• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.4
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• pp.208-213
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• 2009

Artificial lightweight aggregates were produced by using bottom ashes and dredged soils from coal power plant. The amount of glassy phases on the aggregate surfaces, specific gravities, absorption rates, and observations of cross-sectional surfaces were compared according to the compositions, sintering temperatures, and the amount of coating. It is concluded that surface modification by 10 % $CaCO_3$ coating on the aggregate surfaces enhances the properties of aggregates as follows: Specific gravities were controlled by depressing formation of large pores in the aggregates. Sticking phenomena among aggregates during the sintering process was drastically decreased by reducing glassy phases on the aggregate surfaces. Pumping problems during the application of ready-mix concretes containing lightweight aggregates having high value of absorption rates could be solved by reducing the absorption rate.

• Journal of the Korean Geotechnical Society
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• v.27 no.5
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• pp.5-15
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• 2011

Recent increase of large scale construction near costal area has also increased the application of soft ground treatment. As a result, solidification with cement and lime which increases stability and durability of soils, is frequently used for surface layer stabilization in soft ground site. While stabilization of very soft clay with high plasticity and compressibility has widely been studied, studies on silty clay with low plasticity and compressibility are relatively rare. In this study, after stabilizing low plasticity silty clay of Songdo area with cement and lime under various water contents, mixing ratio, and curing time, uniaxial compression test and plate load test were performed. Strength properties from both tests were considerably consistent. And trackability of construction equipment on the treated surface layer of dredged land was estimated. Finally, optimum mixing condition for Songdo silty clay was proposed.

• Journal of the Korean Geosynthetics Society
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• v.14 no.1
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• pp.33-41
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• 2015

In this study, laboratory tests (flow, unit weight, unconfined compressive strength and bleeding tests) were performed to evaluate engineering properties of treated soil to improve pipe mixing method. As result, flow and bleeding properties are proportional to the water contents. The unit weight and unconfined compressive strength is decreased as the water contents increased. Comparing equipments contact pressure with bearing capacity of the mixed soil for dozer, backhoe and belt conveyor are immediately appliable. The applicable water content range is estimated from 80% to 200% by pipe mixing method using cement. Also, The design chart is developed from the results.

• Journal of the Korean Geotechnical Society
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• v.15 no.5
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• pp.281-290
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• 1999

The coastal area, particularly along the West and South coasts in Korea, is often reclaimed with dredged marine-clay to meet the demand of land capacity. A large number of ground improvement techniques are developed for such a newly formed soft clay deposit. However, the quick lime column method, which is effectively used for the purpose of ground improvement in the other countries, is seldom applied in Korea. This study, therefore, focuses on the development of appropriate soft soil improvement technique by using quick lime column. A model test as well as finite element analysis was conducted to identify the consolidation characteristics around the lime column. Although actual pore water pressure measured from model tests does not coincide with the predictions made by finite element method and Chen ＆ Law's theoretical formula, their trends are quite similar. It is revealed from this study that the pressure caused by the expansion of lime column affects considerably the consolidation characteristics of the surrounding ground.

• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.233-241
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• 2003

Geotextile tube is hydraulically filled with dredged materials and has been applied to coastal protection and scour protection, dewatering method of slurry, and isolation of contaminated material. Recently, geotextile tube technology is no longer alternative construction technique but suitable desired solution. In this paper, the numerical analysis was performed to investigate the behavior of geotextile tube with various properties of geotextile sheet and hydraulic pumping conditions. Numerical analysis was executed to compare with the results from the large-scale field model tests, and also with those of plane strain analysis and 3-D FEM analysis. A geotextile tube was modeled using the commercial finite element analysis program ABAQUS and the one-quarter of tube was modeled. Behavior of geotextile tube during the hydraulic pumping procedure was analyzed by comparing the large-scale field model test and numerical analysis. The shape variation and maximum tube height between the numerical analysis results and large-scale filed test results are turned out to be in a good agreement.

• Asian Journal of Turfgrass Science
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• v.16 no.2
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• pp.75-83
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• 2002

The back-filled soil of the New Incheon International Airport construction site was reclaimed with sea sand in near the Young-Jong island. The primary study was carried out from August 1993 to June 1997 to study soil amendment and to select salt resistance turfgrass species. This study dealt with low maintenance area that included most part of open space of airport site. The second experiment, from October 1996 to August 1998, focused on soil amendment and selection of turfgrass species for alongside runway where turf area was maintained. Through two previous studies, propagation methods with zoysiagrass were tested for alongside runway and surrounding areas at 1998. The study of construction methods with zoysiagrass, vegetative propagation showed better results on visual quality and cover rating compare with seeding propagation. However, significant different between vegetative and seeding propagation was not showed on visual quality and drought tolerance after one year of plot establishment. The cover rating by seeding construction methods reached in excess of 70% of limitation suggested by the Incheon International Airport Cooperation. Zoysia net and sprigging net methods were the most suitable where there requires rapid and high rate of ground cover. Seeding propagation should be acceptable to obtain a resonable cover rating where there allows relatively longer period of completion. Therefore, it should be possible to attain a proper rating of ground cover on the site of open space, alongside runway or areas similar to the New Incheon International Airport which is being built on dredged seashore sand. However, the methods of soil amendment, selecting salt tolerance species, and proper construction procedure should be considered at the a time.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.17 no.6
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• pp.1-15
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• 2014

A dredging on erosion control dam has been enforced without evaluation the factors that affect the dredging. In addition, there is the negative effect much more than positive effect by dredging on erosion control dam. Therefore, this study was carried out to develop evaluation indicators and to suggest fieldbook in order to determine whether sand deposits at erosion control dam should be dredged up or not. The most important six evaluation indicators that can decide to dredge up at erosion control dam were obtained from three round delphi technique and were selected in the following order: the current sand deposit ratio(0.339), existence of cultivated land and house downstream(0.276), the slope of streambed(0.162), the amount of movable soil and gravel(0.118), the history of any disasters(0.063), the basin area(0.043). The weighted score for each evaluation indicator were acquired from AHP analysis with respect to the degree of importance and then the modified weighted score for actual measurements were classified as three categories: large(2.53), medium(1.60) and small(1.01). Based on delphi technique, erosion control dam dredging evaluation fieldbook introduced the four evaluation indicators out of the total six evaluation indicators and two low effected evaluation indicators were excluded. This results showed that the values for reliability analysis and consistency ratio were acceptable.

• Geotechnical Engineering
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• v.14 no.5
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• pp.235-247
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• 1998

The IIA(Inchon International Airport) which will function as the HUB airport in the northeast Asian region in the upcoming 21th century will be located in the reclaimed land with sand dredged in the vicinity of project area between Youngjong and Yongyu islands. The original ground is composed of soft clayey silt (ML) or silty clay (CL). The reclaimed land is classified as being SP-SM and having poor gradation of Cu<3 which resulted in the anticipation for difficulty in compaction (compaction index = 0.6~0.7). This anticipation shedded light on the necessity of performing test compactions for the thickness of 3~5meters of reclaimed land, aiming at the discovery of effective and economical compaction method. Upon the call for the test compaction performance 4 different compaction methods have been selected for trial from the research done on the international and local academic papers, past experience with compaction works, and their written materials. For the precise interparetation of test results, the ground survey and measurements have been performed. The Hydraulic Hammer Compaction has been chosen as the most optimum in accordance withe the test results.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.5
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• pp.1083-1096
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• 2015

This study utilised Computational Fluid Dynamics(CFD) for preliminary assessment of mixing efficiencies of 2-phase fluids in a pipe at which a slurry flow and an injected solidifier join, for the purposes of reducing trial-and-error-based instances of physical experiments and conducting the overall research in an economical way. Using OpenFOAM$^{(R)}$, we simulated behavior of 3-phase fluids under 18 different settings generated by changing diameters of a dredged soil transportation pipe, a quality improving material injection pipe and the confluence angle. While difference in mixing efficiencies amongst the instances was insignificant, discernible boundary layers amongst the materials were observed in all of the instances. In order to break the boundary layers, we designed a substructure inside a pipe and found out that it could remarkably improve mixing efficiencies particularly for short distance applications.

• Korean Journal of Ecology and Environment
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• v.41 no.2
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• pp.166-173
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• 2008

Chemical forms and release potential of heavy metals were studied in the lime treated sediment of lake Chungcho. Chemical forms of heavy metals were analyzed using a sequential extraction method, and release potential of heavy metals was evaluated by the ratio of the content of labile forms to total metal one. Dominant form of Cd, Cu, Pb, and Zn in the untreated sediments was organic/sulfidic form that is stable in the reducing environment such as the bottom of Lake Chungcho. With liming of the sediment, the chemical forms of studied metals were greatly changed from organic/sulfidic form to adsorbed and reducible form, especially Cd and Cu to adsorbed and reducible form, but Pb and Zn to reducible form. It is believed that increase of unstable form of heavy metals in the sediments by liming was caused by the increase of pH of the pore water at the expense of organic/sulfidic form. Thus, we concluded that the liming approach currently used in the treatment of dredged sediments might cause the increase of labile form which is easily dissolved, and may increase the release of metals from the sediment into overlying water.