• Title, Summary, Keyword: 지오그리드

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Development of Geogrid made with High Modulus & Low Elongation Fiber Glass (고 모듈러스.저신도 유리섬유를 이용한 지오그리드 개발)

  • 김갑진;김유겸;조항원;이종순;강승문
    • Proceedings of the Korean Fiber Society Conference
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    • pp.95-99
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    • 2001
  • 토목섬유 (Geosynthetics) 중에서 사면, 옹벽 및 도로 보강을 위하여 사용되는 지오그리드는 고강력의 강도 및 적절한 신도가 필요하다. PP 또는 HDPE 의 지오그리드 등도 사용되고 있으나 creep성이 커서 장기적인 보강을 위해서는 사용에 제약을 받기도 하며, 열에 의한 변형이 쉬워 도로 시공시 변형이 발생할 수도 있다. (중략)

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Stress Distribution under a Geogrid-Reinforced Soil Pad (지오그리드로 보강한 성토지반의 응력분포)

  • 이규진;신방웅;신은철
    • Journal of the Korean Geotechnical Society
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    • v.17 no.4
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    • pp.87-91
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    • 2001
  • 얕은 기초의 침하는 기초에 가해지는 상재 하중의 지반에 전달될 때 분포되는 응력의 특성과 크기에 관련되어 일어난다. 일반적으로 지반의 보강재로 사용되는 지오그리드로 두께가 작은 토체를 보강하면 지중에 전달되는 응력을 재분포시켜 감소시킨다. 이 논문에서는 현장시험을 통하여 여러 층의 지오그리드로 토체를 보강시 토체 상부에 가해지는 원형 등분포 하중하에서 토체의 응력 분포를 측정하였다. 인천국제 공항 건설 현장의 준설 매립 구간에서 행하여진 이 시험을 통하여, 지오그리드로 보강된 토체의 하중 분포는 기초에 가해지는 하중 강도와, 보강재 포설층수, 토체의 두께의 함수로 나타낼 수 있다.

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Settlement Reduction Effect of the Geogrid Reinforced Stone Column System (고강도 지오그리드로 보강된 Stone Column 공법의 침하감소효과)

  • Park, Sis-Am;Cho, Sung-Han;Yoo, Chung-Sik;Lee, Dae-Young
    • Journal of the Korean Geosynthetics Society
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    • v.5 no.1
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    • pp.15-23
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    • 2006
  • Sand Compaction Pile and Stone Column method have been used in widely during several decades as a technique to reinforce soft soils and increasing ultimate bearing capacity, accelerate consolidation settlement of the foundation ground. Stone column method, making a compaction pile using crushed stone, is a soft ground improvement method. However, stone column method is difficult to apply to the ground which is not mobilized enough lateral confine pressure because no bulging failure resistance. Hence, in present study, development the geogrid reinforced stone column system for settlement reduction and wide range of application of stone columns. To develop this system, triaxial compression tests were conducted for evaluation which is about behavior characteristics of stone column on replacement rate and confine pressure. Then, 3-dimensional numerical analysis were evaluated for application of the GRSC (geogrid reinforced stone column) system as evaluate behavior characteristics and settlement reduction effect of stone column reinforced by geogrid on types and reinforcing depth change of geogrid.

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Undrained Characteristics of Geogrid-Encased Stone Column under Cyclic Load Using Reduced-Scale Model Tests (축소모형실험에 의한 반복하중 작용시 지오그리드 감쌈 쇄석말뚝의 비배수 거동 특성)

  • Choi, Jin-Wook;Lee, Dae-Young;Yoo, Chung-Sik
    • Journal of the Korean Geotechnical Society
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    • v.29 no.1
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    • pp.109-120
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    • 2013
  • This paper presents the results of a laboratory investigation into a study on undrained characteristics of a geogrid-encased stone column (GESC) installed in soft clay under cyclic load. In order to analyze behavior of settlement, pore water pressure, stress concentration ratio and strain of the GESC compared to a stone column, a series of reduced-scale laboratory tests were performed. The model tests show that GESC provides a simple and effective method of deformation resistance and settlement restraint when a short-term cyclic load is applied. The maximum strain of geogrid occurred at 1.2D and 1.5D from the top of the column. This paper highlights the importance of considering overlay effect and replacement ratio on cyclic load supporting GESC.

Installation Damage Assessment of Geogrids by Laboratory Tester (실내 시험기에 의한 지오그리드의 시공 시 손상 평가)

  • Jeon, Han-Yong;Jin, Yong-Bum;Jang, Yeon-Soo;Yoo, Chung-Sik
    • Journal of the Korean Geotechnical Society
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    • v.23 no.7
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    • pp.77-86
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    • 2007
  • Installation damage of 3 types of geogrids was evaluated with compaction condition by laboratory tester. This experimental was in accordance with ENV ISO 10722-1. First, soil distribution and water content were conducted. And then we changed cyclic loading time and type of geogrids as a factor of installation damage. The samples are woven, warp-knitted, welded type of 6, 8, 10T. This study aims to give an insight into the relationships between installation damage and cyclic loading time. The result of studies was that strength of the damaged geogrids can be closely correlated with the time of loading cycles. Especially, welded type shows slower slope than two types of geogrids due to coating materials. That means welded type is coated with PP (Polypropylene), but the other two types of geogrids are coated with PVC (Polyvinyl Chloride). To confirm another factor different method was performed. The size of soil was used between 9.5 mm and 23.5 m to compare initial experimental. Cyclic loading compaction is taken 200 times before installation test and the reason is that the reduction factor of this case by installation damage was higher than other compaction loading conditions.

Experimental Investigations of Combination Effects of Installation Damage and Creep Deformation on Long-Term Design Strength of Geogrids (지오그리드의 장기설계인장강도에 미치는 시공시 손상 및 크리프 변형 복합효과에 대한 실험적 평가)

  • Cho, Sam-Deok;Lee, Kwang-Wu;Oh, Se-Yong;Lee, Do-Hee
    • Journal of the Korean Geosynthetics Society
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    • v.4 no.4
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    • pp.23-37
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    • 2005
  • The factors affecting the long-term design strength of geogrid can be classified into factors on creep deformation, installation damage, temperature, chemical degradation and biological degradation. Especially, creep deformation and installation damage are considered as main factors to determine the long-term design strength of geogrid. Current practice in the design of a reinforced soil structures is to calculate the long-term design strength of a geosynthetic reinforcement damaged during installation by multiplying the two partial safety factors, $RF_{ID}$ and $RF_{CR}$. This method assumes that there is no evaluation of synergy effect between installation damage and creep deformation of geogrids. This paper describes the results of a series of experimental study, which are carried out to assess the combined effect of the installation damage and the creep deformation for the long-term design strength of geogrid reinforcements. A series of field tests was carried out to assess installation damage of various geogrids with respect to different fill materials, and then creep tests are conducted to evaluate the creep deformation of both undamaged and damaged geogrids. The results indicated that the tensile strength reduction factors, RF, considering the combined effect between the installation damage and the creep deformation is less than that calculated by the current design method.

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Reinforcement and Arching Effect of Geogrid-reinforced and Pile-supported Embankments (지오그리드와 말뚝으로 보강된 성토지반의 보강 및 아칭효과 연구)

  • Oh Young-In;Shin Eun-Chul
    • Journal of the Korean Geotechnical Society
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    • v.21 no.10
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    • pp.5-16
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    • 2005
  • Geosynthetic-reinforced and pile-supported embankments have been increasingly used and researched around the world. The inclusion of one or multiple geosynthetic reinforcements over the pile is intended to enhance the efficiency of load transfer from soft ground to piles, to reduce total and differential settlement and increase global or local stability. In this paper, the reinforcement effectiveness and arching effect of the geogrid-reinforced and pile-supported embankments have been studied in terms of field model tests and numerical analysis with varying the space between piles and reinforcement. 2-dimensional numerical analysis has been conducted using the FLAC (Fast Lagrangian Analysis of Continua) program. And load transfer mechanisms between soil-piles-geogrid were investigated. The mechanisms of load transfer can be considered as a combination of embankment soil arching, tension geogrid, and stress concentration due to the stiffness difference between pile and soft ground. Based on the field model test and numerical analysis results, it was found that the geosynthetic reinforcement slightly interferes with soil arching, and helps reduce differential settlement of the soft ground. Also. at the D/b=3 (D: spacing of pile cap, b: diameter of pile), the total settlement is reduced by about $40\%$ compared to that without reinforcement. For $D/b{\ge}6$, the effectiveness of geogrid reinforcement in reducing settlement is negligible.

Suggestion for Interpretation of Limit Creep Strain of Geogrids (지오그리드의 한계 크리프 변형률 해석을 위한 제안)

  • Jeon, Han-Yong;Mok, Mun-Sung
    • Journal of the Korean Geosynthetics Society
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    • v.6 no.4
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    • pp.1-6
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    • 2007
  • New procedure for evaluation of creep reduction factor by the limit creep strain concept was introduced through the analysis of creep test results. To determine the limit creep strain of the geogrids, the Sherby-Dorm Plots were applied and the results of this procedure were compared and interpreted, respectively. From this, it is seen that the creep reduction factors were 1.45 for the geogrid samples used in this study. Through the comparison of creep reduction factors in 10% creep strain criteria, it was confirmed that the range of creep reduction factor is about 0.06~0.14 for the geogrid samples in this study.

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Behavior of Underground Flexible Pipe According to Ground Characteristics (지반특성에 따른 지중 연성관의 거동특성)

  • Chang, Yongchai;Kim, Yonghyu;Lee, Seungeun;Park, Kichul;No, Jinsuk
    • Journal of the Korean Geoenvironmental Society
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    • v.10 no.4
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    • pp.41-48
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    • 2009
  • A flexible pipe was buried 10cm below the ground formed with standard sand to observe changes in the shape of the pipe according to the behavior of ground at each relative density. Changes in the shape of the pipe in each ground were observed to examine the behavior of the pipe under the state of reinforced ground after installing geogrid under the pipe. Ground reinforced using geogrid formed tensile force on the reinforcement material with increase in the vertical load and showed reduction in settlement under identical vertical load with existence of reinforcement. Distributions of ground deformation of 100% relative density and 70% relative density had clear difference. Reinforced ground with 70% density converged to the ground reaction of final settlement of non-reinforced ground with 100% density at final settlement of 100 mm. Because the shape of lower part strain of the buried pipe is similar to that of un-reinforced ground with relative density of 100%, reinforcement effect by geogrid in soft ground can be anticipated.

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Friction Characteristics of Geogrid -Light Weight Soil Mixed with Small Pieces of Waste EPS (지오그리드-폐 EPS조각 혼합경량토의 마찰특성)

  • 김홍택;방윤경
    • Geotechnical Engineering
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    • v.12 no.6
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    • pp.163-184
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    • 1996
  • In this study, physical and geotechnical properties of the light weight mixed soil( weathered granite soil mixed with small pieces of waste EPS) were analyzed by laboratory experiments to examine its suitability for backfill materials of the reinforced-earth walls. Friction characteristics of geogrid-light weight sized soil were also investigated by performing the pullout tests for two types of geogrids having different flexural rigidity. Also a procedure was proposed to evaluate friction strength between geogrid and light weight miffed soil by using a stress-strain relationship of the orthotropic composite material subjected to both longitudinal and vertical loadings. By the procedure proposed in this study, values of the calibration coefficients ul and uf applicable for the evaluation of friction strengths between two types of geogrids and light weight mixed soils were further presented.

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