• Journal of the Korean Geotechnical Society
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• v.30 no.9
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• pp.19-28
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• 2014

It is necessary to understand the behavior of the soils for the dredging constructions. The objective of this study is to estimate void ratio and density changes of the dredged soils by using the geophysical testing methods. A series of laboratory tests is performed to obtain geotechnical index properties of the specimen, retrieved from the west coastal of Korea. The sedimentation and self-weight consolidation tests are carried out with observing changes of the interfacial height and the elastic wave velocities. The same amounts of the soils are poured into the testing column at intervals of 12 hours until the interheight reaches to a certain level. After the completion of the sedimentatation and self-weight consolidation tests, downward permeability test is performed to assess a tidal influence in the nearshore. The mini resistance cone is penetrated into the specimen to measure the electrical resistivity with depth. All tests are completely finished, the weight of specimens are measured to calculate the void ratio with the depth. Experimental results show that the aspects of the self-weight consolidation are invisible during dredging process because of rapid sedimentation characteristics of ML. However, the elastic wave velocities increase with increasing in the effective stresses. During permeability test, measured permeability and the elastic wave velocities maintain almost identical values. Void ratio based on the elastic wave velocities changes linearly with time during the step dumpings. Void ratio estimated by the electrical resistivity represents the repeatedly layered depositions according to the step-by-step dumpings. Void ratio determined by soil sampling is similar to those of elastic waves and electrical resistivity profiles. This experimental study demonstrates that the geophysical testing methods may be an effective method for evaluating the behavior of dredged soils.

• Journal of the Korean GEO-environmental Society
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• v.15 no.3
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• pp.33-40
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• 2014

In this paper, mechanical and germination characteristics of stabilized dredged soils were investigated to recycle dredged soil in eco-friendly manner such as waterfront construction. Non sintering binder (NSB), which was developed by using interchemical reactions between slag, high-calcium fly ash, alkali activator on the dredged marine clay, was added to dredged soil. Ordinary portland cement was also used for the comparison of two binders. Experimental tests such as flow test and unconfined compressive test were carried out to evaluate characteristics of stabilized dredged soil. Leaching test, pH measure, vegetation germination test were also conducted to consider environmental applicability. The unconfined compressive tests shows that unconfined compressive strength (UCS) also increases with the increase of curing time and mixed ratio. UCS of NSB mixtures were higher than those of OPC mixtures. Germination tests showed that germination and sprouting date are better in NSB mixture than OPC mixture. It can be explained that germination decreased as pH and 7-day strength increased.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2009.10a
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• pp.57-60
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• 2009

• Journal of Industrial Technology
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• v.20 no.A
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• pp.93-100
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• 2000

This research is to investigate the self-weight consolidation settlement and desiccation shrinkage settlement of soft marine dredging clay by performing numerical and experimental works. Large column test were carried out investigate the consolidation settlement considering effect of the self-weight and desiccation shrinkage, and centrifuge model test was also carried out investigate self-weight consolidation settlement. Results of centrifuge model and large column experiments about changes of settlement with time were analyzed by using the numerical technique of explicit finite difference method considering effect of the self-weight and desiccation based on the finite strain consolidation theory. Centrifuge model test results were in relatively good agreements with analyzed results in terms of self-weight consolidation settlement with time. Large column test results showed quite different values from the numerically estimated one, carried by experimental conditions.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.4
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• pp.185-191
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• 2010

To effectively utilize resources of reject ash and dredged soil, globular shape-formed artificial lightweight aggregate were manufactured in 8~10 mm size. Starting materials were changed various grading and composition, sintered at $1050{\sim}1250^{\circ}C$. The specific gravity, water absorptance of artificial lightweight aggregates were measured on the basis of the KS. In this study could make a prediction about application of bloating mechanism by ferrous materials and alkali/alkali-earth oxide at high temperature.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.744-748
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• 2010

4대강 살리기 사업에 있어 하천 준설 및 다목적 보 설치는 주요하천 상 하류의 일괄적인 준설을 통한 통수단면 확보로 홍수 소통능력을 극대화 하고, 친환경적 보설치를 통해 하도정비 실시이후에도 현재의 갈수위 이상의 수위를 유지하면서 홍수피해저감효과를 극대화하는 것을 목표로 한다. 4대강 사업시 콘크리트 형식으로 건설될 다목적 보는 월류식 구조물이지만 보의 저부에서 발생하는 양압력이나 기타 재하 하중과의 조합으로 인해 전도나 활동을 일으킬 수 있는 가능성을 가질 수 있고, 보의 규모가 커지고 가동보 등의 복합적인 형태를 가질 경우 보의 붕괴는 콘크리트 중력식 댐의 붕괴와 비슷한 양상을 가질 것으로 판단된다. 본 연구에서는 월류 구조물이 붕괴되었을때 상 하류 하천에 미치는 영향을 분석하고자 하였다. 자연하천 내의 보 붕괴 및 그에 따른 수위상승으로 인한 제방 붕괴시 실제 범람원에 안정적으로 적용가능한 고정확도 2차원 홍수범람 모형을 평가하였고, 가상하도 및 실험하도에 대한 적용을 실시하였다.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1222-1228
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• 2010

본 연구는 인천 송도국제도시 중앙대로 구간의 도시철도공사와 인접한 연약지반 및 준설 매립층 개량공사와 관련하여 설계의 적정여부 판단 및 시공방안을 제시하기위해, 본공사에 앞서 시험시공을 통해 C.G.S의 개량효과를 확인하고 분석하였다. 시험시공결과 당초 설계제원에서 계획했던 개량효과가 만족되는 것으로 분석되었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.11
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• pp.6943-6951
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• 2014

The trophic state assessment of the Hwoiya reservoir was estimated using the Trophic state indices (TSIs) of Carlson and Aizaki using the transparency and concentrations of chlorophyll-a and total phosphorus obtained from two sites of the reservoir. The TSIs assessments showed that eutrophic phenomena occur frequently in the Hwoiya reservoir. In addition, strategies to reduce the phosphorus especially would be prepared because the Hwoiya reservoir exceeded phosphorus-limiting state of 17 < TN/TP (total nitrogen/total phosphorus). Three scenarios for a simulation of the dredging effect of sediments on the water quality using the WASP7 model were made at two sites, which were 10% (scenario 1), 40% (scenario 2) and 60% elution of the pollutants from sediments (scenario 3). In the most elution case (60%), scenario 3, it was considered that 6.4% TN and 9.3% TP at site 1, and 3.9% TN and 5.6% TP at site 2 could be reduced.

• Journal of the Korean Geotechnical Society
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• v.22 no.5
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• pp.13-26
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• 2006

The purpose of this study is to examine the method of liquifaction potential occuring at the reclaimed land in Incheon district and to compare the result obtained by the method based on the earthquake of 6.5 magnitude. In addition, the effects of ground improvement and liquifaction potential were evaluated on the basis of SPT and CPT, which have been performed before and after the compaction pilot test. As a result, we realized that the bigger the energy of dynamic compaction test was, the better effect we got. After the dynamic compaction test, as the strength of ground increased, the safe factor also increased. It was evaluated that the method of dynamic compaction improved the seismic performance. Accordingly, the method of the quality control of reclaimed land based on dynamic compaction method was presented.

• Journal of the Korean GEO-environmental Society
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• v.11 no.4
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• pp.51-59
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• 2010

This article is a case study for the example of the foundation design, in the project area of the silty sand layer that is spread shallowly with loose status, to make the site for a structure and build it up. The site is located on the dredged and reclaimed land in Gun-San and In-Cheon that is formed the silty sand layer with loose status range around 10 meters underground level, the solid ground for the lower pile is shown around 20 meters underground level. Therefore, this area has to be done by ground improvement when applying for the shallow method of foundation. Dynamic compaction method considering the conditions of the design loads in each zone has to be decided through comparative review on the method of foundations and pilot field test was conducted, and drilling investigation and plate bearing test were achieved as well. The analysis results of the tests prove that stability against bearing capacity was acquired by ground improvement effect.