• Title, Summary, Keyword: Geogrid

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Evaluation of Long-Term Stability of Geogrids by Reduction Factors of Creep Deformation (크리프 변형 감소인자에 의한 지오그리드의 장기안정성 평가)

  • 전한용;목문성;이웅의;변성원
    • Textile Science and Engineering
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    • v.41 no.1
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    • pp.50-55
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    • 2004
  • Long-term stability of two types of geogrids were evaluated. Membrane drawn type geogrid showed an exponential increase in strength on drawing, while textile type geogrid showed sigmoidal increase. Accelerated creep test was carried out for textile type geogrid but not for membrane drawn type geogrid because of its thermal property. Creep strain for membrane drawn type geogrid was larger than the ultimate tensile strain in tensile tests. Reduction factor from creep deformation of textile type geogrid was smaller than that of membrane type geogrid. From this result, it was seen that the textile type geogrid is more stable than membrane type geogrid in creep deformation.

Bearing Capacity of Strip Footing on Geogrid-Reinforced Soft Ground (지오그리드로 보강된 연약지반 위에 위치한 연속기초의 극한 지지력)

  • 유충식;신승우
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.169-174
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    • 1994
  • This paper presents the results of a parametric study on the bearing capacity behavior of a footing located above geogrid-reinforced ground using the finite element method of analysis. A wide range of boundary conditions were analyzed, with varing geogrid design parameters such as depth of geogrid layer, length and siffness of geogrid, and number of geogrid layer, were analyzed. Based on the results of analysis, the optimum geogrid design parameters were determined, which maximize the reinforcing effect of geogrid reinforcement for a given conidition. Furthermore, the mechanistic behavior of a geogrid-reinforced ground subjected to a footing load was discussed using the results of analysis such as stress distribution, propagation of plastic yielding, displacement vector among others.

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Discrete element modelling of geogrids with square and triangular apertures

  • Chen, Cheng;McDowell, Glenn;Rui, Rui
    • Geomechanics and Engineering
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    • v.16 no.5
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    • pp.495-501
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    • 2018
  • Geogrid application that has proved to be an effective and economic method of reinforcing particles, is widely used in geotechnical engineering. The discrete element method (DEM) has been used to investigate the micro mechanics of the geogrid deformation and also the interlocking mechanism that cannot be easily studies in laboratory tests. Two types of realistically shaped geogrid models with square and triangle apertures were developed using parallel bonds in PFC3D. The calibration test simulations have demonstrated that the precisely shaped triangular geogrid model is also able to reproduce the deformation and strength characteristics of geogrids. Moreover, the square and triangular geogrid models were also used in DEM pull-out test simulations with idealized shape particle models for validation. The simulation results have been shown to provide good predictions of pullout force as a function of displacement especially for the initial 30 mm displacement. For the granular material of size 40 mm, both the experimental and DEM results demonstrate that the triangular geogrid of size 75 mm outperforms the square geogrid of size 65 mm. Besides, the simulations have given valuable insight into the interaction between particle and geogrid and also revealed similar deformation behavior of geogrids during pullout. Therefore, the DEM provides a tool which enable to model other possible prototype geogrid and investigate their performance before manufacture.

Model studies of uplift capacity behavior of square plate anchors in geogrid-reinforced sand

  • Keskin, Mehmet S.
    • Geomechanics and Engineering
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    • v.8 no.4
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    • pp.595-613
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    • 2015
  • An experimental investigation into the uplift capacity of horizontal square plate anchors in sand with and without geogrid reinforcement is reported. The parameters investigated are the effect of the depth of the single layer of geogrid, vertical spacing of geogrid layers, number of geogrid layers, length of geogrid layers, the effects of embedment depth, and relative density of sand. A series of three dimensional finite element analyses model was established and confirmed to be effective in capturing the behaviour of plate anchor-reinforced sand by comparing its predictions with experimental results. The results showed that the geogrid reinforcement had a considerable effect on the uplift capacity of horizontal square plate anchors in sand. The improvement in uplift capacity was found to be strongly dependent on the embedment depth and relative density of sand. A satisfactory agreement between the experimental and numerical results on general trend of behaviour and optimum geometry of reinforcement placement is observed. Based on the model test results and the finite element analyses, optimum values of the geogrid parameters for maximum reinforcing effect are discussed and suggested.

Parametric Study on Geogrid-Reinforced Track Substructure

  • Oh, Jeongho
    • International Journal of Railway
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    • v.6 no.2
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    • pp.59-63
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    • 2013
  • The purpose of this paper was to evaluate the effectiveness of geogrid for conventional ballasted track and asphalt concrete underlayment track using PLAXIS finite element program. Geogrid element was modeled at various locations that include subballast/subgrade, subballast/ballast interfaces, middle of the ballast, and one-third depth of the ballast. The results revealed that the effectiveness of geogrid reinforcement appeared to be larger for ballasted track structure compared to asphalt concrete underlayment track. Particularly, in case of installing geogrid at one-third depth of ballast layer in a conventional ballasted track, the most effectiveness of geogrid reinforcement was achieved. The influence of geogrid axial stiffness on track substructure response was not clear to conclude. Further validations using a discrete element method along with experimental investigation are considered as a future study. The effect of asphalt concrete layer modulus was evaluated. The results exhibited that higher layer modulus seems to be effective in controlling displacement and strain of track substructure. However it also yields slightly higher stresses within track substructure. It infers that further validations are required to come up with optimum asphalt concrete mixture design to meet economical and functional criteria.

Durability Assessment of Geogrids by Reduction Factors (감소인자에 의한 지오그리드의 내구성 평가)

  • Jeon, Han Yong;Heo, Dai Young
    • Journal of the Korean Geosynthetics Society
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    • v.3 no.2
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    • pp.31-38
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    • 2004
  • Long-term stability of two type geogrids were evaluated. Membrane drawn type geogrid showed the exponential type tensile property and textile type geogrid showed the rapid increase of tensile property closer toward the break point. Accelerated creep test was done for textile type geogrid but not done for membrane drawn type geogrid because of its thermal property. Creep strain for membrane drawn type geogrid was larger than the ultimate tensile strain by tensile test and reduction factor by creep deformation of textile type geogrid was smaller than that of membrane type geogrid.

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Assessment of Long-Term Stability of Geosynthetic Reinforcement Materials by Reduction Factors (감소인자에 의한 토목합성보강재의 장기안정성 평가)

  • Jeon, Han-Yong;Mok, Mun-Sung;Cho, Seong-Ho;Cha, Dong-Hwan;Kim, Seong-Cheol;Ahn, Ju-Hwan
    • Journal of the Korean Geosynthetics Society
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    • v.4 no.3
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    • pp.11-19
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    • 2005
  • Long-term stability of two type geogrids were evaluated. Membrane drawn type geogrid showed the exponential type tensile property and textile type geogrid showed the rapid increase of tensile property closer toward the break point. Short term accelerated creep test was done for textile type geogrid but done for membrane drawn type geogrid at ambient temperature because of its thermal property. Creep strain for membrane drawn type geogrid was larger than the ultimate tensile strain by tensile test. Reduction factor by creep deformation of textile type geogrid was smaller than that of membrane type geogrid. From this result, it was seen that the textile type geogrid is more stable than membrane type geogrid by creep deformation.

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Bearing Capacity of Geogrid-Reinforced Railroad Ballast (지오그리드로 보강된 철도노반 쇄석기층의 지지력에 관한 연구)

  • 신은철;김두환;이규진;이상조
    • Proceedings of the KSR Conference
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    • pp.367-374
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    • 1999
  • The selection of geogrid types for the use of reinforced rail roadbed is important in the design of railways. Also, the problem of the construction damage on the geogrid during construction is raised by the field engineers. Therefore, laboratory model tests were peformed to investigate the efficiency of the bearing capacity and construction damage. As a result, it was found that the bearing capacity of the rigid geogrid reinforced railroad ballast shows 1.54 times higher than that of the flexible geogrid reinforced case. In addition, there were no noticeable damage during construction.

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Characteristics of Compressive Strength of Geogrid Mixing Reinforced Lightweight Soil (지오그리드 혼합 보강경량토의 강도특성 연구)

  • Kim, Yun-Tae;Kwon, Yong-Kyu;Kim, Hong-Joo
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.383-393
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    • 2006
  • This paper investigates strength characteristics and stress-strain behaviors of geogrid mixing reinforced lightweight soil. The lightweight soil was reinforced with geogrid in order to increase its compressive strength. Test specimens were fabricated by various mixing conditions including cement content, initial water content, air content and geogrid layer and then unconfined compression tests were carried out. From the experimental results, it was found that unconfined compressive strength as well as stress-strain behavior of lightweight soil were strongly influenced by mixing conditions. The more cement content that is added to the mixture, the greater its unconfined compressive strength. However, the more initial water content or the more air foam content, the less its unconfined compressive strength. It was observed that the strength of geogrid reinforced lightweight soil was increased due to reinforcing effect by the geogrid for most cases except cement content less than 20%. In reinforced lightweight soil, secant modulus $(E_{50})$ was increased as the strength increased due to the inclusion of geogrid.

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Testing and Numerical Analysis Techniques for Pull-out Resistance Characteristics of the Extensible Geogrid (신장성 지오그리드 보강재의 인발저항특성 평가를 위한 시험 및 수치해석 기법)

  • 이성혁;고태훈;이진욱;황선근
    • Journal of the Korean Society for Railway
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    • v.5 no.2
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    • pp.93-103
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    • 2002
  • Reinforced earth structure has been regarded as general structure in order to achieve efficient land utilization as well as securing safety in railway service lines in other countries, but there are no construction actual results in Korea. In this study, the soil-geogrid interaction mechanism was investigated experimentally and numerical analysis was performed to predict Pull-out behaviour of geogrid embedded in reinforced earth body. This experimental data and analysis result can not contribute to understand the soil-geogrid interaction mechanism at soil-geogrid interface but also be used in design practice of the railway reinforced earth structures.