• KSCE Journal of Civil and Environmental Engineering Research
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• v.4 no.3
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• pp.11-18
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• 1984

There are two different methods in the stability analysis of slopes depending upon the 1ocations and the types of assumed failure planes, which are the infinite slope analysis and the finite slope analysis. The infinite slope analysis is simple and easier in its application. However, since the method neglects the end effects and assumes the failure plane to be located at the shallow depth and parallel to the slope, the slopes to be analyzed by the method should be limited to a certain range. Thus, it is intended in this paper to define the infinite slopes whose stability may be analyzed by the infinite slope analysis. As a result, it is obtained that the method of infinite slope analysis may be applied to the slopes which have the ratio of the slope height to the depth of the failure plane of 9 or bigger.

• The Journal of Engineering Geology
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• v.21 no.3
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• pp.247-257
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• 2011

In this study the infinite slope model, one of the physical landslide models has been suggested to evaluate the susceptibility of the landslide. However, applying the infinite slope model in regional study area can be difficult or impossible because of the difficulties in obtaining and processing of large spatial data sets. With limited site investigation data, uncertainties were inevitably involved with. Therefore, the probabilistic analysis method such as Monte Carlo simulation and the GIS based infinite slope stability model have been used to evaluate the probability of failure. The proposed approach has been applied to practical example. The study area in Boeun area been selected since the area has been experienced tremendous amount of landslide occurrence. The geometric characteristics of the slope and the mechanical properties of soils like to friction angle and cohesion were obtained. In addition, coefficient of variation (COV) values in the uncertain parameters were varied from 10% to 30% in order to evaluate the effect of the uncertainty. The analysis results showed that the probabilistic analysis method can reduce the effect of uncertainty involved in input parameters.

• Journal of the Korean GEO-environmental Society
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• v.8 no.2
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• pp.11-18
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• 2007

Slope failure triggered by rainfall produces severe effects on the serviceability and stability of railway, Therefore, slope stability problem is one of the major concerns on the operation of railway. In this study, the rainfall conditions triggering slopes failure adjacent to railroads are investigated and the numerical analysis approach in consideration of infiltration and limit equilibrium method based upon multiple slip surfaces are proposed. The rainfall conditions triggering slope failure are as follow: cumulative rainfall is in the range of 150~500 mm, and duration is from 3 to 24 hours. Base upon the rainfall conditions, infiltration analysis and limit equilibrium method for infinite slope condition are carried out. The depth of infinite slope is assumed as 2 m and the multiple slip surfaces modeled with 16.7 cm interval from the bottom slip surface located at the 2 m depth. The assumed bottom slip surface is the location at which factor of safety is converging. The proposed approach shows more reasonable results than the results from the general codes assuming water table at slope surface. In addition, three dimensional plot of cumulative rainfall, rainfall duration, and factor of safety shows that slope stability analysis in consideration of rainfalll must account for cumulative rainfall (rainfall duration).

• Journal of the Korean Association of Geographic Information Studies
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• v.16 no.3
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• pp.193-210
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• 2013

This study aims to assess the slope stability variation of Jeollabuk-do drainage areas by RCM model outputs based on A1B climate change scenario and infinite slope stability model based on the specific catchment area concept. For this objective, we downscaled RCM data in time and space: from watershed scale to rain gauge scale in space and from monthly data to daily data in time and also developed the GIS-based infinite slope stability model based on the concept of specific catchment area to calculate spatially-distributed wetness index. For model parameterization, topographic, geologic, forestry digital map were used and model parameters were set up in format of grid cells($90m{\times}90m$). Finally, we applied the future daily rainfall data to the infinite slope stability model and then assess slope stability variation under the climate change scenario. This research consists of two papers: the first paper focuses on the methodologies of climate change scenario preparation and infinite slope stability model development.

• Journal of Korea Water Resources Association
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• v.45 no.7
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• pp.643-656
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• 2012

There has been an increase for the landslide areas and restoration expenses due, in large part, to the increased locally heavy rains caused by recent climate change as well as the reckless development. This study carried out a slope stability analysis by the application of distributed wetness index, using the GIS-based infinite slope stability model, which took the root cohesion effect into consideration, for part of Mt. Umyeon in Seoul, where landslide occurred in July 2011, in order to compensate the defects of existing analysis method, and subsequently compared its result with the case on the exploitation of lumped wetness index. In addition, this study estimated the distributed wetness index by methodology, applying three methods of specific catchment area calculation: single flow direction (SFD), multiple flow direction (MFD), and infinity flow direction (IFD), for catchment area, one of the variables of distributed wetness indices, and finally implemented a series of comparative analysis for slope stability by methodology. The simulation results showed that most unstable areas within the study site were dominantly located in cutting-area surroundings along with the residential area and the mountaintop and unstable areas of IFD and lumped wetness index method were similar while SFD and MFD provided smaller unstable areas than the two former methods.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.512-515
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• 2012

최근의 재해 발생은 하천에 의한 범람, 제방의 붕괴 등에 의한 피해발생보다는 일정지역에 국한적으로 내수배제 불량, 토사유출, 산사태 등으로 인한 피해의 발생이 증가하고 있다. 특히나 도시지역과 신규개발지역을 중심으로 집중호우로 인한 토사유출 등으로 인한 배수로 막힘, 산사태등의 2차적인 피해가 증가하고 있는 추세이다. 2011년의 서울의 우면산 산사태 등과 같은 도시중심에서의 피해와 강원도 등의 신규개발지역에서의 토사로 인해 2차, 3차 피해는 국지적이고 예측이 불가능한 곳에서 발생되고 있다. 이러한 토사유출, 산사태에 의한 예측기법은 최근의 정보기술의 발달로 인해 보다 다양한 방법의 접근들이 시도되고 있으며, 이에 대한 정량적인 평가기법들이 개발되고 적용되고 있다. 본 연구에서는 산지지형의 소규모 개발지의 토사재해의 위험성을 평가하기 위하여 GIS 기술을 이용한 사면의 안정성과 산사태 위험성을 평가하는 대표적인 방법으로 Pack et al. (1998)이 제안한 수리적 무한사면 안정모델과 결합하여 사면안정분석을 위해 개발된 SINMAP을 이용하여 소규모 개발지역의 토석류 해석과 사면의 안정성 검토 그리고 범용토양공식을 이용하여 토사유출량을 산정하여 개발지역내 사면 및 토사재해의 위험성을 평가하였다. GIS를 이용한 지형적 특성에 따른 사면의 위험성과 토사유출량 해석 결과를 이용하여 소규모 개발지역의 토사재해의 위험성을 정량적이고 다각적으로 평가하여 재해발생에 따른 위험성을 노출하고 이에 대한 대책 수립에 도움이 될 것으로 판단된다.

• The Journal of Engineering Geology
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• v.28 no.1
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• pp.11-24
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• 2018

The purpose of slope stability analysis is to predict the location and occurrence time considering the rainfall, topographic and soil characteristics, etc. In this study, infinite slope stability analysis considering the time distribution characteristics of the daily maximum rainfall was conducted using a model that combines a digital terrain model and a groundwater flow model. As the results of slope stability analysis, 69.1~70.0% of Fs < 1 cells are in the range of slope angle $20{\sim}50^{\circ}$ and Fs < 1 starts to appear in 2 hours for $Q_1$ model, 5 hours for $Q_2$, 7 hours for $Q_3$ and 6 hours for $Q_4$. Furthermore, the maximum number of Fs < 1 cells appear in 6 hours for $Q_1$ model, 12 hours for $Q_2$, 16 hours for $Q_3$ and 20 hours for $Q_4$, and the area of Fs < 1 is 14.3% for $Q_1$ model, 15.0% for $Q_2$, 15.6% for $Q_3$, and 16.3% for $Q_4$.

• Journal of the Korean Association of Geographic Information Studies
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• v.17 no.3
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• pp.1-19
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• 2014

This study aims to assess the slope stability variation of Jeonbuk drainage areas by RCM model outputs based on A1B climate change scenario and infinite slope stability model based on the previous research by Choi et al.(2013). For a large-scale slope stability analysis, we developed a GIS-based database regarding topographic, geologic and forestry parameters and also calculated daily maximum rainfall for the study period(1971~2100). Then, we assess slope stability variation of the 20 sub-catchments of Jeonbuk under the climate change scenario. The results show that the areal-average value of safety factor was estimated at 1.36(moderately stable) in spite of annual rainfall increase in the future. In addition, 7 sub-catchments became worse and 5 sub-catchments became better than the present period(1971~2000) in terms of safety factor in the future.

• Journal of the Korean Geotechnical Society
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• v.34 no.5
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• pp.37-51
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• 2018

The slope failure due to the rainfall infiltration occurs frequently in Korea, since the depth of the weathered residual soil layer is shallow in mountainous region. Depth of the failure surface is shallow and tends to pass near the interface between impermeable bedrock and soil layer. Soil parameters that have a significant impact on the instability of unsaturated slopes due to rainfall infiltration inevitably include large uncertainties. Therefore, this study proposes a probabilistic analysis procedure by Monte Carlo Simulation which considers the hydraulic characteristics and strength characteristics of soil as random variables in order to predict slope failure due to rainfall infiltration. The Green-Ampt infiltration model was modified to reflect the boundary conditions on the slope surface according to the rainfall intensity and the boundary condition of the shallow impermeable bedrock was introduced to predict the stability of unsaturated soil slope with shallow bedrock under constant rainfall intensity. The results of infiltration analysis were used as inputs of infinite slope analysis to calculate the safety factor. The proposed analysis method can be used to calculate the time-dependent failure probability of soil slope due to rainfall infiltration.

• Journal of Korean Society for Geospatial Information Science
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• v.14 no.3 s.37
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• pp.55-62
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• 2006

The purpose of the current research is to evaluate the possibility of landslides by using geo-spatial information system. Geological information has been summarized and stability analysis for infinite slopes has been conducted based on the force equilibrium. In addition, the analysis of landslides was performed based on probabilistic approach by using probabilistic variables which can include uncertainty of input parameters. For the purpose of testifing the applicability of the analysis method actual geological data from a construction site was obtained, thereby performing both a preliminary analysis for a large area and detailed analysis for a better result. As a result of the current analysis several issues such as the possibility of development of landslides, detailed analysis of where landslides are most likely to be developed were analysed by using two concepts of safety and index of failure probability.