• Title, Summary, Keyword: Reinforced roadbed

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Characteristics of Displacement of the Reinforced Roadbed Materials with Cyclic Loading (동적하중 재하시 강화노반 재료별 침하 특성)

  • 황선근;이성혁;최찬용
    • Journal of the Korean Society for Railway
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    • v.5 no.2
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    • pp.70-76
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    • 2002
  • In this study, performance of reinforced railroad roadbeds with the reinforced roadbed materials were investigated through the real scale roadbed tests. It was also found that the reinforced roadbed with reinforced roadbed materials has less elastic and plastic settlement than the one with soil. The slag roadbed was more effective than the crushed stone roadbed with the same condition for load distribution. Therefore considering overall characteristics of reinforced roadbed material, the optimum thickness was recommended as 50 cm. Furthermore the real scale model test under the simulated rainfall condition, the settlement in the slag roadbed was about 8 times smaller than the settlement in the soil roadbed.

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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    • 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 Study on the Applicability of the Reinforced Railroad Roadbed Method by Field Test (현장부설시험을 통한 철도 강화노반공법의 적용성에 관한 연구)

  • 황선근;신민호;이성혁;최찬용;이시한
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.215-222
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    • 2000
  • The reinforced roadbed should have the ability to spread out the load intensity lower than the bearing capacity of the subgrade of track structure as well as to prevent the softening of roadbed by providing appropriate stiffness in the roadbed, thus fully supports the track structures. Full scale reinforced roadbeds with several different types of monotoring sensors was also constructed to evaluate the performance of each reinforced roadbed through the continuous monitoring while the train operation. In this study, Field tests such as PLT, SASW were also carried out at each reinforced roadbed. The results of the field and lab tests, installation and calibration of sensors, as well as construction condition of the reinforced roadbed are presented.

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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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    • 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.

Settlement Reduction Effect of Advanced Back-to-Back Reinforced Retaining Wall

  • Koh, Taehoon;Hwang, Seonkeun;Jung, Hunchul;Jung, Hyuksang
    • International Journal of Railway
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    • v.6 no.3
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    • pp.107-111
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    • 2013
  • In order to constrain the railway roadbed settlement which causes track irregularity, and thus threats running stability and ride quality, advanced Back-to-Back (BTB) reinforced retaining wall was numerically analyzed as railway roadbed structure. This study is intended to improve conventional Back-to-Back reinforced retaining wall as the technology which would reduce the roadbed settlement in a way of constraining the lateral displacement of its prestressed vertical facing and inducing arching effects in roadbed (backfill) placed between masonry diaphragm wall and vertical facing. As a result of numerical analysis, it was found that the roadbed settlement was reduced by 10% due to the prestressed vertical facing and embedded masonry diaphragm wall of the advanced Back-to-Back reinforced retaining wall system.

A Study on Basic Properties of the Reinforced-roadbed Material Using Water Quenched Blast Furnace Slag (수재슬래그를 이용한 강화노반재료의 기초적 특성 연구)

  • 이선복;윤지선
    • Journal of the Korean Geotechnical Society
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    • v.19 no.1
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    • pp.103-110
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    • 2003
  • The development of reinforced-roadbed material in substitute for existing roadbed is necessary to protect its failure from the dynamic stress and vibration caused by the traveling of the high-speed and heavy trains. The water quenched blast furnace slag having potential hydraulic reactivity is one of the materials in substitute for soil reinforced-roadbed. We carried out the study of basic properties of roadbed material using Portland cement and CSA(calcium sulphoaluminate) as the activator for the evaluation of its application. As the result of the strength test, this material satisfied design criterion for reinforced-roadbed. Optimum mixing ratio of this reinforced-roadbed material was 15 ~ 17.5 percent of cement and 2.5 percent of CSA by weight of the blast furnace slag. Especially, as permeability is above $10^{-3}$cm/sec, this material proved to have functions of both reinforced roadbed and drainage layer.

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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    • 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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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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    • 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 Resilient Modulus of Reinforced-Roadbed Materials Using Large Repetitive Triaxial Test (대형반복삼축시험에 의한 강화노반 재료의 회복탄성계수 특성 분석)

  • Lim, Yu-Jin;Lee, Jin-Ug;Hwang, Jung-Kyu;Park, Mi-Yun
    • Proceedings of the KSR Conference
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    • pp.1115-1122
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    • 2011
  • Reinforced-Roadbed materials are usually composed of crushed stones. Repeated load application can induce deformation in the reinforced-roadbed layer so that it causes irregularity of track. Thus it is important to develop a prediction model of elastic modulus based on stress-strain relation under repeatitive load in order to investigate behavior of reinforced roadbed. The prediction model of elastic modulus of the material can be obtained from repeated triaxial test. However, a proper size of the sample for the test must be used. In this study, a large repeatitive triaxial test apparatus with the sample size of diameter of 30 cm and height of 60cm was adapted for performing test of the crushed stone reinforced-roadbed considering large particle size to get resilient modulus Mr. The obtained resilient modulus was compared to shear modulus obtained from mid size resonant column test. The sample size effect is somewhat large enough so that it is required to design a scale factor based on similarity law in order to use smaller samples for getting elastic modulus of the crushed stone reinforced-roadbed material. A scale factor could be obtained from this study.

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