• Title, Summary, Keyword: 콘크리트궤도

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Estimation of Bending Fatigue Life of CWR in Concrete Track (콘크리트궤도 장대레일의 휨 피로수명 평가)

  • Sung, Deok-Yong;Tae, Sung-Sik;Park, Kwang-Hwa;Kong, Sun-Yong;Park, Yong-Gul
    • Proceedings of the KSR Conference
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    • pp.64-71
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    • 2010
  • It is suggested that the service life of the continuous welded rail(CWR) is estimated by the relationship between the rail surface irregularity according to the accumulated passing tonnage and bending fatigue of welded part in CWR. In this study, based on the results of bending fatigue tests of rail and results of measuring tests in situ of rail bending stress, this study estimated the bending fatigue life of welded rail in concrete track, adopting a Haibach's rule. The bending fatigue life of CWR considered the rail surface irregularity, train speed and the S-N curve by types of rail welding. In addition, this study estimated it for the fracture probability 1%, 0.1%, 0.01%. Therefore, this study proposed bending fatigue life of CWR in concrete track.

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Deformation and Stress Distribution of Discontinuous Precast Concrete Track Slab : I. Initial and Temperature Deformation (불연속 프리캐스트 콘크리트궤도 슬래브의 변형과 응력 분포 : I. 초기 및 온도 변형)

  • 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.625-636
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    • 2017
  • This study looked into the behavior of precast concrete track due to temperature variation and initial track deformation and examined the effect of initial deformation and deformation caused by temperature gradient on the stress distribution of slab under train load. In this paper, one of two papers in a series, a finite element analysis model for calculating deformation and stress of precast concrete track was proposed; the temperature distribution and displacements measured at the precast concrete track in the field were compared with the analytical results. The results show that the slab always curled up due to initial deformation; by comparing the measured displacements with the displacements calculated by taking measured temperatures at each depth as input, the effective built-in temperature (EBITD), the temperature difference between the top and bottom of the slab corresponding to the initial deformation, can be estimated. If EBITD is relevantly assumed, the calculated displacements correlate well with the measured ones.

A Study on the Tensile Failure of a Notched Concrete (노치가 있는 콘크리트의 인장파괴 거동에 관한 연구)

  • 이준석;최일윤;엄주환;방춘석
    • Magazine of the Korea Concrete Institute
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    • v.9 no.5
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    • pp.189-196
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    • 1997
  • 본 연구에서는 유한요소법을 이용한 콘크리트 인장균열의 발생 및 전파양상을 모형화하기 위하여 분산균열(smeared crack) 모델의 일종인 2차원 균질화된 균열(homogenized crack)모형을 제안하였다. 제안한 모형은 인장균열면을 따라 속도 불연속계(velocity discontinuity)를 도입하고 평형방정식 빛 적합방정식을 이용하여 인장균열을 포함한 콘크리트의 구성방정식을 유도할 수 있으며 인장균열이 소성연화거동을 하는 경우. 유한요소망내에서 객관성이 유지될 수 있음을 밝히기 위하여 1차원 영역내에서 엄밀해를 유도하였다. 제안한 모형을 이용한 1차원 또는 2차원 유한요소 해석은 기존의 노치를 포함한 콘크리트 시편에 대한 실험과 상응하는 결과를 보였을 뿐만 아니라 유한요소망의 객관성이 유지되고 있음을 밝혔다. 제안한 모형은 큰 어려움없이 3차원 영역으로 확대할 수 있을 것이며 이에 대한 추가적인 연구가 계속될 것이다.

A Dynamic Behavior Evaluation of the Curved Rail according to Lateral Spring Stiffness of Track System (궤도시스템의 횡탄성에 따른 곡선부 레일의 동적거동평가)

  • Kim, Bag-Jin;Choi, Jung-Youl;Chun, Dae-Sung;Eom, Mac;Kang, Yun-Suk;Park, Yong-Gul
    • Proceedings of the KSR Conference
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    • pp.517-528
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    • 2007
  • Domestic or international existing researches regarding rail damage factors are focused on laying, vehicle conditions, driving speed and driving habits and overlook characteristics of track structure (elasticity, maintenance etc). Also in ballast track, as there is no special lateral spring stiffness of track also called as ballast lateral resistance in concrete track, generally, existing study shows concrete track has 2 time shorter life cycle for rail replacement than ballast track due to abrasion. As a result of domestic concrete track design and operation performance review, concrete track elasticity is lower than track elasticity of ballast track resulting higher damage on rail and tracks. Generally, concrete track has advantage in track elasticity adjustment than ballast track and in case of Europe, in concrete track design, it is recommended to have same or higher performance range of vertical elastic stiffness of ballast track but domestically or internationally review on lateral spring stiffness of track is very minimal. Therefore, through analysis of service line track on site measurement and analysis on performance of maintenance, in this research, dynamic characteristic behaviors of commonly used ballast and concrete track are studied to infer elasticity of service line track and experimentally prove effects of track lateral spring stiffness that influence curved rail damage as well as correlation between track elasticity by track system and rail damage to propose importance of appropriate elastic stiffness level for concrete and ballast track.

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Correlation Analysis Between Crack and TQI in RC Slab Track (철도콘크리트 슬래브 궤도상의 균열과 TQI 상관성 분석)

  • Kwon, Sae Kon;Park, Mi Yun;Kim, Doo Kie;Park, Jae Hak
    • Journal of Korean Society of Disaster and Security
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    • v.5 no.2
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    • pp.71-79
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    • 2012
  • Recently, in the total railroad construction field, the concrete slab track is adapted, not ballast track. Because the ballast track have the characteristics doing the ongoing maintenance and difficult to handle increasing maintenance costs, eventually the concrete slab track is selected as an alternative. However, owing to the hydration heat reactions and temperature affected shrinkage cracks related to concrete itself, a variety of studies to solve maintenance problems related to concrete slab track are underway. This study analysed characteristics of TQI values evaluating the track irregularity, searched the relationship between crack progress and TQI, and then evaluated of the correlation between the two values. Through this method, there is a need to complete the problems of the current method, only TQI is the main decision making tool in track maintenance, and also the need for the development of evaluation index considering the crack.

Analysis of Allowable Settlement on Tracks of High Speed Railway (고속철도 궤도 종류에 따른 허용침하량 분석)

  • Kim, Young-Ho;Jeong, Sang-Seom;Seol, Hoon-Il;Han, Young-Ah
    • Journal of the Korean Geotechnical Society
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    • v.24 no.11
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    • pp.25-34
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    • 2008
  • An application of concrete track is being actively processed for the construction of Korean high speed railway. The concrete track has an advantage in decreasing the maintenance cost, whereas it has much difficulty controlling the long term settlement after settlement occurred. Therefore, the management and control of settlement are very important for the successful construction of concrete track. The purpose of this paper is to verify the allowable settlement between concrete track and ballast track, and piled raft foundation installation effects as settlement reducers for concrete track. Therefore, a series of 3D finite element analyses that take into account the allowable settlement were performed for major parameters such as soil condition, pile installation and loading type. Based on the analysis, it is shown that concrete track causes much smaller settlement than ballast track, and the effect of installation is necessary to effectively reduce the settlement of concrete track.

Development of a Nondestructive Seismic Technique for Flexural Rigidity of Concrete Track as Slab Displacement Index (콘크리트 슬래브궤도의 휨강성 평가를 위한 비파괴 탄성파 기법의 개발)

  • Cho, Mi-Ra;Joh, Sung-Ho;Lee, Il-Wha
    • Journal of The Korean Society of Civil Engineers
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    • v.28 no.6D
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    • pp.905-913
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    • 2008
  • Recently, concrete tracks are introduced into high-speed railroads as an alternative to ballast tracks. Concrete tracks are superior to ballast tracks in the aspect of durability, maintenance and safety. However, deteriorated stiffness of railroad bed and settlement of soft ground induced by trapped or seepage water lead to problems in safety of train operation. In this research, flexural rigidity of concrete tracks was employed as an index of track displacement and a new seismic technique called FRACTAL (Flexural-Rigidity Assessment of Concrete Tracks by Antisymmetric Lamb Waves) method was proposed to delineate flexural rigidity of concrete tracks in a 2-D image. In this paper, to establish theoretical background, parametric research was performed using numerical simulations of stress-wave tests at concrete tracks. Feasibility of the FRACTAL technique was proved at a real concrete track for Korean high-speed trains. Validity of the FRACTAL technique was also verified by comparing the results of impulse-response tests performed at the same measurement array and the results of DC resistivity survey performed at a shoulder nearby the track.

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The Prediction Equation for Bending Stress of Rail in Concrete Track by the Linear Multiple Regression Analysis (중회귀분석을 통한 콘크리트궤도 레일 휨응력 예측식)

  • Sung, Deok-Yong;Lim, Hyoung-Jun;Lee, Dong-Wook;Kim, Bag-Jin;Park, Yong-Gul
    • Proceedings of the KSR Conference
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    • pp.315-323
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    • 2010
  • It is suggested that the service life of the continuous welded rail(CWR) is estimated by the relationship between the rail surface irregularity according to the accumulated passing tonnage and bending fatigue of welded part in CWR. In this study, it measured bending stress of rail according to the rail surface irregularity in the concrete track on the Seoul Metro. In addition, the relationship between rail surface irregularity and bending stress in concrete track is analyzed by results of the field test. Finally, this study clarified the relationship among bending stress(Y) of rail, train speed(U), rail surface irregularity(v, w) in concrete track. The result of this study is able to use the basis data to establishing the periodic replacements criterion of CWR.

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Study of the Long-Term Behavior Characteristics of Roadbed on Concrete Track of High-speed Railway (고속철도 콘크리트 궤도상 토공노반의 장기거동 특성 연구)

  • Choi, Chan-Yong;Jung, Jae-Hyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.4
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    • pp.8-16
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    • 2018
  • This study examined the long-term behavior of a roadbed using high-speed railway concrete track and roadbed measurement data and evaluated the long-term performance of the track and roadbed. Recently, high-speed railway track type has been adopted as a concrete slab. On the other hand, the concrete track is vulnerable to roadbed settlement. In the case of gravel tracks, it is easy to restore the original state by maintenance even if the roadbed settles. On the other hand, in the case of the concrete track, if excessive settlement of the roadbed occurs, cracks are generated continuously on the slabs and sleepers, resulting in greatly reduced usability. For this reason, it is difficult to restore the original state only by partial maintenance. In this paper, a long-term performance evaluation was carried out on a concrete track during operation by monitoring the measurement data of sensors buried from the beginning of construction for approximately 3 years after the high-speed railway opened. Performance evaluation methods include a performance evaluation of track/roadbed when the train passes, long-term track and roadbed performance evaluation, analysis of the track/roadbed effect on long-term settlement and analysis of the factors influencing long-term settlement. The trail response of KTX-Sancheon was greatest in the track/roadbed performance evaluation by train. The results of the long-term track and roadbed performance evaluation were measured within the standard values. The track and roadbed performance impact assessment with long-term settlement was strongly related to TCL settlement. The influences of the water content and groundwater level were verified by analyzing the external factors of long-term settlement. Through such a method, the stability of a track/roadbed can be secured.

The Fatigue Life Evaluation of Continuous Welded Rail on a Concrete Track in an Urban Railway (도시철도 콘크리트궤도 장대레일의 피로수명 평가)

  • Kong, Sung-Yong;Sung, Deok-Yong
    • Journal of the Korean Society for Railway
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    • v.17 no.3
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    • pp.193-200
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    • 2014
  • In this study, fatigue tests on existing continuous welded rail (CWR) on a concrete track were carried out. Based on the test results, a S-N curve expressing the remaining life of the CWR at a fracture probability of 50% was obtained using weighted probit analysis suitable for small-sample fatigue data sets. As rails had different histories in terms of accumulated passing tonnage, the test data were corrected to average out the accumulated passing tonnage. The remaining service life for the CWR on the concrete track in an urban railway was estimated using the prediction equation for the bending stress of rail developed in the past to estimate rail base bending stress and taking the surface irregularities into consideration. Estimating the remaining service life of the CWR in an urban railway showed that the rail replacement period could be extended over 200MGT. In addition, comparing the concrete track to the ballast track, the fatigue life of rail was analyzed as approximately 300MGT higher than. Therefore, the rail replacement criteria needs to distinguish between the ballast track and the concrete track, and not the criteria needs to be changed as a target for the maintenance, although it is necessary to remove longitudinal rail surface irregularities at welds by grinding.