• Geomechanics and Engineering
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• v.4 no.4
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• pp.229-241
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• 2012

In this paper, utilizing void ratio-effective stress and void ratio-permeability relationships, a system of two nonlinear partial differential equations is derived to predict the consolidation characteristics of normally consolidated (NC) and overconsolidated (OC) soft clays subjected to cyclic loading. A developed feature of the coefficient of consolidation containing two key parameters is emerged from the differential equations. Effect of these parameters on the consolidation characteristics of soft clays is analytically discussed. It is shown that the ratios between the slopes of e-$log{\sigma}^{\prime}$ and e-log k lines in the NC and OC states play a major role in the consolidation process. In the companion paper, the critical assumptions made in the analytical discussion are experimentally verified and a numerical study is carried out in order to examine the proposed theory.

• Journal of The Korean Society of Agricultural Engineers
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• v.65 no.6
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• pp.51-63
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• 2023

To improve the problem that the settlement curve of the consolidation theory of Terzaghi does not match well with the actual settlement curve, we included a secondary compression settlement and analyzed it by varying the beginning point and then obtained the following results. The current methods of calculating the compression index from the  log𝜎 curve and the coefficient of consolidation from the time-dependent settlement curve for each consolidation pressure proved that the final settlement amount will be consistent after a long time, but the actual settlement amount will always be smaller than the predicted settlement amount during the settlement progress stage. The consolidation factors estimated by the curve fitting with the condition that the secondary compression begins in the second half of the primary compression showed similar values to the consolidation factors estimated by the curve fitting for the primary compression only, and the settlement curves were in better agreement throughout the compression. It showed different values, showing low validity. It can be inferred that secondary compression acts from the point when a significant portion of the excess pore water pressure is dissipated, and the loading stress begins to have more influence on the skeletal structure of the soil. Analysis results show that secondary compression begins at the range of 91 % to 98 % on the average degree of primary consolidation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.2
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• pp.123-136
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• 2004

Terzaghi's one-dimensional consolidation theory has some important assumption, which can't be applicable to predict the behavior of soft clay ground. Especially, predictions using infinitesimal strain and linear material function related with permeability can give rise to mistake in comparison with the result of real behavior in site. For this reason, Gibson et al. established a rigorous formulation for the one-dimensional nonlinear finite strain consolidation theory, which can consider non-linearity of material function. But it is difficult to apply this theory to predict the behavior of common soft clay ground with vertical drain. In this study, consolidation model which can consider the vertical and horizontal flow of a fully saturated clay layer, self-weight of soil and nonlinear characteristics of compressibility and permeability are derived. Numerical analysis scheme, which can be applied to consolidation analysis by derived consolidation model in this study was developed. The characteristics of material function were examined using laboratory testing such as standard consolidation test, Rowe-cell test and modified consolidation test.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.520-527
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• 2000

In the present study, the analytical approaches of vacuum consolidation with horizontal drains were proposed, For dissipating rapidly pore-water in hydraulic fills, vacuum consolidation method applied vacuum pressure in horizontal drains is developed. In the analytical approaches, the governing equation is based on two-dimensional finite strain consolidation theory and the boundary conditions of horizontal drains are considered in applying negative pore-water pressure occurred by vacuum pressure, Also, parametric studies to vacuum pressure and installation pattern of horizontal drains are carried out.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.467-474
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• 2000

The application of Terzaghi's theory of consolidation for analysing the settlement of multi-layered soils is not strictly valid because the theory involves an assumption that the soil is homogeneous. The settlement of stratified soils with confined aquifer can be analysed using numerical techniques whereby the governing differential equation is replaced by 2-dimensional finite difference approximations. The problems of discontinuous layer interface are very important in the algorithm and programming for the analysis of multi-layered consolidation using a numerical analysis, finite difference method(F.D.M.). Better results can be obtained by the process for discontinuous layer interface, since it can help consolidation analysis to model the actual ground The purpose of this paper provides an efficient computer algorithm based on numerical analysis using finite difference method(F.D.M) which account for multi-layered soils with confined aquifer to determine the degree of consolidation and excess pore pressures relative to time and positions more realistically.

• Journal of Industrial Technology
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• v.21 no.A
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• pp.317-327
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• 2001

For soils with high void ratios, the inverse method of utilizing results obtained from centrifuge model test was used to find the constitutive relation of effective stress - void ratio - permeability whereas conventional oedometer test and constant rate of strain consolidation test were also used to fine its relation at ranges of relatively low void ratio. Results of column test about settlement of interface and pore pressure and distribution with time were compared with numerically estimated values to confirm such a constitutive relation as obtained from the inverse method. Consolidational settlement in dredged and reclaimed ground, where the consolidation was in progress, was predicted by using the numerical technique implemented with the finite strain consolidation theory.

• Geotechnical Engineering
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• v.14 no.5
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• pp.181-190
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• 1998

One-Dimensional Nonlinear Consolidation Model(NCM) ivas developed by using an Extended Power Function Model, which could represent the compressibility of soils. A nonlinear finite element program for NCM was developed to analyze the porewater pressure dissipation and the settlement of saturated soils. Parameters used in compressibility model could be easily obtained from conventional oedometer test data. This model has been applied to Yansan-Mulgum area for the comparison with the results of CONSOL program and that of Terzaghi theory. A Good The rates of consolidation predicted by this model and CONSOL were faster than that of conventional Tergaghi theory, for they consider the nonlinear characteristics of soils. Consolidation curves of this model were located between Terzaghi and CONSOL curves. Consolidation curves near drainage boundary, where effective stress valied rapidly, seemed to reflect the variations of compressibility of sails. Consolidation curves near drainage boundary obtained from this model were composed of two parabolic curves. Intersection of the parabolic curves occurred when effective stress reached the value of preconsolidation stress. Moreover, thin model could be used to represent the effect of magnitude of applied load. whereas CONSOL and Terazghi theory could not.

• Journal of the Korean Geotechnical Society
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• v.23 no.4
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• pp.69-77
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• 2007

In this study, the consolidation behavior of clayey ground improved by vertical drain method was analyzed by the finite difference method based on the three-dimensional elasto-viscous consolidation theory, which can express the behavior of the secondary consolidation without considering the distinction of the normally consolidated and overconsolidated states. And the applicability of the elasto-viscous consolidation theory was discussed by comparing with the test results obtained from the model test of ground improved by vertical drain system. From these results, it is found that the amount of the settlement when the excess pore water pressure almost dissipated in the clay ground with vertical drains became smaller than that of the one-dimensional condition, and then the amount and rate of the residual settlement at secondary consolidation process became larger than those of the one-dimensional condition. finally, the effect of soil parameter on behavior of consolidation process was investigated by the results of a series of numerical analysis for the normalized and overconsoldiated states.

• Proceedings of the Korean Geotechical Society Conference
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• 1996.10a
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• pp.149-158
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• 1996

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.67-74
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• 1999

Self-Boring Pressuremeter Test(SBPT) is known to be the most effective in-situ test method which can reliably determine consolidation characteristics as well as deformation modules and untrained shear strength. In order to derive the coefficient of consolidation using SBPT results it is necessary to obtain the dissipation behavior from the pore pressure change with time during constant radial strain(generally 10%) and to derive the reliable time factor(Τ) from the analytical method which considers the real in-situ conditions. As previous studies on time factor are based on the assumptions of plane strain condition that the membrane of SBP is infinite, of untrained condition during the expansion of the probe and of elastic soil behavior during consolidation, these analyses can't consider the real boundary conditions and the real soil behaviour. In this study, consolidation analysis similar to real in-situ conditions including test procedure is conducted using finite element program which employs MCC model and Biot theory. Time factor considering the effects of finite membrane length, the total pressure change during consolidation and partial drainage is proposed and compared with previous results.