• Journal of the Korean GEO-environmental Society
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• v.13 no.12
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• pp.35-42
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• 2012

There are many large-scale coastal region landfill and land development by loading to use territory efficiently, this regions are mostly soft clay ground. Constructing structures and road on the soft ground bring about engineering problems like ground shear fracture and a big amount of consolidation by bearing capacity. Improvement of soft soil is required to secure soil strength and settlement control. In improvement of soft soil, predict for the amount of settlement based on field surveyed reports are important element for estimating pre-loading banking height and the final point of consolidation. In this study, there is calculating theoretical settlement by analyzing field surveyed report and ground investigation to improvement of soft soil with pre-loading and vertical drain method. And present settlement prediction method reflect soil characteristics in Gimpo Hangang site by analysing prediction settlement and observational settlement during compaction using hyperbolic, ${\sqrt{s}}$, Asaoka method.

• Journal of the Korean Geotechnical Society
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• v.38 no.8
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• pp.29-37
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• 2022

A three-dimensional analysis is required to interpret the drainage behavior of an improved ground with vertical drains, and the macroelement method enables efficient interpretation considering the three-dimensional drainage effect of vertical drains under two-dimensional plane strain condition. In this study, a novel finite element analysis program was developed by applying the macroelement method to the vacuum consolidation method used in ground improvement practice. The conventional macroelement method was used to calculate the amount of drainage from the vertical drain by setting the excess porewater pressure in the drainage material to zero; however, the program developed in this study was improved to consider negative excess porewater pressure as an actual vacuum consolidation condition. To verify the performance of the program, because of a comparison with the measurement values at the site where the vacuum consolidation method was applied, results predicted by the program and field measurement data showed similar settlement behavior.

• Korean Journal of Agricultural Science
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• v.29 no.2
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• pp.53-66
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• 2002

This study was performed to evaluation the consolidation behavior of agricultural reservoir in the very soft ground. The final settlement prediction methods by Terzaghi, Hyperbolic and Asaoka methods were used to compare with the degree of consolidation estimated by exess pore water pressure. The dissipated excess pore water pressure during embankment construction and peak excess pore water pressure on the completed embankment were suggested for the estimation of the degree of consolidation. 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. The stability methods for agricultural reservoir was used to compare and analyze with various condition by limit equilibrium method.

• Journal of the Korean GEO-environmental Society
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• v.7 no.1
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• pp.67-80
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• 2006

This paper presented an application of the geotechnical hybrid-online simulation to the consolidation settlement problem of soft clay. Conventional numerical analyses have used idealized soil constitutive models obtained from the laboratory soil tests. On the other hand, in the hybrid-online simulation, soil response was directly introduced to numerical analyses from the soil element test, and, therefore, the complicated parameter estimation was not required in this method. Fundamentals of the hybrid-online simulation method and the development of the algorithm and corresponding hardware and software for the system were presented in this study. Furthermore, an incremental loading consolidation and the hydraulic conductivity test and a comparative study using the Terzagh's conventional consolidation theory were carried out for the system verification including the performance of the experimental device and source coding of software components, and the data reliability obtained from the system. In conclusion, we found that the hybrid-online consolidation simulation system could reproduce the consolidation behavior of the remolded Kaolinite specimen withoutany discrepancies.

• Journal of the Korean Geotechnical Society
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• v.15 no.1
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• pp.161-173
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• 1999

Settlement analysis based on oedometer test results with or without Skempton-Bjerrum's modification method ( widely used for practical purposes when estimating consolidation settlements of soft clay deposits) has shortcomings that it cannot simulate real stress states and deformation behaviors of soils in case that in-situ loading and deformation conditions are not 1-dimensional. In this study, the stress path method, reflecting various probable stress paths, was employed to normally - consolidated kaolinite samples by using automated triaxial testing device which can control stress paths automatically. From this experimental study, elastic, consolidation, secondary compression and pore pressure development - dissipation behaviors under various stress paths were analyzed and deformation characteristics of soft clays, which can be the basis of rational estimation of settlements, were studied. Also by comparing results of stress path tests with those of 1-dimensional consolidation tests, limitations and problems of conventional methods were clarified.

• Korean Journal of Agricultural Science
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• v.10 no.1
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• pp.110-117
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• 1983

This study was conducted to investigate the influence of load increment ratio on the secondary consolidation for the marine clay at Asan bay by the hyperbola method. The results were summarized as follow: 1. Calculated secondary consolidation by the hyperbola method was slightly less than the value of Casagrande's log t method, but the difference was very little, and the secondary consolidation could be easily calculated by the hyperbola method even if load increment ratio was small. 2. The secondary consolidation ratio was increased with the decrement of load increment ratio, and the creep phenomenon of the settlement curve occurred under the condition of small load increment ratio seemed to be caused by the secondary consolidation. 3. The secondary consolidation ratio occurred during the primary consolidation was irregular in the overconsolidated range, but it was increased with the decrement of load increment ratio in the normally consolidated range. 4. The coefficient of secondary consolidation was increased with the increment of the consolidation load, made a point of the inflection near preconsolidation. And the coefficient of secondary consolidation was decreased from consolidation load $2kg/cm^2$, showed independent of load increment ratio. 5. The coefficient of secondary consolidation was showed in proportion to compression index.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1895-1899
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• 2012

Formulation of finite difference method for analyzing consolidation were carried out. It can be seen that the differences in settlement with time obtained by FDM and Terzaghi method are diminished by fine discretization of time increment. Excess pore pressures predicted by the derived finite difference equation were same as those calculated by Olson's method. Predicted time-settlement behavior from the derived finite difference method were almost same as those calculated by Terzaghi's method and Olson's method. Analysis results obtained from the assumed multi-step time dependent loading are thought to be reasonable.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1814-1819
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• 2010

The relation constant method between OCR and normalized net cone tip resistance has been widely used to estimate OCR value in practice. In this study, the method was analyzed for the soft soils in the Bukmyun area in Changwon city and the northwestern area in Incheon city. The relation constant value was estimated in the range of 0.28~0.33 for the Bukmyun area in Changwon city and 0.49~0.6 for the northwestern area in Incheon city. The value was max. 90% larger than it from the foreign previous studies. This is not the conservative result so the previous methods should be used with great caution of determining the constant value.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.4
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• pp.1405-1410
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• 2010

The purpose of this study is to evaluate the capability of representative existing methods through which OCR of clayey soils can be predicted utilizing PCPT data. The existing methods include Schmertmann method, Chen and Mayne method using pore water pressures measured immediately behind the cone base $u_2$, Lunne et al. method, and the latest Abu-Farsakh method. The lab. and in-situ test results, conducted in Incheon port area, were used for the study. The predicted OCR values from the methods were compared with the reference values estimated from laboratory oedometer test. Lunne et al.(k=0.5) method provided relatively better result while all the prediction methods underestimated OCR.

• Geotechnical Engineering
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• v.3 no.4
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• pp.7-20
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• 1987

This study was performed to investigate the effect of time-dependent creep on the deformation analysis of multi-dimensional consolidation using the finite element method for young Sedimentary clay. It was assumed that the creep in the clay had occured during consolidation. In the analysis, the Modified cam-clay theory originated from the critical state theory was used as the constitutive equation, in which a term equivalent to the creep was supplemnted. The results of the analysis were in good agreement with the observed values in the field.