• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1102-1106
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• 2006

본 연구에서는 현재 제방 사면에 적용된 자연친화적인 호안공 중 블록공을 대상으로 수리적인 안정성 및 식생 활착성 등을 검토하는 것을 주요 목적으로 하였다. 일반적으로 블록 호안공은 수리적인 안정성을 갖지만, 호안공 배면에 토사유출 방지를 목적으로 부직포를 설치하는데, 이 경우 호안공 두께가 그리 크지 않아 홍수시 또는 인위적인 행위에 의해 호안공이 쉽게 어긋날 우려가 있다. 또한 부직포 위에 호안공을 설치하는 까닭에 마찰이 적어 홍수시 흐름의 소류력에 의해 쉽게 미끄러질 우려가 있으며, 경사면과 부직포 사이로 물이 들어갈 경우 부직포가 배수가 되지 않기 때문에 부직포 배면의 토사는 부분 흘러내림 현상으로 토사 유출에 따른 부등침하와 블록의 내려앉음 현상이 발생되는 우려가 발생된다. 현지조사 결과 블록공 배면에 설치되는 부직포는 식물 뿌리가 뚫고 들어가지 못하므로 식생활착이 불충분함이 나타났다. 따라서 상기 결과를 종합하여 볼 때, 수리적인 안정성과 식생 활착을 동시 만족시키는 호안공은 부직포가 설치된 호안공으로서 부직포는 식물 뿌리가 뚫고 들어갈 수 있는 형태이어야 하며, 호안공 공극에 충분한 식생이 활착할 수 있는 면적을 갖는 형태이어야 한다.

• The Journal of Engineering Geology
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• v.23 no.1
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• pp.57-65
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• 2013

We developed a computer program (CDFlow v. 1.0) to design countermeasures against debris flows in natural terrain. The program can predict the probability of landslides occurring in natural terrain and can estimate the zone of damage caused by a debris flow. It can also be used to design the location and size of countermeasures against the debris flow. The program is run using the ArcGIS Engine, which is one of the most well-known Geographic Information System (GIS) tools for developers. The quasi-dynamic wetness index and the infinite slope stability equation were applied to predict landslide probability as a type of slope safety factor. The calculated safety factor was compared with the required safety factor, and areas of high probable potential for landslides were then selected and represented on the digital map. The volume of debris flow was estimated using these areas of high probable potential for landslides and soil depth. The accumulated volume of debris flow can be calculated along the flow channel. To assess the accuracy of the program, it was applied to a real landslide site at Deoksan-ri, Inje-gun, Kangwon-Province, where four debris barriers have been installed in the watershed of the site. The results of soil tests and a field survey indicate that the program has great potential for estimating probable landslide areas and the trajectory of debris flows. Calculation of the capacity volume of existing debris barriers revealed that they had insufficient capacity to store the calculated amount of debris flow. Therefore, this program enables a rational estimation of the optimal location and size of debris barriers.

• The Journal of Engineering Geology
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• v.30 no.4
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• pp.447-456
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• 2020

The study area is a slope in Dogye-eup, Samcheok-si, Gangwon-do. The cutting method was applied to this slope for stabilization in 2009 due to the influence of the waste-rock dump located at the top of slope. Recently, soil cracks and creep have occurred on this slope, and the drainage channel was damaged. Therefore, it was analyzed the topography change through photogrammetry using a UAV. Orthophotos were taken in April and October 2019 respectively. From the Orthophots, Digital Surface Model (DSM) was extracted. Time series analysis was performed by comparing each DSM. The topography of October was pushed forward while maintaining the topography of April. Through these features, it is judged that the soil creep is occurring in this study area.

• Journal of the Korean Geotechnical Society
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• v.17 no.4
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• pp.221-229
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• 2001

연약지반의 측방유동으로 인한 피해가 예상되는 국내 현장에 성토지지말뚝공법을 적용하기 위한 연구의 일환으로 실제 현장에서 성토지지말뚝이 발휘하는 효과를 규명하기 위한 현장시험이 계획되었다. 본 현장시험은 직경 40.64cm의 강관말뚝을 3본씩 총 4여로 시공하고, 각 열의 줄말뚝은 콘크리트캡보로 연결한 다음 총 8m까지 성토하였다. 현장시험은 총 2회에 걸쳐 수행하였으며, 성토지지말뚝의 하중분담효과를 확인하기 위해 하중계, 토압계, 지중경사계, 그리고 침하판을 이용한 계측을 실시하였다. 또한 계측결과를 제안이론식과 비교분석하였다. 이러한 연구 결과 성토지지말뚝을 시공할 경우 성토지지말뚝 위 성토지반속에 발달하는 지반아치에 의해 대부분의 성토하중이 말뚝으로 전이됨을 확인하였고, 말뚝캡보의 설치 간격이 좁을수록, 그리고 성토고가 높을수록 성토지지말뚝의 하중분담효과가 더 커지게 됨을 확인할 수 있었다. 또한 설계시 성토지지말뚝의 설치범위를 합리적으로 결정하기 위해서는 성토지지말뚝이 성토사면의 사면안정효과에 미치는 영향을 고려해야 함을 알 수 있었으며, 제안이론식이 현장상태의 성토지지말뚝에 합리적으로 적용될 수 있음을 입증하였다.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.2
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• pp.117-126
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• 2021

An experimental study was carried out to investigate the applicability of cement-based materials for green soil which is a soil for promoting plant growth. The results show that the shear strength of the green soil mixed with gypsum cement (No.3) was low, but the hardness (23.6mm) and pH value (7.4) was most suitable for the vegetation environment. In addition, the initial vegetation germination of green soil, which improved performance by adding a moisturizer, was slower than that of general green soil, and the conductivity value tended to be slightly higher. On the other hand, the slope adhesion of advanced green soil was high, and it was found that the plant growth rate and the regeneration capacity were superior after time passed.

• Journal of the Korean Geosynthetics Society
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• v.23 no.2
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• pp.1-7
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• 2024

Various innovative technologies and methods are being applied to ensure the stability of steep rock slopes. However, there are design limitations concerning site ground conditions, leading to discrepancies between the designed and actual ground conditions during construction. In the case of the retaining wall in Yeosu, where the study area is located, although the construction of a 5-stage retaining wall is planned, at the current completion of the second stage, cracks on the upper part of the wall, settlement in the front of the wall, and seepage have been observed. After the completion of stages one and two, issues regarding cracks and settlement on the upper part of the wall and seepage in the front of the wall were discovered. Thus, there was a need to reevaluate the results of the existing stability assessment. It was confirmed that the issue was due to groundwater leakage, attributed to the lack of clear assessment of the colluvial soil layer during the initial design stage. Therefore, to conservatively reflect groundwater level conditions, a groundwater level contour was positioned at the top of the wall to conduct a slope stability assessment. The assessment results indicated that the safety factor during the rainy season exceeded the required value of 1.3, with a calculated safety factor of 1.31. However, during seismic events, the safety factor was determined to be 1.12, falling short of the required safety factor of 1.3. Therefore, it is suggested that the existing retaining walls constructed during stages one and two undergo reinforcement using methods such as micro-piles with grouting, and additional work should be carried out to ensure a clear assessment of the colluvial soil layer.

• Journal of Conservation Science
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• v.20
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• pp.89-103
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• 2007

The bedrock beneath the Chokseongnu pavilion consists of sandstone with alternate dark-gray to light-brown siltstone and dark-gray shale of the Jinju Formation, where bedding is well developed toward the Chokseongmun gate. Large to small joints and overbreak from the erosion weathering have been developed in the bedrock. Besides, water leakage from development of discontinuity planes, fragmentation of shale, crack and joint by tree roots are observed on the bedrock. While shale and siltstone showed high sensitivity in physical and chemical weathering, respectively, sandstone indicated the highest weathering sensitivity in both. As the results of structural stability analysis, the whole bedrock has high instability in wedge failures, and especially section No. II slope is more instable than section No. I. Therefore, it is necessary for the bedrock to be strengthened by improvement method for soft foundations and the surface reinforcement. The trees causing mechanical collapse of the bedrock should be also removed and a water flow prevention measure or a water exhaust are required.

• Journal of the Korean Geotechnical Society
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• v.28 no.7
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• pp.5-16
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• 2012

Soil-nailing is the most popular method of reinforcing for slope stability. In general, two factors are considered as failure modes during the soil-nailing design stages: pullout failure mode and shear failure mode that will occur on the most probable failure plane. In many cases, however, shallow failure can also occur when the ground near the slope face is swept away by the horizontal stress release during the staged top-down excavation. In this paper, an optimized soil-nailing design methodology is proposed by considering the three failure modes mentioned above: pullout failure; shear failure; and shallow failure. The variables to be optimized include the bonded length and number of soil-nailings, and the confining pressure that should be applied at the slope face. The procedure to obtain the optimized design variables is as follows: at first, optimization of soil-nailings, i.e. bonded length and number, against pullout and shear failure modes; and then, optimization of confining pressure at each excavation stage that is needed to prevent shallow failure. Since the two processes are linked with each other, they are repeated until the optimized design variables can be obtained satisfying all the constrained design requirements in both of the two processes.

• Journal of the Korean Geotechnical Society
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• v.25 no.7
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• pp.35-46
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• 2009

Pressure grouting is a common technique in geotechnical engineering to increase the stiffness and strength of the ground mass and to fill boreholes or void space in a tunnel lining and so on. Recently, the pressure grouting has been applied to a soil-nailing system which is widely used to improve slope stability. The soil-nailing design has been empirically performed in most geotechnical applications because the interaction between pressurized grouting paste and the adjacent ground mass is complicated and difficult to analyze. The purpose of this study is to analyze the increase of pullout resistance induced by pressurized grouting with the aid of performing laboratory model tests and field tests. In this paper, two main causes of pullout resistance increases induced by pressurized grouting were verified: the increase of mean normal stress and the increase of coefficient of pullout friction. From laboratory tests, it was found that dilatancy angle could be estimated by modified cavity expansion theory using the measured wall displacements. The radial displacement increases with dilatancy angle decrease and the dilatancy angle increases with injection pressure increase. The measured pullout resistance obtained from field tests is in good agreement with the estimated one from the modified cavity expansion theory.

• Geotechnical Engineering
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• v.14 no.3
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• pp.73-94
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• 1998

In the present study, a method of the three-dimensional limit equilibrium stability analysis of shape of the potential failure wedge for the concave-shaped excavation corner is assumed on the basis of the results of the FLACSU program analysis. Estimation of the three-dimensional seepage forces expected to act on the failure wedge is made by solving the three-dimensional continuity equation of flow with appropriate boundary conditions. By using the proposed method of three-dimensional stability analysis of the concave-shaped excavation corner, a parametric study is performed to examine the reinforcement effect of skew soil nailing system, range of the efficient skew angles and seepage effect on the overall stability. Also examined is the effect of an existence of the right-angled excavation corner on three-dimensional deflection behaviors of the convex-shaped skew soil nailing walls. The results of analyses of the convexshaped excavation corner with skew soil nailing system is further included to illustrate the effects of various design parameters for typical patterns of skew nails reinforcement system.