• Title/Summary/Keyword: railway ballast

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The Effect and Countermeasures of The Vertical Track Settlement Caused by Expand and Contract Behavior of the High-Speed Railway Bridge Girder (고속철도 교량상판의 온도신축작용이 궤도처짐에 미치는 영향과 대책에 관한 연구)

  • 강기동
    • Journal of the Korean Society for Railway
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    • v.7 no.3
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    • pp.283-289
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    • 2004
  • According to continuos welded rails on a bridge, temperature changes bring about the expansion of the bridge deck adding axil forces on the track. Moreover, the ballast on the bridge deck expansion joint is moved due to the bridge deck. If bridge decks are longer, the influence is greater, loosening ballast, causing track irregularities, and deteriorating passengers' comfort. Considering structure of bridge itself and tolerance of track irregularities caused by the loosened ballast on bridges, the maximum length of a deck should be less than 80m, which is the same as the standard of the French railway. In this study, an interaction between the expansion related to the bridge length and irregularity in longitudinal level referring to measurements and maintenance works performed in the high-speed railways was analyzed. This research shows that installation of sliding plate or vertical ballast stopper is not a good option since it is difficult to install. On the other hand, installation of movable fastener or gluing is easy but its influence is insignificant. To conclude, switch tie tamping or manual tamping is more effective than others.

An Estimate of Ballast Track Condition on Dynamic Behavior of Railway Bridge (철도교량의 동적거동 특성을 고려한 자갈도상궤도의 상태추정에 관한 연구)

  • Kweon, Oh-Soon;Choi, Jung-Youl;Kang, Myoung-Seok;Lee, Hee-Up;Park, Yong-Gul
    • Proceedings of the KSR Conference
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    • 2007.11a
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    • pp.480-493
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    • 2007
  • Many railway-advanced countries are using the various types of track to reduce the track maintenance and repair cost according to the improvement of velocity. It spends on much maintenance and repair cost for ballast track due to abrasion of ballast, track irregularity and unisotropical ballast-support stiffness. The ballast track on railway bridge is accelerating the deterioration of ballast according to interaction of railway bridge and track. As continuing the deterioration, it is caused dynamic loads. Due to these effects, it increases negative loads of track and bridge. However, when designing the railway bridge, the effect of ballast track was applicate only dead load, so elastic behavior effect of ballast track is not influenced. Therefore, this paper presumes the stiffness of ballast track on railway bridge considering dynamic behavior of railway bridge, it was evaluated that effect on dynamic behaviors of railway bridge according to ballast track stiffness.

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Research for Assessing Railway Trackbed Condition (궤도하부구조의 상태 평가를 위한 연구)

  • Kim Dae-Sang;Lee Su-Hyung;Kang Seung-Goo;Son Kang-Hee
    • Proceedings of the KSR Conference
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    • 2004.06a
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    • pp.980-986
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    • 2004
  • So far systematic and reliable methods for the investigation of track substructure (ballast and subgrade) are not developed yet. This study presents the applicability of GPR (Ground Penetrating Radar) and PBS (Portable Ballast Sampler) to the evaluation of railway trackbed conditions. Including FWD (Falling Weight Deflectometer) often used to evaluate the subsurface conditions of pavement, the standard system for assessing trackbed conditions will be developed in the future.

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Economic Assesment for Track Ballast Structures based on Proper Maintenance Level (적정 유지관리수준에 기초한 궤도도상구조에 대한 경제성 검토)

  • Baek, Jae-Wook;Joo, Hwan-Joong;Song, Yoo-Seob;Park, Tae-Hyo
    • Journal of the Korean Society for Railway
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    • v.10 no.2 s.39
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    • pp.167-178
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    • 2007
  • In general, it is known that the concrete ballast track is possible to reduce a cost of maintenance activities cause of maintenance free by restrictive maintenance in application of track ballast structures. However, if deteriorations and fracture mechanism of a material are considered, proper maintenance activities and repairing are continually required. For the problems, we evaluated an economical efficiency of the gravel ballast and the concrete ballast on a proper level of maintenance activities. As the method based on history path is difficult to obtain sufficient reliabilities cause of an absence of real data for maintenance activities, we chose the delphi survey method by professional group, and we obtained the appropriate index and profiles for maintenance activities. As a result, we founded that effects for cost reduction can be expected by preventive maintenance management, and we proposed economical restrictions and life cycle cost for track ballast structures in a life cycle.

Variation of Lateral Ballast Resistance due to Ballast Work (도상직업에 의한 도상 횡저항력 변화)

  • Lim Nam-Hyoung;Hwang Sung-Ho;Lee Jee-Ha;Yang Shin-Chu
    • Proceedings of the KSR Conference
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    • 2004.06a
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    • pp.961-966
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    • 2004
  • Lateral ballast resistance is one of track components that causes much effects in track buckling. Ballast work or tie renewal if is done the ballast original lateral resistance lose. Reduction of lateral ballast resistance may significantly reduce the stability of track. Lateral ballast resistance that is decreased by these work increases slowly according to the increase of train passing tonnage. We measured the ballast lateral resistance in Okchon station neighborhood in Seoul-Busan line to grasp fluctuation phenomenon of ballast resistance by ballast class-2 work. The rate of decrease of ballast lateral resistance shortly after ballast work and the rate of increase by increase of train passing tonnage were investigated.

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Study on the stresses distribution of ballast bed using DEM (Discrete Element Method) Analysis (DEM을 이용한 자갈도상의 응력분포에 관한 연구)

  • Kim Dae-Sang;Lee Su-Hyung;Lee Sung-Hyuk;Lee Sang-Bae
    • Proceedings of the KSR Conference
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    • 2005.11a
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    • pp.878-883
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    • 2005
  • Sleeper, the ballast, and ballast mat in the high-speed railroad line are modelled using a two-dimensional discrete element method to generate circle and line elements. Stress transfer mechanism from the sleeper to the subgrade via the ballast is analyzed. The behavior of ballast bed of the high-speed railroad line is also accessed with the model.

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Ballast Flying Probability Analysis for Ballast Types and Underbody Flow Conditions (자갈 종류 및 하부 유동 조건에 따른 자갈비산 확률 분석)

  • Rho, Joo-Hyun;Ku, Yo-Cheon;Yun, Su-Hwan;Park, Hoon-Il;Kwon, Hyeuk-Bin;Lee, Dong-Ho
    • Journal of the Korean Society for Railway
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    • v.12 no.6
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    • pp.829-834
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    • 2009
  • A ballast-flying probabilitie is suggested for various ballast types, heighter types and underbody flow conditions as train speeds. The average speed of measured points is converted to the ballast-flying probabilities of BFPF which come from wind tunnel test data. Underbody flow fields are numerically simulated for the various conditions. The results show that the ballast-flying probability is steeply increased as train speed increased, and reaches a value of 87% at 350 km/h train speed. And the differences of probabilities among the ballast shapes are considerably high. The upper surface of heighter or tie is most probable area. Through this study, the ballast-flying Sensitivities with heighter was defined to understand the characteristics of ballast-flying probability on various conditions. And the ballast-flying probability can be reduced by the heighter.

A study for CWR on Steel Plate Girder Railway Bridge without Ballast (무도상 교량 특성을 고려한 장대화 방안에 관한 연구)

  • Min Kyung-Joo;Nam Bo-Hyun;Ban Geol yeong
    • Proceedings of the KSR Conference
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    • 2005.05a
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    • pp.706-711
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    • 2005
  • From the using CWR (Continuously Welded Rail) on steel plate girder bridges without ballast, axial forces are occurred from a temperature on CWR and girders. Because of the additional axial forces, studies in order to CWR and developments of devices are proceeding. The track system of steel plate girder bridges is poor. When CWR is used for the system, the resistance on sleepers is increased from a temperature. So it is increasing an effect on CWR and, for solving the effect, longitudinal forces for buckle are being decreased. It is possible that opposite cases can be happened and it is also compared and studied. Therefore, we present a reasonable model for analyzing CWR within the property of steel plate girder railway bridges in Korea. Furthermore, the results analyzed for stability is compared and evaluated with tests. Finally, a reasonable method for the installation of CWR on bridges without ballast is suggested.

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Evaluation of the status of subgrade of high speed railway using HWAW method (HWAW방법을 이용한 고속철도 하부 노반 평가)

  • Park, Hyung-Choon;Park, Jin-O;Jin, Nam-Hui;Noh, Hee-Kwan;Bae, Hyun-Jung
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.03a
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    • pp.208-212
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    • 2010
  • The high-speed railway consists of tracks, gravel ballast and subgrade, and the dynamic load is passed to subgrade through track and gravel ballast. The relaxation condition of the gravel ballast is able to be evaluate relatively and to be repaired through a continuous management, but it is difficult to evaluate the condition of subgrade, which is final part of supporting dynamic load and to repair it when made a problem. The gravel ballast and subgrade are evaluated by determining shear wave velocity. To evaluate ballast and subgrade, a good method to determine shear wave velocity is a non-destructive experiment such as surface wave tests providing a prompt experiment because an experiment in railway has a lot of tests which are carried out following railway directions and needs to prevent damage of the system. In general, a railway has limitation of an experimental space by narrow width, sleeper and etc., and background noise by a reflector exists. The existing surface wave tests need a minimum space, and it is difficult to get a reliable test results on account of background noise effect. Therefore, it is difficult or impossible to apply to existing surface wave test of subgrade and ballast. In this study, the HWAW method is applied to determine a shear wave velocity profile of the underground. The HWAW method is the experiment which is able to be carried out on a narrow space, and it determines share wave velocity of a site by measuring the wave from surface sources on the same spot. In addition, it removes effects of background noise accordingly to a signal processing using harmonic wavelet transforms, so it is useful to evaluate subgrade of a high-speed railway in the narrow space and the situation of background noise. In order to check an application of the HWAW method, an experiment is carried out on a high-speed railway field and a test result is compared to boring results.

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A Study on the Dynamic Behaviors of Ballast Track using Field Test (현장측정을 통한 자갈도상 궤도의 동적 거동 분석)

  • Choi, Jung-Youl;Park, Kyun-Seo;Ryu, Joong-Youl;Park, Jeong-Gun;Ryu, Kyoung-Sik;Park, Yong-Gul
    • Proceedings of the KSR Conference
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    • 2006.11b
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    • pp.494-507
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    • 2006
  • The major objective of this study is to investigate the dynamic behaviors of track due to the deterioration characteristics of ballast for servicing tracks by the field test. The durability of ballast plays an important role in the track behaviour. To estimate the deterioration characteristics of ballast, several tests have been carried out by several scholars. The deterioration characteristics of ballast is one of the most important factor in the dynamic behaviour of track and its life. In this paper abrasion/breakage characteristics of ballast is studied to predict the effect of physical ballast characteristics on ballast track. To reveal deterioration characteristics of ballast, the field test were carried out. The deterioration characteristics, studied in this paper, is applied to the dynamic behaviour of track in various conditions.

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