• Title/Summary/Keyword: Compaction effect

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Experimental Study on Reinforcement Effect of Geosynthetics for Surplus Soil, an Unsuitable Fill Material (성토재료로 부적합한 현장 발생토의 토목섬유 보강효과에 관한 실험적 연구)

  • Hong, Young-Suk;Im, Jong-Chul;Kang, Sang-Kyun;Yoo, Jae-Won;Kim, Chang-Young
    • Journal of the Korean Geosynthetics Society
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    • v.17 no.1
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    • pp.11-20
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    • 2018
  • Surplus soil is commonly used at construction sites, because suitable fill material is not always immediately available and leads to additional costs. However, most surplus soils do not meet the requirement of suitable fill material to achieve the stability and strength of embankments. In this study, Proctor compaction tests and field compaction tests were performed by installing geosynthetics to resolve the problems caused by compacting unsuitable soils. Compaction energy and the number of geosynthetics were changed under the type A- and D- and type A Proctor compaction tests (KS F 2312), respectively. The field compaction testing using geosynthetics was performed on surplus soils of high water content. Optimum water content and maximum dry density of compacted soil decreased and increased by reinforcing geosynthetics, respectively. Compaction curves behaved with geosynthetics as the compaction curves behaved with higher compaction energy. Efficient compaction was possible because the compaction energy increased to 2.10 and 2.71 times the compaction energy required to achieve the same maximum dry density with one and two geosynthetic layer(s), respectively. Furthermore, field compaction tests verified that efficient compaction was possible because the dry density of unsuitable surplus soils of high water content was increased by reinforcing geosynthetics.

Optimum Compaction Test of Roller Compacted Concrete Pavement (롤러전압 콘크리트포장의 적정 다짐실험 방안 고찰)

  • Chung, Gun Woo;Lee, Seung Woo
    • International Journal of Highway Engineering
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    • v.17 no.3
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    • pp.27-33
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    • 2015
  • PURPOSES : To ensure appropriate RCC properties with sufficient strength development and workability, it is necessary to secure a proper level of consistency. It is also necessary to secure maximum dry density, which is an important factor for increasing the interaction of aggregate interlocking, leading to an augmentation of RCC strength. On the other hand, the dry density of RCC can be changed owing to the compaction conditions, water content, and particle size distribution. A Proctor test and a modified Proctor test were used for determining the optimum water content needed to achieve maximum dry density with different amounts of compaction energy. A Vebe test, on the other hand, was used for checking the level of consistency, which is important for producing a workable mixture. METHODS : To confirm the degree of compaction at various particle sizes, RCC mixtures with different sand/aggregate ratios were evaluated. The Proctor test and modified Proctor test were applied to these mixtures to check the effect of the aggregate gradation and compaction energy on the maximum dry density and optimum water content. During each test, three specimens were produced for all types of water content under each aggregate gradation. A compaction curve and the optimum water content and maximum dry density for each aggregate gradation were then obtained for both tests. The range of water content for the appropriate consistency of each aggregate gradation was determined through a Vebe test. The optimum water content was then evaluated based on this range. RESULTS : The compaction test results show that the modified Proctor test provides a higher maximum dry density and lower optimum water content compared with the standard Proctor test. For the modified Proctor test, two cases of aggregate gradation (s/a = 30% and 70%) had the optimum water contents outside of the appropriate water content range. For the standard Proctor test, on the other hand, none of aggregate gradations provided the optimum water content within the desired range. CONCLUSIONS : The modified Proctor test should be used for an RCC mixture design because it can provide adequacy between maximum dry density and consistency. Moreover, the compaction roller has become highly developed for higher compaction energy.

Analysis of Bearing Capacity Characteristics on Granular Compaction Pile - focusing on the Model Test Results (조립토 다짐말뚝의 지지력 특성 분석 - 모형토조실험 결과를 중심으로)

  • Kang, Yun;Kim, Hong-Taek
    • Journal of the Korean GEO-environmental Society
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    • v.5 no.2
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    • pp.51-62
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    • 2004
  • Granular compaction piles have the load bearing capacity of the soft ground increase and have the settlement of foundation built on the reinforced soil reduce. The granular compaction group piles also have the consolidation of the soft ground accelerate and have the liquefaction caused by earthquake prevent using the granular materials such as sand, gravel, stone etc. However, this method is one of unuseful methods in Korea. The Granular compaction piles are constructed by grouping it with a raft system. The confining pressure at the center of bulging failure depth is a major variable in relation to estimate for the ultimate bearing capacity of the granular compaction piles. Therefore, a share of loading is determined considering the effect of load concentration ratio between the granular compaction piles and surrounding soils, and varies the magnitude of the confining pressure. In this study, method for the determination of the ultimate bearing capacity is proposed to apply a change of the horizontal pressure considering bulging failure depth, surcharge and loaded area. Also, the ultimate bearing capacity of the granular compaction piles is evaluated on the basis of previous study on the estimation of the ultimate bearing capacity and compared with the results obtained from laboratory scale model tests. And using the result from laboratory model tests, it is studied increase effect of the bearing capacity on the granular compaction piles and variance of coefficient of consolidation for the ground.

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An Experimental Study on the Effects of Bottom Ash Compaction Pile in the Sea Clay Layer (해성 점토지반의 저회다짐말뚝 보강 효과에 관한 실험적 연구)

  • Park, Se-Hyun;Han, Yun-Su;Do, Jong-Nam;Chun, Byung-Sik
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.03a
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    • pp.595-598
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    • 2010
  • Many economical and efficient methods such as sand drain method(SD), plastic board drain(PBD), sand compaction pile, vacuum consolidation method, etc., have been used for soft grounds. The case of sand compaction pile has an effect on accelerating consolidation and increasing bearing capacity by penetration at regular intervals under soft grounds for reducing the drainage path. But, this method has caused not only the nature damage by extracting the sands indiscreetly but also the economical problem for importing the sands because it needs so much sand to make the sand compaction pile. Thus, this study choosed the bottom ash which has similar engineering characteristics with sand. It was performed that clogging test and large direct shear test changing the bottom ash replacement ratio in soft ground for studying strength characteristics of soft ground using bottom ash compaction pile. As a result of the test, the internal friction angle was largely increased and the cohesion was decreased as the replacement ratio increased.

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Sintering Characterization of Alumina Powders by Hot Pressing after Cold Cyclic Compaction -Densification, Grain-Growth and Fracture Toughness- (상온 반복압축 후 가압소결에 의한 알루미나 분말의 소결특성 -치밀화와 결정립 성장 및 파괴인성-)

  • Son, G.S.;Suh, J.;Baik, S.K.;Kim, K.T.
    • Journal of the Korean Ceramic Society
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    • v.30 no.1
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    • pp.62-68
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    • 1993
  • Densification of alumina powder, grain size and fracture toughness of sintered body by hot pressing after cold compaction were investigated and compared to traditional hot pressing process (without cold cyclic compaction). To achieve a higher densification and to reduce the hot pressing time, hot pressing after cold cyclic compaction was more efficient compared to traditional hot pressing. This phenomenon resulted from the increment of packing densityby the acceleration fo rearrangement of powders under cold cyclic compaction. The grain size of sintered body was only dependent on relative density, and densification during hot pressing was governed by thelattice diffusion. Comprisons of grain size, densification mechanism and fracture toughness resulted from hot pressing after/without cold cyclic compaction showed that a low cyclic pressure may not effect on the fragmentation of alumina powders.

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Development of a CAE Tool for P/M Compaction Process and Its Application (금형압축성형공정 해석용 CAE 프로그램 개발 및 적용)

  • Chung Suk-Hwan;Kwon Young-Sam
    • Journal of Powder Materials
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    • v.11 no.5
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    • pp.399-411
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    • 2004
  • Crack generation during die compaction and distortion during sintering have been critical problems for the conventional pressing and sintering process. Until now, trial and error approach with engineers' industrial experiences has been only solution to protect the crack generation and distortion. However, with complexity in shape and process it is very difficult to design process conditions without CAE analysis. We developed the exclusive CAE software (PMsolver/Compaction) for die compaction process. The accuracy of PMsolver is verified by comparing the finite element simulation results with experimental results. The simplified procedures to find material properties are proposed and verified with iron based powder and tungsten carbide powder. Based on the accurate simulation result by PMsolver, the optimal process conditions are designed to get uniform density distribution in a powder compact after die compaction process by using a derivative based optimization scheme. In addition, the effect of non-uniform density distribution in a powder compact on distortion during sintering is shown in case of the fabrication of tungsten carbide insert.

A Study on the Effect of Some Physical Properties of Soil on the Compaction (흙의 물리적 성질이 다짐에 미치는 영향)

  • 김성교;김문기
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.18 no.3
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    • pp.4171-4183
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    • 1976
  • This study is to investigate the effect of some physical properties of soil on the compaction. The compaction effect depends upon various factors such as soil type, moisture content, gradation and compaction energy. In this study, with steady compaction energy, the relationships between maximum dry density and moisture content, gradation and consistency were analyzed by soil types. Some results obtained in this study are summarized as follows 1. Generally, the coarser the grain size, the bigger is the maximum dry density and the smaller is the optimum moisture content and its moisture-dry denisty curve is relatively steep. The finner the grain size, the smaller is the max. dry density and the bigger is the opt. moisture content and its moisture-dry density curve is less steep. 2. The relationship between max. dry density (${\gamma}$dmax) and opt. moisture content, void ratio, clay content, percent passing of No. 200 sieve, liquid limit and plastic limit can be represented by the equation ${\gamma}$dmax =ao+a1X(a0>0, a1<0) 3. The relationship between opt. moisture content (Wopt) and clay content, percent passing of No. 200 sieve, liquid limit and plastic limit can be represented by the equation Wopt=a0+a1X(a0>0, al>0). 4. The fact that maximum dry density of the compacted soil is decreased with the increase of the optimum moisture content in any types of soil tested, and the fact that optimum moisture content can be positively correlated with clay content, percent passing of No. 200 sieve, liquid limit and plastic limit of the soil, lead to the conclusion that clay content, percent passing of No. 200 sieve, liquid limit and plastic limit of the soil are direct factors in reduction of the maximum dry density of engineering soil.

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Effect of Particle Breakage on Compaction and Thermal Resistivity of Concrete-based Recycled Aggregates (콘크리트 재생 순환골재의 파쇄 효과에 따른 다짐 및 열저항 특성 연구)

  • Kang, Sungchul;Kim, Gyeonghun;Wi, Jihae;Ahn, Taebong;Lee, Dae-Soo;Choi, Hangseok
    • Journal of the Korean Geotechnical Society
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    • v.31 no.10
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    • pp.17-28
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    • 2015
  • The strict regulations on eco-friendly construction and the significant reduction of natural aggregate resources have raised public concerns on the utilization of recycled aggregates for backfilling a power transmission pipeline trench. In this paper, the particle breakage of concrete-based recycled aggregates and river sand has been experimentally studied during the standard compaction test. The applied compaction energy does not significantly break the river sand particles down, and thus causes no change in the compaction curve, thermal resistivity, and particle gradation characteristics. On the other hand, considerable particle breakage was observed in case of the three recycled aggregates. Such particle breakage leads to enhancing compaction effort, reducing thermal resistivity, and changing particle gradation curve with finer particles that are broken during the first compaction. In addition, particle breakage is more dramatic in lower water contents because pore water may damp down the compaction energy.

Theoretical Development of Compaction Density (다짐밀도의 이론적 전개)

  • Huh, Jung-Do;Kim, Han-Yong;Nam, Young-Kug
    • International Journal of Highway Engineering
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    • v.2 no.1
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    • pp.147-156
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    • 2000
  • Compaction is known to critically affect pavement performance. Due to its importance, a theoretical modelling of compacted density in the term of number of roller coverages is attempted by assuming compaction process essentially identical to pavement rutting. Excellent data fittings by the developed equation may prove the validation of assumptions made as well as justification of its use. According to the derived equation, a plot of density difference with respect to number of roller coverages in the logarithmic scale Produces a linear relationship. However, this linearity is turned out to be deviated by cooling effect, change of amplitude and frequency. Investigation of these three factors proposes a new generalized compaction density equation, which shows a promising future. By applying this general formula, the equations for the number of roller coverages required and the final compaction density obtained for a particular compaction project is derived first time in compaction research.

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A Study on the Design Method of the Reinforced Earth Structures Considering Compaction Induced Stresses (다짐 유발응력을 고려한 보강토 설계방법에 관한 연구)

  • 임철웅;백영식
    • Geotechnical Engineering
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    • v.8 no.4
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    • pp.5-16
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    • 1992
  • The main purpose of this the sutdy is to develop the reinforced earth structure design method considering induced stresses and deflections resulting from placement and compaction of soil. In this paper, the new reinforcement Geolog developed by the author is also introduced which is being used as one of the effective earth reinforcing structure against compaction induced stresses. This study adopted the Seed's bilinear model in the estimation of the com paction induced stresses and compute the peak lateral stresses during compaction by doubled Boussinessq's elastic solution of mirror image theory, thereafter, calculate the residual compaction induced lateral stresses from the above peak lateral stress by the residual fraction. It is considered to be reasonable that the compaction induced stresses be added to the lateral earth pressures estimated from conventional gravity analysis considering the actual stresses during service life of the structures. "GEOLOG", a composite of steel bar and attached concrete stopper is found to be effective against tension and pull - out failure. In this paper, the design method considering the compaction induced stresses and the effect of Geolog reinforcement is suggested for the remforced earth structures where backkfill settlement on displacements are not allowed as in the cases of the bridge abutments or double faced reinforcement earth structures.tructures.

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