• 기술발표회
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• s.2006
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• pp.135-145
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• 2006

Soil nailing systems are generally many used in underground excavations and reinforcements of slopes since the first construction as a temporary retaining wall in 1993, Korea. In recently, they are many attempts to expand the permanent reinforcements of slopes However, experimental studies related to soil nailing systems are insufficient Specially, there are no researches related in the large scaled load tests of soil nailed walls in Korea In this study, a case study on the large scaled load tests of soil nailed walls is introduced and the behavior characteristic of them is investigated Also, they are proposed allowable deformation corresponding to the serviceability limit of soil nail walls and ultimate deformation corresponding to the collapse state of the walls. These results can be applied to the maintenance management of soil nailed walls And analysis on the required minimum factor of safety of soil nailed walls using the relation curve of load ratio and deformation ratio are carried out

• Journal of Korea Water Resources Association
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• v.41 no.6
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• pp.565-574
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• 2008

Fire-enhanced soil hydrophobicity often increases runoff and erosion in the mountain hillslope following severe wildfires. Estimation techniques for WEPP's parameters were studied in burnt mountain slopes. In burnt mountain slopes, the model over-predicted runoff in the small runoff and under-predicted runoff in the great runoff, and in the lower sediment runoff it had a tendency to over-predict soil loss. The effective hydraulic conductivity was most sensitive in the WEPP's runoff and its sediment runoff was mainly effected by the effective hydraulic conductivity, initial saturation, rill erodibility, and interrill erodibility. To improve the applicability of the WEPP, the adjustment coefficient of effective hydraulic conductivity was defined for runoff and the adjustment coefficient of rill erodibility and interrill erodibility was presented for sediment runoff. The adjustment coefficient of effective hydraulic conductivity in wildfire mountain slopes increased with maximum rainfall intensity of single storm and the vegetation height index. The adjustment coefficients of rill erodibility depended on soil components of size distribution curve and total rainfall depths in single storm. The adjustment coefficients of interrill erodibility decreased with increases of maximum rainfall intensity and vegetation height index. These results may be used in the application of WEPP model for wildfire mountain slopes.

• The Journal of Engineering Geology
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• v.15 no.1
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• pp.57-66
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• 2005

The failure of cut slope and landslide sometimes come from a local downpour within a short duration in Korea. Especially, most of recent downpour converged upon a limited region and seemed the characteristics of guerilla. Characteristics of slopes failed due to local downpour are analyzed. failure mode is also analyzed with respect to the depth of soil layers and the change of groundwater level. To blow the influence factors of the slope stability during local downpour, the authors conducted field survey for failed slopes and tried to make a comparative study of 1,372 cut slope data distributed in the national road. FLAC-SLOPE(ITASCA Co.) is used to analyze slope stability with changing depth of soil layers and groundwater level. The result shows that the failed types of domestic slopes during local downpour are mainly shallow collapse and landslide. The change of soil depth and groundwater level have influenced on the stability of slopes.

• The Korean Journal of Ecology
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• v.8 no.2
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• pp.81-87
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• 1985

The vegetation on the north and south slopes of Kwanak mountain was assessed and recorded during thesummer of 1976. Recordings were made of 5*5m quadrats placed along the transects running parallel to the slopes. On the north slope, most of large trees such as Alnus sibirica, Sorbus alnifolia, Robinia pseudo-acacia and Pinus rigida make the crown and their mean DBH was conspicuously large, while the vegetation of south slope is dominated by dwarf Juniperus utilis, Pinus densiflora, Weigela florida var. glabra which are considered as a resistant species of dry site. The amount of humus, total nitrogen, soil water content and available phosphorous is higher on the north slope than the south one. However, the soil pH is higher on the south slope. It is assumed that the humus content is a main factor to make difference on the type of vegetation between the north and south slope.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.210-220
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• 2005

We have analyzed the stability for cut-slopes at main street 3-2 line section in Pa-ju local industrial complex. After studying an additional boring test, laboratory test and face mapping etc., we have determined the extent of reinforcement, slope inclinations and soil strength parameter from the analysis of test results. After changing the inclination of slopes for ground limit and carrying out the analysis of slope stability, we applied the Mass Nailing Method to the site because of need for reinforcement to soil and weathered rock slopes. In slope for soft and hard rock sections, we also reinforced the sections that are difficult to obtain the safety without reinforcement in alteration zone.

• Journal of the Korean Geotechnical Society
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• v.17 no.6
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• pp.123-133
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• 2001

Since most of soil slopes are in an unsaturated state, it is necessary to consider the unsaturated characteristics of soil slopes, in order to obtain more reasonable results. Therefore in this study we supplemented a slope stability analysis program to consider them, based on the concept of limit equilibrium. We also applied an optimization technique to search for a failure surface. Besides, we carried out experiments to obtain the unsaturated soil properties required in the analysis with weathered granite soils. We formulated a nonlinear apparent cohesion relationship with the matrix suction to be able to apply the unsaturated shear strength characteristics to the stability analysis. In addition, we intended to obtain more accurate soil water characteristic curves(SWCC) by measuring the change in volume of the specimen in the SWCC tests. As a result, we could appropriately assess the change of the safety factor according to the rainfall intensity and duration, by considering the variation of suction, permeability, and shear strength caused by the infiltration of rainfall into slopes.

• Journal of Environmental Science International
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• v.12 no.2
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• pp.93-100
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• 2003

In most mountainous parts of the temperate zone of Japan along the Pacific Ocean, some climatic climax forests, whose main dominant species is Fagus crenate, F. japonica or Quercus mongolica var. grosseserrata, are distributed. In the riparian regions of the zone, however, there appear summer green forests composed of the different species from the climatic climax forests. Climate plays an important role in determining the overall distribution of vegetation, but some environmental factors, i.e., topography, soil type, soil moisture content, etc. have a great influence on vegetation formation. Riparian forests seem to be controlled by various geomorphologic disturbances, such as landslide, soil erosion and accumulation. The study aims to present the relationships among vegetation, soils and landforms in the process of determining riparian forests dominated by Fraxinus platypoda and Pterocarya rhoifolia establishment in the mountainous region of central Japan. The study area extends an area of 302 ha with a range of elevation between 925 m and 1,681 m at the Chichibu mountains. The landforms were corditied at sampling grids (25 $\times$ 25 m, n = 4,843) using a hierarchical system, and a brief description of the forest soil classification was also given. The mutual relationship analysis indicated that forest soils and landforms play a significant role in determining the geomorphological process of riparian forest, and shaping the ultimate pattern of vegetation. At the study area, riparian forests were mainly found on the $B_E$ forest soil type and steep slopes ( > 30$^{\circ}$) at convex slopes along the streams. On the other hand, the direction of slopes did not have a significant impact on the establishment of the riparian forests. A mosaic of patchy distribution of those riparian forests on the slightly wetter $B_E$ forest soil type was one of the characteristic features of the study area. This particular soil which contained large talus gravels was found on the land formed by erosion and deposition of landslide.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.13 no.5
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• pp.81-89
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• 2010

This study was conducted to evaluate the effects of early revegetation by analyzing the characteristics of germination and growth of Chrysanthemum zawadskii using vegetation-plant in rock slopes. After making up a growing basis of approximately 20-cm depth and 10-cm diameter by using a boring machine, the surface of rock slopes was planted with vegetation-plant. The number of germinating populations by soil media was 41 in H.s, 4 in T.s, 3 in M.s, and 0 in M.g.s. The germination rate (%) by soil media was 20.0% in H.s, 3.3% in T.s, 2.5% in M.s and 0% in M.g.s. In monthly changes of growth rate, the aspect was northwest direction, the soil media was H.s, and the treatment was microorganism plot. The main factors affecting survivorship and growth of population were soil media and treatment plot. The interaction between each factor had a good effects in bearing x treatment plot, soil media x treatment plot. but, it is recommended that the mulching of vegetation plant is highly needed to help the germination of seed and growth of vegetation because of loss of seed and soil media occurred due to rainfall. Therefore, The result suggests that the revegetation technique using boring in rock slope was very efficient in respect of the early revegetation and the landscape.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.670-675
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• 2006

The purpose of this study is the infiltration characteristics of soil cut-slope by the repetition & concentration rainfall. The maximum rainfall concentrate from June until September which is a rainy season in our country Stability analysis of soil cut-slopes has been conducted by limit equilibrium method on Seep/w and finite element method on Slope/w.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.93-101
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• 2005

The formation of slopes is unavoidable under the special circumstance of Korea where $7%$ of the whole area are composed of mountains and civil engineering projects such as road and site developments are increasing with industrial development and horizontal expansions of urban area. Stability of slopes is one of quite important issues under special meteorological characteristics that over two-thirds of annual average rainfall is concentrated in summer season and the localized torrential downpour is getting more frequent recently. As a result of these circumstances, partial slope failures by debris flow of the high water content soils occur frequently in cut soil slopes. In this case of debris flow slope failure, slope declination method is selected fur the stable recovery because it is impossible to recover entirely by existing recovery methods. Seeding or special grass planting methods are followed separately without exception. The method by which entire recover with bigger stability ratio would be possible and grass planting work would be done simultaneously is developed. For debris flow failure slopes, this study secured the safety of slopes by preventing the inflow of rainwater and scour using geosynthetics-reinforced embankment, and created nature-friendly slopes by planting trees on the slopes.