• Journal of the Korean Geotechnical Society
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• v.23 no.8
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• pp.129-135
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• 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 Geotechnical Society
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• v.36 no.3
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• pp.25-36
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• 2020

In this research, three-point bending tests were performed using a rectangular frozen specimen with various fine contents and notch offset distance from the center of the specimen to investigate the fracture characteristic of the frozen sand. Based on the test results, mode I fracture toughness was calculated, and mixed-mode (mode I + II) fracture characteristics were investigated using the fracture energy which was calculated until the maximum point of the load-displacement curve. As the fine contents increase, the peak load and mode I fracture toughness increase until 10% fine contents. Furthermore, as the notch offset distance increases, the fracture energy required for crack start also increases due to the increase in mode II load at the crack tip.

• Journal of the Korean GEO-environmental Society
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• v.16 no.6
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• pp.31-38
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• 2015

Recently, the participation on the development of the natural gas pipeline in Russia as well as the recent construction of the second Korean Antarctic research station, the Jangbogo station provide the research interests on the behavior of the permafrost ground. To investigate the effect of fines on the mechanical responses of frozen sands, unconfined compression tests were performed on the frozen sands with 0, 5, 10 and 15% of fine contents at -5, -10 and $-15^{\circ}C$. The poorly graded (SP) Joomunjin sand and kaolinite, silt with low plasticity (ML) were used for the preparation of the frozen soil specimens. The mechanical responses of the tested soils were investigated via unconfined compression tests in the temperature controlled laboratory and analyzed in terms of peak unconfined compressive strength and secant modulus at 50% of the peak strength. As the fine contents increase, the unfrozen water contents increase and thus the strength and stiffness of frozen soils decrease. The increment of the stiffness and strength due to the temperature decrease vary with the fine contents.

• Journal of the Korean GEO-environmental Society
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• v.18 no.1
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• pp.31-35
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• 2017

The mechanical characteristics of frozen sand greatly depend on the frozen temperature and the fine contents according to the previous study by Chae et al. (2015). There are two hypotheses to explain this experimental results; one is the unfrozen water contents greatly affected by the fine contents and frozen temperature and the other is the sand particle spacing greatly affected by the pore-ice. To evaluate the latter hypothesis, the micro X-ray CT scan was performed. The micro X-ray CT scanning, one of the actively performed interdisciplinary research area, has a high resolution with micrometer unit allows to investigate internal structure of soils. In this study, X-ray CT technique was applied to investigate the effect of the frozen temperature and fine contents on the sand particle minimum and average spacing with the developed image processing techniques. Based on the spacing analysis, the frozen temperature and fine contents have little influence on the sand particle spacing in the frozen sand specimens.

• Journal of the Korean Geosynthetics Society
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• v.10 no.1
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• pp.19-28
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• 2011

This paper presents the results of an investigation into the effect of cyclic freezing-thawing on the compressive strength characteristics of decomposed granite soils. A plane strain compression (PSC) tests were performed on a series of test specimens with different freezing-thawing cycles and fine contents to investigate the change in compressive strength under the process of freezing-thawing cycles. Also performed were scanning electron microscope (SEM) tests to investigate the change in structural rearrangement from a micro-scale point of view. The test results showed that the soil particles tend to conglomerate when subject to cycles of freezing and thawing, and that the soil with less fines exhibited decreased shear strength due to the cyclic freezing-thawing while the soils with a larger fine content showed the opposite trend.

• Journal of the Korean Geotechnical Society
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• v.37 no.8
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• pp.5-13
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• 2021

Liquefaction behaviors of two natural silty samples containing fines including clay of 50% or more (Sample No.1 was silt 44.1% and clay 8.8%, sample No.2 was silt 57.2% and clay 12.4%) were examined by a cyclic triaxial test. According to the results on samples containing 50% or more of fine particles, an increase in the fine content decreases the liquefaction resistance of the sample. In other words, when the fine content increases, the liquefaction state of sample is reached with a small number of cyclic loads. In the relationship between the excess pore water pressure ratio and the number of cycles, the slope of the excess pore water pressure ratio increases more steeply as the fine content increases. As a result of analyzing the liquefaction behavior of the two silts with the content of clay contained in the fines, liquefaction occurred more easily in the No.2 silt with high clay content. This result shows that the clay contained in the fines affects the liquefaction behavior of the silt.

• Journal of the Korean Geosynthetics Society
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• v.22 no.3
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• pp.47-59
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• 2023

In this research, laboratory tests were conducted on clayey sand (SC) to analyze its physical properties, compaction/permeability characteristics, and stress-strain behavior. The main objective was to determine the transitional fines content at which the mechanical properties of sand transition to those of clay, resulting in a change in the geotechnical behavior of the material. Additionally, to assess the practical applicability of SC soil, field data from a soft ground improvement site with significant settlement issues were collected. The settlement characteristics derived from laboratory tests and numerical simulations were then compared and analyzed in relation to the actual settlement data obtained from the field, aiming to evaluate the suitability of the SC soil as a compaction target layer. The laboratory tests and compaction analysis showed that the SC soil exhibited a distinct change in mechanical properties, shifting from sandy behavior to clayey behavior when the fines content exceeded 25%. This transition in mechanical behavior was found to be closely correlated with the content of clay particles within the material. Through numerical simulations of the soft ground site, it was verified that the use of clayey sand with a fines content exceeding the transitional level as a compaction target layer resulted in settlements that closely aligned with the measured settlements, with an average agreement of 91.2%. Based on these findings, it is deemed advisable to incorporate clayey sand with a fines content exceeding the transitional level as part of the compaction target layer in the design of soft ground improvements.

• Journal of the Korean Geotechnical Society
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• v.27 no.6
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• pp.63-79
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• 2011

In this study relative density tests of bottom ash and standard sand were carried out. And cyclic triaxial tests for samples with the relative density of 40%, 55%, and 70% were carried out on the basis of the test results. Cyclic triaxial tests were also conducted for fines content with 55% relative density. Residual samples were divided into No.40, No.60, No.60, and No.100, and No.200. In order to avoid crashing that can happen when compaction of the sample is initiated, bottom ash was crushed using the a compact mold. In consideration of the crushing characteristics of each residual samples, the fragmentation rate increased up to 30%, which led to the adjustment of fine-grained amount to 10%, 20%, and 30%. Through the repative triaxial test in accordance with the relative density, resistant characteristics of the liquefaction of bottom ash was analyzed. Test results show that, crushing strength of bottom ash was smaller than that of standard sand, resulting in different liquefaction behavior characteristics. And we could find fines content with maximum resistant characteristics of the liquefaction.

• Journal of the Korean Geotechnical Society
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• v.17 no.6
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• pp.235-244
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• 2001

Liquefaction may be caused by sudden decrease in the soil strength under undrained conditions. This loss of soil strength is related to the development of excess pore pressures. During this study, fines content affects the maximum and minimum void ratios are investigated. The results of static and cyclic triaxial test on silty saturated sands are presented. These tests are performed to evaluate liquefaction strength and static and cyclic behavior characteristics. The samples are obtained from Saemangeum and drying on air. The main results are summarized as follows : 1) The maximum and minimum void ratio lines follow similar trends. 2) Maximum and minimum void ratios are established at 20~30% fines content. 3) As confining pressures and overconsolidation ratio are increased, the resistance to liquefaction are increased. 4) Instability friction angles are increased with increasing initial relative density. 5) The resistance to liquefaction are decreased with increasing effective stress ratio.

• Journal of the Korean Geosynthetics Society
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• v.10 no.4
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• pp.19-28
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• 2011

This paper presents the results of an investigation into the effect of cyclic wetting-drying on the compressive strength characteristics of decomposed granite soils. A series of plane strain compression (PSC) tests were performed on test specimens with varying fine contents under different wetting-drying cycles to investigate the change in compressive strength under the process of wetting-drying cycles. The effect of wetting-drying cycles on the structural particle rearrangement at a micro-scale level was also examined using scanning electron microscope (SEM) tests. It was shown that the soil containing larger fines showed more significant decrease in compressive strength compared with the soils with less fines. Also found was that the wetting-drying cycle did not have significant effect on the particle arrangement.