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Investigation of Stiffness Characteristics of Subgrade Soils under Tracks Based on Stress and Strain Levels

응력 및 변형률 수준을 고려한 궤도 흙노반의 변형계수 특성 분석

  • Lim, Yujin (Department of Civil, Env. and Railroad Engineering Paichai University) ;
  • Kim, DaeSung (R&D Team, ENG Center National Forestry Cooperatives Federation) ;
  • Cho, Hojin (Department of Civil, Env. and Railroad Engineering Paichai University) ;
  • Sagong, Myoung (New Transportation Systems Research Center, Korea Railroad Research Institute)
  • Received : 2013.06.17
  • Accepted : 2013.08.12
  • Published : 2013.10.31

Abstract

In this study, the so-called repeated plate load bearing test (RPBT) used to get $E_{v2}$ values in order to check the degree of compaction of subgrade, and to get design parameters for determining the thickness of the trackbed foundation, is investigated. The test procedure of the RPBT method is scrutinized in detail. $E_{v2}$ values obtained from the field were verified in order to check the reliability of the test data. The $E_{v2}$ values obtained from high-speed rail construction sites were compared to converted modulus values obtained from resonant column (RC) test results. For these tests, medium-size samples composed of the same soils from the field were used after analyzing stress and strain levels existing in the soil below the repeated loading plates. Finite element analyses, using the PLAXIS and ABAQUS programs, were performed in order to investigate the impact of the strain influence coefficient. This was done by getting newly computed $I_z$ to get the precise strain level predicted on the subgrade surface in the full track structure; under wheel loading. It was verified that it is necessary to use precise loading steps to construct nonlinear load-settlement curves from RPBT in order to get correct $E_{v2}$ values at the proper strain levels.

Acknowledgement

Supported by : 한국연구재단

References

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