• Title, Summary, Keyword: desiccation

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Desiccation Characteristics of Dredged Soft Clay by Ploughing Technique (교반기법에 의한 준설매립토의 증발촉진에 관한 연구)

  • 정하익;오인규;지성현;이승원;이영남
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.479-482
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    • 2002
  • The purpose of this paper is to present and discuss some of evaporation and desiccation observed in field experiments. Surface desiccation of dredged material is basically changed by evaporation characteristics which is controlled by weather and ploughing interval, etc. This study shows that ploughing interval is important factors in desiccation of dredged soft clay. A series of field experiments with variation of ploughing interval were carried out to get evaporation effiency and strength increase. In this study, it is proposed that ploughing technique on the total surface area expedites surface desiccation efficiency. Desiccation efficiency is improved when ploughing technique is applied on the surface area.

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Genetically modified carrot cells acquiring desiccation tolerance

  • Kamada, Hiroshi;Shiota, Hajime
    • Proceedings of the Botanical Society of Korea Conference
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    • pp.75-78
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    • 1999
  • To obtain direct evidence for thed involvement of C-AB13, a carrot (Daucus carota L.) homolog of VPI/Ab13, seed-specific transcription factor, in the acquisition of desiccation tolerance carrot non-embryogenic cells (NC) in which the C-AB13 gene was expressed ectopically was prepared. Non-transgenic NC, in which expression of C-AB13 was not detected, did not exhibit desiccation tolerance even after treatment with abscisic acid (ABA). In transgenic NC that expressed C-AB13, embryo-specific ABA-inducible genes (ECP genes) were expressed upon ABA-treatment. Furthermore, the transgenic NC became desiccation-tolerant upon ABA-treatment, but not tolerate desiccation without ABA-treatment. These results provide direct evidence for the involvement of C-AB13 in the ABA-induced acquisition of desiccation tolerance.

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Moisture Diffusion and Self-desiccation of Concrete at Early Ages (초기재령 콘크리트의 수분확산과 자체건조에 관한 연구)

  • 김진근;이칠성
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.303-308
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    • 1998
  • In the concrete structures exposed to environmental conditions at early ages, water movement occurs by moisture diffusion in the concrete, and self-desiccation of concrete is also occurred. Thus the internal relative humidity is changed from moisture diffusion and self-desiccation. Thus the internal relative humidity at each location in concrete includes the decrease by self-desiccation. Especially, for high-strength concrete the much unit cement content is used, so that the non-uniform relative humidity distribution is affected form self-desiccation at early ages. In this study, the internal relative humidity in concrete was measured at early ages, and the moisture diffusion component and self-desiccation component of total relative humidity were discussed.

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Desiccation Characteristics of Dredged Soft Clay by Large Model Test (모형토조시험을 통한 준설매립토의 건조특성에 관한 연구)

  • 정하익;오인규;지성현;이승원;이영남
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.591-596
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    • 2001
  • The purpose of this paper Is to present and discuss some of evaporation and desiccation observed in laboratory experiments under controlled conditions, and is to improve PTM(Progressive Trenching Method) operating technique. PTM is the technically feasible and economically justifiable dewatering and desiccation technique for dredged material containment areas. A series of laboratory experiments with large model test were carried out to get evaporation rate and strength increase. Surface desiccation of dredged material is basically changed by evaporation characteristics which is controlled by weather and trench type, etc. This study shows that trench depth and rain fall are important factors in desiccation of dredged soft clay.

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Effects of desiccation on the consolidation behavior of dredged and reclamated soil during period of reclamation (매립기간 중 건조효과가 준설매립토의 압밀거동에 미치는 영향)

  • Kim, Jin-Tae;Ahn, Jung-Seon;Yoo, Nam-Jae
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.515-520
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    • 2006
  • Yano method had been used in predicting the settlement of self-weight consolidation of dredged soil in the construction of reclamating the dredged soil. Its estimation was found to show some different results from field measurements. The numerical analysis with PSDDF was peformed find such differences, considering the effect of desiccation on the consolidation during the remaining time after reclamation. For the parametric study, numerical analyses with/without consideration of desiccation were carried out with changing the conditions of desiccation such as the number of placing the fill and the time period between each placement. As results of analysis, estimations about consolidation settlement and distribution of water contents with consideration of desiccation was in good agreements with field measurements. It was also found that the number of placing the fill and the time period between each placement did not affect the behavior of self-weight consolidation as much as the effect of desiccation.

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Differential Drying Shrinkage and Autogenous Shrinkage of Concrete at Early Ages (초기재령 콘크리트의 부등건조수축과 자기수축에 관한 연구)

  • 김진근;이칠성
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.309-314
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    • 1998
  • The moisture diffusion and self-desiccation cause the differential drying shrinkage and autogenous shrinkage at early ages, respecitvely. Thus total shrinkage strain includes the differential drying shrinkage and self-desiccation shrinkage. Thus in this study the shrinkage strain was measured at various positions in the exposed concrete and in the sealed concrete the self-desiccation shrinkage was measured. In low-strength concrete, the differential drying shrinkage increases very rapidly, but self-desiccation shrinkage is very small. But high-strength concrete shows the reverse result. And the analytical results for differential drying shrinkage were in good agreement with the test results.

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Behaviour of Consolidation in Dredged and Reclaimed Soil Considering the Effect of the Desiccation (건조효과를 고려한 준설매립토의 압밀거동)

  • Yoo, Nam-Jae;Park, Byung-Soo;Lee, Myung-woog;Lee, Joo-Won
    • 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.

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Evaporation and Desiccation of Soft Dredged Clay (초연약 준설토의 증발 및 건조특성 분석)

  • 정하익;오인규;지성현;이승원;이영남;김수삼
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.217-222
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    • 2000
  • An understanding of the behaviour of soft clay soils is important in a large number of civil engineering applications, including dredging operations, land reclamation and slurry management such as disposal and storage. Although the details of the behaviour depend on parameters such as the soil mineralogy, the pore water chemistry, the organic content and the microbiology, there are general features that are typical in many cases. The purpose of this paper is to present and discuss some of evaporation and desiccation observed in laboratory experiments under controlled conditions. Desiccation of dredged material is basically removal of water by evaporation which is controlled by weather and material type, etc. This study shows that (1) solar radiation, (2) wind velocity, (3) material depth, (4) trench depth are important factors in desiccation of dredged ultra soft clay.

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A Study on Characteristics of Strength Increase and Bearing Capacity in Dredged and Reclaimed Soil due to Desiccation Shrinkage (준설토의 건조수축에 의한 강도증가 특성과 지지력에 관한 연구)

  • Yoo, Nam-Jae;Lee, Jong-Ho;Lee, Myung-Woog;Kim, Hyun-Joo
    • Journal of Industrial Technology
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    • v.20 no.A
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    • pp.101-111
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    • 2000
  • This research is results of experimental and numerical works on characteristic of strength increase and bearing capacity in dredged and reclaimed soil due to desiccation shrinkage. For a soil sampled from southern coastal area in Korea, basic soil property tests and standard consolidation test with falling head permeability tests were carried out to obtain consolidational characteristics of soil. Double cone penetration test, laboratory vane test and unconfined compression test were also performed to investigate the change of shear strength with degree of desiccation. Model tests were performed in 1G environment and 30G level artificially accelerated condition by using the centrifuge model test facilities to investigate the bearing capacity of desiccated ground. Test results were analyzed by using the theoretical and load-settlement characteristics method proposed by Meyehof & Hanna(1978). On the other hands, the numerical technique, using the finite strain consolidation theory considering the effect of desiccation was used to estimate the appropriate time of using heavy construction equipments in field with respect to strength increase due to desiccation.

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Partial Desiccation of Embryogenic Calli Improves Plant Regeneration in Sugarcane (Saccharum Spp.)

  • Desai Neetin Shivajirao;Suprasanna Penna;Bapat Viswas Ananat
    • Journal of Plant Biotechnology
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    • v.6 no.4
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    • pp.229-233
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    • 2004
  • Partial desiccation of embryogenic calli cultures or somatic embryos leads to different physiological changes and maturation of somatic embryos, leading to improved plant regeneration. Embryogenic calli was induced from immature inflorescence segments and young leaf rolls of sugarcane (Saccharum officinarum hybrids CoC-671) on Murashige and Skoog's basal medium enriched with different concentrations of 2,4-D ($1-4\;\cal{mg/l}$), L-glutamine ($100\cal{mg/l}$), malt extract ($100\cal{mg/l}$), casein hydrolysate ($1000\;\cal{mg/l}$) and coconut milk ($5\%$) and solidified with $0.2\%$ gel rite. The embryogenic calli were subjected to desiccation for 1-8 h. Desiccation of the calli for 6-7 h resulted in enhancement of plant regeneration frequency ($83-96\%$) as compared to control ($12\%$). Plantlets exhibited vigorous growth to maturity in the greenhouse. Partial desiccation of embryogenic calli offers as a simple method for improving plant regeneration frequency in sugarcane.