Experimental monitoring and numerical modeling of thermal regime of railway track structure - preliminary results and conclusions

2017 ◽  
Vol 44 (4) ◽  
pp. xxx-xxx
Keyword(s):  
Numerical Modeling ◽  
Thermal Regime ◽  
Railway Track ◽  
Track Structure ◽  
Preliminary Results

scholarly journals NUMERICAL MODELLING OF THERMAL REGIME OF RAILWAY TRACK - STRUCTURE WITH THERMAL INSULATION (STYRODUR)

2021 ◽  
Vol 27 (7) ◽  
pp. 525-538
Author(s):  
Libor Ižvolt ◽  
Peter Dobeš ◽  
Michaela Holešová ◽  
Deividas Navikas
Keyword(s):  
Numerical Modelling ◽  
Thermal Insulation ◽  
Thermal Regime ◽  
Climatic Factors ◽  
Railway Track ◽  
Track Structure ◽  
Insulation Layer ◽  
Surface Level ◽  
Main Factors ◽  
Climatic Characteristics

This paper presents the results of numerical modelling of the influence of various factors (geometrical layout of the structural layers of the railway track, climatic factors and ballast fouling) on the freezing of railway track structure with a built-in thermal insulation layer of extruded polystyrene (Styrodur). At the same time, the suitability and expediency of incorporating the thermal insulation layer at the sub-ballast upper surface level (i.e. below the rail ballast construction layer), or at the level of subgrade surface are discussed. Numerical modelling results in the main factors that should be taken into account in the dimensioning of the sub-ballast layers with a built-in thermal insulation layer. Based on the data on the depth of freezing of the railway track structure obtained from numerical modelling, a design nomogram for dimensioning was created and subsequently the influence of the changes of climatic characteristics on the freezing of the railway track structure was then mathematically expressed.

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 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.

Sign in / Sign up

Export Citation Format

Share Document