scholarly journals Mechanical Mechanism Analysis of Warping and Bulging Of Track Slab of High-Speed Railway in Service

2022 ◽  
Vol 2148 (1) ◽  
pp. 012035
Author(s):  
Yali Liu ◽  
Jun Dong ◽  
Guohua Li ◽  
Xi Chen ◽  
Yunkai Zhang
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
High Speed ◽  
Environmental Temperature ◽  
Test Model ◽  
High Speed Rail ◽  
Dynamical Mechanism ◽  
Rail Track ◽  
Ca Mortar ◽  
Track Slab

Abstract Due to warpage and ballooning of high-speed rail track slab caused by debonding and environmental temperature changes during the deterioration of CA mortar layer being extremely concerned in practical engineering, it is based on numerical simulation of typical working conditions and analysis of test model that the deformation dynamics mechanism of track slab of high-speed rail in service is studied in this paper. Firstly, three kinds of damage conditions of CA mortar layer are designed to simulate the partial stress state of track slab under normal, warping and bulging conditions, and the results of model test are compared with those of finite element analysis so that the accuracy and credibility of the numerical simulation method and results are verified. Then, through finite element numerical simulation, the dynamical mechanism of actual full-scale high-speed rail track slab under vibration load is studied. The results show that the warping deformation around the track slab and the bulging deformation in the middle part under the action of positive and negative temperature gradient load caused by environmental temperature change will have a great impact on the structural performance of itself and CA mortar layer; Bulging deformation of track slab is more destructive to its structure than warping deformation. It is of great practical significance to further study the critical position of track plate warpage and bulging deformation, and to optimize and strengthen the structure of this part; The research results are of great significance to further study the deterioration.

scholarly journals Preliminary Study on Assessing Delaminated Cracks in Cement Asphalt Mortar Layer of High-Speed Rail Track Using Traditional and Normalized Impact–Echo Methods

Sensors ◽  
2020 ◽  
Vol 20 (11) ◽  
pp. 3022
Author(s):  
Ying-Tzu Ke ◽  
Chia-Chi Cheng ◽  
Yung-Chiang Lin ◽  
Yi-Qing Ni ◽  
Keng-Tsang Hsu ◽  
...  
Keyword(s):  
High Speed ◽  
Concrete Slab ◽  
Amplitude Spectrum ◽  
Peak Frequency ◽  
High Speed Rail ◽  
Impact Echo ◽  
Rail Track ◽  
Cement Asphalt Mortar ◽  
The Difference ◽  
Ca Mortar

The severe deterioration of a cement asphalt (CA) mortar layer may lead to the movement of the upper concrete slab and impair the safety of the speedy train. In this study, a test specimen simulating the structure of high-speed rail track slabs was embedded with delaminated cracks in various lateral sizes inside the CA mortar layer. Impact–echo tests (IE) were performed above the flawed and flawless locations. In present study, the IE method is chosen to assess defects in the CA mortar layer. Both traditional IE and normalized IE are used for data interpolation. The normalized IE are the simulated transfer function of the original IE response. The peak amplitudes in the normalized amplitude spectrum and the peak frequency in the traditional amplitude spectrum for the top concrete overlay were used to develop simple indicators for identifying the integrity of the CA mortar layer. The index was based on the difference of the experimental peak amplitude and frequency of the ones calculated from previously developed formulas for plates without substrates. As a result, the technique does not require an experimental baseline for the crack assessment. A field test and analysis procedure for evaluating high-speed rail slab systems are proposed.

Influences of CA Mortar Elastic Modulus on Stress and Deformation of Slab Track in High Speed Railway

2011 ◽  
Vol 197-198 ◽  
pp. 1480-1485 ◽  
Author(s):  
Rong Chen ◽  
Wang Ping ◽  
Zhe Liu
Keyword(s):  
Elastic Modulus ◽  
Temperature Gradient ◽  
High Speed ◽  
Plate Theory ◽  
Base Plate ◽  
High Speed Rail ◽  
Slab Track ◽  
The Common ◽  
Ca Mortar ◽  
Track Slab

CA mortar is a key component of slab track. It is used as the material for leveling damping structure layer between the rigid track slab and concrete trackbed of slab track in high speed rail. In order to determine functions of CA mortar with low elastic modulus (EM), the beam/plate theory on elastic foundation was applied to the calculation of slab track’s stress. Under the bonding or no-bonding condition, the influence of CA mortar’s EM on the warping stress and displacement of track slab were calculated. Stress distribution of CA mortar under the common effects of train load and temperature gradient was explored, and the intensity requirement of CA mortar with different EM was put forward. Calculation results show that longitudinal and lateral bending moments of base plate both increase with the increasing of CA mortar’s EM; when the CA mortar’s EM is in the range of 50～10000MPa, there is gap between track slab and the mortar and the deformation of CA mortar (50mm thick) is not enough to compensate the warpage of the track slab; with the increasing of CA mortar’s EM, the tensile and compressive stresses of CA mortar both increase under the common effects of train load and temperature gradient, thus higher requirements on tensile and compressive strength are demanded when CA with high elastic modulus is used.

Research on Performance of CRTS I Cement-Emulsified Asphalt Mortar on Site

2017 ◽  
Vol 1142 ◽  
pp. 334-339
Author(s):  
Heng Qiong Jia ◽  
Tao Wang ◽  
Zhao Wei
Keyword(s):  
High Speed ◽  
Pore Diameter ◽  
Woven Fabrics ◽  
High Speed Railway ◽  
Ballastless Track ◽  
Emulsified Asphalt ◽  
Internal Pore ◽  
Ca Mortar ◽  
Asphalt Mortar ◽  
Track Slab

For construction method of infusion bag, expansion of CRTSⅠCA mortar on site by core drilling, water absorption, chloride ion permeability and frost resistance and other properties were studied in comparison with performance of mortar in laboratory under standard curing. The results showed that expansion of the mortar on site was 2%, water absorption was 0.5%, charge amount was 210C, quality loss after 300 freeze-thaw cycles was -1.1%, the performance was much better than molded mortar in laboratory. Pore structure analysis showed that the internal pore diameter of the mortar on site was about 150μm, pore content was 9% to 12%; the internal pore diameter of the mortar in laboratory was also about 150μm, pore content was 10% to 15%. China railway track system（CRTSⅠ）slab ballastless track is one of the main structure forms of the modern high-speed railway and mainly composed of concrete basement, the Cement-emulsified Asphalt Mortar layer and concrete slab, featured by its rapid construction, convenient maintenance, and so on, has been widely applied in high-speed railway construction in our country. The cement-emulsified asphalt（CA） Mortar is one of the key materials and structures in slab ballastless track, providing the appropriate stiffness and elasticity which is usually composed of cement, emulsified asphalt, grit, water and many types of additives, containing a variety of inorganic/organic compositions and many types of surfactants, through the special bag, filling inside the flat cavity by its own weight between track slab and concrete basement with a thickness of 50mm (length×width 4962 mm×2400 mm). The construction method of CA mortar is grouting the non-woven fabrics bag after setting the bag under the track slab fixed by fine adjustment claw, which is convenient and has no requirement of mould removal. The bag is fixed before the perfusion process and does not produce wrinkles. The method greatly enhances the construction efficiency and has been widely utilized in high-speed railway. To full perfusion and tightness with track board, CA mortar contains gas former and expands after the end of infusion in a restricted state. Non-woven fabrics bag itself with breathable permeable, a small amount of water seeps around infusion bags in a period of time after the end of the infusion. Theoretically free water seepage of mortar on the one hand increases the compactness and durability of the mortar, but on the other hand will reduce the mortar expansion; the quality of filling layer mortar can meet the acceptance requirements in the engineering practice. In the same raw materials and mortar mixing, the performance of fresh mortar can require CRTSⅠ type of slab track emulsified asphalt cement mortar in high-speed railway Q / CR 469-2015. After water seepage performance of hardening mortar on site is different from laboratory mortar, because the surface of laboratory mortar is without compression and free deformation. In this paper, contrast mortar on site and molded mortar in laboratory, the performance of hardened mortar on site were studied.

SHM deformation monitoring for high-speed rail track slabs and Bayesian change point detection for the measurements

2021 ◽  
Vol 300 ◽  
pp. 124337
Author(s):  
Qi-Ang Wang ◽  
Cheng Zhang ◽  
Zhan-Guo Ma ◽  
Jiandong Huang ◽  
Yi-Qing Ni ◽  
...  
Keyword(s):  
Change Point ◽  
High Speed ◽  
Deformation Monitoring ◽  
Change Point Detection ◽  
High Speed Rail ◽  
Rail Track ◽  
Point Detection

The Computational Analysis of Hanging-Weight Method Used in High Speed Rail

2011 ◽  
Vol 291-294 ◽  
pp. 1773-1778
Author(s):  
Hao Yu Wang ◽  
Hong Xiao ◽  
Bo Wen Hou
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Computational Analysis ◽  
Component Part ◽  
High Speed Rail ◽  
Deflection Measurement ◽  
Test Parameters ◽  
Weight Method ◽  
Deflection Test

This paper focuses on the feasibility of the hanging-weight method in bridge deflection test of high speed rail. Firstly, it explains principles and component part. And then it proposes steps to determine test parameters. Lastly, it demonstrates the feasibility and reliability of this method by numerical simulation. The result shows the hanging-weight method satisfies the precision of bridge deflection measurement in high speed rail.

A Method of Acquiring and Processing GIC Signal in High-Speed Rail Track Circuit

2014 ◽  
Vol 1070-1072 ◽  
pp. 755-758
Author(s):  
Yun Feng Ma ◽  
Wei Zong
Keyword(s):  
High Speed ◽  
Signal Acquisition ◽  
High Speed Rail ◽  
High Speed Railway ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Rail Track ◽  
Sampled Signal ◽  
Low Pass ◽  
Track Circuit

The high-speed railway is a typical ground systems, if subjected to a larger GIC, will lead to serious incidents. For the power supply and wiring pattern of high-speed railway is different from the public grid, then how to monitor the GIC impact on the high-speed rail electrical systems need to be studied. The paper study the process and pattem of GIC in high-speed rail track circuit, and propose a signal acquisition method of GIC in the track circuit. The sampled signal will be go through the low-pass filter designed by the window function to obtain the GIC.

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