• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.109-116
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• 1999

This study is to make clear for the characteristics of radial drainage consolidation/permeability At the result of the radial drainage consolidation / permeability test, the permeability of outflow drainage condition is higher than Inflow drainage condition and the time for the end of consolidation, outflow drainage condition is shorter than inflow drainage condition. So drainage area ratio test and control of hydraulic gradient test are carry out to analysis this result. Finally, compared with the characteristics on the condition of inflow and outflow permeability and consolidation.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.685-692
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• 2000

Vertical drain used improvement soft clay is made of not only decreasing construction time but also increasing the ground strength during some decades. As, it is applied to improvement soft clay with vertical drain, it is designed by the result that is caused by oedemeter test ignored anisotropic of the ground related to consolidation conditions. When we are expected consolidation conditions, the most important factors is soil of compaction and water permeability. Above all, anisotropic of the ground permeability show the results which differ between vertical and radial drainage. Recently, We study for radial consolidation coefficient and permeability coefficient that utilized Rowe Cell Consolidation and permeability tester but, it dont use well because of not only a supply lack also difficulty of test. The paper experimented with searching anisotropic of the ground so there are Rowe Cell test, standard consolidation tester and modified standard consolidation test that have pohang's soft clay ground. Therefore, we find anisotropic of the ground and a tester of easy use more than before. We made a comparison test result between the devised tester and Rowe Cell tester, Also, we learned average degree of consolidation for partial penetrating vertical drains. We were found relations as effective stress-void and effective stress-permeability coefficient through those tests.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.725-732
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• 2003

It was achieved that Rowecell test for this undisturbed sample was picked by Block sampler($\phi$:250mm, L:500mm) and hydraulic piston sampler($\phi$:76mm, L:850mm) in the marine clay of YONGYUDO and YEONGJONGDO in this research. Ratio of coefficient of consolidation was analyzed through comparison with C$\_$h/ by CPTu and C$\_$v/ and C$\_$h/ by existent consolidation test. According to analysis, coefficient of consolidation of block sample is fairly greater than coefficient of consolidation of piston sample. And the bigger diameter of undisturbed sample, sample disturbance could know decreasing. Coefficient of consolidation by Rowecell test measured more greatly than coefficient of consolidation by existent consolidation test. Rowecell test could know decreasing consolidation rate because of smear effect by Mandrel injection. Also, C$\_$h/ by CPTu shows deviation by each analysis method, selection of suitable analysis method judged by important leading in the coefficient of consolidation.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.495-508
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• 2010

Vertical drains are commonly used to accelerate the consolidation process of soft soils, such as dredged materials. The installation of vertical drain provides a radial drainage path to water in the deposit soil in addition to the vertical direction. An estimation of time rate of settlement is considerably complicated when vertical drains are installed to enhance consolidation process of dredged material because the vertical drains are commonly installed before self-weight consolidation is ceased. In this paper, the vertical drain theory developed by Barron(1948) is applied to analyze the non-linear consolidation behavior considering radial drainage. The overall average degree of self-weight consolidation of the dredged soil under the condition that the water is drained in both radial and vertical directions is estimated using the Carillo(1942) formula. In addition, the Morris(2002) theory and the one-dimensional non-linear finite strain numerical model, PSDDF, are applied to analyze the self-weight consolidation in case of only the vertical drainage is considered. The new analysis approach proposed herein can simulate properly the time rate of the self-weight consolidation of dredged materials that is facilitated with vertical drains.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.147-157
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• 2002

In this paper, the testing cell and the related theory far the interpretation of constant rate of strain (CRS) consolidation test results in case of radial drainage were developed. The proposed method makes it possible to evaluate consolidation characteristics of clayey soil rapidly and accurately. To investigate the application of the developed testing device and theory, CRS consolidation tests and incremental loading(IL) tests in radial drainage condition with remolded and undisturbed samples were performed. Comparisons of consolidation parameters from consolidation curves including coefficient of consolidation values show the applicability and the reliability of the suggested method. The experimental data were compared with additional vertical drainage CRS tests and IL tests, and then were analyzed considering the effect of the drainage direction. In addition, the effect of excess pore water pressure generated during CRS consolidation test was investigated.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1C
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• pp.9-17
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• 2008

In this research, an analytical solution for the coefficient of permeability of soils during consolidation is suggested. The pore pressure and the flow rate measurements at different locations during consolidation are utilized. The void ratio and volume compressibility of soils under consolidation are also estimated. A large consolidation testing device, possible in both vertical and radial drainage is designed and manufactured. And consolidation test with kaolinite soils were performed under radially inward drainage direction. Pore pressures in varying radial distances and flow rate with time were measured as well as vertical deformations. From the test results, the changes of permeability, volume compressibility and void ratio under consolidation and their spatial variations are estimated. Thus the proposed solution is verified by comparing with the experimentally estimated test results. In addition, it is confirmed that permeability, void ratio and volume compressibility decrease as consolidation and loading steps progress. Also, these soil characteristics increase with radial distant from drainage boundary, where lowest values observed, and slightly decrease as approaching undrained boundary.

• Journal of the Korean Geotechnical Society
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• v.26 no.11
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• pp.17-28
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• 2010

Vertical drains are commonly used to accelerate the consolidation process of soft soils, such as dredged materials, because they additionally provide a radial drainage path in a deep soil deposit. In practice, vertical drains are commonly installed in the process of self-weight consolidation of a dredged soil deposit. The absence of an appropriate analysis tool for this situation makes it substantially difficult to estimate self-weight consolidation behavior considering both vertical and radial drainage. In this paper, a new method has been proposed to take into account both vertical and radial drainage conditions during nonlinear finite strain self-weight consolidation of dredged soil deposits. For 1-D nonlinear finite strain consolidation in the vertical direction, the Morris (2002) theory and the PSDDF analysis are adopted, respectively. On the other hand, to consider the radial drainage, Barron's vertical drain theory (1948) is used. The overall average degree of self-weight consolidation of the dredged soil is estimated using the Carillo formula (1942), in which both vertical and radial drainage are assembled together. A series of large-scale self-weight consolidation experiments being equipped with a vertical drain have been carried out to verify the analysis method proposed in this paper. The results of the new analysis method were generally in agreement with those of the experiments.

• Journal of the Korean Geotechnical Society
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• v.24 no.6
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• pp.77-84
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• 2008

The existing equations for radial consolidation cannot account for the changes of well resistance with time and cannot predict the appropriate in-situ consolidation curve. In this study, small cylinder cell tests are performed to evaluate the discharge capacity of PVD. Also, a block sample of 1.2 m in diameter and 2.0 m in height was consolidated to observe the change in the drainage capacity with time for three types of PVD. From the test results on a block sample, the drainage curves normalized with initial drainage of each PVD are similar, regardless of the PVD type and the consolidation curve, which is predicted using solutions of radial consolidation based on the discharge capacity measured in a small cylinder cell tests, significantly overestimates the degree of consolidation. The term of well resistance in the radial consolidation solution was back-calculated to fit the consolidation curve of a large block sample and it is defined as the time dependent well resistance factor, L(t). The L(t) was found to be linearly proportional to the dimensionless time factor, Th. It was also shown that the consolidation curve evaluated by using L(t) provides more accurate prediction than the existing solution.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.649-656
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• 2000

Consolidation of the ground surrounding the sand piles is delayed by well resistance and smear effect. This study is executed to understand the factors that affect the characteristics of consolidation. This was accomplished by utilizing the estimated and measured values of the soil properties through the monitoring of the ground surrounding the sand piles. When it is assumed that the horizontal coefficient is equal to the vertical coefficient of consolidation, the estimated values is exceedingly similar to the measured values. The properties of the initially disturbed soil by the sand pile installation seemed to improve through the process of consolidation with the passage of time. From the results of the analysis of the settlement measurement, the measured values occurred about 60～90% of the predicted values. Considering the initial radical compression deformation, according to the theory of cavity expansion, the difference between the two appears to be in good agreement. In this study, to understand the behavioral characteristics of the ground surrounding the sand piles requires estimation through considering the initial radial compression as well as smear effect of the soil disturbance and well resistance.

• Journal of The Korean Society of Agricultural Engineers
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• v.48 no.6
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• pp.69-77
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• 2006

In this study, the large scaled model test improved by sand drain was carried out to clarify the internal behavior of the three-dimensional consolidation under different secondary consolidation periods. From the results of model test, the void ratio in the undrained side was lager than in the drained side. In addition, the unconfined compressive strength in the long-term consolidated specimen was larger than that in the short-term consolidated one. It was also found that the unconfined compressive strength was larger in the drained side than in the undrained side. These reasons are considered to be due to the large effective stress by quick pore water pressure dissipation by the short drainage distance in the drained side. Furthermore, in order to investigate the three-dimensional consolidation behavior of clay ground improved by the vertical drain method, the numerical analysis obtained from the three-dimensional elasto-viscous consolidation theory proposed by author (2006) were compared with the test results. It was found that during the three-dimensional consolidation process not only vertical displacement but also radial displacement occurs inside the specimen.