• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1303-1308
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• 2007

Recently, precast concrete tracks are replacing ballast track for efficient and economic maintenance of track. Precast concrete railroad tracks are manufactured in factory, and transported to railroad construction site for installation. Therefore, quality of precast concrete track itself should be sufficiently good. On the contrary to the convenient manufacturing of precast concrete track, the installation of a precast concrete track requires careful steps. Typically, a precast concrete track is placed on an approximately 15-cm thick lean concrete layer. A mortar is filled between lean concrete layer and precast concrete track to adjust the sloping angle of a precast concrete track for a safe train operation at a curvy section. Then, the use of filled mortarproduces a void underneath a precast concrete track, which is harmful to structural safety of a precast concrete track undercyclic loading. Therefore, it is essential to make sure that there is no void left beneath a precast concrete track after mortar filling. In the continuous resonance method, the amplitude of frequency response measured using an instrumented hammer and an accelerometer is plotted against a pseudo-depth, which is half of the wave velocity divided by frequency. The frequency response functions are measured at consecutive measurement locations, 6-cm interval between measurement points, and then combined together to generate a 2-D plot of frequency response. The sections with strong reflections or large amplitude of frequency response are suspicious areas with internal voids and unfilled areas. The 2-D frequency response plot was efficient in locating problematic sections just by examining the color shade of a visualized plot in 2-D format. Some of the problematic sections were drilled to make a visual inspection of mortar filling. The visual image of interface between mortar and precast concrete track was verified using the validity of the continuous resonance technique adopted in this research.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.438-443
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• 2007

In the recent railway construction, the concrete slab track is highlighted as the maintenance-free track and the main stream is moving from ballasted track to concrete slab track. However, in spite of many merits of concrete slab track, the higher noise generated from the concrete slab track is a troublesome question to solve and, by this reason, many studies on noise reduction of concrete slab track are carried out. The railway noise can be classified into the reflection noise emitted from wheel/rail contact and the structure-borne noise transmitted through railway structures. In this presentation, we would like to introduce an example of the successful reduction of structure-borne noise at track retrofitting to maintenance-free concrete slab track in elevated Changdong Station which was built with ballasted track on Rahmen structure.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.332-336
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• 2011

IN THIS STUDY, BASED ON THE TYPE OF HIGH SPEED RAILWAY TRACK VIBRATION CHARACTERISTICS WERE MEASURED AT KTX VEHICLE. KTX ROUTE BALLASTED TRACK HAS BEEN INSTALLED TOGETHER WITH THE CONCRETE TRACK. CONCRETE MUST BE TRACK IRREGULARITY THAN BALLASTED TRACK, VEHICLES VIBRATION VALUES THAT ARE SMALLER. ALSO, IN TERMS OF MAINTENANCE, CONCRETE TRACK IS KNOWN TO BE MORE FAVORABLE THAN THE BALLASTED TRACK. PHASE 2 IS THE KTX, DAEGU - BUSAN IS A SECTION OF CONCRETE TRACK. IN THIS STUDY, "KUUNG-BU HIGH-SPEED RAILWAY LINES" INSTALLED ON THE CONCRETE TRACK AND BALLASTED TRACK KTX FROM THE VEHICLE WHEN INSTALLED BETWEEN RAILS, SLEEPER AND BALLAST ON THE TRACK WAS MEASURED VIBRATIONS.

• International Journal of Railway
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• v.6 no.2
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• pp.59-63
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• 2013

The purpose of this paper was to evaluate the effectiveness of geogrid for conventional ballasted track and asphalt concrete underlayment track using PLAXIS finite element program. Geogrid element was modeled at various locations that include subballast/subgrade, subballast/ballast interfaces, middle of the ballast, and one-third depth of the ballast. The results revealed that the effectiveness of geogrid reinforcement appeared to be larger for ballasted track structure compared to asphalt concrete underlayment track. Particularly, in case of installing geogrid at one-third depth of ballast layer in a conventional ballasted track, the most effectiveness of geogrid reinforcement was achieved. The influence of geogrid axial stiffness on track substructure response was not clear to conclude. Further validations using a discrete element method along with experimental investigation are considered as a future study. The effect of asphalt concrete layer modulus was evaluated. The results exhibited that higher layer modulus seems to be effective in controlling displacement and strain of track substructure. However it also yields slightly higher stresses within track substructure. It infers that further validations are required to come up with optimum asphalt concrete mixture design to meet economical and functional criteria.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.671-679
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• 2010

The construction of concrete track for the first time in Korea gives lots of meanings to civil engineering in various aspects. Settlement level needs to be kept minimal for the safety of the track. Concrete track has different structural characteristics comparing to conventional ballast track, so load distribution in concrete track is also different. Since it is the first time to build concrete track, there are very few experience and data available on the subject. Therefore it is important to evaluate how much load is transferred to the ground due to the running vehicle in concrete track and to determine the optimal thickness of layers. In this research, 9 individual earth pressure cells were installed at OOOk930 site in 2nd stage of Kyungbu high speed railway during under construction. The in-situ pressure data were measured at each layers during pump-car and locomotive were moving on the high speed railway surface.

• Journal of the Korean Society for Railway
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• v.19 no.4
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• pp.506-514
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• 2016

Experimental ballast track and concrete track were installed on the railway site and the frost penetration depth and the frost heave amount in the winter were measured. As a result, when the freezing index was the same, the frost penetration depth of concrete track was deeper than that of ballast track. Furthermore, when an XPS and polyethylene aggregate layer was installed below the ballast track, the frost penetration depth of the ballast track decreased significantly; in the case of the concrete track, the frost penetration depth decreased when the thickness of the subbase increased. Meanwhile, the frost heave amount also decreased when an XPS and polyethylene aggregate layer was installed below the ballast track ; in the case of the concrete track, the frost heave amount decreased when the thickness of the subbase increased.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1223-1228
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• 2007

Since KHSL 2nd phase was adapted as a main track design, the interests of concrete slab track system have been gradually increased in the division of rail track engineering and many engineering companies have been trying to adapt a concrete slab track system at this moment. Advantages of this system proved in advanced country, japan and Germany etc. are excellent maintenance, track stability and increasing of buckling resistance This developed turnout is same with the KHSR 1st phase's design and applications rules, components and signaling system since it observes KTX specification. Comparing it with the former turnout, High-elasticity pad, lubrication-free roller slide plate and Rheda2000 PC sleeper are only different. The purpose of this study is the development of high speed turnout on concrete slab track and its application on site. Now these studies are going to show the verification and confidence about the interface between ballast-track and concrete slab track by finding and solving the possible problems when it is installed on site and to make these turnouts applied perfectly and completely on concrete slab track. Its first trial construction in korea had been successfully completed at Sangju-station on July 20th ,2007 thanks to KORAIL and KR. Hereunder Sampyo E&C trys to introduce all of turnout technologies on concrete slab track system with Rheda 2000 sleeper

• Journal of the Korean Geosynthetics Society
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• v.9 no.3
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• pp.1-8
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• 2010

The track systems installed in Korea railway consist of two types on ballasted track or ballastless track. In this study, it was compared with difference of the behaviors at roadbed with cyclic loading through full scale model test. From the results of model tests, loading distribution ratio of the concrete slab track become more widely distributed than ballasted track, and loading distribution ratio at concrete track was about 30:20:15. The concrete slab track is likely to behavior of the rigid plate, while ballasted track is such as flexible pavement. The vertical stresses of upper roadbed with traffic cyclic loading in concrete track were measured about 30 kPa or less. It was a scene very similar to the results of the field train running test. The vertical stress at concrete track was occurred approximately 4 times smaller than ballasted track. Also, the soil velocities with cyclic loading at the slab track were occurred about 0.3 cm/sec or less, its 8 times smaller than ballasted track.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3214-3219
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• 2011

HONAM High Speed Railway project is under construction with the target to have 350km/h design speed from Songjeong Gwangju City to Osong. The track for the whole section of the line is scheduled to be a concrete track in order to decrease total life cycle cost (LCC) according to the decrease of track destruction. However, the study on the related parts to increase the train speed up to 400km/h is on going in order to strength the competitiveness of high speed railway. On this study, the stress of track has been analyzed according to the concrete track design method of Eisenmann using equivalent depth theory proposed by Odemark for behavior analysis of concrete track on track bed, which is having embankment deformation characteristics by train load. The behavior analysis of track is performed to analyze the stress of track bed layer and track according to the variation of design load and train speed. And also, the characteristics of concrete track have been figured out by analyzing the parameter according to the thickness of track bed layer.

• Journal of the Korean Society for Railway
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• v.9 no.6 s.37
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• pp.644-651
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• 2006

An application of concrete track is being actively processed for the construction of Korean railroad. The concrete track has an advantage to decrease the maintenance ire, but is very difficult system to maintain after earthwork settlement occurred. Therefore, the management and control of embankment and foundation settlement is very important for the successful concrete track construction. We expect that the main part of the settlement of the concrete track is the one of embankment and foundation supporting it. Settlements vulnerable to the concrete track among the causes of lots of settlements are primary consolidation and secondary compression settlement of foundation, creep settlement of embankment, settlement caused by train load, and unequal settlement resulting from the difference of embankment material and construction process. This paper investigated the settlement causes to make badly effects on the concrete track and also evaluated the settlement with field tests and numerical analysis.