• Title/Summary/Keyword: Deltaic clay

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Determination of OCR on the Deltaic Clay of the Nakdong River (낙동강 삼각주 점토에 대한 과압밀비의 평가)

  • 정성교;김규종;이대명;조기영
    • Journal of the Korean Geotechnical Society
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    • v.15 no.4
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    • pp.85-97
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    • 1999
  • For a deltaic clay in the mouth of the Nakdong river, OCR was investigated through methods using the results of field measurement, laboratory and field soil tests. As a result, OCRs were obtained around the range of 0.95 to 1.20 by analysis of field measurements, although they were estimated around the values of 0.4 to 0.7 by the results of conventional consolidation tests for the clay. From the dissipation test it was found out that the excess pore pressures scarcely existed in the clay deposit and then the soil was not in the underconsolidated condition. And the OCRs obtained through methods of Mayne(1991) and Cao et al(1996) using the piezocone test and of Mayne & Kemper(1988) using the cone penetration test were in good agreement with those of field measurement.

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The Properties of Pusan Clay : Magnetic Susceptibility of Deltaic sediments in Gadeok-do Area (부산점토의 특성: 가덕도 지역 조간대 퇴적물의 대자율)

  • 김성욱;김인수;이선갑;김무겸;정성교
    • Proceedings of the Korean Geotechical Society Conference
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    • 2003.03a
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    • pp.747-752
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    • 2003
  • This study was carried out to understand the stratigraphy and depositional environment of clayey soils that distributed in the Gadeok-do area, Kimhae plain (Nakdong estuary). For the study, SPT core sampling and magnetic susceptibility analysis were conducted. Soils in study area is classified into five sedimentary facies ascending order; sand/gravel. clay, sand/gravel, clay, interbedded sand and silty clay. Analysis of magnetic susceptibility for Gadeok-do clayey soil reveals that depositional process and environment can be divided into upper, middle and lower layer, and they are closely related to the sea level change since late Quaternary.

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Prediction and Field Measurement of Settlement due to Preloading at the Delta of Nakdong River (낙동강 삼각주에서 선행하중에 따른 침하예측 및 현장계측)

  • 정성교;백승훈;김규종;이대명
    • Journal of the Korean Geotechnical Society
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    • v.15 no.5
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    • pp.99-110
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    • 1999
  • Settlement and consolidation time were predicted through systematic soil investigation at the delta of Nakdong river where the preloading method was applied. Field measurements were executed with well-selected instruments. As the results of the comparison, the predicted settlement on the sand layer of about 20m thick underestimated the observed one by 20%. This underestimation was due to the effects of vibration during installation of PBD, creep, the overestimated deformation modulus, and so on. For the clay layer of about 20m in thickness under the sand layer, an ID analysis for underconsolidated soil initially overestimated the observed settlement by 240%. However, when the laboratory compression curve was reconstructed and a conventional ID analysis for NC clay was applied, the re-calculated settlement of the clay layer was relatively similar with the observed one. And the predicted consolidation time was about 45% less than the observed one, because of different influencing factors.

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