• Advanced Composite Materials
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• v.17 no.3
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• pp.247-258
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• 2008

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. We also develop high performance GT composites with GM by using PVA GT, which is capable of improving the frictional properties and thus enhances long-term performance of GT composites. Experimental study reveals that the 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 addition, the geo-composites bonded with geo-grid by a chemical process were investigated experimentally in terms of strain evaluation and creep response values. Geo-grid plays an important role as a reinforcing material. Three kinds of geo-grid were prepared as strong yarn polyester and they were woven type, non-woven type, and wrap knitted type. The sample geo-grids were then coated with PVC. The rib tensile strength tests were conducted to evaluate geo-grid products in terms of tensile strength with regard to single rib. The test was performed according to GRI-GGI. It was concluded again from the experiments that the tensile and creep strains of the geo-grid showed such stable values that the geo-grid prepared in this study could protect geo-textile partially in practical structures.

• Journal of the Korean Geotechnical Society
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• v.23 no.11
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• pp.77-85
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• 2007

This paper investigates the mechanical characteristics of composite geo-material which was developed to reuse both dredged soils and bottom ash. The composite geo-material used in this experiment consists of dredged soil taken from the construction site of Busan New Port, cement, air foam and bottom ash. Bottom ash is a by-product generated at the Samcheonpo thermal power plant. Several series of laboratory tests were performed to investigate behavior characteristics of composite gee-material, in particular the reinforcing effect by mixing bottom ash. The experimental results of composite geo-material indicated that the stress-strain relationship and the unconfined compressive strength are strongly influenced by mixing conditions. Especially it was observed that the compressive strength of composite geo-material increased with an increase in bottom ash content due to reinforcing effect by the bottom ash. Compressive strength of composite geo-material increased with the increase in curing time. The 28-day strength of composite geo-material is $1.7{\sim}1.8$ times higher than the 7-day strength. The moist unit weight strongly depended on air-foam content as well as bottom ash content added to the composite goo-material. In composite geo-material, secant modulus ($E_{50}$) also increased as its compressive strength increased due to the inclusion of bottom ash.

• The Journal of Engineering Geology
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• v.16 no.3 s.49
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• pp.227-233
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• 2006

Bedrock is inhomogeneous for its genetically diverse origins and geological conditions when it forms, and especially, conglomerates and core-stones are one of these typical composite geo-materials composed of weak matrixes and strong pebbles. Mechanical properties of these composite bedrocks, like a conglomerate, generally vary depending on the mechanical properties and distributions of pebbles and the matrix. Therefore, regarding the consequence of understanding mechanical property of bedrocks in the designing slopes, tunnels, and other engineering facilities, empirical rock classification methods generally applied in the mechanical property modeling may not be suitable and rather, we may need some other classification methods, or tests more specific for these inhomogeneous composite bedrocks. This study includes a series of analyses to see elastic behaviors and modulus of composite geo-materials using homogenization theory. Forty nine case models were made for the elastic analysis with considering 5 factors such as gravel content, gravel size, strength of matrix, sorting and dip angle. The results analyzed are applicable to calculate elastic modulus of composite geo-materials as conglomerates and core-stones.

• Journal of the Korean GEO-environmental Society
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• v.14 no.7
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• pp.13-18
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• 2013

As a new foundation treatment technology, long-short pile composite's design theory is still in primary phase, and there are no explicit settlement calculation methods in active codes. So it is necessary to study the working mechanism and the methods of settlement calculation. In this paper, the mechanics of long-short pile composite foundation are fully discussed. Meanwhile, based on the shear deformation method, the Mylonakis & Gazetas models about mutual action between two piles and the one between pile and soil are introduced, Considering the performance of cushion, the flexible factors of mutual actions are provided. Then the settlement calculation of long-short pile composite foundation which can consider the mutual actions between pile, soil and cap is deduced, and the correlated program is also developed. Finally, an engineering example is discussed with the method. A comparison shows that calculated results and measured data from a field test pile are in a good agreement, indicating that the presented approach is feasible and applicable in engineering practice.

• Geotechnical Engineering
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• v.38 no.1
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• pp.8-25
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• 2022

• Journal of the Korean GEO-environmental Society
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• v.20 no.3
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• pp.31-38
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• 2019

To determine the optimum dynamic load test analysis for PCFT (Prestressed Concrete Filled steel Tube) hybrid composite piles that PCFT piles are connected to the top of PHC piles, the dynamic load tests and CAPWAP analyses were performed on two hybrid composite piles with steel pipe and PCFT piles as upper piles. The results of the dynamic load tests and CAPWAP analyses showed that the particle velocity measured in PCFT hybrid composite piles was equal to the wave speed of PHC piles when the strain gauges and accelerometers are attached to the surface of inner composite PHC pile after removing the steel pipe in the upper PCFT pile. In addition, when assuming that the material of that upper PCFT pile was the same as that of the lower PHC pile and the cross-sectional area of the steel pipe in upper PCFT pile was converted to that for concrete through the pile model (PM) in CAPWAP analysis, the accuracy of the CAPWAP analysis result for PCFT hybrid composite piles was very high.

• Journal of the Korean GEO-environmental Society
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• v.15 no.8
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• pp.51-58
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• 2014

In this research, the composite grounds including original clay and soil-cement were constructed for conducting uniaxial compression test. Strength and deformation properties were analysed using results of laboratory tests with variations of water content of clay, replacement ratio and cement content. Numerical simulation using 3D distinct element method was conducted for soil cement. For strength of composite ground that contains more than cement contents of 15 %, it is more effective to increase cement content than increase of replacement ratio. Strength and elastic modulus of composite ground could be predicted by regression equations using uniaxial compression strength of clay, cement content of soil cement and replacement ratio. For strength and elastic modulus of soil cement, which is most important things for predicting final strength and elastic modulus of composite ground, numerical simulation using the distinct element method adapted bonding model could be used to verify laboratory test, and predict strength and elastic modulus.

• Journal of the Korean GEO-environmental Society
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• v.24 no.5
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• pp.21-28
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• 2023

In this paper, an experimental study was conducted to present the properties of rapid hardening composite mat, and a numerical analysis was carried out to analyze the slope protection effect of the mats based on ground conditions, rainfall, slope gradient and soil height. As a result, the application of rapid hardening composite mat increased the slope safety factor in all conditions, and the increase rate of safety factor showed an average of 40% increase both in dry and rainy seasons. Through these research findings, the protective effect of the rapid hardening composite mat on sloping surfaces has been proven, and it is suggested that the rapid hardening composite mat is suitable for application in areas where slope failure or collapse is expected.

• Journal of the Korean GEO-environmental Society
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• v.1 no.1
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• pp.65-70
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• 2000

Recently, soil-bentonite mixtures are frequently used as impervious liners for waste disposal sites. In the present work, bentonite composite liner systems have been developed by utilizing Korean zeolitic bentonites. The geomechanical properties of the liner systems, such as strength hydraulic conductivity, etc. have also been studied. The laboratory and field test results showed that uniaxial strengths of the system were improved by addition of bentonite and CaO-based additive to the upper and lower layer of the liner systems, respectively. Hydraulic conductivity values measured on field liner systems showed less $1{\times}10^{-3}cm/s$, which is considered to be minimum regulation requirement for waste disposal sites.

• Journal of the Korean GEO-environmental Society
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• v.2 no.3
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• pp.57-69
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• 2001

Sand pile is widely used as a ground improvement method. Although the primary purpose of constructing sand pile is accelerating consolidation, composite ground effect also can be gained by constructing sand pile. This study was accomplished to understand composite ground effect on the ground improved by sand piles which were applied as vertical drainage material when area replacement ratio was small relatively. For determining bearing capacities of origin ground and sand piles and analysing interaction between embankment and origin ground, bearing tests and earth pressure monitoring are performed. From the results, it turned out that the contribution of sand pile as a load bearing mechanism is not substantial. However, the bearing capacity of sand pile was increased to sixty percentages when compared with origin ground. The increasement of bearing capacity could be caused the change of consolidation characteristics during the process of consolidation by overburden load. Therefore, the composite ground effects depending on stiffness increasement of sand pile would be estimated as a factor decreasing consolidation settlement.