• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.2052-2057
• /
• 2010

In December 2006, the Ministry of Environment in Korea established the "Indoor Air Quality Management Guidelines in Public Transportation." As the items of the guideline, $CO_2$(Carbon dioxide) and PM10(Particulate matter). Therefore, the air quality inside the train is supposed to be ruled by this guideline. This study calculated the increase or decrease rate of the $CO_2$ concentration by using the data measured in accordance with flap operation. In case of flap close or open, the calculated $CO_2$ concentration variation was 6.32ppm/min. The $CO_2$ concentration prediction equation was derived from the general equation and the actual measured value are compared with the predicted $CO_2$ concentration suggested during the KyungBu high speed railway construction. The predicted value show good agreement with the measured data.

• Smart Structures and Systems
• /
• v.21 no.5
• /
• pp.549-559
• /
• 2018

The dynamic behaviors of the bridge structures have great effects on the comfortability and safety of running high-speed trains, which can also reflect the structural degradation. This paper aims to reveal the characteristics of the dynamic behaviors induced by train loadings for a combined highway and railway bridge. Monitoring-based analysis of the acceleration and dynamic displacement of the bridge girder is carried out. The effects of train loadings on the vertical acceleration of the bridge girder are analyzed; the spatial variability of the train-induced lateral girder displacement is studied; and statistical analysis has been performed for the daily extreme values of the train-induced girder deflections. It is revealed that there are great time and spatial variabilities for the acceleration induced by train loadings for the combined highway and railway cable-stayed bridge. The daily extreme values of the train-induced girder deflections can be well fitted by the general extreme value distribution.

• Tunnel and Underground Space
• /
• v.25 no.6
• /
• pp.487-495
• /
• 2015

The specification for selecting railway ballast in France is introduced in this study and the effectiveness of selection for railway ballast is studied for the case of a quarry located in northen France. The quality of railway ballast is, in general, estimated depending on the grain distribution and mainly of the resistance against abrasion. The resistance against abrasion is obtained by both Los Angeles abrasion test and Micro Deval test, which determine the ballast quality suitable whether for high speed railway or classical railway. This study analyzed the correlation between the abrasion index obtained from the abrasion tests for the aggregates sampled at three different stages among ballast production procedure at the quarry. A high correlation is determined between Los Angeles Abrasion index (LA) and Micro Deval index (MDA) and also between abrasion indices of different aggregates. Particularly, this correlation between the abrasion indices allows to estimate the quality of ballast at the final stage from the aggregates at the site in a quarry within the margin of error.

• Journal of the Korean Society for Railway
• /
• v.12 no.6
• /
• pp.829-834
• /
• 2009

A ballast-flying probabilitie is suggested for various ballast types, heighter types and underbody flow conditions as train speeds. The average speed of measured points is converted to the ballast-flying probabilities of BFPF which come from wind tunnel test data. Underbody flow fields are numerically simulated for the various conditions. The results show that the ballast-flying probability is steeply increased as train speed increased, and reaches a value of 87% at 350 km/h train speed. And the differences of probabilities among the ballast shapes are considerably high. The upper surface of heighter or tie is most probable area. Through this study, the ballast-flying Sensitivities with heighter was defined to understand the characteristics of ballast-flying probability on various conditions. And the ballast-flying probability can be reduced by the heighter.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.85-90
• /
• 2007

Aerodynamically generated noise is significant when the train speed exceeds 250km/h. Experiments were performed in order to investigate the characteristics of aerodynamic noise sources generated from exterior of the HSR-350x, especially from the inter-coach spacing. Measurements of both the inside and outside of the cabin are carried out to investigate the characteristics of the noise. Effect of the size of the gap has been investigated through an wind tunnel test and it has been found that the low frequency noise is strongly dependent on the size of gap. Also performed is an array measurement to locate different noise sources from the high-speed train. Spectral characteristics of exterior noise sources have been examined through these experiments.

• Tunnel and Underground Space
• /
• v.15 no.5 s.58
• /
• pp.359-368
• /
• 2005

In case the overburden of a tunnel is too low to adopt NATM, cut and cover method generally can be chosen as alternative. However, in tunneling some area with very low or no overburden between two mountains, the cut and cover method requires additional construction of a couple of tunnel portals and the maintenance of portal slopes until backfilling is completed. As a solution for this problem, increasing the tunnel overburden by raising the ground level can be effective. This paper presents the case study for tunneling at C240 site in Taiwan High Speed Railway(THSR) in which soil-cement filling method was used for pre-banking before tunnel excavation. Cement content of filling material was $2\~4\%$ and thickness of filling a round was $130\~250\;mm$. The stability evaluation for the soil-cement slope and concrete lining of low cover tunnel was conducted by numerical analysis.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.25 no.1
• /
• pp.7-13
• /
• 2016

With the increasing running speed of trains, new railway lines in metropolitan areas, and the rising demand for green transportations, the number of underground and tunnel sections are constantly becoming larger, and installations of overhead rigid conductor systems are becoming wider. However, domestic commercial products for overhead rigid conductors are limited to 120 km/h train speeds. In this study, to develop a high-speed (250 km/h) overhead rigid conductor, R-Bar (Rigid Bar), the electrical and mechanical stability was enhanced through the improvement of the cross sectional shape of the R-Bar; the transition structure was also designed for flexibility and natural frequency isolation. In addition, the evaluation of contact forces between a pantograph and the overhead rigid conductor system for 250 km/h train speeds was performed using dynamic analysis.

• Journal of the Korean GEO-environmental Society
• /
• v.15 no.9
• /
• pp.19-28
• /
• 2014

Recently, the proportion of long tunnel has increased for efficient use of land due to limited land area, driving convenience and high speed. RMR and Q-System of empirical methods has been mainly used for tunnel support design in domestic. Although shotcrete is the key to NATM tunnel, the related studies are insufficient. So, steel fiber reinforced shotcrete is applied to II~V grade rocks on domestic and foreign applications. And same amount of shotcrete is equally applied to tunnel roof and wall regardless of the applied rock load. Shotcrete is applied excessively rather than the original proposed value of RMR and Q-System. Thus, this study is to reevaluate the application part of plain shotcrete and steel fiber reinforced shotcrete of tunnel in Daebo granite, and to propose the reasonable application method of steel fiber reinforced shotcrete. Field test and numerical back analysis using measurements were performed to verify stability. According to results, if RMR values are the upper class in the III grade, it can be designed in accordance with upper grade. In addition, if rock condition is good as a mountain tunnel in Daebo granite, it can be applied for plain shotcrete to III grade rocks because there is also no stability problems. And although steel fiber reinforced shotcrete is applied only crown of the tunnel in IV grade rocks, it is possible to secure stability for falling rock by key-block.

• Journal of the Korean Society for Railway
• /
• v.19 no.5
• /
• pp.647-655
• /
• 2016

The construction of high speed railways and improvement projects of for conventional railways require straight railway lines of railway, which leads to an increase of bridge and tunnel construction. Transition zones in railways means that the track support stiffness is variedvaries in over short ranges. Sspecial attention is required in theose transition zones since because instability of train running in train and irregularities of track irregularities are can frequently occurred. Typical transition zones are between bridges and earthworks and between tunnels and earthworks. On In a transition zone, a bridge abutment transition zone has many problems in with various causes. In this paper, fundamental problems of bridge abutment transition zones is are analyzed to enhance the understanding about of bridge abutment transition zones. Suggestions for improving problems in the transition zones are proposed.

• Smart Structures and Systems
• /
• v.21 no.5
• /
• pp.561-569
• /
• 2018

Ground vibration is one of the most undesirable effects induced by blast operation in mountain tunnels, which could cause negative impacts on the residents living nearby and adjacent structures. The ground vibration effects can be well represented by peak particle velocity (PPV) and corner frequency ($f_c$) on the ground. In this research, the PPV and the corner frequency of the mountain surface above the large-span tunnel of the new Badaling tunnel are observed by using the microseismic monitoring technique. A total of 53 sets of monitoring results caused by the blast inside tunnel are recorded. It is found that the measured values of PPV are lower than the allowable value. The measured values of corner frequency are greater than the natural frequencies of the Great Wall, which will not produce resonant vibration of the Great Wall. The vibration effects of associated parameters on the PPV and corner frequency which include blast charge, rock mass condition, and distance from the blast point to mountain surface, are studied by regression analysis. Empirical formulas are proposed to predict the PPV and the corner frequency of the Great Wall and surface structures due to blast, which can be used to determine the suitable blast charge inside the tunnel.