• Title/Summary/Keyword: 준설매립점토

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An Equation for the Prediction of Material Function of Super Soft Clay (초연약 점토의 구성관계 산정식)

  • Kang, Myoung-Chan;Lee, Song
    • Journal of the Korean Geotechnical Society
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    • v.19 no.1
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    • pp.221-228
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    • 2003
  • In land reclamation construction using marine clay, a measure of material function, that is, the relation between void ratio-effective stress and permeability, is very important aspect for the prediction of self-weight consolidation behavior. But reclaimed ground has very high water content, so there are many difficulties in the laboratory test for measuring material function. For this reason, some researches are carried out using slurry cconsolidometr to measure material function. In this study, material function was measured using slurry consolidometer, and to overcome the shortcoming of researches using slurry cosolidometer, an equation for the prediction of material function was proposed on the basis of column test's parameter. Material function was determined through low stress consolidation test and permeability test, and it also was calculated with the equation using column test parameter. The continuity of material function could be confirmed through these tests. Material function is easily determined with the equation proposed in this study, and can be used for the prediction of self-weight consolidation behavior.

Sedimentation & Consolidation Behaviour of Dredged Clay Fill (준설매립 점토지반의 침강 . 압밀거동)

  • 이승원;지성현;유석준;이영남
    • Journal of the Korean Geotechnical Society
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    • v.16 no.4
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    • pp.149-156
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    • 2000
  • Sedimentation and self-weight consolidation tests in cylinder and large model tank and field measurement such as settlement and pore water pressure at each layer by wireless automatic instrumentation system were carried out to investigate the behaviour of dredged marine clay fill. The consolidation behaviour for each reclaimed layer was analyzed from these measured data and numerical analysis result using finite strain consolidation theory. It was fond from this study that the consolidation behaviour of dredged clay fill is heavily dependent on the filling process.

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Shear Strength Characteristics of Artificial Soil Mixture with Pond Ash (매립석탄회가 혼합된 인공혼합토의 전단특성)

  • Kim, Kyoungo;Park, Seongwan
    • Journal of the Korean GEO-environmental Society
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    • v.14 no.10
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    • pp.39-47
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    • 2013
  • Recently, there have been various domestic construction activities related to the reclamation of the dredged soils to expand the land use. However, the reclaimed grounds made of the dredged soils cause various problems due to highly compressible and low shear strength nature. Particularly, this nature induces huge problems in case of the harbor facilities and road construction on the reclaimed sites. Furthermore, in the reclamation activities, the marine dredged soils are often used instead of the well sorted sand, which induces problems of compressibilities. Therefore, in this study, the mechanical characteristics of artificial soil mixture of kaolinite representing the marine dredged soils and the pond ash. A large consolidometer is designed and manufactured to produce the artificial soil mixture. To represent various mixing ratio between the fly ash and bottom ash in the pond ash, six samples with the same stress history are made with different mixing ratio among kaolinite, bottom ash and fly ash. Isotropically consolidated and undrained compression tests are performed to investigate the shear characteristics of soil mixtures. Based on the experimental results, as the components of mixed ash increase, the friction angle increase and the cohesion values decrease. Also, the porepressure parameters at failure, Af increase with the mixing components of the pond ash. The portion of bottom ash has more impact on the shear behavior than that of fly ash.

A Case-study of Compression Index Prediction on Very Soft Clay (초연약 점토지반 압축지수 추정에 관한 연구)

  • Kim, Byeong-Kyu;Lee, Song
    • Journal of the Korean Geotechnical Society
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    • v.31 no.4
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    • pp.13-18
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    • 2015
  • Considering dredged ground is consolidated more than one meter, Compression index prediction is very important. But, UD-sampling and consolidation test are impossible because of high moisture content and weak shear strength. This paper demonstrates the compression index relation, $C_{c(d)}=F(e_d,C_c)$, between in-situ and dredged clay using N. Keith Tovey's Omega point and soil physical properties. Good relationship is confirmed between proposed formula and measured primary consolidation result on dredged ground in The Republic of Korea.

A Study on Characteristic of Sedimentation-Consolidation Conduct for Dredged Soil through Geo-Centrifuge Test (원심모형실험을 이용한 준설토의 침강압밀 거동 특성)

  • Park, Hyunchul;Kang, Hongsig;Sun, Seokyoun;Park, Jongseo;Ahn, Kwangkuk
    • Journal of the Korean GEO-environmental Society
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    • v.18 no.2
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    • pp.59-65
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    • 2017
  • The costal reclamation construction is for making reclaimed land by dredging marine clay with seawater, and then bringing the dredged soil into the reclaimed land. During the process, the dredged soil in the reclaimed land undergoes the sedimentation-consolidation process. Among the processes, the consolidation is a very critical factor when planning reclaimed land because of its requiring time and settlement. In order to predict the requiring time and settlement, the Column test, which was suggested by Yano, has been usually used in the nation. However, the test method needs a very long time to identify the characteristic of sedimentation-consolidation of dredged soil. Therefore, in this study, in order to supplement the weakness of the Column test which needs such a long time, and in order to identify the characteristic of the sedimentation-consolidation for dredged soil in a short time, the Geo-centrifuge test was examined as an alternative method. The result considered that Geo-centrifuge test would be useful to identify the characteristic of sedimentation-consolidation for dredged soil efficiently.

Consolidation Behavior of Poor Mixed Soil-Cement (빈배합 시멘트 혼합점토의 압밀 특성)

  • Lee, Jongmin;Kwon, Youngcheul;Lee, Heunggil;Lee, Bongjik
    • Journal of the Korean GEO-environmental Society
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    • v.11 no.4
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    • pp.25-31
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    • 2010
  • The amount of dredging clay will be greatly increased by the eco-rive project and port development in Korea. Geotechnical engineers have thrown their efforts into the new ways for effective re-uses of the dredging clay such as the material for reclamation, and so on. However, very high initial water content and low strength causes unexpected difficulties in the aspect of trafficablility or time for consolidation. Therefore, the injection of cement stabilizer is used as one of ways to improve reclaimed ground. However, it also makes an argument by heavy metal from cement stabilizer. In this paper constant rate of strain consolidation test and normal consolidation test were performed to investigate behavior characteristics of the consolidation about soil-cement include lean mixed cement to reduce the environmental loads by the cement. The experimental results of consolidation characteristics about soil-cement include lean mixed cement influenced by mixing ratio. Especially it was observed that mixing ratio of 4%~6% leads not only the reduction of consolidation settlement, but time for consolidation.

A Study on Self-Weight Consolidation Characteristics in Dredged and Reclaimed Clay (준설매립 점토의 자중압밀 특성에 관한 연구)

  • Lee, Song;Yang, Tae Seon;Hwang, Koou Ho
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.14 no.4
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    • pp.953-963
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    • 1994
  • Treatment techniques of soft clay layers is needed sophisticated technology in civil engineering. Especially, dredged and reclaimed clay has high liquid limit and water content, so it is difficult to use. Now it comes to the applicability as good construction materials by predicting the behaviors. This paper is to evaluate the characteristics of sedimentation and self-weight consolidation of extremely soft clay, and is to find the way of applying model test result of reconstructing the in-situ condition to design. The consolidation properties of soft clay layers changing the size of the cell are investigated by large-scale consolidation test apparatus and the behaviors of self-weight consolidation are predicted by numerical analysis.

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Application of Ultrasonic Energy to Accelerate Consolidation of Soft Ground (연약지반 압밀 촉진을 위한 초음파 에너지의 활용)

  • Park, Ji-Ho;Hwang, Jung-Ha;Shim, Seong-Hyeon;Kim, Young-Uk
    • Proceedings of the KAIS Fall Conference
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    • 2008.05a
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    • pp.139-141
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    • 2008
  • 최근 우리나라는 국토면적을 넓히기 위하여 많은 지역에 준설 및 매립 공사를 수행하고 있다. 준설 및 매립공사 시 주재료로 사용되는 해성점토는 매립 초기에 매우 연약한 지반을 형성하게 된다. 이에 빠른 구조물 시공을 위하여 대상지반의 압밀을 촉진시키는 다양한 공법이 활발히 연구되고 있다. 본 연구는 새로운 압밀촉진 공법개발을 위한 기초시험으로써 초음파 에너지를 연약지반 처리에 활용하고자 자체 고안된 초음파 발생장치를 적용하여 소규모 및 대형시험을 수행하였다. 시험에 사용된 연약 지반 점토시료는 시험조건의 일관성을 유지하기 위하여 자체개발한 원심력 시료 성형기를 사용하였다. 초음파 적용에 따른 압밀시험결과 매우 큰 압밀량의 증가를 확인할 수 있었으며 대형 시험의 경우에도 빠른 간극수압의 소산을 확인 할 수 있었다. 연구결과 초음파가 점토의 압밀시간을 단축시키는데 효과가 크다는 것을 볼 수 있었고, 차후 초음파를 통한 다양한 압밀촉진공법이 개발될 수 있다는 가능성을 확인 할 수 있었다.

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A Study on the Prediction of Shear Strength and Determination of the Embarkation Time of Equipment in Dredged Clay Fills (준설점토지반의 전단강도 예측 및 장비투입시기 결정에 관한 연구)

  • Kim, Hong Taek;Kim, Seog Yol;Kang, In Kyu;Kim, Seung Wook
    • Journal of the Korean GEO-environmental Society
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    • v.2 no.3
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    • pp.47-56
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    • 2001
  • In the present study, mainly to determine the embarkation time of equipment in dredged clay fills, an analytical approach is performed to predict a variation of the undrained shear strength in the outermost layer. In this approach, Gibson's non-dimensional linear constant defining the relationship between the void ratio and the effective stress is employed. Also in this approach, void ratios and settlements associated with the volume change due to the self-consolidation and the desiccation shrinkage are evaluated at various elapsed times based on the finite difference solution technique proposed by the authors(1999) and the developed computer program named as DSCON. Predicted results(water content ratio, unit weight and undrained shear strength) are compared with those of laboratory model tests conducted with soil samples obtained from the Koheung site. Based on the predicted undrained shear strengths, possible embarkation time of a equipment is also evaluated. In addition, further analyses are made to indirectly verify the efficiency of the analytical approach proposed in the present study using the PSDDF computer program which can consider the drainage efficiency.

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Assessment on Consolidation Material Function and Initial Stress for Soft Ground by Hydraulic Fill the at Southern Coast of Korea (남해안 준설매립 연약지반에 대한 압밀 물질함수 및 초기응력 산정)

  • Jeon, Je Sung;Koo, Ja Kap
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.15 no.4
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    • pp.136-145
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    • 2011
  • For a massive project related to building national industrial complexes on a soft ground applied to PVD after dredging and hydraulic fill, laboratory tests were carried out using undisturbed sample taken from various depth. Piezocone penetration and dissipation tests were carried out to assess horizontal coefficient of consolidation and initial stress in field. The ground consists of upper dredged fill and lower original clay layer having both similar marine clays. It should be, however, considered as multi-layered soft ground having different initial void ratio, initial water content, initial effective stress, and permeability and compressibility with directions. To assess initial stress of those soft layers in which have different stress history related to consolidation, CPTu test results, especially excess pore water pressure, were analyzed. It allows to find out distribution of excess pore water pressure and initial stress inner original clay layer.