• 한국환경복원기술학회지
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• 제8권1호
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• pp.27-36
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• 2005

Geosynthetic reinforcements may be damaged during its installation in the filed. The installation damage mainly depends on two factors such as materials used and construction activities. This paper describes the results of a series of field tests, which are conducted to assess the installation damage of geogrid according to different maximum grain sizes of fills (40, 60, and 80 mm). These tests are done in three sites for twelve different kinds of geogrids. After field tests, the changes in tensile strength of the geogrids is determined from wide width tensile tests using both damaged and undamaged specimens. In the results of tests, tensile strength of the relatively flexible geogrids after field installation tests was decreased about from 20% to 40% according to the increment of the maximum grain size. On the other hand, for the relatively stiff geogrids, the loss of the tensile strength after site installation was examined below 5.2% independent of the maximum grain size of the soils. The results of this study show that the installation damage significantly depends on the stiffness of geogrid and is more obvious to a flexible geogrid and a fill material having higher maximum grain size.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 토목섬유 학술발표회 논문집
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• pp.105-116
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• 1999

The Inchon International Airport site was formed by reclaimed soil from the sea. The average thickness of soft soil Is about 5 m and most of soft soils are normally consolidated or slightly over consolidated. There are many box culverts which are being constructed under the runways in the airfield. Sometimes, differential settlement can be occurred in the adjacent of box culvert or underground structures at the top layer of runway Soil compaction at very near to the structure is not easy all the time. Thus, one layer of geogrid was placed at the bottom of lean concrete layer for the concrete paved runway and at the middle of cement stabilized sub-base course layer for the asphalt paved runway. The length of geogrid reinforcement is 5m from the end of box culvert for both sides. The extended length of geogrid was 2m from the end of backfill soil in the box culvert. The tensile strength tests of geogrid were conducted for make sure the chemical compatibility with cement treated sub-base material. The location of geogrid placement for the concrete paved runway was evaluated. The construction damage to the geogrid could be occurred. Because the cement treated sub-base layer or lean concrete was spread by the finisher. The magnitude of tensile strength reduction was 1.16%~1.90% due to the construction damage and the ultimate tensile strength is maintained with the specification required. Total area of geogrid placement in this project is about 50,000 $m^2$.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.978-985
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• 2004

Geogrid may be damaged during its installation in the filed. The installation damage mainly depends on two factors, which are materials used and construction activities. Materials relate to geogrid and soils, and construction activities are mainly related to installation of geogrid and compaction of soils. This paper describes the results of a series of field tests, which were conducted to assess the installation damage of the various geogrids according to different fill materials. After field installation damage tests, the change in tensile strength of geogrids was determined from wide width tensile tests using both damaged and undamaged specimens.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.958-967
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• 2004

This paper deal with cause and analysis about case of collapsed reinforced-soil retaining wall. The analysis of the cause was carried through experimentation, slop stability analysis and literature study. The experimentation treated the large direct shear test, the hydraulic conductivity test and the other basic test through backfill extracted from collapsed reinforced-soil retaining wall. The ultimate tensile strength was established by rib tensile strength test of geogrid. The analysis of internal and external stability of reinforced-soil retaining wall was performed on the basis of parameters. The result of analysis, reinforced-soil retaining wall and the slope at the dry season are stable. However, the factors that fine-grained soil at hydrometer test exceed the standard of the design, rainfall duration is too long at the time of collapse and monthly pricipitation is heavy are cause of the collapse.

• 한국지반환경공학회 논문집
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• 제13권2호
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• pp.83-93
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• 2012

보강토옹벽은 1980년대 초반 국내에 도입된 이래로, 다양한 금속 혹은 토목섬유 보강재가 개발되어 현장에 적용되고 있으며, 특히, 국내에서는 지오그리드가 가장 많이 적용되고 있다. 이에 본 연구에서는 현재 국내에서 생산되고 있는 4가지 종류의 지오그리드에 대해 인장강도-인장변형 관계 특성을 고찰하였다. 또한 재질 및 제조방식이 상이한 3가지 지오그리드에 대해서는 일련의 광폭인장강도시험을 수행하여 실제 지오그리드 인장변형과 변형률계에 의해 측정된 인장변형을 비교하였다. 실험결과, 변형률계에 의해 측정된 인장변형률이 광폭인장강도시험기에 의해 측정된 실제변형률 보다 다소 큰 경향을 보이나 인장변형률이 3% 보다 작은 경우에는 측정방법에 따른 차이가 거의 없는 것으로 확인되었다.

• 한국지반신소재학회논문집
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• 제6권1호
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• pp.27-32
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• 2007

본 연구에서는 기존의 보강토 옹벽의 주요부재인 블록과 지오그리드간의 문제점인 파손을 최소화하고 배면지반의 수직변위를 허용한 I형 연결판을 사용해 적용성을 살펴보았다. 접속방법의 변화로 지오그리드를 약 700mm경감시킬 수 있었으며, 실내역학 실험을 통해 연결부의 연결강도는 실험에 사용한 지오그리드의 최대광폭인장강도의 53%로 나타났다. 이는 실내실험의 한정된 모사로 인한 결과로 현장조건에서 지지부재의 역할을 고려할 때 우수한 연결강도를 나타낼 수 있을 것으로 판단된다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 토목섬유 학술발표회 논문집
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• pp.21-38
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• 1999

Engineering properties of most polymers used in geosynthetics such as geogrid can be degraded by the chemical reaction (e.g., oxidization, ultraviolet rays, hydrolysis etc.), chemical and mechanical load, microorganism, and so on. In addition, polymer can be damaged by the compaction during construction, and the characteristic of tensile strength of polymer can be changed by the long-term creep effect. In this study, engineering properties of flexible geogrids which are manufactured by weaving/knitting the high-tenacity polymers such as polyester formed in a very open, grid-like configuration, coated with any one of a number of materials (e.g., PVC, latex, etc.), are investigated. Through the analysis of test results, the durability and the long-term design tensile strength of flexible geogrids are evaluated.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.561-568
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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 reinforced soil is to calculate the long-term design strength of a reinforcement damaged during installation by multiplying the two partial safety factors, $RF_{ID} and RF_{CR}$. This method assumes that there is no synergy effect between installation damage and creep deformation of geogrids. Therefore, this paper describes the results of a series of experimental study, which are carried out to assess the combined effect of installation damage and creep deformation for the long-term design strength of geogrid reinforcement. The results of this study show that the tensile strength reduction factors, RF, considering combined effect between installation damage and creep deformation is less than that calculated by the current design method.

• 한국지반공학회논문집
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• 제20권5호
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• pp.109-116
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• 2004

상재하중 및 보강재의 포설 간격이 보강토옹벽의 변형거동에 미치는 영향을 평가하기 위하여 일련의 모형실험을 수행하였다. 모형 보강토옹벽은 $100cm \times 140 \times 100cm$ 크기의 모형토조내에 축조하였다. 본 모형실험에서는 보강재로 인장강도 2.26t/m의 지오그리드를 사용하였고, 뒤채움흙으로는 통일분류법상 SM에 해당되는 화강풍화토를 사용하였다. 모형옹벽 축조후 상재하중 재하에 따른 벽체수평변위와 보강재의 인장변형을 측정하였다. 실험결과, 상재하중이 증가할수록 모형 보강토옹벽의 벽체변위 및 보강재 인장력이 증가하였다. 벽체 최대수평변위 및 보강재 최대 인장력은 벽체 하단으로부터 0.7H 지점에서 측정되었으며, 그 크기는 상재하중이 증가할수록 변형증가율이 커지는 비선형적인 형태를 보였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.372-379
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• 2004

The model tests were conducted to assess the behavior characteristics of geogrid reinforced earth walls according to various surcharge loads and reinforcement spacing. The models were built in the box having dimension, 100cm tall, 140cm long, and 100cm wide. The reinforcement used was geogrid(tensile strength 2.26t/m). Decomposed granite soil(ML) was used as a backfill material. The LVDTs were installed on the model retaining walls to obtain the displacements of the facing. In the results, the maximum displacement of facing and tensile strain of geogrid was measured at 0.7H(H is wall height) from the bottom of reinforced wall.