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 Modelling of Railway Track Temperature Regime with Real Heat-Technical Values for Different Climatic Characteristics

2017 ◽  
Vol 13 (2) ◽  
pp. 134-142 ◽  
Author(s):  
Stanislav Hodás ◽  
Alžbeta Pultznerová
Keyword(s):  
Numerical Modelling ◽  
Temperature Regime ◽  
Railway Track ◽  
High Quality ◽  
Time Operation ◽  
Negative Temperatures ◽  
Freezing Period ◽  
Long Time ◽  
Climatic Characteristics

Abstract High quality of railway track construction is a major priority. One of the quality elements is the resistance to load of railway formation with individual structural layers caused by negative temperatures during the critical freezing period of winter. Numerical modelling allows obtaining more control outputs at different climatic loads. The presented paper shows the load of railway track model with different variants of climate and shows the importance in the designing of the non-transport load under negative temperatures, i.e. observation of transition of the zero isotherm through the layers of railway subgrade. If the subgrade layers of the railway formation are built with high quality and durability then the axis of the track will keep its geometric spatial position during the long-time operation.

scholarly journals Transverse Cracking of Concrete Base Plate in CRTS III Ballastless Track Structure: Effects of Environmental Boundary Conditions

2021 ◽  
Vol 11 (21) ◽  
pp. 10400
Author(s):  
Weiqiang Guo ◽  
Xin Huang ◽  
Lijun Zhao ◽  
Ya Wei
Keyword(s):  
Numerical Modelling ◽  
Boundary Conditions ◽  
Base Plate ◽  
Test Series ◽  
Railway Track ◽  
Early Age ◽  
Track Structure ◽  
Transverse Cracking ◽  
Ballastless Track ◽  
Concrete Base

The cast-in-place concrete base plate is a main member of the China Railway Track System (CRTS) III ballastless track structure that is prone to generating early transverse cracking. Such cracks can dramatically affect the performance and service life of the railway track structure. This study investigated the influence of temperature and moisture boundary conditions on early cracking behavior of the CRTS III base plate by using approaches of both in situ measurements and numerical modelling. In-site measurements of strain and temperature were made in four test series of CRTS III base plates under the same natural environmental condition but cured with different regimes, and a total of 96 measuring positions were monitored for up to 150 days. The results showed that the strain magnitude and distribution in the field base plate, the initial time at cracking, and the observed cracking pattern varied significantly between the different test series. In order to understand the mechanisms that create these transverse cracks and to provide guidelines for the current curing strategy during construction, the characteristics of temperature-induced and moisture-induced stresses were analyzed by using 3D numerical modelling and by considering early-age concrete creep properties, meteorological factors, and the influence from environmental boundary conditions. The calculated results revealed that early-age transverse cracking in CRTS III base plate depends more on drying shrinkage stress than temperature stress. By conducting this study, we expect to provide guidance for reducing or eliminating early cracks of CRTS III concrete base plate.

microplastics, numerical modelling, the Baltic Sea, anthropogenic pollution

2017 ◽  
Author(s):  
Andrei Bagaev ◽  
Andrei Bagaev ◽  
Irina Chubarenko ◽  
Irina Chubarenko
Keyword(s):  
Numerical Modelling ◽  
Baltic Sea ◽  
Anthropogenic Pollution ◽  
Anthropogenic Pressure ◽  
Marine Waters ◽  
The Baltic Sea ◽  
Main Factors ◽  
The Baltic ◽  
Semi Empirical ◽  
The Given

An overview of modern approaches to the problem of parametrisation of sources of marine waters microplastics pollution from the coastline is conducted. The estimates of Europe’s plastic production along with mismanaged plastic waste percentage that might be the source of microplastics particles input to marine environment are presented. A semi-empirical for-mulation for the particles source intensity is suggested. It considers the main factors of local anthropogenic pressure for the coastal spot location for the given coordinates. Both ad-vantages and disadvantages of such an approach along with possible ways for improvement are discussed.

microplastics, numerical modelling, the Baltic Sea, anthropogenic pollution

2017 ◽  
Author(s):  
Andrei Bagaev ◽  
Andrei Bagaev ◽  
Irina Chubarenko ◽  
Irina Chubarenko
Keyword(s):  
Numerical Modelling ◽  
Baltic Sea ◽  
Anthropogenic Pollution ◽  
Anthropogenic Pressure ◽  
Marine Waters ◽  
The Baltic Sea ◽  
Main Factors ◽  
The Baltic ◽  
Semi Empirical ◽  
The Given

An overview of modern approaches to the problem of parametrisation of sources of marine waters microplastics pollution from the coastline is conducted. The estimates of Europe’s plastic production along with mismanaged plastic waste percentage that might be the source of microplastics particles input to marine environment are presented. A semi-empirical for-mulation for the particles source intensity is suggested. It considers the main factors of local anthropogenic pressure for the coastal spot location for the given coordinates. Both ad-vantages and disadvantages of such an approach along with possible ways for improvement are discussed.

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.

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