• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.1198-1209
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• 2009

In this study, an experimental research on the acceleration effect of dredged soil's self weight consolidation with seepage consolidation and PBD was conducted. The middle-sized consolidation equipment had been manufactured in order to investigate the acceleration of sedimentation and self-weight consolidation by PBD and a lower drainage. Seepage pressure was applied to the PBD installed in the center of the test equipment and a drainage by seepage pressure was allowed. The comparison between cases with and without PBD and seepage pressure reveals that the quantity of drained water and the amount of settlement was nearly 1.2 times to 3.68 times greater in the case with PBD and seepage. Early consolidation completion and the use of reclaimed site are expected due to the acceleration of settlement and increase of the quantity of reclamation if PBD is installed while being reclaiming using the result of the research.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1693-1706
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• 2008

It is of importance to determine the zero effective stress void ratio($e_{00}$), which is the void ratio at effective stress equal to zero, and the relationships of void ratio-effective stress and of void ratio-hydraulic conductivity for characterizing non-liner finite strain consolidation behavior for ultra-soft dredged materials. The zero effective stress void ratio means a transitional status from sedimentation to self-weight consolidation of very soft soil deposits, and acts as a starting point for self-weight consolidation in the non-linear finite strain numerical analysis such as PSDDF. In this paper, a new method for determining the zero effective stress void ratio has been introduced with the aid of measuring electrical resistivity of the specimen. A correlation between the zero effective stress void ratio and the initial slurry void ratio has been proposed, which can be used in PSDDF analysis as an input parameter. Combining all of the accessible experimental data, the consolidation characteristics of a dredged soil from the Incheon area has been studied in detail.

• Journal of the Korean Geotechnical Society
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• v.19 no.4
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• pp.155-165
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• 2003

A series of one-dimensional cylinder sedimentation test, seepage consolidation test and two-dimensional deposition model test were conducted to examine the characteristics of deposition and volume change of dredged soils containing the high water content, and these experimental results were compared with the sedimentary conditions of actual dredged-reclaimed fields to obtain the relations of a volume change by settling what is required for design. In addition, the change of water content and the distribution of fine grained soils after sedimentation were investigated. Thus, it was concluded that deposition height increased lineary as substantial soil volume increased, and also the elevation of interface increasea proportionately at both the starting time and the finishing time of virtual self-weight consolidation in one-dimensional sedimentation. Furthermore, the two-dimensional model test results were shown to describe the plain distribution of water content and fine grained silt where dredged soil was deposited by two dimensional flowing, and the water content was distributed to wide range from the minimum water content 30% to maximum 180% according to the passed amount of №200 sieve percentage.

• Journal of the Korean Geotechnical Society
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• v.22 no.12
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• pp.5-14
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• 2006

In general, the dredged ground was composed of a big difference of sediment shape through segregating sedimentary of finer soil in case of reclaiming by dredged coarse soils. Therefore, this study was performed to evaluate the change of settling velocity of flow, and the density of sedimentary which is based on settling tests and self-weight consolidation tests, and consolidation test by seepage force according to the percentage of coarse of Kunsan dredge soils. The Yano's method has been applied to estimate the settlement of self-weight consolidation in finer soils at design but it only considers pouring water content and elevation of interface, therefore the other method needs to be introduced for the exact prediction of the settlement of coarse soil in which the segregation sedimentation is occurring. In this study, the settlement of self-weight consolidation was calculated by the change of the density of segregating sedimentary of coarse and finer soils which was analyzed by Yano's method to extend a serious of researches. The self-weight consolidation by Yano's method will not reflect the segregated settling in dredging coarse soil under 40% of #200 passing percentage. As a result, the evaluation technique of settlement of self-weight consolidation considering a change of the density of segregating sedimentary is suggested as a reasonable method that considers the sediment shape of coarse soil.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.10a
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• pp.481-489
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• 2006

Two dimensional diffusion model test was conducted to investigate the sedimentation properties and consolidation process of reclaimed ground using dredging coarse soil which is composed of passing amount 20 percentage and 45 percentage of #200 sieve size respectively. The passing amount of #200 sieve size affected on sedimentation properties. The coarse soil which is passing amount of 20 percent showed that the sedimentation structure was layered type and passing amount of 45 percentage was wall-partition type according diffusion distance. Furthermore, the water content of surface and section, and distribution of fine soil were changed according to diffusion distance. and the change amount of pore water pressure and strength property when soil is diffused, segregated and accumulated can be applied efficiently in design of dredging and reclamation.

• Journal of the Korean Geotechnical Society
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• v.27 no.10
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• pp.45-54
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• 2011

In this study, the consolidation characteristics are investigated on the artificial soil mixture of kaolinite, fine soils representing dredged soils and reclaimed coal ash from the ash ponds. A large sedimentation chamber was designed and manufactured to produce the artificial soil mixture with uniform stress history. In order to examine the consolidation characteristics in lateral and vertical directions, standard consolidation and Rowe Cell tests were performed. From the results of standard consolidation tests, the artificial soil mixture with coal ash showed lower compressibility and the larger consolidation coefficients enough to aid in early stabilization of the reclaimed sites compared with the kaolinite only. Also, in order to examine the consolidation characteristics when applying vertical drains, the drainage material was installed and tested in the Rowe Cell. The Rowe Cell test results show that the artificial soil mixture yields higher coefficient of consolidation. Thus, the application of artificial soil mixture on the reclaimed sites can shorten the consolidation time.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.4
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• pp.953-963
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• 1994

Treatment techniques of soft clay layers is needed sophisticated technology in civil engineering. Especially, dredged and reclaimed clay has high liquid limit and water content, so it is difficult to use. Now it comes to the applicability as good construction materials by predicting the behaviors. This paper is to evaluate the characteristics of sedimentation and self-weight consolidation of extremely soft clay, and is to find the way of applying model test result of reconstructing the in-situ condition to design. The consolidation properties of soft clay layers changing the size of the cell are investigated by large-scale consolidation test apparatus and the behaviors of self-weight consolidation are predicted by numerical analysis.

• Geomechanics and Engineering
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• v.25 no.2
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• pp.159-170
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• 2021

Particle size of tailings in different areas of dams varies due to sedimentation and separation. Saturated hydraulic conductivity of high-stacked talings materials are seriously affected by void ratio and particle breakage. Conjoined consolidation permeability tests were carried out using a self-developed high-stress permeability and consolidation apparatus. The hydraulic conductivity decreases nonlinearly with the increase of consolidation pressure. The seepage pattern of coarse-particle tailings is channel flow, and the seepage pattern of fine-particle tailings is scattered flow. The change rate of hydraulic conductivity of tailings with different particle sizes under high consolidation pressure tends to be identical. A hydraulic conductivity hysteresis is found in coarse-particle tailings. The hydraulic conductivity hysteresis is more obvious when the water head is lower. A new hydraulic conductivity-void ratio equation was derived by introducing the concept of effective void ratio and breakage index. The equation integrated the hydraulic conductivity equation with different particle sizes over a wide range of consolidation pressures.

• Geomechanics and Engineering
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• v.16 no.2
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• pp.125-140
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• 2018

Tianjin, which is located on the west shore of the Bohai Sea, is part of China's Circum-Bohai-Sea Region, where very weak clay is deposited. From the 1970s to the early $21^{st}$ century, Tianjin marine clay deposits have been the subject of numerous geotechnical investigations. Because of these deposits' geological complexity, great depositional thickness, high water content, large void ratio, excessive settlement, and low shear strength, the geotechnical properties of Tianjin marine clay need to be summarized and evaluated based on various in situ and laboratory tests so that Tianjin can safely and economically sustain more infrastructure in the coming decades. In this study, the properties of Tianjin marine clay, especially its consolidation properties, are summarized, evaluated and discussed. The focus is on establishing correlations between the geotechnical property indexes and mechanical parameters of Tianjin marine clay. These correlations include the correlations between the water content and the void ratio, the depth and the undrained shear strength, the liquid limit and the compression index, the tip resistance and the constrained modulus, the plasticity index and the ratio of undrained shear strength and the preconsolidation pressure. In addition, the primary consolidation properties of Tianjin marine clay, such as the intrinsic compression line (ICL), sedimentation compression line (SCL), compression index, $C_c$, coefficient of consolidation, $C_v$, and hydraulic conductivity change index, $C_{kv}$, are evaluated and discussed. A secondary consolidation property, i.e., the secondary compression index, $C_a$, is also investigated, and the results show that the ratio of $C_a/C_c$ for Tianjin marine clay can be used to calculate $C_a$ in secondary consolidation settlement predictions.

• Geomechanics and Engineering
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• v.1 no.3
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• pp.241-257
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• 2009

The one-dimensional compressibility of sand is an important property for the estimation of settlement or deformation of sand deposits. The $K_0$ value of sand is also an important design parameter. Experimental results are presented in this paper to study the compressibility of sand in $K_0$ consolidation tests. The $K_0$ consolidation tests were carried out using a triaxial cell and a plane-strain apparatus. Specimens prepared using both the moist tamping and the water sedimentation methods were tested. The testing data demonstrate that the type of testing apparatus does not affect the $K_0$ measurement if proper boundary conditions are imposed in the tests. The data also show that the compressibility and the $K_0$ value of loose sand specimens prepared using the moist tamping method are very sensitive to the variation of void ratio. The $K_0$ values measured from these tests do not agree with the $K_0$ values calculated from Jaky's equation. The compressibility and $K_0$ values of sand obtained from tests on specimens prepared using different preparation methods are different which may reflect the influence of soil fabrics or structures on the one dimensional compression behavior of sand.