• Title/Summary/Keyword: degree of consolidation

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Estimation of the Degree of Consolidation using Settlement and Excess Pore Water Pressure (침하량과 과잉간극수압을 이용한 압밀도의 추정)

  • 이달원;임성훈
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.44 no.3
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    • pp.111-121
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    • 2002
  • This study was performed to estimate the degree of consolidation using excess pore water pressure in the very soft ground. The final settlement prediction methods by Hyperbolic, Asaoka and Curve fitting methods from the measured settlement data were used to compare with the degree of consolidation estimated by excess pore water pressure. The dissipated excess pore water pressure during embankment construction and the peak excess pore water pressure on the completed embankment were used for the estimation of the degree of consolidation. After completion of embankment, it was concluded that the degree of consolidation estimated from dissipated excess pore water pressure was more reliable than that from the peak excess pore water pressure. And, the degree of consolidation estimated from the surface settlement was nearly the same as settlement of each layer. The degree of consolidation estimated from dissipated excess pore water pressure was a little larger than that from settlement.

Evaluation of the Degree of Consolidation using Settlement and Excessive Pore Water Pressure (침하량과 간극수압에 의한 압밀도의 평가(지반공학))

  • 이달원;임성훈;윤제식;김지문
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 2000.10a
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    • pp.444-450
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    • 2000
  • This study was performed to analyze the degree of consolidation by the dissipation of excessive pore water pressure and final settlement prediction methods of the very soft clay. Hyperbolic method, Asaoka method and curve fitting method were used to compute the degree of consolidation. The degree of consolidation with excessive pore water pressure were used to compute, which considered the dissipation time with embankment construction. The degree of consolidation that was obtained by the peak excessive pore water pressure was less than in the case of the dissipation excessive pore water pressure. And, the degree of consolidation by the total settlement was nearly the same value that of layer settlement. The degree of consolidation that was obtained by excessive pore water pressure was larger than in the case of the settlement.

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Feasibility study on the Evaluation of the degree of consolidation using shear waves for soft clay deposits (전단파를 이용한 연약지반의 압밀도 평가기법 적용성 연구)

  • Youn, Jun-Ung;Kim, Jong-Tae;Lee, Jin-Sun;Kim, Dong-Soo
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.03a
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    • pp.442-451
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    • 2008
  • The evaluation of field degree of consolidation on soft clays has been an important problem in geotechnical areas. Monitoring either settlements or pore water pressures has been widely applied in the filed, but occasionally they have some problems. This study addresses the suggestion and application of another method for evaluating the degree of consolidation using shear wave velocities. A research site where soft clay layers were consolidated by surcharging loads was chosen. Laboratory tests were performed to determine the relation between shear wave velocity and effective stress. Field seismic tests were conducted several times during the consolidation of the clay layers. The tests results show that the shear wave velocity increased significantly as clays consolidated. The shear wave velocities at each field stress states were derived from the laboratory results and the degree of consolidation was evaluated by comparing the shear wave velocities obtained by laboratory and field seismic methods. In most stress states, the degree of consolidation evaluated using the shear wave velocity matched well with that obtained from field settlement record, showing the potential of applying the method using shear waves in the evaluation of field degree of consolidation on soft clay deposits.

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A Study on Consolidation Analysis Solution in Deep Soft Ground Improved by Plastic Board Drain Method (PBD공법이 적용된 대심도 연약지반에 대한 압밀분석해에 관한 연구)

  • Park, Jung-Sub;Kim, Byung-Hong;Chun, Byung-Sik
    • Journal of the Korean GEO-environmental Society
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    • v.8 no.2
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    • pp.49-55
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    • 2007
  • It is very important to determine the consolidation rate of ground, depending on the progress of time in applying this vertical drain method. Various consolidation analysis solutions capable of forecasting the consolidation rate are being proposed at the moment. However, the degree of consolidation measured from site, has a considerable different from the degree of consolidation which was obtained by the analysis of vertical drain consolidation. This study aims at assessing the applicability and verfication of each consolidation analysis solution by comparing and analyzing the degree of consolidation measured in the field and the degree of consolidation based on the theoretical equation for the analysis of the consolidation of Hansbo, Onoue, Zeng and Xie used as the consolidation analysis solution before the beginning of construction, on the basis of monitored field results and site investigation data as to the deep soft ground in Busan area applied by PBD method.

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A Study on the PVDs Consolidation Degree Considering In-Situ Conditions (현장조건을 고려한 PVDs의 압밀도 산정에 관한 연구)

  • Shin, Eun-Chul;Park, Jeong-Jun;Kwon, Hyeung-Taek
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.03a
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    • pp.824-827
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    • 2006
  • The Prefabricated Vertical Drains (PVDs) method is one of the most widely used techniques to accelerate the consolidation process in-situ and hence increase its bearing capacity. In this paper, the degree of consolidation incorporated with PVDs was evaluated in O construction work site which composed with dredged soil. O Program PVD(Version 2.3) which developed by Asian Institute of Technology was used. The purpose of this analysis is efficiently to estimate the degree of consolidation by analyzing the surface settlement with time, and drainage at initial stage and final stage by using design-parameter which based on the in-situ tests and laboratory tests. This result can be compared with analysis of the degree of consolidation using Program PVD(Version 2.3) and the field observed data in the future studies.

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The Study of Evaluating The Degree of Consolidation of The Dredged and Reclaimed Soft Ground (준설매립된 연약지반의 압밀도 산정에 관한 연구)

  • Kim, Seung-Tyull;Jung, Hun-Chul;Park, Chi-Myeon;Shin, Kyung-Ha;Jung, Ki-Moon
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.10a
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    • pp.469-478
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    • 2005
  • Understanding of an accurate state of consolidation of underconsolidated clay body, like a recently dredged or reclaimed clay deposits, is one of the most difficult tasks. The estimation of the consolidation status of these clay bodies is often made by laboratory tests of numerical analyses. However these methods demonstrated crucial limitations in the accurate prediction. Therefore, the predicted degree of consolidation from various techniques is verified by actual measured field data. The degree of consolidation of clay body in the East Side Hinterland of Gwangyang Port(2nd Phase) is evaluated in this study by using various techniques such as oedometer test, CPTu, numerical analysis and piezometer tests etc. And the results are compared each other to find the most reliable prediction technique. The merit and reliability of each method is discussed in detail. It is revealed from in this study that the estimation of degree of consolidation by an actual pore water pressure measurements is the most reliable technique.

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Sensitivity Analyses of Influencing Factors on Vertical Drain with Probabilistic Method (확률론적 해석법에 의한 연직배수 영향인자 민감도 분석)

  • Yoo, Nam-Jae;Jun, Sang-Hyun;Jeong, KiI-Soo;Kim, Dong-Gun
    • Journal of Industrial Technology
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    • v.26 no.B
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    • pp.83-92
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    • 2006
  • A probabilistic analysis model. one of reliability analysis methods introducing the concept of variables, was developed to investigate the uncertainty of dominant factors influencing the degree of consolidation in the radial consolidation theories. Based on the developed probabilistic analysis model, sensitivity study of those factors was performed to find their trends of affecting the degree of consolidation in the vertical drain method. Various radial consolidation theories, proposed by Barron(1948), Hansbo(1979), Yoshikuni(1979) and Onoue(1988), were used for this parametric study with the influencing factors such as size of smear zone, reduction ratio of permeability in the smear zone, discharge capacity, permeability for horizontal flow and coefficient of consolidation for horizontal flow. As results of this sensitivity study, for the given consolidation theory, contribution of each factor to the degree of consolidation was figure out and compared to each other. For the given value of each factor, the sensitivity to the degree of consolidation in the various theories was evaluated and their applicability and limitations were assessed.

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Influence of column yielding on degree of consolidation of soft foundations improved by deep mixed columns

  • Jiang, Yan;Han, Jie;Zheng, Gang
    • Geomechanics and Engineering
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    • v.6 no.2
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    • pp.173-194
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    • 2014
  • Laboratory and field data showed that deep mixed (DM) columns accelerated the rate of consolidation of the soft foundations. Most analyses of consolidation of DM column-improved foundations so far have been based on the elastic theory. In reality, the DM columns may yield due to the stress concentration from the soft soil and its limited strength. The influence of column yielding on the degree of consolidation of the soft foundation improved by DM columns has not been well investigated. A three-dimensional mechanically and hydraulically-coupled numerical method was adopted in this study to investigate the degree of consolidation of the DM column foundation considering column yielding. A unit cell model was used, in which the soil was modeled as a linearly elastic material. For a comparison purpose, the DM column was modeled as an elastic or elastic-plastic material. This study examined the aspects of stress transfer, settlement, and degree of consolidation of the foundations without or with the consideration of the yielding of the DM column. A parametric study was conducted to investigate the influence of the column yielding on the stress concentration ratio, settlement, and average degree of consolidation of the DM column foundation. The stress concentration ratio increased and then decreased to reach a constant value with the increase of the column modulus and time. A simplified method was proposed to calculate the maximum stress concentration ratios under undrained and drained conditions considering the column yielding. The simplified method based on a composite foundation concept could conservatively estimate the consolidation settlement. An increase of the column modulus, area replacement ratio, and/or column permeability increased the rate of consolidation.

Consolidation Characteristics of Chungju Dam Deposit Soil in the Load Increment Ratio (하중증가비에 따른 충주댐 퇴적지반의 압밀 특성)

  • 이준대;오세욱
    • Journal of the Korean Society of Safety
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    • v.15 no.4
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    • pp.123-126
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    • 2000
  • This study shows consolidation properties resulted from the experiment made on changes by load increment ratio and consolidation duration of standard consolidation test using deposit soil of Chungju Dam. Though the comparison and analysis of the result turned out that void ratio by load increment ratio was unchanged greatly, the result was inclined as followes : the smaller load increment ratio is, the bigger void ratio is, while the bigger load increment ratio is the bigger settlement is. Also coefficient of consolidation is increased in inverse ratio to load increment ratio. Coefficient of permeability is increased in proportion to load increment ratio, it is not fixed changes by consolidation duration, however. Degree of consolidation is increased to load increment ratio.

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Numerical Analysis an나bout Effects of Smear Zone in Vertical Drains on Consolidation (연직배수공법의 스미어존이 압밀에 미치는 영향에 관한 수치해석)

  • Yoo, Nam-Jae;Hong, Young-Kil;Woo, Young-Min;Jun, Sang-Hyun
    • Journal of Industrial Technology
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    • v.29 no.A
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    • pp.127-134
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    • 2009
  • In this paper, an numerical approach is performed to investigate the effects of smear zone, occurred by penetrating vertical drains, on consolidation behavior of soft clay deposits. Such a numerical analysis is applied to the field condition to confirm its applicability. Parametric numerical analyses is carried out to study influencing factors such as permeability in smear zone, boundary of smear zone and discharge capacity of vertical drains on the consolidation of soil. As results of analyses, for the given conditions of soil, degree of consolidation is getting faster with increase of permeability of vertical drain. Degree of consolidation is delayed with decrease of permeability of smear zone. As the ratio of drain width to smear zone increases, the degree of consolidation decreases. Proposed values of influencing factors by previous researchers is found to be reliable from results of numerical analyses with Cam-clay model.

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