comfort Evaluation of as Summation of Stimuli Annoyance in the Context of Human Exposure to Noise and Vibration in Buildings

2020 ◽  
Vol 12 (23) ◽  
pp. 9876
Author(s):  
Krzysztof Nering ◽  
Alicja Kowalska-Koczwara ◽  
Krzysztof Stypuła
Keyword(s):  
High Speed ◽  
Residential Building ◽  
Railway Track ◽  
Simultaneous Occurrence ◽  
Noise And Vibration ◽  
Noise Current ◽  
Railway Line ◽  
High Speed Trains ◽  
Acoustic Comfort ◽  
The City

This paper presents the issues of assessing the comfort of people staying indoors who are exposed to vibrations and material noise caused by vibrations of partitions like floors and walls (ground-borne noise). Current criteria in the evaluation of vibrational and acoustic comfort cannot be assessed in the context of the simultaneous occurrence of stimuli such as noise and vibration. Railway transport, including passenger and cargo transport, is becoming increasingly prevalent, and new railway lines are being planned for environmental reasons. Sometimes, there are changes in stimuli produced by existing railway lines. For example, high-speed trains appear on an old railway track. Such a situation appeared on the Central Railway Line in Poland, which is still used by old trains, yet its operator plans to raise their speed limits. The analysis of the problem of the simultaneous occurrence of stimuli presented in this paper was based on measurements performed in a residential building located near the Central Railway Main Line in the city Zawiercie. Noise and vibration as the analyzed stimuli in both cases meet comfort requirements, yet when exposure to two stimuli was considered, comfort may be at risk.

Tram track stiffness measurement based on the vision method

2019 ◽  
Vol 125 ◽  
pp. 45-52
Author(s):  
Seweryn Koziak ◽  
Rafał Melnik ◽  
Bartosz Firlik
Keyword(s):  
High Speed ◽  
Point Of View ◽  
Railway Track ◽  
Dynamic Interactions ◽  
Vertical Stiffness ◽  
Stiffness Measurement ◽  
Track Condition ◽  
Track Stiffness ◽  
Track Vertical Stiffness ◽  
The City

One of the main parameters characterizing properties of railway track is vertical stiffness. Provision of its appropriate value is crucial from the point of view of dynamic interactions occurring in a wheel-rail contact, what in turn translates into vehicle running behaviour and safety, passenger comfort, as well as further degradation of track condition. Track stiffness measurement is a cumbersome process requiring expensive equipment and can be carried out only if the line is closed. The following research is intended to estimate tram track vertical stiffness by means of vision method which can be performed during regular tram operation. Track deflections of tram line in the city of Poznan were carried out using high-speed camera and further used for vertical stiffness estimation.

INVESTIGATION INTO THE CALCULATION OF SUPERELEVATION DEFECTS ON CONVENTIONAL RAIL LINES

Transport ◽  
2012 ◽  
Vol 27 (3) ◽  
pp. 229-236 ◽  
Author(s):  
Inesa Gailienė
Keyword(s):  
High Speed ◽  
Great Influence ◽  
Railway Track ◽  
Lateral Acceleration ◽  
Essential Factor ◽  
Railway Line ◽  
Passenger Transportation ◽  
Heavy Haul ◽  
Train Speed ◽  
Conventional Rail

Railway curves have influence on train speed on a curve and/or wheel/rail interface. Additional forces that have to be compensated appear in the curves. The purpose of superelevation is to compensate acceleration emerging in the curve thus assuring comfortable passenger transportation and equal wearing of both rails. However, it is very difficult to calculate superelevation when designing and maintaining a railway track, because the estimation of actual train speed on the curves is very complicated. As we know, railway lines can be divided into conventional, high speed and heavy haul ones. As these lines are absolutely different, requirements for the installation and maintenance of the track may also differ. Conventional rail lines are the object of research discussed in this article. The speed of freight and passenger trains is different on conventional rail lines, which is an essential factor in determining superelevation. On the ground of scientific researches, the article analyzes and evaluates the factors influencing wheel/rail interface on the curves. The paper also deals with railway line curves, superelevation and uncompensated lateral acceleration. The article presents the method used in Lithuania for calculating superelevation in the railway curves and analyzes calculation defects. For research purposes, analytical and statistical methods have been used. The obtained results have shown that actual superelevation in the researched curves does not match the calculated one. The calculations and obtained results of superelevation depend on how average train speed in the curves is estimated and used for calculations. As most of the results show that even small variations in the curve have a great influence on track/vehicle behaviour, it is necessary to find more precise methods for calculating superelevation, evaluating actual train speed and considering permissible uncompensated lateral acceleration in the curves.

scholarly journals Railway deformation detected by DInSAR over active sinkholes in the Ebro Valley evaporite karst, Spain

2015 ◽  
Vol 15 (11) ◽  
pp. 2439-2448 ◽  
Author(s):  
J. P. Galve ◽  
C. Castañeda ◽  
F. Gutiérrez
Keyword(s):  
High Speed ◽  
Ground Deformation ◽  
Transport Infrastructure ◽  
Railway Track ◽  
Ebro Valley ◽  
Railway Line ◽  
Synthetic Aperture Radar Interferometry ◽  
Evaporite Karst ◽  
Railway Tracks ◽  
Deformation Processes

Abstract. Subsidence was measured for the first time on railway tracks in the central sector of Ebro Valley (NE Spain) using Differential Synthetic Aperture Radar Interferometry (DInSAR) techniques. This area is affected by evaporite karst and the analysed railway corridors traverse active sinkholes that produce deformations in these infrastructures. One of the railway tracks affected by slight settlements is the Madrid–Barcelona high-speed line, a form of transport infrastructure highly vulnerable to ground deformation processes. Our analysis based on DInSAR measurements and geomorphological surveys indicates that this line shows dissolution-induced subsidence and compaction of anthropogenic deposits (infills and embankments). Significant sinkhole-related subsidence was also measured by DInSAR techniques on the Castejón–Zaragoza conventional railway line. This study demonstrates that DInSAR velocity maps, coupled with detailed geomorphological surveys, may help in the identification of the railway track sections that are affected by active subsidence.

scholarly journals Permissible Values of the Dynamic Impact of the Rolling Stock on the Railway Track in the Case of Axle Load Increase

2021 ◽  
pp. 15-23
Author(s):  
О. M Patlasov ◽  
Y. M Fedorenko
Keyword(s):  
Dynamic Effect ◽  
Field Measurements ◽  
Experimental Tests ◽  
Railway Track ◽  
Rolling Stock ◽  
Actual State ◽  
Dynamic Force ◽  
Dynamic Impact ◽  
Railway Line ◽  
The Impact

Purpose. The study is aimed at determining experimentally the values of the parameters characterizing the dynamic effect of rolling stock on the railway track, substantiating the maximum permissible (limiting) values. Methodology. To investigate the interaction between the track and the rolling stock, the devices to record various physical processes were installed on the experimental sections. The devices were installed in 8 sections along the outer railway line. To establish the actual state of the track, field measurements were carried out in accordance with the Program and research methodology. Findings. According to the results of experimental tests of the impact on the track, it was revealed that the average vertical loads, and, accordingly, the average vertical deformations, under the cars with an axle load of up to 25 tf/axle are higher than that under the cars with an axle load of up to 23.5 tf/axle by 8 percent. The maximum vertical loads under the cars with an axle load of 25 tf/axle exceeded the average loads by 10.0 tf, and under the cars with an axle load of up to 23.5 tf/axle exceeded the average values by 12.8 tf. During the tests, no cars were found in which the vertical dynamic force exceeds 20 tf, and the horizontal force exceeds 10 tf. Therefore, the norms of permissible dynamic impact can be taken in accordance with the Regulations on Preventive Maintenance and Repair Track Work on the Railways of Ukraine. Originality. The authors conducted a study to assess the dynamic characteristics of the interaction of track and rolling stock, in particular the stresses in the edges of the rail base, vertical and horizontal forces from the wheels of rolling stock. Practical value. On the basis of the results obtained, it is possible to estimate the permissible values of the dynamic effect of the rolling stock on the railway track to substantiate the need to change the standards for the material consumption of the track superstructure and labor. In turn, this will make it possible to plan the repair and track periods more economically and according to the actual indicators of the state of the track superstructure.

Wu Guang High-Speed Rail Track Irregularity Power Spectrum Analysis

2014 ◽  
Vol 638-640 ◽  
pp. 1224-1228 ◽  
Author(s):  
Ji Yang Li ◽  
Lin Ya Liu ◽  
Dong Hua Kou
Keyword(s):  
Power Spectrum ◽  
High Speed ◽  
Railway Track ◽  
High Speed Rail ◽  
Track Geometry ◽  
Railway Line ◽  
Spectrum Density ◽  
Track Irregularity ◽  
Parameter Values ◽  
Geometry Inspection

Irregularity is the locomotive and the main excitation source of vibration, is directly related to the smooth running of the train, safety and comfort, is to control the maximum operating speed of the train one of the main factors. The statistic specimen was collected by track geometry inspection car from Wuhan-Guangzhou high-speed rail. Based on the stationarity test of the specimen, Fast Fourier Transform (FFT) method was used to evaluate the spectrum of the whole specimen space. The power spectrum density (PSD) and related functions of track irregularity were obtained by MATLAB program. We analyzed it by comparing the fitting curve of the national speed lines and fitting curve of Qinhuangdao-Shenyang dedicated passenger railway line, by comparison, the Wuhan-Guangzhou high-speed railway track irregularity is much better than the national speed lines and Qinhuangdao-Shenyang dedicated passenger railway line. The parameter values of PSD fitting curve for track irregularity are obtained by the nonlinear curve-fitting algorithm in the least-squares sense, which has referencing value to maintenance high-speed rail.

Numerical Model Updating Technique for Estimating Load Carrying Capacities of High Speed Railway Bridges

2016 ◽  
Vol 106 (8) ◽  
pp. 490-497
Author(s):  
Dong-Uk PARK ◽  
Jae-Bong KIM ◽  
Nam-Sik KIM ◽  
Sung-Il KIM
Keyword(s):  
Numerical Model ◽  
High Speed ◽  
Model Updating ◽  
High Speed Railway ◽  
Railway Bridges ◽  
Load Carrying

scholarly journals Multiview deep learning based on tensor decomposition and its application in fault detection of overhead contact systems

2021 ◽  
Author(s):  
Xuewu Zhang ◽  
Yansheng Gong ◽  
Chen Qiao ◽  
Wenfeng Jing
Keyword(s):  
High Speed ◽  
Tensor Decomposition ◽  
Detection Methods ◽  
Detection Accuracy ◽  
Feature Maps ◽  
Training Time ◽  
Detection Model ◽  
Railway Line ◽  
Result Show ◽  
Deep Layers

AbstractThis article mainly focuses on the most common types of high-speed railways malfunctions in overhead contact systems, namely, unstressed droppers, foreign-body invasions, and pole number-plate malfunctions, to establish a deep-network detection model. By fusing the feature maps of the shallow and deep layers in the pretraining network, global and local features of the malfunction area are combined to enhance the network's ability of identifying small objects. Further, in order to share the fully connected layers of the pretraining network and reduce the complexity of the model, Tucker tensor decomposition is used to extract features from the fused-feature map. The operation greatly reduces training time. Through the detection of images collected on the Lanxin railway line, experiments result show that the proposed multiview Faster R-CNN based on tensor decomposition had lower miss probability and higher detection accuracy for the three types faults. Compared with object-detection methods YOLOv3, SSD, and the original Faster R-CNN, the average miss probability of the improved Faster R-CNN model in this paper is decreased by 37.83%, 51.27%, and 43.79%, respectively, and average detection accuracy is increased by 3.6%, 9.75%, and 5.9%, respectively.

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