• Journal of the Korean GEO-environmental Society
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• v.13 no.5
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• pp.13-24
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• 2012

In this study, the in-situ model test has been conducted and used to estimate and analyze consolidation behavior of the ground by using the miniature test that reconstructs economically geotechnical behavior of in-situ full scale structure. To analogize the relation among effective stress, void ratio and coefficient of permeability at the self-weight consolidation stage, the low stress seepage consolidation test has been conducted and the involution function of constitutive equation had been obtained from the result of the curve fitted seepage consolidation test result. As a result of the numerical analysis that had been conducted on the representative section using a constitute equation, final settlement was similar with those of self-weight consolidation of the centrifugal model test. But, it was more or less smaller. It seems that these trends are caused by the difference between estimated values.

• Journal of the Korean Geotechnical Society
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• v.30 no.1
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• pp.103-116
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• 2014

This paper presents the results of a numerical investigation on the load carrying capacity and consolidation behavior of suction piles. Three dimensional numerical models which reflect realistic ground conditions and installation procedures including the ground-suction pile interface were adopted to conduct a parametric study on variables such as the length-diameter ratio and the loading configurations, i.e, vertical, horizontal, and combined loads. The results indicated that the load carrying capacity of a suction pile can only be realistically obtained when the interface behavior between the suction pile and the ground is correctly modeled. Also carried out was the stress-pore pressure coupled analysis to investigate the consolidation behavior of the suction pile after the application of a vertical loading. Based on the results, failure envelops and associated equations were developed, which can be used to estimate load carrying capacity of suction piles installed in similar conditions considered in this study. The results of consolidation analysis based on the stress-pore pressure coupled analysis indicate that no significant excess pore pressure and associated consolidation settlement occur for the loading configuration considered in part due to the load transfer mechanism of the suction pile.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.127-135
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• 2002

The accurate evaluation of settlement is important to every steps in the constructions involving soft soils. Relating with those constructions, especially, it has been emphasized recently that the influnce of secondary settlement is important. The ratio of $C_a/C_c$ and the surcharging tests can be applied collaboratively to predicting and reducing secondary consolidation. A series of incremental loading consolidation test and surcharging tests for undisturbed samples of Kunsan clay were performed in this study. As a result of the tests, the ratio of $C_a/C_c$ for the clay was found to be 0.0329. Also, the relationship between void ratio and $t/t_p$ was shown to be linear. Accordingly, the secondary compression index, $C_a for a long term loading had a constant value regardless of time. When the total surcharge ratio was 0.4 and the dissipation ratio of excessive porewater pressure was in the range from 80% to 100%, secondary settlement was effectively reduced for Kunsan clay.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1188-1191
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• 2009

In this study, cyclic triaxial tests were performed with the samples which were anisotropically consolidated using irregular earthquake loading to consider in-situ condition and seismic wave. The consolidation pressure ratio(K) was changed from 0.5 to 1.0. The Ofunato and Hachinohe wave are applied as irregular earthquake loading and liquefaction resistance strength was estimated from excess pore water pressure(EPWP) ratio. As results of the cyclic triaxial tests, buildup of EPWP ratio increased as K value increased. It shows, that the isotropically consolidated sands is more susceptible to liquefaction than anisotropically consolidated sands under equal conditions such as confining pressure and dynamic loading.

• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.3
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• pp.90-99
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• 1994

To investigate the undrained shear strength characteristics of marine soils with high water content, high compressibility and weak bearing capacity, a series of undrained triaxial tests with pore pressure measurements on undisturbed and disturbed Banwol marine clay in normally consolidated and overconsolidated states is carried out. The results and main conclusions of this study are summarized as follows : 1 . When the consolidation pressure is increased, the maximum deviator stress of disturbed and undistubed clay in normally consolidated state is increased. Pore pressure parameters and internal friction angle of undisturbed clay are greater than those of disturbed clay. 2. The relationship between pore pressure and axial strain of undisturbed clay in normally consolidated state can be expressed as a hyperbolic function like stress-strain relation proposed by Kondner. 3. In the pore pressure-axial strain relation of disturbed clay in normally consolidated state, failure ratio R'f is greatly deviated in the range of 0.7~0.9 proposed by Christian and Desai. 4. For overconsolided clay, when overconsolidation ratio (OCR) is increased, normalized maximum deviator stress is increased and maximum pore pressure is decreased gradually. 5. Cohesion of overconsolidated clay is greater than that of nomally consolidated clay and internal friction angle slightly is decreased. 6. Pore pressure parameter at failure (Af) of overconsolidated clay is varied with OCR, Af becomes negative values with increment in OCR

• Journal of the Korean GEO-environmental Society
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• v.2 no.3
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• pp.57-69
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• 2001

Sand pile is widely used as a ground improvement method. Although the primary purpose of constructing sand pile is accelerating consolidation, composite ground effect also can be gained by constructing sand pile. This study was accomplished to understand composite ground effect on the ground improved by sand piles which were applied as vertical drainage material when area replacement ratio was small relatively. For determining bearing capacities of origin ground and sand piles and analysing interaction between embankment and origin ground, bearing tests and earth pressure monitoring are performed. From the results, it turned out that the contribution of sand pile as a load bearing mechanism is not substantial. However, the bearing capacity of sand pile was increased to sixty percentages when compared with origin ground. The increasement of bearing capacity could be caused the change of consolidation characteristics during the process of consolidation by overburden load. Therefore, the composite ground effects depending on stiffness increasement of sand pile would be estimated as a factor decreasing consolidation settlement.

• Journal of the Korean Geotechnical Society
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• v.20 no.2
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• pp.59-66
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• 2004

Sand compaction pile (SCP)-improved ground is composite soil which consists of the SCP and the surrounding soft soil. When a surcharge load is applied to composite ground, time-dependent behaviors occur in the composite soil due to consolidation according to radial flow toward the SCP. In addition, stress transfer also takes place between the SCP and the soft soil. This paper presents the numerical results of cylindrical composite ground that was conducted to investigate smear effect on consolidation behaviors of SCP-improved ground. The results showed that the smeared zone of soft clay had a significant effect on effective stress-pore water pressure response, stress transfer mechanism and stress concentration ratio of composite ground. Amount of stress transfer between the clay and the SCP was maximum in depth of z/H=0.25, and decreased with depth. Stress concentration ratio of composite ground was not constant, but depended on consolidation process. It was also found that the value of stress concentration ratio in soft clay with smeared zone was larger than that in soft clay without smeared zone.

• Journal of the Korean GEO-environmental Society
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• v.9 no.3
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• pp.61-68
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• 2008

Side friction is often neglected in the analysis of the results of a consolidation test when the specimen has a high ratio of diameter to height. As the height of a specimen increases, however, side friction becomes important. This paper presents an investigation of the effect of side friction on consolidation test results for normally consolidated kaolinite slurry. Consolidation tests were performed to obtain settlement, pore pressure, compressibility, and hydraulic conductivity of kaolinite slurry. The compressibility relationship is corrected for side friction using a modified form of Taylor (1942) analytical solution. Numerical simulations using the CS2 piecewise-linear model are compared with settlement and excess pore pressure measurements. Experimental results show improved agreement with a modified CS2 model in which the effect of side friction is considered. The numerical and experimental results indicate that the side friction is an important factor affecting the rate of consolidation as well as the compressibility relationship for the specimen.

• Journal of the Korean Geotechnical Society
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• v.19 no.4
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• pp.7-14
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• 2003

This study has investigated the feasibility of caissons for accelerating consolidation (C.A.C.) constructed in clays with anisotropic permeability by improving the former study on C.A.C. in isotropic clays. Analytical solutions for excessive pore water pressures of two-dimensional consolidation equation and average degrees of consolidation with varying time factors have been provided by considering anisotropic permeability. With varying anisotropic permeability ratios of 5, 10, and 50, consolidation times required for reaching the average degree of consolidation of 90% for C.A.C. at the section of $\xi$=0.1 are shorter than those for conventional caissons by 8, 13, and 47 times, respectively. C.A.C. is more effective in reducing consolidation time as anisotropic permeability ratio increases. This study provides also plots for average degrees of consolidation versus the width to depth ratios of analyzed sections and permeability ratios, which will enable engineers to determine easily average consolidation settlements.

• Journal of the Korean Geotechnical Society
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• v.20 no.6
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• pp.137-150
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• 2004

Aging effect of sands showed insignificant result in comparison with that of clay, so that it has not been studied so far. But, as penetration resistance increase has been observed with the lapse of time after deposition and disturbance, aging effect of sands has been actively investigated by field tests, and recently many researchers are performing not oかy field tests but also laboratory tests on sands, so aging effects of sands have been also examined by laboratory tests. In this study, to observe the aging effect of undrained static shear behavior for Nak-Dong River sand, undrained static triaxial tests were performed with changing relative density$(D_r)$, consolidation stress ratio$(K_c)$, and consolidation time. These tests showed that modulus within elastic section increased as consolidation time increased, and in addition, phase transformation point strength$(S_{PT})$ and critical stress ratio point strength $(S_{CSR})$ also increased. But pore water pressure ratio$(u/{p_c}')$ decreased as consolidation time increased, so with this various result, aging effect of static shear for sands can be observed as well.