• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.980-986
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• 2004

So far systematic and reliable methods for the investigation of track substructure (ballast and subgrade) are not developed yet. This study presents the applicability of GPR (Ground Penetrating Radar) and PBS (Portable Ballast Sampler) to the evaluation of railway trackbed conditions. Including FWD (Falling Weight Deflectometer) often used to evaluate the subsurface conditions of pavement, the standard system for assessing trackbed conditions will be developed in the future.

• 한국철도학회논문집
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• 제9권1호
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• pp.118-124
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• 2006

SThe rigidities of bridge substructures are the important data in the rail-bridge interaction analysis in Korean High -Speed Railway. This experimental study is being performed because of followings. 1) More correct longitudinal stiffness of the structure including substructure should be considered in the calculation of stresses in rails. 2) There are many uncertainties in the design and construction of the piers and foundations. 3) Actual guideline for the rigidities of piers and foundations in the design is necessary. 4) Measurement on the rigidity of pier according to the types of piers, foundations and soil-conditions is needed. Curve for estimating the total rigidity of substructure will be obtained through this and further experimental studies. It may be used in the analysis of Korean High-Speed Railway bridge and then, longitudinal stresses in the rails can be estimated more accurately. One pair of piers, which consist of pot-bearing for fixed support and pad-bearing for movable support, are loaded by steel frame devices with steel wire ropes and hydraulic jack. The responses which are measured at each loading stages in those field tests are displacements and tilted angles on the top and bottom of piers. This study is being performed testing and analysis about several piers in the construction field.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.1191-1198
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• 2011

The railway business was began at England in 1767. Since then, it has been changed for configuration of rail over the years and made in the form of I. The train propulsion has been developed in a engine of steam, diesel, motor, electromagnetic force and a pneumatic engine, continuously. also, the friction has been improved in a steel-wheel, rubber tire, frictionless maglev system and railless system. In consequence, the efficiency and improvement speed for train have been accomplished. In this paper, it is investigated for the structure with lightweight using the change for supporting the form of lateral pressure by centrifugal force in the substructure supporting load for railway vehicles.

• Geomechanics and Engineering
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• 제20권2호
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• pp.155-164
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• 2020

In recent years, the stability, safety and comfort of trains has received increased attention. The mechanical characteristics and differential settlement of the foundation are the main problems studied in high-speed railway research. The mechanical characteristics and differential settlement of the foundation are greatly affected by the ground treatment. Additionally, the effects of train load and earthquakes have a great impact. The dynamic action of the train will increase the vibration acceleration of the foundation and increase the cumulative deformation, and the earthquake action will affect the stability of the substructure. Earthquakes have an important practical significance for the dynamic analysis of the railway operation stage; therefore, considering the impact of earthquakes on the railway substructure stability has engineering significance. In this paper, finite element model of the CFG (Cement Fly-ash Gravel) pile + cement-soil compacted pile about composite foundation is established, and manual numerical incentive method is selected as the simulation principle. The mechanical characteristics and differential settlement of CFG pile + cement-soil compacted pile about composite foundation under train load are studied. The results show: under the train load, the neutral point of the side friction about CFG pile is located at nearly 7/8 of the pile length; the vertical dynamic stress-time history curves of the cement-soil compacted pile, CFG pile and soil between piles are all regular serrated shape, the vertical dynamic stress of CFG pile changes greatly, but the vertical dynamic stress of cement-soil compacted pile and soil between piles does not change much; the vertical displacement of CFG pile, cement-soil compacted pile and soil between piles change very little.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집 특별세미나,특별/일반세션
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• pp.437-443
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• 2009

Generally speaking, the uniqueness of Korea for the high-speed railway rolling-stock is mainly perceived through the travel over the high-speed electric railway by passengers, which consists of the organization of space in the coach and its interior design. For such purpose, it is necessary to build a series of independent cultures with high-speed railway i.e. to have the development of design technologies oriented to harmonizing human beings, their society and culture with the systematic integration of production technologies to support the culture and its substructure foundation which constitute the frame of superstructure in the society, by defining the relationships with travelers on the high-speed railway as well as enhancing the comfort and convenience of high-speed railway through drawing up the development of links with the systematic integration among lines of technologies on the basis of 'User Train Interface. This thesis aims at introducing the study carried out to build the evaluation standards of performance outputs for 'HEMU-400X rolling-stock Design' derived from the performance for the first year in the research 'Development of Technologies for the Next-Generation High-Speed Railway' as part of "Development Project for the Future Railway Technologies" from 2007.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.1254-1261
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• 2011

Application of long-span bridge, which is affected by parameters such as span length, shoe boundary condition, track property and stiffness of superstructure and substructure etc., can vary. Especially, by CWR aspects of the axial force, long-span high speed railway bridges are limited at type and span length. In this study, in terms of CWR axial force, the long-span high-speed railway bridges without REJ(Rail Expansion Joint) is to propose the bridge type. Various Parameters analysis performed for the proposed type(Arch bridge, Cable-stayed bridge).

• Geomechanics and Engineering
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• 제14권6호
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• pp.563-570
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• 2018

Ballast layer has an important role in vertical stiffness and stability of railway track. In most of the Middle East countries and some of the Asian ones, significant parts of railway lines pass through desert areas where the track (particularly ballast layer) is contaminated with sands. Despite considerable number of derailments reported in the sand contaminated tracks, there is a lack of sufficient studies on the influences of sand contamination on the ballast vertical stiffness as the main indicator of track stability. Addressing this limitation, the effects of sand contamination on the mechanical behavior of ballast were experimentally investigated. For this purpose, laboratory tests (plate load test) on ballast samples with different levels of sand contamination were carried out. The results obtained were analyzed leading to derive mathematical expressions for the strain modulus ($E_V$) as a function of the ballast level of contamination. The $E_V$ was used as an index for evaluation of the load-deformation characteristics and bearing capacity of track substructure. The critical limit of sand contamination, after which the $E_V$ of the ballast reduces drastically, was obtained. It was shown that the obtained research results improve the current track maintenance approach by providing key guides for the optimization of ballast maintenance planning (the timing of ballast cleaning or renewal).

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.561-566
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• 2003

In this paper, a numerical method for evaluating the efficiency of vibration reduction of substructure under floating slab track is developed for optimal design of floating slab track. The equation of motion for train and track interaction system is derived by applying compatibility condition at the contact points between wheels and rails. The train is modelled by 3-masses system and the track by continuous support beam system. Numerical analyses are carried out to investigate the effects of train speed, stiffness and damping of slab-pad, and track irregularity upon vibration reduction in substructure under the track.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.3160-3165
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• 2011

The track and bridge interaction should be considered for the safety check of railway bridge design as the longitudinal forces transmitted to rail and bridge are changed by longitudinal stiffness of bridge system. The longitudinal stiffness of bridge structures is determined by the magnitude of the ballast resistance, the expansion length of superstructure, and longitudinal stiffness of substructure including pier and foundations. In this study, the main factors affect on the longitudinal rail forces are discussed and the computational parametric analysis of rail forces considering rail-bridge interactions. And the required range of stiffness of sub-structures and span length for the assurance of safety of CWR(continuous welded rail) track is suggested.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.1452-1459
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• 2010

Application of long-span bridge, which is affected by parameters such as span length, shoe boundary condition, track property and stiffness of superstructure and substructure etc., can vary. Especially, by CWR aspects of the axial force, that can be less constraints of construction depending on whether the application of rail expansion joint(REJ), which has disadvantaged in terms of maintenance. In this study, it was performed parameter study for multiple variables (shaft length, the upper and lower cross-section characteristics, track characteristics, etc.) in terms of CWR aspects. Structure-rail interaction analysis was applied to the typical simple span PSC Box and 3 span continuous bridge Extradosed Bridge(50m+80m+50m) excluding REJ. If you set the boundary e of variables for long-span railway bridge excluding REJ through the this study, when designing future is expected to be able to useful.