• Current Research on Agriculture and Life Sciences
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• v.2
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• pp.98-108
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• 1984

Generally, in case of constructing the embankments on the soft clay layers, one-dimensional consolidation settlement under the assumption of a middle position stress in a single layer makes a great difference with the integral value, ie. the final settlement. Consequently, to find how many equal segments of the soft clay layer are needed to converge into the integral value and which position should be taken as a position of mean stress, authors compared the theoretical value of the settlement due to one-dimensional consolidation with the practical value of the settlement due to two dimensional consolidation. The obtained results are as follows. 1) The practical value of the two-dimensional consolidation settlement can be estimated by the 74-83% theoretical value of the one-dimensional consolidation settlement. 2) When the soft clay layer was cut into 8-16 equal segments according to the depth, one-dimensional consolidation settlement converge into the integral value. 3) Assuming a total soft clay layer as a single one, the depth of a mean stress position is 0.29-0.37 of the thickness of the total soft clay layer. 4) The Hyperbola Method which presumes the long-term settlement from the short-term practical value of settlement is credible, because all practical value of the settlement are in safe side of the standard error of estimation and the correlation coefficient is up to 0.95.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.02a
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• pp.78-83
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• 1999

The ultimate settlement of soft clay consists of three parts: $\circled1$ immediate settlement, S$\sub$d/; $\circled2$ Primary consolidation settlement, S$\sub$c/; $\circled3$ Secondary consolidation settlement, S$\sub$s/. In general, S$\sub$c/ can be accurately calculated by one-dimensional consolidation and S$\sub$s/ or S$\sub$d/ may be ignored. This paper focuses on a calculation method to estimate the immediate settlement induced by lateral deformation of subgrade, to which shear stress is applied by embankment on soft ground. Immediate settlement and consolidation settlement are discussed by comparing the field measurement of the Yangsan test embankment on treated soft foundation by vertical paper drains.

• Journal of Industrial Technology
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• v.23 no.A
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• pp.109-118
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• 2003

This paper is results of numerical works of investigating effects of horizontal drain arrangements on vacuum consolidation. Extensive numerical analyses were carried out to find the appropriate arrangements of horizontal drain of vacuum consolidation. Commercially available program of CRISP, well known to be good to modelling the behavior of clay material, was used Cam-clay model, based on the Critical State of Soil Mechanics(CSSM), was used to simulate the geotechnical engineering behavior of clay. Model test results carried out previously in the laboratory were compared with numerically estimated results and it was found that results about consolidational settlement with times were in good agreements. Based on this confirmation, parametric numerical study was performed to investigate effects of horizontal drain arrangements on vacuum consolidation with changing the vertical and horizontal spacings between drains for the given soil properties and vacuum. The effect of distance of drain located in top layer from the surface of the ground on the settlement due to vacuum was also investigated. As a results of numerical analyses, appropriate arrangements of horizontal drain to maximize the consolidation settlement due to vacuum were found. The mechanism of vacuum consolidation about the vacuum pressures being transferred to the effective stresses around drains was also evaluated.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.02a
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• pp.70-77
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• 1999

Consolidation settlements on soft clay are often large and potentially damaging to structures. Currently, large-scale projects are in progress in Korea. These structures will be constructed on both thick and soft clay layers, and so the accurate evaluation of magnitude of settlement is required at every step in design and construction. Especially, secondary compression play an important role in consolidation settlements on soft clay. Generally, the magnitudes of secondary compression are evaluated by laboratory and in-situ consolidation tests or by empirical $C_{a/}$ $C_{c}$ relationships. The empirical $C_{a/}$ $C_{c}$ may not be only economical, but a fast and powerful tool in estimating secondary consolidation settlement. However, databases of the $C_{a/}$ $C_{c}$ relationship for sites in Korea are currently insufficient. The purpose of this study is to investigate the relationship of $C_{a/}$ $C_{c}$, on marine clay near the southern sea in Korea. In this study a series of incremental loading consolidation tests (measuring base pore water pressure) are performed. It was found that the $C_{a/}$ $C_{c}$ on undisturbed marine clay equaled 0.0397. This value is similar to the value proposed by Mesri and Castro(1987) for inorganic clay and silt. and silt. and silt.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.737-742
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• 2009

This research intends to clarify the engineering characteristics of compression index which plays the most important role in the calculation of consolidation settlement, based on the survey of the clay in the estuary of Nakdong River. In addition, it will analyze the parameters of soil and the correlation between the parameters and the existing relation, especially the correlation with compression index, through which it will propose a proper relation for the parameters of clay in this area. As a result of the study, the relation between the settlement and the compression rate using compression index showed 13% settlement error on the average. It is judged that this number can be used for forecasting the consolidation characteristics and the settlement for brief (preliminary) design when the difference between the execution settlement and the measuring settlement is regarded to be 15%.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.11a
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• pp.51-56
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• 2004

The sand compaction pile (SCP) method, which forms a composite ground by driving sand piles into clay deposit, is the most commonly used soil improvement techniques in many countries for more than 30 years. Installation of sand compaction piles reduces the amount of consolidation settlement and increases the bearing capacity of soft clay deposit. In this paper, field survey conducted to investigated the consolidation behavior of the composite ground improved by SCPs. It is suggested that the measured consolidation velocity is later than design theory, however measured consolidation settlement is higher than design theory.

• Geotechnical Engineering
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• v.13 no.1
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• pp.137-146
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• 1997

In this study, a large consolidation test was carried out to estimate the consolidation behaviour of dredged clay ground improved by horizontal drain using plastic board drain with a vacuum pressure. The test results were analyzed by a numerical simulation using potential consolidation theory applied to a hollow cylinder. The rapid decreases in pore pressure and the drain speed in the plastic board indicate that the consolidation occurred quickly after the vacuum state was applied to the test soil. According to the numerical analysis obtained by applying the linear potential consolidation theory to a clay hollow cylinder with external radial drainage, the pore pressure is affected by the strain and the permeability of the soil rather than by the diffusion types. Therefore, measured surface settlement agreed with the numerical solution at the point where consolidation pressure increasing rate u: -0.5. Also the behaviour of the clay layer settlement in the place where the drain was installed was similar to that shown in Barron's consolidation theory. Finally, the design and construction procedure including the selection of the appropriate arrangement of horizontal drains were discussed based on the results of the laboratory tutsts. It is also shown that the potential consolidation theory make it possible to predict consolidation behaviour in the field using horizontal drains exactly.

• Journal of the Korean GEO-environmental Society
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• v.25 no.4
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• pp.5-12
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• 2024

In the case of creating a site in the reclaimed land (public waters), due to the nature of the coastal sedimentary ground, large-scale construction materials are required, It is necessary to utilize soft clay, which is inevitably generated during construction of the complex, as a fill material in terms of resource recycling and economic aspects (reducing the amount of embankment required). In this study, changes in the consolidation characteristics of cut-out disturbed soft clay due to the recycling of soft clay soil were identified, and a consolidation settlement design plan was proposed. Through the results of the consolidation test of the study site, the change in consolidation characteristics (compression index reduction, precede load uncountable) due to disturbance (cutting) was confirmed, the method of calculating (consolidation settlement) the filling clay layer as the composite target layer (consolidation target layer, loading load layer) was analyzed as a result consistent with the actual behavior.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1042-1050
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• 2008

In this study, SCP method was used by purpose to improve loose sand and soft clay that is drilled Sand Compaction Pile in underground. Settlement behavior of field analyzed through SCP method. When sand Compaction Pile drilled in clay, forming composite ground that foundation and Sand Compaction Pile behavior. According to SCP method can expect bearing capacity improvement, Settlement reduction, lateral flow protection. SCP increase the consolidation settlement of ground and it reduce settlement for that purpose increase liquefaction resistance, lateral Resistance. Because SCP had been widely used for sand. Area of Inchon-A by sand compose clay and silt to upper Ground and compose soft clay to under ground. After pre-loading, it measured settlement by extensometer and settlement extensometer that purpose of ground improvement with 13% in replacement ratio. The result analyzed settlement behavior is similar to Multi-layered Ground that it happened to elastic settlement at upper ground and to consolidation settlement at under ground.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.875-883
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• 2003

Slurry clay has much higher water content than liquid limit of clay and even if small loads apply, it suffers a great settlement. Accordingly it is very difficult to perform a general consolidation test about slurry clay because of high water content. In this study consolidation tests have been performed successfully using Rowe Cell Tester about 1 remolding clay and 3 slurry clays with a water content of 100%, 133% and 150%. From the test results compression index characteristics, secondary compression index characteristics and consolidation coefficient characteristics have been investigated about slurry clay and remolding clay. Also two kinds of theory, by Terzaghi theory and by Mikasa theory, has been used to calculate consolidation coefficients. Compared to the calculation results, they had a similar value of consolidation coefficient. However if Mikasa theory is applied in the field design, the period which reach to the required consolidation degree will be much reduced compared to the period by Terzaghi theory because the time coefficient T$\_$v/ by Mikasa theory is far smaller than T$\_$v/ by Terzaghi theory.