Analysis of a rock slope with internal dilation

1984 ◽  
Vol 21 (4) ◽  
pp. 605-620 ◽  
Author(s):  
C. D. Martin ◽  
P. K. Kaiser
Keyword(s):  
Failure Mechanism ◽  
Rock Slope ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Three Dimensional ◽  
Back Analysis ◽  
Hydroelectric Project ◽  
Limit Equilibrium Methods ◽  
Slide Mass ◽  
Stability Of Slopes

A class of rock slope failures exists in which the mode of failure requires the existence or creation of internal shears to accommodate large internal slide mass distortion. These internal displacements are required to allow motion along the basal slip surface. This paper demonstrates that the more traditional limit equilibrium methods of analysis are often conservative when used to assess the stability of slopes with this failure mechanism. As a result, back analysis may overestimate the available shear resistance. A method of analysis capable of handling this failure mechanism was proposed by S. K. Sarma. A case history from the Revelstoke Hydroelectric Project, British Columbia, is used to demonstrate that these internal shears were required for movement to occur and that passive anchors inside the sliding rock mass can be used to improve the overall slope stability. No attempt is made to evaluate the actual factor of safety of the three-dimensional slide mass. Key words: rock slope, foliation shear, stability analysis, dilation, internal shears, passive anchors.

A 3D slope stability analysis method assuming parallel lines of intersection and differential straining of block contacts

2002 ◽  
Vol 39 (4) ◽  
pp. 799-811 ◽  
Author(s):  
Muhsiung Chang
Keyword(s):  
Slope Stability ◽  
Factor Of Safety ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Three Dimensional ◽  
Shear Stresses ◽  
Block System ◽  
Stability Of Slopes ◽  
Sliding Mechanism ◽  
The Stability

A three-dimensional (3D) method of analysis of the stability of slopes was developed based on the sliding mechanism observed in the 1988 failure of the Kettleman Hills landfill slope (Kettleman City, California) and the associated model studies. By adopting a limit equilibrium concept, the method assumes the sliding mass as a block system in which the contacts between blocks are inclined. The lines of intersection of the block contacts are assumed to be parallel, which enables the sliding kinematics. In consideration of the differential straining between blocks, the shear stresses on the slip surface and the block contacts are evaluated based on the degree of shear strength mobilization on these contacts. The overall factor of safety is calculated based on the force equilibrium of the individual blocks and the entire block system as well. Based on comparisons with a series of hypothetical 3D and 2D problems with known solutions, the method was generally found to be accurate in predicting the stability of slopes involving a translational type of sliding failure. For rotational sliding failures in clays, however, the method appears to slightly overestimate the calculated factor of safety; up to as much as 10% in a typical problem examined in this study.Key words: slope stability, 3D method, limit equilibrium, block kinematics, strain incompatibility.

The 2001 R.M. Hardy Lecture: The limits of limit equilibrium analyses

2003 ◽  
Vol 40 (3) ◽  
pp. 643-660 ◽  
Author(s):  
John Krahn
Keyword(s):  
Finite Element ◽  
Factor Of Safety ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Geotechnical Engineering ◽  
Software Tools ◽  
Great Promise ◽  
Engineering Practice ◽  
Stability Factor ◽  
Limit Equilibrium Methods

Limit equilibrium types of analysis have been in use in geotechnical engineering for a long time and are now used routinely in geotechnical engineering practice. Modern graphical software tools have made it possible to gain a much better understanding of the inner numerical details of the method. A closer look at the details reveals that the limit equilibrium method of slices has some serious limitations. The fundamental shortcoming of limit equilibrium methods, which only satisfy equations of statics, is that they do not consider strain and displacement compatibility. This limitation can be overcome by using finite element computed stresses inside a conventional limit equilibrium framework. From the finite element stresses both the total shear resistance and the total mobilized shear stress on a slip surface can be computed and used to determine the factor of safety. Software tools that make this feasible and practical are now available, and they hold great promise for advancing the technology of analyzing the stability of earth structures.Key words: limit equilibrium, stability, factor of safety, finite element, ground stresses, slip surface.

Determination of three-dimensional shape of failure in soil slopes

2015 ◽  
Vol 52 (9) ◽  
pp. 1283-1301 ◽  
Author(s):  
Roohollah Kalatehjari ◽  
Ali Arefnia ◽  
Ahmad Safuan A Rashid ◽  
Nazri Ali ◽  
Mohsen Hajihassani
Keyword(s):  
Slope Stability ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Three Dimensional ◽  
Failure Surface ◽  
Small Scale ◽  
3D Shape ◽  
Finite Element Software ◽  
Soil Slopes ◽  
3D Slope Stability

This paper presents the application of particle swarm optimization (PSO) in three-dimensional (3D) slope stability analysis to determine the shape and direction of failure as the critical slip surface. A detailed description of adopted PSO is presented and a rotating ellipsoidal shape is introduced as the possible failure surface in the analysis. Based on the limit equilibrium method, an equation of factor of safety (FoS) was developed with the ability to calculate the direction of sliding (DoS) in its internal process. A computer code was developed in Matlab to determine the 3D shape of the failure surface and calculate its FoS and DoS. Then, two example problems were used to verify the applicability of the presented code, the first by conducting a comparison between the results of the code and PLAXIS-3D finite element software and the second by re-analyzing an example from the literature to find the 3D failure surface. In addition, a hypothetical 3D asymmetric slope was introduced and analyzed to demonstrate the ability of the presented method to determine the shape and DOS of failure in 3D slope stability problems. Finally, a small-scale physical model of a 3D slope under vertical load was constructed and tested in the laboratory and the results were re-analyzed and compared with the code results. The results demonstrate the efficiency and effectiveness of the presented code in determining the 3D shape of the failure surface in soil slopes.

A Comparative Study on Locating Critical Slip Surface in 2D and 3D Limit Equilibrium Stability Analysis of Slopes

2012 ◽  
Vol 446-449 ◽  
pp. 1905-1913
Author(s):  
Mo Wen Xie ◽  
Zeng Fu Wang ◽  
Xiang Yu Liu ◽  
Ning Jia
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Safety Factor ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Three Dimensional ◽  
Slope Stability Analysis ◽  
Equilibrium Stability ◽  
Critical Slip Surface ◽  
Minimum Safety Factor

The Various methods of optimization or random search have been developed for locating the critical slip surface of a slope and the related minimum safety factor in the limit equilibrium stability analysis of slope. But all these methods are based on a two-dimensional (2D) method and no one had been adapted for a search of the three-dimensional (3D) critical slip surface. In this paper, a new Monte Carlo random simulating method has been proposed to identify the 3D critical slip surface, in which assuming the initial slip to be the lower part of an ellipsoid, the 3D critical slip surface in the 3D slope stability analysis is located by minimizing the 3D safety factor of limit equilibrium approach. Based on the column-based three-dimensional limit equilibrium slope stability analysis models, new Geographic Information Systems (GIS) grid-based 3D deterministic limit equilibrium models are developed to calculate the 3D safety factors. Several practical examples, of obtained minimum safety factor and its critical slip surface by a 2D optimization or random technique, are extended to 3D slope problems to locate the 3D critical slip surface and to compare with the 2D results. The results shows that, comparing with the 2D results, the resulting 3D critical slip surface has no apparent difference only from a cross section, but the associated 3D safety factor is definitely higher.

The application of dynamic programming to slope stability analysis

2003 ◽  
Vol 40 (4) ◽  
pp. 830-847 ◽  
Author(s):  
Ha T.V Pham ◽  
Delwyn G Fredlund
Keyword(s):  
Dynamic Programming ◽  
Slope Stability ◽  
Stress Analysis ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Programming Method ◽  
Dynamic Programming Method ◽  
Critical Slip Surface ◽  
Limit Equilibrium Methods ◽  
Conventional Limit

The applicability of the dynamic programming method to two-dimensional slope stability analyses is studied. The critical slip surface is defined as the slip surface that yields the minimum value of an optimal function. The only assumption regarding the shape of the critical slip surface is that the surface is an assemblage of linear segments. Stresses acting along the critical slip surface are computed using a finite element stress analysis. Assumptions associated with limit equilibrium methods of slices related to the shape of the critical slip surface and the relationship between interslice forces are no longer required. A computer program named DYNPROG was developed based on the proposed analytical procedure, and numerous example problems have been analyzed. Results obtained when using DYNPROG were compared with those obtained when using several well-known limit equilibrium methods. The comparisons demonstrate that the dynamic programming method provides a superior solution when compared with conventional limit equilibrium methods. Analyses conducted also show that factors of safety computed when using the dynamic programming method are generally slightly lower than those computed using conventional limit equilibrium methods of slices; however, as Poisson's ratio approaches 0.5, the computed factors of safety from the dynamic programming method and the limit equilibrium method appear to become similar.Key words: dynamic programming, slope stability, stress analysis, optimization theory, limit equilibrium methods of slices.

scholarly journals Strain-dependent slope stability

2020 ◽  
Vol 15 (11) ◽  
pp. 3111-3119
Author(s):  
Kornelia Nitzsche ◽  
Ivo Herle
Keyword(s):  
Slope Stability ◽  
Failure Modes ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Shear Stresses ◽  
Safety Factors ◽  
Limit Equilibrium Methods ◽  
Hydraulic Conditions ◽  
Stress States ◽  
Strain Dependent

Abstract The state of equilibrium of a slope is usually interpreted and expressed by safety factors based on calculations with limit equilibrium methods. Different stress states, failure modes and hydraulic conditions in sections along a slip surface affect the development of shear stresses during slope movement. Moreover, a post-peak softening of the shear strength can have a pronounced impact. As a consequence of the latter effect, the mobilization of the shear resistance along the slip surface is non-uniform and the safety of the slope can be overestimated or underestimated. In the presented paper, an algorithm is proposed to capture the strain-dependent slope stability. The approach is illustrated by means of a calculation example for a slope with a planar slip surface where a block sliding is assumed.

Revisiting the three-dimensional slope stability problem in clay

2012 ◽  
Vol 49 (4) ◽  
pp. 494-498 ◽  
Author(s):  
Fei Cai ◽  
Atsushi Nakamura ◽  
Keizo Ugai
Keyword(s):  
Safety Factor ◽  
Stability Problem ◽  
Limit Equilibrium ◽  
Three Dimensional ◽  
Failure Surface ◽  
Benchmark Problem ◽  
Integral Expression ◽  
Equilibrium Conditions ◽  
Limit Equilibrium Methods ◽  
Force Equilibrium

This note revisits the benchmark problem involving a spherical failure surface in clay, gives an integral expression for the safety factor defined in terms of moments, and points out the mistakes in the solution of Silvestri. An integral expression for the safety factor of three-dimensional simplified Janbu’s method is also presented to facilitate the validation of three-dimensional limit equilibrium methods that satisfy force equilibrium conditions.

Anti-Sliding Stability Analysis of Saturated Rock Slope

2013 ◽  
Vol 405-408 ◽  
pp. 294-298
Author(s):  
Wei Luo ◽  
Jia Qi Chen ◽  
Lian Heng Zhao ◽  
Pan Cheng
Keyword(s):  
Rock Slope ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Seismic Load ◽  
Stability Factor ◽  
Surface Drag ◽  
Groundwater Levels ◽  
Saturated Rock ◽  
Sliding Stability ◽  
Water Saturated

Based on the assumption of the improved groundwater pressure distribution, the calculation expression of anti-sliding stability factor for typical water-saturated rock slope is deduced through limit equilibrium method. Considering the combined effect of slope overload, seismic load, anchoring effect, ice frost, slip surface drag force and slope groundwater pressure, the comparative analysis of typical rock slope sliding stability under waterless and saturated conditions shows that, the outflow joint blocking and the groundwater levels rising have obvious adverse effects on the anti-sliding stability of rock slope. Figures about the relationship of stability factors and geometric factors were drawn and the anti-sliding stability factor can be directly obtained from these figures. All would be the references for the similar engineering projects.

Study of the Three-Dimensional Global Limit Equilibrium Method Applied to the Stability of Rock Slope

2012 ◽  
Vol 249-250 ◽  
pp. 1099-1102
Author(s):  
Yi Sheng Huang ◽  
Jian Lin Li
Keyword(s):  
Rock Mass ◽  
Stability Analysis ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Limit State ◽  
Three Dimensional ◽  
Limit Equilibrium Method ◽  
Equilibrium Method ◽  
The Stability ◽  
Loose Rock

Amending the normal stress over the slip surface based on the stress field by numerical analysis, applying the three-dimensional global limit equilibrium method to the stability analysis of tension-slackened rock mass in the right bank of Yagen hydropower station. Stability analysis shows that if do not take any measures, the loose rock mass stability can cater to the Specification demand, but some small sliders is in the limit state under the water and earthquake condition, if use the cutting slope and unloading scheme, the whole loose rock mass and the all small sliders can meet the Specification standard stability requirements.

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