• Journal of the Korean Geotechnical Society
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• v.23 no.10
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• pp.65-72
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• 2007

Large-scale direct shear tests were conducted in order to investigate both the shear strength of soil itself and the friction behavior at the interface of soil/geosynthetics in respect of efficiency in this study. Sand, crushed stone and three types of geotextile (i.e. one woven geotextile and two nonwoven geotextiles) were used in the experimental program. The considered interfaces for the evaluation of interface shear strength in this study included sand/sand, crushed stone/crushed stone, sand/woven geotextile, crushed stone/woven geotextile, crushed stone/nonwoven geotextile-A and crushed stone/nonwoven geotextile-B. The results showed that the efficiency of 84% was obtained at the interface of sand/woven geotextile compared with the shear strength of sand itself (i.e. sand/sand interface). The efficiencies of 74%, 83% and 72% were obtained at the interface of crushed stone/nonwoven geotextile-A, crushed stone/nonwoven geotextile-B and crushed stone/woven geotextile, respectively compared with the shear strength of crushed stone itself (i.e. crushed stone/crushed stone interface).

• Geotechnical Engineering
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• v.14 no.4
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• pp.61-76
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• 1998

Various kinds of reinforced soil methods have been developed by many researchers or companies for their economic merits mainly. These methods have generally used sandy soils which have high permeability as embanking or backfill material. That is because, if poor embanking materials, especially like a clayey soil which has very low permeability, are used in a reinforced soil embanking, and if excessive pore water pressure is produced by external factors, the friction resistance between reinforcing members and Boils decrease, as a result possible damage or collapse of the body of a reinforced embankment. In fact, clayey Boils can also be used as a embanking materials with reinforcement which has high permeable capacity, and are expected to be able to dissipate the excess pore water pressure effectively. In this study reinforcing effects have been examined through a serries of direct shear tests in which clayey soils are reinforced with nonwoven geotextiles of which permeability is very high and tensile strength is relatively weaker than geogrids which are usually used in reinforced soil wall. Even though such nonwoven geotextile are used as reinforcement of high saturated clayey soils. the test results show the possibility that nonwoven geoteztiles could be used as a reinforcement for reinforced soil walls effectively.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.453-460
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• 2004

To prevent penetration of rainwater into the landfill site is the main purpose of the final cover in landfill sites. Conventional designs of landfill covers uses geotextiles such as geomembrane and GCL, and clay liners to lower the permeability of final covers of landfill sites. However, differential settlement and the variation of temperature in landfill sites cause the development of cracks or structural damage inside the final cover and it is also difficult to obtain clay - the main material of the compacted clay liner in Korea. Thus the former final cover system that suggests geomembrane and GCL or compacted clay liner has several limitations. Therefore, an alternative method is necessary and one of them is the application of SRSL(self-Recovering Sustainable Liner) material. SRSL is two different layers consist of individual materials that react with each other and form precipitates, and with this process lowers the permeability of the landfill final cover. SRSL generally is made up of two layers, so that when a internal crack occurs the reactants of the two layers migrate towards the crack and heal it by forming another liner. In this study the applicability of SRSL material for landfill final cover was examined by performing; (1) jar test to verify the formation of precipitate in the mixture of each reactants, (2) falling head test considering the field stress in order to confirm the decrease of permeability or prove that the hydraulic condctivity is lower than the regulations, (3) compression tests to judge weather if the strength satisfies the restricts for landfills, (4) freeze/thaw test to check the applicability of SRSL for domestic climate. In addition, the application of waste materials in the environmental and economical aspect was inspected, and finally the possibility of secondary contamination due to the waste materials was examined by performing elution tests.

• Journal of the Korean Geosynthetics Society
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• v.8 no.2
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• pp.47-54
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• 2009

The ballast track, the most common type of conventional railroad track in Korea, is deteriorated by abrasion of ballast, it's penetration into roadbed, and rugged surface of roadbed caused by cyclic loading of train. Persistent occurrence of those phenomena lead to insufficient drain capacity, one of major factors in track design, and it increases pore water pressure and decreases of shear strength under rainfall condition leading to unstable roadbed. In this study, cylindrical model tests are executed for 3 types of geotextile applying cyclic loading in order to observe the characteristics of displacement and bearing capacity of geotextile, and undrained condition has been applied for 0 day, 3 days and 7 days to each geotextiles. The results showed that there was about 1% difference at the final displacement rates between reinforced soils and nature soils and the displacement of the ground surface increases along with the degrees of the saturation. And in case that water contents exceeds the threshold, it is also apparent that weight and tensile strength of geotextile influences displacement of the ground surface. And the larger weight of geotextile is, the smaller plastic displacement. It is evaluated that non-woven fabric comes into effect on reducing the bearing capacity but, the weight of geotextile has little influence on it.

• Journal of the Korean Geosynthetics Society
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• v.21 no.4
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• pp.69-78
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• 2022

Geotextile tubes are widely used to prevent erosion in coastal areas and to replace the backfill for shore slopes in the reclamation of land using dredged soil. In this study, The triaxial confining pressures were chosen as 10kPa, 50kPa, or 100kPa for the specimens reinforced with geotextile considering the condition in the site. The strain behavior under various compressive stresses was then identified. At strains 0% to 7%, the stress-strain behavior was the same due to the effect of initial strain hardening, in which the force was exerted according to the relaxation of the geotextile regardless of the confining pressure (≤100kPa). At strains of 7% or more, the specimen with the small confining pressure had smaller deformation under load, which increases the tensile resistance provided by the reinforcing geotextile. Brittle fracture was then observed due to strain softening and the deviator stress abruptly decreased. This is different from the phenomenon in which the shear strength increases as the confining pressure increases in general triaxial compression tests. In the geoxtile-confined tests, geotextiles are primarily subjected to tensile displacement. Thereafter, the modulus of elasticity increases rapidly, which exhibits the elastic behavior of the geotextile.