• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.441-448
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• 1999

The load distribution in a ground anchor is very complex because it involves three different materials(soil, grout, and steel), which sometimes act as composite sections (bonded length) or separately (unbounded length). Therefore it is very hard to understand load transfer mechanism on the anchor. In order to understand the load transfer, it is essential to consider the load distribution In the three different materials. On these purposes, full scale anchor test is planned on the geotechnical site at Sunkyunkwan University Prior to the test, modeling and analyses of the load transfer mechanism were performed on the data from the case histories.

• Journal of Radiation Protection and Research
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• v.16 no.2
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• pp.55-65
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• 1991

Soil-to-plant transfer coefficients of Mn-54, Co-60, Zn-65, and Cs-137 were estimated for the edible parts of the rice, soybean, lettuce, carrot, and squash grown in different soils by radiotracer uptake experiments using pot cultures. The transfer coefficients of radionuclides were in the order of Zn-65 > Mn-54 > Cs-137 > Co-60 in most of the cases studied. The coefficients for soybean were roughly an order of magnitude higher than those for rice. Among vegetables, lettuce mostly showed the highest value and squash, the lowest. In the strongly acidic soils, transfer coefficients were much higher than in the moderately acidic soils. From the data obtained. crop-specific transfer coefficients of the four nuclides were proposed for the use in Korean food-chain radiation dose assessment.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.6
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• pp.1042-1047
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• 2011

Copper and Zinc are essential trace elements for all living organisms. When presenting in excess amount in soils, however they can be toxic to plants. In order to examine the transfer of Cu and Zn from soils to plants and to predict their contents in plants using soil factors, we investigated total and mobile contents of Cu and Zn in soils and their uptake by lettuce (Lactuca sativa L.) in plastic film houses. Total Cu and Zn contents in soils were $17.5{\sim}65.9mg\;kg^{-1}$ (mean: $39.3mg\;kg^{-1}$) and $63.2{\sim}200mg\;kg^{-1}$ (mean: $137mg\;kg^{-1}$), respectively. Mobile Cu and Zn contents in soils were $(0.04){\sim}0.55mg\;kg^{-1}$ (mean: $0.18mg\;kg^{-1}$) and $(0.05){\sim}2.62mg\;kg^{-1}$ (mean: $0.47mg\;kg^{-1}$), respectively. Soil pH ranged from 5.4 to 7.3 and OM from 24.1 to $59.9g\;kg^{-1}$. Mean Cu contents in leaves and roots of lettuce were 9.20 and $17.2mg\;kg^{-1}$, respectively which showed that Cu was accumulated mainly in root parts of lettuce and not easily transported to leaves. In contrast, Zn was fairly evenly distributed in leaves and roots with mean values of 54.5 and $56.7mg\;kg^{-1}$, indicating relative high mobility of Zn in lettuce. Transfer factors of Cu and Zn from soil total contents to roots and leaves of lettuce ($TFS_tR$ and $TFS_tL$) were between 0.1 and 1, while transfer factors from soil mobile contents to roots and leaves ($TFS_mR$ and $TFS_mL$) were between 10 and 1000. Transfer factors of Zn were higher than those of Cu, showing Zn was more easily absorbed by plants than Cu. Cu and Zn uptake was stronger influenced by soil pH and mobile contents than total contents and OM and could be significantly described by multiple regression equations including soil pH and soil mobile contents as variables.

• Journal of the Korean Geotechnical Society
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• v.24 no.11
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• pp.61-70
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• 2008

Load settlement behaviors and load transfer characteristics of rock-socketed pile subjected bi-directional load at pile tip were investigated using bi-directional pile load tests (BD PLT) performed on ten large-diameter drilled shafts at four sites. Based on test results, additional pile-toe displacement ($w_{bs}$) by coupled soil resistance was analyzed, and thus equivalent top loaded load-settlement curve of pile subjected bi-directional load was proposed by taking into account the coupled soil resistance. Through comparisons with field case studies, it is found that for test piles there exists effect of coupled soil resistance, which is represented by wbs, and thus an equivalent curve obtained by existing uncoupled methods can overestimate bearing capacity of piles by BD PLT. On the other hand, the analysis by the proposed method with soil coupling effect has a considerably larger settlement when compared with the results by uncoupled load transfer method and estimates reasonable load-settlement behaviors of test piles. In case of pile socketed in high strength rocks, however, effects of coupled soil resistance can be neglected.

• Journal of Soil and Groundwater Environment
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• v.21 no.6
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• pp.146-155
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• 2016

The field feasibility tests for a phytoextraction process were performed to identify the effect of citric acid as a chelate on the uranium (U) transfer into the plant for the naturally U contaminated soil in Duckpyeongri, Korea. For the feasibility tests, lettuce and Chinese cabbage were cultivated for 49 days on four testing grounds ($1m{\times}1m{\times}0.5m$ in each) in 2016. The citric acid solution was added to two testing grounds (one for lettuce and the other for Chinese cabbage) increasing the U transfer in two crop plants and their results were compared to those without the citric acid solution. When without the citric acid solution, the U concentration of plant after the cultivation was low (< $45{\mu}g/kg$ for leaves and < $450{\mu}g/kg$ for roots). However, with the addition of 50 mM citric acid solution, the U concentration of lettuce leaves and roots increased by 24 times and 1.8 times, and the U concentration of Chinese cabbage leaves and roots increased by 86.7 times and 5.4 times. The absolute accumulated U amount (${\mu}g$) in lettuce and Chinese cabbage also increased by 8.7 times and 50 times, compared to those without citric acid solution. Less than 8% of the U amount of exchangeable/carbonate phases was removed by using the lettuce and Chinese cabbage when the citric acid solution was not applied. However 52% and 66% of the U amount in exchangeable/carbonate phases were removed by the lettuce and the Chinese cabbage when the citric acid solution was added. The effect of the citric acid on the U transfer capability into the plants was quantitatively investigated by the field feasibility test, suggesting that U existing as exchangeable/carbonate phase in soil can be successfully removed by the phytoextraction process using Chinese cabbage with citric acid.

• Journal of the Korean Geotechnical Society
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• v.20 no.2
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• pp.59-66
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• 2004

Sand compaction pile (SCP)-improved ground is composite soil which consists of the SCP and the surrounding soft soil. When a surcharge load is applied to composite ground, time-dependent behaviors occur in the composite soil due to consolidation according to radial flow toward the SCP. In addition, stress transfer also takes place between the SCP and the soft soil. This paper presents the numerical results of cylindrical composite ground that was conducted to investigate smear effect on consolidation behaviors of SCP-improved ground. The results showed that the smeared zone of soft clay had a significant effect on effective stress-pore water pressure response, stress transfer mechanism and stress concentration ratio of composite ground. Amount of stress transfer between the clay and the SCP was maximum in depth of z/H=0.25, and decreased with depth. Stress concentration ratio of composite ground was not constant, but depended on consolidation process. It was also found that the value of stress concentration ratio in soft clay with smeared zone was larger than that in soft clay without smeared zone.

• Journal of the Korean Geotechnical Society
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• v.23 no.11
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• pp.49-58
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• 2007

Numerical experiments using a distinct element code (PFC3D) were carried out for the analysis of grout-material transfer in soil layers and also for the analysis of increase in mechanical strength after permeation grouting. For rapid analysis, up-scaling analysis in length scale was adopted, and the following observations were made from the numerical experiments. Firstly, the relative size of grout material with respect to the in situ soil particles controlled the transfer distance of the grout particles. When the size of grout particle was 0.2 to 0.25 times of the in situ soil particles, clogging of pore spaces among the in situ soil particles occurred, resulting in restricted propagation of grout particles. It was also found that there was a threshold value in the size of grout particle. Below the threshold value, the transfer distance of the grout particle did not increase with the decrease of particle size of the grout material. Secondly, the increase in cohesion and internal friction angle was observed in the numerical specimen with grouting treatment, but not with the untreated specimen.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.2-11
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• 2006

In the processes of hydrological cycle, when precipitation reaches the ground surface, water may become surface runoff or infiltrate into soil and then possibly further percolate into groundwater aquifer. A part of the water is returned to the atmosphere through evaporation and transpiration. Soil moisture dynamics driven climate fluctuations plays a key role in the simulation of water transfer among ground surface, unsaturated zone and aquifer. In this study, a one-layer canopy and a four-layer soil representation is used for a coupled soil-vegetation modeling scheme. A non-zero hydraulic diffusivity between the deepest soil layer modeled and groundwater table is used to couple the numerical equations of soil moisture and groundwater dynamics. Simulation of runoff generation is based on the mechanism of both infiltration excess overland flow and saturation overland flow nested in a numerical model of soil moisture dynamics. Thus, a comprehensive hydrological model integrating canopy, soil zone and aquifer has been developed to evaluate water resources in the plain region of Huaihe River basin in East China and simulate water transfer among precipitation, surface water, soil moisture and groundwater. The newly developed model is capable of calculating hydrological components of surface runoff, evapotranpiration from soil and aquifer, and groundwater recharge from precipitation and discharge into rivers. Regional parameterization is made by using two approaches. One is to determine most parameters representing specific physical values on the basis of characterization of soil properties in unsaturated zone and aquifer, and vegetations. The other is to calibrate the remaining few parameters on the basis of comparison between measured and simulated streamflow and groundwater tables. The integrated modeling system was successfully used in the Linhuanji catchment of Huaihe plain region. Study results demonstrate that (1) on the average 14.2% of precipitation becomes surface runoff and baseflow during a ten-year period from 1986 to 1995 and this figure fluctuates between only 3.0% in drought years of 1986, 1988, 1993 and 1994 to 24.0% in wet year of 1991; (2) groundwater directly deriving from precipitation recharge is about 15.0% t of the precipitation amount, and (3) about half of the groundwater recharge flows into rivers and loses through evaporation.

• Journal of the Korean Geotechnical Society
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• v.32 no.6
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• pp.5-16
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• 2016

In the geosynthetics-reinforced piled embankment the effects of soft soil stiffness, friction angle of the fill material, tensile stiffness of geosynthetics, and height of the embankment on the load transfer soil arch measured by the critical height were numerically investigated. Results from parametric studies show that the magnitude of the soft soil stiffness is the most influencing factor on the critical height. The contour charts of the critical height with respect to the combination of the soft soil stiffness and other parameters were presented. The charts show that the critical height sensitively varies with the combination of the soft soil stiffness and the height of embankment. Under the sufficiently low stiffness of soft soil, the critical height sensitively varies with the friction angle of the fill material. Once the geosynthetic layer is placed, however, the magnitude of the tensile stiffness of the geosynthetic layer hardly influences the critical height of the soil arch.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.20-27
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• 2004

Reinforced twice than width of foundation with SIC under steel piles drived in cohesion soil and in the coal-limestone which heavily fractured. To analyze behaviour characteristic of steel piles, load transfer test was performed to steel piles attached with strain gauges to axial direction. After it passed 49days, dynamic load test was performed to set-up effect of steel piles bearing capacity. The results of test were compared to each other. According to the results, as the skin friction of steel pile was on the same condition, end bearing capacity of steel piles established on SIC solid of cemented milk in cohesion soil was three times than steel piles established on SIG solid of cemented milk in heavily fractured coal- limestone. After piles were driven and passes 49days, in case of piles on SIG solid of comented milk in cohesion soil the increaes of allowable bearing capacity was 442.9% and allowable bearing capacity of piles on SIG solid of cemented milk in heavily fractured coal-limestone increased 22.4%.