• Journal of the Korean Geosynthetics Society
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• v.21 no.1
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• pp.23-32
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• 2022

This study is conducted to minimize the problems caused by the difference between the settlement and settlement time of the one-dimensional consolidation analysis by the Terzaghi's consolidation theory, which is generally used in domestic soft soil design, from the settlement and settlement time measured at the field site. Consolidation-time factor considering the field site characteristics can be determined using the relationship among the degree of consolidation, settlement time, and time factor, the time-settlement curve measured at the field is reverse- analysis using a numerical-analysis technique to reproduce the same consolidation behavior as in the field. Time-settlement and time-excessive pore water pressure data when the same consolidation behavior as the site is reproduced Consolidation-time factor of the soil of Songsan Green City by settlement and excess pore water pressure was calculated using the settlement and excess pore water pressure for each settlement time. If the results of this study use the Terzaghi consolidation-time factor, which does not consider the consolidation characteristics of the soft ground target area, it is difficult to determine the end time of the soft ground during construction. It is necessary to use the established settlement-time factor.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4A
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• pp.549-564
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• 2008

In this paper, the plastic settlement of mortar is analyzed on the basis of the small strain consolidation theory, and the validity of the approach is verified through the comparison with experimental data. First, the amount of settlement caused by self-weight of bulk mortar is measured using a non-contact laser measurement device and the estimation of material parameters related to the settlement of mortar is followed. In advance, another experiment is also performed on mortar with embedded reinforcement to measure the settlement distribution, and the influence of mixture proportions and cover depth on unequal settlement is analyzed. Finally, correlation studies between experimental data and settlement distribution obtained by consolidation analysis represents that the application of consolidation theory to the analysis of plastic settlement of mortar is reasonable.

• Journal of the Korean Geotechnical Society
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• v.24 no.9
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• pp.33-40
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• 2008

This paper describes the performance of ground improvement project using prefabricated vertical drains of condition, in which approximately 10m dredged fill overlies original soft foundation layer in the coastal area composed of soft marine clay with high water content and high compressibility. From field monitoring results, excessive ground settlement compared with predicted settlement in design stage developed during the following one year. In order to predict the final consolidation behavior, recalculation of consolidation settlements and back analysis using observed settlements were conducted. Field monitoring results of surface settlements were evaluated, and then corrected because large shear deformation occurred by construction events in the early stages of consolidation. To predict the consolidation behavior, material functions and in-situ conditions from laboratory consolidation test were re-analyzed. Using these results, height of additional embankment is estimated to satisfy residual settlement limit and maintain an adequate ground elevation. The recalculated time-settlement curve has been compared with field monitoring results after additional surcharge was applied. It might be used for verification of recalculated results.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6C
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• pp.349-358
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• 2008

In performing the reliability analysis for predicting the settlement with time of alluvial clay layer at Kobe airport, the uncertainties of geotechnical properties were examined based on the stochastic and probabilistic theory. By using Terzaghi's consolidation theory as the objective function, the failure probability was normalized based on AFOSM method. As the result of reliability analysis, the occurrence probabilities for the cases of the target settlement of ${\pm}10%,\;{\pm}25%$ of the total settlement from the deterministic analysis were 30~50%, 60%~90%, respectively. Considering that the variation coefficients of input variable are almost similar as those of past researches, the acceptable error range of the total settlement would be expected in the range of 10% of the predicted total settlement. As the result of sensitivity analysis, the factors which affect significantly on the settlement analysis were the uncertainties of the compression coefficient Cc, the pre-consolidation stress Pc, and the prediction model employed. Accordingly, it is very important for the reliable prediction with high reliability to obtain reliable soil properties such as Cc and Pc by performing laboratory tests in which the in-situ stress and strain conditions are properly simulated.

• 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.

• Journal of the Korean Geotechnical Society
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• v.23 no.6
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• pp.85-95
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• 2007

In this study, in order to propose the prediction method of the residual settlement of clayey ground improved by vertical drains, a series of numerical analyses for a model ground were carried out using the elasto-viscous consolidation model. And the effects of ground improvement conditions of the ratio of effective radii $(r_e/r_w)$, consolidation pressure $({\Delta}p)$ on normally consolidated state, and the OCR (overconsolidation ratio) on overconsolidated state to reduce the residual settlement in three-dimensional consolidation by vertical drains were investigated by performing a series of numerical analyses. Furthermore, based on the results of a series of numerical analyses for the model ground, the predicting method of the residual settlement of clayey ground with vertical drains and the determination method of the value of OCR required to control the residual settlement within an acceptable value are proposed.

• Journal of the Korean GEO-environmental Society
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• v.9 no.5
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• pp.15-20
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• 2008

Compressibility of the marine clay was mainly studied velocity of consolidation and numerical analysis by this time but studies of reevaluated from the field measurement data was a little. For last three years, areal fills and extensive field instrumentations including settlement and pore water pressure were performed in the site of the Youngsan River estuary site, South Korea. From the settlement data, field consolidation curves for sub-layers were reconstructed. Effective surcharge loads during the staged loadings were calculated using the fill heights and the excess pore water pressures in the ground. In the numerical analysis (PLAXIS), prefabricated vertical drains were also simulated. Laboratory, field, and numerical analysis showed good agreements in compressibility. Due to different conditions and limitations of the clay was the same range of the oedometer tests.

• Journal of the Korean Geosynthetics Society
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• v.13 no.4
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• pp.87-96
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• 2014

In this paper, reliability analysis was done on the characteristics of consolidation and settlement for the inner temporary dike where a weak ground improvement construction was applied. When the consolidation analysis on the foundation ground was done, the following conclusions were obtained by conducting the stability analysis on the effect of space of drains, the effect of consolidation time, and the residual settlement and differential settlement. When construction was done with a drain space which satisfied 95% probability of reaching a target consolidation in each divided area, the occurrence of a residual settlement was within the range, which did not exceed 10cm. It was shown that there was almost no possibility of the occurrence of differential settlement, which was above the permissible differential settlement slope.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5C
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• pp.273-282
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• 2008

A series of analytical formula to compute settlements accounting for possible variations of initial effective stresses were derived. The comparison of computed values from conventional and newly-derived equations shows that computed settlements via the conventional equation unrealistically vary with the chosen number of layers in a clay stratum and also are 45~100% less than the value obtained from the newly-derived equation with exact mathematical integration.

• Computational Structural Engineering
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• v.10 no.4
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• pp.327-336
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• 1997

When a structure is built on the consolidation ground, the instant elastic deflection occures according to the characteristics of the ground and the load on it. And the corresponding contact pressure is established. But, as time passes, the secondary consolidating deflection is added to the instant elastic deflection, the upper structure, due to its flexural rigidity, resist to the additional curvature. So the variation of the contact pressure occurs. And this new contact pressure exerts influence on the consolidation form again. The new consolidation form exerts influence on the contact pressure in return. This kind of interaction continues till all the consolidation of the ground is finished. So the consolidation problem can not be definded as the linear problem. This paper intends to scheme an approximate iteration method to analyse this non-linear interaction problem between the upper structure and the lower consolidation ground which supports the former.