• Title, Summary, Keyword: 노반거동

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Roadbed Behavior in Managanese Crossing of Turnout System (분기기 망간 크로싱부 노반거동)

  • Jeon, Sang-Soo;Eum, Ki-Young;Kim, Jae-Min
    • Journal of the Korean Geotechnical Society
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    • v.24 no.2
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    • pp.45-57
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    • 2008
  • The improved turnout system is developed to speed-up the pre-existing railroad. The research has been actively carried out far the improved turnout system and the impact factor is estimated using the data sets achieved from the dynamic wheel-load field tests in both the conventional and the improved turnout system. In this study, the track performance and roadbed behavior are examined for the conventional and improved turnout system using the estimated impact factor. Dynamic wheel load and rail pressure are evaluated to assess the track performance. Roadbed stress and settlements are estimated using numerical analysis. Additionally, the stability of roadbed is estimated in soft roadbed condition influenced by the weather effects and cyclic train loading. The results show that dynamic wheel load, rail pressure, roadbed stress, and roadbed settlements in the improved turnout system substantially decrease compared with those in the conventional turnout system.

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.

Evaluation of the Roadbed Behavior During Tilting-train Operation in Curved Track Using Numerical Analysis (틸팅차량의 곡선부 운행시 수치해석을 이용한 노반거동 평가)

  • Jeon, Sang-Soo;Eum, Gi-Young;Kim, Jae-Min
    • Journal of the Korean Geotechnical Society
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    • v.23 no.6
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    • pp.115-126
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    • 2007
  • The tilting-train is very attractive to the railroad users in the world because it runs with high speed in curved track using pre-existing infrastructure. The tilting-train has a unique allowable speed and mechanism expecially in curved track. Therefore, it should be evaluated in terms of the stability of the train operation and roadbed. In this study, when the tilting-train is being operated with the allowable speed, the behavior of the roadbed is evaluated by examining the settlement and bearing capacity of the roadbed. Additionally, the stability of the roadbed is estimated in the condition of soft roadbed influenced by the weather effects and cyclic train loading. The numerical results show that the roadbed settlements satisfy the allowable settlement when Young's moduli of the upper roadbed and in-situ soil are more than $2,300t/m^2\;and\;3,300t/m^2$, respectively, in the continuous welded rail (CWR) and $3,800t/m^2\;and\;4,600t/m^2$, respectively, in the rail joint.

Laboratory Test for Permanent Settlement Behavior of Geo-materials used in Railway Considering Grain size distribution and Water content (입도 및 함수비 조건에 따른 철도 노반 재료의 영구침하거동 요소시험평가)

  • Lee, Sung Jin;Lee, Il Wha;Lee, Su Hyung;Eum, Ki Young
    • Journal of the Korean Society for Railway
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    • v.18 no.4
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    • pp.354-362
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    • 2015
  • Since allowable settlement of concrete slab track is about 30mm, a lot of attention must be paid to the settlement of the earthwork (reinforced trackbed, upper subgrade, under subgrade) under the concrete track. To this end, more experimental data should be accumulated through tests for these materials. In this study, we evaluate the long-term settlement of reinforced trackbed and subgrade materials using factors such as repeated loading conditions, water content, and grain size distributions in a large triaxial test and a large oedometer test. In cases in which the performance of the reinforced trackbed layer meets the design criteria, the settlement caused by train load was considerably small. But, when the water content increases in the subgrade, unexpectedly large settlement might occur for certain grain size distributions of the subgrade materials.

Resilient Moduli of Sub-ballast and Subgrade Materials (강화노반 및 궤도하부노반 재료의 회복탄성계수)

  • Park, Chul-Soo;Choi, Chan-Yong;Choi, Choong-Lak;Mok, Young-Jin
    • Journal of the Korean Society for Railway
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    • v.11 no.1
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    • pp.54-60
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    • 2008
  • In the trackbed design using elastic multilayer model, the stress-dependent resilient modulus $(E_R)$ is an important input parameter, that is, reflects substructure performance under repeated traffic loading. However, the evaluation method for resilient modulus using repeated loading triaxial test is not fully developed for practical purpose, because of costly equipment and the significantly fluctuated values depending on the testing equipment and laboratory personnel. The this study, the paper will present an indirect method to estimate the resilient modulus using dynamic properties. The resilient modulus of crushed stone, which is the typical material of sub-ballast, was calculated with the measured dynamic properties and the range of stress level of the sub-ballast, and approximated with the power model combined with bulk and deviatoric stresses. The resilient modulus of coarse grained material decreases with increasing deviatoric stress at a confining pressure, and increases with increasing bulk stress. Sandy soil (SM classified from Unified Soil Classification System) of subgrade was also evaluated and best fitted with the power model of deviatoric stress only.

Estimation of the Roadbed Settlement and Bearing Capacity According to Radius of Curve and Cant in Railroad (철도의 곡선반경 및 캔트에 따른 노반의 침하 및 지지력 산정)

  • Jeon, Sang-Soo;Eum, Gi-Young;Kim, Jae-Min
    • Journal of the Korean Society of Hazard Mitigation
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    • v.7 no.1
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    • pp.29-38
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    • 2007
  • The research on the track performance and stability of the tilting-train was performed and the settlement of the roadbed was estimated as the tilting train was being operated on the rail joint under the allowable velocity subjected to the track performance and the stability of the tilting-train. Since the impact on the continuous welded rail (CWR) induced by the tilting-train loading is different from the impact on the rail joint, it needs to investigate the settlement of the roadbed beneath the CWR. In this study, when the tilting-train is being operated on the CWR under the allowable velocity subjected to the track performance and the stability of the tilting-train, the settlement and bearing capacity of the roadbed beneath the CWR have been evaluated using numerical analysis and compared with those beneath the rail joint. The numerical results show that the settlements of the roadbed beneath CWR and rail joint are amount to 71.2% and 88.8% of the allowable settlement, respectively. And the stresses are amount to 10.4% and 12.1% of the allowable bearing capacity, respectively.

Tilting Train-induced Roadbed Response on the Conventional Line (틸팅열차 주행시 기존선 흙 노반의 응답특성)

  • Koh, Tae-Hoon;Kwak, Yeon-Suk;Hwang, Seon-Keun;SaGong, Myung
    • Journal of the Korean Society for Railway
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    • v.14 no.5
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    • pp.433-441
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    • 2011
  • It is a fact that the straightening of track alignment is one of the undoubted ways to improve the train speed on conventional lines, while that requires huge investment resources. Therefore, the operation of a tilting train as well as the minimum improvement of track is suggested as an effective and economical alternative way for the speed-up of conventional lines. Since a driving mechanism of tilting train is different from those of existing trains, in order to make sure its operation safety and stability on conventional line, the performance of track and roadbed must be preferentially evaluated on the conventional line. Furthermore, it is necessary to estimate the tilting-train-induced roadbed response in detail since the roadbed settlement can lead to the track deformation and even derailment. In this research, the patterns of wheel load and lateral force were monitored and analyzed through the field tests, and the derailment coefficient and degree of wheel off-loading were calculated in order to evaluate the tilting train running safety depending on the running speeds (120km~180km) on the conventional line. Moreover, roadbed pressure, settlement and acceleration were also observed as tilting-train-induced roadbed responses in order to estimate the roadbed stability depending on the running speeds. Consequently, the measured derailment coefficient and degree of wheel off-loading were satisfied with their own required limits, and all of the roadbed responses were less than those of existing high-speed train (KTX) over an entire running speed range considered in this study. As a result of this study, the tilting train which will be operated in combination with existing trains is expected to give no adverse impact on the conventional line even with its improved running speed.

Optimal Section of Ballasted Asphalt Track Considering Design Lifetime and Economic Feasibility (설계수명 및 경제성을 고려한 유도상 아스팔트 궤도의 최적 단면 산정)

  • Lee, Seonghyeok;Lee, Jinwook;Lee, Hyunmin
    • Journal of the Korean Society for Railway
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    • v.18 no.3
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    • pp.241-251
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    • 2015
  • Compared with ballasted track (BT), ballasted asphalt track (BAT) has been increasingly adopted in many countries due to its more greatly reduced reinforced roadbed thickness and smaller cumulative plastic deformation, and its advantages in terms of maintenance. In this respect, the authors' previous research includes analysis of BAT sections that show performance similar to that of BT sections of the present specifications; reliability verification of the analysis results through real-sized static and dynamic train-load tests were performed. Based on previous research, this paper estimates the track lifetime using the strain of the lower roadbed according to reinforced roadbed thickness; using probabilistic LCC analysis, this paper presents a BAT section that satisfies the design lifetime and that has performance similar to or higher than that of BT.

A Basic Study on the Geobag System for Urgent Restoration of the Collapsed Roadbed (강우로 유실된 철도노반 긴급복구를 위한 지오백시스템 개발 기초연구)

  • 조삼덕;황선근;이대영;이광우
    • Journal of the Korean Geotechnical Society
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    • v.19 no.2
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    • pp.255-265
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    • 2003
  • A series of laboratory tests were performed to evaluate engineering properties of geobag system which is used for urgent restoration of the collapsed roadbed. In this study, the suitable geobag size was proposed as 44cm wide and 66cm long, and the suitable filling ratio of geobag was also proposed as 80% through the static loading tests. Also a series of model tests were carried out to investigate the characteristics of the engineering behavior and the distribution of earth pressure of the geobag roadbed under static and dynamic loading.