• Title/Summary/Keyword: Clay

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Acceleration Variation of Surrounding Ground according to distance from Strip-Type Crushed Stone Foundation (쇄석 띠기초와의 거리에 따른 주변지반의 가속도 변화)

  • Son, Su-Won;Son, Tae-Ik;Kim, Soo-Bong;Kim, Jin-Man
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.1
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    • pp.217-223
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    • 2019
  • In this study, the acceleration changes of the surrounding ground when crushed stones were installed in a strip-type were analyzed using the 1-G shaking table test. The ground was constructed from clay, and the foundation was installed using crushed stone of strip-type form. The response acceleration and response spectrum for various input seismic motions were analyzed. The change in acceleration was examined according to the adjacent distance to the strip-type crushed stone foundation. In the Hachinohe seismic motion results, there was no significant decrease in acceleration, but the maximum response acceleration for the two seismic motions was inversely proportional to the distance from the crushed stone foundation. As a result of the response spectrum analysis, the attenuation period in the long period and the short period input wave were different from each other, and the change in response spectrum affected the maximum acceleration value. As the distance from the crushed stone foundation was increased, the attenuation was larger in the period between 0.08 and 0.5 sec in the Hachinohe seismic motion, the attenuation was larger in the period of less than 0.2 seconds in the Northridge seismic motion.

Estimation of Consolidation Characteristics of Soft Ground in Major River Mouth (주요 강하구 연약지반의 압밀 특성 평가)

  • Lee, JunDae;Kwon, YoungChul;Bae, WooSeok
    • Journal of the Korean GEO-environmental Society
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    • v.20 no.2
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    • pp.69-79
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    • 2019
  • The coastal area forms various sedimentary layers according to the environmental conditions such as the topography and geological features of the upper region of the river, ocean currents, and river mouth. Therefore, identifying the characteristics of the marine clay deposited in the coastal area plays a key role in the investigation of the formation of soft ground. In general, alluvial grounds are formed by a variety of factors such as changes in topography and natural environment, they have very diverse qualities depending on the deposited region or sedimentation conditions. The most important thing for the construction of social infrastructures in soft ground areas is economical and efficient treatment of soft ground. In this study, the author collected data from diverse laboratory and field tests on five areas in western and southern offshore with relatively high reliability, and then statistically analyzed them, thereby presenting standard constants for construction design. Correlation between design parameters such as over consolidation ratio, preconsolidation pressure was analyzed using linear and non-linear regression analyses. Also, proposed distribution characteristics of design parameters in consideration of each region's uncertainty through statistical analyses such as normality verification, outlier removal.

Evaluation of Fluoride Distribution, Fate and Transport Characteristics in Soils (토양 중 불소 분포 및 거동 특성 평가)

  • Lim, Ga-Hee;Lee, Hong-Gil;Kim, Hyoung-Seop;Noh, Hoe-Jung;Ko, Hyoung-Wook;Kim, Ji-In;Jo, Hun-Je;Kim, Hyun-Koo
    • Journal of Soil and Groundwater Environment
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    • v.23 no.6
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    • pp.90-103
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    • 2018
  • Although fluoride is an essential trace element, ingestion of excessive amount of fluoride could have detrimental effect on human health. Generally, the bioavailability of fluoride in soils was low, but it could be harmful to the environment depending on the soil properties. Therefore, it is necessary to understand the concentration distribution, and fate and transport characteristics of fluoride to establish a resonable management strategy for fluoride pollution. This study was conducted to evaluate nationwide fluoride distribution in soils in Korea, as well as its fate and transport characteristics. The average background concentration was 204.5 (15.3~504.8) mg/kg, which is lower than the values of foreign soils. For the three regions of different land use, the average concentration was 229.6 mg/kg in region 1, 195.7 mg/kg in region 2, and 273.4 mg/kg in region 3. The concentration of fluoride was the highest in soils from Youngnam block within tectonic structure derived from metamorphic rocks. The results of sequential extraction to access F bioavailability showed fluoride in soils mainly existed as a residual form, which suggests the bioavailability of fluoride was relatively low. Soil properties such as soil pH, CEC, and clay content were found to affect F bioavailability of soil.

A Study on the Long-term Settlement Characteristics of Thick Clay Deposits Using Field Monitoring (대심도 연약지반의 현장계측을 이용한 장기침하거동특성 분석에 관한 연구)

  • Kwon, Hyun-Wook;Im, Jong-Chul;Chang, Ji-Gun;Kang, Sang-Kyun
    • Journal of the Korean Geosynthetics Society
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    • v.17 no.4
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    • pp.21-28
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    • 2018
  • Despite a number of studies on consolidation behavior that have been carried out in the Nakdong River estuary in Busan, these are focused on the prediction of final settlement during ground improvement process, and there is almost no research on the long-term settlement occurring after that. For the practical study on the long-term settlement, the field monitored settlement data that measured over 10 years in the Busan new port facilities area were used, and the final settlement and predicted time-settlement line were constituted by hyperbolic function. As a result, the measured settlements depend on the thickness of clayey soils, and the pattern were similar to each other and good agreement with the predicted time-settlement line using hyperbolic method. Also, the settlement in the lower non-improved layer occupied 62-76% of total settlement. Information about above results would be quite helpful to understand the long-term settlement behaviors as well as the non-improved layer's settlement is more careful consideration needed at design phase.

Numerical Analysis and Exploring of Ground Condition during Groundwater Drawdown Environment in Open-cut Type Excavation (개착식 굴착공사시 지하수위 저하로 인한 지반상태 탐사 및 해석기법 연구)

  • Han, Yushik
    • Journal of the Korean Geotechnical Society
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    • v.34 no.11
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    • pp.93-105
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    • 2018
  • Precise investigation and interpretation of the ground subsidence risk factors needed to predict and evaluate the settlement problems of the surrounding ground due to the ground excavation. There are various geophysical exploration methods to investigate the ground subsidence risk factors. However, there are factors that influence the characteristics of the underground medium in these geophysical methods, and the actual soil contains complex factors affecting geophysical exploration. Therefore, it is necessary to analyze the effects on the geophysical methods based on the understanding of the geotechnical properties of soil. In this study, a test bed was constructed to consider various complicated factors in the complex ground and the ground behavior was analyzed by numerical analysis. In addition, we analyzed the limitations on investigating the ground subsidence risk factors through ground penetration radar (GPR) survey. As a result, ground subsidence of Open-cut Type Excavation is caused by various factors. Especially, in the case of soft ground condition, it was found that it was greatly influenced by the flow change of groundwater level. At the center frequency of GPR of 250 MHz, the attenuation of the electromagnetic wave is severely attenuated in the clay with high electrical conductivity, making it difficult to penetrate deeply into the ground (4 m below the surface). As the electromagnetic waves pass through the groundwater level below the groundwater, the attenuation of the electromagnetic waves becomes severe.

Strength and Compaction Characteristics of Binder-Stabilized Subgrade Material in Ulsan Area - Main Binder Components : CaO and SO3 - (고화제로 안정처리 된 울산지역 노상재료의 강도 및 다짐특성 - 주 성분이 CaO와 SO3인 고화제 -)

  • Han, Sang-Hyun;Yea, Geu-Guwen;Kim, Hong-Yeon
    • Journal of the Korean Geotechnical Society
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    • v.34 no.12
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    • pp.105-113
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    • 2018
  • In this study, the engineering properties including bearing capacity of subgrades stabilized with a binder are analyzed by laboratory and field experiments. The main components of the binder are CaO and $SO_3$. After the binder was mixed with a low plasticity clay, the passing rates were relatively decreased as the sieve mesh size increased. Not only did the soil type change to silty sand, but engineering properties, such as the plasticity index and modified California bearing ratio (CBR), were improved for the subgrade. A comparison of the compaction curves of the stabilized subgrade and field soil compacted with the same energy demonstrated an increase of approximately 6% in the maximum dry unit weight, slight decrease in optimum moisture content, and considerable increase improvement in grain size. In the modified CBR test, the effect of unit weight and strength increase of the modified soil (with a specific amount of binder) was remarkably improved. As the proportion of granulated material increased after the addition of binder, the swelling was reduced by 3.3 times or more during initial compaction and 6.5 times by final compaction. The unconfined compressive strength of the specimens was maintained at the homogeneous value with a constant design strength. The stabilized subgrade was validated by applying it in the field under the same conditions; this test demonstrated that the bearing capacity coefficients at all six sites after one day of compaction exceeded the target value and exhibited good variability.

Effect of limestone addition on mechanical properties of ceramic tiles with fly ash (플라이애시가 첨가된 도자타일 성능에 석회석 함량이 미치는 효과)

  • Lee, Jin-Wook;Han, Kyu-Sung;Hwang, Kwang-Taek;Kim, Jin-Ho
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.28 no.6
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    • pp.256-262
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    • 2018
  • A great amount of fly ash, which is a waste from a thermal power plant, has not been appropriately recycled until now. Landfill of flay ash causes environmental pollution and enormous economic costs. In this study, manufacturing of architectural ceramic tile was investigated replacing fly ash with clay raw material. The properties of porcelain tile was analyzed after manufacturing porcelain tile with mineral based glaze and fast firing process. In particular, the effect of the fly ash addition on the properties of ceramic tile was investigated by increasing the amount of limestone addition. Porcelain tile with fly ash showed excellent bending strength, water absorption, warping and abrasion resistance. However, a significant decrease in durability was observed through the autoclave test. Addition of limestone increased the water absorption, twisting and hydration expansion of the ceramic tile, but it was confirmed that the durability of the ceramic tile with fly ash was greatly improved. In conclusion, recycled architectural ceramic tiles, which can meet domestic construction standards, could be manufactured with the addition of fly ash and limestone.

Plant Parasitic Nematode Fauna of Heterodera glycines and H. sojae, and Soil Characteristics of Soybean Fields in Gangwon-do and Chungcheongbuk-do (강원과 충북지역 콩씨스트선충과 반짝이콩씨스트선충의 분포상 및 토양 특성)

  • Kim, Youngjoon;Lee, Dong Woon
    • Korean journal of applied entomology
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    • v.58 no.1
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    • pp.37-47
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    • 2019
  • A survey on the geographical distribution of two soybean cyst nematodes, Heterodera glycines and Heterodera sojae, was conducted in soybean cultivation areas in the Gangwon-do and Chungcheongbuk-do provinces. In 67 fields of 10 counties or cities in Gangwon-do province, H. glycines was detected in 13 fields, H. sojae was detected in five fields, and both species were found in two fields. In 84 fields of nine counties or cities in Chungcheongbuk-do province, H. glycines was detected in 27 fields, H. sojae was detected in four fields, and both species were found in five fields. The diversity and dominance of the plant parasitic nematodes in the Gangwon and Chungbuk provinces were not significantly different among the soybean cultivars. The diversity and dominance index of the plant parasitic nematodes according to the presence or absence of soybean cyst nematodes did not show any significant difference between the soybean cultivation areas of both provinces. The relationship between the soybean cyst nematodes and soil chemical properties showed a low coefficient of determination, and the density of soybean cyst nematodes tended to increase as the pH and available phosphate content in soil samples increased. The soil texture of cyst nematode-detected fields was mostly sandy soils, which amounted to about 60% of the total. As the clay and silt content increased, the density of soybean cyst nematodes tended to decrease, and as the sand content increased, the density of cyst nematodes tended to increase.

Material Properties of Soil and Potteries Excavated From Ra-No.19 Site of Pung-nap Mudcastle (풍납토성 라-19호 출토 토양과 토기의 재료학적 특성)

  • Heo, Jun Su;Kim, Jo Yoon;Han, Ji Sun;Kim, Su Kyoung;Lee, Han Hyoung;Moon, Eun Jung;Yoo, Young Mi;Han, Min Su;Seo, Min Seok
    • Korean Journal of Heritage :History & Science
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    • v.45 no.3
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    • pp.194-211
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    • 2012
  • Pung-nap mudcastle has brought wide attention to archaeologists since scientific studies were carried out on the various types of building sites and excavated potteries related to A period of Baekje Kindom when it sat Hansung as the capital. It is identified that clay from Ra-No.19 site of Pung-Nap mudcastle has different from compositions that of residential soil. From archaeological point of view, it is believed that the the soil was a source material for potteries due to the appropriate viscosity and inclusions. Mineralogical and geochemical studies show that the compositions between the source material and randomly chosen two potteries from the same site are similar. Behavior pattern classification of major, trace and rare elements provides also very similar result. Artificial specimen has been made at different temperature in order to estimate firing temperature of the potteries by means of various kinds of instrumental application. As a result of the study, it is believed that the firing temperature of the red and brown pottery was $550{\sim}600^{\circ}C$ and $900{\sim}1,000^{\circ}C$ respectively.

A Study on Stability according to the Conservation Environment for Fixative of Korean Mural Painting Layers (한국 흙벽화 채색층 고착제의 보존환경에 따른 안정성 연구)

  • Jin, Byung-hyuk;Wi, Koang-chul
    • Korean Journal of Heritage :History & Science
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    • v.46 no.3
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    • pp.150-171
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    • 2013
  • The most important part of conservation treatment of murals is to preserve them against the risk of a damage by injecting fixative into them when the painting loses its cohesion or powderization of pigments occurred due to occurrence of cracks inside the painting layer. However, studies on the stability of fixative used for painting layers of murals are still insufficient. This study manufactured a mural as a specimen and colored it with four kinds of pigments including oyster shell white, cinnabar, malachite and red clay and applied four kinds of fixative, including, Paraloid $B-72^{(R)}$, Caparol-$binder^{(R)}$, glue and Hydoxypropyl $cellulose^{(R)}$. artificially generated environmental changes in temperature, humidity and ultraviolet rays which may occur after the completion of conservation treatment. Then the changes in physical properties were observed in multifaceted ways such as color stability, contact angle, brilliance, adhesive strength and surface. As a result, this study found that ultraviolet rays and hot?humid environment have a large impact on color stability causing changes in brightness and chroma of all painting layers where the fixative were applied, except for oyster shell white and are considered the main factors of decomposition by accelerating the aging process of fixatives applied. In comparison to the synthetic resins that were also tested in this study, the traditional glue showed satisfactory results in terms of color stability and influence preservation and the hydrophile property. As it showed exceptionally outstanding adhesive strength in all painting layers in the aspect of adhesive strength, it is considered to be highly stabile for the fixation treatment of painting layers of mural.