• The Journal of Engineering Geology
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• v.19 no.4
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• pp.501-508
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• 2009

This study aims to clarify the characteristics of the physical and mechanical properties of soil-slope failure of Okcheon metamorphic zone. Soil samples were collected from 35 collapsed and uncollapsed artificial slopes along national roads. A series of laboratory experiments was carried out to examine physical and mechanical properties of soils and rocks. The results show that failure slopes have weakness of failure at 0.75 of AMI or higher, 32% of liquid limit or higher, and 31% of saturated moisture content or higher. The plastic index of failure slopes is correlated to wet density and saturated density. It turned out that failure could easily happen according to a high plastic index even if the void ratio was low. The greater the contents of bigger-sized soil, i.e. contents of sands and gravels rather than of clays, is the greater the chance to fail at the slope.

• The Journal of Engineering Geology
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• v.13 no.3
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• pp.335-344
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• 2003

This study is focused to the physical and shear strength properties of the weathered limestone soils distributed in Changsung and Hwasun area, Chonnam province. Disturbed soil was used as soil samples. To grasp the physical and shear strength properties of weathered limestone soil, specific gravity test, atterberg limit, grain size distribution and direct shear test were conducted in the laboratory. The physical and shear strength properties of the weathered limestone soil in the study areas are as follows. The range of specific gravity (Gs) is 2.78 to 2.80, liquid limits (LL) 37 to 38 (%), plasticity index (PI) 13.7 to 15.4, and soil classification CL. The range of strength parameters by direct shear test (vd, $1.5t/\textrm{m}^3$) is 3.07 to 4.4 ($t/\textrm{m}^2$) of cohesion and 34.8 to $42.4^{\circ}$ of internal friction angle in unsaturated soils. As a result of comparing with the weathered granite soils (Yang, 1997: Mun, 1998: Park, 1998), it is considered that physical properties of the weathered limestone soils in this study are different from the weathered granite soils. On the other hand, internal friction angle of shear parameters is found to be similar.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.4
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• pp.199-208
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• 1993

Using several soil parameters which are obtained from the PI-experimental formulas and the back analysis method, the elastic analysis, the elasto-plastic analysis and the elasto-viscoplastic analysis for soil deformation are executed. Comparing the results with those of consolidation test, the indirect estimation method for soil parameters and the suitability of constitutive models are studied. The elastic analysis using back analysis result and the elasto-plastic analysis using the perconsolidation test. The elasto-viscoplastic analysis disagrees with the results of meability coefficient obtained from back analysis are the nearest to the results of the consolidation test. It is inferred that elasto-viscoplastic model is not adequate to the soil of which plasticity index is low.

• Proceedings of the Korean Geotechical Society Conference
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• 1988.06c
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• pp.3-67
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• 1988

Model studies on the response of homgeneous earth embankment dams subjected to strike-slip fault movement have been penomed via centrifuge and finite element analysis. The centrifuge model tests have shown that crack development in earth embankment experiences two major patters: shear failure deep inside the embankment and tension failure near the surface. The shear rupture zone develops from the base level and propagates upward continuously in the transverse direction but allows no open leakage chnnel. The open tensile cracks develop near the surface of the embankment, but they disappear deep in the embankment. The functional relationship has been developed based on the results of the centrifuge model tests incorporating tile variables of amount of fault movement, embankment geometry, and crack propagation extent in earth des. This set of information can be used as a guide line to evaluate a "transient" safety of the duaged embankment subjected to strike-slip fault movement. The finite element analysis has supplemented the additional expluations on crack development behavior identified from the results of the centrifuge model tests. The bounding surface time-independent plasticity soil model was employed in the numerical analysis. Due to the assumption of continuum in the current version of the 3-D FEM code, the prediction of the soil structure response beyond the failure condition was not quantitatively accurate. However, the fundamental mechanism of crack development was qualitatively evaluated based on the stress analysis for the deformed soil elements of the damaged earth embankment. The tensile failure zone is identified when the minor principal stress of the deformed soil elements less than zero. The shear failure zone is identified when the stress state of the deformed soil elements is at the point where the critical state line intersects the bounding surface.g surface.

• Geotechnical Engineering
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• v.5 no.4
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• pp.5-16
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• 1989

This paper statistically analyses the freezing soil by frost group and frost depth in Korea with data from soil testing in the Korea National Housing Corporation, the climate data provided by the Central Weather Office and the data on the frost depth from the National Construction Laboratory Institute. In this paper, freezing variable are analysed such as percentage finer than 0.02 m by weight, plasticity index, freezing index, water contents of soil and frost depth etc‥‥ The result of the analysis is as follows. 1) The frost depth of Korea depends on the properties of soil rather thank the characte fistic of area. 2) The distribution map of design freezing index in 57 cities is drawn up with the maxi- mum freezing index, during past 14 years, calculated by the average of the air temperature observed four times(03 : 00.09 00, 15 : 00, 21 : 00) a day. 3) By correcting the OLS line estimated from the relationship between freezing index and frost depth, a method of utlizing the line with the upper confidence limit of 99.9% int-distribution as predicted maximum frost depth is newly introduced.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3C
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• pp.93-102
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• 2011

Most experimental studies on soil liquefaction are related to clean sands. However, soils in the field or reclaimed grounds commonly contain some amounts of silt and clay rather than clean sand only. Many researchers investigated the effect of fine contents on liquefaction resistance and mainly used non-plastic fines such as silts. In this study, 10% of plastic fines with various plasticity index (PI) such as 8, 18, 50, and 377 were mixed with wet Nakdong River sand and then loose, medium, and dense specimens were prepared by undercompaction method. A series of undrained cyclic triaxial tests were carried out by applying three different cyclic stress ratios. As a result, the liquefaction resistance tended to decrease as a PI of fines in the specimens with equal fine content increased. On the other hand, the difference between loose specimens with low and high plasticity fines was not clearly observed in terms of liquefaction resistance. However, in the case of dense specimens, liquefaction resistance decreased up to 40% as a plasticity of fines increased.

• Conservation Science in Museum
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• v.25
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• pp.35-50
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• 2021

This study analyzed the basic properties of soil material gathered around Maegok-dong in Gwangju, Gyeonggi-do Province (hereafter, "Maegok soil") and the physicochemical changes in the Maegok soil resulting from the addition of other clay materials in order to present scientific information about the properties of clay available for pottery production. Gravel, coarse sand, and fine sand account for 73% of the total mass of the Maegok soil. Therefore, it required refinement through sifting in order to serve in pottery clay. After sifting, the amount of silt and clay in the soil increased to 95% of the total mass. However, since it lacked plasticity and viscosity, buncheong soil was added. When it was mixed with bungcheong soil at a ratio of 7:3, Maegok soil improved as pottery clay as its viscosity increased, demonstrating compositional properties appropriate for ceramic clay even after firing. Further, its water-absorption rate was decreased to 0.40. This means that soil gathered from anywhere can be used for pottery-making by refining its original properties and through mixture with clay with specific components which help the pottery maintain its shape even after firing.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.68-79
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• 2018

An examination of the characteristics of the ground material in is very important in a ground investigation. Casagrande classified soil using the material properties of soils. The liquid-plastic limit test is useful for obtaining basic information of soil, and is an effective method for classifying silt and clay, as well as the material properties, such as shear strength, shrinkage, and expansion. Unlike the liquid limit test, the plasticity limit test is due to the ambiguity of the test procedure. Many geotechnical engineers and scholars have questioned the test results. In this study, a new plasticity limit method was used to compare with the thread rolling method with kaolinite, ilite and bentonite at a certain ratio, and samples were collected from the west coast of Korea. As a result of the comparison, the test value of the new test method showed high reproducibility because the error range of the test value of the conventional thread rolling test was only 10% but the error range of the new test values decreased to 2%. The difference in the slope of the existing plasticity test values was 0.1519 ~ 0.1925, and the results of the test were similar or coincided with each other. Aone - point method was proposed to make it easier to apply the new test method.

• Journal of the Korean Geotechnical Society
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• v.30 no.11
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• pp.25-37
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• 2014

Clay or sand does not exist alone but various sizes of soil are mixed in the field. In this study, the effect of water content on large deformation of such mixed soils is studied by using soil column tests and a particle method. A soil column with 7 cm in diameter and 13 cm in height, which was made out of kaolinite with sand content of 0, 10, 25, or 50%, was tested for large deformation. Its deformation was monitored with time. While increasing its water content from 40, 60, to 80%, a total of 12 types of soil column tests were carried out. The particle method simulated their deformation with time. A maximum plastic shear modulus, which was a function of undrained shear strength and plasticity index for soils with different water contents, was associated with soil viscosity to simulate large deformation of soil column. When a sand content of soil column was constant, the deformation of soil column increased with increasing water content. When a water content of soil column was constant, large deformation occurred with increasing the sand content. The maximum deformation, which was 22 cm in diameter, was observed in the case of water content of 80% and sand content of 50%. The particle method was able to relatively well simulate such large deformation and stress change of soils.

• Journal of Korean Society on Water Environment
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• v.25 no.3
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• pp.404-410
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• 2009

In this study, research for physical and chemical characteristics were conducted through analysis of sediments, grading and heavy metals (e.g., Mn, Cu, Cd, Zn and Pb ) in sewers which are classified by drainage types. After that, cement solidification and yellow soil calcinations made heavy metals stabilized and then, ways of recycling it were examined. The grain size distribution of all sediments was relative graded. When evaluating heavy metal pollution through index of geoaccumulation (Igeo), Cu showed moderately pollution or strong pollution in forest and street site and Zn was assessed by moderately pollution in military, residential, and street site. Analysis of Pearson Correlation coefficient of heavy metal indicated that all items in street site have tight relationship respectively. Especially, Cd-Zn, Cu-Pb, Cu-Mn, and Pb-Mn have relationship at 99% confidence intervals in statistical analysis. Recycling it with cement solidification was satisfied with compressive strength standard under 55% deposit contents and Zn, Pb, Mn were stabilized effectively. If time and temperature plasticity and compressive strength would be standard, it is revealed that yellow soil calcinations is valuable aggregate when it has 50-60 Wt% contents. When considering economic feasibility and stabilization of heavy metals, cement solidification would be more appropriate than yellow soil calcinations as solution to recycling.