scholarly journals Numerical analysis on the time-varying temperature field distribution patterns of ballastless track steel-concrete composite box girders at ambient temperature based on field measurements

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Wangqing Wen ◽  
Shiwei Li ◽  
Aiguo Yan ◽  
Jiahua Zeng
Keyword(s):  
Temperature Field ◽  
Wind Speed ◽  
Ambient Temperature ◽  
High Speed ◽  
Time Varying ◽  
Temperature Field Distribution ◽  
Box Girders ◽  
High Speed Railway ◽  
Ballastless Track ◽  
Main Girder

AbstractTo analyze the time-varying temperature field distribution pattern of ballastless track steel-concrete composite box girders for a high-speed railway at ambient temperature, a numerical model for analyzing the time-varying temperature field of steel-concrete composite box girders was established based on the long-term monitoring data for the internal and external environments of the main girder of the Ganjiang Bridge on the Nanchang-Ganzhou high-speed railway. The influence of factors such as the deck pavement and the ambient wind speed on the time-varying temperature field of the steel-concrete composite box girders were considered. The results showed that there was a significant difference in the vertical temperature gradient patterns on sections at the side web and at the middle web at the same moment in time due to the hindering effect of the track board on the heat exchange between the ambient temperature and the main girder. Increasing the wind speed accelerated the rate of heat exchange between the main girder surface and the environment. In particular, when the internal temperature of the girder was higher than the ambient temperature, the higher the wind speed was, the larger the temperature gradient was. This study lays a foundation for accurate analysis of the structural response of ballastless track steel-concrete composite girder bridges at ambient temperature.

Temperature Field Analysis on CA Mortar Ballastless Track of High-Speed Railway

2012 ◽  
Vol 531-532 ◽  
pp. 163-167
Author(s):  
Jun Fu ◽  
Yu Qin ◽  
You Yun Yu ◽  
Meng Jun Ye ◽  
Lian Xin Li
Keyword(s):  
Temperature Field ◽  
High Speed ◽  
Theoretical Data ◽  
Element Model ◽  
Field Analysis ◽  
Systematic Research ◽  
High Speed Railway ◽  
Ballastless Track ◽  
Cushion Layer ◽  
Ca Mortar

As an important cushion layer, CA mortar ballastless track is crucial to the durability, safety of high-speed railway and the high-speed railway is influenced by the external environment. The regulation of temperature field evolvement of ballastless track is analyzed in this paper through a two-dimensional, transient finite element model built by ANSYS. The results show that the temperature of structure section caused by solar radiation and circumstances temperature is decreasing along depth in sunlight, and the internal temperature of structure is higher than the surface temperature at night. The integral temperature field of structure reaches the maximum at 1:00 p.m. and the vertical difference of the temperature inside the structure is also the largest, causing the most obvious temperature stress, which provides theoretical data for systematic research on ballastless track of high-speed railway.

scholarly journals Simulation Study on Vertical Deformation of CRTS III Slab Track under Ambient Temperature and Its Upgrade to “Green Maintenance”

2021 ◽  
Vol 11 (17) ◽  
pp. 7830
Author(s):  
Junzhao Zhou ◽  
Yanyun Luo ◽  
Guosheng Lv ◽  
Yongliang Xiong
Keyword(s):  
Temperature Field ◽  
Temperature Gradient ◽  
Ambient Temperature ◽  
High Speed ◽  
Climatic Conditions ◽  
Vertical Deformation ◽  
Technical Data ◽  
Slab Track ◽  
Ballastless Track ◽  
Elliptical Region

In view of the vertical deformation of CRTS III slab ballastless track of high-speed railways under the action of ambient temperature, a simulation model of the temperature field and vertical deformation of CRTS III slab ballastless track was developed and verified by a field test. The main conclusions are as follows: When the temperature gradient is positive, the central part of the slab track deforms upward. The edge of the slab track deforms downward. The displacement in the central part of the slab track is the largest, and the elliptical region is formed in the middle. The more outward the displacement is, the smaller the displacement is. When the temperature gradient is negative, the downward displacement in the middle of the slab track is the largest, an elliptical region is formed in the middle, and the outward displacement gradually changes from downward to upward. The model developed in this study can accurately reflect the temperature field inside the slab track and the vertical displacement of the slab track at the macro level. In practical application, the technical data can be provided for the maintenance of CRTS III slab tracks according to the simulation results. The temperature field distribution and possible deformation of the slab track can be obtained by adding simulated working conditions according to the climatic conditions. These predictions can be used to focus on targeted maintenance and repair to reduce the investment of human, material, and financial resources, and to achieve the purpose of “green maintenance”.

scholarly journals Mechanical Performance of a Ballastless Track System for the Railway Bridges of High-Speed Lines: Experimental and Numerical Study under Thermal Loading

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2876
Author(s):  
Yingying Zhang ◽  
Lingyu Zhou ◽  
Akim D. Mahunon ◽  
Guangchao Zhang ◽  
Xiusheng Peng ◽  
...  
Keyword(s):  
High Speed ◽  
Thermal Loading ◽  
Mechanical Performance ◽  
Track Structure ◽  
Box Girder ◽  
High Speed Railway ◽  
Ballastless Track ◽  
Track System ◽  
Girder Bridge ◽  
Track Slab

The mechanical performance of China Railway Track System type II (CRTS II) ballastless track suitable for High-Speed Railway (HSR) bridges is investigated in this project by testing a one-quarter-scaled three-span specimen under thermal loading. Stress analysis was performed both experimentally and numerically, via finite-element modeling in the latter case. The results showed that strains in the track slab, in the cement-emulsified asphalt (CA) mortar and in the track bed, increased nonlinearly with the temperature increase. In the longitudinal direction, the zero-displacement section between the track slab and the track bed was close to the 1/8L section of the beam, while the zero-displacement section between the track slab and the box girder bridge was close to the 3/8L section. The maximum values of the relative vertical displacement between the track bed and the bridge structure occurred in the section at three-quarters of the span. Numerical analysis showed that the lower the temperature, the larger the tensile stresses occurring in the different layers of the track structure, whereas the higher the temperature, the higher the relative displacement between the track system and the box girder bridge. Consequently, quantifying the stresses in the various components of the track structure resulting from sudden temperature drops and evaluating the relative displacements between the rails and the track bed resulting from high-temperature are helpful in the design of ballastless track structures for high-speed railway lines.

scholarly journals Does the Opening of High-Speed Railway Lines Reduce the Carbon Intensity of China’s Resource-Based Cities?

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4648
Author(s):  
Zhipeng Tang ◽  
Ziao Mei ◽  
Jialing Zou
Keyword(s):  
High Speed ◽  
National Average ◽  
Carbon Intensity ◽  
Time Varying ◽  
Low Carbon ◽  
High Speed Railway ◽  
Different Types ◽  
Endogenous Selection ◽  
Mode Of Development ◽  
The Impact

The carbon intensity of China’s resource-based cities (RBCs) is much higher than the national average due to their relatively intensive mode of development. Low carbon transformation of RBCs is an important way to achieve the goal of reaching the carbon emissions peak in 2030. Based on the panel data from 116 RBCs in China from 2003 to 2018, this study takes the opening of high-speed railway (HSR) lines as a quasi-experiment, using a time-varying difference-in-difference (DID) model to empirically evaluate the impact of an HSR line on reducing the carbon intensity of RBCs. The results show that the opening of an HSR line can reduce the carbon intensity of RBCs, and this was still true after considering the possibility of problems with endogenous selection bias and after applying the relevant robustness tests. The opening of an HSR line is found to have a significant reducing effect on the carbon intensity of different types of RBC, and the decline in the carbon intensity of coal-based cities is found to be the greatest. Promoting migration of RBCs with HSR lines is found to be an effective intermediary way of reducing their carbon intensity.

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