• Korean Journal of Environment and Ecology
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• v.20 no.4
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• pp.415-424
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• 2006

This study was carried out to analyze the characteristics of forest watershed factors by using the quantification theory(I) for evaluation and prediction of the failure hazard area. Present $sediment(m^3/yr/ha)$ of erosion control dams were investigated in 95 sites of erosion control dam constructed during 1986 to 1999 in Gyeongnam province. The results obtained from this study were summarized as follows; General condition of class I(Very hazard area) were as follow; Igneous rock in parent rock, coniferous in forest type, below 20year in stand age, below 30cm in soil depth, SCL in soil texture, $31{\sim}40%$ in gravel contents, $S{\sim}E$ in aspect, $2,501{\sim}3,600m$ in length of main stream, $26{\sim}30$ in number of total streams, $6,601{\sim}10,000m$ in length of total streams, over 3 in stream order, over 16 in number of first streams order and over $31^{\circ}$ of slope gradient. General condition of class IIl(hazard area) were as follow; Metamorphic rock in parent rock, hardwood in forest type, over $21{\sim}24year$ in stand age, $31{\sim}40cm$ in soil depth, SiCL or SCL in soil texture, $11{\sim}20%$ in gravel contents, $S{\sim}W$ in aspect, $1,501{\sim}2,600m$ in length of main stream, $6{\sim}10$ in number of total streams, $3,501{\sim}5,500m$ in length of total streams, 2 in stream order, $6{\sim}10$ in number of first streams order and over $31^{\circ}$ of slope gradient. General condition of class III(Un hazard area) were as follow; Sedimentary rock in parent rock, mixed in forest type, over 25year in stand age, $41{\sim}50cm$ in soil depth, SiCL in soil texture, below 10% in gravel contents, $N{\sim}W$ in aspect, below 500m in length of main stream, below 5 in number of total streams, below 1,000m in length of total treams, below 1 in stream order, below 2 in number of first streams order and below $25^{\circ}$ of slope gradient. The prediction method of suitable for failure hazard area divided into class I, II, and III for the convenience of use. The score of class I evaluated as a very hazard area was over 4.8052. A score of class II was 4.8051 to 2.5602, it was evaluated as a hazard area, and class III was below 2.5601, it was evaluated as a un hazard area.

• Journal of the Korean Geosynthetics Society
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• v.14 no.4
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• pp.117-127
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• 2015

Recently, there has been a string of negligent accidents for the retaining wall and slope. In order to measure the ground deformation for the MSE wall, the authors carried out the model test to assess behavioral characteristics of geogrid MSE walls in active failure state with different conditions of geogrid reinforcement. The models are built in the soil container box having dimension, 100 cm long, 90 cm height, and 10 cm wide. The reinforcement used in the model test is geogrid (polyvinyl chloride, PVC). Three geogrids are sized by $30cm{\times}60cm$, $30cm{\times}70cm$, $30cm{\times}80cm$ (width ${\times}$ length) respectively. In this study, the laboratory model tests represented for several conditions of the MSE wall, and then its results were compared to 2D FE analysis.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.947-954
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• 2008

Waste landfills built on weak soils have the possibilities of the failure of slope and foundation due to the disposed waste loads. To ensure the landfill will sustain its stability within a limited site area, it's necessary to investigate and understand the characteristics of soft land by identifying the requirements for waste filling and by quantitative field measurement and management of landfills. In this paper, the stability analyses are performed using the field measurement data of Gimpo #2 Metropolitan Landfil. For the stability analysis, Tominaga-Hashimoto method and Kuriharh method, which may be able to manage the stability of the landfill quantitatively, are used.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.877-882
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• 2010

This paper is a result of investigating causes and main characteristics of landslides, occurred at Hongcheon area in Gangwondo during July in 2006, by collecting relevant data and visiting site. The main cause of landslides in this area has been found to be saturation of the ground wetted by a series of precipitations during 10~13 July and the heavy rainfall during 15 July. The pattern of the landslides could be classified as translational failure, occurred at the boundary between the relatively thin weathered residual soil and the mother rock. By analyzing a number of failed slopes based on site visit and reviewing collected data, typical widths of failed slopes are in the range of 10~20m (minimum: 5m, maximum: 70m). Lengths of landslide area are in the wide range of 10~450m. Most of area are less than 20m in width and 100m in length so that their shapes are long and narrow, frequently observed in Korea, and their areas are relatively small size of around $1000m^2$. The inclinations of the failed slopes are in the range of $10{\sim}60^{\circ}$ while the most probable slope angle is about $20{\sim}25^{\circ}$.

• Journal of the Korean GEO-environmental Society
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• v.19 no.4
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• pp.17-26
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• 2018

This study systematically examines the changes in the compressive and tensile strength of soil cement reinforced by natural hair fiber, which is regularly produced from human. Extensive experimental tests of various test specimens have been carried out in a laboratory. Several factors are considered, including the soil type, amount of cement, amount of fiber, fiber length, loading type, and curing age. The test results indicate that both the compressive and tensile strengths are significantly affected by the fiber, either increasing or decreasing depending on the conditions. The increase in tensile strength is significant in the sand-based soil cement due to the tensile resistance of the fiber which is interlocked with the surrounding soil or cement particles. The natural fiber provides a larger strain to failure due to its extensibility, which allows greater deformation. Based on the test results, natural hair fibers can be an effective and environmentally friendly way to improve soil ground subjected to tensile loading, such as an embankment slope, road subgrade, or landfill, thus reducing the cost for cement and waste treatment. The study results provide a useful information of better understanding the mechanical behavior of natural hair fiber in soil cement and the practical use of waste materials in civil engineering. The findings can be practically applied for improving earth structures under tensile loading.

• Journal of the Korean Geotechnical Society
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• v.21 no.2
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• pp.145-150
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• 2005

It is useful to select an appropriate mathematical model to predict landslide. Through observation and analysis of real-time measured time series, a reasonable mathematic model is chosen to do prediction of landslide. Two theoretical models, such as polynomial function and growth model, are suggested for the description and analysis of measured defermation from an active landslides. These models are applied herein to describe the main characteristics of defermation process for two types of landslide, namely polynomial and growth models. The TRS (tensiof rotation and settlement) sensors are applied to adopt two models, and the data analysis of two field (Neurpjae and Buksil) resulted in good coincidence between measured data and models.

• Journal of the Society of Disaster Information
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• v.16 no.3
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• pp.577-585
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• 2020

Purpose: The presence of the matric suction in unsaturated soil increases the stability of the slope, but the reduction of the matric suction due to precipitation can cause sudden slope failure, resulting in a major disaster. In this paper, engineering characteristics in unsaturated state were analyzed for granite weathering soil, which is the representative mountain soil of Korea. Method: Experiments and analysis were conducted on granulated weathering soil as unsaturated shear strength relationships for moisture characteristic curves, unsaturated injection curves, and matric suction under unsaturated conditions. Result: It was analyzed that a rapid change in the matric suction for volumetric water content occurs compared to the case where the particle size distribution is poor and the particle size distribution is good. A good case for the particle size distribution indicates a relatively small permeability coefficient at the same matric suction capacity compared to a poor case. The greater thematric suction, the greater the shear strength. Conclusion: For Korea's representative soil, granulated weathering soil, the functional characteristic curves, unsaturated permeability coefficients, unsaturated shear strength, etc., which are engineering characteristics in unsaturated state, were tested to secure each correlation.

• The Journal of Engineering Geology
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• v.14 no.4 s.41
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• pp.487-498
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• 2004

There is an increasing trend of construction works in mountainous areas by the urban development in Busan that is mainly composed of mountains. The study area, Hwangryeong Mt., is one of developing sites in the urban area, too. Landslides and cut-slope failures that occur large damages of human beings and the properties are influenced by soil characteristics as well as rock properties. This study analyzed geotechnical characteristics of soil dependent on geology at Hwangryeong Mt. where a large slope failure had been occurred in 1999. Geology of the study area is composed of the Cretaceous sedimentary rocks and volcanic rocks. Soil layer of the slopes can be grouped into sand mixed with clay and silt. The cohesion is plotted between $0.001\;and\;0.066kg/cm^2$. The friction angles are distributed in the ranges between $32^{\circ}\;and\;39^{\circ}$, meaning soil bearing a high friction angle. The permeability coefficients are plotted between $2.34\times10^{-4}cm/sec\;and\;2.58\times10^{-2}cm/sec$, indicating fine sand and loose silt with a medium grade of permeability. The sedimentary rocks area shows relatively higher permeability coefficients than those volcanic rocks area.

• Journal of the Korean Geotechnical Society
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• v.30 no.2
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• pp.33-42
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• 2014

The shear strength and deformation characteristics of granular soils at low confining stresses differ from those with high confining stresses. Thus, the clear understanding of geotechnical problems related to the low confining stress state such as the stability of shallow foundations, embankments, slope failure, debris flow characteristics and liquefaction as well as the various laboratory model tests is needed. In this study, drained triaxial compression tests with the cell pressures from 5 kPa to 300 kPa were performed on dry Jumunjin sand. The results show that the internal friction angle and deformation modulus are dependent on the confining stress. Also, the correlations between them on the dense and loose sand were established.

• Geomechanics and Engineering
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• v.23 no.1
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• pp.85-92
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• 2020

This study adopted soil test and laboratory physical model experiments to simulate the tailings impoundment accumulation process according to the principle of similarity. Relying on the practical engineering, it analyzed the tailings deposition characteristics on dry beach surface during the damming process, as well as the variation rules of dam saturation line. Results suggested that, the tailings particles gradually became finer along the dry beach surface to inside the impoundment. The particle size suddenly changed at the junction between the deposited beach and the water surface, which displayed an obvious coarsening phenomenon. Besides, the deposited beach exhibited the vertical feature of coarse upward and fine downward on the whole. Additionally, in the physical model, the saturation line elevated with the increase in dam height, and its amplitude was relatively obvious within the range of 1.0-4.5 m away from the initial dam. Under flood condition, the saturation line height was higher than that under normal condition on the whole, with the maximum height difference of 4 cm. This study could provide an important theoretical basis for further studies on dam failure experiments and the evolution rules of leaked tailings flow.