• 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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• 2011.05a
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• pp.1222-1229
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• 2011

Railway bridges are divided into ballastless and ballast track bridges. The ballast abrasion occurs on the ballast track upon bridges more than soil roadbed because the track vibration occurs a lot in the ballast track upon bridges due to girder vibration when a train's weight is loaded onto track even though the identical ballast is used. The phenomena of mud pumping especially, which occurs when drainage is not properly secured for heavy rain, leads to the increase of maintenance work load and the decline of ride comfort. There are countermeasures such as ballast change, installation of cross-drainage for poor drainage, gutter establishment, ballast lifting methods, ballast mats and resilient sleepers laying for the mud pumping. The ballast thickness range in domestic railroad construction rule is uniformly set up according to the design speed of railroad and passing tonnage of train without considering field conditions which is considered in foreign railroad companies. The purpose of this study is to verify the effect of vibration decrease by measuring the acceleration, displacement and ride comfort of ballast track with the change of ballast thickness on the ballast track bridges and to suggest the optimal height of ballast on the Yocheon Bridge built for the test in Honam Line.

• 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.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6D
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• pp.867-874
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• 2011

The ballast abrasion occurs on the ballasted track upon bridges more than soil roadbed because the track vibration occurs a lot in the ballasted track upon bridges due to girder vibration when a train's weight is loaded onto track even though the identical ballast is used. The phenomena of mud pumping especially, which occurs when drainage is not properly secured for heavy rain, leads to the increase of maintenance work load and the decline of ride comfort. The ballast thickness range in domestic railroad construction rule is uniformly set up according to the design speed of railroad and passing tonnage of train without considering field conditions which is considered in foreign railroad companies. The purpose of this study is to verify the effect of vibration decrease by measuring the acceleration, displacement and ride comfort of ballasted track with the change of ballast thickness on the ballast tracked bridges and to suggest the optimal height of ballast on the Yocheon Bridge built for the test in Honam Line.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.974-979
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• 2004

Recently, the development of paved track is required as a Low-maintenance of conventional line. The most important factor of paved track is stability and applicability. In this method, the ballast is grouted with mortar so that the ballast can turn into a structure like slab. This method can be subdivided into the followings. One is the method with switching the ballast, and the other is without switching the ballast. The ordinary and actual states of the ballast and roadbed were investigated to evaluate the applicability of the paved track structure in this study, and various In-situ tests were applied. Non-destructive tests such as GPR, SASW, FWD were used, and bearing capacity of roadbed, depth of the ballast, and deterioration, penetration, and contamination of the ballast were focused. The result of this investigation was utilized in the selection of optimal paved track structure and data for preliminary design.

• Proceedings of the KSRS Conference
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• v.1
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• pp.483-486
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• 2006

The study describes the monitoring of the Bay of Bengal as a ballast water exchangeable sea using MODIS/Aqua-derived diffuse attenuation coefficient (K(490)) synchronized with in situ ballast water sampling and analysis along the LNG carrier's route between Japan and Qatar from 2002 to 2005. Based on the relationship between K(490) and corresponding in situ plankton cell densities, the Bay of Bengal is recognized as a ballast water exchangeable sea to meet the regulation of ballast water performance standard of International Maritime Organization (IMO). Furthermore the Bay of Bengal with more than 200m depth and more than 200 nautical mile distance from shore is extracted based on the regulation of ballast water exchange area of IMO. However, an anomalously high K(490) area is found off the coast of Sri Lanka during the northeast monsoon in 2005, which corresponds higher cell densities than the criterion set by the regulation of IMO. The phenomenon of high cell density in the Bay of Bengal seems to be related with the phytoplankton bloom during the northeast monsoon. Seasonal and annual variability of phytoplankton bloom will be investigated to establish an early routing system for avoiding the high cell density area in advance.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.4
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• pp.301-311
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• 2017

Safety operational envelope (SOE) is the area which guarantees the safety of a submarine from the accident such as jamming and flooding. The maximum safe depth is set to prevent the damage to the hull from increasing water pressure with depth. A minimum safety depth is set to prevent a submarine from the exposure above the free surface and collision against surface ship. The prediction method for the SOE in the design phase is needed to operate the submarine safely. In this paper, the modeling and calculation methods of the SOE are introduced. Main ballast tank blowing modeling and propeller force modeling are conducted to simulate the accidents and the recovery process. The SOEs are established based on the crash stop and emergency rising maneuver simulation. From the simulation results, it can be known that the emergency rising maneuver is more effective recovery action than the crash stop.

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.3
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• pp.219-226
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• 2012

The International Maritime Organization (IMO) adopted the International Convention for the Control and Management of Ships' Ballast Water and Sediments in 2004 to prevent the transfer of aquatic organisms via ballast water. Thirty-four ballast water treatment systems were granted IMO active substance basic approval, among which twenty systems were granted final approval. This paper is an in-depth consideration of the mechanism principles of the treatment systems that received active substance basic or final approval from IMO, and on the concentration of Total Residual Oxidant (TRO). The TRO maximum allowable discharge concentration was reduced by neutralization equipment, resulting with a concentration lower than 0.2 ppm. However, between various treatment systems TRO maximum allowable dosage showed large differences, ranging from 1 to 15 ppm. The discrepancies of treatment allowable dosage concentration between different treatment systems are largely due to the properties of species and water conditions such as the temperature and turbidity, rather than the characteristics of treatment systems and the type or presence of filters etc.

• Journal of the Korean Society for Railway
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• v.8 no.2
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• pp.128-136
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• 2005

The reinforcing subgrade, which first introduced Korea for the highspeed subgrade construction, has the many advantages to maintain the quality of ballast track as well as to prevent the softening of subgrade by mud-pumping. It causes the subgrade soil to spout into the ballast on many lines. Therefore, the application of reinforcing subgrade will be expected to increase in the future. This paper introduces the reinforcing subgrade as a maintenance-free technology f3r the railroad operation and the method f3r the determination of reinforcing subgrade depth. The criteria on reinforcing subgrade depths of highspeed and conventional railroad were verified from the calculation results based on an elastic analysis method.

• Journal of the Korean Society for Railway
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• v.13 no.1
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• pp.84-91
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• 2010

We built multi-purpose large triaxial testing system that can test and evaluate various geotechnical design parameters such as shear strength, deformation modulus and stress-strain behaviour for large diameter granular materials, which are the most commonly used construction materials in the railway, road embankments. The details of the built testing system and the results obtained from static triaxial test carried out for gneiss ballast material are discussed within the scope of this paper. Ballast is hardly saturated and is confined at low overburden pressure, since the depth is shallow and the permeability is very high. Herein we ascertained that the confining pressure can effectively be controlled by vacuum. The rational trend could be checked up through triaxial test results such as shear strength, deformation, and particle breakage. And the shear strength envelope could be non-linearly represented with the parent rock strength, confining pressure of the triaxial test and proper parameters.