• 한국토양비료학회지
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• 제44권5호
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• pp.944-958
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• 2011

Soil hydraulic properties such as hydraulic conductivity or water retention which are costly to measure can be indirectly generated by soil pedotransfer function (PTF) using easily obtainable soil data. The field soil structure description which is routinely recorded could also be used in PTF as an input to reduce the uncertainty. The purposes of this study were to use qualitative morphological soil structure descriptions and soil structural index into PTF and to evaluate their contribution in the prediction of soil hydraulic properties. We transformed categorical morphological descriptions of soil structure into quantitative values using categorical principal component analysis (CATPCA). This approach was tested with a large data set from the US National Pedon Characterization database with the aid of a categorical regression tree analysis. Six different PTFs were used to predict the saturated hydraulic conductivity and those results were averaged to quantify the uncertainty. Quantified morphological description was successively used in multiple linear regression approach to predict the averaged ensemble saturated conductivity. The selected stepwise regression model with only the transformed morphological variables and structural index as predictors predicted the $K_{sat}$ with $r^2$ = 0.48 (p = 0.018), indicating the feasibility of CATPCA approach. In a regression tree analysis, soil structure index and soil texture turned out to be important factors in the prediction of the hydraulic properties. Among structural descriptions size class turned out to be an important grouping parameter in the regression tree. Bulk density, clay content, W33 and structural index explained clusters selected by a two step clustering technique, implying the morphologically described soil structural features are closely related to soil physical as well as hydraulic properties. Although this study provided relatively new method which related soil structure description to soil structure index, the same approach should be tested using a datasets containing the actual measurement of hydraulic properties. More insight on the predictive power of soil structure index to estimate hydraulic properties would be achieved by considering measured the saturated hydraulic conductivity and the soil water retention.

• 한국토양비료학회지
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• 제7권3호
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• pp.127-135
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• 1974

The samples were taken from the following localities previously classified as "Akiochi" area: Yangpyung, Puchun, and Pyungtaik, all of Kyonggi-do province. Five soil profiles were described in the field, and taken to the laboratory for physical and chemical analysis and mineralogical analysis by X-ray diffraction. The predominant clay minerals consist mainly of illite, vermiculite, chlorites and intergrade with vermiculite, and kaolinite. Illite or mica was found present in all samples and in all horizons. This was identified by the 9.83 to $10{\AA}$ (0.01) and $3.32{\AA}$ (003) basal reflections, Interhorizontal variations in mineral content and crystallinity are illustrated in their respective Xray diffractogram. Comparing the peak intensity, of the $14{\AA}$, $10{\AA}$ and $7{\AA}$ indicated the degree of weathering from the surface to the lower horizons. In general, the weathering of illite on the surface produced less pronounced $10{\AA}$ and $14{\AA}$ peak as compared to the lower horizons. The same may be said with kaolinite. On K-saturation, the $14{\AA}$ peak broadening on the low angle side was observed. This is interpreted to be due to chlorization. Heat treament from $100^{\circ}C$, $200^{\circ}C$, $400^{\circ}C$, $600^{\circ}C$, and $800^{\circ}C$. caused significant changes in the different diffractograms. Heating caused collasped of the $14{\AA}$ to $10{\AA}$ and the appearance of scattered peaks between $10-14{\AA}$. This is interpreted to the presence of vermiculite chlorite intergradient. The complete collapse of the $14{\AA}$ at $800^{\circ}C$ to $10{\AA}$ with increased intensity was attributed to the preservce of vermiculite. The principal difference among the clay minerals in each horizon is the concomitant increase and decrease in intensity with depth of the $14{\AA}$, $10{\AA}$ and $7{\AA}$ diffraction spacings. Apparently the weathering of illite ($10{\AA}$) is resulting in the formation of vermiculite ($14{\AA}$) and the interstratified material being an intermediate stage and the beginning of the formation of vermiculite. Some broadening- in the 17 to $18{\AA}$ was observed in Puchun-1 Pyungtaik-1 and Pyungtaik-2 specially so in the lower horizon in the Ca or Mg-saturated sample. Heated treatment tend to shift this peak to $14{\AA}$ indicating the presence of regular layering of the interstratified complex. The high amount of extractable aluminum and iron coupled with low exchange capacity indicate that iron and aluminum plays an important role in the weathering of these soils and is responsible to the low exchange capacity, high acidity and high phosphate absorptive capacity. The results presented substantiated the weathering sequence of Jackson in that mica ${\rightarrow}$ vermiculite ${\rightarrow}$ chloritezed vermiculite ${\rightarrow}$ kaolinite.

• 한국지반공학회지:지반
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• 제5권2호
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• pp.45-56
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• 1989

정규압밀 점성토의 응력-변형 거동은 응력경로에 의하여 어떠한 영향을 받게 되는가를 규명하기 위하여, 실험실에서 인위적으로 압밀한 Kaolin정성토 공시체를 사용하여 현위치 응력상태인 연. 응 역상태로 압밀하고, 여러가지 서로 다른 응력경로를 따라 삼축추축 배수시험을 행하였다. 그 결과, 응력증가비가 특정한 값, 곧 임계응력증가비를 가질 때 응력-변형 거동은 거의 녹형의 형태로 나타나고, 그 이상이 되면 응력의 증가와 더불어 재료의 성질이 강화되는 변형경화 현상을 나타내고 있음을 알 수 있었다. 본 연구에서는, 이러한 변Wi초화 현상을 보이는 응력-변형 거동을 Drnevich의 쌍유선 함수의 개념을 적용하여 모델화 하였으며, 이를 축대칭 하중을 받고있는지반의 응력경로를 고려한 여밀침하 계산에 적용하는 방법을 제시하였다.

• 한국환경농학회지
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• 제5권2호
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• pp.135-140
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• 1986

K-bentonite를 K포화용액에서 이온교환법에 의해 제조했다. 모래땅, 황토, 산흙에서 K-bentonite 완효성의 효과를 비교 시험했는데, 특히 모래땅에서 그 효과가 컸다. 알타리무우 및 상치를 이용한 모래땅 재배에서 KCl시용구. 보다 K-bentonite구는 상치의 지상부의 생육과 알타리무우의 근부신장을 월등히 촉진 시켰다. 그러나 적정량을 관수하면서 모래, 산흙, 황토를 이용한 온실내 pot시험에서는 생육차를 발견할 수 없었다. K-bentonite는 무우 및 상치의 Vitamin C, Nitrate, Thiocyanate, Dry wt 등의 함량변화에 영향을 미치지 않았다. K-bentonite 실제 생산에 있어 문제점에 대해 논의하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.198-207
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• 2010

Many methods and techniques have been developed to obtain the accurate design parameters in soft soils. In particular, several researchers suggest the techniques to get the void ratio for understanding the soil behavior. The objective of this paper verifies the accuracy of the proposed analytical solution for determining the void ratio based on the elastic wave velocities. The paper covers the theories of Wood, Biot, Gassmann and Foti proposed chronological order. The total theory represents the wave propagation in fully saturated medium. To verify the proposed analytical solution, the laboratory and field tests are carried out. After measuring the elastic wave, the void ratios are assessed using proposed equation. The volume based void ratios are also obtained for comparing with the estimated value by several equations. The values estimated by volume, Gassmann and Biot are show good similarity. However, the void ratios based on Wood and Foti methods have a slightly different trend. This study suggests that the theories of Biot and Gassmann may be a useful equation for assessing the void ratio using elastic wave velocities in the field.

• Geomechanics and Engineering
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• 제8권5호
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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.

• 한국농공학회지
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• 제9권2호
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• pp.1296-1300
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• 1967

This study was made through the utilization of heavy soil taken from the experimental plot of heavy soil in Konkuk University, Changan-dong, Sungdong-ku, Seoul. The soil used in the experiment has the following physical characteristics: 1. The soil is very compact, impervious, and unfit for any plant growth, 2. For improvement of the soil, tile drainage practice has been employed, 3. According to the general theory of tile drainage, it is unnatural that the effect of drainage is actually observed in such a soil. The followings are the results of the experiment: 1. Water moved to crosswise when the plotted soil profile was not broke. In this case the upper sloped part was dry while the bottom part was moistned. The upper part of the tile was also moistned. 2. The crosswise movement of water was not observed in the artificially broken plot of subsoil. However, the water flow from the tile was observed for long period as a result of the increase of soil void, seepage, aeration, and water holding capacity. However, the water flow from the tile in the plot of unbroken subsoil was observed only in short period and soon the flow was stopped. 3. the distance between the tile laid in the heavy soil should not exceed 10m for the efficient drainage. 4. When the pF is 2.5 in the subsoil the moisture content was between 23.97% and 28.20%. However, when the water saturated in the subsoil the moisture content was between 34.30% and 22.10%. Accordingly without the higher pF than 2.5 the water can not be absorbed and therefore the drainage can not be occured.

• 한국농공학회지
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• 제40권5호
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• pp.37-42
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• 1998

This study was performed to evaluate the characteristics of volume change is unsaturated clayed soil. The medium-plastic clay was selected and compacted by 50% of Proctor standard compaction energy at 6% higher moisture content than its OMC. A series of isotropic compression tests and triaxial shear tests were performed. The results of the study are summarized as follows. At each matric suction, when the matric suction was increased, the yield stress was increased and slope of volume change was decreased. The more net mean stress was, the less the quantity of volume change was. In shear test, the volumetric strain was much rapidly changed in large matric than in low matric suctions. But the effect of matric suction to volume change disappeared under high net mean stress. At lower deviator stress the more matric suction was, the higher volume change was. But As the matric suction was increasing, the behavior of the unsaturated clayey soil was similar to that of saturated clayey soil. Volume change in the unsaturated clayey soil can be represented as a unique plane in three-dimensional space, which is the axes of net mean stress, matric suction and void ratio.

• 자원환경지질
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• 제32권1호
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• pp.43-51
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• 1999

In order to remediate hazardous waste site, a process of electrokinetically purging chemicals from saturated soil is examined by laboratory experiments. Electrokinetic soil remediation is one of the most promising soil decontamination processes that habe igh removal efficiency and time-effectiveness in low-permeability soils such as clay. Being combined with several mechanisms-electromigration, elec troosmosis, diffusion and electrolysis of water, electrokinetic soil processing can remove non-polar organics as well as ionic contaminants. The objectives of this study are; 1) the exploration of the feasibility of electrokinetic soil processing on the removal of heavy metals, 2) the investigation of applicability to the tailing-soils in aban doned mining area, 3) the examination of effects of soil pH and conductivity on the transport phenomena of elements in soils, and 4) the investigation of the applicability of the ionexchange membrance to the efficient collection of heavy metals removed from contaminated soils. With the result of this study, it is suggested that the removal efficiency is significantly influenced by applied voltage & current, type of purging solutions, soil pH, permeability and zeta potentials of soil. Although further study should be needed, it is possible to collect removed heavy metals with ion-exchange membrance in cathode compartment.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1992년도 폐기물 매립지의 공학적 특성과 개량기술
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• pp.33-66
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• 1992

Recently, waste landfills built on seashores have been increased because of the easy availability of broad area near the urban communities. To evaluate the performance of the marine clay landfill liner numerical contaminant transport analyses are performed by selecting the typical section of a waste landfill built on seashores and using hydraulic conductivity data obtained from the site. Also, the laboratory electrical resistivity test and the in-situ corrosion test are performed in order to analyze the influence of the soil and leachates composing the landfills on the construct ion materials. From the results of contaminant transport analyses, it is shown that the leachates can be migrated faster through narrow pervious channels than the wide homogeneous pervious tedium and the importance of good quality barriers to prevent the contaminant migration is recognized. In the laboratory electrical resistivity test all the earth materials except the cover soils saturated with distilled water have small resistivities, which shows a high potential of corrosivity of soils composing landfills. However, the degree of corrosion of specimens buried in the landfills was not so severe except the zinc and carbon steel specimens. This apparently conflict results present the necessity of the investigation of other major factors and the long term in-situ corrosion test.