• Journal of the Korean GEO-environmental Society
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• v.2 no.4
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• pp.39-50
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• 2001

In this study, in order to investigate the effects of reinforcement length and vertical spacing on the factor of safety, the road embankment reinforced by geogrid was analyzed using RSS(Reinforced Slope Stability) program based on limit equilibrium analysis. The result by computer analysis showed that the factor of safety for reinforced slope increased with increasing length of reinforcement and with decreasing vertical spacing of reinforcement up to certain limit. Also, numerical analysis by FLAC was performed on reinforced slope to evaluate the horizontal displacement, horizontal stress, and distribution of tensile forces of reinforcements in the cases of several reinforcement length. The results of analysis showed that the critical failure mode was toe failure or slope failure and the effect by the additional reinforcement length on the slope stability was negligible under stabilized condition.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.11c
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• pp.1-10
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• 1999

In the present study, laboratory pull-out tests with various geogrid shapes are carried out to investigate behavior characteristics of the geogrid. Also, an interface pullout formula is proposed for predicting and interpreting pullout test result. The analytical model is based on the assumption that the reinforcement is linear elastic during the pullout test. And then, maximum pullout force, frictional resistance and active length for each of the grid density ratio are predicted based on the interface pullout formula. The predicted results were compared with those of pullout tests, and showed in general good agreements.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.813-820
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• 2003

The shear friction tests using large direct shear test units were performed to evaluate the friction properties of fiber-mixed soil. The used materials and test conditions were flowing. Soils : SM and ML; mixing fibers : three types of polypropylene fibers(net type 38mm and 60mm, and line type 60mm), reinforcement : geogrid; mixing ratio：0.2% and 0.3%; degree of compaction : 85% and 95%. In the test results, the reinforcing effect of fiber mixed soil was confirmed.

• Proceedings of the KSR Conference
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• 2000.05a
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• pp.407-414
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• 2000

Recently the geogrids are being used in some large projects such as Inchon International Airport construction, highway construction, and Korean High-Speed Railway construction with not only the merit of simple construction but also reinforcing efficiency for the soft ground. Main function of roadbed is to provide a stable foundation in terms of bearing capacity and settlement for the subballast and ballsat layers. Differential settlement of the railroad should be avoided. The cyclic laboratory model tests were performed to investigate the settlement behavior of geogrid reinforced railroadbed. The ratio of settlement of roadbed under cyclic loading with three layers of geogrid reinforced is less than 1/2 of the roadbed thickness without reinforcement.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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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.

• Geotechnical Engineering
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• v.12 no.6
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• pp.21-36
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• 1996

The stress transfer mechanism between soil and grid reinforcements involves two basic mechanism : frictional soil resistance and passive soil resistance. However the mechanism of the passive soil resistance is very complex to understand. To study the failure mechanism of ribbed reinforcement, the direct shear tests which are dominated by passive soil resistance are analyzed by using the finite element method. The finite element method is used to examine the effects of ribs on this passive soil resistance development and the met hanism of failure. The calculated behavior of the ribbed reinforcement is compared with the measured behavi or. Comparisons between the measured and the simulated strain pat terns, failure modes and load displacement relationship are presented. The behavior of the ribbed reinforcements in a cohesive soil is predicted on the basis of a good agreement between the measured and the Predicted behavior of the Ottawa sand.

• Journal of the Korean Geosynthetics Society
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• v.16 no.1
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• pp.53-61
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• 2017

Seabed settlement and erosion sometimes occurr when a artificial reef is installed in soft seabed. Therefore, this study carried out CBR test and water tank settlement test to investigate settlement behavior of artificial reef according to reinforcement characteristics such as reinforced types and reinforced area. Soil types of ground are sand, silt and clay deposits. Three reinforced types were prepared: unreinforced, geogrid and hybrid bamboo mat(HBM) with different reinforced area. Laboratory test results indicated that reinforced artificial reef improved bearing capacity of ground and reduced settlement as reinforced area increased. Especially, reinforced HBM provided more bearing capacity and less settlement than reinforced geogrid.

• Geomechanics and Engineering
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• v.32 no.6
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• pp.653-671
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• 2023

In practice, the interference influence caused by adjacent footings of structures on geo-reinforced loose soil has a considerable impact on their behavior. Thus, the goal of this study is to evaluate the behavior of two strip footings in close proximity on both geocell and geogrid reinforced soil with different reinforcement layers. Geocell was made from geogrid material used to compare the performance of cellular and planar reinforcement on the bearing pressure of twin footings. Extensive experimental tests have been performed to attain the optimum embedment depth and vertical distance between reinforcement layers. Particle image velocimetry (PIV) analysis has been conducted to monitor the deformation, tilting and movement of soil particles beneath and between twin footings. Results of tests and PIV technique were verified using finite element modeling (FEM) and the results of both PIV and FEM were used to utilize failure mechanisms and influenced shear strain around the loading region. The results show that the performance of twin footings on geocell-reinforced sand at allowable and ultimate settlement ranges are almost 4% and 25% greater than the same twin footings on the same geogrid-reinforced sand, respectively. By increasing the distance between twin footings, soil particle displacements become smaller than the settlement of the foundations.

• Journal of the Korean Geotechnical Society
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• v.15 no.5
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• pp.171-191
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• 1999

The final aim of this research is to systematize the reinforced-earth wall system using the geosynthetic composite reinforcement in the weathered granite backfill soils having relatively large amount of fines. As a staged endeavour to accomplish this purpose, laboratory pull-out tests and finite element modeling are carried out in the present study focusing on the analyses of friction characteristics associated with interaction behaviors of the geosynthetic composite reinforcement composed of geogrid with a superior function in tensile resistance and geotextile with sufficient drainage effects. In addition, drainage effects of the geotextile below geogrid are examined based on the analysis of finite difference numerical modeling. From the present investigation, it is concluded that the geosynthetic composite reinforcement in the weathered granite backfills may possibly be used to achieve effects on both a reduction of deformations and an increase of the tensile resistance, together with drainage effects resulting from the geotextile.

• Journal of the Korean GEO-environmental Society
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• v.10 no.4
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• pp.41-48
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• 2009

A flexible pipe was buried 10cm below the ground formed with standard sand to observe changes in the shape of the pipe according to the behavior of ground at each relative density. Changes in the shape of the pipe in each ground were observed to examine the behavior of the pipe under the state of reinforced ground after installing geogrid under the pipe. Ground reinforced using geogrid formed tensile force on the reinforcement material with increase in the vertical load and showed reduction in settlement under identical vertical load with existence of reinforcement. Distributions of ground deformation of 100% relative density and 70% relative density had clear difference. Reinforced ground with 70% density converged to the ground reaction of final settlement of non-reinforced ground with 100% density at final settlement of 100 mm. Because the shape of lower part strain of the buried pipe is similar to that of un-reinforced ground with relative density of 100%, reinforcement effect by geogrid in soft ground can be anticipated.