• Water for future
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• v.29 no.3
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• pp.177-186
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• 1996

QUAL2E model was applied to assess the water quality variations due to dredging of the bottom deposit in the downstream of the Nakdong River. A variedflow analysis was performed for the reach of Namji to Nakdong Estuary to estimate the hydraulic parameters. BFGS (Broyden-Fletcher-Goldfarb-Shanno) method was applied to determine the optimum reaction parameters and model verrification was performed based on these. Water quality modeling of dredging effects for BOD and DO in the reach was performed under low and average flow conditions and alternatives. It revealed that dredging had significant effedcts on the improvement of water quality in the reach.

• Journal of the Korean Geosynthetics Society
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• v.16 no.4
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• pp.57-66
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• 2017

Self-weight consolidation test and soil property of dredged soil at Incheon habour route were analyzed to determine the initial dredging reclamation amount, reclamation depth, and estimating the required time of self-weight consolidation with calculation of the final planned height of dredging reclamation site. The moisture content, void ratio and ratio of volume change with elapsed time after throwing were estimated through Yano's empirical equation. As a result, there was a less variation in elements when fine-grained soil content was low as similarly to the behavior of coefficient of sedimentation-consolidation, Cs and the highest variation was shown at the fine-grained soil content of 50%. The retention ratio according to the fine grained soil content that could reinforce the comprehensive aspect of retention ratio for each particle size presented in the standard of estimate for reclamation construction work was calculated and presented using the calculated ratio of volume change.

• Geotechnical Engineering
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• v.10 no.1
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• pp.71-82
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• 1994

According to the field measurement of dredging-reclaimed land, the actual self-weight consolidation settlement has been frequently reported to be less than the predicted values based on the laboratory tests results. The author estimates that one of the reasons is the reduction of the compressibility due to the sedimentation of the dredging material, Furthemore, the aging effect is ignored in the consolidation characteristics of the very low stress range as a pump dredging-reclaimed land. In this paper, a series of seepage consotidation tests has been carried out by applying the seepage force to the specimen prepared by sedimentation in consolidmeter in order to clarflfy the aging-effect on the compressibility of dredging clayey soil, Also, with a view to overcome unstable consolidation solution occurring in the case where the initial water content is higher as pumpdredging reclaimed land, the finite difference analysis technique using predictorforrector method is suggested that it gets good agreement with ezperimental results. Finally, the compressibility of the dredging clayey soil is depended on self-weight consolidation time.

• Journal of the Korean Geosynthetics Society
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• v.12 no.3
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• pp.87-94
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• 2013

As sediment contamination problems have recently been raised in Korea, the need for technologies to remove contaminants in sediments has increased. Contaminated sediments in Korea has been annually dredged and treated using processes of coagulation/flocculation, sedimentation on barges, dewatered and dried at prepared site, and then disposed at a landfill site, which is very costly, and only a limited landfill space available in Korea. Contaminants in media containing a high percentage of silt and clay sized particles, typically, are strongly adsorbed on the particles and difficult to remove. Particle separation processes that separate the fine clay and silt particles from the coarser sand and gravel and concentrate the contaminants into a smaller volume of sediment that can be further treated of disposed of, are very effective in the post step processes. In this study are to test the feasibility of treating dredged sediments using a hydrocyclone process, and to estimate design parameters for a pilot scale test. A hydrocyclone was operated to separate larger particles from the sediments. It was found that the particle separation was greatly affected by the solid contents and inlet pressure in the hydrocyclone.

• Journal of Korea Water Resources Association
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• v.48 no.9
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• pp.743-756
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• 2015

It is necessary to evaluate the effect of dredging and weir operation on the flow and long-term bed change for river management. Especially, large scale river treatment project, with dredging or weir installation and operation, can increase the instability of riverbed in tributaries as well as mainstream. This study focuses on the effect of weir installation and dredging on the long-term bed change in Nakdong river (Gangjeong- Goryeong Weir~Dalseong Weir) and its tributary (Geumho river). HEC-6 model has been used to analyze the amount of long-term bed change and sediment transport resulted from the river treatment including dredging or weir installation. From the result, it was concluded that a large scale river treatment can accelerate and increase the long-term bed change both in mainstream and tributary.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.559-563
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• 2012

본 연구에서는 4대강 살리기 사업으로 인한 물리적 환경변화와 그에 따른 하천수위 저하 효과분석을 위하여 3차원 수리동역학 모형인 EFDC를 채택하였다. 대상구간은 낙동강수계로 선정하였으며 준설 전 후 지형 및 다기능보 제원은 4대강 살리기 사업 실시설계보고서를 바탕으로 조사하였다. 낙동강 수계 8개 다기능보의 가동보는 모두 개방하는 조건으로 구축하였으며 계획홍수량 조건에서의 수리특성을 모의한 결과, 수위저하 효과는 평균적으로 1.56 m인 것으로 분석 되었다.

• Journal of the Korean Geosynthetics Society
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• v.15 no.1
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• pp.71-81
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• 2016

To evaluate the effects of magnetic force for transporting the dredged soil, magnetic energy inducing device was installed at the dredger. The whole length of transporting pipeline reaches more than 8.5km and the efficiency of the system and the characteristics of the flow are critical factors. The main parameters which govern the flow are flow-rate, velocity, concentration and slip-layer's condition, so in the field test monitoring system was applied to check the real time conditions of the closed circuit flow and the main parameters. From analyzing the relation between the dredged soil amounts and the pump power, it can be concluded that the magnetic forces effect on the transporting system, increase the transporting quantities of dredged soil and decrease power consumption of the pump.

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.167-178
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• 2000

An experimental study on step up filling method is carried out to reinforce the Yano method which is widely used to estimate volume ratio and self-weight consolidation settlement in reclamation area. This method considers actual reclamation construction in which dredged clay is continuously filled and rising of deposit height is presented as a result of volume decrease by height rising and self-weight consolidation. It measured the relationship between filling velocity and deposit rising velocity; calculated the total filling height which is needed to achieve the planned final deposit height, and its solid height and the time which is taken to finish the planned final deposit height; and on the basis of these calculated parameters, predicted the self-weight consolidation and volume change ratio in reclamation construction. Yano method is also used to predict the same conditions. 29.8% in self-weight consolidation, 31.1% in volume ratio, 40% in void ratio and water content is underestimated in Yano method compared to step up filling method.

• Journal of the Korean Geotechnical Society
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• v.24 no.9
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• pp.33-40
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• 2008

This paper describes the performance of ground improvement project using prefabricated vertical drains of condition, in which approximately 10m dredged fill overlies original soft foundation layer in the coastal area composed of soft marine clay with high water content and high compressibility. From field monitoring results, excessive ground settlement compared with predicted settlement in design stage developed during the following one year. In order to predict the final consolidation behavior, recalculation of consolidation settlements and back analysis using observed settlements were conducted. Field monitoring results of surface settlements were evaluated, and then corrected because large shear deformation occurred by construction events in the early stages of consolidation. To predict the consolidation behavior, material functions and in-situ conditions from laboratory consolidation test were re-analyzed. Using these results, height of additional embankment is estimated to satisfy residual settlement limit and maintain an adequate ground elevation. The recalculated time-settlement curve has been compared with field monitoring results after additional surcharge was applied. It might be used for verification of recalculated results.

• Journal of Internet Computing and Services
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• v.20 no.6
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• pp.47-54
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• 2019

Social dredging of various river facilities, such as dams and agricultural reservoirs currently being constructed, should be done to ensure stable reservoirs. However, it is difficult to find a system that tells the exact amount of water in real-time in a reservoir or dam. These measurements require an automated system to collect and analyze highly accurate data in real time. In this study, we propose a method to measure the amount of water and soil of reservoir in real time through multi-division volume calculation using a drone, and this method can detect sediment conditions in real time and determine the exact timing and scale of dredging.