• Title, Summary, Keyword: roadbed acceleration

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A Study on Field Behavioral Characteristics of the Roadbed according to the Speed Increase in High-Speed Train (HEMU-430x)

  • Eum, Ki-Young;Lee, Jee-Ha;Park, Young-Kon
    • International Journal of Railway
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    • v.6 no.2
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    • pp.78-84
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    • 2013
  • This paper is about the first experiment in Korea that was conducted on speeding increase up with rail speeds at 430km/h at high speed railway of designed 350km/h. and analysis data collected on vibration accelerations of roadbed. There are barely references on roadbed behavior measurement with rail speeds more than 350 km/h in Korea as it has never been conducted the experiment on it. So the experiments were confirmed the reliability through crosschecking the figures/values from respective sensors and measuring devices after measuring EMS and ICP types. Based on the study, values of vibration acceleration were less than 12% compared with the ones that conducted while speeding up of HEMU-430X. Also, figures of HSB for concrete bed tracks were 52% against the standard. According to the results, all the performance evaluation of vibration acceleration for roadbeds in transition zones is under the standard.

Tilting Train-induced Roadbed Response on the Conventional Line (틸팅열차 주행시 기존선 흙 노반의 응답특성)

  • Koh, Tae-Hoon;Kwak, Yeon-Suk;Hwang, Seon-Keun;SaGong, Myung
    • Journal of the Korean Society for Railway
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    • v.14 no.5
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    • pp.433-441
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    • 2011
  • It is a fact that the straightening of track alignment is one of the undoubted ways to improve the train speed on conventional lines, while that requires huge investment resources. Therefore, the operation of a tilting train as well as the minimum improvement of track is suggested as an effective and economical alternative way for the speed-up of conventional lines. Since a driving mechanism of tilting train is different from those of existing trains, in order to make sure its operation safety and stability on conventional line, the performance of track and roadbed must be preferentially evaluated on the conventional line. Furthermore, it is necessary to estimate the tilting-train-induced roadbed response in detail since the roadbed settlement can lead to the track deformation and even derailment. In this research, the patterns of wheel load and lateral force were monitored and analyzed through the field tests, and the derailment coefficient and degree of wheel off-loading were calculated in order to evaluate the tilting train running safety depending on the running speeds (120km~180km) on the conventional line. Moreover, roadbed pressure, settlement and acceleration were also observed as tilting-train-induced roadbed responses in order to estimate the roadbed stability depending on the running speeds. Consequently, the measured derailment coefficient and degree of wheel off-loading were satisfied with their own required limits, and all of the roadbed responses were less than those of existing high-speed train (KTX) over an entire running speed range considered in this study. As a result of this study, the tilting train which will be operated in combination with existing trains is expected to give no adverse impact on the conventional line even with its improved running speed.

Dynamic behavior of Track/Roadbed with Loading Frequency in Concrete Track through Full Scale Model Test (실대형 실험을 이용한 가진주파수 변화에 따른 콘크리트궤도의 동적평가)

  • Choi, Chanyong;Kim, Hunki;Eum, Kiyoung;Kang, Yunsuk
    • Journal of the Korean Geosynthetics Society
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    • v.13 no.3
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    • pp.39-47
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    • 2014
  • In this study, the full scale model tests were performed with track-roadbed system such as Ho-nam high speed railway. The measured data gives good similar a roadbed pressure with equivalent depth to the Odemark's theory. In the case of earth pressures have a under 50 kPa at upper-subgrade applying 330 kN static loading. Results of cyclic loading tests did not differ significantly from those of static loading test. The elastic displacement at HSB layer has a level of 1/100 compared to the 1 mm that it was evaluation criteria for speed up of High Speed Railway. Elastic displacement at subgrade layer was measured a level of 1/175. The dynamic characteristics of track-roadbed with loading frequency level were linearly increased under 35 Hz, while the wheel loading, displacement and acceleration of roadbed were decreased loading frequency above 35 Hz.

Dynamic Analysis of Structure's Approaches through Field Tests in the Conventional Railway (현장계측을 통한 기존선 철도 구조물 접속부의 거동분석)

  • Park, Joon-Oh;Lee, Sang-Bae;Hong, Won-Pyo
    • Proceedings of the KSR Conference
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    • pp.1864-1874
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    • 2007
  • Korean trains pass many mountain areas, so the volume of structures like bridge and tunnel has large part of railway lines. Train speed-up naturally needs a straight line in railway, then structures are increasing, and the length of structure has more than 70% in Kyongbu high-speed railway. The stiffness of bridge and tunnel is higher than the soil in the roadbed in spite of dynamic difference in vibration and displacement. Differences in stiffness have more dynamic effects and increase the deformation and destruction in the track and roadbed. This influences passenger's comfort and the safety of operation, and it needs more track maintenance. This study selected tunnel with ballast track, tunnel with concrete track, and structure's approaches with short maintenance cycle in the roadbed and had track acceleration tests and track liner inspections using track master in the field. This study will measure periodically to structure's approaches which have very fast track irregularity and analyze dynamic differences and track irregularity near structure's approaches, so realize the cause of track irregularity of structure's approaches and use basic data for reasonably strengthening method of structure's approaches.

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Characteristics of Track and Train Behaviors on High-Speed Railway Bridge/Earthwork Transiton Zone (고속철도 교량/토공 접속부에서의 궤도 및 차량 거동 특성)

  • Lee, Il-Wha;Kang, Yun-Suk;Kim, Eun;Son, Ki-Jun;Park, Chan-Kyoung
    • Proceedings of the KSR Conference
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    • pp.129-134
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    • 2003
  • It is very important to pay careful attention to construction of bridge/earthwork transition zone for high-speed railway. The transition zone of the railway is the section which roadbed stiffness is suddenly varied. Differences in stiffness have dynamic effects and these increase the forces in the track and the extent of deformation. An abrupt change of stiffness across two adjacent track portions cause irregular settlement of roadbed, track irregularity, lack of girder bending moment and reduction of lateral resistance. Especially on high-speed railway, track irregularity of transition zone cause sincere effect to track stability and train safety. And so continuous maintenance is needed. To verify this effect and to improve transiton zone capacity, In situ test, track irregularity and train acceleration test were performed on high-speed railway bridge/earthwork Transiton Zone.

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A Study on Dynamic characteristics in the Ballast gravel in Gyeongbu High Speed Railway (경부고속철도 토공부의 자갈도상에 대한 진동특성 연구)

  • Park, Jun-O;Kang, Tae-Ku;Hong, Won-Pyo
    • Proceedings of the KSR Conference
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    • pp.84-90
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    • 2009
  • The gravel ballast in the ballasted track has the function to not only transfer/scatter the train loads to subgrade through rail and sleeper but also elastically support the train loads. Because track irregularities results inevitably from the repetitive train loads, the track maintenance should be undertaken for correcting them. By analyzing the track maintenance history in the Gyeongbu high speed railway, this study tries to choose the local two spots in the railway in which the repair frequencies are maximum and relative small; to analyze their dynamic characteristics as well as grade; and to compare them with maintenance history. As the dynamic characteristics of track, the vertical displacement and vibrating acceleration of sleeper as well as acceleration of ballast are measured/analyzed. Furthermore, by collecting soil and gravel on the reinforced roadbed and undertaking ballast screening test, the size distributions are compared with grade distribution standards of high speed railway.

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Numerical Analysis of the Initiation and Development of Corrugation on a Gravel Road (수치해석적 기법을 활용한 골재 도로의 콜루게이션 발생 및 진전 분석)

  • Yun, Taeyoung;Chung, Taeil;Shin, Hyu-Soung
    • International Journal of Highway Engineering
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    • v.20 no.1
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    • pp.9-18
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    • 2018
  • PURPOSES : In this research, the initiation and development of corrugation on a gravel road with certain wheel and boundary conditions were evaluated using a coupled discrete-element method (DEM) with multibody dynamics (MBD). METHODS : In this study, 665,534 particles with a 4-mm diameter were generated and compacted to build a circular roadbed track, with a depth and width of 42 mm and 50 mm, respectively. A single wheel with a 100-mm diameter, 40-mm width, and 0.157-kg mass was considered for the track. The single wheel was set to run slowly on the track with a speed of 2.5 rad/s so that the corrugation was gradually initiated and developed without losing contact between the wheel and the roadbed. Then, the shape of the track surface was monitored, and the movement of the particles in the roadbed was tracked at certain wheel-pass numbers to evaluate the overall corrugation initiation and development mechanism. RESULTS : Two types of corrugation, long wave-length and short wave-length, were observed in the circular track. It seems that the long wave-length corrugation was developed by the longitudinal movement of surface particles in the entire track, while the short wave-length corrugation was developed by shear deformation in a local section. Properties such as particle coefficients, track bulk density, and wheel mass, have significant effects on the initiation and development of long-wave corrugation. CONCLUSIONS : It was concluded that the coupled numerical method applied in this research could be effectively used to simulate the corrugation of a gravel road and to understand the mechanism that initiates and develops corrugation. To derive a comprehensive conclusion for the corrugation development under various conditions, the driver's acceleration and deceleration with various particle gradations and wheel-configuration models should be considered in the simulation.

Detailed Analysis of Ground Vibration in Subway Tunnel (지하철 터널구간에서의 지반진동 상세해석)

  • Lee il-wha;Hwang seon-keun;Joh sung-ho;Ko hak-song
    • Proceedings of the KSR Conference
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    • pp.722-725
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    • 2005
  • Recently, ground-borne noise and vibration generated by underground transit system has been recognized as an important environmental problem. This study reviews several of the improved procedures that have been used to predict ground-borne vibration. At first, ground stiffness profile is examined by SASW test which is the most reasonable surface wave test. It is very important to acquire the exact ground stiffness profile at ground response analysis. At second, the train loading to act roadbed is calculated by using the real measured phase angle data. In finite element analysis, averaged acceleration method, infinite element, Rayleigh damping and 2-dimensional wave propagation analysis is performed.

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An Experimental Study of Diminution of Ballast Track Bridges Vibration due to the Variation of Ballast Depth (도상두께 변화에 따른 유도상교량 궤도 진동저감의 실험적 연구)

  • Kwon, Soon-Jung;Lee, Sang-Bae;Hong, Cheng-Hi
    • Proceedings of the KSR Conference
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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.

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Properties of Lightweight Foamed Concrete According to the Replacement Ratio of Waste Concrete Sludge and Variation of Foam Ratio (폐콘크리트슬러지 대체율과 기포혼입률 변화에 따른 경량기포콘크리트의 특성)

  • Lee, Jung-Goo;Kim, Jae-Won;Choi, Hun-Gug;Kang, Cheol;Lee, Do-Heun;Kim, Jin-Man
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.53-56
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    • 2007
  • Recently, waste concrete emission has been increased by acceleration of urban development and the rapid growth of redevelopment projects, so recycling of waste concrete is actively progressed, But the usage is limited to a lower value added such as the roadbed material etc. To produce the high quality recycled aggregate, breaking and washing process is added to the existing process and inevitably increases the occurrence of particle, because old mortal is included in the recycled aggregate. Therefore, this study purpose is analysis the properties of lightweight foamed concrete made by waste concrete sludge which is the by-product from produce the recycled aggregate. In result, possibility of manufacture of lightweight foamed concrete which gives equal performance compared with ALC was detect(scope of density : $0.5{\sim}0.6$, scope of compressive strength : $3.5{\sim}4.0MPa$). And scope of porosity is as follow ; total porosity : $27{\sim}30%$, open porosity : $1{\sim}5%$

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