• Journal of the Korean GEO-environmental Society
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• v.11 no.4
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• pp.25-31
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• 2010

The amount of dredging clay will be greatly increased by the eco-rive project and port development in Korea. Geotechnical engineers have thrown their efforts into the new ways for effective re-uses of the dredging clay such as the material for reclamation, and so on. However, very high initial water content and low strength causes unexpected difficulties in the aspect of trafficablility or time for consolidation. Therefore, the injection of cement stabilizer is used as one of ways to improve reclaimed ground. However, it also makes an argument by heavy metal from cement stabilizer. In this paper constant rate of strain consolidation test and normal consolidation test were performed to investigate behavior characteristics of the consolidation about soil-cement include lean mixed cement to reduce the environmental loads by the cement. The experimental results of consolidation characteristics about soil-cement include lean mixed cement influenced by mixing ratio. Especially it was observed that mixing ratio of 4%~6% leads not only the reduction of consolidation settlement, but time for consolidation.

• Geotechnical Engineering
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• v.12 no.1
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• pp.5-20
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• 1996

In order to accelerate the rate of consolidation settlement and to gain a required shear strength for a given soft clay deposit, the preloading technique combined with a vertical drainage system has been widely applied. In this'study, the theory of axisymmetric consolidation which considers the variation of compressibility and permeability during the conslidation process, has ben developed. A computer program named AXICON for the analysis of axisymmetric nonlinear consolidation is developed by adopting an explicit finite difference method. Smear and well resistance effects are also considered. The AXICON is capable of analyzing the consolidation behavior of multi -layered deposits and simulates time dependent loading sequence. The results of AXICON are validated with analytical solutions of Hansbo and Barron, and compared with insitu settlements and pore pressures measured in a soft clay deposit.

• Journal of the Korean Geotechnical Society
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• v.30 no.2
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• pp.53-64
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• 2014

This study sets it's face to define effects of the various loading periods in normal consolidation area on clay's compression and long-term consolidation characteristics through a laboratory test using homogeneous remolded clay. Moreover, by carrying out a long-term consolidation test which diversifies initial consolidation applicable to effective overburden loading in the various loading period. This study intended to suggest the method predicting the final settlement on the basis of loading periods by comparing and analyzing compression curve's characteristics according to loading weight of each stage and increase in loading period when carrying out the standard consolidation test. From the test results, the study shows that as of the soft clay's compression characteristics on the basis of various loading periods, preconsolidation load has a tendency to be decreased slightly as the loading period is getting more and more longer at each step after initial consolidation load puts on the remolded clay which is caused by secondary consolidation's increase in the latter part of each phase. And those effects have an weaker influence on compression index in normal consolidation area at the same time as secondary consolidation brought out quasi-overconsolidation and stabilization of clay's structure, have an influence re-compression index is increased in overconsolidation area on the other hand.

• Journal of the Korean Geosynthetics Society
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• v.23 no.1
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• pp.39-47
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• 2024

In this study, physical property tests and standard consolidation tests were conducted on the marine clay of Busan New Port and North Port, the middle and lower reaches of the Nakdong River including Gimhae and Yangsan, and Ulsan regions. The moisture content, a property unrelated to sample disturbance with small individual test errors, was used for regression analysis with the compression index, virgin compression index, consolidation coefficient, expansion index, and secondary compression index, among others. Subsequently, the correlation and accuracy were evaluated. Upon analyzing the correlation between the moisture content, void ratio, and liquid limit commonly used physical properties for calculating compression indexes, it was confirmed that the liquid limit had the lowest correlation. Through a linear regression analysis of the consolidation constants using the current moisture content in the natural state, a high correlation was demonstrated. Relationship equations were then presented to determine settlement and settlement time. This study suggests that moisture content can be utilized as an alternative for evaluating and calculating consolidation constants when examining ground settlement in sedimentary clays distributed in the Busan and Gyeongnam regions.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.3
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• pp.565-572
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• 1994

Consolidation behavior on soft clay was investigated by using one- and two-dimensional analysis based on original and modified one dimensional consolidation theory. For the analytical model, the embankment was simulated by applying single- or multi-surcharge loading to the surface of soft clay. Based on the results obtained, it was found that the predicted settlement by one dimensional consolidation theory was most of the time higher than the observed one at the mid- and especially lateral-zone of embankment. When compared with two dimensional analysis, the result of modified one dimensional consolidation analysis showed almost similar trend to the observed one. There fore even in case where proper selection of soil parameters, one dimensional consolidation theory like as modified one dimensional consolidation theory could be suggested due to its convenience.

• Geotechnical Engineering
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• v.1 no.2
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• pp.27-40
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• 1985

This study aims at the development of computer Program for the deformation analysis of soft clay layers, and using this computer program, study the constraint effect of deformation- heaving, lateral displacement-of the soft clay layers reinforced with sheet pile at the tip of banking or improvement of soft clay layer up to hard strata, under intact state (natural) and the state of vertical drain respectively. For this study, Biot's consolidation theories and modified Cam-clay theory for constitutive equation for FEMI were selected and coupled governing equation, and christian-Boehmer's technique was applied to solve the coupled relationship. The following results are obtained. 1. Sheet pile or improvement of soft clay layer to the hard strata work well against the settlement of neighboring ground. B. In view of restriction of heaving or lateral displacement, sheet pile is not supposed to be of use. 3. Sheet pile is of effect only when vertical drain is constructed for acceleration of consolidation and load increases gradually. B. The larger the rigidity of improvement of layer to hard strata is, the less settlement occurs.

• 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.15 no.3
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• pp.3-16
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• 1999

A series of model tests was conducted to investigate the one-dimensional consolidation behavior of an improved ground where sand compaction piles(SCP) were either fully or partly installed in the model clay ground. In order to check the one-dimensional consolidation settlement and stress concentration ratios, earth pressure, pore pressure transducers and dial gauges were installed in the model clay ground. The test results revealed that the consolidation settlement of the partly penetrated SCP ground was larger than that of the fully penetrated SCP ground, and the stress concentration ratios (m) of the fully penetrated SCP ground were higher than these of the partly penetrated SCP ground. The stress concentration ratio was decreasing with the increase in the penetration depth of SCP.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4C
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• pp.229-238
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• 2006

Observed field behaviors are frequently different from the behaviors predicted in the design state due to several uncertainties involved in soil properties, numerical modeling, and error of measuring system even though a sophisticated numerical analysis technique is applied to solve the consolidation behavior of drainage-installed soft deposits. In this study, genetic algorithms are applied to back-analyze the soil properties using the observed behavior of soft clay deposit composed of multi layers that shows complex consolidation characteristics. Utilizing the program, one might be able to appropriately predict the subsequent consolidation behavior from the measured data in an early stage of consolidation of multi layered soft deposits. Example analyses for drainage-installed multi-layered soft deposits are performed to examine the applicability of proposed back-analysis method.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.6
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• pp.39-45
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• 2016

In this paper, analyzes the characteristics of self-weight consolidation on the dredged clay according to the fines content and falling height. Research was performed with the dredged clay sampled by Sae-mangeum field site. Classification of fines content was performed by sieve analysis test. After adjusting the fine content, self-weight consolidation tests were carried out focussing on the variation of fines content and falling heights. From the test results of the self-weight consolidation test, samples with high fines content had reached sedimentation completion more later than ones with less fine content samples. In other words, the start of self-weight consolidation was slowing down with increasing of fines content. Also, from the test results of calculating the coefficient of sedimentation consolidation, the coefficient value were increased with the fines content increases. In addition, the change of sedimentation ratio and volume ratio showed more higher changed value as the fine content increases. Thus, it is important to consider the fines content when estimate the settlement time of dredged soil in field dredge work.