• Title, Summary, Keyword: 노반침하

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Laboratory Test for Permanent Settlement Behavior of Geo-materials used in Railway Considering Grain size distribution and Water content (입도 및 함수비 조건에 따른 철도 노반 재료의 영구침하거동 요소시험평가)

  • Lee, Sung Jin;Lee, Il Wha;Lee, Su Hyung;Eum, Ki Young
    • Journal of the Korean Society for Railway
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    • v.18 no.4
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    • pp.354-362
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    • 2015
  • Since allowable settlement of concrete slab track is about 30mm, a lot of attention must be paid to the settlement of the earthwork (reinforced trackbed, upper subgrade, under subgrade) under the concrete track. To this end, more experimental data should be accumulated through tests for these materials. In this study, we evaluate the long-term settlement of reinforced trackbed and subgrade materials using factors such as repeated loading conditions, water content, and grain size distributions in a large triaxial test and a large oedometer test. In cases in which the performance of the reinforced trackbed layer meets the design criteria, the settlement caused by train load was considerably small. But, when the water content increases in the subgrade, unexpectedly large settlement might occur for certain grain size distributions of the subgrade materials.

Study of the Long-Term Behavior Characteristics of Roadbed on Concrete Track of High-speed Railway (고속철도 콘크리트 궤도상 토공노반의 장기거동 특성 연구)

  • Choi, Chan-Yong;Jung, Jae-Hyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.4
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    • pp.8-16
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    • 2018
  • This study examined the long-term behavior of a roadbed using high-speed railway concrete track and roadbed measurement data and evaluated the long-term performance of the track and roadbed. Recently, high-speed railway track type has been adopted as a concrete slab. On the other hand, the concrete track is vulnerable to roadbed settlement. In the case of gravel tracks, it is easy to restore the original state by maintenance even if the roadbed settles. On the other hand, in the case of the concrete track, if excessive settlement of the roadbed occurs, cracks are generated continuously on the slabs and sleepers, resulting in greatly reduced usability. For this reason, it is difficult to restore the original state only by partial maintenance. In this paper, a long-term performance evaluation was carried out on a concrete track during operation by monitoring the measurement data of sensors buried from the beginning of construction for approximately 3 years after the high-speed railway opened. Performance evaluation methods include a performance evaluation of track/roadbed when the train passes, long-term track and roadbed performance evaluation, analysis of the track/roadbed effect on long-term settlement and analysis of the factors influencing long-term settlement. The trail response of KTX-Sancheon was greatest in the track/roadbed performance evaluation by train. The results of the long-term track and roadbed performance evaluation were measured within the standard values. The track and roadbed performance impact assessment with long-term settlement was strongly related to TCL settlement. The influences of the water content and groundwater level were verified by analyzing the external factors of long-term settlement. Through such a method, the stability of a track/roadbed can be secured.

Estimation of the Roadbed Settlement and Bearing Capacity According to Radius of Curve and Cant in Railroad (철도의 곡선반경 및 캔트에 따른 노반의 침하 및 지지력 산정)

  • Jeon, Sang-Soo;Eum, Gi-Young;Kim, Jae-Min
    • Journal of Korean Society of Hazard Mitigation
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    • v.7 no.1
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    • pp.29-38
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    • 2007
  • The research on the track performance and stability of the tilting-train was performed and the settlement of the roadbed was estimated as the tilting train was being operated on the rail joint under the allowable velocity subjected to the track performance and the stability of the tilting-train. Since the impact on the continuous welded rail (CWR) induced by the tilting-train loading is different from the impact on the rail joint, it needs to investigate the settlement of the roadbed beneath the CWR. In this study, when the tilting-train is being operated on the CWR under the allowable velocity subjected to the track performance and the stability of the tilting-train, the settlement and bearing capacity of the roadbed beneath the CWR have been evaluated using numerical analysis and compared with those beneath the rail joint. The numerical results show that the settlements of the roadbed beneath CWR and rail joint are amount to 71.2% and 88.8% of the allowable settlement, respectively. And the stresses are amount to 10.4% and 12.1% of the allowable bearing capacity, respectively.

Settlement characteristics of rock/soil mixture subgrade of slab track with variation of degree of saturation (포화도 변화에 따른 슬래브궤도 혼합성토 노반의 침하 특성)

  • Park, Seong-Yong;Kim, Dae-Sang
    • Proceedings of the KSR Conference
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    • pp.1506-1512
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    • 2010
  • In this study, model tests were performed to investigate the settlement characteristics of the rock/soil mixture subgrade with the many portion of mudstone due to the cyclic train loading in high-speed railway. Specially, from the tests varying initial degree of saturation, effects of increment of the degree of saturation in the subgrade due to rainfall or elevation of ground water table under cyclic train loading on the deformation characteristics were analyzed. From the results, in the low degree of saturation, settlement converged to some value. However, in the condition of degree of saturation larger than some value, settlement rapidly increased. Therefore, it was found that it is important to maintain the degree of saturation of subgrade below the specific level to prevent the settlement of subgrade.

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Numerical Analysis of the Roadbed Settlement beneath Rail Joint Induced by Tilting-Train Loading (틸팅차량 하중에 의한 레일 이음매 하부 노반침하에 대한 수치 해석적 분석)

  • Jeon, Sang-Soo;Eum, Gi-Young;Kim, Jae-Min;Jung, Du-Hwoe;Han, Sung-Dae
    • Journal of Korean Society of Hazard Mitigation
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    • v.6 no.4
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    • pp.7-14
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    • 2006
  • The tilting-train being operated in pre-existing rail road has a different running mechanism compared to currently operated trains. Therefore, it needs to investigate the evaluation of the track performance, the stability of the tilting-train in operating condition, and the stability of the roadbed. In this study, when the tilting train is operated in the rail joint with the allowable velocity limited by the track performance and the stability of the tilting-train, the settlement of the roadbed has been evaluated by using numerical analysis. The loading on the ground surface generated by the operating tilting-train generates the settlement of the roadbed. The settlement induced by the tilting-train loading has been compared to the allowable settlement and the factor of safety defined by the ratio of the allowable settlement to the settlement generated by the applied loading is evaluated.

Grouting Performance for the Reinforcement of Operating Railway Roadbed (운영 중인 철도노반 보강을 위한 그라우팅 성능)

  • Jung, Hyuk Sang;Han, Jin Kyu;Moon, Joon Shik;Yoon, Hwan Hee
    • Journal of the Korean Geoenvironmental Society
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    • v.18 no.12
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    • pp.13-23
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    • 2017
  • This paper discusses about the reinforcement materials and construction method in order to cope with roadbed settlement in operating railway. In Korea, concrete tracks have been introduced to urban railways, high-speed railways, and general railways, but some recently constructed concrete tracks have experienced roadbed settlements. Reinforcement of the railway roadbed is urgent task for safe operation of railway, but it is difficult to reinforce the roadbed and there are no case history of reinforcing railway roadbed under an operating railroad track. Therefore, in this study, the target performance level for roadbed reinforcement was determined, and infiltration and solidity injection efficiency were investigated for selected reinforcement materials. As a result of the study, it was found that the generally used reinforcement materials and methods for geotechnical works need to be improved for applying in railway roadbed reinforcement.

Cross-Sectional Imaging of Elastic Modulus for Railway Trackbed under Ballast for Identification of Potential Settlement (침하가능성 확인을 위한 자갈도상 철도노반의 탄성계수 단층영상화)

  • Joh, Sung-Ho;Hwang, Seon-Keun;Hassanul, Raja;Abd Rahman, Norinah
    • Journal of the Korean Society for Railway
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    • v.14 no.3
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    • pp.256-261
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    • 2011
  • Recently a limited section of trackbed with ballast at KTX railway were reported to have settled down and led to problems such as reduced speed and passenger discomfort. Therefore, an urgent remedy for the settled trackbed is required to recover normal operation of KTX trains. In this paper, a new technique is proposed to visualize the elastic modulus of cross sections at railway trackbeds under ballast for practical identification of potential settlement. The proposed technique is based on ICSW technique, enabling use of impact source and overcoming inherent limitations of CSW method. To verify validity and feasibility of the proposed method, the method was employed to construct cross-sectional images of elastic modulus of two railway trackbeds and compared with other tests such as SASW, PBT, DCP and portable FWD tests.

A Study on the Compaction Characteristics of Crushed Rock-soil Mixture for Railway Subgrade (암버럭-토사 혼합성토재 철도노반의 다짐특성 연구)

  • Kim, Dae-Sang;Park, Seong-Yong;Song, Jong-Woo;Kim, Soo-Il;Song, Jae-Joon
    • Journal of the Korean Society for Railway
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    • v.12 no.2
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    • pp.183-189
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    • 2009
  • The track structure of Gyungbu High Speed Railway line from Daegu to Busan is concrete track. It has a very strict specification for residual settlement because of its rigid type structural characteristics. The residual settlement of it comes from the residual settlement of the subgrade and the ground. The residual settlement of railway subgrade composed of crushed rock and soil might be major parts of total residual settlement depending on the field compaction qualities. Therefore, it is a key to minimize the residual settlement of the subgrade for a successful concrete track construction. In this paper, total 31 large scale compaction tests were performed to understand the compaction behaviors of the crushed rock-soil mixture. The test specimens were constituted with soil, crushed shale and mudstone taken from two sites under construction. The compaction tests were performed with the variations of rock types, #4 sieve passing contents, maximum particle size, and moisture contents. The influence of those factors on maximum dry unit weights of crushed rock-soil mixture was evaluated.

Development of Design Method for Reinforced Roadbed Considering Plastic Settlement for High-speed Railway (고속철도에서의 소성침하를 고려한 강화노반 설계기법 개발)

  • Choi, Chan-Yong;Choi, Won-Il;Han, Sang-Jae;Jung, Jae-Hyun
    • Journal of the Korean Geotechnical Society
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    • v.29 no.9
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    • pp.55-69
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    • 2013
  • An alternative design method of existing methods based on elastic theory the design method of roadbed considering plastic deformation of roadbed and stress-strain at roadbed materials with the cyclic loading of trains passing. The characteristics of the developed design method considering traffic load, number of cyclic loading and resilience modulus of roadbed materials can evaluate elastic strain as well as plastic settlement with allowable design criteria. The proposed design method is applied to standard roadbed section drawing of HONAM high-speed railway considering design conditions such as allowable elastic and plastic settlement, train speed, the tonnage of trains. As a result, required levels of resilience modulus model parameter ($A_E$), unconfined compressive strength, types of soil material were evaluated.