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 Analysis of Influencing Mechanism of Subgrade Frost Heave on Vehicle-Track Dynamic System

2020 ◽  
Vol 10 (22) ◽  
pp. 8097
Author(s):  
Liang Gao ◽  
Wenqiang Zhao ◽  
Bowen Hou ◽  
Yanglong Zhong
Keyword(s):  
Dynamic System ◽  
High Speed ◽  
Frost Heave ◽  
Leverage Effect ◽  
Cold Regions ◽  
Severe Problem ◽  
Slab Track ◽  
Influencing Mechanism ◽  
Track System ◽  
Track Irregularity

Uneven subgrade frost heave has been a severe problem for the operation of high-speed railways in cold regions. In order to reveal the influencing mechanism of frost heave on the vehicle-track system, a novel FEM (finite element method) model based on an explicit algorithm was proposed. In the novel model, the existence of the leverage effect in slab track, which was caused by frost heave, was realistically reproduced at first, and then the vehicle model started running for evaluating the influence of the frost heave on the whole dynamic system. Results show that the leverage effect plays a key role in analyzing the influence of frost heave on the vehicle-track system, besides for track irregularity and contact loss. Specifically, the leverage effect decreases the stability of the slab track and causes an increase in dynamic irregularity. The roles of the track irregularity and the contact loss in the influencing mechanism were also revealed. With the ratio of wavelength to amplitude increasing, the track irregularity is gradually dominant in the influence mechanism of frost heave on the vehicle-track system. The research could provide a reference for the management and maintenance of the slab track in cold regions.

scholarly journals A Review of Different Aspects of Applying Asphalt and Bituminous Mixes under a Railway Track

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 169
Author(s):  
Kazem Jadidi ◽  
Morteza Esmaeili ◽  
Mehdi Kalantari ◽  
Mehdi Khalili ◽  
Moses Karakouzian
Keyword(s):  
High Speed ◽  
Review Paper ◽  
Railway Track ◽  
High Speed Train ◽  
Slab Track ◽  
Bituminous Mixtures ◽  
Railway Tracks ◽  
Potential Applications ◽  
Heavy Loads ◽  
Design And Construction

Asphalt is a common material that is used extensively for roadways. Furthermore, bituminous mixes have been used in railways, both as asphalt and as mortar. Different agencies and research institutes have investigated and suggested various applications. These studies indicate the benefits of bituminous material under railways, such as improving a substructure’s stiffness and bearing capacity; enhancing its dynamic characteristics and response, especially under high-speed train loads; waterproofing the subgrade; protecting the top layers against fine contamination. These potential applications can improve the overall track structure performance and lead to minimizing settlement under heavy loads. They can also guarantee an appropriate response under high-speed loads, especially in comparison to a rigid slab track. This review paper documents the literature related to the utilization of asphalt and bituminous mixes in railway tracks. This paper presents a critical review of the research in the application of asphalt and bituminous mixes in railway tracks. Additionally, this paper reviews the design and construction recommendations and procedures for asphalt and bituminous mixes in railway tracks as practiced in different countries. This paper also provides case studies of projects where asphalt and bituminous mixes have been utilized in railway tracks. It is anticipated that this review paper will facilitate (1) the exchange of ideas and innovations in the area of the design and construction of railway tracks and (2) the development of unified standards for the design and construction of railway tracks with asphalt and bituminous mixtures.

The Calculation of the Supporting Stress of Track Plate in Ballastless High-Speed Rail Structure

2011 ◽  
Vol 97-98 ◽  
pp. 3-9
Author(s):  
Yang Wang ◽  
Quan Mei Gong ◽  
Mei Fang Li
Keyword(s):  
Stress Distribution ◽  
High Speed ◽  
Design Theory ◽  
Moving Load ◽  
Structure Design ◽  
Track Structure ◽  
Beam Model ◽  
High Speed Rail ◽  
Slab Track ◽  
Ballastless Track

The slab track is a new sort of track structure, which has been widely used in high-speed rail and special line for passenger. However, the ballastless track structure design theory is still not perfect and can not meet the requirements of current high-speed rail and passenger line ballastless track. In this paper, composite beam method is used to calculate the deflection of the track plate and in this way the vertical supporting stress distribution of the track plate can be gotten which set a basis for the follow-up study of the dynamic stress distribution in the subgrade. Slab track plate’s bearing stress under moving load is analyzed through Matlab program. By calculation and analysis, it is found that the deflection of track plate and the rail in the double-point-supported finite beam model refers to the rate of spring coefficient of the fastener and the mortar.The supporting stress of the rail plate is inversely proportional to the supporting stress of the rail. The two boundary conditions of that model ,namely, setting the end of the model in the seams of the track plate or not , have little effect on the results. We can use the supporting stress of the track plates on state 1to get the distribution of the supporting stress in the track plate when bogies pass. Also, when the dynamic load magnification factor is 1.2, the track plate supporting stress of CRST I & CRST II-plate non-ballasted structure is around 40kPa.

scholarly journals Numerical Analysis of Vibration Responses in High-Speed Railways considering Mud Pumping Defect

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Ting Li ◽  
Qian Su ◽  
Kang Shao ◽  
Jie Liu
Keyword(s):  
High Speed ◽  
Coupled Model ◽  
Test Results ◽  
External Excitation ◽  
Slab Track ◽  
Vibration Responses ◽  
Track Irregularity ◽  
Mud Pumping ◽  
Element Theory ◽  
Good Agreement

As a newly appeared defect under slab tracks in high-speed railways, mud pumping weakens the support ability of the subgrade to slab track, bringing about deviations on the vibration responses of the vehicle, slab track, and subgrade. Therefore, this paper proposes a vehicle-slab track-subgrade coupled model based on the multibody simulation principle and the finite element theory to highlight the influences of mud pumping defect. As an external excitation to this model, random track irregularity is considered. In order to simulate the mud pumping defect, the contact between the concrete base and subgrade is described as a spring-damper system. This model is validated by field test results and other simulation results, and a very good agreement is found. The vibration responses of the vehicle, slab track, and subgrade under different mud pumping lengths and train speeds are studied firstly. The deviations of vibration responses in high-speed railways induced by mud pumping are then obtained, and the limited mud pumping length is put forward finally to provide a recommendation for maintenance works of high-speed railways in practice.

Characteristic of Longitudinal Coupled Prefabricated Slab Track (LCPBT): Numerical Simulation Analysis of Uneven Sub Grade Performance

2014 ◽  
Vol 501-504 ◽  
pp. 474-479
Author(s):  
Workuha Dagnew Assefa ◽  
Juan Juan Ren
Keyword(s):  
High Speed ◽  
Simulation Analysis ◽  
Structural Characteristics ◽  
Base Plate ◽  
Slab Track ◽  
Track System ◽  
Low Degree ◽  
Grade Performance ◽  
Ca Mortar ◽  
Consolidation Time

With in the development of high-speed railway countrys China is one of the competent use of ballast less track spreader and largely applied on sub grade, in order to ensure high speed, safe and comfortable run of the train, the sub grade structure must provide smoother and more stable support for the upper track structure, but the problems caused by non uniformity sub grade structure performance are increasingly prominent. There have many serious problems such as low precision of measurement, low degree of automation, compaction mechanism, sometimes consolidation time and high interference of human factors. This paper described as the structural characteristics of longitudinal coupled prefabricated slab track System similar to bögl from German, a model for static analysis has been developed. Based on the model, the slab track element is presented. This element includes rail, rail fastening, prefabricated slab, CA mortar, and base plate and sub grade.

The Minimum Longitudinal Horizontal Linear-Stiffness of Piers of Typical High-Speed Railway’s Layout of Turnout and Bridge

2011 ◽  
Vol 255-260 ◽  
pp. 3979-3983
Author(s):  
Zhe Liu ◽  
Wang Ping
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Element Model ◽  
Comprehensive Analysis ◽  
Track Structure ◽  
Continuous Beam ◽  
High Speed Railway ◽  
Railway Bridges ◽  
Ballast Track ◽  
Typical Layout

The values of longitudinal horizontal linear-stiffness of piers are very important parameters in the design of welded turnout on bridge and they can have a great impact on the force and displacement of the turnout. The layout form of turnout and bridge of welded turnout structure system on high-speed railway bridges are various, so the values of longitudinal horizontal linear-stiffness of piers have to be limited in order to insure the strength and stability of track structure on bridges and at the same time meet the requirement of comparative displacement of beam and rail, turnout proper and frog. To make the value-taking easy in the design process, a finite element model for welded turnout-bridge-platform is established in this paper, which is based on the principle of longitudinal interaction of welded turnout on bridges. Directing at three typical layout forms (No.18 single turnout+4×32m continuous beam, single crossover+6×32m continuous beam and typical throat point+4×32m continuous beam) of welded turnout and bridge on ballast track, a research of the relation between the force and displacement of turnout, and the values of longitudinal horizontal linear-stiffness of piers has been carried out. Based on the comprehensive analysis, minimal values of longitudinal horizontal linear-stiffness of piers which are suitable for these three kinds of layout forms, and the values are 1000,800 and 1600 kN/cm·double-line respectively.

scholarly journals Experimental Study of the Influence of Extremely Repeated Thermal Loading on a Ballastless Slab Track-Bridge Structure

2020 ◽  
Vol 10 (2) ◽  
pp. 461 ◽  
Author(s):  
Lingyu Zhou ◽  
Tianyu Wei ◽  
Guangchao Zhang ◽  
Yingying Zhang ◽  
Mahunon Akim Djibril Gildas ◽  
...  
Keyword(s):  
Thermal Loading ◽  
Reduction Rate ◽  
Railway Track ◽  
Track Structure ◽  
Structural System ◽  
Loading Test ◽  
Slab Track ◽  
Loading Tests ◽  
Three Stages ◽  
Track Bridge

To study the initiation and expansion of the interlayer gap of the China Railway Track System Type II (CRTS-II) ballastless slab track structure under the action of repeated thermal loading as well as the influence of the interlayer gap on the displacement, strain and stiffness of the track structure, a 1/4 scale three-span ballastless slab track simply supported bridge structural system specimen was developed and 18 cycles of extremely thermal loading tests were carried out. Static loading tests were carried out before and after the repeated thermal loading test and the effects of the repeated temperature loading on the mechanical properties of the structural system were analyzed. The test results show that under repeated temperature loading, there is a gap between the track slab and cement emulsified asphalt (CA) mortar near the fixed end section of the beam (close to the shear slots). The interlayer gap gradually expands to the mid-span section in a “stepped” shape in three stages: initiation, expansion and stabilization. Under the same temperature load, the camber of the concrete box beam decreases gradually while that of the track structure increases gradually with the increase of the interlayer gap length. During the three stages of interlayer gap development, the track structure stiffness degrades gradually, and the fastest reduction rate during the expansion stage. At the end of the 18th cycle of thermal loading, a degradation of 14.96% and 2.52% is observed in the stiffness of the track structure and that of the ballastless track-bridge structural system, respectively.

Description of Subway DT Series Fastening

2014 ◽  
Vol 644-650 ◽  
pp. 535-538
Author(s):  
Wei Ping Wang ◽  
Dun Jin Cai ◽  
Xu Feng Ma ◽  
Ping Wang
Keyword(s):  
High Speed ◽  
Rail Transport ◽  
Railway Track ◽  
Track Structure ◽  
Large Space ◽  
High Speed Railway ◽  
Urban Rail ◽  
Subway System ◽  
Speed Up ◽  
Rail Structure

In recent decades, with the acceleration of population flowing in China, large and medium-sized cities to speed up the construction of urban rail. Relatively high speed railway, the requirement of the urban rail is relatively low, so it can be designed on the basis of high speed railway track structure for urban rail transport, this gives the designer the design of large space;Each city urban rail structure more or less differences. Especially fastening system is various, even in the same line also exist different fastening systems.Because Chinese fastening system in the subway is various, not a fixed is widely used fastening system;This paper, the DT series fastening in subway system has carried on the simple summary. Make a reference for fastening researchers.

Natural Vibration Analysis of High-Speed Railway Slab Tracks under Rail Longitudinal Force

2013 ◽  
Vol 706-708 ◽  
pp. 1443-1449 ◽  
Author(s):  
Yi Shi Guo ◽  
Zu Jun Yu ◽  
Hong Mei Shi
Keyword(s):  
High Speed ◽  
Natural Vibration ◽  
Longitudinal Force ◽  
Frequency Equation ◽  
Railway Track ◽  
High Speed Railway ◽  
Slab Track ◽  
Specific Effects ◽  
Coupling Dynamics ◽  
Dynamics Problems

The slab track is the main structure of the high-speed railway track, the Inherent dynamic characteristics of which is of great significance to the research on the Vehicle-Track Coupling Dynamics. The assumptions of the modal function describing the natural vibration of the track is a necessary theoretical basis in analytic and numerical calculations for dynamics problems, which is more in accordance with the real situation, the more likely characteristic estimation are to be accurate. In this paper, with the method of combine matrix, the system characteristic equation of slab-track model is deduced, and the exact analytic formulas of frequency equation and modal function are obtained. Meanwhile the specific effects of the Rail longitudinal force on the vibration performance of the tracks are analyzed through instances. The results show that this approach is an effective analytic method, the solution of which is accurate. And the track parameters can be flexibly initialized, which is especially applicable for the condition of track parameters varying and longitudinal strain with distribution.

Research and Progress on CA Mortar Emulsifying Asphalt of Ballast-Less Slab Track

2011 ◽  
Vol 239-242 ◽  
pp. 2399-2402 ◽  
Author(s):  
Ming Chao Qi ◽  
Xiao Xuan Li ◽  
Zhong Qi Jia
Keyword(s):  
Primary Structure ◽  
High Speed ◽  
Track Structure ◽  
Structure Form ◽  
High Speed Railway ◽  
Slab Track ◽  
Ca Mortar

Ballast-less slab track is the primary structure form of the modern high-speed railway, and cements phalt mortar is the most important component of flexible adjusting layer of slab track structure. This article introduces simply development and application of ballast-less track，then detailed explain the production and research of cements phalt mortar special asphalt lotion .

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