• Title/Summary/Keyword: Geosynthetic

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매립지 침출수의 효과적인 제거를 위한 반응성 차수재 개발

  • 이현주;박재우
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2003.09a
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    • pp.395-398
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    • 2003
  • Geosynthetic Clay Liners(GCLs) have been widely used as hydraulic barrier in landfills and remediation projects of contaminated sites. The aim of this research is to modify GCLs for effective removal of contaminants. We perform the free swell test, hydraulic conductivity test, and contaminants (TCE, hexavalent chromium, and nitrate) removal test on the bentonite-ZVI mixture with various ZVI content. As the ZVI content increased, contaminants removal efficiencies and swell volume increased, and hydraulic conductivity decreased.

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Geosynthetic Clay Liner(GCL)의 제조 및 물성 평가

  • 전한용;최윤희;김흥관
    • Proceedings of the Korean Fiber Society Conference
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    • 1998.10a
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    • pp.352-355
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    • 1998
  • 토목섬유제품 중에서 차수재조 널리 사용되는 지오멤브레인은 1$\times$$10^{-12}$의 낮은 투수계수를 갖고 있지만 시공전후 찢어지거나 구멍이 뚫리게 되면 침출수의 유출이 발생하여 환경오염을 일으키게 된다. 이를 보완하기 위해 친수성과 팽윤성이 큰 벤토나이트 물질을 이용한 Geosynthetic Clay Liner(GCL) 복합재료가 개발되었다. GCL은 지오텍스타일이나 지오멤브레인사이에 벤토나이트를 충진시키고, 접착제 또는 니들펀칭(needle-punching)이나 스티칭(stitching)과 같은 기계적인 방법으로 결합한 복합재료이다. (중략)

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Load Carrying Capacity of Geosynthetic Reinforced Railway Subgrade Under Cyclic Load (토목섬유 보강재로 보강된 철도 노반의 반복하중 하중지지력 연구)

  • Hong, SeungRok;Cho, Yungyu;Choi, JungHyuk;Jeong, Yongjun;Yoo, ChungSik
    • Journal of the Korean Geosynthetics Society
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    • v.12 no.4
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    • pp.109-121
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    • 2013
  • This paper studied the characteristics of bearing capacity of railway reinforced with geosynthetic against repetitive loading of train. The railway that was based on the porous pavement substructure ground and reinforced with geosynthetic was copied. In order to analyze load carrying capacity of geosynthetic, we have had 3cases experiments - in the first case, the ground was non reinforced, second case was reinforced geocell and last case was reinforced geogrid - and all of them were reduced-scale laboratory tests. The results of the analyses indicated that the bearing capacity of the reinforced geogrid increases much more than the reinforced geocell. Residual deformation of the initial cyclic load was larger than the secondary cyclic loads.

A Study on the Confining Effect Due to Geosynthetics Wrapping Compacted Soil Specimen (토목섬유로 보강된 다짐토 공시체의 구속효과 관한 연구)

  • Kim, Eun Ra;Iizuka, Atsushi;Kim, You-Seong;Park, Hong
    • Journal of the Korean Geotechnical Society
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    • v.20 no.5
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    • pp.5-16
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    • 2004
  • This paper presents the modeling of geosynthetic-reinforced compacted soils and discusses the reinforcement effect arising from confining the dilatancy deformation of the soil by geosynthetics. A series of compressive shear tests for compacted sandy soil specimens wrapped by geosynthetics are carried out by quantitatively examining the geosynthetic-reinforcement effect, occurring from a confinement of the dilative deformation in compacted soils during shearing. In the test, the initial degree of compaction is changed for each series of sandy soil specimens so that each series has different degree of dilatancy characteristics. Herein, the axial forces working on the geosynthetics so as to prevent dilative deformation of compacted soils during shearing are measured. Furthermore, the elasto-plastic modeling of compacted soils and a rational determination procedure for input parameters needed in the elasto-plastic modeling are presented. And to describe the irreversible deformation characteristics of compacted soils during shearing, the subloading yielding surface (Hashiguchi (1989)) to the elasto-plastic modeling is introduced. Finally, the elasto-plastic finite element simulation is carried out and the geosynthetic-reinforcement effect is discussed.

An Evaluation of Interface Shear Strength between Geosynthetic Clay Liner and Geomembrane (토목섬유 점토 차수재(GCL)와 지오멤브레인(GM)의 접촉 전단강도 평가)

  • 서민우;김동진;박준범;박인준
    • Journal of the Korean Geotechnical Society
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    • v.18 no.4
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    • pp.137-146
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    • 2002
  • Geomembrane, compacted clay liner, and geosynthetic clay liner (GCL) are widely used to prevent leachate from leaking to adjacent geo-environment at a municipal solid waste (MSW) landfill. Interface shear strength between GCL and geomembrane installed at a landfill side slope is important properties for the safe design of side liner or final cover systems. The interface shear strength between two geosynthetics was estimated by a large direct shear test in this study. The shear strength was evaluated by the Mohr-Coulomb failure criterion. The effects of normal stress, hydration or dry condition, and a hydration method were investigated. The test results show that the interface shear strength and shear behavior varied depending up on the level of normal stress, the type of geosynthetic combinations, and a hydration method. When GCLs were sheared after being hydrated under 6kPa loading, the results were consistent with those published by other researchers. Summaries of friction angles, normal stress and hydration condition is presented. These friction angles could be used as a reference value at a site where similar geosynthetics are installed.

The Effect of Displacement Rate on Shear Characteristics of Geotextile-involved Ceosynthetic Interfaces (지오텍스타일이 포함된 토목섬유 경계면의 전단특성에 대한 변위속도 효과)

  • 김진만
    • Journal of the Korean Geotechnical Society
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    • v.19 no.1
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    • pp.173-180
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    • 2003
  • In spite of its potential importance in the assessment of geosynthetic-related dynamic problems, no serious attempt has yet been made to investigate a probable dependence of dynamic friction resistance of the geosynthetic interface on shear displacement rate. Hence, an experimental study of geosynthetics was carried out on a shaking table, and the relationship between dynamic friction resistance and shear displacement rate of geosynthetic interfaces was investigated. A cyclic, displacement rate-controlled experimental setup was used. The subsequent multiple rate tests showed that interfaces that involve geotextiles have such unique shearing characteristics that shear strengths tend to increase with displacement rate. In contrast, once submerged with water, the shear strength appears to be no longer dependent on the displacement rate, partly due to lubrication effect of water trapped inside the interface. The results of the experimental study can be used in the seismic safety assessment of a landfill cover and slope where the geosynthetic materials are exposed to a relatively low normal stress.

A Fundamental Study on Behavior Characteristics of the Geosynthetic Composite Reinforcement in the Weathered Granite Backfill Soils (화강풍화토 뒤채움흙 내부 토목섬유 복합보강재의 거동특성에 관한 기초연구)

  • 김홍택;김승욱;전한용;이인모
    • Journal of the Korean Geotechnical Society
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    • v.15 no.5
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    • pp.171-191
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    • 1999
  • The final aim of this research is to systematize the reinforced-earth wall system using the geosynthetic composite reinforcement in the weathered granite backfill soils having relatively large amount of fines. As a staged endeavour to accomplish this purpose, laboratory pull-out tests and finite element modeling are carried out in the present study focusing on the analyses of friction characteristics associated with interaction behaviors of the geosynthetic composite reinforcement composed of geogrid with a superior function in tensile resistance and geotextile with sufficient drainage effects. In addition, drainage effects of the geotextile below geogrid are examined based on the analysis of finite difference numerical modeling. From the present investigation, it is concluded that the geosynthetic composite reinforcement in the weathered granite backfills may possibly be used to achieve effects on both a reduction of deformations and an increase of the tensile resistance, together with drainage effects resulting from the geotextile.

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The Determination of Required Tensile Strength of Geosynthetic Reinforcements for Embankment on Soft Ground (연약지반 보강성토에서 섬유보강재 소요인장강도의 결정)

  • 이광열;황재홍;구태곤
    • Journal of the Korean Geotechnical Society
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    • v.19 no.6
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    • pp.379-385
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    • 2003
  • In the existing method to design geosynthetic reinforced embankment, the required strength of reinforcements is determined by vertical stress only rather than strain. This strength is not in accord with tensile strength that behaves as reinforcement in earth structures. The reinforcement and adjacent soil on the failure plan behave in one unit at the initial stress phase but they make a gap in strain as stress increases. This issue may cause a big impact as a critical factor on geosynthetic reinforcement design in earth structures. The quantitative analysis on strain behavior was performed with a PET Mat reinforced embankment on soft ground. From this study, several outstanding discussions are found that tensile strength of reinforcement governs the failure of embankment when the soil stress is greater than failure stress. Also the optimum required tensile strength of geosynthetic reinforcement(Tos) should be determined by stress, displacement, displacement gap and safety factor of soil-PET Mat at the location of PET Mat.

Estimation of Dynamic Interface Friction Properties of Geosynthetics (토목섬유의 동적 경계면 마찰특성 평가)

  • 김동진;서민우;박준범;박인준
    • Journal of the Korean Geotechnical Society
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    • v.19 no.4
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    • pp.265-275
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    • 2003
  • In this study, shaking table tests were conducted to estimate dynamic interface properties between geosynthetics such as geomembrane, geotextile and geosynthetic clay liner. Accelerations of both shaking table and upper box, and relative displacements between geosynthetics under dynamic loading were measured. Also, the influence of normal stress, frequency of excitation and dry/wet conditions were investigated through the analyses of test results. from the test results, it was found that there is a limited acceleration below which dynamic farce can be transmitted between geosynthetics without the loss of horizontal acceleration. Dynamic interface friction angle between geosynthetics could be calculated through the limited acceleration. Relative displacements induced along geosynthetic interfaces under dynamic loading were not consistent depending on the type of interface and test conditions. The maximum slip displacements between geosynthetics are normalized and normalized slip equations were developed for each interface. By using the normalized slip equation, maximum slip displacements for the geosynthetic interface could be predicted for the given base acceleration and frequency of excitation.

Numerical Analysis of Confining Effect Due to Geosynthetics Wrapping Compacted Soil Specimen (토목섬유로 보강된 다짐토 공시체의 구속효과에 관한 수치계산)

  • Kim, Eun-Ra;Kang, Ho-Keun
    • Journal of the Korean Geotechnical Society
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    • v.20 no.2
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    • pp.37-46
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    • 2004
  • This paper presents the modeling of geosynthetic-reinforced soils and discusses the reinforcement effect arising from confining the dilatancy deformation of the soil by geosynthetics. A series of compressive shear tests for compacted sandy soil specimens wrapped by geosynthetics are carried out by quantitatively examining the geosynthetic-reinforcement effect, and it occurred from the confinement of the dilative deformation of compacted soils during shearing. In the test, the initial degree of compaction is changed for each series of sandy soil specimens so that each series has different degree of dilatancy characteristics. Herein, the axial forces working to the geosynthetics so as to prevent dilative deformation of compacted soils during shearing are measured. Furthermore, the elasto-plastic modeling of compacted soils and a rational determination procedure of input parameters needed in the elasto-plastic modeling are presented. In this paper, the subloading yielding surface(Hashiguchi(1989)) is introduced to the elasto-plastic modeling which could describe the irreversible deformation characteristics of compacted soils during shearing. Finally, the elasto-plastic finite element simulation is carried out and the geosynthetic-reinforcement effect is discussed.