Slope Stability Analysis Method Research Articles

Footwall slope stability analysis with the numerical manifold method

This paper extends the numerical manifold method (NMM) for footwall slope stability analysis. A fracturing algorithm based on the Mohr–Coulomb criterion with a tensile cutoff is implemented into the NMM code. The developed program is first calibrated by simulating four typical crack problems. It is then applied to analyze the potential footwall slope instability. Parametric studies with respect to dip of a bedding plane, orientation of a predominant joint set, the bedding profile, etc., are carried out. Numerical results indicate that the developed program can simulate the opening and sliding along pre-existing discontinuities, fracturing through intact rock, as well as kinematics of the failed slope, and can also reproduce the major failure mechanisms observed in footwall slope collapses. The NMM is promising for such problems and deserves to be further developed to be practically used in natural/excavated rock slope stability analysis and open pit slope design.

Uncertainty and Reliability Analysis Applied to Slope Stability: A Case Study From Sungun Copper Mine

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.

Stability Analysis of Slope with Arbitrary Sliding Surface on Multi Strata Using Minimum Potential Energy Principle

As a rule,the natural slope is not homogeneous,and its sliding surface is arbitrary. However,the common slope stability analysis methods used to assume shape of sliding surface and slope homogeneity,and the calculation process is so complex that accuracy of results is decreasing.In this study,the potential energy function of sliding body is established for slope with arbitrary sliding surface on multi strata.Using minimum potential energy principle, the displacement of sliding body can be got. Then based on Moore - Coulomb criterion and condition of force equilibrium in the sliding direction, the safety factor can be got directly. Case studies show: ①This slope stability analysis methods is valid.② Different definition of safety factor leads to different analysis result.

Analysis of Earth-Rockfill Dam Slope Stability by Strength Reduction Method Based on Nonlinear Strength

In the design process of the earth-rock dam, the slope stability problem was always focused on. The shear strength of rockfill in the earth-rock dam had strong nonlinear characteristics. The characteristic directly affected the factor of safety (FOS) of stability of dam slope and the determination of the critical slip surface. The shear strength parameter of rockfill was related to the minimum principal stress σ3 closely. And the value of σ3 had close relationship with the deformation characteristics of filling material and the process of dam filling etc. Strength reduction method has been widely used in solving the FOS of slope stability, and this method has the advantage on the searching of the critical slip surface. Combining the deformation and stress analysis of earth-rockfill dam filling process and the strength reduction method, this paper proposes a comprehensive method of dam slope stability analysis.

Based on Three-Dimensional Limit Equilibrium Slope Stability Analysis of Open Pit

As the complexity and the tall of open pit slope, two-dimensional slope stability analysis methods have been unable to meet the needs of the accuracy of stability analysis. Therefore, for the complex situation of Pingzhuang open pit slope, use with three-dimensional rigid body limit equilibrium method to analysisstability of slope.slope3D system, which consists of pre-treatment, limit equilibrium analysis solver and post-processing, the first processing core is to construct three-dimensional geological model of the slope, post-processing mainly results analysis and visualization graphics. The system combined organically the slope engineering geological information three-dimensional visualization and the analysis of stability, which make us to determine the landslide model, reveal the mechanism of landslide more accurately. Make an important contribution for ensuring safety in open pit production, a good foundation for slope stability analysis of other open pit.

Reliability Analysis on Yuwangbian Slop Based on Monte-Carlo Simulation

Based on the Yuwangbian high loess slope, which is located in Xi'an Yanta District, the basic principle of Monte-Carlo method is presented. By means of geotechnical engineering and geotechnical environment emulation software Geostudio-slope/w and based on Morgenstern-Price slope stability analysis method, the reliability and stability of the slope are analyzed under different kinds of working condition. The stability factor, reliability index and failure probability under the corresponding working conditions has been obtained. The results coincide with the actual condition, which makes the Geostudio software combine with the Monte-Carlo method and provides reference for the reliability analysis of loess slope.

강우시 습윤전선 및 지하수위를 고려한 사면의 안정성 해석

We applied a slope-stability analysis method, considering infiltration by rainfall, to the construction site where an express highway is being extended. Slope stability analysis that considers infiltration by rainfall can be classified into three methods: a method that considers the downward velocity of the wetting front, a method that considers the upward velocity of the groundwater level, and a method that considers both of these factors. The results of slope stability analysis using simplified method indicate that the safety factor due to the downward velocity of the wetting front decreases more rapidly than that due to the upward velocity of the groundwater level. For the third of the above methods, the safety factor decreases more rapidly than for the other two methods. Therefore, slope stability during rainfall should be analyzed with consideration of both the downward velocity of the wetting front and the upward velocity of the groundwater level.

다중파괴모드를 고려한 사면안정해석

최저 안전율 또는 최대 파괴확률을 기반으로 하는 기존의 사면안정해석에 대하여, 지반물성과 해석모델이 갖는 고유 불확실성을 최소화하고, 사면안정해석에서 다양한 안정해석모델과 그에 따른 파괴형상을 반영할 수 있도록 다중 파괴모드에 대한 동시 파괴확률을 고려한 사면의 신뢰성해석기법을 제안하였다. 붕괴현장조사를 통하여 현장에서 가장 빈번하게 발생하는 파괴형식을 다파괴모드로 정의하였다. 동시 파괴확률의 산정에는 체계 신뢰성해석분야에서 최근 도입된 선형계획법에 의한 최적화를 이용하였으며, 이를 통하여 여러 가지 해석모델을 신뢰성 기반으로 동시에 고려하여 해석할 수 있다. 이 방법의 적용성 평가를 위하여 기존 문헌에서 나타난 제방에 대한 신뢰성해석 결과와 비교하였다. 다중 파괴모드에 대한 동시 파괴확률을 고려한 사면의 신뢰성 해석을 적용한 결과, 전체 시스템에 대한 대한 안정성을 정량적으로 산출할 수 있음을 확인하였다. Conventional slope stability analysis is focused on calculating minimum factor of safety or maximum probability of failure. To minimize inherent uncertainty of soil properties and analytical model and to reflect various analytical models and its failure shape in slope stability analysis, slope stability analysis method considering simultaneous failure probability for multi failure mode was proposed. Linear programming recently introduced in system reliability analysis was used for calculation of simultaneous failure probability. System reliability analysis for various analytical models could be executed by this method. For application analysis for embankment, the results of this method shows that system stability of embankment calculate quantitatively.

Assessment of 3D Slope Stability Analysis Methods Based on 3D Simplified Janbu and Hovland Methods

AbstractAn assessment of three-dimensional slope stability analysis methods in terms of safety factors using several idealized sliding masses composed of plane sliding surfaces was made. Three-dimensional safety factors were calculated and compared for different study cases considered in this study on the basis of the exact solution methods, the Hovland method, and the 3D simplified Janbu method. Parameters investigated in this study included the effect of water pressure, horizontal seismic force, the changing gradient of a sliding surface, the changing lateral gradient of a sliding surface, and anchor force. Results showed that the Hovland method gives smaller safety factor values compared to the exact solutions, especially in cases of narrow failure width and high water pressure along sliding surfaces whereas the 3D simplified Janbu method gives the same safety factor values as the exact solutions

Evaluation of slope stability with topography and slope stability analysis method

In existing researches connected with landslide, natural slope was regard as a parallel slope, but it was found that many landslides were occurred on the concave and convex slopes besides parallel slopes. This study was performed to evaluate the effect of shape and length of slope and soil depth for slope stability analysis and to compare infinite slope analysis with circular failure analysis for grid by grid analysis in prediction of GIS-based landslide hazard. As grid size is increased, average slope and curvature were decreased and the decreasing tendency was prominent in mountainous areas. Comparing infinite slope analysis and circular failure analysis for various degree of slope and soil depth, safety factor by infinite slope analysis is larger than that by circular failure analysis. Result showed that the factor safety depends on the shape of slope which is composed of two continuous slopes, if grid size is small (such as 5 m×5 m). So after due consideration for soil depth and topography, proper slope stability analysis must be performed.

A state-of-the-art review of geosynthetic-reinforced slopes

Geosynthetic-reinforced slopes are generally compacted fill embankments that incorporate geosynthetic layers as tensile reinforcement to enhance stability. The reinforcement holds together the soil mass from both sides of the failure surface, thus increasing the factor of safety of the existing slope. Several analytical, numerical and experimental research works, and many case studies on geosynthetic-reinforced slopes have been reported in literature; however, no attempt has been made in recent years to give an insight into such slopes and to present an overview of these developments. This paper presents a comprehensive overview of geosynthetic-reinforced slopes, including suitability of geosynthetics, modes of failure, methods of slope stability analysis and design, model studies, and typical slope stabilization methods and some specific recommendations. The readers, especially students and practicing engineers, will find the concepts presented in this paper very useful.

Genetic algorithms in stability analysis of non-homogeneous slopes

In recent years, genetic algorithm search procedure has been used to locate the critical slip surface of homogeneous slopes. It has been found that genetic algorithm is a robust search technique which often gives global solution. In the present study, genetic algorithm has been used to locate the critical slip surface of non-homogeneous slope in conjunction with slope stability analysis method developed by Janbu (1973) for generalized slip surface. The results obtained from the present study have been compared with those available in the literature [Greco (1996) and Zolfaghari et al. (2005)]. The effect of various genetic algorithm parameters (population size, number of generations, crossover probability and mutation probability) on the solution has been studied. It has been found from the results that Janbu's method (1973) of stability analysis along with genetic algorithm as search procedure gives a better solution in terms of getting minimum factor of safety, compared to other methods.

A Modified Procedure to Evaluate Earthquake-Induced Displacement of Slopes Containing a Weak Layer

A procedure based on the Janbu method for slope stability analysis and Newmark's sliding block method for displacement calculation is proposed to evaluate rationally the earthquake-induced displacement of slopes containing a weak layer. In the procedure, the effects of the irregular geometry of the sliding plane and generation of excess pore water pressure in the weak layer which forms partly the sliding plane are considered. In the computation following the proposed procedure, a negative yield seismic coefficient to induce a safety factor of unity can be obtained because of the effect of excess pore water pressure, while the residual displacement can become a finite value because the sliding plane becomes flatter in general after the slope undergoes a large displacement.

3-dimensional slope stability analyses using non-associative stress-strain relationships

The research work presented in this paper refers to a new slope stability analysis method used for landslide risk evaluations. It is an extension of the 3-dimensional upper-bound slope stability analysis method proposed by Chen et al. in 2001, which employs the Mohr-Coulomb’s associative flow rule. It has been found that in a 3-dimensional area, a prism may not be able to move at friction angles to all its surrounding interfaces, as required by this associative rule, and convergence problems may occasionally arise. The new method establishes two velocity fields: (i) The plastic one that represents a non-associative and the best representative dilation behavior, and (ii) the virtual one that permits the solution for factor of safety in the work and energy balance equation. The new method can then allow any input value of dilation angle and thus solve the convergence problem. A practical application to a concrete dam foundation is illustrated.

A comparative slope stability analysis of New Orleans I-wall subjected to hurricane loading

There has been a relatively long history of interest in comparing the various methods of slope stability analyses in geotechnical engineering. In the past two years, mainly as a result of the damages to the Hurricane Protection System in the New Orleans, LA area and vicinity due to Hurricane Katrina, the interest in comparing a particular method of slope stability analysis with others has intensified. The Method of Planes (MOP) slope stability analysis was utilized in designing hurricane protection measures in New Orleans and vicinity. Due to unsatisfactory performance of some of the measures during Hurricane Katrina, questions were raised regarding the accuracy and suitability of the MOP slope stability analysis, which is not a total equilibrium method of analysis. Following Hurricane Katrina, an extensive investigation of the performance of floodwalls in the New Orleans area that did not perform satisfactorily, has been undertaken by the U.S. Army Corps of Engineers and others. Extensive studies have also been undertaken to assess the stability of the existing floodwalls for possible future hurricane loading. These studies included the stability investigation of cantilevered sheet pile I-walls during hurricane loading. This paper focuses on the assessment of the MOP stability analysis results for a typical New Orleans I-wall subjected to hurricane loading by comparing these results with those of other popular slope stability analysis based on a limit equilibrium approach. Comparisons between different methods of stability analyses have also been presented by considering the gap formed between the I-wall and the levee fill.

Bayesian Framework for Characterizing Geotechnical Model Uncertainty

As any model is only an abstraction of the real world, model uncertainty always exists. The magnitude of model uncertainty is important for geotechnical decision making. If model uncertainty is not considered, the geotechnical predictions and hence the decisions based on the geotechnical predictions might be biased. In this study, a framework for characterizing geotechnical model uncertainty using observation data is proposed. The framework is based on the concept of multivariable Bayesian updating, in which the statistics of model uncertainty are updated using observed performance data. Uncertainties in both input parameters and observed data can be considered in the proposed framework. To bypass complex computational works involved in the proposed framework, a practical approximate solution is presented. The proposed framework is illustrated by characterizing the model uncertainty of four limit equilibrium methods for slope stability analysis using quality centrifuge test data. Parametric study in the illustrative example shows that both quality and quantity of the performance data could affect the determination of the model uncertainty, and that such effects can be systematically quantified with the proposed method.

A more general model for the analysis of the rock slope stability

The slope stability analysis has many applications in the engineering projects such as the dams, the roads and open pits structures. The method of analysis is usually based on the equilibrium conditions of the potential plane and wedge failures. The zone of the potential failure is stable whenever the stability forces dominate instability characteristics of the slope. In most of the classic methods of slope stability analysis, the joint surfaces are assumed to be continuous along the potential failure zone. These can cause an underestimated solution to the analysis. In this research the joint trace length is considered to be discontinuous across the potential surface of failure as it happens in nature. Therefore, there exists a rock bridge between the local joint traces. Because of the numerous problems related to the rock slope stability the above assumption is satisfied and the shear strength characteristics of intact rock have taken part in the analysis. The analysis presented here gives a better concept, view, and idea of understanding the physical nature of rock slopes and includes more parameters governing the stability of the potential failure zone.

Three-Dimensional Stability Analysis of Convex Slopes in Plan View

A method of three-dimensional slope stability analysis for convex slopes in plan view is presented here based on the upper-bound theorem of the limit analysis approach. The method can also be used to determine the bearing capacity of foundations adjacent to such slopes. A rigid-block translational collapse mechanism is considered in which energy dissipation takes place along planar velocity discontinuities. Comparing the bearing capacity of foundations, numerical results indicate that the one located near convex slopes has less capacity than the one located near straight slopes. Inversely, slopes not subjected to surcharge loads are more stable when they are convex. Concerning the bearing capacity analyses, consideration of the curvature effect of convex slopes is more significant in frictional soils whereas for slope stability analyses, mentioned effect is of prime importance in cohesive soils. Numerical results of proposed algorithm are presented in the form of nondimensional graphs.

A temperature-driven strength reduction method for slope stability analysis

This paper presents a new technique in strength reduction associated with finite element method for slope stability analysis. Cohesions and internal friction angles of soils are assigned as functions of temperature and used in strength reduction by changing nodal temperatures, so that the process of finding a factor of safety is transferred to the solution of a conventional thermal loading problem. The safety factor of a slope can be achieved in a single simulation process, without repeating the trial calculation. The increment of the thermal loading can also be automatically adjusted so as to accelerate the solving process.

Displacement based multiple wedge slope stability analysis

A method of slope stability analysis based upon multiple wedges is developed, accounting for kinematics in a similar way to proposals by [Srbulov M. On the influence of soil strength brittleness and nonlinearity on slope stability. Comput Geotech 1997;20(1):95--104] and [Donald IB, Chen Z. Modern wedge methods of slope analysis – their power and their versatility. In: Second international conference on landslides, slope stability & the safety of infra-structures; 1999. p. 13–24]. Instead of relying on almost arbitrary assumptions about stresses on wedge or slice boundaries to demonstrate an equilibrium of both forces and moments, the method works from simple assumptions about the kinematics of movement, increasing displacements and hence resisting forces iteratively until force equilibrium is attained. The procedure is simple and efficient, and ensures that inter-wedge forces developed by the movement are consistent with the shape of the sliding surface.