• Title/Summary/Keyword: Track Deformation

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Analysis of Permanent Deformations in Asphalt Mixtures for Design of Asphalt Trackbed Foundation (철도 노반 설계를 위한 아스팔트 혼합물의 영구변형 특성 분석)

  • Lim, Yujin;Lee, JinWook;Lee, SeongHyeok;Lee, ByeongSik
    • Journal of the Korean Society for Railway
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    • v.17 no.2
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    • pp.123-132
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    • 2014
  • In this study, permanent deformation of asphalt trackbed was investigated by performing repetitive load test on specimen made with dense graded asphalt mixture that was specially prepared for asphalt trackbed foundation. The obtained test results were compared with those computed from the prediction model proposed by AASHTO 2002, called MEPDG. No prediction model adaptable only for permanent deformation of the asphalt trackbed foundation has yet been developed, so the prediction model by AASHTO was adapted in this study to simulate permanent deformation of trackbed foundations in asphalt slab track and in ballasted asphalt track. In order to simulate permanent deformation, a finite element analysis was performed to obtain stresses generated in trackbed due to wheel load. It was found that the predicted permanent deformation was much smaller than the anticipated deformation and that the asphalt track could be stable during the service life of the structure.

Deformation and Stress Distribution of Discontinuous Precast Concrete Track Slab : II. Stress Distribution (불연속 프리캐스트 콘크리트궤도 슬래브의 변형과 응력 분포 : II. 응력 분포)

  • Lee, Dong Hoon;Kim, Ki Hyun;Jang, Seung Yup;Zi, Goangseup
    • Journal of the Korean Society for Railway
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    • v.20 no.5
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    • pp.637-648
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    • 2017
  • In this paper, the effects of initial built-in deformation and temperature deformation on the stress distribution of discontinuous precast concrete track slab under train load were examined. According to the results, when train load is put on a precast concrete slab with initial built-in deformation and deformation due to temperature gradient, the maximum tensile stresses develop at the upper side of slab in the slab center, edge center and corner of shear pocket; the stress distribution is different from that of the case under train load only. Therefore, to accurately predict the actual weak points and failure modes, one should calculate the stress under train load considering the initial built-in and temperature deformation of the slab.

Evaluation of Track Irregularity Effect due to Adjacent Excavation on Serviced Railway Line (철도시설물 인접굴착공사에 따른 운행선 궤도의 궤도틀림 영향 평가)

  • Choi, Jung-Youl;Park, Dong-Ryong;Chung, Jee-Seung
    • The Journal of the Convergence on Culture Technology
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    • v.5 no.4
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    • pp.401-406
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    • 2019
  • The three-dimensional precision numerical analysis was performed using the finite element model applied with the railway track model consisting of rails, sleepers, and track elastic springs(ballast, rail pad). As a result of analyzing the track deformation level of the existing tracks due to the excavation work adjacent to the railway facilities, it was found that the track irregularity evaluation criteria (allowed values) of both conventional and high-speed railways lines were satisfied. Based on the numerical analysis using the track model, it was analyzed that the results of the prediction of the track irregularity due to the excavation work and the level of the track deformation occurring at the actual site could be approximated as closely as possible.

Estimation of track irregularity using NARX neural network (NARX 신경망을 이용한 철도 궤도틀림 추정)

  • Kim, Man-Cheol;Choi, Bai-Sung;Kim, Yu-Hee;Shin, Soob-Ong
    • Proceedings of the KSR Conference
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    • 2011.10a
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    • pp.275-280
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    • 2011
  • Due to high-speed of trains, the track deformation increases rapidly and may lead to track irregularities causing the track stability problem. To secure the track stability, the continual inspection on track irregularities is required. The paper presents a methodology for identifying track irregularity using the NARX neural network considering non-linearity in the train structural system. A simulation study has been carried out to examine the proposed method. Acceleration time history data measured at a bogie were re-sampled to every 0.25m track irregularity. In the simulation study, two sets of measured data were simulated. The second data set was obtained by a train with 10% more mass than the one for the first data set. The first set of simulated data was used to train the series-parallel mode of NARX neural network. Then, the track irregularities at the second time period are identified by using the measured acceleration data. The closeness of the identified track irregularity to the actual one is evaluated by PSD and RMSE.

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A Parametric Study on the Serviceability of Concrete Slab Track on Railway Bridges (철도교 콘크리트 슬래브궤도의 사용성에 관한 매개변수 영향 연구)

  • Park, Hong-Kee;Jang, Seung-Yup;Yang, Sin-Chu;Park, Yong-Gul
    • Journal of the Korean Society for Railway
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    • v.12 no.1
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    • pp.95-103
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    • 2009
  • Deformations of bridge deck ends on abutments and piers bring about severe problems in track geometry and require maintenance work. In case of concrete slab track, more severe deformation and additional forces on rail and rail supports can be induced by bridge deck deformation, which affect the serviceability of track structure since concrete slab track is much stiffer than ballasted track and the behavior of track structure is integrated with that of bridge deck. In this study, the design variables affecting the serviceability of track structure are selected and the influence level is estimated by a parametric study. As a result, it is found that continuous span is advantageous than simply supported span and the stiffness of bridge bearing and rail fastener as well as the distance between last rail support and bridge bearing are most important parameters.

The criteria for the change ratio of track stiffness along transition area (접속구간 궤도강성변화 기준에 관한 연구)

  • Yang, Sin-Chu;Moon, Jae-Woo;Yu, Jin-Young
    • Proceedings of the KSR Conference
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    • 2007.05a
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    • pp.351-357
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    • 2007
  • The transition zone between railway embankment and structures, or different track types is known to be an area in which problems often arise and where extra care needs to be taken with maintenance. Differences in track stiffness have dynamic effects and these increase the force in the track and the extent of deformation. In this study, the criteria for the change ratio of track stiffness along transition area, and proper transition length are presented through train/track interaction analyses. Those are derived on the basis of permissible limitations of train and track performances such as rail stress, uplift force of fastener, reduction of dynamic wheel force, and acceleration of car body. A feasible method of evaluation of track stiffness which is necessary when a designer reviews whether the criteria are satisfied or not is also presented.

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Study on Torsion due to Automotive Body Type at Track Driving (궤적주행 시 차체 종류에 따른 비틀림에 관한 연구)

  • Choi, Youn-Jong;Lee, Joon-Seong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.1
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    • pp.57-62
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    • 2013
  • Because there is no suspension and differential devices at cart body, the deformation of the frame happened during kart driving affects the driving performance caused by the elastic deformation and the fatigue life of kart frame resulted from the permanent deformation. The dynamic behavior of kart caused by the torsional deformation during circular driving is the important factor of these two kinds of deformations. In order to analyze the dynamic behavior of kart at this curved section, GPS is used to trace the track of kart and the torsional stress at kart-frame has been measured with real time. The mechanical properties of kart-frames for leisure and racing are investigated through material property analysis and tensile test. Torsional stress concentration and frame distortion are investigated through stress analysis on frame on the basis of study result. The real karts for leisure and racing kart are also tested in each driving condition by using the driving analysis equipment. The driving behavior of kart at the curved section are investigated through this test. As the phenomenon of load movement due to centrifugal force at car is happened during circular driving, the torsional stress occurs at cart steel frame.

Characteristics of Track and Train Behaviors on High-Speed Railway Bridge/Earthwork Transiton Zone (고속철도 교량/토공 접속부에서의 궤도 및 차량 거동 특성)

  • Lee, Il-Wha;Kang, Yun-Suk;Kim, Eun;Son, Ki-Jun;Park, Chan-Kyoung
    • Proceedings of the KSR Conference
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    • 2003.10b
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    • pp.129-134
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    • 2003
  • It is very important to pay careful attention to construction of bridge/earthwork transition zone for high-speed railway. The transition zone of the railway is the section which roadbed stiffness is suddenly varied. Differences in stiffness have dynamic effects and these increase the forces in the track and the extent of deformation. An abrupt change of stiffness across two adjacent track portions cause irregular settlement of roadbed, track irregularity, lack of girder bending moment and reduction of lateral resistance. Especially on high-speed railway, track irregularity of transition zone cause sincere effect to track stability and train safety. And so continuous maintenance is needed. To verify this effect and to improve transiton zone capacity, In situ test, track irregularity and train acceleration test were performed on high-speed railway bridge/earthwork Transiton Zone.

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Research on the railroad reinforcement subgrade with short reinforcement and rigid facing (강성벽체와 단보강재를 갖는 철도보강노반에 대한 연구)

  • Kim, Dang-Sang;Kim, Ki-Hwan
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.09a
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    • pp.350-358
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    • 2009
  • To enhance the application of the reinforced retaining walls in the railway industry, this paper suggested a type of reinforcement subgrade with short reinforcement and rigid facing. To become popular the reinforced retaining walls in the industry, the deformation of retaining walls should be controlled below some limited level. In this paper, small scale and full scale tests of the proposed retaining walls were performed and their deformation characteristics were evaluated. Even though it has short reinforcement, the rigid type retaining wall had small deformation to the external train loading than the segmental type retaining wall had.

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Analysis of the Behavior of Concrete Track on Earthwork Considering the Increase in Train Speed (열차속도 증가를 고려한 토공상 콘크리트궤도의 거동 분석)

  • Kim, Jeong-Il;Ahn, Suk-Jun;Kwon, Jong-Wook;Kim, Jin-Il
    • Proceedings of the KSR Conference
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    • 2011.10a
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    • pp.3214-3219
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    • 2011
  • HONAM High Speed Railway project is under construction with the target to have 350km/h design speed from Songjeong Gwangju City to Osong. The track for the whole section of the line is scheduled to be a concrete track in order to decrease total life cycle cost (LCC) according to the decrease of track destruction. However, the study on the related parts to increase the train speed up to 400km/h is on going in order to strength the competitiveness of high speed railway. On this study, the stress of track has been analyzed according to the concrete track design method of Eisenmann using equivalent depth theory proposed by Odemark for behavior analysis of concrete track on track bed, which is having embankment deformation characteristics by train load. The behavior analysis of track is performed to analyze the stress of track bed layer and track according to the variation of design load and train speed. And also, the characteristics of concrete track have been figured out by analyzing the parameter according to the thickness of track bed layer.

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