• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.265-272
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• 2000

This study introduces the current theory of the SWCC and tries to verify the theory by performing laboratory tests for the local soils of Korea. First, the SWCCs of Poi-dong soil and Shinnae-dong soil, the most typical weathered residual soils in Korea, were experimentally obtained and the results were compared among others. Second, a SWCC model for deformable soils was proposed. For deformable soils, which show huge volume change during desaturation, the volume change behavior should be considered, and the SWCC should be expressed as a function of void ratio as well as suction.

• Journal of the Korean GEO-environmental Society
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• v.10 no.3
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• pp.13-20
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• 2009

Generally, soil is regarded as fully saturated in Geotechnical Engineering and under ground structure design. Because it is in convenience and safety. But soils treated in field are almost in unsaturated state. Design in unsaturated state is difficult comparing with saturated soil. In unsaturated soil mechanics, parameters are usually not constant unlike saturated soil mechanics. Additionally lab or field tests in unsaturated soil mechanics are required more cost, time and theoretical difficulty. One of essential requisites for examination about unsaturated soil is Soil-Water Characteristic Curve (SWCC). It show the relation between soil suction and soil water content. Through many studies in and out of country, computation and testing methods for SWCC were introduced. But in this the country, most soil is granite soil that is widely spread in Korea. And the studies for granite soil's SWCC are not enough yet. In this paper, through studying for existing proposal methods about computation SWCC and collection data for domestic granite soils, It was determined the suitable method for domestic granite soils, and computed each granite soil's SWCC. The purpose of this paper is establishing database for domestic granite soil's SWCC as each region to convenience for applying to actual affairs. For this, studying about existing proposal methods for SWCC was performed and a computer program Soil-Vision is used. Furthermore for verification theoretical and testing methods were also performed.

• Journal of the Korean GEO-environmental Society
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• v.12 no.2
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• pp.23-33
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• 2011

In this paper, we got soil-water characteristic curve(SWCC) of Nak-Dong River's sand respectively as relative density 40%, 60%, 80% and content of silt 0%, 10%, 20%, 30%. As a result, the more the sand densify in the same silt content and the more the sand has silt in the same relative density, the change of volume water content was decreased. we have known effect of silt contents for SWCC and verified existing empirical formula of SWCC. As experiment results of soil-water characteristic curves compared to the empirical solutions, the results of van Genuchten(1980) and Fredlund & Xing(1994) were well-matched showing S type curves with experiment results. Especially the empirical solution of Fredlund & Xing showed almost same results of the coefficient of correlation($R^2$) equal to 0.99.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.28-33
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• 2006

Shallow failures of slopes in weathered soils are caused by infiltration due to prolonged rainfall. These failures are mainly triggered by the deepening of the wetting band accompanied by a decrease in suction induced by the water infiltration. In this paper, hysteresis on soil-water characteristic curve(SWCC) of granite and gneiss weathered soils are investigated using transient flow analysis respectively. Each case was subjected to artificial rainfall intensities and time duration depending on the laboratory-based drying and wetting processes. The results show that the unsaturated seepage on weathered slopes are very much affected by the initial suction of soils and unsaturated permeability of the soils. In addition, a granite weathered soil has a lower air-entry value, residual matric suction, and wetting front suction and less hysteresis loop than a gneiss weathered soil.

• Geomechanics and Engineering
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• v.8 no.5
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• pp.687-706
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• 2015

Methods commonly used to evaluate the improvement of lime-treated expansive soil include swelling characteristics and unconfined compressive strength. In the field, lime-treated expansive soils are in compacted unsaturated state. Soil water characteristic curves (SWCCs) represent a key parameter to interpret and describe the behavior of unsaturated expansive soil. This paper investigates the use of SWCC as a technique to evaluate improvements acquired by expansive soil after lime treatment. Three different lime contents were considered 2%, 4% and 6% by dry weight of clay. Series of tests were performed to determine the SWCC for the different lime content under curing periods of 7 and 28 day. Correlations between key features of the soil water characteristic curves of lime treated expansive soils and basic engineering behavior such as swelling characteristics and unconfined compression strength were established. Test results revealed that initial slope ($S_1$), saturated water content ($w_{sat}$), and air entry value (AEV) play an important role in reflecting improvement in engineering behavior achieved by lime treatment.

• Journal of the Korean Geotechnical Society
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• v.35 no.9
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• pp.5-13
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• 2019

The soil-water characteristic curve (SWCC) plays an important role in determining the soil suction parameters required to predict the seepage or shear behaviors of unsaturated soils. In addition, path dependency of the SWCC affects the mechanical and hydrologic behaviors. In general, there is a disadvantage that it takes a long time to measure both the drying and wetting paths of the SWCC by a stepwise pressurization method. Thus, the continuous pressurization method as an improved testing method for the SWCC was suggested, and the testing time for two paths of the SWCC was significantly shorter than the conventional methods. For the applicability evaluation of this method, the results of the SWCC obtained by the stepwise pressurization method and the evaporation method in this study were compared to the result obtained from this method. As a result, it was found that the difference among three methods was negligible, and the testing time of the continuous pressurization method was greatly decreased. Therefore, it can be said that it is possible to quickly and accurately measure the SWCC under various conditions by the continuous pressurization method.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5C
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• pp.191-198
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• 2009

It has been reported in Korea that surface slope failures in weathered soil are mainly caused by downward infiltration due to rainfall. These failures are triggered by the deepening of the wetting band in soils accompanied by a decrease in matric suction induced by the water infiltration. So, a need exists that these trends of wetting path in gneiss weathered soils, which is commonly found in Korea, are assessed by phenomenological approach. In this paper, numerical analyses of unsaturated soil slope under rainfall conditions are presented based on the wetting path soil-water characteristic curve in the laboratory. As the field SWCC matches well with the wetting path of the laboratory SWCC from the literatures, it seems reasonable to adopt the laboratory wetting SWCC as an upper boundary condition in the assessment of unsaturated slope instability.

• 한국도로학회:학술대회논문집
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• 2011.03a
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• pp.9-14
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• 2011

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.2
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• pp.515-524
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• 2015

The number of occurrence of differential settlement and track irregularity at track transition zone recently comes to increase, which leads to frequent maintenance activities that have an impact on train operation. Such track transition zone damages are attributed to the change of mechanical properties of fill materials due to environmental factors such as rainfall and freeze, and thaw. Consequently, this study attempts to establish the soil water characteristic curve (SWCC) of fill materials, and conduct seepage analysis to assess the distribution of degree of saturation (DOS) for track transition zone in case of rainfall. The SWCC of fill materials was successfully obtained using filter paper test method. The results of seepage analysis revealed that rainfall intensity, the slope of backfill, backfill condition (fill or cut), and SWCC are significantly influential in controlling the distribution of DOS.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.1D
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• pp.83-90
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• 2011

A need still exists that the unsaturated condition is to be considered when evaluating the infiltration and drainage capacity for compacted geomaterials in road foundation or embankments. For this reason, numerical analysis were used to analyze the time-dependent unsaturated infiltration and drainage condition depending on various geomaterial types. Therefore, laboratory data from the soil-water characteristic curve tests on geomaterials were adopted from previous studies. In addition, the unsaturated permeability was estimated using SWCC. Then the infiltration and drainage performance of unsaturated compacted soils were evaluated under various conditions based on the proposed method. The results demonstrated that the effect of initial suction and SWCC path on each material could be substantial and the proper application on analysis is very important to enhance the prediction on each capacity.