• Title/Summary/Keyword: Soil pore size distribution

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Preparation and Characterization of Porous Sintered Body Made from Coal Bottom Ash and Dredged soil (석탄(石炭) 바닥재와 준설토(浚渫土)를 이용한 다공성(多孔性) 소결체(燒結體)의 제조 및 특성 평가)

  • Kim, Kang-Duk;Kang, Seung-Gu
    • Resources Recycling
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    • v.19 no.1
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    • pp.33-39
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    • 2010
  • The spheric sintered body with $6{\pm}2mm$ diameter was manufactured in a rotary kiln at $1125^{\circ}C$/15 min using green body formed by pelletizing the batch powder composing of coal bottom ash produced from power plant and dredged soil by 70:30, wt%. And the physical properties of sintered body (BD) were analyzed to confirm the possibility for applying to an absorbent to restore a contaminated soil. The sintered body had a giant pore above 100 ${\mu}m$ and a fine pore below 10 ${\mu}m$, and bulk density was 1.4. Also its specific surface area, porosity and void proportion were $12.0m^2/g$, 30.1% and 38.2% respectively. The crushed body (BD-C), produced by crushing a BD specimen into an irregular shape with a aspect ratio of about 2, was similar to BD specimen at bulk density and pore size distribution. But it had superior values of specific surface area, porosity and void proportion compared with BD specimen owing to a decreased apparent volume due to conversion of closed pore existed at interior of BD to open pore during a crushing process. The IEP of sintered body occurred at about pH=5, so the optimum pH condition of reacting aqueous solution could be known before bonding a microbe to the sintered body. Hence, the optimum void proportion and porosity of an absorbent can be obtained by appropriate mixing a BD with BD-C from the base data calculated in this study.

Behavior of cement-based permeation grouting in cohesionless soil considering clogging phenomena (폐색효과를 고려한 사질토의 시멘트 침투 그라우팅 거동 특성)

  • Seo, Jong-Woo;Lee, In-Mo;Kim, Byung-Kyu;Kwon, Young-Sam
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.20 no.2
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    • pp.485-500
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    • 2018
  • The behavior of cement-based permeation grouting is divided into three different groups depending on the grain size distribution of the soils: (1) zone of cement-based permeation grouting not feasible; (2) zone of cement-based permeation grouting feasible; and (3) zone in which an accelerating agent should be added to limit the penetration depth. In the cement-based permeation grouting feasible zone, the concept of a representative pore radius was proposed. The ratios of the representative pore radius to the mean pore radius were obtained by performing laboratory test and comparing with clogging theory; these values were in the range of 1.07 and 1.35 depending on the grain size distribution of the soils. In addition, a functional relationship between the lumped parameter (${\theta}$), the representative pore radius and the w/c ratio were derived by comparing and matching experimental results with predictions from theory. In the zone in which the accelerating agent should be added, the controlling process of gel time to limit the penetration depth was experimentally verified. The test results matched well with those obtained from theory utilizing the developed grout penetration program on condition that the viscosity increasing tendency of grout suspension with time is properly taken into account.

Dynamic Deformation Characteristics of Sands Under Various Drainage Conditions (간극비를 고려한 흙-수분특성 방정식의 적용성 평가)

  • Lim, Seong-Yoon;Song, Chang-Seob
    • Journal of the Korean Geotechnical Society
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    • v.23 no.11
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    • pp.39-48
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    • 2007
  • The soil-water characteristic curve(SWCC) is a useful tool in the prediction of the engineering behavior of unsaturated soils. Several equations are available in the literature to mathematically represent the experimental behavior of the SWCC. Some equations are based on the assumption that the shape of curve is dependent upon pore-size distribution. Other equations assume that SWCC can be estimated from the grain size distribution and the physical properties of soils. This study evaluated the suitability of using two different SWCC equations for defining the relationship between water content and matric suction. Various parameters that influence the SWCC behavior are also briefly discussed.

Evaluation of CPTU Cone Factor of Silty Soil with Low Plasticity Focusing on Undrained Shear Strength Characteristics (저소성 실트지반의 비배수 전단강도 특성을 고려한 CPTU 콘계수 평가)

  • Kim, Ju-Hyun
    • Journal of the Korean Geosynthetics Society
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    • v.16 no.1
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    • pp.73-83
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    • 2017
  • Laboratory and in-situ tests were conducted to evaluate the cone factors for the layers with low plasticity containing a lot of silty and sand soils from the west coast (Incheon, Hwaseong and Gunsan areas) and its applicability was evaluated based on these results. The cone factors were evaluated from 19 to 23 based on unconfined compression strengths (qu), from 13 to 13.8 based on simple CU strengths and from 11.6 to 13.1 based on field vane strengths, respectively. The unconfined compression strengths of undisturbed silty soil samples with low plasticity were considerably underestimated due to the change of in-situ residual effective stress during sampling. Half of unconfined compression strength (qu/2) based cone factors of silty soils with low plasticity fluctuated and were approximately 1.8 times higher than simple CU based values of these soils. When evaluating cone factors of these soils, it should be judged overall on the physical properties such as the grain size distribution and soil plasticity and on the fluctuation of the corrected cone resistance and the sleeve friction due to the distribution of sandseam in the ground including pore pressure parameter.

Time dependent behavior of piled raft foundation in clayey soil

  • Fattah, Mohammed Y.;Al-Mosawi, Mosa J.;Al-Zayadi, Abbas A.O.
    • Geomechanics and Engineering
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    • v.5 no.1
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    • pp.17-36
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    • 2013
  • Settlement of the piled raft can be estimated even after years of completing the construction of any structure over the foundation. This study is devoted to carry out numerical analysis by the finite element method of the consolidation settlement of piled rafts over clayey soils and detecting the dissipation of excess pore water pressure and its effect on bearing capacity of piled raft foundations. The ABAQUS computer program is used as a finite element tool and the soil is represented by the modified Drucker-Prager/cap model. Five different configurations of pile groups are simulated in the finite element analysis. It was found that the settlement beneath the piled raft foundation resulted from the dissipation of excess pore water pressure considerably affects the final settlement of the foundation, and enough attention should be paid to settlement variation with time. The settlement behavior of unpiled raft shows bowl shaped settlement profile with maximum at the center. The degree of curvature of the raft under vertical load increases with the decrease of the raft thickness. For the same vertical load, the differential settlement of raft of ($10{\times}10m$) size decreases by more than 90% when the raft thickness increased from 0.75 m to 1.5 m. The average load carried by piles depends on the number of piles in the group. The groups of ($2{\times}1$, $3{\times}1$, $2{\times}2$, $3{\times}2$, and $3{\times}3$) piles were found to carry about 24%, 32%, 42%, 58%, and 79% of the total vertical load. The distribution of load between piles becomes more uniform with the increase of raft thickness.

Techniques to Estimate Permeability Based on Spectral Induced Polarization Survey (광대역유도분극 탐사에 기초한 유체투과도 예측기법들)

  • Kim, Bitnarae;Cho, AHyun;Weller, Andreas;Nam, Myung Jin
    • Journal of Soil and Groundwater Environment
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    • v.25 no.2_spc
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    • pp.55-69
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    • 2020
  • Permeability-analyzing methods commonly involve small-scale drilling, such as pumping or slug test, but it is difficult to identify overall distribution of permeability of the entire target sites due to high cost and time requirement. Spectral induced polarization (SIP) method is known to be capable of providing distributions of both the porosity and the pore size, the two major parameters determining permeability of the porous medium. The relationship between SIP variables and permeability has been studied to identify the hydrological characteristics of target sites. Kozeny-Carman formula has been improved through many experiments to better predict fluid permeability with electrical properties. In this work, the permeability prediction techniques based on SIP data were presented in accordance with the hydrogeological and electrical characteristics of a porous medium. Following the summary of the techniques, various models and related laboratory experiments were analyzed and examined. In addition, the field applicability of the prediction model was evaluated by field case analysis.

No-Tillage Agriculture of Korean-Style on Recycled Ridge II. Changes in Physical Properties : Water-Stable Aggregate, Bulk density, and Three Phase Ratio to Retain Water at Plastic Film Greenhouse Soil in No-Tillage System (두둑을 재활용한 한국형 무경운 농업 II. 시설 무경운 토양의 물리적 특성 : 입단과 용적밀도 및 삼상변화)

  • Yang, Seung-Koo;Shin, Gil-Ho;Kim, Sun-Kook;Kim, Hee-Kwon;Kim, Hyun-Woo;Jung, Woo-Jin
    • Korean Journal of Organic Agriculture
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    • v.24 no.4
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    • pp.719-733
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    • 2016
  • This study was carried out to investigate the effect of no-tillage on sequential cropping supported from recycling of first crop ridge on the productivity of crop and physical properties of soil under green house condition. This study is a part of "No-tillage agriculture of Korea-type on recycled ridge". From results for distribution of soil particle size with time process after tillage, soil particles were composed with granular structure in both tillage and no-tillage. No-tillage soil in distribution of above 2 mm soil particle increased at top soil and subsoil compared with tillage soil. Tillage and one year of no-tillage soil were not a significant difference at above 0.25 mm~below 0.5 mm, above 0.5 mm~below 1.0 mm, and above 1.0 mm of water-stable aggregate. Two years of no-tillage soil was significantly increased by 8.2%, 4.5%, and 1.7% at above 0.25 mm~below 0.5 mm, above 0.5 mm~below 1.0 mm, and above 1.0 mm of water-stable aggregate, respectively, compared with one year of no-tillage. Bulk density of top soil was $1.10MG\;m^3$ at tillage and $1.30MG\;m^3$ at one year of no-tillage. Bulk density of top soil was $1.14MG\;m^3$ at two years and $1.03MG\;m^3$ at three years of no-tillage, respectively. Bulk density of subsoil was a similar tendency. Solid phase ratio in top soil and subsoil was increased at one year of no-tillage compared with tillage soil, while soil phase ratio decreased at two and three years of no-tillage. Pore space ratio in tillage top soil (58.5%) was decreased by 8.5% at compared with no-tillage soil (51.0%). Pore space ratio was 56.9% and 61.2% at two and three years of no-tillage soil, respectively. Subsoil was a similar tendency. Gaseous phase ratio was decreased at one year of no-tillage soil, and increased at two and three years of no-tillage soil compared with tillage soil. Liquid phase ratio in top soil was increased at one year of no-tillage (28.3%), and decreased at two years (23.4%) and at three years (18.3 %) of no-tillage soil compared with tillage soil (24.2%). Subsoil was a similar tendency. Liquid phase ratio in subsoil was increased than top soil.

Vertical Distribution of Bulk Density and Salts in a Plastic Film House Soil (깊이별 용적밀도가 다른 시설재배지 토양의 염류분포)

  • Kim, Pil-Joo;Lee, Do-Kyoung;Chung, Doug-Young
    • Korean Journal of Soil Science and Fertilizer
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    • v.30 no.3
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    • pp.226-233
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    • 1997
  • To investigate the salt accumulation in the plastic film house soils, bulk density, electrical conductivity(EC), exchangeable canons and water soluble anions were determined at different depths(0~60cm) in the salt-accumulated plastic film house soils in Yesan, Chungnam, Korea. Bulk density were increased from $1.2Mg/m^3$ to $1.5Mg/m^3$ as the depth changed from 0cm(top soil) to 30cm(subsoil) below the soil surface, whereas the bulk densities between 30cm to 60cm slightly decreased to $1.42Mg/m^3$. These changes of soil bulk densities might influence the porosity and pore size distribution, resulting in affecting the water flow throughout, soil layers. Electrical conductivity and Exchangeable sodium percentage(ESP) for 0 to 10cm soil layer were 5.08 dS/m and 6.4, respectively, while the EC was decreased to less than 1.63 dS/m in 20~30cm depth and about 0.7 dS/m. Salt accumulation patterns in the plastic film house soils might be influenced by the changes of the bulk densities in soil.

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Analysis of the Characteristics of Liquidization Behavior of Sand Ground in Korea Using Repeated Triaxial Compression Test (반복삼축압축시험을 이용한 국내 모래지반의 액상화 거동 특성 비교)

  • Seo, Hyeok;Kim, Daehyeon
    • The Journal of Engineering Geology
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    • v.31 no.4
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    • pp.493-506
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    • 2021
  • Liquefaction refers to a phenomenon in which excessive pore water pressure occurs when a dynamic load such as an earthquake rapidly acts on a loose sandy soil saturated with soil, and the ground loses effective stress and becomes liquefied. The indoor repeated test for liquefaction evaluation can be confirmed through the repeated triaxial compression test and the repeated shear test. In this regard, this study tried to confirm the liquefaction resistance strength according to the relative density and particle size distribution of sand using the repeated triaxial compression test. As a result of the experiment, it was confirmed that the liquefaction resistance strength increased as the relative density increased regardless of the soil classification, and the liquefaction resistance strength according to the particle size distribution of the sand was confirmed that the liquefaction resistance strength of the SP sample close to SW was significantly higher. In addition, as a result of analyzing 30% of fine powder compared to 0% of fine powder, as the relative density increased to 40~70%, the liquefaction resistance strength decreased by 5~20%, and the domestic weathered soil ground had a fine liquefaction resistance strength compared to Jumunjin standard sand. When the minute was 10%, it was measured to be 30% or more, and when the fine particle was 30%, it was measured to be less than 50%.

Fabrication of Calcined Clay Granule Comprising Zeolite (제올라이트를 함유하는 소성점토의 제조)

  • Kim, Byoung-Gon;Lee, Gye-Seung;Park, Chong-Lyuck;Jeon, Ho-Seok;Jeong, Soo-Bok
    • Korean Journal of Soil Science and Fertilizer
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    • v.41 no.4
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    • pp.239-246
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    • 2008
  • This research tried to find out the optimum fabrication method of calcined clay granules comprising zeolite. Kaolin clay and natural zeolite powder were used as raw materials of calcined clay, and silica stone powder was used for controlling the porosity of the granules. The granulation was performed with two kinds of granulators: a pan granulator and a high-shear mixer granulator. Various granules were fabricated by the mixing ratios and the rotation speeds of the granulators, and were heated from 400 to $700^{\circ}C$ at $100^{\circ}C$ interval. The crushing strength, pore size distribution, and CEC of the granules were measured. The evaluation method for the resistance of granules to human treading was created and the tests were conducted at dry and wet conditions. The resistance and crushing strength improved in proportion to the rotation speed of the granulator and the heating temperature, but the CEC decreased. The pellet made by the pan granulator did not have the strength against treading upon heating to below $700^{\circ}C$, but the pellet made by the high-shear mixer granulator endured the treading test upon heating to over $500^{\circ}C$