Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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Dynamic Behavior Evaluation of Pile-Supported Slab Track System by Centrifuge Model Test

원심모형 실험을 통한 궤도지지말뚝구조의 동적 거동 평가

  • Yoo, Mintaek (Railroad Structure Research Team, Korea Railroad Research Institute) ;
  • Lee, Myungjae (Railroad Structure Research Team, Korea Railroad Research Institute) ;
  • Baek, Mincheol (Advanced Test Equipment Build-up Team, Korea Railroad Research Institute) ;
  • Choo, Yun-Wook (Dept. of Civil and Env. Eng., Kongju National Univ.) ;
  • Lee, Il-Wha (Advanced Infrastructure Research Team, Korea Railroad Research Institute)
  • Received : 2018.06.05
  • Accepted : 2019.02.26
  • Published : 2019.02.28
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Abstract

Dynamic centrifuge model test was conducted to evaluate the dynamic stability of the pile-supported slab track method during dynamic railway loading and earthquake loading. The centrifuge tests were carried out for various condition of embankment height and soft ground depth. Based on test results, we found that the bending moment was increased with embankment height and decreased with soft ground depth. In addition, it was confirmed that the pile-supported slab track system could have dynamic stability for short-period seismic loading. However, in case of long-period seismic loading, such as Hachinohe earthquake, the observed maximum bending moment reached to pile cracking moment at the return period of 2,400 year earthquake. The criterion of ratio between embankment height and soft ground depth was suggested for dynamic stability of pile-supported slab track system.

철도하중 및 지진하중 재하 시 궤도지지말뚝 구조의 동적 거동 평가를 위해 동적원심모형 실험을 수행하였다. 실험의 변수는 연약지반의 깊이와 성토체의 높이로 결정하였으며, 총 4가지 경우에 대해 실험을 수행하였다. 연약지반 깊이는 실제 연약지반층에 고속철도를 부설한 호남고속철도의 익산-정읍 구간의 시추주상도를 분석하여 결정하였으며, 성토체의 높이는 일반적인 고속철도의 성토체 높이 범위의 하한 값과 상한 값으로 결정하였다. 실험 결과, 연약지반 깊이 대비 성토체 높이 비율이 높을 수록 말뚝에 작용하는 최대 휨모멘트 값이 크게 평가되었다. 또한, 실험조건 내에서 부설되는 궤도지지말뚝 구조는 단주기 지진파에 대해서는 국내 내진설계 기준의 최대 지진하중인 0.22g에 대해서까지 안전한 것으로 확인되었다. 그러나, 장주기 지진파에 대해서는 재현주기 2400년 지진인 0.22g로 가진시 말뚝의 균열 모멘트가 초과되었다. 일련의 실험결과를 바탕으로, 본 논문에 기술된 연약지반 깊이와 성토체 높이 범위 내에서 궤도지지말뚝 일반 단면에 대한 연약지반 대비 성토체 높이 비율 기준을 제시하였다.

Keywords

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Fig. 1. Pile-supported slab track system

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Fig. 2. Pile-supported slab track model (T1)

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Fig. 3. Consolidation load by pneumatic cylinder

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Fig. 4. Schematic drawing of test section (Model scale)

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Fig. 5. Input seismic wave

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Fig. 6. Acceleration time history

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Fig. 7. Acceleration at slab structure (Ofunato earthquake)

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Fig. 8. Acceleration at interface between embankment and soft ground (Ofunato earthquake)

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Fig. 9. Acceleration at slab structure (Hachinohe earthquake)

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Fig. 10. Measured bending moment along the pile depth

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Fig. 10. Measured bending moment along the pile depth (Continued)

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Fig. 11. Maximum bending moment (Ofunato earthquake)

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Fig. 12. Maximum bending moment (Hachinohe earthquake)

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Fig. 13. Point of crack moment according to ratio of embankment hight to soft ground depth when loading Ofunato seismic waves

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Fig. 14. Point of crack moment according to ratio of embankment hight to soft ground depth when loading Hachinohe seismic waves

Table 1. Conditions of test case

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Table 2. Dimensions of prototype pile and model pile

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Table 3. Basic properties of soil materials

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Table 4. Water content and unit weight measurement results of soft ground

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