• Journal of the Korean Geotechnical Society
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• v.23 no.4
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• pp.125-132
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• 2007

The oedometer, radial CRS and Rowe cell tests, composite discharge capacity tests and smear effect tests are carried out to estimate the parameters for the reliability-based design of vertical drain method. Also the sensitivity analysis, the probabilistic and deterministic solutions of radial consolidation theory are presented. The result of probabilistic analysis was compared to that of deterministic analysis using the tested and estimated parameters. The results indicated that the drain spacing in the deterministic method is larger than that in the probabilistic method because the former does not consider the uncertainties in the geotechnical property. The divergence of two methods is dependent on the probability of achieving target degree of consolidation by a given time and the coefficient of variation (COV) of the coefficient of horizontal consolidation ($c_h$).

• Tunnel and Underground Space
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• v.31 no.5
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• pp.360-373
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• 2021

Many sources of uncertainty exist in geotechnical analysis ranging from the material parameters to the sampling and testing techniques. The conventional deterministic stability analysis of a plane failure in rock slope produce a safety factor but not a probability of failure or reliability index. In the conventional slope stability analysis by evaluating the ground uncertainty as an overall safety factor, it is difficult to evaluate the stability of the realistic rock slope in detail. This paper reviews some established probabilistic analysis techniques, such as the MCS, FOSM, PEM, Taylor Series as applied to plane failure of rock slopes in detail. While the Monte - Carlo methods leads to the most accurate calculation of the probability of safety, this method is too time consuming. Therefore, the simplified probability methods could be alternatives to the MCS. In this study, using these simple probability methods, the failure probability estimation of a plane failure in rock slope is presented.

• Tunnel and Underground Space
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• v.12 no.3
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• pp.189-197
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• 2002

In recent years, the probabilistic analysis has been used in rock slope engineering. This is because uncertainty is pervasive in rock slope engineering and most geometric and geotechnical parameters of discontinuity and rock masses are involved with uncertainty. Whilst the traditional deterministic analysis method fails to properly deal with uncertainty, the probabilistic analysis has advantages quantifying the uncertainty in parameters. As a probabilistic analysis method, the Monte Carlo simulation has been used commonly. However, the Monte Carlo simulation requires many repeated calculations and therefore, needs much effort and time to calculate the probability of failure. In contrast, the point estimate method involves a simple calculation with moments for random variables. In this study the probability of failure in rock slope is evaluated by the point estimate method and the results are compared to the probability of failure obtained by Monte Carlo simulation method.

• Environmental Analysis Health and Toxicology
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• v.13 no.3_4
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• pp.95-104
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• 1998

INTRODUCTION : Arsenic is a ubiquitous element present in various compounds throughout the earth's crust. The use of arsenic compounds increased greatly during the 18th and 19th centuries, including its use in pigments and dyes, as a preservative of animal hides, in glass manufacture, agricultural pesticides, and various pharmaceutical substances. The causal association between human arsenic exposure, usually in the form of inorganic compounds containing trivalent arsenite (As$^{III}$) or pentavalent arsenate (As$^V$), and various forms of human cancer has been known for many years.

• Journal of the Korean Geotechnical Society
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• v.22 no.11
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• pp.101-111
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• 2006

Slope stability analysis is a geotechnical engineering problem characterized by many sources of uncertainty. Some of them are connected to the variability of soil properties involved in the analysis. In this paper, a numerical procedure of probabilistic analysis of slope stability is presented based on Spencer's method of slices. The deterministic analysis is extended to a probabilistic approach that accounts fur the uncertainties and spatial variation of the soil parameters. The procedure is based on the first-order reliability method to compute the Hasofer-Lind reliability index and Monte-Carlo Simulation. A probabilistic stability assessment was performed to obtain the variation of failure probability with the variation of soil parameters in homogeneous and layered slopes as an example. The examples give insight into the application of uncertainty treatment to the slope stability and show the impact of the spatial variability of soil properties on the outcome of a probabilistic assessment.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.561-568
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• 2002

한국원자력연구소에서 개발중인 액체금속로인 KALIMER는 경수로나 증수로와 근본적으로 설계가 상이하므로 PSA 방법에 대한 새로운 접근방법을 개발해야 한다. 액체금속로 KALIMER에 대한 확률론적 안전성 평가 방법 (PSA, Probabilistic Safety Assessment) 관련 연구는 초기 사건의 도출 및 빈도계산 방법과 주요 계통의 신뢰성 예비 평가에 대한 것이다. 초기 사건이란 원전에 과도 현상을 유발하여 발전소 정지를 초래하는 모든 비정상 사건을 의미하는 것으로 PSA에서 사건 수목을 구성하는 데 기본이 되는 정보이다. 액체금속로는 기존의 경수로 및 중수로와는 전혀 다른 설계를 갖고 있으므로 액체금속로 특유의 초기 사건을 도출하는 방법 및 이들 초기 사건의 빈도를 계산하는 방법에 대한 연구를 수행하였다. KALIMER 주요 계통의 신뢰성 예비 평가를 수행하기 위하여 확률론적 안전성 평가에서 계통분석기법으로 널리 이용되는 고장수목분석의 절차와 방법에 대한 방법론을 선정하여 PSA 방법론을 개발하였다.

• The Journal of Engineering Geology
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• v.20 no.4
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• pp.437-447
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• 2010

A probabilistic analysis of slope stability is an appropriate solution in dealing with uncertainty in problems related to engineering geology. In this study, a Monte Carlo simulation was performed to evaluate the performance function that is Barton's equation. A large number of randomly generated values were obtained for random variables, and the performance function was calculated repeatedly using randomly generated values. A previous study provided information of slope geometry and the random characteristics of random variables such as JRC and JCS. The present approach was adopted to analyze two failed slopes. The probabilities of failure were evaluated for each slope, and sensitivity analysis was performed to assess the influence of each random variable on the probability of failure. The analysis results were then compared with the results of a deterministic analysis, indicating that the probabilistic analysis yielded reliable results.

• Economic and Environmental Geology
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• v.52 no.3
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• pp.231-241
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• 2019

Kinematic analysis determines the stability of rock slope by analyzing the relationship between the slope face orientation and the discontinuity orientation. In this study, terrestrial LiDAR was used to obtain a large amount of discontinuity orientation data and then, the probabilistic characteristics of the orientation data obtained using terrestrial LiDAR were analyzed. Subsequently, the probabilistic kinematic analysis was carried out using the discontinuity orientations generated randomly from Fisher function in Monte Carlo simulation. In addition, the probabilistic kinematic analysis was also performed using the actual orientation data obtained from the terrestrial LiDAR to compare their results. Consequently, the results of both probabilistic analyses showed similar results. Therefore, if sufficient orientation data are provided by other means such as terrestrial LiDAR, the probabilistic analysis will show reasonable results using the actual field data without randomly generating orientation data. In addition, the deterministic kinematic analysis was also carried out using representative orientation of discontinuity sets. The analysis result of the probabilistic analysis showed similar results with the deterministic analysis because the dispersion of the discontinuity orientations in a joint set is not large.

• Nuclear Engineering and Technology
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• v.26 no.4
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• pp.611-626
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• 1994

격납건물 사건수목 방법은 확률론적 안전성 평가시 격납건물 해석의 핵심을 이루는 부분으로서 계통안전 분석으로부터 파악된 주요 노심용융 사고경위와 격납건물 방호계통의 적절한 조합에 의하여 선정된 발전소손상군을 초기조건으로 하여 격납건물 파손 및 방사선원 방출에 영향을 주는 격납건물 내부에서 발생 가능한 주요 사고진행 과정을 체계적으로 다룰 수 있는 유용한 수단이다. 원자력 안전성 향상연구이후 격납건물의 건전성을 확보하기 위한 많은 노력의 결과 현재까지 격납건물 해석 및 논리체계는 상당한 기술적 진보를 이루어 왔으나 아직도 이를 기술하는 방식에는 논쟁의 여지가 많고, 중대사고와 관련된 여러 현상들을 반영할때 그것의 논리적 타당성을 객관적으로 평가할 수 있는 방법이 아직 확고히 정착되지 못함으로 인하여 격납건물 해석결과에는 많은 불확실성 이 존재한다. 또한 아직까지 기존 방법론에 대한 어떠한 종류의 체계적 분석도 이루어지지 않음으로 인하여 이들에 대한 논리적 한계점을 파악하는 데 많은 어려움이 있다. 본 연구에서는 지금까지 주로 개발, 사용되어 온 다양한 격납건물 사건수목 분석 방법론을 소개하고 이들 각각이 지니고 있는 기술적인 문제점을 고찰하며 이를 바탕으로 격납건물 사건수목이 갖추어야 할 기본논리, 구조에 대한 안내지침을 제시함으로써 효과적인 격납건물 해석 및 방법론 개발에 도움을 주고자 한다

• Computational Structural Engineering
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• v.4 no.4
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• pp.125-133
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• 1991

For the purpose of efficiently calculating the design sensitivity and the reliability for the complicated structures in which the structural responses or limit state functions are given by implicit form, the probabilistic finite element method is introduced to formulate the deterministic design sensitivity analysis method and incorporated with the second moment reliability methods such as MVFOSM, AFOSM and SORM. Also, the probabilistic design sensitivity analysis method needed in the reliability-based design is proposed. As numerical examples, two thin plates are analyzed for the cases of plane stress and plate bending. The initial yielding is defined as failure criterion, and applied loads, yield stress, plate thickness, Young's modulus and Poisson's ratio are treated as random variables. It is found that the response variances and the failure probabilities calculated by the proposed PFEM-based reliability method show good agreement with those by Monte Carlo simulation. The probabilistic design sensitivity evaluates explicitly the contribution of each random variable to probability of failure. Further, the design change can be evaluated without any difficulty, and their effect on reliability can be estimated quickly with high accuracy.