• Title, Summary, Keyword: Rail Stability

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Stability Evaluation of Track on Conventional Line According to Traveling Tilting Train (틸팅차량 주행에 따른 기존선 궤도의 주행안정성 평가)

  • Park, Yong-Gul;Eum, Ki-Young;Choi, Jung-Youl;Sung, Deok-Yong
    • Journal of the Korean Society for Railway
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    • v.10 no.6
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    • pp.701-708
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    • 2007
  • A tilting train, which was developed to run the curve section without reducing the speed and compromising the riding quality, can improve the speed so as to reduce the travel time, compared to the existing trains. Then the force generated by the train operation to the track is in proportion to train operation speed, which means the track shall bear the increased force as much as the increase in train operation speed. Particularly, wheel load and lateral wheel load generated by train operation and distributed to the rail tend to cause the track to suffer the strain and furthermore the severe disaster such as derailment. To deal with such problem and ensure the train will run safety and stably, the tolerance in wheel load change, lateral wheel load and derailment coefficient was determined for quantitative evaluation of the train operation stability. In this study, derailment coefficient of inner and outer rail at existing curve section of tilting train was determined to evaluate the curve radius, possibility of acceleration and the need of rail improvement, which was then compared with the existing traditional train and high speed train. Conducting the quantitative evaluation of dynamic wheel load and lateral wheel load of each train, which was based on field survey, derailment coefficient and static & dynamic wheel load change, which serve the evaluation criteria of train operation stability, were determined for comparison with the standards, thereby analyzing the stability of the tilting train.

The Reinforcement Effect of Woven Geotextiles for Railway Roadbed High-Embankment on Soft Ground by the Limit Equilibrium Analysis (한계평형해석에 의한 연약지반 위의 철도노반 고성토를 위한 직포 보강 효과)

  • Kim, You-Seong;Choi, Jae-Seon
    • Journal of the Korean Geosynthetics Society
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    • v.9 no.4
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    • pp.27-37
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    • 2010
  • Woven geotextiles (polyester mats) reinforcement is generally used to improve traffic ability, bearing capacity, and slope stability for embankment construction on soft ground. Cases of two high-strength woven geotextiles reinforcement layers are introduced in the present paper, which has been successfully constructed for rail road embankment on soft ground. According to the case results based on the limit equilibrium analyses of slope stability, the two high-strength woven geotextiles reinforcement layers on the soft ground can substantially increase the stability of the embankment by about 25%, improve the safety factor from 0.91 to 1.14, and significantly reduce the embankment construction duration at least 2 months. Therefore, the application of high-strength woven geotextiles is found to be useful for in-situ cases having the lack of construction duration and stability, as a soft ground improvement.

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Stability Analysis for CWR on the Railway Bridges by Linearized Method (선형해석법을 이용한 교량상 장대레일의 안정성 해석 방법 연구)

  • Choi, Young-Gil;Oh, Ju-Won
    • Journal of the Korean Society for Railway
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    • v.12 no.4
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    • pp.472-480
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    • 2009
  • The stability analysis for CWR is difficult in the theory itself because both geometric and material nonlinearity should be considered. Also the analysis results are varied according to the loading history. In contrast to the complexity in the theory, the analysis results for CWR on the railway bridges are quite simple and can be predicted because of a small buckling effect and its negligible nonlinearity. In this study, refined nonlinear analysis methods for the stability analysis of CWR on the railway bridges were developed which consider only material nonlinearity beeause the effects of geometric nonlinearity are nominal. In this study, the analysis results can be found within limited number of iterations with idealized linear force-displacement relationship. From the analysis result comparisons, it was found that the stability analysis for CWR on the railway bridges can be performed effectively by this method.

A Study on the Design of Small-Scaled Derailment Simulator considering Similarity Rules (상사법칙을 고려한 소형탈선시뮬레이터 설계에 관한 연구)

  • Eom, Beom-Gyu;Lee, Se-Yong;Oh, Se-Been;Kang, Bu-Byoung;Lee, Hi-Sung
    • Proceedings of the KSR Conference
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    • pp.1085-1091
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    • 2011
  • The dynamic stability of railway vehicle has been one of the important issues in railway safety. The dynamic simulator has been used in the study about the dynamic stability of railway vehicle and wheel/rail interface. Especially, a small scale simulator has been widely used in the fundamental study in the laboratory instead of full scale roller rig which is not cost effective and inconvenient to achieve diverse design parameters. But the technique for the design of the small scale simulator for the fundamental study about the dynamic characteristics of the wheel-rail system and the bogie system has not been well developed in Korea. Therefore, the research about the development of the small scale simulator and the bogie has been conducted. This paper presents the design of the small-scaled derailment simulator and the example design case of a small scale bogie. The simulator could be used in the study about the effect of diverse parameters such as attack angle, wheelbase and cant on dynamic behavior of the bogie and the safety parameter such as derailment coefficient and critical speed.

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Design of Small-Scaled Derailment Simulator for Investigating Bogie Dynamics

  • Eom, Beom-Gyu;Kang, Bu-Byoung;Lee, Hi-Sung
    • International Journal of Railway
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    • v.4 no.2
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    • pp.50-55
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    • 2011
  • The dynamic stability of railway vehicle has long been one of the important issues in railway safety. The dynamic simulator has been used as a tool for investigating the dynamic stability of railway vehicles and wheel/rail interfaces. In particular, small scale simulators have been widely used in laboratory studies instead of full scale roller rigs which can be quite costly and rather inconvenient for testing out the effect of diverse design parameters. But techniques for design of a small scale simulator for the fundamental study about the dynamic characteristics of the wheel-rail systems and the bogie systems have not been well developed in Korea. Therefore, a research on the development of a small scale simulator for investigating bogie dynamics needs to be undertaken. The present paper investigates design of a small-scaled derailment simulator and the design of a small scale bogie. The simulator developed can be used to investigate the effect of diverse parameters such as attack angle, wheelbase and cant on dynamic behavior of the bogie and key dynamic performance parameters such as derailment coefficient and critical speed.

Monitoring in-service performance of fibre-reinforced foamed urethane sleepers/bearers in railway urban turnout systems

  • Kaewunruen, Sakdirat
    • Structural Monitoring and Maintenance
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    • v.1 no.1
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    • pp.131-157
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    • 2014
  • Special track systems used to divert a train to other directions or other tracks are generally called 'railway turnout'. A traditional turnout system consists of steel rails, switches, crossings, steel plates, fasteners, screw spikes, timber bearers, ballast and formation. The wheel rail contact over the crossing transfer zone has a dip-like shape and can often cause detrimental impact loads on the railway track and its components. The large impact also emits disturbing noises (either impact or ground-borne noise) to railway neighbors. In a brown-field railway track where an existing aged infrastructure requires renewal or maintenance, some physical constraints and construction complexities may dominate the choice of track forms or certain components. With the difficulty to seek for high-quality timbers with dimensional stability, a methodology to replace aged timber bearers in harsh dynamic environments is to adopt an alternative material that could mimic responses and characteristics of timber in both static and dynamic loading conditions. A critical review has suggested an application of an alternative material called fibre-reinforced foamed urethane (FFU). The full-scale capacity design makes use of its comparable engineering characteristics to timber, high-impact attenuation, high damping property, and a longer service life. A field trial to investigate in-situ behaviours of a turnout grillage system using an alternative material, 'fibre-reinforced foamed urethane (FFU)' bearers, has been carried out at a complex turnout junction under heavy mixed traffics at Hornsby, New South Wales, Australia. The turnout junction was renewed using the FFU bearers altogether with new special track components. Influences of the FFU bearers on track geometry (recorded by track inspection vehicle 'AK Car'), track settlement (based on survey data), track dynamics, and acoustic characteristics have been measured. Operational train pass-by measurements have been analysed to evaluate the effectiveness of the replacement methodology. Comparative studies show that the use of FFU bearers generates higher rail and sleeper accelerations but the damping capacity of the FFU help suppress vibration transferring onto other track components. The survey data analysis suggests a small vertical settlement and negligible lateral movement of the turnout system. The static and dynamic behaviours of FFU bearers appear to equate that of natural timber but its service life is superior.

The Evaluation of Axial Stress in Continuous Welded Rails via Three-Dimensional Bridge-Track Interaction

  • Manovachirasan, Anaphat;Suthasupradit, Songsak;Choi, Jun-Hyeok;Kim, Bum-Joon;Kim, Ki-Du
    • International journal of steel structures
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    • v.18 no.5
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    • pp.1617-1630
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    • 2018
  • The crucial differences between conventional rail with split-type connectors and continuous welded rails are axial stress in the longitudinal direction and stability, as well as other issues generated under the influence of loading effects. Longitudinal stresses generated in continuously welded rails on railway bridges are strongly influenced by the nonlinear behavior of the supporting system comprising sleepers and ballasts. Thus, the track structure interaction cannot be neglected. The rail-support system mentioned above has properties of non-uniform material distribution and uncertainty of construction quality. The linear elastic hypothesis therefore cannot correctly evaluate the stress distribution within the rails. The aim of this study is to apply the nonlinear finite element method using the nonlinear coupling interface between the track and structural model and to illustrate the welded rail behavior under the loading effect and uncertain factors of the ballast. Numerical results of nonlinear finite analysis with a three-dimensional solid and frame element model are presented for a typical track-bridge system. A composite plate girder, modeled by solid and shell elements, is also analyzed to consider the behavior of the welded rail. The analysis result showed buckling under the independent calculations of load cases, including 'temperature change', 'bending of the supporting structure', and 'braking' of the railway vehicle. A parametric study of the load combination method and the loading sequence is also included in this analysis.

Structural Optimization for a Jaw Using the Kriging model (이단계 크리깅 모델을 이용한 조(Jaw)의 구조최적설계)

  • Lee, Kwon-Hee;Bang, Il-Kwon;Kang, Dong-Hun;Han, Dong-Seop;Han, Geun-Jo
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • v.2
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    • pp.143-147
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    • 2006
  • The rail clamp is the device to prevent that a crane slips along rails due to the wind blast as well as locate the crane in the set position for loading and unloading containers. The wedge type rail clamp should be designed to consider the structural stability and the durability because it compresses both rail side with large clamping force by the wedge working as the wind speed increases. In this research, the kriging interpolation method using sequential sampling is utilized to find the optimum shape of the jaw in the rail clamp. The suggested method predicts more accurate response value than the response surface method. The optimum results obtained by the proposal method are compared with those by the commercial software.

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