• Journal of the Korean Geosynthetics Society
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• v.3 no.2
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• pp.23-29
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• 2004

One of the most important concern in the design of barrier layer in to protect the water through the landfill. The barrier layer consists of a single compacted clay liner(CCL) or a composite liner with high density polyethylene(HDPE). The construction of barrier layer at the edge of cover system usually has some problems because of steep slope in the landfill. In this study the authors evaluate the geosynthetic clay liner(GCL) as a barrier layer at the edge of the final cover system in landfill. The GCLs were simulated the stability of slope, the HELP(Hydrologic Evaluation of Landfill Performance) and the durability of environmental situation. As the results, the GCL has more stable than the CCL. Therefore, the authors suggest that the GCL in good for the barrier layer of the final cover system in the landfill.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.295-304
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• 2010

Performance of a landfill liner is evaluated based on leakage rate and mass flux. In this study, the recently utilized double composite liner system, which consists of a geomembrane (GM), a geosynthetic clay liner (GCL), a GM, and a compacted clay layer (61 or 91.5 cm) is compared with other popular composite liners including the single GCL system, the Subtitle D liner system, and the Wisconsin NR500 liner system. The leakage rate through circular and long defects in the GM of the landfill liners is analyzed using numerical models. For the mass flux criterion, the analyses of inorganic contaminant transport through defects in the GM component of liner systems and diffusion of organic compounds through intact landfill liners are conducted using three- and one-dimensional numerical models, respectively. Cadmium and toluene are used in the analyses as a typical inorganic and organic substance, respectively, which will be chemical species encountered during landfill operation. The comparison shows that the double composite liner systems are superior to the other liner systems according to the performance-based evaluation.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.137-146
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• 2002

Geomembrane, compacted clay liner, and geosynthetic clay liner (GCL) are widely used to prevent leachate from leaking to adjacent geo-environment at a municipal solid waste (MSW) landfill. Interface shear strength between GCL and geomembrane installed at a landfill side slope is important properties for the safe design of side liner or final cover systems. The interface shear strength between two geosynthetics was estimated by a large direct shear test in this study. The shear strength was evaluated by the Mohr-Coulomb failure criterion. The effects of normal stress, hydration or dry condition, and a hydration method were investigated. The test results show that the interface shear strength and shear behavior varied depending up on the level of normal stress, the type of geosynthetic combinations, and a hydration method. When GCLs were sheared after being hydrated under 6kPa loading, the results were consistent with those published by other researchers. Summaries of friction angles, normal stress and hydration condition is presented. These friction angles could be used as a reference value at a site where similar geosynthetics are installed.

• Proceedings of the Korean Fiber Society Conference
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• 1998.10a
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• pp.352-355
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• 1998

토목섬유제품 중에서 차수재조 널리 사용되는 지오멤브레인은 1$\times$$10^{-12}$의 낮은 투수계수를 갖고 있지만 시공전후 찢어지거나 구멍이 뚫리게 되면 침출수의 유출이 발생하여 환경오염을 일으키게 된다. 이를 보완하기 위해 친수성과 팽윤성이 큰 벤토나이트 물질을 이용한 Geosynthetic Clay Liner(GCL) 복합재료가 개발되었다. GCL은 지오텍스타일이나 지오멤브레인사이에 벤토나이트를 충진시키고, 접착제 또는 니들펀칭(needle-punching)이나 스티칭(stitching)과 같은 기계적인 방법으로 결합한 복합재료이다. (중략)

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.621-628
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• 2003

To prevent the percolation of leachate through the bottom of waste landfills, the liner system of various layers, such as compacted clay, geomembrane, geonet, geotextiles, and geocomposite is designed. Since the friction angle between a geomembrane and other geosynthetics is usually lower than that of the soil alone, the interfaces between soil and geosynthetic or geosynthetic-geosynthetic may become a possible plane of weakness, which leads to potential instability of the system under load of waste at side slopes. In this study, large triaxial tests are carried out with samples of remoulded wastes and direct shear interface friction tests are carried out to understand the frictional properties of geosynthetic-geosynthetic interfaces, which are required for analyzing the safety of side-slope liner systems.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.245-254
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• 2009

Efficiency of landfill liners system is usually evaluated based on leakage rate and mass flux. In this study, composite liner systems including the GCL(geosynthetic clay liner) composite liner, the Subtitle D liner, the Wisconsin NR500 liner, and the recently utilized double composite liner, which is a combination of the GCL composite liner and Subtitle D-type liner, have been examined. The leakage rate through circular and long defects in the geomembrane (GM) of the liner system was analyzed with the aids of analytical and numerical methods. For the mass flux criterion, contaminant transport through defects in the GM of landfill liners can be evaluated based on the calculated leakage rates. The diffusion rate of volatile organic compounds through intact landfill liners was evaluated by performing a one-dimensional numerical model. Cadmium and toluene were adoptted in the analyses as typical inorganic and organic substances, respectively, which will be chemical species encountered during landfill operation. The performance-based evaluation indicates that the double composite liner systems are superior to the other types of liner.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.59-62
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• 2004

Hydraulic conductivity tests were conducted on a geosynthetic clay liner (GCL) for more than 2.5 yr using inorganic salt solutions to evaluate how the long-term hydraulic conductivity is affected by cation concentration and valence. Only small changes (i.e., $\leq$ 2X) in hydraulic conductivity (K) occurred during the test duration when the permeant solution was deionized (DI) water or 100 mM KCl and NaCl solutions. For weak CaCl$_2$ solutions ($\leq$ 20 mM), the hydraulic conductivities initially (< 0.2 yr) were comparable to the hydraulic conductivity obtained with DI water, but gradually increased by a factor of 2 to 13 over a period of nearly 2 yr. In contrast, the GCL permeated with strong CaCl$_2$ solutions ($\geq$ 50 mM) reached equilibrium nearly immediately, with a hydraulic conductivity approximately 2 orders of magnitude higher than the hydraulic conductivity to DI water.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.395-398
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• 2003

Geosynthetic Clay Liners(GCLs) have been widely used as hydraulic barrier in landfills and remediation projects of contaminated sites. The aim of this research is to modify GCLs for effective removal of contaminants. We perform the free swell test, hydraulic conductivity test, and contaminants (TCE, hexavalent chromium, and nitrate) removal test on the bentonite-ZVI mixture with various ZVI content. As the ZVI content increased, contaminants removal efficiencies and swell volume increased, and hydraulic conductivity decreased.

• Journal of the Korean Geosynthetics Society
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• v.5 no.4
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• pp.49-58
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• 2006

Recently, geosynthetic clay liners (GCLs) have increasingly been used to replace compacted clay liners (CCLs) in composite liner systems. Since the introduction of GCLs to waste containment facilities, one of the major concerns about their use has been the hydraulic equivalency to CCLs as required by regulations. Laboratory test results and more recently field observations show that the thickness, or mass per unit area, of hydrated bentonite in a GCL can decrease under normal stress, especially around zones of stress concentration or nonuniform stresses, such as a rock or roughness in the subgrade, a leachate sump, or wrinkles in an overlying geomembrane. This paper presents field case histories that confirm the laboratory observations of bentonite migration and the effect of bentonite migration on hydraulic equivalency and contaminant transport through a GCL.

• Journal of Soil and Groundwater Environment
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• v.7 no.1
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• pp.33-40
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• 2002

The study was performed to evaluate the effect of landfill leachate on the hydraulic conductivity of Geosynthetic Clay Liner (GCL) with two types of leachate. GCL used in waste landfills have a significant ability as a barrier material, however, they also have a potential danger when exposed to some organic and inorganic leachate as well as humic materials. In this study, swelling tests and hydraulic conductivity tests were performed to evaluate the effect of humic materials and landfill leachate on the hydraulic characteristics of the GCL. The result of swelling tests showed that the amount of humic materials and high electronic conductivity caused a decrease of the swelling of bentonite. This is expected to increase the hydraulic conductivity of GCL. The increasing of hydraulic conductivity observed for GCL permeated with 0-leachate was significantly higher than that of Y-leachate. This result shows that humic materials are obviously affecting with the increasing of hydraulic conductivity of GCL.