• Title, Summary, Keyword: 지오그리드

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Investigation on Support Mechanism of Geogrid-Encased Stone Columns in Soft Ground (연약지반에 시공되는 지오그리드 감쌈 스톤컬럼의 하중 지지 메카니즘에 관한 연구)

  • Yoo, Chung-Sik;Kim, Sun-Bin
    • Journal of the Korean Geotechnical Society
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    • v.24 no.12
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    • pp.93-101
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    • 2008
  • This paper presents the results of numerical investigation on support mechanism of geogrid-encased stone columns for use in soft ground improvement. A number of cases were analyzed using a 3D stress-pore pressure coupled model that can effectively model construction sequence and drainage as well as reinforcing effects of geogrid-encased stone columns. The results indicated that the geogrid encasement provides additional confinement effect that reduces vertical stress in the soft ground, thus resulting in less excess pore water pressures and associated settlement. Also revealed was that such a confinement effect depends on encasement length and stiffness of geogrid. It is also shown that there exist critical encasement length and stiffness of geogrid for a given condition.

Load Carrying Capacity of Geosynthetic-Reinforced Stone Column in Cohesionless Ground (사질토 지반에 시공되는 지오그리드 보강 쇄석말뚝의 지지력 거동특성)

  • Yoo, Chung-Sik;Song, Ah-Ran;Kim, Sun-Bin;Lee, Dae-Young
    • Journal of the Korean Geotechnical Society
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    • v.23 no.5
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    • pp.15-27
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    • 2007
  • This paper deals with the bearing capacity behaviour of geosynthetic-reinforced stone column(GRSC) constructed in soft ground, as part of an investigation regarding the applicability of GRSC in Korea. In this study, two-dimensional finite element analyses were performed to investigate the effect of relevant design factors on the bearing capacity behaviour. The parametric study is performed for various influencing factors. The results indicated that the geogrid encasement tends to significantly improve the load carrying capacity of a stone column. Also found were that the geogrid encasement length and its stiffness significantly affect the load carrying capacity behaviour of GRSC, and that the encasement length of three times the stone column diameter is sufficient in mobilizing the full reinforcement effect. Practical implications of the findings are discussed.

Application of Stepped Isothermal Methods to Lifetime Prediction of Geogrids (SIM을 적용한 성토보강용 지오그리드의 수명예측)

  • Koo, Hyun-Jin;Kim, You-Kyum;Kim, Dong-Whan
    • Journal of the Korean Geosynthetics Society
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    • v.4 no.1
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    • pp.3-6
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    • 2005
  • The failure of geogrids can be defined as an excessive creep strain which causes the collapse of slopes and embankments. In this study, the lifetime of knitted polyester geogrids was predicted by using SIM(Stepped Isothermal Methods using TTS principal) and statistical data analysis techniques. The results indicate that the creep strain was 8.74, 8.79, 8.80% with 2.16~2.20% of CV% at 75, 100, 114 years, respectively and the creep strain reaches 9.3% after 100 years of usage at $27^{\circ}C$ which meets the required lifetime(creep strain less than 10% after 100 years of usage) in the fields. The SIM method is shown to be effective in reduction of uncertainty associated with inherent variability of multi-specimen tests and shorter test times than conventional TTS(Time-Temperature Superposition).

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Evaluation of Geogrid-Reinforced Track substructure Effectiveness Using A Large-Scale Pullout Device (대형인발시험기를 이용한 지오그리드로 보강된 궤도하부구조층의 효율성 평가)

  • Oh, Jeongho
    • Journal of the Society of Disaster Information
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    • v.10 no.1
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    • pp.40-48
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    • 2014
  • A number of attempts has been made to reinforce ballasted track substructure to meet the requirement of high-speed operation and effective rehabilitation of existing railroads. For the purpose of this, the use of geogrid has been applied, and the benefit of its use has been recognized via previous studies. In this study, an experimental pullout test was carried out to investigate the influence of normal stress on pullout strength of geogrid using different types of soil and geogrid. The results revealed that the pullout resistance generally tends to increase proportional to normal stress while the pullout coefficient interaction decreases, which is a function of material interface properties, such as the friction angle of soil, and interlocking condition between soil and geogrid. In addition, a methodology based on work-energy concept was proposed to evaluate effectiveness of geogrid and limitedly verified using test results.

Pullout Characteristics of Waste Fishing Net Reinforced Bottom Ash using Pullout Test (인발시험에 의한 저회에 보강된 폐어망의 인발특성 연구)

  • Kwon, Soon-Jang;Kim, Yun-Tae
    • Journal of the Korean Geosynthetics Society
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    • v.12 no.4
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    • pp.57-66
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    • 2013
  • In this study, pullout tests were carried out to evaluate pullout characteristics of waste fishing net (WFN), which added into bottom ash for recycling both bottom ash and WFN. Three different mesh size of WFN (WFN20:$20mm{\times}20mm$, WFN30:$30mm{\times}30mm$, WFN40:$40mm{\times}40mm$) and geogrid were added as a reinforcement. Pullout characteristics of waste fishing net were compared with those of the geogrid. Pullout test results showed that pullout strength and stiffness of WFN20 are a little less than those of geogrid. However, the pullout friction angle of WFN20 is similar to that of geogrid due to bearing resistance induced from transverse rib because thickness of WFN20 is greater than geogrid. Pullout test results also indicated that distribution of residual strain along reinforcement after test depends on overburden stress. Residual strain at the tip of reinforcement increased with an increase in overburden stress due to concentration of pullout force on the tip of reinforcement.

Pullout Characteristics of Geogrid with Attached Passive Reinforcement (마찰돌기를 부착한 지오그리드의 인발특성 평가)

  • Moon, Hongduk;Yoo, Chulho
    • Journal of the Korean Geoenvironmental Society
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    • v.15 no.11
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    • pp.43-51
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    • 2014
  • In this study, a series of pullout experiments were conducted on geogrid with attached passive reinforcement with respect to silt containments. Experiments were performed on man-made sand ground containing different silt of 0 %, 17 %, 35 % under various normal stresses 30 kPa, 60 kPa, 120 kPa respectively. The pullout test results showed that passive reinforcement increased the pullout strength over all silt contained condition and showed up to 20 % increases for same soil condition. The test results converted to the coefficient of interaction of pullout test to investigate the effect of reinforcement and the case of passive reinforcement showed 0.7~1.6 distribution depend on a silt contents. Therefore it is concluded that the overall length of geogrid can be reduced under the low vertical stress conditions.

Load Carrying Capacity and Failure Mechanism of Geogrid Reinforced Stone Columns : Reduced-Scale Model Tests (지오그리드 보강 Stone Column의 파괴메카니즘 및 지지력 특성 - 축소모형실험을 통한 고찰)

  • Lee, Dae-Young;Song, Ah-Ran;Yoo, Chung-Sik
    • Journal of the Korean Geotechnical Society
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    • v.22 no.10
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    • pp.121-129
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    • 2006
  • Stone column is one of the ground improvement systems which is being used for accelerating consolidation and increasing bearing capacity for settlement sensitive structures like load embankments, bridge abutments, oil storage tanks etc. The effects of this method are enhancement of ground bearing capacity, reduction of settlement, prevention of liquefaction and prevention of lateral ground movement. Recently, geosynthetic reinforced (encased) stone column approach has been developed to improve its load carrying capacity through increasing confinement effect. Although such a concept has successfully been applied in practice, fundamentals of the method have not been fully explored. This paper presents the results of an investigation on the bearing capacity and failure mechanism of geogrid-encased stone column by model tests. The results of the analyses indicated improved bearing capacity of the geogrid reinforced stone column method over the conventional strone column method with no encasing.

Bearing Capacity of Strip Foundation on Geogrid-Reinforced Sand with Embedment Depth (기초의 근입깊이를 고려한 지오그리드 보강 사질토지반의 지지력)

  • ;Shin, Dong-Hoon;Oh, Young-In
    • Journal of the Korean Geotechnical Society
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    • v.16 no.3
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    • pp.57-65
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    • 2000
  • 다층의 지오그리드로 보강된 사질토 지반에 축조된 줄기초의 극한 지지력을 결정하기 위하여 실내모형실험을 실시하였다. 한가지 종류의 사진토와 지오그리드를 사용하였으며, 시험은 기초의 근입깊이(Df)가 없을 때와 근입깊이(Df)가 있을 때로 분류하여 시행되었다. 기초의 근입깊이(Df)는 기초의 폭(B)보다 작도록 제한되었다. 시험결과, 주어진 보강깊이의 두께에 대하여 지지력비(BCR)는 기초의 근입깊이(Df)가 0보다 클 때 증가하였다.

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Analysis and Prediction of Deformation Behaviors of Geogrids by FEM (FEM에 의한 지오그리드의 변형거동 해석 및 예측)

  • Jeon, Han-Yong;Jang, Yeon-Soo;An, Byoung-Wook
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.1604-1613
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    • 2008
  • 지오그리드란 토목합성보강재의 한 종류이며, 지반의 보강 처리를 위해 주로 사용된다. 본 연구에서는 유한 요소해석프로그램에 의한 지오그리드의 접점강도, 응력분산효과해석과 광폭인장강도 평가 개선을 위한 방법에 관한 연구를 주목적으로 하였다. 이 때 범용 유한요소 해석 프로그램인 VisualFEA/Edu를 사용하였으며, 실제 실험값과 프로그램의 결과 값의 비교를 통하여 해석모델의 타당성을 검증하였다.

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An Experimental Evaluation for Geotechnical Properties of Geosynthetic composites by Direct Shear Test (전단시험에 의한 토목섬유 보강재의 지반 적용성 평가)

  • 조성호;최세환;차동환;류중재;전한용
    • Proceedings of the Korean Fiber Society Conference
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    • pp.267-270
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    • 2003
  • 일반적으로 토목 공사에서 구조의 보강 용도로 주로 사용되는 지오그리드(geogrids)는 우수한 인장 탄성계수와 인장강력을 지니고 있어서 하중이 집중적으로 작용하는 토목 구조물에서 보강기능을 원활히 수행하는 보강재료 이지만, 비교적 큰 격자상 외관 구조를 가지므로 지오그리드를 관통하는 각종 물질, 특히 함유 수분과 세립질 토양의 이동이나 유실 등을 효과적으로 제어하지 못한다는 단점도 있어 사용상의 제약이 있다. (중략)

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