• Proceedings of the KSR Conference
• /
• 2009.05a
• /
• pp.20-27
• /
• 2009

This paper presents an analytic study for replacement of the ballast track in existing subway bridge by the Precast slab panel(B2S) track. To evaluate the dynamic responses on application of B2S track, the time history analysis with the 3D modeling. A total of two models, which were one ballast track bridge and B2S track bridge, were used in the FE analysis. The results of this study show that the dynamic displacement and acceleration of the B2S track bridge were significantly reduced for a higher train speed, compared to the ballast track bridge. Also, the replacement of the ballast track bridge in existing subway bridge by the B2S track increased the structural safety of bridge and ensured sufficient dynamic stability and serviceability. As a result, the servicing subway bridge with B2S track system has need of the reasonable measures which could be reducing the static and dynamic response and improving the performance.

• Structural Engineering and Mechanics
• /
• v.61 no.6
• /
• pp.775-784
• /
• 2017

This study is devoted to developing many new substructure models for ballasted railway track by using the pyramid model philosophy. As the effect of railway embankment has been less considered in the previous studies in the field of vehicle/track interaction, so the present study develops the pyramid models in the presence of railway embankment and implements them in vehicle/track interaction dynamic analyses. Considering a moving car body as multi bodies with 10 degrees of freedom and the ballasted track including rail, sleeper, ballast, subgrade and embankment, two categories of numerical analyses are performed by considering the new substructure systems including type A (initiation of stress overlap areas in adjacent sleepers from the ballast layer) or type B (initiation of stress overlap areas in adjacent sleepers from the subgrade layer). A comprehensive sensitivity analyses are performed on effective parameters such as ballast height, sleepers spacing and sleeper width. The results indicate that the stiffness of subgrade, embankment and foundation increased by increasing the ballast height. Also, by increasing the ballast height, rail and ballast vertical displacement decreased.

• Journal of the Korean Society for Railway
• /
• v.10 no.2 s.39
• /
• pp.167-178
• /
• 2007

In general, it is known that the concrete ballast track is possible to reduce a cost of maintenance activities cause of maintenance free by restrictive maintenance in application of track ballast structures. However, if deteriorations and fracture mechanism of a material are considered, proper maintenance activities and repairing are continually required. For the problems, we evaluated an economical efficiency of the gravel ballast and the concrete ballast on a proper level of maintenance activities. As the method based on history path is difficult to obtain sufficient reliabilities cause of an absence of real data for maintenance activities, we chose the delphi survey method by professional group, and we obtained the appropriate index and profiles for maintenance activities. As a result, we founded that effects for cost reduction can be expected by preventive maintenance management, and we proposed economical restrictions and life cycle cost for track ballast structures in a life cycle.

• Journal of the Korean Society for Precision Engineering
• /
• v.29 no.6
• /
• pp.593-599
• /
• 2012

To analyze the effect of the track structure on the running performance of the railway vehicle, we studied on the vibration and ride characteristics of the high speed train. As results, vibration and ride level of high speed train on the concrete bed track is more reduced than on the ballast bed track. Peak-peak value of carbody vibration on the concrete bed track at 300km/h is half of the peak-peak value of carbody vibration on the ballast bed track. Ride level on the concrete bed track at 300km/h is same level as that on the ballast bed track at 250km/h. Thus, Vibration and ride performance of the high speed train on the concrete bed track is greatly improved compared with that on the ballast bed track.

• Proceedings of the KSR Conference
• /
• 2003.10b
• /
• pp.27-34
• /
• 2003

This Study is about adoption of slab track on the new high speed railway line between Daegu and Busan. While ballast track currently used is easy to construct with low investment, the error margin of rail track occurs in the track due to the repetition load of the train. Therefore, repairs should be carried out all the time to put the railway track at the repair level or less. In addition, noise caused by such repairs has become a new social problem at night. Construction costs for slab track are about 1.3-1.5 times higher than those for ballast track. However, slab track will save labor costs by solving various problems of ballast track. In this regard, it is feasible to adopt slab track on the new high speed railway line between Daegu and Busan.

• Proceedings of the KSR Conference
• /
• 2008.06a
• /
• pp.268-273
• /
• 2008

The ballast, one of track components, plays an essential role as intermedium in transmitting train load to subgrade safely, and the deterioration of ballast directly effects the growth of track irregularity. So far, gravel fining of ballast track was mainly related to the repetition of train loads, but was gradually increased with using MTT(Multiple Tie Tamper) recently. Therefore, in this study, an evaluation of the abrasion and crush process of ballast particles was performed with outdoor field test by MTT works. From this study, the amount of abrasion and crush of ballast particles appeared to increase linearly with MTT works, and the gradient of particle size distribution curve appeared to deviate gradually from a criterion of aggregated ballast size distribution in high-speed railroad.

• Journal of the Korean Geotechnical Society
• /
• v.21 no.5
• /
• pp.163-170
• /
• 2005

Track substructure (ballast, subgrade) should have sufficient strength and uniform stiffness to fully support track superstructure (rail, fastener, sleeper). Vertical support stiffness of track is strongly influenced by the condition of ballast and subgrade layers. Therefore, the evaluation of the condition of track substructure is very important to evaluate the vertical support stiffness of track. This paper proposes the trackbed evaluation system, which is composed of Ground Penetrating Radar (GPR), Portable Ballast Sample. (PBS), and Light Falling Weight Deflectomete. (LFWD), to diagnose track substructure. The laboratory and field tests are performed to evaluate the applicability of the proposed trackbed evaluation system.

• Proceedings of the KSR Conference
• /
• 2011.05a
• /
• pp.162-166
• /
• 2011

In railway, Tie supports rail and plays a role that distribute train load to the ballast. Also, Tie and ballast resist against external force and fix the track position. But, weakening resistance of ballast and tie cause vertical displacement of tie and track irregularity. For reinforcement of track stiffness and reduction of track irregularity, KORAIL has developed Multi Branch type tie(GLORY Tie) that reinforced resistance than general PCT and installed in order to test in the field. This study measured and analyzed lateral resistance of ballast, wheel load of rail, bending strain of rail foot, vertical displacement and vibration acceleration of tie in order to evaluate performance of Multi Branch type tie in the field. According to the results of test, Multi Branch tie is excellent than general tie about lateral resistance of ballast and vertical displacement of tie. And, gap of measurement value between Multi Branch type tie and general tie about wheel load of rail, bending strain of rail foot were very small.

• Journal of the Korean Society for Railway
• /
• v.12 no.1
• /
• pp.167-174
• /
• 2009

Due to the travelling of the train with high speed the period of maintenance activities of the ballasted track is coming to be short, and more from the residential area of the ballasted track tunnel circumference the civil appeal is increasing with railroad vibration problem. To reduce the vibration problem and a maintenance cost establishes the ballast mat in the tunnel within part segment. In this study, to estimate the vibration reduction effect of the ballast mat we have done a comparative analysis with the vibration field test by the transit train by at the ballasted track with ballast mat and the standard ballasted track without vibration protection in tunnel.

• Journal of the Korean Society for Railway
• /
• v.12 no.4
• /
• pp.481-487
• /
• 2009

On the paved track, the railway ballast is used as aggregate for the filling layer using the pre-packed concrete method. The condition of ballast as the paved track aggregate ensure that the compressive strength, particle distribution size for the pouring and surface clearance to increase the adhesive strength with mortar. It is profitable to recycle the existing railway ballast as a economical supply. In order to increase recycling characteristic, it is necessary to apply the similar criterion which does not exceed the conventional railway ballast criterion. Consequently, this paper was to investigate physical characteristics of existing ballast, particle size distribution, compressive and flexural strength, bearing capacity and filling capacity to prepare the aggregate's recycling. As a result, optimized aggregate criterion is suggested.