A Parametric Study of Embedded Slab Track System for High-Speed Applications on Cohesive Subgrade

2021 ◽  
Author(s):  
Pranjal Mandhaniya ◽  
J. T. Shahu ◽  
Sarvesh Chandra
Keyword(s):  
Parametric Study ◽  
High Speed ◽  
Slab Track ◽  
Track System

High Speed Rail: Track Construction Considerations

2011 ◽  
Author(s):  
Blaine O. Peterson
Keyword(s):  
High Speed ◽  
Optimal Solution ◽  
Rolling Stock ◽  
High Speed Rail ◽  
Track Geometry ◽  
Slab Track ◽  
Passenger Rail ◽  
Construction Methods ◽  
Track System ◽  
Ballasted Track

This paper discusses general High Speed Rail (HSR) track geometry, construction and maintenance practices and tolerances. The discussion will reference several key international projects and highlight different construction methods and the track geometry assessments used to establish and ensure serviceability of a typical HSR system. Historically, established tighter tolerances of “Express” HSR (i.e. operating speeds greater than 240 km/h or 150 mph) systems have favored the use of slab track systems over ballasted track systems. Slab track systems offer greater inherent stability while ballasted track systems generally require more frequent track geometry assessments and anomaly-correcting surfacing operations. The decisions related to which system to use for a given application involve numerous considerations discussed only briefly in this paper. In many cases, the optimal solution may include both track forms. Rolling stock considerations and their influence on track infrastructure design are considered beyond the scope of this paper. This paper will focus predominantly on two slab track systems widely used in international HSR projects: the Japanese J-slab track system; and the German Rheda slab track system. The French track system will be referenced as the typical ballasted track HSR design. The practices discussed in this paper generally apply to systems which are either primarily or exclusively passenger rail systems. In the U.S., these types of systems will necessarily exclude the systems the Federal Railway Administration (FRA) refers to as “Emerging” or “Regional” HSR systems which include passenger train traffic to share trackage on, what are otherwise considered, primarily freight lines.

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.

scholarly journals Moving Element Analysis of High-Speed Train-Slab Track System Considering Discrete Rail Pads

2020 ◽  
pp. 2150014
Author(s):  
Tuo Lei ◽  
Jian Dai ◽  
Kok Keng Ang ◽  
Kun Li ◽  
Yi Liu
Keyword(s):  
Coordinate System ◽  
High Speed ◽  
Harmonic Wave ◽  
Equations Of Motion ◽  
Moving Frame ◽  
Iteration Algorithm ◽  
Vehicle Speed ◽  
Element Analysis ◽  
Slab Track ◽  
Track System

This paper presents a study of the dynamic behavior of a coupled train-slab track system considering discrete rail pads. The slab track is modeled as a three-layer Timoshenko beam. The study is carried out using the moving element method (MEM). By introducing a convected coordinate system moving at the same speed as the vehicle, the governing equations of motion of the slab track are formulated in a moving frame-of-reference. By adopting Galerkin’s method, the element stiffness, mass and damping matrices of a truncated slab track in the moving coordinate system are derived. The vehicle is modeled as a multi-body with 10 degrees of freedom. The nonlinear Hertz contact model is used to account for the wheel–rail interaction. The Newmark integration method, in conjunction with a global Newton–Raphson iteration algorithm, is employed to solve the nonlinear dynamic equations of motion of the vehicle–track coupled system. The proposed MEM model of the system is validated through comparison with available results in the literature. Further study is then made to investigate the vehicle–track system accounting for track irregularities modeled as short harmonic wave forms. Results showed that irregularities with short wavelengths have a significant effect on wheel–rail contact force and rail acceleration, and the dynamic response of the track structure does not increase monotonously with the increase of the vehicle speed.

Dynamic Analysis of Pitch Plane Railway Vehicle-Track Interactions Due to Single and Multiple Wheel Flats

2008 ◽  
Author(s):  
Rajib Ul Alam Uzzal ◽  
Subhash Rakheja ◽  
Waiz Ahmed
Keyword(s):  
Parametric Study ◽  
High Speed ◽  
Impact Load ◽  
Critical Length ◽  
Hertzian Contact ◽  
Railway Vehicle ◽  
Main Concern ◽  
Track System ◽  
Wheel Flat ◽  
The Impact

The dynamic impact forces due to the wheel defect such as a flat is a main concern for a heavy freight train operating at high speed. The present investigation employs a pitch plane vehicle model coupled with a comprehensive three-layer track system model to study the impact force generated in the wheel-rail interface due to the presence of wheel flats. The wheel-rail contact is modeled using nonlinear Hertzian contact theory. Responses in terms of wheel-rail impact load and forces transmitted to bearings, pad and ballast are evaluated in an attempt to identify desirable design and operating factors. Wheel-rail impact loads due to the presence of multiple flats either in single or different wheels in-phase or out-of-phase conditions are evaluated and analyzed. A detailed parametric study is carried out that includes the variations in selected vehicle, track, operational as well as flat parameters. The results show that the effect of multiple flats is insignificant if they are more than 45° apart. The impact due to single wheel flat can be larger than in-phase flats at each wheel due to the presence of pitch dynamics. The parametric study shows that other than speed, depth and length of the flats are most sensitive parameters, and there exists a critical length at each flat depth that leads to the largest impact load.

scholarly journals DYNAMIC PERFORMANCE OF LOW VIBRATION SLAB TRACK ON SHARED HIGH-SPEED PASSENGER AND FREIGHT RAILWAY

Transport ◽  
2018 ◽  
Vol 33 (3) ◽  
pp. 669-678
Author(s):  
Qinglie He ◽  
Chengbiao Cai ◽  
Shengyang Zhu ◽  
Jiawei Zhang ◽  
Wanming Zhai
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Vibration Isolation ◽  
Dynamic Models ◽  
Concrete Slab ◽  
Dynamic Performance ◽  
Tension Stress ◽  
Slab Track ◽  
Track System ◽  
Supporting Layer

This work investigates dynamic performance of a low vibration slab track on a shared high-speed passenger and freight railway, and an optimal modulus of the isolation layer (rubber pad) is proposed to meet the adaptability of the track system under the dynamic actions of high speed passenger and heavy axle-load freight trains. First, detailed finite element models of the slab track with and without the rubber pad between concrete slab and supporting layer are established by using software ANSYS. Further, coupled dynamic models of passenger/freight vehicle–low vibration/tradition slab track system are developed to calculate the wheel–rail forces, which are utilized as the inputs to the finite element model. Finally, the dynamic characteristics of the low vibration slab track, the specific function of the rubber pad, and the optimal modulus of the rubber pad are studied in detail. Results show that the interaction force between the freight vehicle and low vibration slab track is more significant because of the heavy axle-load, which leads to larger vertical stress amplitudes of each track layer. Whereas the accelerations of track components induced by the passenger vehicle are much larger than those induced by the freight vehicle, due to the much faster speed that can generate high wheel–rail interaction frequency. The rubber pad of the slab track does not play a role in attenuating slab vibration; instead it causes an increase of slab acceleration and its surface tension stress. However, the rubber pad can decrease the supporting layer acceleration and the slab compression stress, which plays a significant role in vibration isolation and buffers the direct impact force on the slab caused by vehicle dynamic load. To ensure a reasonable vibration level and dynamic stress of the slab track, the optimal modulus of the rubber pad is suggested to be 3÷7.5 MPa.

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.

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