• Title, Summary, Keyword: Asphalt concrete track

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Parametric Study on Geogrid-Reinforced Track Substructure

  • Oh, Jeongho
    • International Journal of Railway
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    • v.6 no.2
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    • pp.59-63
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    • 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.

Design Graphs for Asphalt Concrete Track with Wide Sleepers Using Performance Parameters (성능요소를 반영한 광폭 침목형 아스팔트콘크리트 궤도 설계그래프)

  • Lee, SeongHyeok;Lim, Yujin;Song, Geunwoo;Cho, Hojin
    • Journal of the Korean Society for Railway
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    • v.19 no.3
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    • pp.331-340
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    • 2016
  • Wheel load, design velocity, traffic amount (MGT), stiffness and thickness of sub-layers of asphalt concrete track are selected as performance design parameters in this study. A pseudo-static wheel load computed considering the dynamic amplification factor (DAF) based on the design velocity of the KTX was applied to the top of asphalt concrete track for full three dimensional structural analysis using the ABAQUS program. Tensile strains at the bottom of the asphalt concrete layer and vertical strains at the top of the subgrade were computed from the structural FEA with different combinations of performance parameter values for one asphalt concrete track section. Utilizing the computed structural analysis results such as the tensile strains and the vertical strains, it was possible to develop design graphs to investigate proper track sections for different combination of the performance parameters including wheel load, design velocity, traffic amount(MGT), stiffness and thickness of asphalt concrete layers for any given design life. By analyzing the proposed design graphs for asphalt concrete track, it was possible to propose simple design tables that can be used by engineers for the effective and fast design of track.

Development of Device to Resist Horizontal Displacement of Asphalt Concrete Track (아스팔트콘크리트 궤도용 궤도변위 저항 장치 개발)

  • Lee, Seonghyeok;Yoon, Wooyong;Bae, Younghoon
    • Journal of the Korean Society for Railway
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    • v.19 no.6
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    • pp.744-754
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    • 2016
  • Asphalt concrete track (ACT) is a track system connecting wide sleepers and concrete panels on top of an asphalt concrete layer; such a system requires adequate resistance force against various longitudinal and lateral external loads. In this study, a series of experiments were carried out to assess the longitudinal and lateral resistance force of a wide sleeper and concrete panel type ACT. The required shear resistance force of the horizontal displacement restraint device (HDRD) was evaluated. Furthermore, a concrete block type anchor and a steel pipe type anchor were developed as HDRDs. The shear resistance force was decided based on the experimental results of horizontal shear tests for each anchor system. In addition, proper numbers and arrangement design guidelines for the HDRDs were suggested considering the shear resisting capacity and economics for HDRDs applied to ACT.

Dynamic Analysis of Asphalt Concrete Pavement Structure

  • 윤경구;박제선
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.241-246
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    • 1996
  • A new solution for the dynamic analysis of as asphalt concrete pavements under moving loads has been developed. The asphalt concrete pavement can be modeled in elastic or viscoelastic medium of multi-layered structure. The subgrade can be modeled as either a rigid base or a semi-infinite halfspace. The loads may be constant or arbitrary circular loads into one direction. The method utilizes the Complex Response Method of transient analysis with a continuum solution in the horizontal direction and a finite-element solution in the vertical direction. This proposed method incorporates such important factors as wave propagation, inertia and damping effects of the medium as well as frequency-dependent asphalt concrete properties. The proposed method has been validted with the full-scale field truck test, which was conducted on instrumented asphalt concrete section on a test track at PACCAR Technical Center in Mount Vernon, Washington. Comparison with field strain data from full-scale pavement tests has shown excellent agreement. Theoretical results have shown that the effect of vehicle speed is significant and that it is in part due to the frequency-dependent

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Development of Wide Prestressed Concrete Sleeper for Asphalt Concrete Track (아스팔트 콘크리트 궤도용 광폭 PSC침목 개발)

  • Bae, Young-Hoon;Lee, Seong-Hyeok;Kim, Eung-Rok
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.2
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    • pp.34-42
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    • 2018
  • In order to minimize the deformation of asphalt concrete track(ACT) and ensure the structural safety, a wide type concrete sleeper is necessary to distribute vehicle loading and reduce the exposure of the asphalt roadbed. In this research, the wide prestressed concrete(PSC) sleeper for ACT was developed through the shape design and the structural safety was reviewed using finite element analysis. Furthermore, static test, dynamic test and fatigue test were carried out according to EN13230-2 to verify the design appropriateness of the wide PSC sleepers for ACT. The performance test showed that the developed wide PSC sleeper for ACT meets all the performance requirements by European standard.

Application of the Absorbing Boundary Condition in Moving Force Analysis of Asphalt Concrete Track (흡수경계조건의 아스팔트 콘크리트 궤도 동적 해석에의 적용)

  • Lee, Seonghyeok;Chung, Keunyoung;Jung, Wooyoung
    • Journal of the Korean Society for Railway
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    • v.19 no.1
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    • pp.54-66
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    • 2016
  • In this study, the absorbing boundary condition was adopted to prevent elastic wave propagation due to abrupt load condition changes in moving force analysis. It was proven to be effective in reducing inappropriate noise components. Furthermore, to verify whether fixed point excitation in a laboratory test can simulate train movement effectively, the results of dynamic analysis for fixed point excitation and moving force conditions were analyzed. The dynamic stability of an asphalt track structure under a KTX train condition was also studied. Additionally, the dynamic safety of asphalt tracks was verified by comparing the results of a moving force analysis under a KTX train load and a quasi-static analysis under the design standard Korean train load.

A Study on Behavior of Concrete Slab Track subjected to High Speed Train Loads (고속열차하중을 받는 슬래브궤도의 동적거동에 관한 연구)

  • 조병완;김영진;허민회;정태호
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.493-598
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    • 2000
  • In the rail facilities, the rail track consists of rail, tie, fastening, accessories and bed. The rail track is largely divided into Ballast Bed Track (BBT) and Concrete Bed Track (CBT) according to the type of bed. In this thesis, among Concrete Bed Track, slab track, which is used for the Japanese high speed railway, is a target of this study. Dynamic analysis by using finite element method are performed where moving train load is periodic function. Then through parametric study, some conclusions are obtained as follows. Cement Asphalt Mortar (CAM) affects contrary mechanical behavior to rail and slab greatly. Therefore, change of CAM spring coefficient should be handled with care. For slab thickness, thin slab is more profitable to reduction of vibration of rail than thick one but mechanical capacity of slab is deteriorated. Improved structural type is proposed, then structural analysis is performed for this one. This type is effective to reduction of vibration of railway system.

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Development of Prefabricated Slab Panel for Asphalt Concrete Track (아스팔트 콘크리트 궤도용 사전제작형 슬래브 패널 개발)

  • Baek, In-Hyuk;Lee, Seong-Hyeok;Shin, Eung-Soo
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.23 no.3
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    • pp.75-82
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    • 2019
  • Slab panels are very important to develop asphalt concrete (AC) track for minimizing the roadbed stress due to the train load and reducing the plastic deformation of infrared-sensitive AC. In this study, the slab panel for AC track was developed through the shape design and the indoor performance test and its structural integrity has been investigated through the finite element analysis under the flexural tensile stress and the design moment according to various static load combination by KRL-2012 standard train load model and KR-C code. In order to verify the suitability of the slab panel for AC track, static bending strength test and dynamic bending strength test were performed according to EN 13230-2. Results show that the slab panel for AC track satisfies all the performance standards required by European standards such as crack loads and crack extension.

A Study on Behavior of Concrete Slab Track subjected to High Speed Train Loads (고속열차하중을 받는 슬래브궤도의 동적거동에 관한 연구)

  • 조병완
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.485-492
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    • 2000
  • In the rail facilities the rail track consists of rail tie fastening accessories and bed,. The rail track is largely divided into Ballast Bed Track(BBT) and Concrete Bed Track(CBT) according to the type of bed. In this thesis among Concrete Bed Track slab track which is used for the Japanese high speed railway is a target of this study. Dynamic analysis by using finite element method are performed. where moving rain load is periodic function. Then through parametric study some conclusions are obtained as follow. Cement Asphalt Mortar(CAM) affects contrary mechanical behavior to rail and slab greatly. Therefore change of CAM spring coefficient should be handled with care, For slab thickness thin slab is more profitable to reduction of vibration of rail than thick one but mechanical capacity of slab is deteriorated, Improved structural type is proposed then structural analysis is performed for this one. This type is effective to reduction of vibration of railway system.

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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.