• Title, Summary, Keyword: Ballasted track

Search Result 90, Processing Time 0.035 seconds

Parametric analysis on Deformation of Sharp Curved Ballasted Track (급곡선 자갈궤도의 궤도변형에 관한 매개변수 해석)

  • Choi, Jung-Youl;Kim, Jun-Hyung;Son, Gab-Soo;Kim, Sang-Jin
    • Journal of the Korean Society of Safety
    • /
    • v.32 no.4
    • /
    • pp.28-33
    • /
    • 2017
  • A sharp curved ballasted track on earthwork that was connected with a direct fixation slab track on steel box railway bridges have been deformed and damaged despite the frequently maintenance by a restoring force of sharp curved rail and track-bridge interaction forces such as axial forces and longitudinal displacement of continuous welded rail(CWR) owing to their structural characteristics, calling for alternatives to improve the structural safety and track irregularity. In this study, the authors aim to prove a cause of deformation for the sharp curved ballasted tracks to enhance the structural safety and track irregularity of ballasted track in service. A track-bridge interaction analysis and a finite-element method analysis for the sharp curved ballasted track were performed to consider the axial force and longitudinal displacement of CWR, the temperature and the effect of restoring force of sharp curved rail. From the results, the deformation of the sharp curved ballasted track with adjusted sleeper spacing from 833mm to 590mm were significantly reduced.

Experimental Study on Condition Evaluation for Railway Ballasted Track (자갈궤도의 상태평가를 위한 실험적 연구)

  • Choi, Jung-Youl;Bahng, Eun Young
    • Journal of the Korean Society of Safety
    • /
    • v.33 no.2
    • /
    • pp.152-157
    • /
    • 2018
  • The degradation and damage of the components for ballasted track could be caused a serious problem for railway safety. Therefore, the integrity evaluation of ballasted track condition is important to ensure and predict that the track safety and track maintenance. Various track components such as rail pad, ballast, sleeper, and rail that are widely used in Republic of Korea and represent a range of physical properties have been selected for this research. In this study, the experimental modal analysis was performed by the non-destructive testing. Modal test results were obtained from the field test and used to assess the condition of the track components. From the field test, the system of ballasted track was found to be simplified as a two-degree-of-freedom(2DOF) dynamic system. The condition of track component was found to directly affect the dynamic response of ballasted tracks. As the results, the dynamic properties of the track component was depend on the track condition and was distributed more roughly and over a wider range than its initial design values. Further, the methodology presented in this study is possible to determine experimentally the fundamental track parameters which are required in the numerical analysis, and also are useful for the safety assessment of track condition.

A Comparison of Behavior of the Roadbeds of Ballasted & Concrete Track with the Cyclic Loading (자갈궤도와 콘크리트궤도에서의 하중재하에 따른 노반거동 비교)

  • Choi, Chan-Yong;Lee, Sung-Heok;Eum, Ki-Young
    • Journal of the Korean Geosynthetics Society
    • /
    • v.9 no.3
    • /
    • pp.1-8
    • /
    • 2010
  • The track systems installed in Korea railway consist of two types on ballasted track or ballastless track. In this study, it was compared with difference of the behaviors at roadbed with cyclic loading through full scale model test. From the results of model tests, loading distribution ratio of the concrete slab track become more widely distributed than ballasted track, and loading distribution ratio at concrete track was about 30:20:15. The concrete slab track is likely to behavior of the rigid plate, while ballasted track is such as flexible pavement. The vertical stresses of upper roadbed with traffic cyclic loading in concrete track were measured about 30 kPa or less. It was a scene very similar to the results of the field train running test. The vertical stress at concrete track was occurred approximately 4 times smaller than ballasted track. Also, the soil velocities with cyclic loading at the slab track were occurred about 0.3 cm/sec or less, its 8 times smaller than ballasted track.

  • PDF

Behavior Characteristics of Ballasted Track on Asphalt Roadbed Using Real Scale Test (실대형 실험을 통한 아스팔트 노반상 자갈궤도의 거동 특성)

  • Lee, Seonghyeok;Lee, Jinwook;Lee, Hyunmin
    • Journal of the Korean Society for Railway
    • /
    • v.18 no.3
    • /
    • pp.252-260
    • /
    • 2015
  • Ballasted track on an asphalt roadbed can be beneficial for its various effects such as (i) decreasing of roadbed thickness by dispersing train load; (ii) prevention of both strength reduction and weakening in roadbed system by preventing rainwater penetration; and (iii) reducing maintenance cost by preventing roadbed mud-pumping and frostbite. With these beneficial effects, ballasted track on asphalt roadbed has been widely used in Europe and Japan, and relevant research for applying such ballasted track on asphalt roadbed systems in Korea is ongoing. In this study, full-scale static and dynamic train load tests were performed to compare the performance of ballasted track on asphalt roadbed and ballasted track. The optimum thickness levels of asphalt and reinforced roadbeds, corresponding to the design criteria for reinforced roadbed of high-speed railway, was estimated using the FEM program ABAQUS. Test results show that the earth pressure on reinforced roadbed of ballasted track on the asphalt roadbed was relatively low compared with that of simple ballasted track. The elastic and plastic displacements of simple ballasted track on the asphalt roadbed were also lower than those of ballasted track. These test results may indicate that the use of ballasted track on asphalt roadbed is an advantageous system in view of long-term maintenance.

Vibration Characteristics of High-speed Railway Lines on the Type of Track (고속철도 궤도 타입에 따른 진동 특성)

  • Lee, Chan-Woo;Ham, Ham-Young;Kim, Jae-Chul
    • Proceedings of the KSR Conference
    • /
    • /
    • pp.332-336
    • /
    • 2011
  • IN THIS STUDY, BASED ON THE TYPE OF HIGH SPEED RAILWAY TRACK VIBRATION CHARACTERISTICS WERE MEASURED AT KTX VEHICLE. KTX ROUTE BALLASTED TRACK HAS BEEN INSTALLED TOGETHER WITH THE CONCRETE TRACK. CONCRETE MUST BE TRACK IRREGULARITY THAN BALLASTED TRACK, VEHICLES VIBRATION VALUES THAT ARE SMALLER. ALSO, IN TERMS OF MAINTENANCE, CONCRETE TRACK IS KNOWN TO BE MORE FAVORABLE THAN THE BALLASTED TRACK. PHASE 2 IS THE KTX, DAEGU - BUSAN IS A SECTION OF CONCRETE TRACK. IN THIS STUDY, "KUUNG-BU HIGH-SPEED RAILWAY LINES" INSTALLED ON THE CONCRETE TRACK AND BALLASTED TRACK KTX FROM THE VEHICLE WHEN INSTALLED BETWEEN RAILS, SLEEPER AND BALLAST ON THE TRACK WAS MEASURED VIBRATIONS.

  • PDF

Parametric Study on Geogrid-Reinforced Track Substructure

  • Oh, Jeongho
    • International Journal of Railway
    • /
    • v.6 no.2
    • /
    • pp.59-63
    • /
    • 2013
  • The purpose of this paper was to evaluate the effectiveness of geogrid for conventional ballasted track and asphalt concrete underlayment track using PLAXIS finite element program. Geogrid element was modeled at various locations that include subballast/subgrade, subballast/ballast interfaces, middle of the ballast, and one-third depth of the ballast. The results revealed that the effectiveness of geogrid reinforcement appeared to be larger for ballasted track structure compared to asphalt concrete underlayment track. Particularly, in case of installing geogrid at one-third depth of ballast layer in a conventional ballasted track, the most effectiveness of geogrid reinforcement was achieved. The influence of geogrid axial stiffness on track substructure response was not clear to conclude. Further validations using a discrete element method along with experimental investigation are considered as a future study. The effect of asphalt concrete layer modulus was evaluated. The results exhibited that higher layer modulus seems to be effective in controlling displacement and strain of track substructure. However it also yields slightly higher stresses within track substructure. It infers that further validations are required to come up with optimum asphalt concrete mixture design to meet economical and functional criteria.

A Study on Effect of Vibration Reduction with Ballast Mat of Ballasted Track in Tunnel (터널내 자갈도상제도의 자갈도상매트 시공 후 진동 저감 효과에 대한 연구)

  • You, Chung-Jun
    • Journal of the Korean Society for Railway
    • /
    • v.12 no.1
    • /
    • pp.167-174
    • /
    • 2009
  • Due to the travelling of the train with high speed the period of maintenance activities of the ballasted track is coming to be short, and more from the residential area of the ballasted track tunnel circumference the civil appeal is increasing with railroad vibration problem. To reduce the vibration problem and a maintenance cost establishes the ballast mat in the tunnel within part segment. In this study, to estimate the vibration reduction effect of the ballast mat we have done a comparative analysis with the vibration field test by the transit train by at the ballasted track with ballast mat and the standard ballasted track without vibration protection in tunnel.

An Experimental Study on the Spring Stiffness Test Method of under Sleeper Pad for Ballasted Track (자갈궤도용 침목방진패드의 수직 스프링강성 시험기법에 관한 실험적 연구)

  • Choi, Jung-Youl;Shin, Tae-Hyoung
    • Journal of the Korean Society of Safety
    • /
    • v.31 no.3
    • /
    • pp.82-88
    • /
    • 2016
  • Ballasted gravel will be damaged or worn by the repetitive train load. And these damages of ballast gravel could be increased by increasing vehicle speed. Therefore, various techniques for reducing the ballast pressure have been proposed, such as the attached pad type of sleeper bottom for ballasted track. In this study, spring stiffness test method were proposed to evaluate the performance of under sleeper pad for ballasted track. Standard ballast plate(SBP) was developed to simulate the ballast gravel and compared with the foreign test results. Experimental results showed a trend similar to the previous studies according to various loading plate type. specimen type(Type A, Type B) differences in spring stiffness according to hardness were not significant. Also, the FSP (Flat steel plate) - shaped jig is about 80% of the spring stiffness was greater than SBP. Therefore, to evaluate the actual spring stiffness of under sleeper pad for ballasted track, it was important to adopted the appropriate spring stiffness test method using the SBP to simulate actual field conditions.

A comparison between the dynamic and static stiffness of ballasted track: A field study

  • Mosayeb, Seyed-Ali;Zakeri, Jabbar-Ali;Esmaeili, Morteza
    • Geomechanics and Engineering
    • /
    • v.11 no.6
    • /
    • pp.757-769
    • /
    • 2016
  • Rail support modulus is an important parameter for analysis and design of ballasted railway tracks. One of the challenges in track stiffness assessment is its dynamic nature under the moving trains which differs it from the case of standing trains. So the present study is allocated to establish a relation between the dynamic and static stiffness of ballasted tracks via field measurements. In this regard, two different sites of ballasted tracks with wooden and concrete sleepers were selected and the static and dynamic stiffness were measured based on Talbot - Wasiutynski method. In this matter, the selected tracks were loaded by two heavy and light car bodies for standing and moving conditions and consequently the deflection basins were evaluated in both sites. Knowing the deflection basins respect to light and heavy loading conditions, both of static and dynamic stiffness values were extracted. Finally two definite relations were obtained for ballasted tracks with wooded and concrete sleepers.

Evaluation of Rail pad Stiffness Considering Stress of Rail (레일응력을 고려한 레일패드강성 결정)

  • Park, Dae-Geun;Kim, Jae-Hak;Son, Gi-Jun;Kim, Han-Jong
    • Proceedings of the KSR Conference
    • /
    • /
    • pp.419-431
    • /
    • 2007
  • The track and rail surface geometry is of prime importance on the requirement for track dynamic stiffness, particularly for the speed of 350 km/h, for which both the requirement for fatigue and tensile strength limits require a lower stiffness than 100 kN/mm, which is near the value for ballasted track. However, the track quality has been considered as being the same for 350 km/h as that for 300 km/h, and based on ballasted track, and the track geometry may be kept in better condition with a slab track(probably more similar to the medium quality track geometry of ballasted track). In conclusion, under the condition that the track geometry quality provided by the concrete slab system is fairly good, and that the required maintenance is applied to the rail surface, there would be no safety risk if the fastening system point stiffness reaches 160 kN/mm for 300 km/h operation, and 110 N/mm at 350 km/h.

  • PDF