• Korean Journal of Soil Science and Fertilizer
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• v.48 no.5
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• pp.564-569
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• 2015

In highland crop fields, saprolite is piled up approximately every three years as deep much as 20 to 30 cm because farmers expect that adding new materials may improve productivity and mitigate hazards by continuous cultivation of a single crop. Piling saprolite, however, has been reported to induce poor soil drainage. Effects of deep ploughing with a spading machine and an excavator were studied in sites located in Daekwanryeong-myeon, Pyeongchang in which soil physical properties were deteriorated by piled saprolite. The soil made of parent material of Samgag series was piled up over surface soil of Haggog series naturally developed in the area. Carrot was cultivated in the field. Productivity and growth factors of carrot were compared among control and deep ploughing by a spading machine and an excavator. Effective soil depth extended to 60 cm or greater by 60 cm deep ploughing by an excavator or 50 cm deep ploughing by a spading machine. On the other hand, effective soil depth was within 50 cm at control plot. Productivity of carrot responded to amelioration of soil physical properties. The productivity was greater in deep ploughing treatments than that of control or 30 cm ploughing. It suggested that increased productivity by deep ploughing was mainly related to breaking plough pan which inhibited extension of rooting zone.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.5 no.6
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• pp.9-13
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• 2002

This study has been performed to investigate the physical and mechanical characteristics of compaction, volume change and compressive strength for reinforced soil mixed with cement. And confirm the reinforcing effects with admixture such as cement. To this end, a series of compaction test and compression test was conducted for clayey soil(CL) and cement reinforced soil. In order to determine proper moisture content and mixing ratio, pilot test was carried out for soil and cement reinforced soil. And the mixing ratio of cement admixture was fixed 3%, 6%, 9% and 12% by the weight of dry soil. As the experimental results, the maximum dry unit weight(${\gamma}_{dmax}$) was increased with the mixing ratio and then shown the peak at 10% reinforced soil, but the optimum moisture content(OMC) and the volume change was decreased with the ratio increase. And the compressive strength volume change was decreased with mixing ratio increased.

• Geomechanics and Engineering
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• v.7 no.6
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• pp.633-647
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• 2014

Biopolymers, polymers produced by living organisms, are used in various fields (e.g., medical, food, cosmetic, medicine) due to their beneficial properties. Recently, biopolymers have been used for control of soil erosion, stabilization of aggregate, and to enhance drilling. However, the inter-particle behavior of such polymers on soil behavior are poorly understood. In this study, an artificial biopolymer (${\beta}$-1,3/1,6-glucan) was used as an engineered soil additive for Korean residual soil (i.e., hwangtoh). The geotechnical behavior of the Korean residual soil, after treatment with ${\beta}$-1,3/1,6-glucan, were measured through a series of laboratory approaches and then analyzed. As the biopolymer content in soil increased, so did its compactibility, Atterberg limits, plasticity index, swelling index, and shear modulus. However, the treatment had no effect on the compressional stiffness of the residual soil, and the polymer induced bio-clogging of the soil's pore spaces while resulting in a decrease in hydraulic conductivity.

• Korean Journal of Environmental Agriculture
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• v.29 no.1
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• pp.27-32
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• 2010

This study was conducted to reclassify Anryong series based on the second edition of Soil Taxonomy and to discuss the formation of Anryong series distributed on the mountain foot slope. Morphological properties of typifying pedon of Anryong series were investigated and physico-chemical properties were analyzed according to Soil survey laboratory methods manual. The typifying pedon of Anryong series has brown (7.5YR 4/4) loam Ap horizon (0-22 cm), strong brown (7.5YR 4/6) cobbly clay loam BAt horizon (22-35 cm), strong brown (7.5YR 4/6) cobbly clay loam Bt1 horizon (35-55 cm), reddish brown (5YR 5/4) cobbly clay loam Bt2 horizon (55-82 cm), and brown (7.5YR 5/4) cobbly clay loam Bt3 horizon (82-120 cm). The typifying pedon has an argillic horizon from a depth of 22 to 120 cm and a base saturation (sum of cations) of less than 35% at 125 cm below the upper boundary of the argillic horizon. It can be classified as Ultisol, not as Alfisol. It has udic soil moisture regime, and can be classified as Udult. Also that meets the requirements of Typic Hapludults. It has 18-35% clay at the particle-size control section, and have mesic soil temperature regime. Therefore Anryong series can be classified as fine loamy, mesic family of Typic Hapludults, not as fine loamy, mesic family of Ultic Hapludalfs. Anryong series occur on mountain foot slope positions in colluvial materials derived from acid and intermediate crystalline rocks. They are developed as Ultisols with clay mineral weathering, translocation of clays to accumulate in an argillic horizon, and leaching of base-forming cations from the profile for relatively long periods under humid and temperate climates in Korea.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.6
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• pp.478-485
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• 2009

This study was conducted to reclassify Yongheung series based on the second edition of Soil Taxonomy and to discuss the formation of Yongheung series in Jeju Island. Morphological properties of typifying pedon of Yongheung series were investigated and physico-chemical properties were analyzed according to Soil Survey Laboratory Methods Manual. The typifying pedon contains 3.2~3.4% oxalate extractable (Al + 1/2 Fe), less than 85% phosphate retention, and higher bulk density than $0.90Mg\;m^{-3}$. That can not be classified as Andisol. But it has an argillic horizon from a depth of 15 to 150 cm and a base saturation (sum of cations) of less than 35% at 125 cm below the upper boundary of the argillic horizon. That can be classified as Ultisol, not as Andisol or Alfisol. The typifying pedon has 0.9 % or more organic carbon in the upper 15 cm of the argillic horizon and accordingly, can be classified as Humult. It has a clay distribution in which the percentage of clay does not decrese from its maximum amount by 20% or more within a depth of 150 cm from the mineral soil surface, and keys out as Palehumult. Also that meets the requirements of Typic Palehumult. That has 35 % or more clay at the particle-size control section and has mesic soil temperature regime. Yongheung series can be classified as fine, mixed, thermic family of Typic Palehumults, not as fine, mixed, thermic family of Typic Hapludalfs. Most soils distributed in the southern coastal areas in Jeju island which have a humid climate are developed as Andisols. But Yongheung series distributed in this areas and derived from mainly trachyte, trachytic andesite, and volcanic ash are developed as Ultisols.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.6
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• pp.1272-1278
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• 2011

This study was conducted to reclassify Cheongweon series based on the second edition of Soil Taxonomy and to discuss the formation of Cheongweon series distributed on broad continental alluvial plains. Morphological properties of typifying pedon of Cheongweon series were investigated and physico-chemical properties were analyzed according to Soil survey laboratory methods manual. The typifying pedon of Cheongweon series has dark grayish brown (2.5Y 4/2) silt loam Ap horizon (0~18 cm), dark grayish brown (2.5Y 4/2) silt loam BA horizon (18~30 cm), dark yellowish brown (10YR 4/6) silty clay loam Bt1 horizon (30~60 cm), strong brown (7.5YR 4/6) silty clay loam Bt2 horizon (60~91 cm), brown (10YR 4/4) silt loam BC horizon (91~104 cm), and mottled (7.5YR 4/6, and 7.5YR 5/2) silt loam C horizon (104~160 cm). The typifying pedon has an argillic horizon from a depth of 30 to 91 cm and a base saturation (sum of cations) of 35% or more at 125 cm below the upper boundary of the argillic horizon. It can be classified as Alfisol, not as Incceptisol. It has udic soil moisture regime, and can be classified as Udalf. Also that meets the requirements of Hapluadalf. It has anthraquic condition, and keys out as Anthraquic Hapludalf. That has fine silty textural family, and has mesic soil temperature regime. Therefore Cheongweon series can be classified as fine silty, mixed, mesic family of Anthraquic Hapludalfs, not as fine silty, mixed, mesic family of Fluvaquentic Epiaquepts.

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.1
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• pp.116-124
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• 2002

Natural resources fur the construction materials such as good soil, sand, and coarse aggregates have been encountered to be short due to excessive use by human. Even though some soil has been found to be unsuitable for construction materials, soil with reinforcement can naturally be an answer to these alternatives. According to recently published papers on fiber mixed soil, fiber mixed with soil can improve shear strength, compressive strength and post-peak load strength retention. In this study, a series of tests were performed to clarify the characteristics of fiber mixed soil and to give basic data for design and construction and their engineering properties, that is, unconfined compressive strength, splitting tensile strength, shear strength, crack by drying, freeze-thaw, creep and Poisson\`s ratio, were investigated and analyzed. It has been shown that fiber mixed soil is one of good alternatives fur the civil and building construction materials.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1047-1054
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• 2005

The purpose of this study is the understanding to changes in the characteristic of soil structure and classification, atterberg limits, undrained shear strength and consolidation of clayey soil dependent on pH of soil pore water. A series of tests including consistency tests, uniaxial compressive tests, vane tests and oedometer tests are performed on. The test results indicated that pH changes in the soil pH resulted in changes in the soil structure and classification, stress-strain behavior. Specially, when pH is conditioned to 7, liquid limit, undrained shear strength and preconsolidation pressure are the largest.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1614-1622
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• 2008

A series of three-dimensional numerical modelling have been conducted to clarify the behaviour of multi-pressurised soil nails with high strength steel pipes. In this study, the soil non-linearity, the soil-nail interaction and staged construction are considered. It has been found that pressurised soil nails can reduce lateral ground movement by 14-21% compared to general soil nails with very low pressure. In addition, ground settlement was reduced when using multi-pressurised soil nails. The pressurised soil nail may result in an increase in the surcharge loading on the ground surface.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.1
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• pp.1-9
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• 1993

A study was carried out to investigate the genesis and mineralogical characteristics of clay minerals in three different types of soil derived from the gray shale distributed in Kyeongbuk Province in Korea. The soils have been developed from parent materials of residuum (Daegu series, Sirye series), colluvium(Banho series), and alluvium (Bigog series) of the same origin of parent rock with a topographical sequence. The investigation mainly focussed on the mineralogical aspects of primary minerals of asnd and silt fractions, identification and quantification of clay minerals, and characterization of hydroxy-interlayered mineral (HIM) along with their chemical composition. The identification was done through analyses of chemical, X-ray diffraction, and thermal methods. The major clay minerals in the soils are illite, vermiculite, kaolin and HIM, while chlorite and mixed layer minerals such as illite/chlorite and illite/vermiculite were coexisted as a subsidiary minerals. The distribution of clay minerals, however, varies according to the location and types of parent material. In the soils derived from the parent material of residuum, the upper soil (Daegu series) shows higher of 2:1 type minerals such as illite, vermiculite, and HIM than 1:1 type mineral rich in the lower soil(Sirye series). Soils developed from the parent material of colluvium and alluvium were high in illlte and mixed layer minerals, but low in HIM compared with the residual soils. The predominant weathering sequence of the clay minerals in each soil could be inferred as follows according to the minerlogical distribution and quantification of clay minerals : Daegu series, illite ${\rightarrow}$ vermiculite ${\rightarrow}$ HIM ; Sirye series, vermiculite ${\rightarrow}$ kaolin minerals ; Banho sereies and Bigog series, illite ${\rightarrow}$ illlte/vermiculite and/or illite/chlorlte mixed layer ${\rightarrow}$ vermiculite.