• Journal of the Korean Geotechnical Society
• /
• v.23 no.8
• /
• pp.129-135
• /
• 2007

In order to analyze the effect of fines content on sedimentation and self-weight consolidation characteristics of dredged soil, a series of self-weight consolidation tests with different fines content were conducted. From the experimental test results on dredged soils, it was found that the coefficient of sedimentation and consolidation is correlated with water content. And it is related to fines content as well. So, in this study, correlation between fines content and the coefficient of sedimentation and consolidation has been proposed. And it is expected that the coefficient of sedimentation and consolidation can be estimated by the percentage of fines content.

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

• Proceedings of the Korean Geotechical Society Conference
• /
• 2002.10a
• /
• pp.597-604
• /
• 2002

This paper reviews depositional environments of marine deposits along the Nakdong river and then analytical solution of self-weight consolidation considering artesian pressure is made to find consolidated state. It's known that this area is in the under-consolidated state by the artesian pressure(u$\_$a/=0.3kg/$\textrm{cm}^2$) and the distribution of the artesian pressure is not linear but parabola. In predicting consolidation settlement for soft grounds improved by vertical drain, it is emphasized that the self-consolidation by sudden dissipation of artesian pressure should be considered.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2002.03a
• /
• pp.491-498
• /
• 2002

Dredged and reclaimed soft clays form slurry state which is very high water content and very low shear strength, experience large self-weight consolidation, nonlinear compressibility and permeability phenomenon would take place. In this case, a material functions which represent variety effective stress-void ratio-permeability relation (especially very low effective stress), are should be determined to predict nonlinear finite strain consolidation phenomenon forehand In this study, large slurry consolidometer with a 380mm diameter and a 1400mm height which is able to consolidation and permeability test, was developed to determine material function of very soft clay with a 500% initial water content clay, self-weight consolidation and low stress level consolidation (1Kpa, 3Kpa, 6Kpa, 12Kpa) was conducted and after each consolidation step permeability test also conducted. after final consolidation step, a constant rate of strain consolidation was conducted with undisturbed sample obtained from the large consolidometer. On the above result, material function was determined and laboratory test was modelled to evaluate its validity, numerical analysis on th field was compared to other method.

• Journal of the Korean Geotechnical Society
• /
• v.26 no.11
• /
• pp.17-28
• /
• 2010

Vertical drains are commonly used to accelerate the consolidation process of soft soils, such as dredged materials, because they additionally provide a radial drainage path in a deep soil deposit. In practice, vertical drains are commonly installed in the process of self-weight consolidation of a dredged soil deposit. The absence of an appropriate analysis tool for this situation makes it substantially difficult to estimate self-weight consolidation behavior considering both vertical and radial drainage. In this paper, a new method has been proposed to take into account both vertical and radial drainage conditions during nonlinear finite strain self-weight consolidation of dredged soil deposits. For 1-D nonlinear finite strain consolidation in the vertical direction, the Morris (2002) theory and the PSDDF analysis are adopted, respectively. On the other hand, to consider the radial drainage, Barron's vertical drain theory (1948) is used. The overall average degree of self-weight consolidation of the dredged soil is estimated using the Carillo formula (1942), in which both vertical and radial drainage are assembled together. A series of large-scale self-weight consolidation experiments being equipped with a vertical drain have been carried out to verify the analysis method proposed in this paper. The results of the new analysis method were generally in agreement with those of the experiments.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.10a
• /
• pp.1693-1706
• /
• 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
• /
• v.22 no.12
• /
• pp.5-14
• /
• 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
• /
• 2006.10a
• /
• pp.515-520
• /
• 2006

Yano method had been used in predicting the settlement of self-weight consolidation of dredged soil in the construction of reclamating the dredged soil. Its estimation was found to show some different results from field measurements. The numerical analysis with PSDDF was peformed find such differences, considering the effect of desiccation on the consolidation during the remaining time after reclamation. For the parametric study, numerical analyses with/without consideration of desiccation were carried out with changing the conditions of desiccation such as the number of placing the fill and the time period between each placement. As results of analysis, estimations about consolidation settlement and distribution of water contents with consideration of desiccation was in good agreements with field measurements. It was also found that the number of placing the fill and the time period between each placement did not affect the behavior of self-weight consolidation as much as the effect of desiccation.

• Journal of the Korean Geotechnical Society
• /
• v.16 no.4
• /
• pp.149-156
• /
• 2000

Sedimentation and self-weight consolidation tests in cylinder and large model tank and field measurement such as settlement and pore water pressure at each layer by wireless automatic instrumentation system were carried out to investigate the behaviour of dredged marine clay fill. The consolidation behaviour for each reclaimed layer was analyzed from these measured data and numerical analysis result using finite strain consolidation theory. It was fond from this study that the consolidation behaviour of dredged clay fill is heavily dependent on the filling process.

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