• Title, Summary, Keyword: 지오그리드

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

  • Jin, Yong-Bum;Byun, Sung-Won;Jeon, Han-Yong
    • Journal of the Korean Geosynthetics Society
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    • v.5 no.4
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    • pp.43-47
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    • 2006
  • Installation damage of 3 types of geogrids were evaluated with compaction condition. This experimental test was in accordance with ENV ISO 10722-1. Tensile strength of geogrids were decreased with number of cyclic compaction loading without regard to kind of filled material and it was seen that strength decrease tendency showed the dependence on geogrid type. Woven and warp-knitted type geogrids showed the bigger decrease of tensile strength than welded type geogrids.

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Assessments of Installation Damage and Creep Deformation of Geogrids (지오그리드의 시공시 손상 및 크리프 변형 특성 평가)

  • Cho, Sam-Deok;Lee, Kwang-Wu;Oh, Se-Yong;Lee, Do-Hee
    • Journal of the Korean Geosynthetics Society
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    • v.3 no.4
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    • pp.29-40
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    • 2004
  • The factors affecting the long-term design strength of geogrids can be classified into factors on creep deformation, installation damage, temperature, chemical degradation, biological degradation. Especially, creep deformation and installation damage are considered as main factors to determine the long-term design strength of geogrids. This paper describes the results of a series of experimental investigation, which were conducted to assess the installation damage according to different fill materials and creep characteristic of various geogrids. The results of this study show that the installation damage and creep deformation of geogrids significantly depends on a row material and a manufacturing process of geogrids.

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Evaluation of the Relationship between Geogrid Rib Size and Particle Size Distribution of Ballast Materials using Discrete Element Method (개별요소해석법을 이용한 지오그리드 격자 크기와 도상자갈재료 입도분포 상관관계 평가)

  • Pi, Ji-Hyun;Oh, Jeongho
    • Journal of The Korean Society of Civil Engineers
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    • v.36 no.1
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    • pp.143-149
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    • 2016
  • This study evaluated the shear behavior of geogrid reinforced ballast material using a large scale direct shear test and discrete element method (DEM) based on PFC 3D program. The direct shear test was conducted on ballast materials that have different particle size distributions. Whereas the test results revealed that the shear strength generally increased with the larger particle size of ballast material without geogrid reinforcement, the shear behavior of ballast material was found to change pertaining to the relationship between particle size distribution and geogrid rib size. Generally, it is deemed the effectiveness of reinforcement can be achieved when the rib size is two times greater than average particle size. A numerical analysis based on DEM was conducted to verify the test results. The geogrid modeling was successfully completed by calibration process along with sensitivity analysis to have actual tensile strength provided by manufacturer. With a given geogrid model, the parametric evaluation was further carried out to examine the interactive behavior between geogrid and ballast material. Consequently, it was found that the effectiveness zone of geogrid reinforcement generated within a specific depth.

Characteristics of Compressive Strength of Geogrid Mixing Reinforced Lightweight Soil (지오그리드 혼합 보강경량토의 압축강도특성 연구)

  • Kim, Yun-Tae;Kwon, Yong-Kyu;Kim, Hong-Joo
    • Journal of the Korean Geotechnical Society
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    • v.22 no.7
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    • pp.37-44
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    • 2006
  • This paper investigates strength characteristics and stress-strain behaviors of geogrid mixing reinforced lightweight soil. The lightweight soil was reinforced with geogrid in order to increase its compressive strength. Test specimens were fabricated by various mixing conditions including cement content, initial water content, air content and geogrid layer and then unconfined compression tests were carried out. From the experimental results, it was found that unconfined compressive strength as well as stress-strain behavior of lightweight soil was strongly influenced by mixing conditions. The more cement content that is added to the mixture, the greater its unconfined compressive strength. However, the more initial water content or the more air foam content, the less its unconfined compressive strength. It was observed that the compressive strength of reinforced lightweight soil increased reinforcing effect by the geogrid for most cases. Stress-strain relation of geogrid mixing reinforced lightweight soil showed a ductile behavior rather than a brittle behavior. In reinforced lightweight soil, secant modulus ($E_{50}$) also increased as its compressive strength increased due to the inclusion of geogrid.

Short- and Long-term Load Carrying Capacity of Geogrid-encased Stone Column - A numerical investigation (지오그리드 감쌈 쇄석기둥 공법의 장.단기 하중 지지 특성 - 유한요소해석을 통한 고찰)

  • Lee, Dae-Young;Song, Ah-Ran;Kim, Sun-Bin;Yoo, Chung-Sik
    • Journal of the Korean Geotechnical Society
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    • v.23 no.8
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    • pp.5-16
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    • 2007
  • The stone column method is widely used in Europe as an alternative to conventional pile foundations. Several benefits of using the stone column method include sound performance, low cost, expediency of construction, and liquefaction resistance among others. Recently, geosynthetic-encased stone column approach has been developed to improve its load carrying capacity through increasing confinement effect. Although such a concept has been successfully applied in practice, fundamentals of the method have not been fully explored. This paper presents the results of an investigation on the load carrying capacity of geogrid-encased stone column using a series of 2D finite element analyses. A parametric study was then conducted for influencing factors such as effect of geogrid encasement, encasement length, geogrid strength, among others. The results of the analyses indicated improved short- and long-term load carrying capacity of the geogrid-encased stone column method has advantages over the conventional stone column method without encasing.

Numerical Investigation of Load Carrying Capacity of Geogrid-Encased Stone Columns under Foundation Load (구조물 기초하중 작용시 지오그리드 보강 쇄석말뚝의 하중지지 특성에 관한 수치해석 연구)

  • Yoo, Chung-Sik
    • Journal of the Korean Geotechnical Society
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    • v.25 no.11
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    • pp.75-86
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    • 2009
  • This paper presents the results of a numerical investigation on load carrying capacity of geogrid-encased stone columns to use as load carrying column(s) supporting a foundation load. A validated 3D stress-pore pressure coupled model that can effectively show rapid drainage capability of stone columns and encasement effect of geogrid was adopted and a parametric study was carried out on a number of influencing factors. It is shown that the geogrid encased stone columns can be effectively used as foundation load supporting columns in soft ground. The results of numerical investigation were presented so that the relationship between the load carrying capacity of geogrid-encased stone columns and the influencing factors can be identified. Practical implications of the findings are also discussed.

Behaviour of geogrid reinforced model retaining wall in active failure state by execution of parallel movement (병진이동으로 인한 주동파괴 시 지오그리드 보강토 모델벽체의 거동)

  • Lee, Kang-Man;Kong, Suk-Min;Lee, Dae-Young;Lee, Yong-Joo
    • Journal of the Korean Geosynthetics Society
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    • v.14 no.4
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    • pp.117-127
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    • 2015
  • Recently, there has been a string of negligent accidents for the retaining wall and slope. In order to measure the ground deformation for the MSE wall, the authors carried out the model test to assess behavioral characteristics of geogrid MSE walls in active failure state with different conditions of geogrid reinforcement. The models are built in the soil container box having dimension, 100 cm long, 90 cm height, and 10 cm wide. The reinforcement used in the model test is geogrid (polyvinyl chloride, PVC). Three geogrids are sized by $30cm{\times}60cm$, $30cm{\times}70cm$, $30cm{\times}80cm$ (width ${\times}$ length) respectively. In this study, the laboratory model tests represented for several conditions of the MSE wall, and then its results were compared to 2D FE analysis.

Reinforcement Effectiveness and Arching Effect of Geogrid-Reinforced and Pile-Supported Roadway Embankment (지오그리드로 보강된 성토지지말뚝의 보강 및 아칭효과분석)

  • Shin, Eun Chul;Oh, Young In;Lee, Dong Hyun
    • Journal of the Korean Geosynthetics Society
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    • v.4 no.2
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    • pp.11-18
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    • 2005
  • A pilot scale filed model test and 2-D numerical analysis was conducted to evaluate the effectiveness of constructing a geogrid-reinforced and pile-supported embankment system over soft ground to reduce differential settlement, and the results are presented hearin. Three-by-three pile groups with varying the space between pile were driven into a layer of soft marine clay and a layer of geogrid was used as reinforcement over each pile group. 2-D numerical analysis has been conducted by using the FLAC-2D(Fast Lagrangian Analysis of Continua) program for same condition of field model test. The settlement, vertical stress, and strain of geogrid due to the construction of embankment were measured at various locations. Based on the field model test and numerical analysis results, pile reinforcement generated the soil arching at the midspan of pile cap and the geogrid reinforcement helps reduce the differential settlement of the soft ground by tensile strength of geogrid. Also for $D/b{\geq}6.0$, the effectiveness of geogrid reinforcement in reducing settlement is negligible.

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Evaluation of Installation Damage Factor for Geogrid using Maximum Particle Size of Backfill Material (뒤채움 최대입도를 이용한 지오그리드 보강재의 시공손상계수 산정 방법)

  • Kim, Kyung-Suk;Choi, Young-Chul;Kim, Tae-Soo;Lim, Seoung-Yoon
    • Journal of the Korean Geosynthetics Society
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    • v.6 no.4
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    • pp.29-37
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    • 2007
  • Reduction Factor for Installation Damage required for calculation of design strength of geogrid used in MSEW(mechanically stabilized earth wall) design is usually obtained in the field test simulating real construction condition. However, damages occurred in geogrid during backfill work are influenced by many factors such as polymer types, unit weight per area, backfill construction method and gradation of backfill material and field test considering these factors demands lots of time and costs. In this study, factors affecting installation damage are analyzed and empirical method for evaluating reduction factor for installation damage using maximum particle size in backfill material is suggested.

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Wide-Width Tensile Strength Properties of Geogrids according to Specimen Length and Testing Speed (시료크기 및 인장속도에 따른 지오그리드의 광폭인장강도 평가)

  • Cho, Sam-Deok;Lee, Kwang-Wu;Oh, Se-Yong
    • Journal of the Korean Geosynthetics Society
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    • v.6 no.2
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    • pp.21-26
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    • 2007
  • The tensile properties of geogrid are affected by such factors as temperature, specimen length, gauge length, testing speed and measuring equipment. The tensile strength of geogrids can be determined by ASTM 06637 and ISO 10319. The main differences between two testing methods are testing speed and specimen length. This paper presents the results of the wide-width tensile tests for three geogrids according to different specimen length and tension speed.

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