• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.475-480
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• 2000

This study was to present the method for estimating the horizontal coefficient of consolidation by using velocity method which was based on the Barren's equation. Horizontal drainage consolidation tests, including a radial drainage consolidation test, a cylindrical consolidation test, and a large soil box test, were performed to examine its validity. Using the velocity method, horizontal coefficient of consolidation was calculated and compared with lost method, √t method, Magnan & Deroy's method, Bergado's method.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.669-676
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• 2000

The estimation of consolidation rate is one of the important factors in the construction on soft clayey deposits. A number of researches are carried out to predict the consolidation behavior in field, however, most of the results show the discrepancies between the prediction and observation. This paper analyzes consolidation behavior of normally consolidated clay in K/sub o/ condition with 2-dimensional drainage by use of the numerical methods. Elastic and elastic-plastic finite element analyses are compared in terms of the dissipation of excess pore pressure. These results are also compared with Terzaghi-Rendulic's equation that is implemented by finite difference method. The consolidation time calculated by using elastic model is found to be similar to the result of Terzaghi-Rendulic's equation. The consolidation predicted by MCC model takes more time than other cases. Initial increase of excess pore pressure in radial drainage can be shown, however, this phenomenon does not have a significant effect on tile final consolidation time.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.4C
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• pp.137-144
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• 2009

In this research, the ground with smeared zone was reconstructed using the large consolidation test apparatus. And the reconstituted kaolinite samples at different locations were retrieved for the oedometer test. From the oedometer test results the permeability- void ratio-effective stress behavior was investigated. Based on the experimental analysis, spatial differences of permeability according to the drainage distance by both smear and radial drainage consolidation reduced as the consolidation proceeds and eventually disappeared in normally consolidated region. And the spatial variation of permeability by radial drainage consolidation showed larger differences in smaller extent than the spatial variation of permeability by smear.

• Journal of the Korean GEO-environmental Society
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• v.10 no.7
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• pp.143-150
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• 2009

Material functions about effective stress, permeability, coefficient of consolidation and coefficient of volume change has important role to predict consolidation velocity and settlement of soft ground. Modified oedometer for radial drainage is adapted to find out material functions on laboratory tests. Undisturbed sample for laboratory tests were taken from construction sites of industrial complexes on southern coastal area which consists of upper dredged fill and lower original clay layer. For different drainage condition in consolidation process void ratio, effective stress, permeability, coefficient of consolidation and coefficient of volume change has been assessed with results of existing standard oedometer tests. It is worthwhile to note that consolidation material functions could be expressed as regression equation by Stark (2005), heterogeneity for permeability could be assessed from these relationships.