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Tomohiro OKINO, Yasushi UJITA
2012 Volume 53 Issue 2 Pages
65-69
Published: May 01, 2012
Released on J-STAGE: May 25, 2012
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It is a regretful fact that fatal accidents sometimes still occur despite ongoing efforts to reduce accident risk and ensure the safety of railways. At the Amagasaki accident in April 2005, one carbody was severely damaged due to side impact. Static and dynamic compression tests were performed to evaluate the carbody side strength using full-size partial carbodies followed by FE analyses under the same loading conditions as in the empirical tests. The numerical results obtained by FE analyses were consistent with the empirical results in terms of the load-time characteristics as well as deformation of carbodies. A method was developed to evaluate the impact deformation behavior of a carbody subject to side loads by using FE analysis.
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Hisayo DOI, Takefumi MIYAMOTO, Junichi SUZUMURA, Junichi NAKAHASHI, Hu ...
2012 Volume 53 Issue 2 Pages
70-76
Published: May 01, 2012
Released on J-STAGE: May 25, 2012
RESEARCH REPORT / TECHNICAL REPORT
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A number of flange climb derailments have occurred in sharp curves or curves with turnouts within relatively short accumulated running distances subsequent to wheel turning. This indicates that a change in the condition of the turned wheel surface might be a factor inducing flange climbing. Through several experiments and numerical simulations, the authors investigated the relationship between the running safety of a vehicle and its wheel surface condition especially in terms of wheel/rail friction. Furthermore, lubrication just after wheel turning was proposed as a countermeasure to flange climb derailments and its effectiveness and persistence were evaluated.
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Satoru HATSUKADE
2012 Volume 53 Issue 2 Pages
77-79
Published: May 01, 2012
Released on J-STAGE: May 25, 2012
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Estimating the interference current produced by railcars is necessary to ensure electromagnetic compatibility (EMC) between railway signaling systems and railcars. Although various types of signaling systems use low-frequencies such as those used for track circuits, no estimation method so far covers low-frequency return-currents on DC electric railcars. This paper proposes a new method for estimating the spectrum of low-frequency return-currents on DC electric railcars. This method only requires DC electric railcar characteristics such as train mass and starting acceleration. Measurement results presented in this paper clearly indicate the effectiveness of the developed method.
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Xiu LUO, Kimitoshi SAKAI, Masamichi SOGABE
2012 Volume 53 Issue 2 Pages
80-86
Published: May 01, 2012
Released on J-STAGE: May 25, 2012
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Since differential displacement of track surfaces caused by earthquakes strongly influences the running safety of trains, it is important to consider its effects for the seismic design of railway structures. In this paper, in order to obtain a proper seismic wavelength for the assessment of track differential displacement, the authors examined phase velocity characteristics which reflect the dispersion of Rayleigh waves, and proposed an empirical formula for calculating the wavelength suitable for track assessment based on sets of various real ground parameters. Moreover, the influence due to the wavelength and the characteristics of the ground on the angular rotation assessment of viaducts was examined.
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Kenji WATANABE, Masaru TATEYAMA
2012 Volume 53 Issue 2 Pages
87-92
Published: May 01, 2012
Released on J-STAGE: May 25, 2012
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Under current design standards, conventional retaining walls and bridge abutments are classified in the same category as retaining structures and the same seismic design procedures are therefore applied. Their dynamic response characteristics nonetheless are quite different. A series of shaking table model tests were performed therefore for this study in order to evaluate the dynamic response characteristics of each structure. The experiments revealed that external forces such as inertial force and earth pressure acting on these structures during shaking were quite different. Based on these test results, proposals were made for a new set of seismic design procedures for each structure considering the abovementioned response characteristics.
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Akihiro TOYOOKA, Yoshitaka MURONO, Yuta NOGAMI, Takayoshi NISHIMURA
2012 Volume 53 Issue 2 Pages
93-101
Published: May 01, 2012
Released on J-STAGE: May 25, 2012
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The research in this paper studies the effect of the response of upper structure and soil deformation on the overall behavior of structure through static and dynamic analyses. Several structures with pile foundations, such as bridge pier, viaduct and isolated bridge, were assumed to be constructed on a soil of good condition. The soil deposit characters were selected so that their deformations could be regarded as negligible in the design standard, whereas their shear velocity and resulting strain would change drastically with the depth. It was clarified through series of simulations that response of soils significantly affects the moment distributions of piles, regardless of the amount of response of superstructures. It consequently follows that the soil behavior should be properly considered even under good soil condition.
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Shunta NODA, Shunroku YAMAMOTO, Shinji SATO
2012 Volume 53 Issue 2 Pages
102-106
Published: May 01, 2012
Released on J-STAGE: May 25, 2012
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The Shinkansen Earthquake Early Warning system rapidly estimates earthquake parameters from a single station data. Epicenter locations in this system are estimated utilizing the Principal Component Analysis and the B-Δ method. This paper proposes new methods to improve the performance of epicenter estimation by introducing variable time windows, instead of the conventional fixed time window. It was found that the new method improved the accuracy and speed of the back-azimuth estimation by 28% and 0.25 seconds respectively. Speed of estimation of the epicentral distance was improved by approximately 1.32 seconds, compared with the conventional method.
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Osamu NUNOKAWA, Taichi KOHMA, Tomoyasu SUGIYAMA
2012 Volume 53 Issue 2 Pages
107-112
Published: May 01, 2012
Released on J-STAGE: May 25, 2012
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Rockfalls from slopes sometimes occur over railway lines. It is therefore essential to minimize rockfalls onto railway lines to maintain safe and punctual train operations. It is also necessary to evaluate the risk of rockfall from slopes considering probability and the cost of resulting damage. This paper describes a method for evaluating the risk of a rockfall incident using a risk assessment technique. This method is also described for determining priorities for investment into rockfall prevention.
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Keiji ARAKI, Toshiaki IMAI, Katsuji TANEMOTO, Minoru SUZUKI
2012 Volume 53 Issue 2 Pages
113-120
Published: May 01, 2012
Released on J-STAGE: May 25, 2012
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Anemometers for operation control are mostly installed close to railway structures. Railway structures might therefore influence anemometer wind velocity data readings. The authors investigated the influence on the wind velocity of the anemometer position around typical railway structures through wind-tunnel tests and field wind observations. In the case of single-track embankments with a height of 6.5m from the ground surface, the increase in wind velocity on the leeward side was greater than on the windward side of railway structures, for heights up to 4m above rail level, as the wind direction approaches a 90 degree angle to the longitudinal direction of the railway structure.
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