• Title/Summary/Keyword: sandy soils

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Frost Heaving Pressure Characteristics of Frozen soils with Frost-Susceptibility and Degree of Saturation (흙의 동상민감성과 포화도를 고려한 동상팽창압 특성)

  • 신은철;박정준;김종인
    • Proceedings of the Korean Geotechical Society Conference
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    • 2002.03a
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    • pp.329-336
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    • 2002
  • The earth structures and in-ground LNG tank, and buildings can be constructed with using artificial freezing method on the reclaimed land. In this study, upon freezing a saturated soil in a closed-system from the top, a considerable pressure was developed. The pressure is the result of the surface energy of a curved ice-water interface. The most significant of these parameters will have the greatest effect on the classification. In order to establish frost-susceptibility criteria based on frost heaving expansion pressure, more soils have to be tested. This study was initiated to investigate the soils frost heaving expansion pressure and moisture characteristics resulting from freezing and freezing-thawing cycle process. Weathered granite soils, sandy soil, sandy soil were used in the laboratory freezing test subjected to thermal gradients under closed- systems.

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Determination of Critical State Parameters in Sandy Soils from Standard Triaxial Testing (I) : Review and Application (표준삼축시험으로부터 사질토에서의 한계상태정수 결정에 관한 연구 (I) : 고찰 및 적용)

  • 조계춘
    • Journal of the Korean Geotechnical Society
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    • v.19 no.1
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    • pp.61-75
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    • 2003
  • Comprehensive review on the determination of critical state parameters in sandy soils from standard triaxial testing was performed to facilitate the application of critical state soil mechanics to the shear behavior of sandy soils. First, semantic differences in literature were clarified, inferring that critical state should be considered as the ultimate state at large deformation. Second, the characteristics of critical state parameters were discussed, and also the uniqueness of critical state line and the sensitivity of quasi-steady state condition were verified in relation to initial state, fabric, loading condition, and drainage condition. Third, as an example, the critical state soil mechanics was applied to evaluate the post-liquefaction shear strength, i.e. the reliable ultimate shear strength in liquified soils, in terms of critical state parameters.

Effect of Mycorrhizal Treatment on Growth of Acacia spp. On Sandy BRIS Soils in Peninsular Malaysia

  • Lee, Su See;Mansor, Patahayah;Koter, Rosdi;Lee, Don Koo
    • Journal of Korean Society of Forest Science
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    • v.95 no.5
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    • pp.516-523
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    • 2006
  • Marginal soils such as BRlS (Beach Ridges Interspersed with Swales) soils and ex-tin mining land make up approximately 0.5 million ha or about 2% of Malaysia's land area. In the coastal areas of the east coast of Peninsular Malaysia impoverished sandy BRIS dominates the landscape with most lying idle as there is no national management plan for their utilization. A field study was carried out to see whether mycorrhizal application had any effect on the growth of three exotic Acacia spp., i.e. Acacia auriculiformis, A. mangium and Acacia hybrid (A. auriculiformis ${\times}$ A. mangium) on BRIS soils. Two types of mycorrhizal inoculum, namely, a commercially available arbuscular mycorrhizal inoculum marketed as $MycoGold^{TM}$ and an indigenous ectomycorrhizal Tomentella sp. inoculum were tested. In the initial six months, height growth of all three tree species inoculated with the arbuscular mycorrhizal inoculum was significantly improved compared to the ectomycorrhizal inoculated and uninoculated control plants. The mycorrhizal effect was not evident thereafter and repeated application of the arbuscular mycorrhizal inoculum may be necessary for continued growth enhancement. Of the three species, A. mangium had the highest relative height growth rate over the 24 months on BRlS soils.

Experimental study of the compressive strength of chemically reinforced organic-sandy soil

  • Hu, Jun;Zhang, Lei;Wei, Hong;Du, Juan
    • Geomechanics and Engineering
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    • v.16 no.3
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    • pp.247-255
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    • 2018
  • Organic-sandy soils that contain abundant organic matters are widely encountered in estuarine cities. Due to the existence of organic matters, the strength and stiffness of this type of soil are significantly low. As a result, various geotechnical engineering problems such as difficulties in piling and constructing embankments and a lack of strength in poured concrete may occur in many estuarine sites; ground improvement such as cement treatment to this type of soils is needed. In this study, laboratory tests were performed to investigate the compressive strength of organic-sandy soil reinforced with primarily cement, in which the influences of several factors, namely types of cement and additional stabilizing agent, cement content, and water-cement ratio, were investigated and the orthogonal experimental design scheme was adopted. Based on the test results, an optimal permutation of these influencing factors is suggested for the reinforcement of organic-sandy soils, which can provide a useful reference for the relevant engineering practice.

Effect of Silty Soil Content on Shear Behavior of Sandy Soil (사질토의 전단거동에 실트 함량이 미치는 영향)

  • Yu, Jeongseok;Ahn, Kwangkuk;Kang, Hongsig
    • Journal of the Korean GEO-environmental Society
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    • v.21 no.11
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    • pp.21-26
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    • 2020
  • Natural soil is composed of particles of various sizes, and the shear behavior which is a kind of mechanical behavior of the soil is affected by the particle size distribution. In addition, since the natural soil contains a large mixture of coarse and fine grained soil, it is difficult to clearly understand the shear behavior of the soil. Therefore, a ring shear test was conducted on sandy soils that has various particle size distribution in order to identify the effect of the distribution on shear characteristics of soils. At this time, sand and silt were used for coarse and fine grained soils, respectively, to make sandy soils by changing the silt content. Also the water was supplied during the test to confirm shear characteristics of sandy soils with various particle size distributions. The result shows that the shear strength increases as the silt content increases, and the strength decreases as the silt content increases over the sand. Besides, residual shear strength gradually decreases because of the silt content when the water is supplied.

The Adsorption of N-methylcarbamate Insecticides on Soils (N-methlycarbamate 계(系) 살충제의 토양중(土壤中) 흡착(吸着))

  • Kim, Jang-Eok;Hong, Jong-Uck
    • Applied Biological Chemistry
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    • v.28 no.3
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    • pp.124-130
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    • 1985
  • Adsorption experiments of N-methylcarbamate insecticides on soils were carried out as a function of soil pH ana soil organic matter content with wet-and dry-land soils that were either oxidized or non-oxidized. The results obtained may be summarized as follows: The adsorption of N-methylcarbamate insecticides on soils was nearly leached to equilibrium after shaking for 12 hours. The adsorption of N-methylcarbamate insecticides was higher on sandy clay than sandy loam. The presence of organic matter in soil increased the adsorption of N-methrlcarbamate insecticides on soils. The mode of isothermal adsorption of N-methylcarbamate insecticides on soils was coincident with the Freundlich equation. Little effect of soil pH on the adsorption might be interpreted as that the adsorption was due to physical adsorption between N-methylcarbamate molecules and soil surface.

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The Strength Characteristics of Solidified Sandy Soils with Mixing Conditions (배합조건에 따른 고결사질토의 강도특성)

  • Yu, Chan;Chang, Pyung-Wuck;Lee, Chang-No;Roh, Gwang-Ha
    • Proceedings of the Korean Geotechical Society Conference
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    • 1999.02a
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    • pp.84-95
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    • 1999
  • Laboratory experiments were performed to evaluate the strength characteristics of solidified sandy soils by portland cement with mixing conditions. Factors considered in the experiments were the fine content(<#200, %), cement content(%) and water-cement ratio and unconfined compressive strength tests were performed on samples at 7 and 28 cured day. Results of tests showed that for a low cement content(7%∼10%) the fine content was very important while for a high cement content the water-cement ratio was very important. For 7%∼10% cement content, the optimum fine content which gained maximum strength was about 30%. But for 13% cement content, low fine content and water-cement ratio were more useful than others. In the multi regression analysis, significant equation was gained.

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Relationship among Chemical Properties of Soils with Different Texture Taken from Plastic Film House of Chungbuk Area (충북지역 시설재배지 토성별 토양화학성의 상호관계)

  • Kim, Jai-Joung;Kang, Seong-Soo;Kim, Ki-In;Hong, Soon-Dal
    • Korean Journal of Soil Science and Fertilizer
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    • v.39 no.3
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    • pp.144-150
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    • 2006
  • Chemical characteristics and their interrelationships of 156 soils included by 74 sandy loam and 82 loam soils collected from plastic film house in Chungbuk area were investigated from 1998 to 2001. Seventeen chemical properties including pH, organic matter (OM), electrical conductivity (EC), inorganic nitrogen, available phosphorus, exchangeable cations, CEC, etc., were analyzed by correlation, standardized partial regression coefficient, and principal factor analysis. Standardized partial regression coefficients of chemical properties were estimated to determine the degree of contribution of EC and OM contents in soils. Principal factor analysis was applied to classify the studied chemical properties into different groups having similar chemical properties. The pH of experimental soils ranged from 4.24 to 7.14 and 4.95 to 7.35 for loam and sandy loam soils, respectively. The EC of soils varied from 0.93 to $15.65dS\;m^{-1}$ for loam and $0.91{\sim}22.30dS\;m^{-1}$ for sandy loam soils, respectively with significant differences among them. The EC measured by 1:5 $H_2O$ dilution method and saturation method were significantly related with 8.163 and 8.599 as the slopes of regression equation for loam and sandy loam soils, respectively. These slopes more than 8.0 in this regression equation was higher than the slope of 5.0 that is estimated from dilution coefficient suggesting that EC measured by 1:5 dilution method might be erratic. The standardized partial regression coefficient of different chemical properties for the estimation of EC was in the order of $NO_3{^-}$ > $Cl^-$ > OM > exchangeable Mg for loam soils and $NO_3{^-}$ > exchangeable Mg > $Cl^-$ for sandy loam soils. Contribution order of the chemical properties based on standardized partial regression coefficient differed 1:5 dilution method and saturation method, indicating that different chemical compounds might be present in the extract solutions of these two methods. Consequently the measurement of EC by saturation method was thought be still better for estimation of chemical property because accuracy of EC measurement by 1:5 dilution method can't be improved by any specific coefficient for adjustment of EC. Regardless of differences in soil textures and extraction methods, correlation coefficients between EC and the other chemical properties were routinely in the order of $NO_3{^-}$ > $Cl^-$ > degree of base saturation > exchangeable Mg > exchangeable Ca > $SO{_4}^{2-}$. The principal factor analysis revealed four factor groups of the chemical properties studied. The groups for sandy loam were as follows; ; 1. salt components, 2. soil reaction components, 3. fixed and adsorption components, 4. CEC components. The groupings of loam soils were similar to sandy loam except that exchangeable Na substituted the CEC of sandy loam.

A study on the Measurement of Interface Friction between Soils and Fibers (흙과 섬유의 상호마찰 특성의 측정에 관한 연구)

  • 장병욱;서동욱;박영곤
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 1998.10a
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    • pp.467-472
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    • 1998
  • The interface friction angle between soil and fibers is important to evaluate improvement of the shear strength on fiber mixed soils. Direct shear test and pullout tort conducted by an apparatus made specially for the purpose of this study, was analyzed to know how fiber and soils affect on interface friction angle. By the results, The value of interface friction angle of sandy soils is larger than that of clayey soils. As a diameter of fiber is large, the value of friction coefficient of sandy soil is increase and that of clayey soil is decrease. An interface friction angle of well graded soil is larger value than that of uniform graded soil

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Herbicidal Phytotoxicity in Relation to the Korean Soil Properties (한국(韓國) 경지토양특성(耕地土壤特性)에 관련(關聯)된 제초제(除草劑) 약해(藥害))

  • Ryang, Hwan-Seung;Chun, Jae-Chul
    • Korean Journal of Weed Science
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    • v.2 no.2
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    • pp.122-128
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    • 1982
  • This paper deals with herbicidal phytotoxicity which may occur because of unique properties of the Korean soils. Analysis of the Korean lowland and upland soils reveals that about 50% of the total area belongs to sandy loam and sandy gravel soils and most of both lowland and upland soils consists of kaolinite clay mineral. The chemical properties such as organic matter, pH, and cation exchange capacity show very low values by which there have been several instances of the herbicidal phytotoxicity occurred throughout the country. In addition, the paper emphasizes the need for selection and use of herbicides in the Korean soils.

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