• Journal of the Korean Geosynthetics Society
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• v.15 no.3
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• pp.39-47
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• 2016

In order to prevent leakage of leachate in offshore landfill, hydraulic barrier is indispensable. In the case of rubble mound revetment at offshore landfill, HDPE sheet in slope should be installed. In this study, seepage analysis were performed to evaluate seepage and flow in the seabed and revetment according to extended length of HDPE sheet by using SEEP/W. Results show that, in the case of low permeability layer is distributed where extended length of HDPE sheet was more than 1m, seepage flux in seabed and revetment was greatly reduced. In order to prevent seepage in seabed and revetment in the case of sand layer of high permeability is existed above low permeable layer, extended length of HDPE sheet and impermeable improvement width of permeable layer should be more than 1m at seabed.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.285-298
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• 2003

Shear properies of geosynthetic/geosynthetic and geosynthetic/soil interfaces which are widely met in landfill sites were evaluated from the inclined board tests. The inclined board testing apparatus is known to reproduce the shear behavior on the low normal stress most accurately. In this study, the friction angle of each interface was estimated and the tensile force mobilized at the geosynthetic was measured as well. The test results showed that the friction angle of each interface and the tensile force of the geosynthetics depended on the amount of normal stress, the type of the geosynthetics used, and the combinations of geosynthetics and soils. In addition, the sand/geotextile/geomembrane interface system was simulated in this study, and it was observed that the tensile force developed at the geomembrane decreased due to the protection effect of the geotextile located above the geomembrane. The test results of this research was compared with those of direct shear tests published, too. Finally, by comparing the measured tensile force of the geosynthetics when the initial displacement of the box occurs, when the slope is called as the critical slope, with suggested analytic solution, the accuracy of analytic solution and the applicability to design were identified.

• Journal of the Korean Geotechnical Society
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• v.21 no.4
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• pp.115-122
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• 2005

In this paper, a new method composed of discrete element method and genetic algorithm has been introduced to estimate the safety factor and search critical slip surface on slope stability analysis. In case of estimating the safety factor, conventional methods of slope analysis based on the limit equilibrium do not satisfy the overall equilibrium condition; they must make assumptions regarding the inclination and location of the interstice forces. An alternative slope analysis method based on the discrete element method, which can consider the compatibility condition between force and displacement, is presented. Real-coded genetic algorithm is applied to the search for the minimum factor of safety in proposed analysis method. This search method is shown to be more robust than simple optimization routines, which are apt to find local minimum. Examples are also shown to demonstrate the applicability of the proposed method.

• 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.

• Journal of the Korean Geosynthetics Society
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• v.9 no.1
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• pp.39-46
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• 2010

Recently, the effective use of closed waste landfill nearby urban areas has been demanded, because of the lack of the usable land. However, the reuse of closed landfill is needed an adequate stabilization of liner system. But most of these places are consisted of steep slope and hence it is necessary to use the geosynthetics liners in there. Liner system of waste landfills is an important facility which prevents leachate outgoing from the landfills and also groundwater infiltrating from surroundings into the landfills. During the waste disposal stage, differential settlement and tensile stress of the geosynthetic materials could occur due to impact load of trucks and dozers, waste loads and weak foundation soils. In this study, the tensile strength and tracer test were performed to evaluate the stability of geomembrane liner systems. Based on the tensile strength test result of in-situ geomembrane sample, the yield tensile strength maintain the suitable strength by specification and current law. However, according to the tracer test, the damage of geomembrane liner was detected on sanitary landfill section.

• Journal of the Korean Geosynthetics Society
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• v.12 no.4
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• pp.67-76
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• 2013

Landfill require special care due to the dangers of nearby surface water and underground water pollution caused by leakage of leachate. The leachate does not leak due to the installation of the geomembrane but sharp wastes or landfill equipment can damage the geomembrane and therefore a means of protecting the geomembrane is required. In Korea, in accordance with the waste control act being modified in 1999, protecting the geosynthetics liner on top of the slope of landfill and installing a drainage layer to fluently drain leachate became mandatory, and technologies are being researched to both protect the geomembrane and quickly drain leachate simultaneously. Therefore, this research has its purpose in studying the drainage functions of leachate and protection functions of the geomembrane in order to examine the application possibilities of Geo-Multicell-Composite (GMC) as a Leachate Collection Removal and Protection System (LCRPs) at the slope on top of the geomembrane of landfill by observing methods of inserting filler with high-quality water permeability at the drainage net. GMC's horizontal permeability coefficient is $8.0{\times}10^{-4}m^2/s$ to legal standards satisfeid. Also crash gravel used as filler respected by vertical permeability is 5.0 cm/s, embroidering puncture strength 140.2 kgf. A result of storm drain using artificial rain in GMC model facility, maxinum flow rate of 1,120 L/hr even spray without surface runoff was about 92~97% penetration. Further study, instead of crash gravel used as a filler, such as using recycled aggregate utilization increases and the resulting construction cost is expected to savings.

• Korean Journal of Environment and Ecology
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• v.29 no.3
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• pp.431-440
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• 2015

This study investigated the correlation between the trees planted on the slope of the first landfill where the landfill was completed and the soil environment. 69 plots (($7{\sim}20m{\times}5{\sim}20m$) were planted with 26 kinds of major trees in the first landfill slopes for vegetation survey. The survey was conducted from 2007 to 2009. Soil analysis from 2007 to 2008 was made on the basis of the injured index and the indicator species were selected. Depending on the rate of growth of the indicator species, seven survey locations were selected for soil sample analysis. 10 tree species appeared to adapt to the landfill environment. Among them, the coniferous trees were Pinus thunbergii (Seedling) and Juniperus chinensis and the deciduous trees were Quercus aliena, Salix preudo-lasiogyne, Castanea crenata (Seedling), Prunus armeniaca var. ansu, Quercus acutissima, Chionanthus retusus, Liriodendron tulipifera (Seedling) and Celtis sinensis. 8 species of trees did not adapt well to the landfill environment. Among them, two kinds were coniferous, the other six kinds were deciduous. In addition, judgment on the other 8 species of trees as to whether they adapted well or not was postponed. The species for which judgment was postponed included one coniferous tree and seven deciduous trees. Indicator species of injured index was the species that have more than 25 % of the defect. The soil was collected from where Catalpa ovata, Sophora japonica, Albizzia julibrissin and Acer palmatum were planted for analysis. According to the soil analysis, the soil pH showed that the soil was alkaline. Regarding the three phases of the soil, most sample soil showed 60 % for the solid phase or 55 % for the solid phase but with less than 10 % of gas phase. The organic matter content was found to be 0.14 to 2.52 %.

• Journal of the Korean earth science society
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• v.23 no.3
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• pp.270-279
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• 2002

The concentrations of major greenhouse pollutants which include $CO_2$ and $CH_4$ were determined from the outlet of 42 ventpipes in Nan-Ji-Do area of Seoul during September/October of 2000. Using these data, the concentration distribution of major greenhouse gases was checked and compared. The mean concentrations of $CO_2$ and $CH_4$, computed using the data sets collected from 42 ventpipes, were 27.8 and 50.9%, respectively. Because the concentration levels were different not only between plain and slope areas of each sector but also between chemicals, evaluation of the data sets was made after dividing them separately into four data groups. The results of our analysis clearly indicate that their distribution is rather homogeneous than those of minor constituents of landfill ventilated gases (e.g., Hg).

• Journal of the Korean Geotechnical Society
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• v.21 no.6
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• pp.147-154
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• 2005

This study deals with the calibration of low-frequency water content reflectometer for measuring the volumetric water content of soils in landfill final cover layer, and the validity of calibrations was evaluated by electrical conductivity and index properties of the soils. Linear calibrations concerning volumetric water content to WCR period provided good agreement with the data. Analysis of the calibration data indicates that the slope of the calibration decreases as the electrical conductivity of the soil increases. Lower slopes correspond to soils with greater clay content, organic content, liquid limit, and plasticity index, which typically have higher electrical conductivity. It could be well explained that WCR can operate in a lower frequency range.

• Journal of the Korean Geosynthetics Society
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• v.2 no.2
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• pp.25-31
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• 2003

Most recently, environmental problems arise from management waste tires by increasing number of automobiles. Waste tires are not compressible and not easy for degradation in landfill. Even if it were landfill, it is difficult to treat. Total amount of waste tires is about 20 million per year and the collection is 68.6% in this country. Structure of slope stability using waste tire blocks filled with concrete increases durability, reduce construction period, and it can be utilized as an example. Therefore, it reduces the volume of waste and recycles waste. Also, it prevents the air pollution due to the incineration and creates economic value.