scholarly journals The problems of arising vertical irregularities in operating railway track

2016 ◽  
Vol 2016 (2) ◽  
pp. 9-22 ◽  
Author(s):  
Włodzimierz Andrzej Bednarek
Keyword(s):  
Load Transfer ◽  
Vertical Plane ◽  
Railway Track ◽  
Geometrical Parameters ◽  
Track Structure ◽  
Additional Increase ◽  
Unloaded State ◽  
Ballast Track ◽  
Track Stiffness ◽  
Railway Sleeper

Arising during railway track structure operating the geometrical irregularities of track in vertical plane are the additional sources of interaction between the trains and track. These irregularities have got an unintentional character (arising in random way during track operating, e.g. irregularities in track, change of track geometrical parameters or inhomogeneity of track support) and intentional character (arising e.g. during railway track lifting by VSS plate). The unintentional irregularity causes among other things an additional increase of deflections and stresses in track structure elements, which lead to failures and wear of track elements. Such arising the longitudinal irregularity in track is the reason for various forms of contact between sleeper and ballast. Track stiffness in unloaded state (without forces from trains) causes that the sleepers in various ways rest on the ballast. The analysis of load transfer from wheel by rail to the railway sleeper allows for visualizing the effects of such irregularity for railway track. Furthermore a shape of arising irregularity causes the decrease of train wheel traction efficiency understanding as the degree of its tractive adhesion utilization resulting from static loads. In paper an experimental analysis of arising irregularity in CWR track during its operating is enclosed.

scholarly journals Full-Scale Field Experimental Investigation on the Intended Irregularity of CWR Track in Vertical Plane

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7477
Author(s):  
Włodzimierz Andrzej Bednarek
Keyword(s):  
Static Load ◽  
Optical Measurement ◽  
Vertical Plane ◽  
Railway Track ◽  
Support Condition ◽  
Static Loads ◽  
Static And Dynamic Analysis ◽  
Field Investigations ◽  
Railway Sleeper ◽  
Locomotive Wheels

The purpose of the following paper is to present the author’s experimental field investigations of a jointless railway track subjected to a generated imperfection and analysis of track response to applied static loads. An optical measurement system, Pontos, was used for the static and dynamic analysis of the track’s deflections in 3D. The investigations allow us to recommend a direct application of this system for the non-contact measurement, visualization and analysis of simulated defects in the jointless track, as presented by the author. It is stated that simulation of an effect called the hanging sleeper, a short irregularity in the railway track with the initial parameters provided (a gap and a length of irregularity), is possible. The proposed method, based on the measurement in the loaded track (a static load from the locomotive wheels), allows for a description of the effect of the changing track support condition. Moreover, it also proves its usefulness for the analysis of the changes in deflection and stress values and the force transferred from the rail on the railway sleeper and for the assumed shape of defects simulating the short irregularities arising in the operated railway track. The arising irregularity in the track affects driving comfort and the safety of travellers.

scholarly journals Deformation Law and Control Limit of CRTSIII Slab Track under Subgrade Frost Heave

2021 ◽  
Vol 11 (8) ◽  
pp. 3520
Author(s):  
Xiaopei Cai ◽  
Qian Zhang ◽  
Yanrong Zhang ◽  
Qihao Wang ◽  
Bicheng Luo ◽  
...  
Keyword(s):  
High Speed ◽  
Base Plate ◽  
Element Model ◽  
Middle Part ◽  
Railway Track ◽  
Frost Heave ◽  
Track Structure ◽  
Slab Track ◽  
Plastic Damage ◽  
Track Irregularity

In order to find out the influence of subgrade frost heave on the deformation of track structure and track irregularity of high-speed railways, a nonlinear damage finite element model for China Railway Track System III (CRTSIII) slab track subgrade was established based on the constitutive theory of concrete plastic damage. The analysis of track structure deformation under different subgrade frost heave conditions was focused on, and amplitude the limit of subgrade frost heave was put forward according to the characteristics of interlayer seams. This work is expected to provide guidance for design and construction. Subgrade frost heave was found to cause cosine-type irregularities of rails and the interlayer seams in the track structure, and the displacement in lower foundation mapping to rail surfaces increased. When frost heave occured in the middle part of the track slab, it caused the greatest amount of track irregularity, resulting in a longer and higher seam. Along with the increase in frost heave amplitude, the length of the seam increased linearly whilst its height increased nonlinearly. When the frost heave amplitude reached 35 mm, cracks appeared along the transverse direction of the upper concrete surface on the base plate due to plastic damage; consequently, the base plate started to bend, which reduced interlayer seams. Based on the critical value of track structures’ interlayer seams under different frost heave conditions, four control limits of subgrade frost heave at different levels of frost heave amplitude/wavelength were obtained.

scholarly journals Biaxial Shear Load Capacity of Anchor System for Quick-Hardening Track on Railway Bridges

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Kyoung Chan Lee ◽  
Il-Wha Lee ◽  
Seong-Cheol Lee
Keyword(s):  
High Speed ◽  
Ride Comfort ◽  
Load Capacity ◽  
Frictional Resistance ◽  
Shear Capacity ◽  
Railway Track ◽  
Railway Bridges ◽  
Anchor System ◽  
Ballast Track ◽  
Anchor Systems

Quick-hardening railway track was developed to rapidly convert old-style ballast track to slab track in order to improve its maintainability and ride comfort. On bridges, quick-hardening track is applied in a segmented structure to reduce the temperature constraint, and anchors at the centers of the segments securely couple the track to the bridge. In this study, an anchor system is proposed that facilitates fast construction, and two designs for the proposed anchor systems are provided along with experimental test results of the same. Two anchor system designs were developed to allow for the maximum possible longitudinal and transverse loads in high-speed railways while considering the frictional resistance between the track slab and bridge deck. The biaxial shear capacity of each design was investigated experimentally, and the structural capacity for biaxial shear loads was evaluated using an elliptical curve to represent the longitudinal and transverse shear capacities. The minimum friction coefficient was determined based on the results of the evaluation to minimize damage to the anchor. The results obtained from the experiments confirmed that the proposed anchor systems possess sufficient shear capacity for application on high-speed railway bridges.

scholarly journals Characteristics of defect states in periodic railway track structure

2021 ◽  
pp. 146134842110382
Author(s):  
Qiang Yi ◽  
Caiyou Zhao ◽  
Ping Wang
Keyword(s):  
Transmission Coefficient ◽  
Peak Frequency ◽  
Railway Track ◽  
Track Structure ◽  
Defect State ◽  
Defect States ◽  
Transform Method ◽  
Vibration Transmission ◽  
Local Resonance ◽  
Resonance Modes

To overcome the ill-conditioned matrix problem of the traditional transfer matrix method, the Floquet transform method and supercell technology are used to study the defect states of the periodic track structure. By solving the equations of the supercell directly, the propagation characteristics of elastic waves in the track structure with defects are analyzed. The existence of defects destroys the periodicity of track structure, thus resulting in the formation of defect states within the band gaps. Moreover, the elastic wave is localized near the defect position at the frequency of the defect state. The formation mechanism of the defect state in track structure can be explained by the local resonance at the defect. With the expansion of the defect range, the number of local resonance modes that can be formed near the defect increases, thus generating multiple defect states. Furthermore, the defect state enhances the vibration of the structure adjacent to the defect. Therefore, the vibration transmission coefficient in a finite-length range can be used to detect the defect characteristics in the track structure, and the defect degree can be evaluated by the peak frequency of the vibration transmission coefficient within the band gap.

Reducing of negative heavy axle load impact on the railway track structure

2021 ◽  
Author(s):  
Alexey Kolos ◽  
Andrei Petriaev ◽  
Irina Kolos ◽  
Anastasia Konon
Keyword(s):  
Railway Track ◽  
Track Structure ◽  
Load Impact

scholarly journals Analysis of static forces generated in-track on a railway sleeper resting on an elastic foundation due to structural imperfections using the PONTOS system

2019 ◽  
Vol 262 ◽  
pp. 11001
Author(s):  
Włodzimierz Andrzej Bednarek
Keyword(s):  
Theoretical Calculations ◽  
Railway Track ◽  
Bernoulli Beam ◽  
Main Concept ◽  
Field Investigations ◽  
Railway Sleeper ◽  
Foundation Parameters ◽  
Euler Bernoulli Beam ◽  
Structural Imperfections ◽  
Two Parameter

In the paper a considered railway sleeper was analysed as an Euler-Bernoulli beam and a Timoshenko beam of finite length resting on a oneand two-parameter foundation. The foundation parameters were determined based on a modified and analogue Vlasov soil model and field investigations. The main concept for the executed investigations was to induce an intentional imperfection in an actual railway track, propose a way of appropriate measurement (e.g. the PONTOS system by GOM mbh), and utilize author’s field investigations results to calibrate necessary parameters for theoretical calculations. An experimental formula describing the value of the force transferred from the rail to the railway sleeper on the grounds of the survey site caused by a locomotive was given. Furthermore, the deflection of the chosen railway sleeper due to the generated imperfection was analysed. Finally the objective of the present analysis was to resolve the calculations into the beam element such that the results can be utilised in computational railway practice. In the presented paper also the computational examples, diagrams and tables reflecting influence of analyzed parameters on obtained a CWR track’s displacements are enclosed.

scholarly journals Train Speed Estimation from Track Structure Vibration Measurements

2020 ◽  
Vol 10 (14) ◽  
pp. 4742
Author(s):  
Xinyue Wang ◽  
Xianfeng Shi ◽  
Jialiang Wang ◽  
Xun Yu ◽  
Baoguo Han
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Geometrical Parameters ◽  
Track Structure ◽  
Speed Estimation ◽  
Vibration Measurements ◽  
Structural Health ◽  
Treatment Techniques ◽  
Train Speed ◽  
Structure Vibration

This paper proposes a new method for train speed estimation from track structure vibration measurements for field track structural health monitoring. This method employed image treatment techniques, wavelet transform, and short-time Fourier transform into the signal processing. Afterward, the train speed was estimated by the combination of the extracted features and the geometrical parameters of the passing trains. A total of 240 measurements, gotten from 20 trains measured by 12 sensors, were implemented to verify the effectiveness and practicability of the proposed method. The results showed that the average differences of the train speed calculating by phase differences and the proposed method were 0.61% for slab displacement measurements, 1.39% for rail acceleration measurements, and 2.97% for slab acceleration measurements, respectively. Furthermore, the proposed method was proved to be effective in different test locations and track structure state. Therefore, it is concluded that the proposed method can estimate train speed from the vibration measurements automatically, reliably, and in real time with no need for additional speed measurement modules, which meets the requirement of speed estimation in the short-term, multi-location, and tough environment of structural health monitoring.

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