• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.103-110
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• 2006

When enforced earth is used for the retain wall and four walls, the most important thing would be how to maximize the land utilization. Accordingly, in case of enforced earth, we pile up the minimal height of earth$(20\sim30cm)$ and harden the earth using a static dynamic hardening machine. In this paper, we tried to analyze and. compare the stress transformation characteristics of reinforced weathered granite soil. with geosynthetics when repetitive load is added to the enforced earth structure and when static load is added. The purposes of the study are as follows; 1) To compare and analyze non reinforced weathered granite soil and reinforced weathered granite. soil by executing a unconsolidated-undrained triaxial compression tests. 2) To identify the strength characteristics of weathered granite soil reinforced with geotextile due to the repetitive dynamic loads through comparison of the stress due to the static load and the repetitive dynamic loads.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1124-1131
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• 2008

Thanks to a new in-situ seismic probe, using bender elements and penetration scheme, a simple linear relationship between undrained shear strength(Cu) and shear wave velocity(Vs) was obtained. This priceless relationship is worthy to be illuminated further in ideal laboratory environment. To avoid sampling disturbance effect, special consolidation cylinders were used to make normally consolidated specimens from kaolinite suspension. The undrained shear strengths of the specimens were measured using unconsolidated undrained triaxial compression tests. Also shear wave velocity measurements were performedprior to shearing the same specimens, using the bender elements installed in the base pedestal and the top cap of the triaxial compression cell. The Cu-Vs relationship is fairly linear and supports the linear trend of clayey silt obtained using field testing. Also the classic density-shear modulus relationship for soft clay proposed by Hardin and Black(1969) was once more verified hereby.

• Journal of Navigation and Port Research
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• v.33 no.2
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• pp.119-125
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• 2009

The effect of plastic board drains (PBDs)on ground improvement was checked out considering three crucial factors: ground settlement, undrained shear strength, and residual water head. First, the settlement analysis including initial settlement induced by reclamation of sand mat was conducted by back calculation analysis with measured data. Its result showed toot the PBDs used for this site worked well on improving soft ground. Secondly, the undrained shear strength was investigated by laboratory and in-situ tests including unconsolidated-undrained triaxial compression (UU) tests, unconfined compression tests, in-situ vane tests, and cone penetration tests. From the test results, they showed that the undrained shear strength of the improved ground by PBDs was significantly increased as well as the strength increasing ratio especially $10{\sim}15m$ below the ground surface on site. Thirdly, the residual water head measurement from the in situ dissipation test was found the same as the static water head, which indicated primary consolidation was completed and the effect of soil improvement with PBDs can be confirmed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.3
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• pp.429-438
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• 2018

Cone and T-bar penetrometers have been frequently used to estimate the undrained shear strength of clay. For small-size model tests, miniature penetrometers should be used but their correlation factors have not been well published. In this study, a testing setup was developed to derive empirical factors of the miniature cone and T-bar penetrometers. A 350mm-diameter chamber and kaolin clay were utilized to prepare soil specimens consolidated under four different pre-consolidation pressures controlling undrained shear strength. Two miniature cones with two diameters of 10-mm and 16-mm and a T-bar penetrometer with 10-mm diameter were used to investigate boundary effect, penetration rate effect, and diameter and shape effect. Unconsolidated-undrained triaxial tests were carried out with samples taken from the specimens to measure undrained shear strength. Finally, empirical factors for the penetrometers were constructed to correlate tip resistance to undrained shear strength.

• Proceedings of the Korean Geotechical Society Conference
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• 1992.10a
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• pp.145-148
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• 1992

This paper reports the application of field tests to weak ground. In this study, field and laboratory tests were performed in the west seashore of KOREA(Ildo, Sore, Kunsan, Youngam). Applied tests are standard penetration test, cone penetration test, dilatometer test, field vane test, unconsolidated undrained test, oedometer test and other fundametal material properties tests. The results of in-situ test are used to estimate soil types and undrained shear strengths of five clay local deposits. SPT results showed low reliability and FVT war also demonstrated the best field test to weak clayey deposits.

• Journal of the Korean Geotechnical Society
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• v.22 no.7
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• pp.13-21
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• 2006

When enforced earth is used for the retain wall and four walls, the most important thing would be how to maximize the land utilization. Accordingly, in case of enforced earth, we pile up the minimal height of earth ($20{\sim}50\;cm$) and harden the earth using a static dynamic hardening machine. In this paper, we tried to analyze and compare the stress transformation characteristics of reinforced weathered granite soil with geosynthetics when repetitive load is added to the enforced earth structure and when static load is added. The result is that the cohesion component of the strength increased greatly and the friction component decreased slightly.

• Geomechanics and Engineering
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• v.37 no.4
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• pp.419-429
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• 2024

The primary goal was to assess how the addition of cement dust, a byproduct known to be harmful, could be used to stabilize clay. Various percentages of cement dust were added to soil samples, which were then subjected to triaxial testing at different rates of strain using an unconsolidated undrained triaxial machine. Six different rates of strain were applied to analyze the response of the clay under different conditions, resulting in 216 triaxial sample tests. As the percentage of cement dust in the clay samples increased, there was a noticeable increase in the strength properties of the clay, indicating a positive effect of cement dust on the clay's strength characteristics. Higher rates of strain during testing led to increased strength properties of the clay. Varying cement dust content influenced the impact of increasing the rate of strain on the clay's strength properties. Higher cement dust content reduced the sensitivity of the clay to changes in strain rate, indicating that the clay became less responsive to changes in strain rate as cement dust content increased. Potential for Clay Stabilization Cement dust proved the potential to enhance the strength properties of clay, indicating its potential utility in clay stabilization applications. Both higher percentages of cement dust and higher rates of strain were found to increase the clay's strength. It's essential to consider both the percentage of cement dust and the rate of strain when assessing the strength properties of clay in practical applications.

• Journal of the Korean Geotechnical Society
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• v.34 no.2
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• pp.5-17
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• 2018

In this study, the in-situ stress, strength and stress-strain characteristics with shear parameters (UU, CU, ${\bar{CU}}$) are analytically evaluated and the stability analyses are carried out under loading/unloading conditions. The in-situ stress and the stress-strain behaviour may become different according to input shear parameters in finite element analyses with construction step, Especially, if the internal friction angle in Mohr-Coulomb model is set to zero, the in-situ stress and the stress-strain behaviour might not be properly predicted. The results from CU parameter of total stress analysis have no significant difference with the results from CU of effective stress analysis. Therefore, in the numerical analysis for soft ground, CU parameters can be applied to predict in-situ stress and stress-strain behaviors. In addition, the calculation method was proposed to determine the shear parameter of Mohr-Coulomb model, which is corresponding to the shear strength equivalent to that of in-situ soil.

• Geomechanics and Engineering
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• v.5 no.4
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• pp.331-342
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• 2013

The major factors that control the performance of reinforced soil structures is the interaction between the soil and the reinforcement. Thus it is necessary to obtain the accurate bond parameters to be used in the design of these structures. To evaluate the behavior of flyash + clay soil reinforced with a woven geotextile, 36 Unconsolidated-Undrained (UU) and 12 reinforced Consolidated-Undrainrained (CU) triaxial compression tests were conducted. The moisture content of soil during remolding, confining pressures and arrangement of geotextile layers were all varied so that the behavior of the sample could be examined. The stress strain patterns, drainage, modulus of deformation, effect of confinement pressures, effects of moisture content have been evaluated. The impact of moisture content in flyash + clay backfills on critical shear parameters was also studied to recommend placement moisture for compaction to MDD. The results indicate that geotextile reinforced flyash + clay backfill might be a viable alternative in reinforced soil structures if good-quality granular backfill material is not readily available.

• Journal of the Korean GEO-environmental Society
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• v.11 no.12
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• pp.57-62
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• 2010

In this study, the effect of different silt contents on the shear characteristics of silty sands was evaluated. Two series of triaxial compression tests were performed on the cylindrical specimens of compacted Nakdong river sand with 10% and 30% silt contents under unconsolidated undrained condition. All identical specimens were prepared to compact with same initial water content for five layers and saturated using control panel and then sheared under initial effective confining pressure, 100 to 400kPa. All specimens exhibited a strain softening tendency after failure in stress-strain curves and deviator stresses of specimens with 10% silt content were greater than those of specimens with 30% silt content. Pore water pressures of specimens with 10% silt content were observed negative(i.e. swelling) due to increasing void ratio after failure but those of specimens with 30% silt content were shown only positive. The behavior of compacted cylindrical specimens with low silt content was more dilative than that of high silt content. Peak deviator stresses decreased as increasing silt content and peak pore water pressures increased as increasing silt content.