scholarly journals Improvement and In-Situ Application of an Evaluation Method of Ballasted-Track Condition Using Digital 2-D Image Analysis

2020 ◽  
Vol 10 (21) ◽  
pp. 7946
Author(s):  
Bongsik Park ◽  
Yeong-Tae Choi ◽  
Hyunmin Kim
Keyword(s):  
Image Analysis ◽  
High Speed ◽  
Evaluation Method ◽  
Recognition Rate ◽  
High Speed Railway ◽  
Analysis Methods ◽  
Track Condition ◽  
Ballasted Track ◽  
Track Irregularity

The advancement in digital image analysis methods has led to the development of various techniques, i.e., quantification of ballast gravel abrasion. In this study, the recognition rate of gravel aggregates has been significantly increased by improving the image analysis methods. The correlation between the track quality index (TQI), which is the standard deviation of vertical track irregularity and represents the condition of a high-speed railway, and the number of maintenance works was analyzed by performing an image analysis on the samples collected from various locations of a high-speed railway. The results revealed that roundness has the highest correlation with the TQI, whereas sphericity has the highest correlation with the number of maintenance works. The ballast replacement would be performed to improve maintenance efficiency if the abrasion of the ballast aggregates becomes approximately 10%.

scholarly journals The Influence of an Integration Time Step on Dynamic Calculation of a Vehicle-Track-Bridge under High-Speed Railway

Mathematics ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 431
Author(s):  
Junjie Ye ◽  
Hao Sun
Keyword(s):  
High Speed ◽  
Coupled Model ◽  
Short Wave ◽  
Integration Time ◽  
Vertical Acceleration ◽  
Dynamic Calculation ◽  
Time Step ◽  
High Speed Railway ◽  
Track Irregularity ◽  
Track Bridge

In order to study the influence of an integration time step on dynamic calculation of a vehicle-track-bridge under high-speed railway, a vehicle-track-bridge (VTB) coupled model is established. The influence of the integration time step on calculation accuracy and calculation stability under different speeds or different track regularity states is studied. The influence of the track irregularity on the integration time step is further analyzed by using the spectral characteristic of sensitive wavelength. According to the results, the disparity among the effect of the integration time step on the calculation accuracy of the VTB coupled model at different speeds is very small. Higher speed requires a smaller integration time step to keep the calculation results stable. The effect of the integration time step on the calculation stability of the maximum vertical acceleration of each component at different speeds is somewhat different, and the mechanism of the effect of the integration time step on the calculation stability of the vehicle-track-bridge coupled system is that corresponding displacement at the integration time step is different. The calculation deviation of the maximum vertical acceleration of the car body, wheel-sets and bridge under the track short wave irregularity state are greatly increased compared with that without track irregularity. The maximum vertical acceleration of wheel-sets, rails, track slabs and the bridge under the track short wave irregularity state all show a significant declining trend. The larger the vibration frequency is, the smaller the range of integration time step is for dynamic calculation.

Stochastic Transverse Earthquake-Induced Damage Track Irregularity Spectrum Considering the Uncertainty of Track-Bridge System

2021 ◽  
pp. 2140004
Author(s):  
Yulin Feng ◽  
Yu Hou ◽  
Lizhong Jiang ◽  
Wangbao Zhou ◽  
Jian Yu ◽  
...  
Keyword(s):  
Simulation Model ◽  
Traffic Safety ◽  
High Speed ◽  
Residual Deformation ◽  
High Speed Railway ◽  
Marquardt Algorithm ◽  
Earthquake Action ◽  
Track Irregularity ◽  
Track Bridge ◽  
Bridge System

The track irregularity spectrum of longitudinally connected ballastless track (LCBT)-bridge systems of high-speed railway was proposed in this paper. First, a simulation model of an LCBT-continuous girder bridge was established by considering the influences of approach bridges and subgrade with track structure. Further, a large number of sample analyses were carried out by taking into account the uncertainty of LCBT-bridge systems and stochastic behaviors of ground motions based on the simulation model. The damage laws of residual deformation of track-bridge system after earthquake actions were studied. Then, an interlayer deformation coordination relationship (IDCR) considering the track irregularity caused by earthquake-induced damage of bearings was developed, and the superposed track irregularity samples were obtained. Finally, by using the improved Blackman–Turkey method and Levenberg–Marquardt algorithm, the LCBT irregularity spectrum, track irregularity spectrogram, track irregularity limit spectrum, and a fitting formula for the track irregularity spectrum on a bridge after the action of earthquakes were obtained. Results obtained from the fitting formula and IDCR were compared, and they indicated that tracks undergone significant high-frequency irregularity diseases after the earthquake action. It was found that the track irregularity spectrum could be roughly divided into three ranges: high-, medium- and low-frequency wavebands. Consequently, this led to an application of a three-segment power function for the fitting of the track irregularity spectrum after the earthquake action. The track irregularity spectrum after the action of earthquakes provides an important theoretical basis for the establishment of seismic design methods for high-speed railway bridges based on the traffic safety performance.

In-situ investigation on mud pumping in ballastless high-speed railway and development of remediation method

2022 ◽  
pp. 100713
Author(s):  
Zhangbo Wan ◽  
Weichang Xu ◽  
Zhiyuan Zhang ◽  
Chuang Zhao ◽  
Xuecheng Bian
Keyword(s):  
High Speed ◽  
High Speed Railway ◽  
In Situ Investigation ◽  
Mud Pumping

Analysis on the track quality evolution law of polyurethane-reinforced ballasted track in high-speed railway

2020 ◽  
pp. 095440972097557
Author(s):  
Jie-Ling Xiao ◽  
Pu Jing ◽  
Si-Xin Yu ◽  
Ping Wang
Keyword(s):  
Standard Deviation ◽  
Test Section ◽  
High Speed ◽  
Ride Comfort ◽  
Normal Operation ◽  
High Speed Railway ◽  
Evolution Law ◽  
Ballasted Track ◽  
One Year ◽  
Track Quality

Polyurethane-reinforced ballasted track (PRBT) can improve the integrity of ballasted track structures and satisfy the high-stability requirements of high-speed railways. In this study, the quality evolution law of PRBT structures after being launched into train service was analyzed, and a reference for structural optimization and maintenance operation was provided. The track geometric state of the PRBT test section of a high-speed railway was measured and monitored for nearly one year after it was launched into operation, and the ballastless track of the adjacent section was selected as a reference. The geometric states of the tracks were evaluated and compared using various parameters, including sliding standard deviation, average standard deviation, and track irregularity spectrum density. Results show that the track quality indexes of the test section, which were in operation for nearly one year, were slightly over the limit. Moreover, the fastener can be finely adjusted for the high-value index sections to further improve the ride comfort. The application effect of PRBT in the subgrade fracture zone was good, which could satisfy the requirements of high-quality transportation as well as the normal operation and maintenance of high-speed railway.

Instability Mechanism of Surrounding Rock for Super-Large Cross Section at High-Speed Railway Tunnel Portal

2013 ◽  
Vol 353-356 ◽  
pp. 1597-1603
Author(s):  
Shuang Lan Wu ◽  
Shi Hao Yang ◽  
Xue Wen Zhang
Keyword(s):  
High Speed ◽  
Surrounding Rock ◽  
Instability Mechanism ◽  
Large Cross Section ◽  
Railway Tunnel ◽  
High Speed Railway ◽  
Construction Procedure ◽  
In Situ Conditions ◽  
Major Factors

Difficulties of tunnel construction mainly appear in the entrance and exit stage, some adverse geological problems may occur. In terms of the tunnel at the Changsha-Kunming section of the Shanghai-Kunming passenger line, firstly, adverse geological phenomena at tunnel exits was described. Secondly, major factors leading to disasters were listed, including geology, hydrology and construction procedure. Combined with in-situ conditions, Finite Element Method (FEM) was used to analyze the instability mechanism of surrounding rock after the upper arch gate was excavated by three-bench seven-step exaction method. At last, through comparison between computed result and measuring data, several basic conclusions was obtained. It can make much sense to similar engineering.

Studies on Surface Preparation Systems for Polyurea Protective Coating of Beijing-Shanghai High Speed Railway Bridge Concrete Beams

2012 ◽  
Vol 455-456 ◽  
pp. 765-774
Author(s):  
Wei Bo Huang ◽  
Xu Dong Liu ◽  
Zhang Jing ◽  
Ping Lu
Keyword(s):  
High Speed ◽  
Concrete Beams ◽  
Surface Preparation ◽  
Concrete Surface ◽  
Free Time ◽  
Railway Bridge ◽  
Surface Adhesion ◽  
High Speed Railway ◽  
Comprehensive Performance

. The comprehensive performance of three kinds of surface preparation systems of polyurea coatings for Beijing-Shanghai High-Speed Railway bridge concrete beams’ protection both in situ and in lab were studied in this paper. The pull-off test and visual inspection were used to determine the adhesion and coverage effect of the bug hole of shot blasted concrete surface. Adhesion tests were conducted both in situ and in lab over a period of 1 year. Five failure models were identified based on the failure mechanisms observed during the tests. It showed that, the adhesion strength of Qtech-112 system increased initially (from 2.7 to 4.8 MPa) and then tended to be stable (about 4.5MPa) both in lab and in situ, E1 and E2 system increased initially (from 1.2 to 1.9 MPa) then decreased to 1.3 MPa under low temperature. The tack free time of Qtech-112 was about 3 hours less than E1 and E2 system. Accordingly, the adhesion and tack-free time of epoxy based system (E1, E2) was very sensitive to application temperature and humidity in jobsite. Polyurethane based system (Qtech-112) have a good adhesion and surface coverage effect to concrete surfaces than epoxy based system under the same ambient condition, it showed an excellent comprehensive performance than epoxy one (E1, E2) both in adhesion and in elimination of pinhole for upcoming polyurea application.

Project of High-Speed Railway and Sustainable Development Evaluating

2011 ◽  
Vol 213 ◽  
pp. 216-220
Author(s):  
Lin Liu ◽  
Wei Liu
Keyword(s):  
Sustainable Development ◽  
High Speed ◽  
Evaluation Method ◽  
Evaluation Framework ◽  
High Speed Railway ◽  
The Sustainable Development ◽  
Advantages And Disadvantages ◽  
Business In China ◽  
Construction Operation ◽  
Evaluating Method

This paper presents an evaluating method to optimize the sustainable development of high-speed railway (HSR). HSR is a quickly expanding business in China and without exception it has both advantages and disadvantages. There are many factors, such as planning, design, construction, operation, consumer utilities, public participation, environmental protection, economic analysis, influencing the sustainable development of HSR. Aiming at the main factors influencing it, a series of indices are picked up and the evaluating method is established which is based on the grey relational analysis (GRA). By using this index, the closest to the best sustainable development state is selected in similarity HSRs. The result shows that the evaluation method based on GRA is simple and scientific and has a potential prospect. The major contribution of this research lies in developing a formal evaluation framework for the sustainable development of HSR and providing useful managerial insights.

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