• Journal of the Korean Society for Railway
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• v.12 no.5
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• pp.800-805
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• 2009

This paper proposes the track system with twin block sleeper for a LIM type maglev railroad. Because a LIM type maglev railroad is expected to be constructed in inner city, social costs can be required under construction. Accordingly, superstructure using precast plate was adopted and twin block sleeper which can be constructed together with precast plate was developed to reduce the construction period. To examine the structural safety of the proposed track system with twin block sleeper, the finite element analyses and the laboratory experiments were performed. Also, the workability of the proposed track system was investigated through the construction simulation test and construction experience in test bed.

• Journal of the Korean Society for Railway
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• v.9 no.1 s.32
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• pp.69-75
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• 2006

In this study, Several types of geotextile was used on the selected track-bed. The use of geotextile prove a economical and efficientmean to prevent the problem of mud-pumping and settlement. Field testing sections from Mock-haeng to Dong-ryang in the Chungbuk lines in Korea were selected to investigate in current condition the of track and roadbed. This testing site was divided into 5 sections. In the four sections, different types of geotextiles were installed. In order to estimate for performance of the reinforced section with geotextiles on the soft ground, four different geotextiles were installed and compared with no reinforced section. Also, after the installation, mud-pumping, settlement of elastic or plastic sleeper, failure of track, wheel-loads, and earth pressures were investigated. The following is the summaries from the field tests. As a conclusion, According to naked eyes investigation, mud pumping didn't happen at reinforced sections, but no reinforced section was happen to a top of track for 6 months. And Elastic displacements at the reinforced and no reinforced section were about $30.7\%\;and\;73.8\%,$ respectively. Also, It was found that plastic displacement in reinforced section was retrained about $50\%$ more than that in no reinforced section.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1542-1549
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• 2011

The Transitional zone between bridge abutment and earthwork is one of the representative vulnerable zones in railway where differential settlements may take place due to the different supportive stiffness. Although transitional zones are managed with stricter standards than those of the other earthwork zones either in the design and construction stages, it is very difficult to prevent differential settlement perfectly. A three-dimensional numerical analyses were performed by applying train moving load in this study. The analytical model including abutments and earthwork zones was constituted with rail, sleepers, track concrete layer (TCL), hydraulic stabilized base (HSB), reinforced road bed, and road bed using railway and road base structure. The clamp connecting the rail and sleeper were also modeled as the element with spring coefficient. The train wheel is modeled in the actual size and moved on the rail with 300 km/hr speed. The deformation characteristics at each point of the rail and the ground were considered in detail when moving the train wheel. The analysis results were compared with those from the two-dimensional analysis without considering moving load. The research results show that displacement and stress were greater in the three-dimensional analysis than in other analyses, and the three-dimensional analysis with moving load should be performed to evaluate railway performance.

• The Journal of the Convergence on Culture Technology
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• v.10 no.3
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• pp.833-838
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• 2024

The urban railway sleeper floating track(STEDEF) is a structure that structurally separates the sleepers and the concrete bed using sleeper boots and resilience pads to reduce vibration transmitted to the concrete bed. Recently, the resilience pads of sleeper floating tracks that have been in use for more than 20 years are deteriorating. Accordingly, in order to evaluate the performance of the resilience pad, a static spring stiffness test is being performed after extracting the resilience pad. This evaluation technique is performed after replacing the resilience pad in use. However, the track natural frequency can change depending on the resilience pad spring stiffness and the uplift and subsidence of the concrete bed. In this study, modal testing technique was used to evaluate the track natural frequency. For this purpose, the sleeper boots material, resilience pad spring stiffness, and track natural frequency according to concrete bed uplift and subsidence were measured using modal tests at a laboratory scale. It was analyzed that the natural frequency of the sleeper floating track was directly affected by changes in the spring stiffness of the resilience pad. In addition, the change in natural frequency due to the uplift and subsidence of the concrete bed was also found to be large. Therefore, it is believed that the modal test technique presented in this study can be used to evaluate the resilience pad deterioration and voided sleepers.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.04a
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• pp.433-440
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• 1998

For many decades, railroad technology was used to set up tracks with jointed rails and lengths in accordance with rolling and handling technology. The joints lead to drawbacks in the track and in controlling rising maintenance costs. So, railroad engineers became interested in eliminating joints to increase loads, speeds and improvements in rolling, welding, and fastening technology. Continuous welded rail(CWR) track has many advantages over the conventional jointed-rail track. In the case of the elimination of rail joints, it may cause the track to be suddenly and laterally buckled by thermal forces and vehicle load. Thermal forces are caused by an increase in the temperature of railway track. For many years, many analytical and experimental investigations have been conducted to improve the safety of CWR track by various research center in many country. In this paper, CWR track model and CWRB program is developed for buckling analysis using finite element method(FEM). The finite element discretization is used for a rail element with a total of 14 degrees of freedom. The stiffness of the fasteners, tie, and ballast bed is included by a set of spring elements. The investigation on the buckling modes and temperature of CWR track is presented in this paper

• International Journal of Railway
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• v.9 no.1
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• pp.15-20
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• 2016

An approach section on an abutment is located between the soil embankment and the structure, which may cause an uneven surface due to different settlement between the abutment and the soil embankment. This study proposes a new type of wall which separates the abutment from the backfill material using mechanically stabilized wall. A new type of keystone which incorporates geotube and wire mesh is proposed and evaluated. Numerical analyses were performed to investigate the applicability of the proposed keystone type, which incorporates Geosynthetic. The maximum horizontal displacements along GRS wall faces, settlements at the top of pavement and track bed, and tensile forces applied on geotextiles under traffic loads were investigated. The results of the numerical analysis showed that the proposed wall can be used for highway and high-speed railway abutment.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.734-743
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• 2005

In this study, geotextiles was applied on the selected track-bed, which is relatively economical and efficient way to prevent the problem of mud-pumping and settlement. Field testing sections from Mock-haeng to Dong-ryang in the Chung-La lines in Korea were selected to investigate the state of track and roadbed. And three places were chosen among 1,700 spots where mud-pumping was frequently occurred and maintenance required. At the curved section with radius of 500m between Mock-haeng and Dong-ryang, we divided this testing site into 5 section and 4 different types of geotextile were installed and left the last section with no reinforcement. Total length of the test site was 200m and individual length of each site was 40 m. In order to understand the state and the strength of prepared roadbed, stiffness and physical properties of the roadbed soil were evaluated and analyzed. Also, after the installation, mud-pumping, settlement of elastic or plastic sleeper, failure of track, wheel-loads, lateral force and earth pressures were investigated.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1546-1553
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• 2005

In this study, geotextiles was applied on the selected track-bed, which is relatively economical and efficient way to prevent the problem of mud-pumping and settlement. Field testing sections from Mock-haeng to Dong-ryang in the Chung-buk lines in Korea were selected to investigate the state of track and roadbed. And three places were chosen among 1,700 spots where mud-pumping was frequently occurred and maintenance required. At the curved section with radius of 500m between Mock-haeng and Dong-ryang, we divided this testing site into 5 section and 4 different types of geotextile were installed and left the last section with no reinforcement. Total length of the test site was 200m and individual length of each site was 40 m. In order to understand the state and the strength of prepared roadbed, stiffness and physical properties of the roadbed soil were evaluated and analyzed. Also, after the installation, mud-pumping, settlement of elastic or plastic sleeper, failure of track, wheel-loads, lateral force and earth pressures were investigated.

• Proceedings of the KSR Conference
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• 2001.10a
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• pp.481-487
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• 2001

In this study, the relation between cant deficiency(C＇) and rail wear in Seoul Metro Line 5 with STEDEF track structure(concrete bed) is studied. As a result, it is found that cant deficiency have a direct influence on rail wear, and under the condition that other negative effects are neglected, the cant deficiency in Metro Lines is demanded to set as little as possible.

• Journal of the Korean Society for Railway
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• v.18 no.5
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• pp.466-470
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• 2015

In this study, Fenton oxidation was applied to railroad track ballasts contaminated with small amounts of oil. In order to perform the experiment on Fenton oxidation, petroleum contaminated ballast was collected from the railroad track and experiments on major factors of the remediation process were implemented in the laboratory. Then, the feasibility of insitu Fenton oxidation was investigated for the railroad track that was partially contaminated with oil. As a result, the residual TPH concentration of ballast was reduced to about 1,000 mg/kg-ballast in laboratory experiments using 0.1 mol Fe/L $H_2O_2$. Due to the drainage structure of the track bed, a considerable amount of $H_2O_2$ was released below the ballast without the sufficient reaction with the contaminated ballast; therefore, additional studies are necessary for the effective field application of Fenton oxidation.