Uncertainty and Reliability Analysis Applied to Slope Stability: A Case Study From Sungun Copper Mine (original) (raw)
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Uncertainty and reliability analysis applied to slope stability
Structural Safety, 2000
Nowadays, there are many new methods for slope stability analysis; including probabilistic methods assessing geotechnical uncertainties to develop safety factors. In this paper, a reliability index analysis for the Sungun copper mine slope stability is evaluated based on three methods of uncertainties consisting Taylor series method, Rosenblueth point estimate method and Monte-Carlo simulation method. Sungun copper mine will be one of the Iran's biggest mines with final pit's height of 700 meters. For this study two of its main slopes were assessed, one dipping to the NE (030) and the other to the SE (140). Probability density function of cohesion and angle of friction for the slopes were developed using limit equilibrium methods. These shear strengths were then used to determine the probability density function of safety factor and reliability index using the probabilistic methods. Results of the probabilistic analysis indicate that with ascending values of the uncertainties the reliability index decreases. Furthermore, it was determined that with the Monte Carlo simulation the seed number used has little effect on the reliability index of the safety factor especially with seed numbers in excess of 1200. Variations in the overall reliability index of safety factor were observed between the two slopes and this difference is explained by the differences in complexities of the geology within the cross-section.
Reliability Analysis of Slope Stability at Nuclear Power Plant Site
2009
It is well known that great uncertainty and variability exist in subsurface materials regarding layer uniformity and soil/rock engineering properties, as well as seismic loadings to be considered. Those uncertainties and variability not only affect the stability of the subsurface materials and foundations, but also affect the stability of the slopes that are usually present at the site, especially when seismic loadings are involved. This study focuses on the impact of the uncertainties of soil and seismic loads on the slope stability analysis and how to determine the reliability of the analysis results in terms of factor of safety. In this study, uncertainties involved in the slope stability analysis were first identified, then a practical engineering procedure is proposed to apply probability analysis method that takes those uncertainties into consideration and uses reliability index as the reliability measurement of the factor of safety of slope stability. After conducting sensiti...
Evaluation of reliability assessment in slope stability analysis
8th National Congress on Civil Engineering, 2014
The method of Bishop is one of the most practical approaches in limit equilibrium analysis for slope stability analysis. Three variables such as unit weight, friction angle and cohesion are the soil parameters of this method that must be selected as stochastic variable because of uncertainties of soil. In this research, these parameters are selected stochastic and the effect of them is considered in determining the safety factor in this method. Numerical and analytical approaches are used for this purpose and the results are compared to each other. Compassion indicates good performance and close results of the approaches for reliability assessment of slope stability.
Proceedings of the First Asia Pacific Slope Stability in Mining Conference, 2016
Slope stability analysis is a branch of ground engineering science where there are a number of significant uncertainties. Although probabilistic slope stability analysis is an option in most commercial software, the use of this method is not common in practice. Apart from the ability of the probabilistic method to assess the impact of uncertainties on slope stability, it can also be used as a tool to optimise the geotechnical site investigation program. The first-order second-moment approximation of the Taylor series method is one of the probabilistic slope stability methods that determines the relative contribution of uncertainty projected by each component random variable. For a slope with a sequence of different geological units, each unit can be modelled as having several random variables such as cohesion and friction angle. A geological unit whose random variables are responsible for the greatest contribution to the uncertainty in the Factor of Safety (FS) will be the most controlling unit. This characteristic can be used to design geotechnical site investigation programs in order to minimise the uncertainties in these controlling units, which will enhance the Reliability Index of the computed FS.
Factor of Safety and Reliability Analysis of Rock Slope using GEO5 Software
The entire earth consist of so many varieties of rock minerals which compositely for an entire rock mass which may be natural or artificial rock slopes which are at the level of the ground itself or it may be a deepest cuts or the hill slopes above the ground level. The factor of safety plays a major role in rock slope analysis. Due to the uncertainty involved in the calculation of rock parameters the application of factor of safety is widely used in analysis. Theses factor of safety are determined here by using Geo5 demo version software based on the uncertainty involved in the various rock parameters. The simple reliability analysis will provides the means of combined effect of uncertainty involved in calculations. The additional parameters such as standard deviation, mean, reliability index are used to determine the probability of failure of the rock slope. This probability of failure will helps to determine the reliability of the rock slope which in turn gives the idea of the stability of rock slope for any future recommendations regarding the actions for their stability.
Probability Methods for Stability Design of Open Pit Rock Slopes: An Overview
Geosciences, 2021
The rock slope stability analysis can be performed using deterministic and probabilistic approaches. The deterministic analysis based on the safety concept factor uses fixed representative values for each input parameter involved without considering the variability and uncertainty of the rock mass properties. Probabilistic analysis with the calculation of probability of failure instead of the factor of safety against failure is emerging in practice. Such analyses offer a more rational approach to quantify risk by incorporating uncertainty in the input variables and evaluating the probability of the failure of a system. In rock slope engineering, uncertainty and variability involve a large scatter of geo-structural data and varied geomechanical test results. There has been extensive reliability analysis of rock slope stability in the literature, and different methods of reliability are being employed for assessment of the probability of failure and the reliability of a slope. Probabi...
Reliability Analysis On The Stability Of Slope
2005
2.3 Probability of Failure Criteria for slope 2.4 Target Reliability Indices (US Army, 1999) 4.1 Soil properties used for hypothetical case 4.2 Result of probabilistic analysis for case 1 to 3 and c-φ uncorrelated 4.3 Result of probabilistic analysis for case 1 to 3-with c-φ correlation coefficient of-0.5. 4.4 Sensitivity result for cases of c-φ uncorrelated 4.5 Sensitivity result for cases with c-φ correlation coefficient of-0.5 4.6 Soil data of peak strength and residual strength parameter obtained from direct shear test 4.7 Result using data from direct shear box test.
Comparative Analysis of Reliabity Methods Applied to Rock Slope Stability
Over the last years, it has become increasingly popular to include both deterministic (i.e., Factor of Safety) and probabilistic (i.e., Probability of Failure) methods in defining acceptability criteria for the design of operating mines and mining projects in Chile. There are many different methods available to calculate Probability of Failure, and each has its advantages and disadvantages. There are methods that are considered more rigorous nevertheless time-consuming to perform, while the less rigorous ones are generally simpler and faster to implement. This paper points out the most frequently used methods for calculating Probability of Failure of rock slopes in Chilean Practice. Among them, there are those that are approximations from Taylor Series, specifically the First Order Second Moment (FOSM), Monte Carlo and Latin Hypercube, Monte Carlo with Response Surface, and Point Estimate Method. In this paper Limit Equilibrium Modeling was chosen to develop a comparative analysis among the reliability methods in a hypothetical slope comprised of Mohr-Coulomb materials and a simplified rock slope from a Chilean mining operation.
Geosciences, 2020
The rock slope stability assessment can be performed by means of deterministic and probabilistic approaches. As the deterministic analysis needs only representative values (generally, the mean value) for each physical and geo-mechanical parameter involved, it does not take into account the variability and uncertainty of geo-structural and geo-mechanical properties of joints. This analysis can be usually carried out using different methods, such as the Limit Equilibrium method or numerical modeling techniques sometimes implemented in graphical tests to identify different failure mechanisms (kinematic approach). Probabilistic methods (kinetic approach) aimed to calculate the slope failure probability, consider all orientations, physical characters and shear strength of joints and not only those recognized as kinematically possible. Consequently, the failure probability can be overestimated. It is, therefore, considered more realistic to perform both kinematic and kinetic analyses and ...