• Journal of the Korean Society of Environmental Restoration Technology
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• v.9 no.6
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• pp.38-51
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• 2006

This study was carried out to improve rehabilitation effect by hydro-seeding methods on denuded slopes. Lespedeza cyrtobotrya, Indigofera pseudotinctoria, Arudinella hirta, Poa pratensis, and Lolium perenne were used in this study. The results of the germination and growth characteristics by seed coating, slope control and soil mulching treatments are summarized here. Seed coating of those plants had an effect on germination ratio, germination force, $LD_{50}$, and seedling growth of stem, leaf and root. The seed coating effect was highest for I. pseudotinctoria while the seedling growth was best for L. cyrtobotrya. Vermiculite+Talcum was the best coating material for germination and seedling growth of the plants. As the slopes were steeper, germination ratio was lower and seedling growth of stem and root decreased. Lots of seeds and soils were swept away when the slope was steep. Soil mulching was effective for germination, seedling growth of stem and root, and soil stabilization. It was more effective when the slope was steeper. Coir net was the most effective soil mulching material n this study.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.811-818
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• 2005

Stability analyses on the 17 railroad cut-off soil slopes were carried out. The influences of rainfall infiltration on the slope stabilities were taken into account by seepage analyses using finite element method and by assuming ground water tables to be located adjacent to soil surface. The validity of those analyses were evaluated by comparing the slope failure characteristics between analysis results and the past failure records. The analyses were not appropriate to estimate the failure surface and the method considering only the increase of pore-water pressure (reduction of matric suction) as the influence of rainfall cannot appropriately estimate the surficial failures that occurred most of the cut-off soil slopes. For the better estimation of the surficial failure, the influence of water flows over slope surface which erode soil mass and/or increase driving force, should be evaluated and considered.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.724-731
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• 2006

The purpose of this study is to estimate a landslide using the SLOPILE program from the slope reinforced by slope stability systems such as soil nailing and pile. To do this, cutting slope located at Donghae-Highway in Kwangwon-Do was considered. The behavior of slope was monitored for a long term by using instrumentation according to the reinforcement stages. The sequence of reinforcement stages was followed as pile installation, boring, soil nailing installation, anchoring and embankment. The result from this case study shows that the safety factor of slope depends on the reinforcement stage more or less.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.9 no.6
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• pp.133-142
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• 2006

Occasionlly, a lot of plants withered on the marine upheaval soil, because of the potential acid sulfate soil. It was necessary to investigate the chemistry of soil, before planting on Ulsan-Jungjadong cut-slope of road construction site. Cut-slope surface soils were sampled on the every varying points in soil colour and analyzed chemically. Germination status of seeds in sample soils was investigated such as Albizzia julibrissin, Festuca arundinacea. Relationship between germination status and chemistry of soil was analyzed. The results of investigation and analysis are as follows. 1. Germination of seeds was inhibited, less than pH($H_2O$ 1 : 5) 2.63. 2. Germination of seeds was inhibited, more than EC($H_2O_2$ 1 : 5) 13.4mS. 3. Germination of seeds was inhibited, more than aluminum ion content 2.0ppm in soil solution extracted by A$H_2O$ and 6.2ppm by $H_2O_2$. 4. pH($H_2O$ 1 : 5), EC($H_2O_2$ 1 : 5) and aluminum ion content proved chemical indicators of seed germination inhibition, in case of potential acid sulfate soil.

• Journal of the Korean Geotechnical Society
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• v.35 no.12
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• pp.45-58
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• 2019

In this study, a stochastic analysis procedure based on numerical analysis was proposed to evaluate a kind of intensity-duration rainfall threshold for the initiation of slope failure due to rainfall infiltration. Fragility curves were generated as a function of rainfall intensity-duration from the results of probabilistic slope stability analysis by MCS considering the uncertainty of the soil shear strength, reflecting the results of infiltration analysis of rainfall over time. In the probabilistic analysis, slope stability analyses combined with the infiltration analysis of rainfall were performed to calculate the limit state function. Using the derived fragility curves, a chart showing the relationship between rainfall intensity and slope failure-time was developed. It is based on a probabilistic analysis considering the uncertainty of the soil properties. The proposed probabilistic failure distribution analysis could be beneficial for analyzing the time-dependent failure process of soil slopes due to rainfall infiltration, and for predicting when the slope failure should occur.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.3
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• pp.449-456
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• 2018

In this study, a soil nail design method for a stability analysis of local instability with nail reinforced slope was proposed. The failure mechanism of a local instability of slope was studied and a theoretical equation to estimate the stability of slope was developed. Using the developed equation, the stability analysis was performed according to installation conditions of soil nail such as a slope inclination, a thickness of soil layer, a nail inclination, and a nail spacing. Considering those design factors, a sensitivity analysis for each influence factors was conducted. Analysis results showed that the safety factor of reinforced slope with nail was higher than the slope without nail. In addition, the safety factor of slope according to ground condition was increased in the order of dry, saturated, and seepage condition.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.30 no.5
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• pp.207-216
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• 2018

This research compared and analyzed safety ratio of slope with Talren97 and SoilWorks based on limit equilibrium analysis and Midas GTS based on finite element analysis. For the analysis variables, there are slope height, berm condition, soil parameter, groundwater level, slope inclination. All of slope stability analysis were performed by dividing into dry season and rainy season. As the result of the analysis of Talren97 and SoilWorks based on same theory, safety ratio of slope shows same value, so there was no difference between the programs. In comparison with limit equilibrium analysis, the result of finite element analysis showed somewhat high ratio of safety and it was higher by about 2.4% averagely. The difference between the result of limit equilibrium analysis and that of finite element analysis is in the range which can ignored in practical work.

• Journal of the Korean Geosynthetics Society
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• v.12 no.2
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• pp.67-74
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• 2013

In this study, the prediction of slope hazard probability was performed to the study area located in Hadae-ri, Woochun-myeon, Hoengsung-gun, Gangwon Province around Youngdong express way using the computer program SHAPP ver 1.0 developed by a decision tree model. The soil samples were collected at total 10 points, and soil tests were performed to measure soil properties. The thematic maps of soil properties such as coefficient of permeability and void ratio were made on the basis of soil test results. The slope angle analysis of topography was performed using a digital map. As the prediction result of slope hazard probability, 2,120 cells among total 27,776 cells were predicted to be in the event of slope hazards. Therefore, the predicted area of occurring slope hazards may be $53,000m^2$ because the analyzed cell size was $5m{\times}5m$.

• Asian Journal of Turfgrass Science
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• v.11 no.2
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• pp.89-95
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• 1997

Soil chemical properties were investigated to elucidate vertical movement of mineral nutrients in a fairway slope of 27 year-old golf course. Soil samples were taken at every 10cm depth to 4Ocm on 4 sites 20m apart each along two parallel lines 60m apart on the slope(15˚) in August. Accord-ing to the similarity of vertical distribution pattern they could be classified into 6 distinctive groups(magnesium, nitrate, phosphorus, ammonium, manganese and copper) and the slope tended to affect the vertical movement of minerals. The contents of Ca and Mg increased with depth while NO$_3$-N and Zn decreased and correlated positively. Soil pH showed significant positive correlation with depth, Ca and Mg. Phosphorus content was highest in 10~20cm depth and decreased resulting in relatively high content in 30~40cm depth of the bottom site of slope. Iron distribution pattern was similar to phosphorus. Potassium and $NH_4$showed various(irregular) patterns. Mn was highest in the deep layer at the lower sites of slope but it was reverse at the upper sites and negatively correlated with Fe. Cu content incresed with depth and heighest in 20~30cm depth. Electroconductivity showed significant positive correlation with $NO_3$-N. Magnesium, cal-cium and copper seem to be prone to defficiency due to fast leaching, and nitrate and phosphorus prone to excess problem. Preventive measures on acidification of surface soil should be taken.

• Journal of the Korean Geosynthetics Society
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• v.7 no.4
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• pp.9-18
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• 2008

Shallow slope failures in residual soil during periods of prolonged infiltration are common in Korea. This study examines an infinite slope analysis to estimate the influence of infiltration on surficial stability of slopes by the limit equilibrium method. Approximate method which is based on the Green-Ampt model have been considered to evaluate the likelihood of shallow slope failure which is induced by a particular rainfall event that accounts for the rainfall intensity and duration for various return periods. Pradel & Raad method which is devised to predict the depth of wetting front to decomposed granite soil slopes having measured soil-water characteristic curves. To compare the results with those obtained from the Pradel & Raad method, a series of numerical analysis using SEEP/W were carried out. It was found that the stability analysis of unsaturated soils calculated by using the soil-water characteristic curve of decomposed granite soils was found to be a proper analysis for shallow slope failures due to rainfall.