• Journal of the Korean Geotechnical Society
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• v.21 no.6
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• pp.137-146
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• 2005

299 railroad slopes were investigated and the failure characteristics and reinforcement patterns were analyzed. Stability analyses on the 14 cut-off soil slopes were carried out. Surficial failures were predicted by infinite slope analyses assuming the temporarily perched ground water table at soil surface during rainfall period. Limit equilibrium analyses were also carried out and 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 adequacy of those analyses was evaluated by comparing the slope failure characteristics between analysis results and the past failure records. From the comparison results, it was deduced that the limit equilibrium analyses were not appropriate to estimate the shallow failure that occurred at most of the railroad cut-off soil slopes. For the better estimation of the surficial failure, not only the increase of pore-water pressure (reduction of matric suction), but also the influence of water flows over slope surface which erode soil mass, should be evaluated and considered.

• Journal of The Korean Society of Agricultural Engineers
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• v.48 no.1
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• pp.71-79
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• 2006

In Korea, most landslides occurred during the rainy season and had a shallow failure plane parallel to the slope. For these types of rainfall-induced failures, the most important factor triggering slope unstability is decrease in the matric suction of unsaturated soils with increasing saturation depth by rainfall infiltration. The saturation depth was readily estimated using modified Green-Ampt model proposed by Chu et al. (Chu Model) at present. But Chu Model involves some problems for application, because water-redistribution phenomena were not effected. So the modified Chu Model (MCGAM) which reflect water redistribution phono mens was developed. The results showed that the MCGAM had a better agreement with measured volumetric water contents than existing Chu Model.

• Journal of the Korean GEO-environmental Society
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• v.20 no.12
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• pp.49-55
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• 2019

Slope failure analysis entails proper understanding of various factors as well as the characteristics of ground conditions, which are difficult to achieve due to technological limits. Despite a number of past studies to clarify possible factors triggering slope failures, the impact of rainfall characteristics and infiltration rate, which are the key to estimation of slope stability in wet condition, on slope failures still remains unclear. This study has estimated permeability against various unit weights of soil based on constant head permeability tests using Jumunjin standard silica sand. One dimensional infiltration tests were conducted to estimate the infiltration capacity and the amount of infiltration taking into account the permeability and rainfall intensity. The applicability of existing empirical equations for the estimation of infiltration to granular soils was verified on the basis of the test results.

• The Journal of Engineering Geology
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• v.11 no.2
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• pp.153-161
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• 2001

The quantitative evaluation of the stereo graphic projection, the limit equilibrium analysis, the finite difference analysis, the distinct element methocI is a analytical evaluation using many variables. Through the reliability analysis by the point estimation technique, uncertainty of other variables that have an effect on the stability of the rock slo~ was considered. The organized evaluation method of the approximate reasoning concept and using a fuzzy language was developed to confer and analysis the failure factors in planning and constructing the rock slope. Considering the result of the an- alysis, it was demonstrated that stability of entire sections can be evaluated through reliability analysis of point estimation technique. The results of stability evaluation by Fuzzy Approximate Reasoning is generally identical with the results of other existirw; analyses. As mentioned above, general and organized evaluation of special qualities of rock slope is possible using RMR Classification, Stereo Graphic Projection, Limit Equilibriwn Analysis, Finite Difference Analysis, Distinct Element Method, Point Estimation Technique, and Fuzzy Approximate Reasoning.

• Journal of the Korean GEO-environmental Society
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• v.9 no.5
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• pp.61-69
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• 2008

In general, it has been usually used the method that assess rock slope stability using stereographic projection method, limit equilibrium analysis, numerical analysis and slope stability evaluation table. Several methods for assessing the stability of rock slopes has been proposed on the basis of site investigation data. These method adopted different evaluation items and weighting factors by researchers, organization and nation. But the researches for each evaluation items were insufficient. So the effectiveness of rock slope stability evaluation items for geometrical configuration (slope height, slope direction and angle, dip and dip direction of major discontinuity, absolute value for the direction difference for slope and major discontinuities) and topographical characteristic (possibility of topographical water concentration, upper natural slope angle, slope configuration) using 315 failure and stable highway rock slope analysis data, AV (abnormal value) analysis and NMAV (normalized maximum abnormal value) analysis were evaluated.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.3 no.3
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• pp.95-106
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• 1983

The probability of failure is used to analyze the reliability of three dimensional slope failure, instead of conventional factor of safety. The strength parameters are assumed to be normal variated and beta variated. These are interval estimated under the specified confidence level and maximum likelihood estimation. The pseudonormal and beta random variables are generated using the uniform probability transformation method according to central limit theorem and rejection method. By means of a Monte-Carlo Simulation, the probability of failure is defined as; $$P_f$$=M/N N: Total number of trials M: Total number of failures some of the conclusions derived from the case study include; 1. If the strength parameters are assumed to be normal variated, the relationship between safety factor and the probability of failure is fairly consistent, regardless of the procedures of analysis and dimensions of assumed rupture surfaces. 2. However if the strength parameters are beta variated, general relationship between $F_s$ and $P_f$ is hardly found.

• Geomechanics and Engineering
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• v.5 no.2
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• pp.143-164
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• 2013

Calculation of seismic displacements in reinforced slopes plays a crucial role in appropriate design of these structures however current analytical methods result indifferent values for permanent displacements of the slope. In this paper, based on limit equilibrium and using the horizontal slices method, a new formulation has been proposed for estimating the seismic displacements of a reinforced slope under earthquake records. In this method, failure wedge is divided into a number of horizontal slices. Assuming linear variations for tensile forces of reinforcements along the height of the slope, the coefficient of yield acceleration has been estimated. The simplicity of calculations and taking into account the frequency content of input triggers are among the advantages of the present formulation. Comparison of the results shows that the yield acceleration calculated by the suggested method is very close to the values resulted from other techniques. On the other hand, while there is a significant difference between permanent displacements, the values obtained from the suggested method place somehow between those calculated by the other techniques.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1271-1278
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• 2010

대규모 절토사면 유지관리 시스템 운영간 적절한 장소에 합리적인 공법을 선정하여 시공하는 것은 중요한 일이다. 다양한 옹벽 시공 공법이 있지만 시공성과 경제성을 감안할 때 옹벽의 기능을 최대한 유지하면서 친환경 기술을 접목할 수 있는 돌망태 옹벽은 최근 사면 보강에 빈번히 시공되고 있다. 장기간 그 기능을 유지해야하는 옹벽의 경우는 유지관리가 더욱더 중요한 과제이다. 따라서 본 연구에서는 돌망태 옹벽의 시공 및 유지관리 점검에 대한 방안을 사례분석을 통하여 제안하고자 한다.

• Journal of the Korean Geotechnical Society
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• v.34 no.4
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• pp.5-11
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• 2018

In conventional analytical solutions for rainfall-induced soil slope stability, the Green-Ampt (1911) equation for estimating the saturation depth and the Skempton & DeLory (1957) equation for calculating the infinite slope shallow failure were compared with the numerical analysis to confirm the error. In the simple evaluation of the reason of soil slope instability due to rainfall using the conventional equations, there are many errors and, overestimation or underestimation of the calculation results. In this study, the equation consisting of the results obtained from infiltration analysis on unsaturated soil slope is proposed by applying the average range of the strength parameters of the granite weathered soils, and its reliability is verified by comparing with the numerical analysis results. The developed equation can be used easily in various fields for the estimation of slope safety factor by checking the rainfall duration and saturation depth.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.4 no.3
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• pp.75-83
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• 1984

The probability of failure is used to analyze the reliability of three dimensional slope failure, instead of conventional factor of safety. The strength parameters are assumed to be normal variated and beta variated. These are interval estimated under the specified confidence level and maximum likelihood estimation. The pseudonormal and beta random variables are generated using the uniform probability transformation method according to central limit theorem and rejection method. By means of a Monte-Carlo Simulation, the probability of failure is defined as; $P_f=M/N$ N: Total number of trials M: Total number of failures Some of the conclusions derived. from the case study include; 1. Three dimensional factors of safety are generally much higher than 2-D factors of safety. However situations appear to exist where the 3-D factor of safety can be lower than the 2-D factor of safety. 2. The $F_3/F_2$ ratio appears to be quite sensitive to c and ${\phi}$ and to the shape of the 3-D shear surface and the slope but not to be to the unit weight of soil. 3. From the two models (normal, beta) considered for the distribution of the factor of safety, the beta distribution generally provides lager than normal distribution. 4. Results obtained using the beta and normal models are presented in a nomgraph relating slope height and slop angle to probability of failure.