• Title/Summary/Keyword: Track Deterioration

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The Use of Bituminous Subballast on Future High-Speed Lines in Spain: Structural Design and Economical Impact

  • Teixeira, P.F.;Ferreira, P.A.;Pita, A. Lopez;Casas, C.;Bachiller, A.
    • International Journal of Railway
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    • v.2 no.1
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    • pp.1-7
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    • 2009
  • The development of structural solutions for high-speed or very high-speed tracks that minimize total life cycle costs of the system is a key issue to improve the operational profitability of new investments. In opposition to conventional ballasted tracks, slab track solutions can be a cost-effective solution, but only in the cases where the benefits due to the increase in track availability and the reduction of track maintenance offsets its much higher construction costs. In the cases where such investment is not feasible, it is worth to evaluate possible structural improvements to ballasted track that allow reducing its maintenance needs without increasing too much its construction costs. This paper evaluates the design requirements and the impact of improving conventional high-speed ballasted tracks by using a bituminous subballast layer. It is divided into two main parts: first the design requirements of the structural solutions with bituminous subballast and its possible benefits on high-speed track deterioration, and secondly the evaluation of the economic impact, in terms of construction costs, of using this structural solution material in future Spanish high-speed lines.

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The Displacement Limit at the End of an Approach Slab for a Railway Bridge with Ballastless Track (콘크리트궤도 부설 교량의 접속슬래브 단부 처짐한도에 관한 연구)

  • Choi, Jin-Yu;Yang, Shin-Chu
    • Journal of the Korean Society for Railway
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    • v.11 no.2
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    • pp.195-202
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    • 2008
  • The transition area between a bridge and an earthwork is one of the weakest area of track because of the track geometry deterioration caused unequal settlement of backfill of abutment. In case of a ballastless track, the approach slab could be installed to prevent such a phenomenon. But, if there is occurred the inclined displacement on the approach slab by a settlement of the foundation or formation, the track is also under the inclined displacement. And this defect causes reducing the running stability of a vehicle, the riding comfort of passengers, and increasing the track deteriorations by excessive impact force acting on the track. In this study, parametric studies were performed to investigate the displacement limit on the approach slab to avoid such problems. The length and the amount of unequal settlement of approach slab were adopted as parameter for numerical analysis considering vehicle-track interaction. Car body accelerations, variations of wheel force, stresses in rail, and uplift forces induced on fastener clip were investigated. From the result, resonable settlement limit on the end of an approach slab according to slab length was suggested.

Natural Frequency Analysis of Sleeper Floating Track System using Modal Test Technique (모달시험기법을 이용한 침목플로팅궤도의 고유진동수 분석)

  • Jung-Youl Choi
    • The Journal of the Convergence on Culture Technology
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    • v.10 no.3
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    • pp.833-838
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    • 2024
  • The urban railway sleeper floating track(STEDEF) is a structure that structurally separates the sleepers and the concrete bed using sleeper boots and resilience pads to reduce vibration transmitted to the concrete bed. Recently, the resilience pads of sleeper floating tracks that have been in use for more than 20 years are deteriorating. Accordingly, in order to evaluate the performance of the resilience pad, a static spring stiffness test is being performed after extracting the resilience pad. This evaluation technique is performed after replacing the resilience pad in use. However, the track natural frequency can change depending on the resilience pad spring stiffness and the uplift and subsidence of the concrete bed. In this study, modal testing technique was used to evaluate the track natural frequency. For this purpose, the sleeper boots material, resilience pad spring stiffness, and track natural frequency according to concrete bed uplift and subsidence were measured using modal tests at a laboratory scale. It was analyzed that the natural frequency of the sleeper floating track was directly affected by changes in the spring stiffness of the resilience pad. In addition, the change in natural frequency due to the uplift and subsidence of the concrete bed was also found to be large. Therefore, it is believed that the modal test technique presented in this study can be used to evaluate the resilience pad deterioration and voided sleepers.

A study on the characteristic of ballast fracture by M.T.T. works (MTT작업에 의한 도상자갈 파쇄특성에 관한 연구)

  • Lee, Choon-Kil;Kim, Nam-Hong;Woo, Byoung-Koo;Kim, Yong-Hyok;Kim, Kwan-Hyung;Lee, Sung-Wook
    • Proceedings of the KSR Conference
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    • 2008.06a
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    • pp.268-273
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    • 2008
  • The ballast, one of track components, plays an essential role as intermedium in transmitting train load to subgrade safely, and the deterioration of ballast directly effects the growth of track irregularity. So far, gravel fining of ballast track was mainly related to the repetition of train loads, but was gradually increased with using MTT(Multiple Tie Tamper) recently. Therefore, in this study, an evaluation of the abrasion and crush process of ballast particles was performed with outdoor field test by MTT works. From this study, the amount of abrasion and crush of ballast particles appeared to increase linearly with MTT works, and the gradient of particle size distribution curve appeared to deviate gradually from a criterion of aggregated ballast size distribution in high-speed railroad.

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The effect of Mobile Flash Butt Welding (이동식 플래시 버트 용접의 효과)

  • Lee Jun-Sik;Lee Jong-Su;Lee Hak-Kyu;Lee Jung-Kwon;Lee Jee-Ha
    • Proceedings of the KSR Conference
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    • 2004.10a
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    • pp.793-799
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    • 2004
  • In track a third weakness point is joint part, turnout part, curve part. One of them joint part of rail have been known to the most weak point by loosen of joint bar and fish bolt due to impulse and vibration by wheel contact at times. In addition happen to deformation and failure at end of rail, failure and miniature of ballast gravel. Finally impact between wheel and rail become origin cause of a welded rail, noise and vibration. riding condition deterioration, besides track failure. In the present domestic, Thermite and Gas pressure weldings have been used to continuous welded rail(CWR), however stiffness and confidence in quality is lower than Flash butt welding method. FRW have the excellent capacity, however have a shortcoming large scale of machine and power equipment. Therefore we will introduce Mobile Flash Butt Welder can weld in track.

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Dynamic responses of track according to the hardening of rail-pad (레일패드의 경화에 따른 궤도의 동적응답 변화 특성 분석)

  • Yoon, Tae-Hyoung;Choi, Jin-Yu;Yang, Shin-Chu;Kim, Eun
    • Proceedings of the KSR Conference
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    • 2006.11b
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    • pp.454-459
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    • 2006
  • A wheel force becomes large as increasing the stiffness of rail-pad, and it accelerates the deterioration of track, and it leads the maintenance cost rising. So, it is required to determine an appropriate replacement period for rail-pad. As a preliminary study to determine it, a numerical analysis was conducted to investigate the influence on a track behavior by the hardening of rail-pad. From the analysis, one knows that the dynamic wheel force is vary depend on the stiffness of rail-pad and the running speed of vehicle, the displacement and acceleration of rail is decreasing as increasing stiffness of rail-pad, and the displacement and acceleration increased in proportion to the rail-pad stiffness increasing.

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Evaluation on Fatigue Behavior of Resilience pad for Sleeper Floating Track System in Urban Transit (도시철도 침목플로팅궤도(STEDEF)의 침목방진패드 피로거동 분석)

  • Choi, Jung-Youl;Lee, Jeong-Sug;Bong, Jae-Geun;Kim, Su-Jin;Chung, Jee-Seung
    • The Journal of the Convergence on Culture Technology
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    • v.6 no.3
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    • pp.347-352
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    • 2020
  • In this study, the variation of track impact factor according to the spring stiffness change rate of sleeper resilience pad was analyzed based on field measurements. In addition, the correlation between field measurement results and 7 million fatigue test results was verified. The fatigue effect diagram of the sleeper resilience pads was presented considering the nonlinear deterioration characteristics of the sleeper resilience pads used for the STEDEF track. Based on the field measurement results, the nonlinear characteristics of the track impact factor for the spring stiffness change rate over 30% of sleeper resilience pad on the track impact factor-track support stiffness diagram were analyzed to be consistent with the fatigue test results.

A study on availability of GPR in estimating the condition of ballast (자갈도상 상태평가를 위한 GPR기법의 적용성 분석)

  • Lee, Choon-Kil;Kim, Nam-Hong;Woo, Byoung-Koo;Kim, Kwan-Hyung
    • Proceedings of the KSR Conference
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    • 2007.11a
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    • pp.494-499
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    • 2007
  • The ballast, one of a track components, plays an essential role as intermedium in transmitting train traffic-load to subgrade safely, and deterioration of ballast caused by cumulative load effects growth of track irregularity. Especially in the case of Gyeongbu high-speed railway, the deteriorating speed of ballast by dynamic vibration is faster than conventional line because KTX is longer than normal trains in length and it's velocity is very fast with high speed of 300km/h as well. In addition, ballast is a nonlinear material contrary to ordinary metal which has homogeneous property and this property of ballast may cause transformation of ballast. Therefore the theoretical modeling of ballast is quite complicated and it is hard to ensure the reliability of the result. The objective of this paper is to examine the availability of GPR(Ground Penetrating Radar) in estimating the thickness and the degree of deterioration of ballast. First, We figured out the principle of GPR which is the technique of evaluating the condition of ballast and then analyzed data which were measured at Gyeongbu high-speed railway where KTX is running now.

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Deterioration of Hiking Trails at Great Walksin New Zealand - Case Study on Tongariro Alpine Crossing, Routeburn, and Kepler Tracks - (뉴질랜드 그레이트 워크스의 탐방로 훼손 - 통가리로 알파인 크로싱, 루트번 및 케플러 트랙을 사례로 -)

  • Kim, Taeho
    • Journal of The Geomorphological Association of Korea
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    • v.24 no.4
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    • pp.103-115
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    • 2017
  • This paper shows the types of deteriorated hiking trails and degrading factors at three Great Walks such as Tongariro Alpine Crossing, Routeburn Track and Kepler Track in New Zealand. The deteriorated trails could be classified into gullying, widening, narrowing, branching and sidewall erosion. Department of Conservation carefully manages overland flows on trails for preventing surface erosion, thus the Great Walks show only a minor problem of gully on trails which is usually active in a mountainous area. Widening and branching of trails caused by tread erosion are not also developed due to the restriction of visitors as well as the management of rainwash. However, despite the detailed maintenance and prevention of an overuse of trails, some trails traversing steep slopes in a alpine zone under a periglacial environment are severely degraded along their sidewalls. It suggests that a unvegetated sidewall of trails has to be strictly managed in an early stage of occurrence and a slope-traversing section should be selected with more consideration when establishing a route of hiking trails.

Evaluation on Damage Effect of Concrete Track induced by Underground Structure Displacement Behavior (지하구조물 변위거동에 따른 콘크리트궤도의 손상영향 분석)

  • Jung-Youl Choi
    • The Journal of the Convergence on Culture Technology
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    • v.10 no.3
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    • pp.839-844
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    • 2024
  • This study analytically analyzed the impact of underground structure displacement behavior on track damage due to adjacent excavation work, ground deterioration, and changes in groundwater level. The concrete track that was the subject of the study was analyzed for sleeper floating track(STEDEF) and precast concrete slab track(B2S). Sleeper floating track is a track structure in which the concrete bed and sleepers are voided. precast concrete slab track is a track structure that induces the elastic behavior of the rail by assembling rails and fasteners using slabs. For numerical analysis, each concrete track, from rail to concrete bed, was modeled as three-dimensional elements. In addition, the displacement behavior of the underground structure was set as a variable to analyze the damage effect on the concrete bed. Using numerical analysis, the concrete bed stress due to uplift and subsidence was analyzed, and the level of crack effect was analyzed by comparing it to the tensile strength and shear strength. As a result of the analysis, it was found that the sleeper floating track was more vulnerable than the precast concrete slab track when the same uplift and subsidence occurred. In addition, uplift and subsidence, it was analyzed that the cracks range in the sleeper floating track was large.