Search for critical slip surfaces based on finite element method

1995 ◽  
Vol 32 (2) ◽  
pp. 233-246 ◽  
Author(s):  
Jin-Zhang Zou ◽  
David J. Williams ◽  
Wen-Lin Xiong
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Dynamic Programming ◽  
Factor Of Safety ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Dynamic Programming Method ◽  
Critical Slip Surface ◽  
Slip Surfaces ◽  
Element Method

In this paper, finite element methods (FEM) are used to determine local shear strength mobilization ratios within a slope and to indicate the probable location of the critical slip surface. To locate the critical slip surface and hence determine the minimum factor of safety, an improved dynamic programming method (IDPM) is employed, in which possible slip surfaces, which must pass between state points, may pass both between and along stages. The IDPM is coupled with an expression for the factor of safety for which the stresses are obtained from the FEM. The results obtained using the FEM–IDPM, for a homogeneous slope and for a test embankment on soft Bangkok clay, have been compared with those observed and obtained using the traditional finite element method and the generalized limit equilibrium wedge method. The FEM–IDPM has the advantage over limit equilibrium methods that the strain- and time-dependent behaviour of soil and the staged construction of the slope can be modelled. Key words : critical slip surface, dynamic programming, factor of safety, finite element method, limit equilibrium method, slope stability.

Landslide Simulation Using Limit Equilibrium and Finite Element Method

2016 ◽  
Vol 857 ◽  
pp. 555-559 ◽  
Author(s):  
Zuhayr Md Ghazaly ◽  
Mustaqqim Abdul Rahim ◽  
Kok Alfred Chee Jee ◽  
Nur Fitriah Isa ◽  
Liyana Ahmad Sofri
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Factor Of Safety ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Main Concern ◽  
Analysis Method ◽  
Stability Of Slope ◽  
The Stability ◽  
Element Method

Slope stability analysis is one of the ancient tasks in the geotechnical engineering. There are two major methods; limit equilibrium method (LEM) and finite element method (FEM) that were used to analyze the factor of safety (FOS) to determine the stability of slope. The factor of safety will affect the remediation method to be underdesign or overdesign if the analysis method was not well chosen. This can lead to safety and costing problems which are the main concern. Furthermore, there were no statement that issued one of the analysis methods was more preferred than another. To achieve the objective of this research, the soil sample collected from landslide at Wang Kelian were tested to obtain the parameters of the soils. Then, those results were inserted into Plaxis and Slope/W software for modeling to obtain the factor of safety based on different cases such as geometry and homogenous of slope. The FOS obtained by FEM was generally lower compared to LEM but LEM can provide an obvious critical slip surface. This can be explained by their principles. Overall, the analysis method chosen must be based on the purpose of the analysis.

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.

Landslide Stability Analysis Based on GeoStudio

2013 ◽  
Vol 634-638 ◽  
pp. 3701-3704 ◽  
Author(s):  
Rui Wang ◽  
Xi Wang ◽  
Kun Yin ◽  
Yang Zhao
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stability Analysis ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Limit Equilibrium Method ◽  
Sliding Surface ◽  
Landslide Stability ◽  
Equilibrium Method ◽  
Element Method

In order to monitor landslide risk, GeoStudio software is frequently applied to landslide stability analysis. In this paper, Juting landslide in Shanxi was subjected by GeoStudio software, while limit equilibrium method was adopted to calculate the landslide stability in the slip surface. The solutions of stress and displacement vector were gotten through SIGMA / W module on the landslide for finite element method in sliding surface stress analysis. And it was also used to import the results obtained in SIGMA / W module into SLOPE / W module to calculate safety factor and the potential sliding surface. The result shows that the calculated safety factors which are worked out by those two ways are close to each other, and limit equilibrium method can be used in landslide stability analysis, but the finite element method is more consistent with the actual situation. GeoStudio software can calculate landslide stability coefficient conveniently, and can express potential slip surface intuitively, providing reliable foundation for landslide stability analysis.

Convergence aspect of limit equilibrium methods for slopes

1990 ◽  
Vol 27 (1) ◽  
pp. 145-151 ◽  
Author(s):  
R. N. Chowdhury ◽  
S. Zhang
Keyword(s):  
Factor Of Safety ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Solution Process ◽  
Iterative Solution ◽  
Friction Angle ◽  
Equilibrium Analysis ◽  
Negative Slope ◽  
Slip Surfaces ◽  
Geological Discontinuity

This note is concerned with the multiplicity of solutions for the factor of safety that may be obtained on the basis of the method of slices. Discontinuities in the function for the factor of safety are discussed and the reasons for false convergence in any iterative solution process are explored, with particular reference to the well-known Bishop simplified method (circular slip surfaces) and Janbu simplified or generalized method (slip surfaces of arbitrary shape). The note emphasizes that both the solution method and the method of searching for the critical slip surface must be considered in assessing the potential for numerical difficulties and false convergence. Direct search methods for optimization (e.g., the simplex reflection method) appear to be superior to the grid search or repeated trial methods in this respect. To avoid false convergence, the initially assumed value of factor of safety F0 should be greater than β1(=−tan α1 tan [Formula: see text]) where α1 and [Formula: see text] are respectively the base inclination and internal friction angle of the first slice near the toe of a slope, the slice with the largest negative reverse inclination. A value of F0 = 1 + β1, is recommended on the basis of experience. If there is no slice with a negative slope for any of the slip surfaces generated in the automatic, search process, then any positive value of F0 will lead to true convergence for F. It is necessary to emphasize that no slip surface needs to be rejected for computational reasons except for Sarma's methods and similarly no artificial changes need to be made to the value of [Formula: see text] except for Sarma's methods. Key words: slope stability, convergence, limit equilibrium, analysis, optimization, slip surfaces, geological discontinuity, simplex reflection technique.

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.

Stability Analysis of Soil Slope and the Design of Anti-Slide Piles during Unsteady Seepage

2012 ◽  
Vol 204-208 ◽  
pp. 689-693
Author(s):  
Yong Quan Li ◽  
Hang Jing ◽  
Qing Huan Wang ◽  
Jun Fu Chen
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Limit Equilibrium ◽  
Limit Equilibrium Method ◽  
Engineering Practice ◽  
Soil Slope ◽  
Safety Factors ◽  
Seepage Analysis ◽  
Slip Surfaces ◽  
Earth Pressures

Principle of calculation of water and earth pressures together by Limit Equilibrium Method (LEM) is introduced, and coupled deformation and seepage analysis is conducted by Finite Element Method (FEM ).The response of one soil slope is simulated during rapid drawdown of water level by LEM and FEM. The results calculated show that seepage upraises the critical slip surfaces, and critical slip surfaces and safety factors by two ways are pretty close. To assure the safety of the slope, the design of anti-slide piles is carried out. Those ways used may provide reference to engineering practice.

Links between the Factor-of-Safety and the Reliability Methods of Design

1993 ◽  
Vol 21 (4) ◽  
pp. 309-315
Author(s):  
Michael A. Latcha ◽  
Joseph Der Hovanesian
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Factor Of Safety ◽  
Mechanical Design ◽  
Stochastic Method ◽  
The Finite Element Method ◽  
Design Reliability ◽  
Reliability Methods ◽  
Stochastic Data ◽  
Element Method

Relationships are developed that bridge the gap between the deterministic, or factor-of-safety, approach to mechanical design and the more recent reliability, or stochastic, method. The resulting equations make it possible to incorporate stochastic data into determìnistic analyses, such as the finite element method. Estimates of design reliability can be calculated, based on the variation of the strength of the material and/or the stresses seen by the part while in service.

Slope Stability Analysis of Jiu-Fen Using Finite Element Method and Limit Equilibrium Method

2012 ◽  
Vol 170-173 ◽  
pp. 1064-1067
Author(s):  
Shong Loong Chen ◽  
Chun Fu Lin
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Slope Stability ◽  
Displacement Vector ◽  
Limit Equilibrium ◽  
Limit Equilibrium Method ◽  
The Finite Element Method ◽  
Safety Factors ◽  
Equilibrium Method ◽  
Element Method

This study simulates the slope stability at Jiu-Fen, using the limit equilibrium method and the finite element method. The limit equilibrium method can find potential slide surfaces and safety factors rapidly. The advantage of the finite element method is that it utilizes more reasonable soil behavior and boundary conditions. A critical slide surface obtained by the limit equilibrium method can be compared with the displacement vector, stress field and location of plastic zone obtained by the finite element method. Furthermore, we can compare the safety factors produced by the two methods. This study shows that the safety factor from the limit equilibrium method is higher than that from the finite element method. The displacement analysis by the finite element method agrees well with the progressive slope failure. So, if we combine the two methods using monitored data in the field, we can analyze slope stability clearly.

Stability Analyses of Western Slopes in Jointed Rock Masses for GuangYang Highway

2011 ◽  
Vol 368-373 ◽  
pp. 234-240
Author(s):  
Shu Li Wang ◽  
Man Gen Mu ◽  
Ran Wang ◽  
Wen Bo Cui
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Limit Equilibrium ◽  
Western Slope ◽  
Seismic Load ◽  
The Finite Element Method ◽  
Element Analysis ◽  
Limit Equilibrium Methods ◽  
The Stability ◽  
Element Method

This paper presents the results of a study on a joint slope deformation affecting the western slope of the GuangYang highway (YangQuan, China). Fieldwork identified the ongoing deformational process and assisted in defining its mechanisms, evolution and controlling factors. Here we discuss how to use limit equilibrium methods to calculate the behavior of slopes and to use the finite element analysis to evaluate the stability, displacements of slopes and soil-slope stabilization interaction. The finite element method with shear strength reduction (SSR) technique is explained in Phase2D. This method is effective for the prediction of the stability of slope. Based on numerical comparisons between the limit equilibrium methods and finite element method, it is suggested that the finite element method with SSR technique is a reliable and maybe unique approach to evaluate the slope stability. The paper also took into account effectiveness of the large rain and seismic load. The results of the numerical analysis are consistent with the observed slope surface evidence.

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