• Title/Summary/Keyword: Roadbed thickness

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A Study on the Settlement Prediction of Reinforced Roadbeds (고속전철 강화노반의 침하예측에 관한 연구)

  • 황선근;신민호;이일화;조용권
    • Proceedings of the Korean Geotechical Society Conference
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    • 2000.03b
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    • pp.346-353
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    • 2000
  • The benefit of reinforced roadbeds, such as roadbed reinforced with slag and roadbed with crushed stone has been known among engineers. In this study, model soil box test is executed to determine optimum roadbed thickness. As a result, a empirical solution for the settlement of reinforced roadbeds was suggested. Furthermore, optimum thickness of reinforced roadbed could be determined based on the settlement characteristic of reinforced roadbed among the several variables.

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A Research on the Reinforced Roadbed Thickness of Concrete Slab Track on Embankment Section (콘크리트 슬래브 궤도 흙쌓기 구간의 강화노반 두께에 관한 연구)

  • Shin, Seung-Jin;Shin, Min-Ho;Park, Jong-Guan;Lee, Il-Wha
    • Proceedings of the KSR Conference
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    • 2007.11a
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    • pp.1242-1247
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    • 2007
  • An active application of concrete track is being expected for the future constructions of Korea railroad. For the successful construction and design in embankment section, the roadbed behavior should be reasonably estimated using the proper analysis method. In this research, behaviors of reinforced roadbed constructed with the determined stiffness and thickness at embankment section were estimated through various design parameters and numerical analysis. A three dimensional finite element method was employed to determine the proper reinforced roadbed thickness at embankment section. The displacement and vertical stress caused by train loading were estimated and compared with the field test results. The bearing characteristics of concrete track roadbed were presented. Moreover, the method to determine thickness of reinforced roadbed was proposed.

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Estimation of Reinforced Roadbed Thickness based on Experimental Equation (노반재료의 소성침하 예측식을 이용한 강화노반 두께 산정)

  • Shin, Eun-Chul;Yang, Hee-Saeng;Choi, Chan-Yong
    • Proceedings of the KSR Conference
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    • 2008.06a
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    • pp.1747-1755
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    • 2008
  • Design of the reinforced roadbed thickness is concerned with safe operation of trains at specified levels of speed, axle load and tonnage. There are two methods for evaluating it. One is using an experimental equation and the other is using elastic theory with considering axle load, material properties of subsoils and allowable elastic settlement. Multi-layered theory is used to determine reinforced roadbed thickness by RTRI. Although their reinforced roadbed thickness is designed with an objective of achieving a minimum standard 2.5mm of settlement on the subgrade surface, it is hardly applied to real design. Li(1994) has suggested the experimental model which design approach is to limit plastic strain and deformations for the design period. It is worth due to adopting soil equivalent number of repeated load application. Moreover, it has been a more advanced method than existing design methods because including resilient modulus of subsoil beneath track, soil deviator stress caused by train axle loads and MGT. In this paper, it is analyzed under domestic track conditions to estimate the reinforced roadbed thickness with different soil types.

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Examine the Applicability of the Thickness of Conventional Railroad Reinforced Roadbed at High-speed Railroad (일반철도 강화노반 두께의 고속철도 적용 가능성 연구)

  • Lee, Jin-Wook;Lee, Sung-Hyok;SaGong, Mynun
    • Proceedings of the KSR Conference
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    • 2011.10a
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    • pp.3166-3171
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    • 2011
  • The design standard for the thickness of reinforced roadbed is divided into high-speed and conventional railroad because dynamic characteristics of train loadings differ depending on the train speed. Due to the national plan for increasing the train speed for both conventional and new railroad lines, it is necessary to examine the applicability of concrete tracks and feasibility of the train speed increase on the conventional lines with the current thickness of the reinforced roadbed. In this study, a real-scale test was performed to monitor the dynamic characteristics of the reinforced roadbed with a thickness of 20cm and the train speed of 200km/h, 300km/h, and 400km/h. The test results were then compared with the design code to investigate the applicability of the conventional reinforced roadbed when the trains operate with higher speed.

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Characteristics of Behavior of the Crushed Stone Reinforced Roadbed under Cyclic Loading (동적하중 재하시 쇄석강화노반의 거동 특성)

  • 황선근;이성혁;이일화;최찬용
    • Proceedings of the Korean Geotechical Society Conference
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    • 2001.03a
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    • pp.525-532
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    • 2001
  • In this study, performance of reinforced railroad roadbeds with the crushed stones was investigated through the real scale railroad roadbed tests. Several real scale reinforced railroad roadbeds were constructed in the laboratory with different subgrade conditions and were tested with the estimated actual train loads including the impact loading of train. The affecting factors such as settlement, earth pressure and stress change at the surface of reinforced roadbed, subgrade layers as well as surface of rails were measured. It was found through the actual testing that for the roadbed with the same thickness, the settlement and vibration level (velocity) of reinforced roadbed decreases with the increase of reaction modulus of subgrade. The settlement of reinforced roadbed with the same reaction modulus of subgrade also decreases with the increase of thickness of the reinforced roadbed.

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Settlement Characteristics of the Reinforced Railroad Roadbed with Crushed Stones Under a Simulated Train Loading (모사 열차하중 재하에 따른 쇄석강화노반의 침하특성)

  • Hwang, Seon-Keun
    • Journal of the Korean Geotechnical Society
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    • v.20 no.2
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    • pp.5-13
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    • 2004
  • Conventional railroad roadbeds constructed with soils can easily deteriorate with time due to the increase of repeated traffic loading, increase of train speed, built-up of ground water on the roadbed and decrease of permeability in the roadbed layer, etc. In this study, performance of reinforced railroad roadbeds with the crushed stones was investigated through the real scale roadbed tests and numerical analysis. It was found that the reinforced roadbed with crushed stone had less elastic and plastic vertical displacement(settlement) than general soil roadbed regardless of the number of loading cycles. It was also found through the actual testing that for the roadbed with the same thickness, the displacement of reinforced roadbed decreases with the increase of subgrade reaction modulus. The settlement of reinforced roadbed with the same subgrade reaction modulus also decreases with the increase of thickness of the reinforced roadbed. However, the subgrade reaction modulus is a more important factor to the total plastic displacement of the track than the thickness of the crushed stone roadbed.

Determination on the Reinforced Roadbed Thickness of Concrete Track at Embankment Section (흙쌓기 구간에서 콘크리트궤도 강화노반의 두께 결정에 관한 연구)

  • Lee, Il-Wha;Lee, Sung-Jin;Sin, Min-Ho;Hwang, Sun-Kun;Lee, Chang-Jin
    • Journal of the Korean Society for Railway
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    • v.12 no.6
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    • pp.835-843
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    • 2009
  • Recently the more stable roadbed is required due to the high speed and design load. Therefore the reinforced roadbed was introduced as the solution. But the thickness and stiffness of reinforced roadbed in design code is being conservatively assessed by the foreign code without considering the domestic construction condition. In this paper, adequate Young's modulus, drain capacity, freezing depth, economical efficiency, bearing capacity, construction condition and 3-D finite element method were employed to determine the proper thickness of reinforced roadbed at the embankment section.

A Design Method of Reinforced Railway Roadbed by Geosynthetics (토목섬유로 보강된 철도노반의 설계기법)

  • 심재범;채영수
    • Proceedings of the KSR Conference
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    • 1999.11a
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    • pp.423-429
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    • 1999
  • The design method of Geosynthetics reinforced Railway Roadbed that was developed in Germany in 1997 is presently putting into practice. This method insists that Railway Roadbed Thickness has to be measured by Frost and Bearing Capacity The Maximum Value from the above two measurements is the necessary Railway Roadbed Thickness. This design method has many kinds of advantage in economic, constructive aspect, and environmentalism. Recently a few Korean experts actively have researched on this area, but their results are not enough for proper design method. Ⅰ hope more complete study on this area will be progressed.

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Sensitivity Analysis of the Factors Influencing for Decision of Reinforced Roadbed Thickness (강화노반 두께 결정을 위한 영향인자 민감도 분석)

  • Choi, Chan-Yong;Lee, Jin-Wook;Bae, Jae-Hoon;Shin, Eun-Chul
    • Proceedings of the KSR Conference
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    • 2007.05a
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    • pp.1827-1832
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    • 2007
  • The purpose of a railway track is to provide a smooth surface for safe and economical train transportation. The performance of the track results from a complex interaction of the track and subgrade components in response to train loading and environmental actions. In the past, the role of subgrade as the track foundation were not recognized adequately. There are insufficient information and inadequate methods for subgrade design, assessment and improvement. This situation has survived for a long time largely because a subgrade defect can often be adjusted by adding more ballast under the ties or applying more frequent track maintenance. Therefore, the application of reinforced roadbed technology will be expected to increase in the future. The reinforced roadbed thickness is set depending on subgrade reaction modulus$(K_{30})$ in the condition of upper subgrade through PBT in both conventional railroad and KTX railroads. As train velocity (V), train passing tonnage (N), and train axial load (P) are not considered in design, the roadbed thickness could be overestimated (or underestimated). Therefore, In this study, the computer model, GEOTRACK, was analyzed the influence of reinforced roadbed thickness factors on track modulus and the characteristics of stress pulses in track and subgrade generated by repeated axle loading.

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