• 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.

• Journal of the Korean Geosynthetics Society
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• v.13 no.4
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• pp.33-43
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• 2014

Recently, the case to construct the structure on the soft clayey ground has increased and in order to the reduction of the cost of construction and maintenance on the social infrastructure facilities we have been trying to improve the soft clayey ground using the existing methods such as the pre-loading method and the vertical drain method. Like this, when various ground improvement methods are applied on the soft clayey ground, a long-term consolidation settlement will be key issue due to low permeability coefficient of cohesive soil. According to existing research results that relate to the consolidation settlement, the loading periods for existing the standard consolidation test (Oedometer test) to obtain the consolidation parameters are needed for minimum ten days or more. Therefore, in this study, the standard consolidation test (24 hours step-loading) and constant strain rate consolidation test changed by strain rate was performed using the remolded marine clay on Gwangyang bay composed of a soft clayey ground of the south-west coast. From the laboratory test results, the characteristics of compression, strain-effective stress relations by constant strain rate and the variation characteristic of the pore water pressure by different of loading speed and the relation between consolidation parameters and constant strain rate are compared and analyzed.

• Journal of the Korean GEO-environmental Society
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• v.8 no.6
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• pp.37-43
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• 2007

The interface layer having different consolidation properties and nonlinear material function with permeability needs to be considered to predict consolidation behavior. In this study, interface equation between different layers has been derived and then applied to existing finite difference scheme for conducting consolidation analysis. These results have been compared with those by conventional method in which different layers are converted to single layer having conversion value of properties. Also, although the conventional consoilidation analysis is used to consider non-linearity of the permeability with effective stress, an approximated nonlinear method as a function of consoilidation coefficient with effective stress have been developed and applied to the consoilidation analysis for various cases.

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.75-81
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• 2000

The anisotropy of soils has an important effect on stress-strain behavior. In this study, an attempt has been made to implement artificial neural network model for modeling the stress-strain relationship and predicting the undrained shear strength of normally consolidated clay with varying consolidation pressure ratios. The multi-layer neural network model, adopted in this study, utilizes the error back-propagation loaming algorithm. The artificial neural networks use the results of undrained triaxial test with various consolidation pressure ratios and different effective vertical consolidation pressure fur learning and testing data. After learning from a set of actual laboratory testing data, the neural network model predictions of the undrained shear strength of the normally consolidated clay are found to agree well with actual measurements. The predicted values by the artificial neural network model have a determination coefficient$(r^2)$ above 0.973 compared with the measured data. Therefore, this results show a positive potential for the applications of well-trained neural network model in predicting the undrained shear strength of cohesive soils.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.4
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• pp.136-145
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• 2011

For a massive project related to building national industrial complexes on a soft ground applied to PVD after dredging and hydraulic fill, laboratory tests were carried out using undisturbed sample taken from various depth. Piezocone penetration and dissipation tests were carried out to assess horizontal coefficient of consolidation and initial stress in field. The ground consists of upper dredged fill and lower original clay layer having both similar marine clays. It should be, however, considered as multi-layered soft ground having different initial void ratio, initial water content, initial effective stress, and permeability and compressibility with directions. To assess initial stress of those soft layers in which have different stress history related to consolidation, CPTu test results, especially excess pore water pressure, were analyzed. It allows to find out distribution of excess pore water pressure and initial stress inner original clay layer.

• Journal of the Korean GEO-environmental Society
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• v.16 no.7
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• pp.15-22
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• 2015

This study gives the characteristics of sedimentation-consolidation and surface strength for dredging and landfill areas in each coast. For the analysis of the sedimentation-consolidation characteristics, the column tests were performed and the results were compared with existing various literatures and design reports for dredged soil disposal. The surface strength of landfill soils of west and south coast were investigated by using the portable cone tester. As a results of analysis, the coefficient of sedimentation-consolidation on south coastal dredging soils is more sensitive with variation of initial water contents than on the west coastal dredging soils. And the surface strength of the dredging landfills is a higher in the west coast than in the south coast. Finally, the results of this study will be utilized as a basis data for analysis and design in the field of dredging and landfill.

• The Journal of Engineering Geology
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• v.23 no.4
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• pp.503-510
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• 2013

Shear wave velocity is widely used as an parameter for investigating subsurface characteristics and for obtaining the design parameters based on theoretical equations. This study seeks to estimate the coefficient of shear wave velocity in Busan clay via laboratory tests. Eight specimens were extracted at depths of 10, 12, 15, 20, 22, 25, 30, and 31 m. The specimens were subjected to the consolidation test to determine the relationship between effective stress and shear wave velocity. The relationship shows a non-linear trend and is similar to the results of a previous study. The coefficient shows constant coverage and a relationship between ${\alpha}$ and ${\beta}$ is suggested. The results demonstrate that this coefficient could be used as a reference value to determine engineering parameters based on the shear wave velocity.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.23-29
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• 2003

In this paper, effects of the acidification of ground and the chemical additive materials-ferric oxide, calcium chloride and calcium sulphate on the compressibility characteristics of the marine clay treated with quick lime were investigated. The rapid inflection point method was carried out. Results showed that the compression index of the untreated marine clay increased as the pH of pore water decreased. Also, the preconsolidation pressure, the coefficient of consolidation and the coefficient of permeability of the untreated marine clay decreased with pH of pore water. In the case of the marine clay treated with the quick lime-calcium chloride, the compression index decreased and the coefficient of consolidation and the coefficient of permeability increased. Specially, the preconsolidation pressure of sample treated with the quick lime-ferric oxide was higher than that of another samples.

• Journal of the Korean Geotechnical Society
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• v.26 no.11
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• pp.99-110
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• 2010

A fundamental study of the pile-soil systems subjected to negative skin friction in soft soil was conducted using the long-term field measurements. The emphasis was on the identification of the magnitude and distribution of skin frictions ($\alpha$ and $\beta$ coefficients) in bitumen coated and uncoated piles. A skin friction coefficient of instrumented piles is back-calculated by varying degrees of consolidation (U) of surrounding soils. It is shown that the bitumen coated pile is capable of reducing the negative skin friction up to almost 50 to 90 percents. Through comparisons with the existing friction coefficient values ($\alpha$ and $\beta$ coefficients), the calculated coefficients are within the appropriate range, and thus we can suggest basic materials to estimate the realistic pile behavior in the short-term and long-term analysis.

• Journal of the Korean GEO-environmental Society
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• v.3 no.3
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• pp.15-25
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• 2002

The permeability coefficient is one of the fundamental engineering properties of soft clays. Consolidation process as well as migration of pollutants in soil are affected the permeability coefficient, which generally decreases with the reduction in void ratio during consolidation. After Kozeny(1927) and Carman(1956), many researchers have proposed the relationships between void ratio and permeability in such forms as; (1) log e - log k(1+e), (2) e - log k, or (3) log e - log k. Constant rate of strain (CRS) tests was performed with undisturbed samples obtained at Kunsan and Kimhae deposits, which are representative Korean marine clay. From the results of the tests, the relationships were found valid for Kunsan and Kimhae clays. The experimental correlation $C_k=0.5e_o$ was satisfied with Kimhae clay but not with Kunsan clay.