• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.334-339
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• 2002

In this report, numerical investigations have demonstrated, that the displacement underneath a moving loading reach a maximum value, if the speed of the load is equal to propagation velocity of the maximum wave. The load speed for which the maximum displacement occurs is called critical speed. The critical speed divides the velocities in a subcritical and a super-critical region. By means of calculations the dynamic behaviour of the slab track-soil is investigated. For concrete slab track dynamic wheel load are given in dependence of relevant excitation mechanismen and speed of the train. These loads can be used for the dimensioning of the track as well as for prognosis of the vibrations at the track and the surrounding soil.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.6788-6798
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• 2015

In recent high speed rail way, the operating speed of train is enhanced and the introduction of EMU train vehicles is increased. In addition, as expected the demand of the concrete slab track and the trend of design cross-section reduction, the clear behavior of evaluation of internal slab layer is demanded about the variation of design load and speed. The purpose of this study is to evaluate and identify the mechanical behavior pattern of concrete slab track and track-road bed with the variation of axle load and train speed. To this end, the behavior of TCL and HSB was evaluated in according to the variation of axle load and speed. And the analysis results and the data measured TCL strain sensor, which was embedded in TCL slab under installation on Honam high speed railway, was analyzed. The analysis result shows that the strain are increasing in according to the speed-up of train, and line regression was obtained from measured data. Analysis data of the state of bonding condition of slab layer and measured data was analyzed. It is conducted that the TCL layer stress of HEMU 430X, which of axle load, is lighter was similar to the stress of KTX-Honam, the standard deviation of measured stress is dramatically increased.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3201-3207
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• 2011

This paper reviewed wave propagation of train vibration based on the study of high speed railway soft ground section with pile slab construction. In a filed of railway, concrete track has been adapted in a railway construction. And in order to maintain its track, soil improving method was required to control residual settlement. Within many soft ground settlement prevention techniques, pile slab method has an effect of minimizing residual settlement of soft ground. This is possible using support embankment load method by construct pile slab or cap the upper soft ground. This paper reviewed vibration wave characteristic of soft ground section with pile slab using numerical analysis application through finite element analysis. Pile slab method is established between high stiffened soft ground and embankment this creates a possibility of vibration block or slab amplification. Thus analyzed of wave propagation was done with roadbed and structure property to confirm application performance of pile slab method of high speed railway structure.

• Structural Engineering and Mechanics
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• v.78 no.2
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• pp.163-174
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• 2021

Track-bridge interaction has become an essential part in the design of bridges and rails in terms of modern railways. As a unique ballastless slab track, the longitudinal continuous slab track (LCST) or referred to as the China railway track system Type-II (CRTS II) slab track, demonstrates a complex force mechanism. Therefore, a comprehensive track-bridge interaction study between multi-span simply supported beam bridges and the LCST is presented in this work. In specific, we have developed an integrated finite element model to investigate the overall interaction effects of the LCST-bridge system subjected to the actions of temperature changes, traffic loads, and braking forces. In that place, the deformation patterns of the track and bridge, and the distributions of longitudinal forces and the interfacial shear stress are studied. Our results show that the additional rail stress has been reduced under various loads and the rail's deformation has become much smoother after the transition of the two continuous structural layers of the LCST. However, the influence of the temperature difference of bridges is significant and cannot be ignored as this action can bend the bridge like the traffic load. The uniform temperature change causes the tensile stress of the concrete track structure and further induce cracks in them. Additionally, the influences of the friction coefficient of the sliding layer and the interfacial bond characteristics on the LCST's performance are discussed. The systematic study presented in this work may have some potential impacts on the understanding of the overall mechanical behavior of the LCST-bridge system.

• Structural Engineering and Mechanics
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• v.66 no.1
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• pp.15-25
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• 2018

Post-construction subgrade settlement especially differential settlement, has become a key issue in construction and operation of non-ballasted track on high-speed railway soil subgrade, which may also affect the dynamic performance of passing trains. To estimate the effect of differential subgrade settlement on the mechanical behaviors of the vehicle-slab track system, a detailed model considering nonlinear subgrade support and initial track state due to track self-weight is developed. Accordingly, analysis aiming at a typical high-speed vehicle coupled with a deteriorated slab track owing to differential subgrade settlement is carried out, in terms of two aspects: (i) determination of an initial mapping relationship between subgrade settlement and track deflections as well as contact state between track and subgrade based on a semi-analytical method; (ii) simulation of dynamic performance of the coupled system by employing a time integration approach. The investigation indicates that subgrade settlement results in additional track irregularity, and locally, the contact between the concrete track and the soil subgrade is prone to failure. Moreover, wheel-rail interaction is significantly exacerbated by the track degradation and abnormal responses occur as a result of the unsupported areas. Distributions of interlaminar contact forces in track system vary dramatically due to the combined effect of track deterioration and dynamic load. These may not only intensify the dynamic responses of the coupled system, but also have impacts on the long-term behavior of the track components.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.419-431
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• 2007

The track and rail surface geometry is of prime importance on the requirement for track dynamic stiffness, particularly for the speed of 350 km/h, for which both the requirement for fatigue and tensile strength limits require a lower stiffness than 100 kN/mm, which is near the value for ballasted track. However, the track quality has been considered as being the same for 350 km/h as that for 300 km/h, and based on ballasted track, and the track geometry may be kept in better condition with a slab track(probably more similar to the medium quality track geometry of ballasted track). In conclusion, under the condition that the track geometry quality provided by the concrete slab system is fairly good, and that the required maintenance is applied to the rail surface, there would be no safety risk if the fastening system point stiffness reaches 160 kN/mm for 300 km/h operation, and 110 N/mm at 350 km/h.

• Magazine of the Korea Concrete Institute
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• v.16 no.4 s.81
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• pp.10-17
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• 2004

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1303-1313
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• 2013

In this study, the reference values for the internal forces of the rail supports caused by a wheel load, a unit vertical displacement, a unit end rotation in examination of the serviceability of concrete slab track bridge were obtained. In analysis, the analysis models of which the rail was continuously and discretely supported by elastic springs were used. The internal forces of the rail supports from the analysis were compared with the results provided in the DS 804 regulations and agreed with well. In addition, the effects of the space between the rail supports and the stiffness of fastener on the internal forces of the rail supports were investigated.

• Journal of the Korean Society for Railway
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• v.14 no.4
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• pp.348-353
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• 2011

Iron fillings which were accumulated around the rail was often the cause of abnormal signal in case of signaling equipment using rail as transmission line. Iron fillings were generated on curved section of railroad due to the friction between rail and wheel, and metro line company urged to find the way to remove these iron fillings, because these were often the cause of abnormal signal. Magnetic device for trapping iron fillings around concrete slab tracks is introduced. The characteristics of magnetic device were analyzed using basic design and numerical analysis method. Magnetic device for trapping iron fillings were examined for application to the train which were operating in commercial line.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.836-841
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• 2004

Recently, the development of the paved track is required as a Low-maintenance of conventional line. The main reason is that the line capacity and bearing of track are increased progressively. The most important factor of paved track is stability and applicability. To be based on this subject, Cement Mortar Pouring(CMP) paved track is developed. CMP paved track is a kind of ballast reinforced track using the pre packed concrete technique. The most important to design is characteristics of the structure. CMP slab's thickness is less than the conventional slab track and pouring layer is attached tie and roadbed directly. On this paper, to verify the basic structure of the CMP track, characteristics of the structure is investigated pouring layer, tie and interaction of the each layer using the 3D finite elment analysis.