Journal of the Korean Geosynthetics Society (한국지반신소재학회논문집)

Korean Geosynthetics Society (한국지반신소재학회)
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Installation Damage Reduction Factor for Geosynthetics Reinforcements Based on Various Full-Scale Field Installation Tests

다양한 현장내시공성시험에 근거한 토목섬유 보강재의 시공성 감소계수 평가

  • Cho, Sam-Deok (Department of Infrastructure Safety Research, Korea Institute of Civil engineering and building Technology) ;
  • Lee, Kwang-Wu (Department of Infrastructure Safety Research, Korea Institute of Civil engineering and building Technology)
  • Received : 2018.11.14
  • Accepted : 2018.12.17
  • Published : 2018.12.30
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Abstract

In this paper, to investigate the influence of installation damage, a variety of full-scale field installation tests with 15 geosynthetics reinforcements and fill materials of various grain size distribution have been performed. The full-scale field installation test was conducted with reference to the FHWA (2009) guidelines. The tensile strength tests were performed by sampling up to 20 specimens randomly from the excavated geosynthetics reinforcements after compaction of fill material, and the degree of decrease in tensile strength of reinforcements due to compaction was analyzed based on the experiment results. It was found that the degree of tensile strength reduction of geosynthetics reinforcements due to the compaction of fill material is greatly influenced by the type of reinforcement and the maximum diameter of fill material. In addition, it was found that the strength reduction ratio of PET geogrid (PVC coating) with relatively small stiffness was greatest, and that the larger the maximum grain size of the fill material, the greater the strength reduction ratio. And also, a more reasonable evaluation method for the installation damage reduction factor of geosynthetics reinforcements is proposed based on the results of full-scale field installation tests in present study and the existing test results.

본 연구에서는 토목섬유 보강재의 시공중 손상 정도를 규명하기 위하여 국내에서 많이 사용되고 있는 주요 토목섬유 보강재 제품(7개 사의 15 종류)을 대상으로 다양한 입도의 성토재료를 적용한 현장내시공성시험을 수행하였다. 현장내시공성시험은 FHWA(2009) 지침을 참조하여 수행하였으며, 다짐시공 후 추출된 토목섬유 보강재 시료에서 인장강도 시편(크기 $0.2m{\times}1.4m$)을 최대 20개 이상 균등하게 샘플링하여 인장강도시험을 수행함으로써 시공에 따른 인장강도 감소 정도를 분석하였다. 분석 결과, 성토재료의 다짐시공으로 인한 토목섬유 보강재의 인장강도 감소 정도는 토목섬유 보강재의 종류와 성토재료의 최대입경에 크게 영향을 받으며, 비교적 강성이 작은 PET 결합형 지오그리드(PVC 코팅)의 인장강도 감소율이 가장 크게 나타났고, 전반적으로 성토재료의 최대입경이 클수록 인장강도 감소율은 더욱 크게 나타남을 알 수 있었다. 또한, 이 시험결과와 함께 기 수행된 현장내시공성시험 결과들을 분석하여 토목섬유 보강재의 시공성 감소계수를 보다 합리적으로 평가할 수 있는 방안을 제시하였다.

Keywords

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Fig. 1. Tensile strength test for geosynthetic reinforcement specimens

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Fig. 2. Particle size distribution curnes of filling soils in test site

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Fig. 3. Cross sectional view of field installation test

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Fig. 4. Pictures of field installation test (Gwangyang site)

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Fig. 5. Tensile strength reduction ratio of geosynthetic reinforcements used in field installation test (Gwangyang site)

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Fig. 6. Tensile strength reduction ratio of geosynthetic reinforcements used in field installation test (Yeoncheon site)

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Fig. 7. Installation damage reduction factor of the PET geogrids

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Fig. 8. Installation damage reduction factor of the HDPE geogrids

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Fig. 9. Installation damage reduction factor of the geosynthetic strips

Table 1. Geosynthetics reinforcements used in field installation tests

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Table 2. Installation damage reduction factor of geogrids with the type of filling soil (Cho et al., 2005a)

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Table 3. Comparison of installation damage reduction factor for PET geogrids (coating type) (max. grain size of filling soil : 60mm)

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