• Volume 38,Issue 4,2021 Table of Contents
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    • >交通基础设施
    • Research Progress in the Long-Term Settlement of Soft Soil Subgrade Subjected to Train Load

      2021, 38(4):1-7. DOI: 10.16749/j.cnki.jecjtu.2021.04.002 CSTR:

      Abstract (360) HTML (0) PDF 1.82 M (2846) Comment (0) Favorites

      Abstract:Recently, with the rapid development of the high-speed railway in our country, the long-term settlement of the soft soil subgrade subjected to train load has attracted our attention. In this work, the application of constitutive model method, experiment model and the machine learning method on the calculation and prediction of the settlement of subgrade was reviewed briefly. The investigation shows that the unified recognition to the train load was not formed. The influence of modulus softening of the subgrade subjected to the train load on the longterm settlement of subgrade are not considered, and the influence of the load harmonic was also not considered.

    • Damage Diagnosis of Space Grid Structure Based on Natural Frequency Clustering Analysis under Varying Temperature Effects

      2021, 38(4):8-17. DOI: 10.16749/j.cnki.jecjtu.2021.04.003 CSTR:

      Abstract (421) HTML (0) PDF 2.38 M (2009) Comment (0) Favorites

      Abstract:Natural frequency is one of the main dynamic characteristics of damage diagnosis methods, which is not only related to the stiffness change of the structure itself, but also easily affected by environmental factors such as temperature. A natural frequency clustering analysis method is proposed, which is used for damage diagnosis of space grid structure under environmental changes. First, the influence of the natural frequency of the structure on the environmental temperature is derived. based on this analysis, a grid is used as the research object to simulate the natural frequency data under the condition of temperature changes and damage; then the principal component analysis (PCA) of the natural frequency is developed, and the structural damage diagnosis was realized by using fuzzy c-mean(FCM) clustering based on principal component reconstruction residuals. The research results show that the ambient temperature affects the natural frequency by causing thermal deformation,changing the material properties and generating temperature internal forces; the daily fluctuation of the naturalfrequency with temperature will directly affect the accuracy of damage diagnosis, and the PCA-FCM clustering can be used in the damage diagnosis process which can effectively eliminate the interference of environmental temperature factors, judge whether the damage occurs when the health baseline is unknown, and accurately judge the degree of damage.

    • Analysis of Vibration Characteristics of Elevated Box Girder Structure Induced by High-Speed Train at 300 km/h

      2021, 38(4):18-26. DOI: 10.16749/j.cnki.jecjtu.2021.04.004 CSTR:

      Abstract (246) HTML (0) PDF 2.27 M (1636) Comment (0) Favorites

      Abstract:In order to reveal the mechanism of vibration generation and transmission of high -speed railway bridge structure, the vibration characteristics of elevated box girder structure induced by 300 km/h high-speed train were studied by numerical method and field measurement respectively. Firstly, a three-dimensional finite element dynamic model of the simply supported elevated box girder is established to analyze the vibration char acteristics and transmission law of the elevated box girder structure when the train passes at a speed of 300 km/h. Then, an elevated track in Gaoan-Nanchang section of Shanghai-Kunming high-speed railway was selected to conduct field tests on the vibration of the bridge structure caused by high-speed trains, and the finite element calculation results were compared with the measured results. The results show that the finite element analysis is in good agreement with the field measurement results in the range of 20 Hz to 400 Hz. The dominant frequency of bridge structure vibration is 31.5~125 Hz, the peak frequency is 31.5~63 Hz, and there is an obvious trough at 16 Hz. When the frequency is greater than 200 Hz, the vibration level of the acceleration of the bridge struc-ture drops sharply. Therefore, the vibration reduction design of the bridge structure can be carried out accordingto the frequency of 31.5~63 Hz. The vibration level of the maximum acceleration of the bridge roof is 88.59~ 100.48 dB, and the corresponding peak frequency is 31.5 Hz and 40 Hz. The maximum acceleration vibration level of the bridge floor is 82.96~94.29 dB, and the corresponding peak frequency is 31.5 Hz and 63 Hz. The vibration of the box girder floor contributes the most to the vibration of the bridge structure.

    • Advance in Research on Applications of Digital Twin in Intelligent Railway Operation Management

      2021, 38(4):27-44. DOI: 10.16749/j.cnki.jecjtu.2021.04.005 CSTR:

      Abstract (964) HTML (0) PDF 2.03 M (5132) Comment (0) Favorites

      Abstract:China’s railway infrastructure construction is developing from “construction-oriented” to “construction and management balanced.” Traditional operation and maintenance methods have many drawbacks, and there is an urgent need to establish an innovative intelligent operation and maintenance system. Digital Twin (DT), a technology of interacting between the real physical system and virtual counterpart, overcomes the limitations of traditional simulations and test conditions, and can offer the accurate assessment for actual operating condition at the fastest speed and optimal cost. digital twin can interact with Internet of Things, Building Information Modelling, Structural Health Monitoring, numerical simulation and artificial intelligence through the integration of real physical system and the associated virtual model in order to realize the real-time monitoring, simulation, prediction, diagnosis and decision-making of the system. This paper reviews critically the research progress, basic principles and technical methods of digital twin, and discusses the applications of Digital Twin integrating with Building Information Modelling, structural health monitoring, artificial intelligence, New Information Technology, etc. Then, the research advances of the applications of digital twin in railway operation and maintenance are summarized, including intelligent inspection (monitoring) testing, digital twin virtual modeling, performance degradation modeling, and optimized maintenance strategy determination. Finally, this paper presents the framework for intelligent operation and maintenance of railway infrastructure by using digital twin technology,and discusses the main problems and solutions of its applications in railway maintenance. From the critical review, the digital twin technology can provide a methodology for intelligent railway operation and maintenance management.

    • Study on Dynamic Displacement of Ballastless Track Subgrade Under High-Speed Moving Load

      2021, 38(4):45-53. DOI: 10.16749/j.cnki.jecjtu.2021.04.006 CSTR:

      Abstract (253) HTML (0) PDF 2.26 M (1959) Comment (0) Favorites

      Abstract:A nonlinear numerical analysis model for three -dimensional finite element of CRTS Ⅲ slab ballast less track -subgrade -natural foundation soil is established, and the wheel/rail load is calculated based on the random irregularity of the track. The wheel/rail load is imported into the finite element model by secondary development subroutine of finite element software, and the equivalent three-dimensional uniform viscoelastic artificial boundary is used to simulate the actual semi-infinite space at both ends of the subgrade around the natural foundation soil. Accordingly, the dynamic displacement distribution of subgrade under high speed moving load is studied and analyzed. The results show that the vertical dynamic displacement of the subgrade calculated by the finite element model is far less than the current standard control value of China’s high-speed railway of 3.5 mm,which meets the requirements. The train model adopts two bullet cars, and the dynamic displacement generatedby the movement of two sets of wheel sets in the middle is superimposed. The peak value of the vertical dynamic displacement in the time history curve of each structure layer corresponds to the number of bogies. In the range of concrete base, the vertical dynamic displacement amplitude of each structural layer of subgrade changes little along the transverse distribution, and the maximum transverse difference of each structural layer is only 0.129 mm. Outside the range of concrete base, the vertical dynamic displacement amplitude of each structural layer of subgrade has a great difference in transverse distribution, and the maximum transverse difference is more than 0.5 mm. With the increase of depth, the vertical dynamic displacement in the subgrade gradually attenuates, and the maximum value is located at the top surface of the foundation bed, which attenuates approximately linearly. The impact of roadbed surface stiffness changes on the system dynamic response is limited. The increase of the roadbed foundation stiffness has a significant effect on reducing the dynamic displacement of the subgrade, which is conducive to the smooth, comfortable and safe running of the train. The increase of the train speed increases the deformation displacement of the subgrade. The change of the foundation soil stiffness has the most significant effect on reducing the dynamic displacement of the system in the subgrade.

    • Review on Railway Vibration and Noise Reduction Based on Phononic Crystal Theory

      2021, 38(4):54-63. DOI: 10.16749/j.cnki.jecjtu.2021.04.007 CSTR:

      Abstract (448) HTML (0) PDF 1.77 M (2255) Comment (0) Favorites

      Abstract:To further study the issue of railway vibration and noise in the railway operation and maintenance,the elastic wave propagation characteristics of the multiple equal pan rail,bridge,and tunnel,as well as vibration and noise reduction control of noise barriers and periodic vibration isolation,have been researched by domestic and foreign scholars based on phononic crystal theory. By introducing the band gap control mechanism of phononic crystal and summarizing the research theory on vibration and noise reduction in the periodic track, bridges and tunnels based on phononic crystal in recent years,this paper reviews the vibration control methods of periodic structure,phononic crystal noise barrier and vibration isolation. The future theoretical research suggestions and prospects are finally presented.

    • >交通管理与控制
    • Adaptive Braking Control for High-Speed Trains with Disturbances and Time Delays

      2021, 38(4):64-71. DOI: 10.16749/j.cnki.jecjtu.2021.04.008 CSTR:

      Abstract (571) HTML (0) PDF 2.05 M (2267) Comment (0) Favorites

      Abstract:To ensure the safe and reliable operation of high -speed trains, this paper develops a new adaptive control scheme for the braking system of high-speed trains with unknown disturbances and input time delays, which realizes the asymptotic tracking of given speed curve. By analyzing the principle and dynamic characteristics of braking systems, a state space model of high-speed trains with disturbances and input time delays is established. A state feedback control law is designed based on state prediction and the capacity of model reference adaptive control to deal with system uncertainties and disturbances, thus realzing the asymptotic tracking of given speed curve in presence of unknown disturbances and input time delays. The data in Jinan-Qingdao section of CRH380AL type of high-speed trains are used for simulation study. Simulation results show the desired stability, tracking performance, and robustness in dealing with unknown parameters and bounded disturbance.

    • Detection and Recognition of Bird Nests in Overhead Catenary Systems Based on Improved YOLOv3

      2021, 38(4):72-80. DOI: 10.16749/j.cnki.jecjtu.2021.04.009 CSTR:

      Abstract (601) HTML (0) PDF 2.26 M (1847) Comment (0) Favorites

      Abstract:Access to the bird nest is a serious threat to the safe and stable operation of overhead catenary system. An improved YOLOv3 algorithm was proposed to detect and identify the adverse effects of bird nests on railway operation. Firstly, the bird nest image of overhead catenary system is preprocessed in the early stage. The denoising and other operations can enhance the extraction of the essential features of the bird nest, and the data enhancement can avoid the over-fitting phenomenon of the neural network to a certain extent. The spatial pyramid pooling module is added into the network structure, and the feature map is pooled at different scales and then stitched together to get the output of fixed size, and the multi-scale features of the nest are extracted. Finally, the GIoU, which measures the distance between the prediction box and the real box, is used as the bounding box loss function, and the model optimizes the loss and the overlap degree between the real box and the prediction box. The experimental results show that the average accuracy of this method in the overhead contact netnest detection reaches 95.1%, which has a high detection accuracy in the overhead contact net nest detection field, and can better identify and detect the nest under the complex overhead contact net background.

    • >载运工具装备
    • Review of the Novel Super Singular Element Method for Singular Elastic Field Analysis

      2021, 38(4):81-98. DOI: 10.16749/j.cnki.jecjtu.2021.04.010 CSTR:

      Abstract (297) HTML (0) PDF 3.35 M (1480) Comment (0) Favorites

      Abstract:With the development of high quality and high efficiency of urban rail transit, the fatigue strength of engineering and mechanical equipment has attracted more and more attention. The failure of mechanical structures arises from various forms of defects, such as cracks, inclusions, holes, etc. The singularity stress is an important cause of crack initiation at material defects. The novel super singular element is based on numerical eigen-solutions of singular displacement and stress fields and the Hellinger-Reissner variational principle. It is a special element that contains the corner of a defect and can analyze the singular elastic field. Compared with other singular elements, it is versatile and has nothing to do with the size of the element. It can be connected with conventional elements without any transition elements. It can be applied to singular stress field analysis of any interface corner and any material combination. The article mainly reviews the application of the novel supe singular elements in the crack tip, inclusion corner tip, notch corner tip, hole corner tip and multiphase materialsinterface in 2D or 3D, which has a certain guiding significance on how to use this element to analyze singular stress field.

    • Research on Real-Time Monitoring Methods for Railroad Wheel Tread Defects: A Review

      2021, 38(4):99-112. DOI: 10.16749/j.cnki.jecjtu.2021.04.011 CSTR:

      Abstract (515) HTML (0) PDF 2.56 M (4438) Comment (0) Favorites

      Abstract:A brief introduction to the current status of research, characteristics and applications of real -time monitoring methods for train wheel tread damage is presented. The train wheel tread defects detection method has two kinds of in-workshop inspection and in-service inspection. Among them, the in-service inspection of good real-time, can provide the technical basis for the realization of real-time monitoring of wheel tread defect. According to the different sensor installation locations,the in-service inspection can be divided into two types of on -board measurement and wayside measurement. The methods of wayside measurement, such as wheel -rail force detection, image detection and acoustic emission detection, as well as axle box vibration and acceleration detection and fiber optic sensing detection are introduced, summarized, and analyzed in terms of their principles, research status and application problems. The results show that the existing monitoring methods still need further improvement, and in future research it is necessary to consider the integration of real-time wheel defect monitoring methods with intelligent diagnosis, big data and Internet of Things technologies, with the function of fault warning and equipment remaining life prediction, to realize the application of intelligent operation and maintenance technology in high-speed railroad construction.

    • Research Status of Current-Carrying Friction and Wear in Pantograph-Catenary System

      2021, 38(4):113-125. DOI: 10.16749/j.cnki.jecjtu.2021.04.012 CSTR:

      Abstract (514) HTML (0) PDF 2.44 M (2265) Comment (0) Favorites

      Abstract:With the development of power transmission system, modern railway transportation system, industrial generators and other fields, the current-carrying friction behavior of pantograph/catenary system (hereinafter referred to as pantograph/catenary system) has attracted much attention. The pantograph-catenary system is the key current receiving part of the electric locomotive. The pantograph needs to obtain electric energy from the catenary when working. Its stability and current receiving quality are related to the reliable and good operation of the electric locomotive. This paper introduces the basic characteristics of current-carrying friction and its evaluation and analysis methods, and expounds four main factors in pantograph-catenary system, namely, tribological parameters, current -carrying parameters, environmental conditions and friction pair materials. The main wear mechanism and the influence of arc ablation in the current-carrying friction process of pantograph-catenary system are mainly discussed. Finally, the full text is summarized and the future research direction is proposed.

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