Authors: Han Yong Jeon, Y.H. Lee, Jung Min Seo, Beong Bok Hwang, H.S. Koo
Abstract: This paper is concerned with the performance of geo-textile (GT) against chemical
condition. GT is generally adopted for the upper part of geo-membrane (GM) for waste landfills and
thus it is very important to consider the performance of GT against certain chemical environments
until landfill is completed. In this study, PVA geo-textile/HDPE geo-membrane was prepared to
investigate the waste landfill related properties in terms of long-term performance against chemical
conditions imposed. GT composites of PVA GT/HDPE GM, PVA GT and HDPE GM were produced
in thermal bonding process. Polyester and polypropylene GT were also manufactured in needle
punching process. The experiments have been conducted under a modified version of EPA 9090 test
method which is very similar to the method of evaluating chemical resistance of flexible membrane
liner by the US Environmental Protection Agency (EPA). In this testing method, samples immersed
in chemical of different solutions up to 150 days at 30 day interval were obtained to find tensile
strength holding rate and chemical resistance. The analysis in this paper is focused to evaluate the
effect of different pH conditions and temperature environments on geo-synthetics weights strength
retention. It was concluded from the experiments that tensile strength of GT composites against
leachate were reduced by 10 to 20% in both polypropylene and polyester non-woven GT. The
reduction was more significant at temperatures of 50 °C than that at 25 °C. The experiments
conducted in this study demonstrated that PVA GT is excellent in terms of chemical resistance.
988
Authors: Jung Min Seo, Han Yong Jeon, Beong Bok Hwang, Y.H. Lee, H.S. Koo
Abstract: This paper is concerned with the long-term performance of geo-textile (GT) composites in
terms of creep deformation and frictional properties. Composites of PVA GT and HDPE GM were
made to investigate the advanced properties of long-term performance related to waste landfill
applications. The same experiments were also performed for typical polypropylene and polyester GT
and compared to PVA GT/HDPE GM composites. The main purpose of this study is to develop high
performance GT composites with GM by using PVA GT which is capable of improving frictional
property and thus enhances long-term performance of GT composites. In the present experiments, GT
composites of PVA GT/HDPE GM, PVA GT of 600, 1000, 1500, 2000g/m2 and HDPE GM were
prepared in thermal bonding process. Polyester and polypropylene GT were also made in needle
punching process. The creep deformation of GT composites was measured and evaluated in
accordance with ASTM D5262. Frictional characteristics of GT composites tested in this study were
conducted with compact direct shear apparatus in accordance with ASTM D5321. It was concluded
from the present experimental study that friction coefficient of GT composites is relatively large
compared with those of polyester and polypropylene non-woven GT as long as the friction media has
similar size to the particles of domestic standard earth. In the event that 20% of the maximum tensile
strength was added to polypropylene and polyester non-woven geo-textiles, creep deformation
reached to 10% or higher, making it even impossible to find reduction factor.
1043
Abstract: The primary objective of this paper is to study the seepage behavior of the cutoff wall and the working mechanism of the composite geo-membrane applied in the second stage cofferdam of the Three Gorges Dam. The mixture proportion of the plastic concrete applied in the cutoff wall is researched and a recommended proportion is put forward. The difference between the composite geo-membrane and single geo-membrane concerning mechanical strength and permeability is detected and reasons which lead to the difference are found. The test results indicate that the mechanical characters of the composite geo-membrane have been improved remarkably. It is demonstrated that the deformation ratio plays an important role in terms of the permeability by bursting test. The behavior of the composite geo-membrane and the effect of the composite materials in different work-stage are studied and the influence of the elasticity of the composite materials on the practical application of the composite geo-membrane is analyzed. It is found that the strength is not just the superposition of the strength of composite materials and membrane.
146
Authors: Xiao Song Tang, Ying Ren Zheng, Yong Fu Wang
Abstract: With the conduction of west development in China, the constructions of airports in the southwest mountainous areas are being carried out rapidly. Due to the various exteriors limitations, the embankment engineering in airports often exist some problems such as large height and slope ratio. So the stability of high embankment engineering is very essential to the construction and operation of airport. The cost of geo-grid material is very low and the construction is convenient. The embedding and occlusion of soil mass can be realized through its unique grid structure. The practical engineering shows that the stability of high embankment engineering can be solved through laying geo-grid in the filling soil. At the same time, FEM strength reduction can take the interaction between the components of geo-grid and soil into full consideration. As a strict mechanic method, FEM strength reduction can be reasonably and reliably adopted in the stability analysis, design and calculation of reinforced body with geo-grid.
1879
Authors: Jia Horng Lin, Chen Hung Huang, Chao Yin Hsiao, Kuo Cheng Tai, Jin Mao Chen, Ching Wen Lou
Abstract: In this study, carbon fiber/ polypropylene (PP) complex braiding yarn, with its different breaking strength, was prepared. It was designed by braiding polypropylene (PP) wrapped yarn and carbon fiber core yarn using eight and sixteen spindles braiding machines, with change of take-up gear number. Environmental factors, such as pH, temperature and time, were also changed to produce geo-grids with high strength, high modulus and better weather resistance. In order to make stable structure for complex braiding yarn, the heat treatment was also considered. Finally, geo-grids braiding by optimal treatment parameters were cut into single rib and junction specimens for tensile test.
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