• Title/Summary/Keyword: geotechnical design

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Parametric Study for Seismic Design of Temporary Retaining Structure in a Deep Excavation by Dynamic Numerical Analysis (동적수치해석을 이용한 대심도 흙막이 가시설 내진설계 변수연구)

  • Yang, Eui-Kyu;Yu, Sang-Hwa;Kim, Dongchan;Kim, Jongkwan;Ha, Ik-Soo;Han, Jin-Tae
    • Journal of the Korean Geotechnical Society
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    • v.38 no.12
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    • pp.45-65
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    • 2022
  • In this paper, a diaphragm wall that supports soils and rock was modeled using FLAC, a finite difference analysis program, to evaluate the seismic behavior of temporary retaining structures in a deep excavation. The appropriateness of the numerical model was verified by comparing its results with those of the centrifuge test performed in a similar condition. The bending moment distribution along the diaphragm wall shows a very similar tendency, and the maximum acceleration obtained at the backfill and top of the wall shows a difference within 5%. Based on the developed model, a parametric study was conducted in various input earthquake, ground, and excavation conditions. The maximum structural forces and bending moment under earthquake loading were compared with the maximum values during excavation, from which the critical condition that requires a seismic design was roughly sorted out. The maximum bending moment of a wall that retains soil layers increased 17%. Particularly, the axial force of struts located in loose soils increased 32% under 100 years return period of an earthquake event, which strongly is estimated to require seismic design for structural safety.

Geotechnical Chsracterization of Weathered Granite Soils in Korea (한국에 분포하는 화강암 풍화토의 토질공학적 특성)

  • 이수곤
    • Geotechnical Engineering
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    • v.9 no.3
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    • pp.5-22
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    • 1993
  • A series of laboratory tests (physical and mechanical index and engineering design) were conducted on undisturbed granite soils of CW and RS weathering grades in Korea. From these testes it can be concluded that most of physical and mechanical index values are very sensitive to change in weathering grade from CW to RS. Engineering design tests indicate that the unconfined compressive strength and the shear strength parameters are significantly reduced and that the soil becomes ductile and plastic with increasing weathering and saturation. It was found that weathered granite soils have the special characteristics when water saturated: (i) they significantly lose their shear strength(especially cohesion) and unconfined compressive strength, (ii) they are fragile and their grains break down in water as observed in grain size analysis.

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