• Title/Summary/Keyword: Mikasa's consolidation theory

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Estimation of Consolidation Period for Dredged Soil by Mikasa Theory (Mikasa 압밀이론에 의한 준설토지반의 압밀기간 산정에 관한 연구)

  • 주재우;정규향;조진구
    • Journal of the Korean Geotechnical Society
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    • v.19 no.6
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    • pp.299-306
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    • 2003
  • Dredged soil experiences large settlement during consolidation because of its high water contents. Large settlement alters the thickness of the consolidation layer greatly with time. However, the consolidation theory proposed by Terzaghi assumes the thickness of the consolidation layer to stay constant. Mikasa has developed a more rational theory considering the change of thickness of consolidation layer but it is not well applied at the site. In this study consolidation tests have been performed using Rowe cell for the four dredged clay samples with a water content of 100%, 120%, 133% and 150%. From the test results compression index characteristics and coefficient of consolidation characteristics have been investigated. Coefficients of consolidation obtained by Terzaghi's and Mikasa's theories, have been evaluated and compared with each other. When Mikasa theory is applied in the field design, the period to reach the required degree of consolidation has been reduced compared with the result by Terzaghi theory because the time factor $T_{v}$ by Mikasa theory decreases with increasing of final strain of consolidation layer, Calculation method consolidation time by Mikasa theory was concisely explained for its practical use.e.

A Study on the Self-Weight Consolidation Procedure of Very Soft Ground Reclaimed by Dredging Clayey Soil (연약한 준설 매립 점성토지반의 자중압밀 과정에 관한 연구)

  • 김형주;오근엽
    • Journal of the Korean Geotechnical Society
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    • v.15 no.2
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    • pp.129-138
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    • 1999
  • This study is performed for the development of a field monitoring and test technique both of self-weight and hydraulic consolidation by which the soil parameters of dredge-reclaimed clay can be obtained effectively. The field monitoring development and tests mentioned above make it possible to reproduce the process of the self-weight consolidation from settling to reclaimed soft ground. The experimental research is mainly focussed on the characteristics of self-weight consolidation of dredged clayey soil. And theoretical study has pointed out the limits in the application of Terzaghi's one dimensional consolidation theory in interpreting reclaimed clayey ground. Furthermore, a finite difference analysis has been made on the basis of Mikasa s self-weight consolidation theory which takes the problems of Terzaghi's theory into consideration. The relationships between specific volume, effective stress, and the coefficient of permeability of Kunsan reclaimed clayey soil have been obtained by laboratory tests. On the other hand, through the field monitoring, pore pressure, total pressure, and water levels have been measured after pouring. The results of these experiments have been analyzed, and compared with those from Terzaghi's method and the finite difference analysis of Mikasa's self-weight consolidation theory. In conclusion, the measured settlements is comparatively consistent with Mikasa's self-weight consolidation theory rather than Terzaghi's consolidation theory.

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Consolidation Characteristics of Dredged Mixed Soil with Inserted Materials (혼입재료에 따른 준설 매립 혼합토의 압밀 특성)

  • Yoon Hyun-Suk;Lee Ki-Ho;Park Jun-Boum;Kim Jae-Young
    • Journal of the Korean Geotechnical Society
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    • v.21 no.4
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    • pp.13-20
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    • 2005
  • In this study, consolidation test and numerical analysis were performed with the aim of investigating the characteristics of consolidation behavior of mixed soil with the amount and particle shape of inserted materials. Mixed soil was made up of matrix (dredged clay) and inserted material (crashed oyster shell and/or sand). The concept of stress share ratio was introduced to evaluate the consolidation characteristics of mixed soils. And the finite differential numerical analysis was carried out by applying the Mikasa's consolidation theory. From the results of experiments and numerical analysis, it was verified that mixed soil consolidation behavior is affected by changes in inserted material. When a similar amount of granular material was inserted, the compressibility of the clay matrix of oyster shell mixed soil was smaller than that of sand mixed soil.

A Program Development for Prediction of Negative Skin Friction on Piles by Consolidation Settlement (압밀침하를 고려한 말뚝의 부마찰력 예측 프로그램 개발)

  • Kim, Hyeong-Joo;Mission, Jose Leo C.
    • Journal of the Korean Geotechnical Society
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    • v.25 no.9
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    • pp.5-17
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    • 2009
  • The microcomputer program PileNSF (Pile Negative Skin Friction) is developed by the authors in a graphical user interface (GUI) environment using $MATLAB^{(R)}$ for predicting the bearing capacity of a pile embedded in a consolidating ground by surcharge loading. The proposed method extends the one-dimensional soil-pile model based on the nonlinear load transfer method in OpenSees to perform an advanced one-dimensional consolidation settlement analysis based on finite strain. The developed program has significant features of incorporating Mikasa's finite strain consolidation theory that accounts for reduction in the thickness of the clay layer as well as the change of the soil-pile interface length during the progress of consolidation. In addition, the consolidating situation of the ground by surcharge filling after the time of pile installation can also be considered in the analysis. The program analysis by the presented method has been verified and validated with several case studies of long-term test on single piles subjected to negative skin friction. Predicted results of negative skin friction (downdrag and dragload) as a result of long from consolidation settlement are shown to be in good agreement with measured and observed case data.