• Title, Summary, Keyword: Roadbed design standard

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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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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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    • 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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Development of Design Method for Reinforced Roadbed Considering Plastic Settlement for High-speed Railway (고속철도에서의 소성침하를 고려한 강화노반 설계기법 개발)

  • Choi, Chan-Yong;Choi, Won-Il;Han, Sang-Jae;Jung, Jae-Hyun
    • Journal of the Korean Geotechnical Society
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    • v.29 no.9
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    • pp.55-69
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    • 2013
  • An alternative design method of existing methods based on elastic theory the design method of roadbed considering plastic deformation of roadbed and stress-strain at roadbed materials with the cyclic loading of trains passing. The characteristics of the developed design method considering traffic load, number of cyclic loading and resilience modulus of roadbed materials can evaluate elastic strain as well as plastic settlement with allowable design criteria. The proposed design method is applied to standard roadbed section drawing of HONAM high-speed railway considering design conditions such as allowable elastic and plastic settlement, train speed, the tonnage of trains. As a result, required levels of resilience modulus model parameter ($A_E$), unconfined compressive strength, types of soil material were evaluated.

Characteristics of Roadbed Behaviors of Concrete Track for High-Speed Railway (고속철도 콘크리트궤도용 흙노반의 거동 특성)

  • Lee Il-Wha;Lee Su-Hyung;Kang Yun-Suk
    • Journal of the Korean Society for Railway
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    • v.9 no.3
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    • pp.298-304
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    • 2006
  • An active application of concrete track is being expected for the future constructions of Korean railroad. For the successful concrete track construction and design in earthwork areas, the roadbed behavior should be reasonably estimated using the proper analysis method. In this paper, behaviors of concrete track on the reinforced roadbed constructed with the standard stiffness and depth were estimated thorough numerical analyses and field measurements. A three dimensional finite difference method was employed to model the concrete tracks and subground. The settlement and vertical pressures caused by train load were estimated by the numerical method and compared with the field measurement results. The bearing characteristics of roadbed were presented and the proper method for the analysis of concrete track was proposed.

Prediction of Cumulative Plastic Displacement in the Concrete Track Roadbed Caused by Cyclic Loading (반복하중에 의한 콘크리트 궤도 노반의 누적 소성 변위 예측)

  • Won, Sang-Soo;Lee, Jin-Wook;Lee, Seong-Hyeok;Jung, Young-Hoon
    • Journal of the Korean Society for Railway
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    • v.17 no.1
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    • pp.52-58
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    • 2014
  • Plastic deformation of roadbed influences the stability and maintenance of concrete slab track. Long-term plastic deformation in a railway roadbed is generated primarily due to accumulated inelastic strains caused by repeated passing of trains. Prediction of cumulative plastic deformation is important in cost-effective maintenance of railway tracks as well as for the safe operation of trains. In this study, the vertical displacements in railway roadbeds with different thicknesses of reinforced roadbed were computed. Parameters of the power model for cumulative plastic strain were calibrated by using the data from triaxial tests and full-scale loading tests. Results of three-dimensional finite element analyses of standard roadbed sections provide us with design guidelines for the selection of the thickness of reinforced roadbed.

Evaluation on the Applicability of the Conventional Roadbed Stiffness for High Speed Concrete Track (일반철도 노반 강성조건에서의 고속철도용 콘크리트 궤도의 적용성 검토)

  • Lee, Jin Wook;Lee, Seong Hyeok;SaGong, Myung;Lyu, Tae Jin
    • Journal of the Korean Society for Railway
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    • v.16 no.1
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    • pp.40-46
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    • 2013
  • Based on Korean railway design standards, the thicknesses of the reinforced roadbeds of conventional and high speed railways are different, and so too, for the size distribution of the ballast particles. Accordingly, considerable cost would be required to increase operating speeds of conventional lines, in particular related to changing from a ballasted track system to a ballastless one. In this study, applicability of a roadbed which supports conventional ballasted track, for use as a ballastless track for a high speed rail line was examined. A reinforced roadbed for a conventional railway is 20cm thick, and the type of material used for a conventional reinforced roadbed is M-40 (crushed gravel for road embankments). A dynamics test was conducted to evaluate the occurrence of the permanent settlement of the track substructure. These results suggest that, without changes to the track substructure, an operational speed of 400km/h is feasible with a ballastless track. This result; however, is from laboratory experiments. Further studies, such as numerical analyses or field validation, are required.

A Development of Railway Infrastructure BIM Prototype Libraries for Roadbed and Track (노반, 궤도분야 철도인프라 BIM 원형 라이브러리 구축)

  • Park, Hyung-Jin;Seo, Myoung-Bae
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.30 no.5
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    • pp.461-468
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    • 2017
  • The introduction of BIM in domestic construction industry has become more active. Library development and standardization in civil-engineering are unexhausted. This research develop and standardize prototype library for railway infrastructure. We define target facility for library based on railway standard drawings and select BIM software according characteristic of each facility. In this research, we develop libraries composed of 199 files and 489 types for alignment, roadbed and track and make specifications as defined attribution item and description. As we consider for application to diverse use case, develop prototype library in low LoD. We expect that library can increase 3D design productivity and ensure consistency of quality.

Behavior Characteristics of Railway Roadbed Retained by Geosynthetic Reinforced Segmental Wall Under Train Load (열차 하중 작용 시 블록식 보강토 옹벽으로 지지된 철도 노반의 거동)

  • Lee, Seong Hyeok;Choi, Chan Yong;Lee, Jin Wook
    • Journal of the Korean Society for Railway
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    • v.15 no.5
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    • pp.467-475
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    • 2012
  • Static and dynamic train load tests were conducted to evaluate the train load transfer mechanism in the roadbed which was retained by two types (fully and partially) of segmental retaining walls reinforced by geogrid. The test roadbed was 2.6m high, 5m wide, and 6m long. A combination of earth pressure gages, displacement transducers, and strain gages were placed in specific locations to measure the responses. Test results showed that the wall displacement pattern as well as the earth pressure for the fully reinforced retaining wall was different from those for the partially reinforced retaining wall. In the dynamic train load test, the strain in the upper part of the wall tended to decrease, and both the residual deformation and the rate of the deformation were significantly lower than those in the current design standard.

Dynamic Properties for Geomaterials of Railway as Determined by Large-scale Cyclic Triaxial Test (대형삼축압축시험을 이용한 철도노반재료의 동적 물성 제안)

  • Lee, Sung Jin;Hwang, Su Beom;Lee, Su Hyung;Lee, Seong Hyeok;Kim, Ki Jae
    • Journal of the Korean Society for Railway
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    • v.17 no.1
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    • pp.43-51
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    • 2014
  • In the earth structures of railways, large coarse granular materials are widely used as fill materials. However, experimental studies that consider the dynamic properties of these coarse granular materials have rarely been carried out in Korea due to the lack of a large scale test apparatus in this country. In this study, large scale cyclic triaxial tests were carried out for materials such as reinforced roadbed (subballast, graded crushed stone), transition zone gravel, and the upper subgrade of a railway. These specimens were prepared according to certain conditions (dry unit weight, grain size distribution, and so on) specified in the Korea railroad design standard. Based on these large triaxial test results, normalized shear modulus and damping ratio curves according to small strain level are suggested. A model and coefficients for each material are also proposed.

Design of the Railbeam Lengths at the Roadbed (철도 레일빔 설계법에 대한 연구)

  • Jung, Hyuksang
    • Journal of the Korean Geoenvironmental Society
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    • v.17 no.1
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    • pp.21-28
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    • 2016
  • This paper deals with contents on the estimation of rail beam from the geotechnical engineering aspect. Rail beam is reinforced rail installed on the inside and outside of rail to prevent differential settlement during the construction period of railroad crossing construction. Such rail beam is frequently being installed to ensure stability of existing railroad facilities because of increasing constructions of underground structures crossing railroad in recent. However, there is a difficulty in design due to lack of design standard on rail beam length. Furthermore, derailing accidents are also occurring as a result of rail beam length shortage. Accordingly, this paper presented flow chart based on the classification into soil ground and bedrock ground for the rail beam length estimation. In addition, case study was conducted on rail combination and location through which effective rail combination and location were ensured.