• Title/Summary/Keyword: Geosynthetic

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A Study on the Improvement Mechanical Properties of Geosynthetic Interface (토목섬유 접촉면의 역학적 특성 개선에 관한 연구)

  • Nam, Yong;Kim, Gwangho;Kwon, Jeonggeun;Im, Jongchul;Seo, Jeochan
    • Journal of the Korean GEO-environmental Society
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    • v.11 no.3
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    • pp.23-32
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    • 2010
  • In this study, Generally sandbag was used to reinforce slope or restore levee by using the in-situ material. To increase shear strength of sandbag, the Velcro system was effective for geosynthetic interface and make up for the weakness of shear strength between sandbag to sandbag. In this study, shear properties of geosynthetic-geosynthetic and geosynthetic-soil were evaluated from large scale direct shear tests. The cohesion and the angle of internal friction of each interface was evaluated. And laboratory model tests were performed to compare strength of reinforcement with strength of none reinforcement. As a result of this study, the cohesion and the angle of internal friction of each interface was increased, especially the cohesion was increased more than the angle of internal friction. Also according to the result of model test, the bearing capacity was increased by 20%.

Behavior of Geosynthetic Reinforced Modular Block Walls under Sustained Loading using Reduced-Scale Model Test (축소모형실험에 의한 지속하중하에서의 보강토 옹벽의 거동특성 연구)

  • Yoo, Chung-Sik;Kim, Sun-Bin;Byun, Joseph;Kim, Young-Hoon;Han, Dae-Hui
    • Journal of the Korean Geosynthetics Society
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    • v.5 no.1
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    • pp.1-7
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    • 2006
  • Despite a number of advantages of reinforced earth walls over conventional concrete retaining walls, there exit concerns over long-term residual deformation when used as part of permanent structures. In view of these concerns, time-dependant deformation characteristics of geosynthetic reinforced modular block walls under sustained loads were investigated using reduced-scale model tests. The results indicated that a sustained load can yield appreciable magnitude of residual deformation, and that the magnitude of residual deformation depends on the loading characteristic as well as reinforcement stiffness.

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Pullout Resistance by Horizontal Spacing of Geosynthetic Strip (띠형 섬유보강재의 설치간격에 따른 인발저항 특성에 관한 연구)

  • Han, Jung-Geun;Yoon, Won-Il;Hong, Ki-Kwon;Lee, Kwang-Wu;Kim, Ju-Hyong;Cho, Sam-Deok
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.09a
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    • pp.315-324
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    • 2010
  • In this study, the pullout tests are conducted to evaluate the pullout resistance of the geosynthetic strip with or without bearing resistance zone. The test results are indicated that the pullout resistance of the geosynthetic strip without bearing resistance zone is not affected by horizontal spacing. However, the horizontal spacing of reinforcement with bearing resistance zone affects the bearing resistance. In other words, it is indicated that the bearing resistance at spacing of 210mm is larger than that at spacing of 260mm. This means that the pullout strength at spacing of 210mm is larger than that at spacing of 260mm. Therefore.

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Model to Determine Long-term Allowable Strength of Geosynthetics Reinforcements Considering Strain Compatibility (변형률 적합성을 고려한 토목섬유 보강재의 장기허용강도 결정 모델)

  • Jeon, Han-Yong;Yuu, Jung-Jo;Mok, Mun-Sung
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.03a
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    • pp.1580-1587
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    • 2005
  • To calculate the long-term allowable strength of geosynthetic reinforcement, replacement method was recommended. The isochronous creep curve by S. Turner was used to define the relation between creep strain and allowable strength. In isochronous curve at given time, one can read the allowable strength at allowable creep strain. The allowable strain gets from specification by directors or manufacturers according to the allowable displacement of reinforced structures. The allowable strength can be determined in relation to the allowable horizontal displacement each structures case by case. The effect of install damage on isochronous behaviors of geosynthetic reinforcement was little. In previous study, install damage increase the creep strain slightly. And the degradation was not identified. But it is supposed that degradation increase the creep strain. In conclusion, The recommended model to determine long-term allowable strength of geosynthetic reinforcements considering tensile deformation of reinforcement and soil is fit for proper, correct and economic design for reinforced earth walls.

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A Case Study on Design of Geosynthetic-Reinforced Segmental Retaining Walls (다단식 보강토 옹벽 설계사례에 관한 고찰)

  • Park, Si-Sam;Cho, Sam-Deok;Park, Du-Hee;Chang, Ki-Soo
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.10a
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    • pp.168-175
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    • 2008
  • The method of reinforced earth walls has grown remarkably and the frequency of utilization has been increased on a national scale thereafter introduced in the middle 1980s in Korea. Furthermore the construction case of the extensive Geosynthetic-Reinforced Segmental Retaining Walls had been increased. Currently, the design criterion of FHWA and NCMA mainly used in Korea suggest determining the horizontal distance of the upper/lower retaining wall based on the study results of the internal stability and the external stability of Segmental Retaining Walls but in many cases are not suitable for the actual situation in Korea. Therefore, in this study reviewed the design criterion of Geosynthetic-Reinforced Segmental Retaining Walls, performed the internal and external stability in Paju, Gyeonggi-do based on the design criterion of FHWA and NCMA, suggested the modified design criterion of FHWA with analyzing the results, and performed the stability analysis for the internal and external stability and the compound failure. Moreover for the confirmation of the modified FHWA design standard, the suggestion and the analysis of the numerical analysis approaching method using shear strength reduction technique were performed and the design cases utilized the modified FHWA design standard based on the study analysis were introduced.

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Failure Mechanism of Geosynthetic-Reinforced Segmental Retaining Wall in a Tiered Configuration (계단식 보강토옹벽의 파괴 메카니즘 연구)

  • Yoo, Chung Sik;Jung, Hyuk Sang;Lee, Bong Won
    • Journal of the Korean Geosynthetics Society
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    • v.3 no.4
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    • pp.13-19
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    • 2004
  • This paper presents the results of an investigation on the failure mechanism of geosynthetic-reinforced segmental retaining walls in tiered arrangement using reduced-scale model tests. In this laboratory model tests, a reduced scale model of the full-scale geosynthetic-reinforced wall which was constructed in Geotechnical Experimental Site at Sungkyunkwan University was used to perform a study on the failure mechanism. In order to a high degree of realism, the geometry of the wall and the material properties were selected applying Similitude Laws was used to perform laboratory model tests. And contrary to the previous failure tests with various surcharge pressures, the failure by the tired wall weight was observed. Primary variables considered in the model tests include the different offset distance between the tiers and the different reinforcement length in the lower tier and as a result of the parametric study, a different failure pattern was observed.

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Numerical Investigation on Behavior of Back-to-Back Reinforced Earth Wall (Back-to-Back옹벽의 거동에 관한 수치 해석적 연구)

  • Yoo, Chung-Sik;Kim, Jae-Wang
    • Journal of the Korean Geotechnical Society
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    • v.25 no.12
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    • pp.131-142
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    • 2009
  • Geosynthetic reinforced soil walls are well recognized alternatives to conventional retaining walls due to many advantages in terms of ease of construction, economy, and aesthetics, among others. In recent years, the use of back-to-back (BTB) geosynthetic reinforced soil walls has been increasing for roadway and railway construction. However, there are insufficient studies concerning the behavior of BTB type geosynthetic reinforced soil walls. In this study a series of finite element analysis were performed for BTB walls with various wall geometry and reinforcement distribution. The results were then analyzed to relate the wall geometry and reinforcement distribution and the performance of BTB walls. Optimum reinforcement pattern was also investigated.

The Evaluation of Geosynthetic Clay Liner as a barrier layer for the Final Cover System in landfill (폐기물 매립지 최종복토 차단층으로서 Geosynthetic Clay Liner 적용성 평가)

  • Lee, Jung-Lan;Moon, Chul-Hwan;Jung, Chan-Kee;Lee, Jai-Young
    • Journal of the Korean Geosynthetics Society
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    • v.3 no.2
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    • pp.23-29
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    • 2004
  • One of the most important concern in the design of barrier layer in to protect the water through the landfill. The barrier layer consists of a single compacted clay liner(CCL) or a composite liner with high density polyethylene(HDPE). The construction of barrier layer at the edge of cover system usually has some problems because of steep slope in the landfill. In this study the authors evaluate the geosynthetic clay liner(GCL) as a barrier layer at the edge of the final cover system in landfill. The GCLs were simulated the stability of slope, the HELP(Hydrologic Evaluation of Landfill Performance) and the durability of environmental situation. As the results, the GCL has more stable than the CCL. Therefore, the authors suggest that the GCL in good for the barrier layer of the final cover system in the landfill.

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Experimental Study on Long-Term Performance Evaluation of Geosynthetic Strip Reinforcement (띠형 섬유보강재의 장기성능 평가를 위한 실험적 연구)

  • Lee, Kwang-Wu;Kim, Ju-Hyeung;Cho, Sam-Deok;Han, Jung-Geun;Yoon, Won-Il;Hong, Ki-Kwon
    • Journal of the Korean Geosynthetics Society
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    • v.9 no.4
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    • pp.75-84
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    • 2010
  • In this study, the long-term performance tests, which have extensibility, creep deformation, installation resistance and durability characteristic, is conducted to apply geosynthetic strip in field. The strength reduction factors using the test results are evaluated in order to calculate long-term design tensile strength. First, the creep deformation was evaluated by both the stepped isothermal method(SIM) and the time-temperature superposition(TTS) method. The creep reduction factor is reasonable to apply 1.6. Second, the result of installation damage test had little damage of yarn, which affected strength of reinforcement. Therefore, it can be analyzed that the installation damage of geosynthetic strip has little effect of long-term design tensile strength. Finally, the durability reduction factor considering chemical, biological and outdoor exposure resistance is reasonable to apply 1.1, which is considered the stability and economic efficiency of reinforced earth wall using geosynthetic strip.

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Evaluation of Interface Shear Properties Between Geosynthetics and Soils Through Inclined Board Tests (경사판 시험을 통한 토목섬유와 흙의 접촉 전단 특성 평가)

  • 서민우;신준수;박준범;박인준
    • Journal of the Korean Geotechnical Society
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    • v.19 no.6
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    • pp.285-298
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    • 2003
  • Shear properies of geosynthetic/geosynthetic and geosynthetic/soil interfaces which are widely met in landfill sites were evaluated from the inclined board tests. The inclined board testing apparatus is known to reproduce the shear behavior on the low normal stress most accurately. In this study, the friction angle of each interface was estimated and the tensile force mobilized at the geosynthetic was measured as well. The test results showed that the friction angle of each interface and the tensile force of the geosynthetics depended on the amount of normal stress, the type of the geosynthetics used, and the combinations of geosynthetics and soils. In addition, the sand/geotextile/geomembrane interface system was simulated in this study, and it was observed that the tensile force developed at the geomembrane decreased due to the protection effect of the geotextile located above the geomembrane. The test results of this research was compared with those of direct shear tests published, too. Finally, by comparing the measured tensile force of the geosynthetics when the initial displacement of the box occurs, when the slope is called as the critical slope, with suggested analytic solution, the accuracy of analytic solution and the applicability to design were identified.