• Title/Summary/Keyword: geogrid-reinforcement

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Behaviors of Artificial Reef Reinforced with Settlement Reduction Reinforcement (침하 저감용 보강재로 보강된 인공어초 설치 지반의 거동 특성)

  • Yun, Daeho;Kim, Yuntae
    • Journal of the Korean Geosynthetics Society
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    • v.18 no.1
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    • pp.1-9
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    • 2019
  • This study investigated settlement and scouring characteristics of artificial reef reinforced with various reinforcement types to reduce settlement and scouring. Three reinforcement types were prepared: geogrid, geogrid-bamboo mat (GBM) and seaweed-pile mat (SPM). Various laboratory tests such as bearing capacity test, large size settlement test, two-dimensional flow scour test were performed according to different soil types (sand, silt, clay). Laboratory test results indicated that bearing capacity of seabed with a reinforced artificial reef increased and its settlement and scour depth reduced for all reinforcement types. Especially, reinforcement effect tends to be greater in clay soft ground rather than sand and silt grounds.

Case Study of Geogrid Reinforcement in Runway of Inchon International Airport (지오그리드를 활용한 인천국제공항 활주로 보강사례)

  • 신은철;오영인;이규진
    • Proceedings of the Korean Geotechical Society Conference
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    • 1999.11c
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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 $m^2$.

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Ultimate Bearing Capacity of Strip Foundation on Geogrid -Reinforced Clayey Soil

  • Shin, Eun-Chul;Choi, Chan-Yong
    • Geotechnical Engineering
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    • v.13 no.3
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    • pp.77-86
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    • 1997
  • Laboratory model test results for the ultimate bearing capacity of a surface strip foundation supported by a near-saturated clayey soil reinforced with layers of geogrid have been presented. The optimum values for the width of the reinforcement layers, the depth of reinforcement, and the location of the first layer of geogrid for mobilization of maximum bearing capacity have been determined. Based on the model test results, an empirical procedure to estimate the ultimate bearing capacity has been developed.

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Assessments of the Combined Effect of Installation Damage and Creep on the Long-Term Design Strength of Geogrid for Railroad Reinforcement (철도노반 보강용 지오그리드의 크리프 및 손상이 장기 인장강도에 미치는 영향평가)

  • Lee Do-Hee;Park Tae-Soon;Cho Sam-Deok;Lee Kwang-Wu
    • Proceedings of the KSR Conference
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    • 2004.10a
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    • pp.1156-1161
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    • 2004
  • The factors affecting the long-term design strength of geogrid for railroad reinforcement 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 geogrid. 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. In this study, a series of field tests are carried out to assess installation damage of a various geogrids according to different fill materials, and then creep tests are conducted to assess the creep properties of both undamaged and damaged geogrids.

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Troubles and Countermeasures of Geogrid-Reinforced Earth Wall (지오그리드 보강토 옹벽의 설계/시공에 따른 문제점과 대책방안)

  • 조삼덕
    • Proceedings of the Korean Geotechical Society Conference
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    • 2001.10a
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    • pp.315-321
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    • 2001
  • Since 1984, block-type reinforced earth wall with geogrid reinforcement has been widely used for retaining wall applications till now in Korea. The use of geogrid as a reinforcement in the reinforced earth wall is steadily increased in an amount over 1,500,000㎡ in a year However, still need exists that some problems in design and construction practices should be made to review, Therefore, this paper reviewed reasonable criteria for selection of backfills, design details considering the effect of the upper soil slope on reinforced earth wall, horizontal displacement of facing block during compaction, and the damage of geogrid reinforcements on the edge part of facing block. Finally, alternative methods of measures on those problems are proposed.

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A laboratory and numerical study on the effect of geogrid-box method on bearing capacity of rock-soil slopes

  • Moradi, Gholam;Abdolmaleki, Arvin;Soltani, Parham;Ahmadvand, Masoud
    • Geomechanics and Engineering
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    • v.14 no.4
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    • pp.345-354
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    • 2018
  • Currently, layered geogrid method (LGM) is the commonly practiced technique for reinforcement of slopes. In this paper the geogrid-box method (GBM) is introduced as a new approach for reinforcement of rock-soil slopes. To achieve the objectives of this study, a laboratory setup was designed and the slopes without reinforcements and reinforced with LGM and GBM were tested under the loading of a circular footing. The effect of vertical spacing between geogrid layers and box thickness on normalized bearing capacity and failure mechanism of slopes was investigated. A series of 3D finite element analysis were also performed using ABAQUS software to supplement the results of the model tests. The results indicated that the load-settlement behavior and the ultimate bearing capacity of footing can be significantly improved by the inclusion of reinforcing geogrid in the soil. It was found that for the slopes reinforced with GBM, the displacement contours are widely distributed in the rock-soil mass underneath the footing in greater width and depth than that in the reinforced slope with LGM, which in turn results in higher bearing capacity. It was also established that by reducing the thickness of geogrid-boxes, the distribution and depth of displacement contours increases and a longer failure surface is developed, which suggests the enhanced bearing capacity of the slope. Based on the studied designs, the ultimate bearing capacity of the GBM-reinforced slope was found to be 11.16% higher than that of the slope reinforced with LGM. The results also indicated that, reinforcement of rock-soil slopes using GBM causes an improvement in the ultimate bearing capacity as high as 24.8 times more than that of the unreinforced slope.

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.

Experimental Study on the Reinforcement Effect of Geogrid in Soft Ground Improvement (연약지반 개량시 지오그리드 보강효과에 관한 실험적 연구)

  • Ham, Hyeon-Su;Lee, Sang Duk
    • Journal of the Korean Geosynthetics Society
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    • v.17 no.2
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    • pp.1-7
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    • 2018
  • The number of construction of roads and railroads in soft ground such as coastal areas and wetlands is getting increased. For this reason cases that soft ground improvement is applied are increasing. In general, many ground improvement methods consider only the working conditions at the time or only economy. But if the working condition and economy are taken into consideration together, the number of applicable construction method gets limited. In such a case, a ground improvement method using both the surface layer portion and the deep layer portion is applied. But the basic research on this is still insufficient in practice. Therefore, in this study the reinforcement effect of geogrid was investigated by carrying out the model test realizing the case in which soft surface ground improvement and depth improvement are simultaneously applied. And it was intened to understand the effect of the thickness of surface layer, the diameter and length of the improvement body on the reinforcement effect of geogrid. The result showed that the effect of the surface layer thickness is greater than the effect of the deep layer diameter. Moreover, when the surface layer is reinforced with a geogrid, the strength of the surface layer part is enhanced and this effect of a geogrid reinforcement caused the reduction of surface settlement.

Evaluation of Geogrid-Reinforced Subbase Layer Thickness of Permeable Flexible Pavements based on Permanent Deformation Model (지오그리드로 보강된 투수성 연성포장 보조기층제 영구변형을 고려한 층두께 산정 비교 연구)

  • Kwon, Hyeok Min;Oh, Jeongho;Han, Shin-In
    • International Journal of Highway Engineering
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    • v.17 no.1
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    • pp.69-75
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    • 2015
  • PURPOSES : The objective of this study is to evaluate the effectiveness of a geogrid reinforced subbase of permeable flexible pavement structures with respect to permanent deformation. METHODS : Experimental trials employing a repeated triaxial load test scheme were conducted for both a geogrid reinforced subbase material and a control specimen to obtain the permanent deformation properties based on the VESYS model. Along with this, a finite element-based numerical analysis was conducted to predict pavement performance with respect to the rutting model incorporated into the analysis. RESULTSAND CONCLUSIONS : The results of the experimental study reveal that the geogrid reinforcement seems to be effective in mitigating permanent deformation of the subbase material. The permanent deformation was mostly achieved in the early stages of loading and then rapidly reached equilibrium as the number of load applications increased. The ultimate permanent deformation due to the geogrid reinforcement was about 1.5 times less than that of the control specimen. Numerical analysis showed that the permeable, flexible pavement structure with the geogrid reinforced subbase also exhibits less development of rutting throughout the service life. This reduction in rutting led to a 20% decrease in thickness of the subbase layer, which might be beneficial to reduce construction costs unless the structural adequacy is not ensured. In the near future, further verification must be conducted, both experimentally and numerically, to support these findings.

Model Tests on the Behavior of Geogrid Reinforced Soil Walls with Vertical Spacing of Reinforcement Layers (보강재 설치 간격에 따른 지오그리드 보강토옹벽의 변형거동에 관한 모형실험)

  • 조삼덕;안태봉;이광우;오세용
    • Journal of the Korean Geotechnical Society
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    • v.20 no.5
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    • pp.109-116
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    • 2004
  • The model tests are conducted to assess the behavior characteristics of geogrid reinforced soil walls according to different surcharge pressures and reinforcement spacings. The models are built in the box having dimension, 100cm tall, 140cm long, and 100cm wide. The reinforcement used is geogrid(tensile strength 2.26t/m). Decomposed ganite soil(SM) is used as a backfill material. The strain gauges and LVDTs are Installed to obtain the strain in the reinforcements and the displacements of the wall face. From the results, it can be concluded that the more the reinforcement tensile strength increases, the more the wall displacements and the geogrid strains decreases. The maximum wall displacements and geogrid strains of the model walls occur due to the uniform surcharge pressure at the 0.7H from the bottom of the wall. The horizontal displacements of the wall face nonlinearly increase with the increase of surcharge pressures, and this nonlinear behavior is significantly presented for larger surcharge due to the nonlinear tensile strength-strain relationship of the reinforcements.