scholarly journals Evaluation of the stability of anchor-reinforced slopes

2005 ◽  
Vol 42 (5) ◽  
pp. 1342-1349 ◽  
Author(s):  
D Y Zhu ◽  
C F Lee ◽  
D H Chan ◽  
H D Jiang
Keyword(s):  
Stress Distribution ◽  
Normal Stress ◽  
Factor Of Safety ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Load Factor ◽  
Normal Stress Distribution ◽  
Abrupt Changes ◽  
Reinforced Slopes ◽  
The Stability

The conventional methods of slices are commonly used for the analysis of slope stability. When anchor loads are involved, they are often treated as point loads, which may lead to abrupt changes in the normal stress distribution on the potential slip surface. As such abrupt changes are not reasonable and do not reflect reality in the field, an alternative approach based on the limit equilibrium principle is proposed for the evaluation of the stability of anchor-reinforced slopes. With this approach, the normal stress distribution over the slip surface before the application of the anchor (i.e., σ0) is computed by the conventional, rigorous methods of slices, and the normal stress on the slip surface purely induced by the anchor load (i.e., λpσp, where λp is the load factor) is taken as the analytical elastic stress distribution in an infinite wedge approximating the slope geometry, with the anchor load acting on the apex. Then the normal stress on the slip surface for the anchor-reinforced slope is assumed to be the linear combination of these two normal stresses involving two auxiliary unknowns, η1 and η2; that is, σ = η1σ0 + η2λpσp. Simultaneously solving the horizontal force, the vertical force, and the moment equilibrium equations for the sliding body leads to the explicit expression for the factor of safety (Fs)—or the load factor (λp), if the required factor of safety is prescribed. The reasonableness and advantages of the present method in comparison with the conventional procedures are demonstrated with two illustrative examples. The proposed procedure can be readily applied to designs of excavated slopes or remediation of landslides with steel anchors or prestressed cables, as well as with soil nails or geotextile reinforcements.Key words: slopes, factor of safety, anchors, limit equilibrium method.

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.

scholarly journals Measuring the Normal Stress Distribution Acting on a Locked-Wheel of Push–Pull Locomotion Rovers via a Wheel Sensor System

Sensors ◽  
2020 ◽  
Vol 20 (16) ◽  
pp. 4434
Author(s):  
Daisuke Fujiwara ◽  
Tetsuya Oshima ◽  
Kojiro Iizuka
Keyword(s):  
Stress Distribution ◽  
Normal Stress ◽  
Contact Area ◽  
Slip Surface ◽  
Tangential Force ◽  
Measured Data ◽  
Sensor System ◽  
Resistance Force ◽  
Normal Stress Distribution ◽  
Wheel Sensor

The resistance force generated when the locked-wheel acts on the soil is critical for deciding the traveling performance of push–pull locomotion. The resistance force depends on the tangential force of the sliding soil wedge beneath the wheel, and the tangential force depends on the forces of the soil and the wheel perpendicular to the tangential direction. Hence, the normal stress distribution of the locked-wheel can affect the resistance force. Previous studies indicated different insights that describe either a uniform or non-uniform shape of the normal stress distribution. The distribution of the locked-wheel still needs to be examined experimentally. This study measured the normal stress distribution using the wheel sensor system, and the variation of the contact area and slip surface beneath the wheel were also observed in PIV analysis. Those results showed that the normal stress distribution was non-uniform along the wheel contact area, and the change of the distribution was confirmed with the change of the contact area and slip surface. Then, the resistance force calculated by a preliminary model based on the measured data was compared with the total resistance force of the wheel measured by a separate sensor. This comparison provided a theoretical consideration for the measured data.

Three-dimensional slope stability based on stresses from a stress-deformation analysis

2011 ◽  
Vol 48 (6) ◽  
pp. 891-904 ◽  
Author(s):  
J.R. Stianson ◽  
D.G. Fredlund ◽  
D. Chan
Keyword(s):  
Stress Distribution ◽  
Slope Stability ◽  
Internal Stress ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Three Dimensional ◽  
Equilibrium Analysis ◽  
Deformation Analysis ◽  
Stress Deformation ◽  
The Stability

A procedure is developed where stresses from a finite element analysis are incorporated into a limit equilibrium framework to evaluate the stability of three-dimensional slopes. An independent stress-deformation analysis is performed to calculate the internal stress state for the slope. The stress distribution is imported into the three-dimensional slope stability analysis in the form of a regular grid. The slip surfaces considered in the limit equilibrium analysis are ellipsoidal and discretized using a series of triangular planes. The normal and shear force acting at the centroid of individual triangular planes can be computed from the internal stress distribution. Subsequently, the factor of safety of a selected slip surface can be calculated directly without using an iterative procedure. A series of verification examples are presented to confirm that the proposed method provides the required accuracy and flexibility to assess the stability of slopes typically encountered in practice. Sensitivity analyses are presented to show how the procedure used to compute the forces acting on each triangular plane, the number of planes used to discretize the slip surface, and Poisson’s ratio influence the computed factors of safety, but do not limit the successful application of the methodology.

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.

Analytical Method of Calculating Slope Stability by Elasticity Theory and Limit Equilibrium Method

2012 ◽  
Vol 170-173 ◽  
pp. 1167-1173
Author(s):  
Ai Zhong Lu ◽  
Ning Zhang
Keyword(s):  
Stress Distribution ◽  
Slope Stability ◽  
Elastic Stress ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Limit Equilibrium Method ◽  
Normal Stress Distribution ◽  
Clear Physical Meaning ◽  
Equilibrium Method ◽  
Coulomb Criterion

In this paper, the slope before failure is considered as an elastic body subjected to gravity only. With known stress distribution in the slope, stability analysis is carried out by the limit equilibrium method according to the Mohr-Coulomb criterion satisfied by the slip plane. The method proposed in this paper is different from the previous methods, as there is no need to divide the slope into vertical elements or to assume the normal stress distribution on the slip surface. Instead, the solutions are found by directly using the elastic stress solutions in the slope. The equations derived are straightforward and most of them are explicit expressions, which facilitate analyses on the effects of mechanical properties and geometric parameters on the slope stability. This method has clear physical meaning and few assumptions are made.

scholarly journals The Influence of Initial Normal Stress Assumption of Slip Surface on Safety Factor of Symmetrical Three-Dimensional Slopes

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Huali Liu
Keyword(s):  
Stress Distribution ◽  
Normal Stress ◽  
Safety Factor ◽  
Slip Surface ◽  
Three Dimensional ◽  
Normal Stresses ◽  
Equilibrium Conditions ◽  
Normal Stress Distribution ◽  
A Value ◽  
Force Equilibrium

By using the explicit solution of three-dimensional slope stability based on modification of normal stress distribution over the slip surface, the influence of assumption of the three-dimensional initial normal stress on the safety factor is investigated. The initial normal stress distribution over the 3D slip surface was assumed, and then it was modified by a function with 2 parameters to satisfy two force equilibrium conditions about two axes and one moment equilibrium condition around one axis. An iterative equation was derived that would yield a value to 3D safety factor. The values of three-dimensional safety factor of symmetrical slopes are computed with different assumptions of initial normal stresses. The computation results show that the influence of assumption of initial normal stress on the safety factor of symmetrical three-dimensional slopes is negligible because the maximum different value of the three-dimensional safety factor is below 5%.

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.

Stress in Bonded Adherends for Single Lap Joints

1996 ◽  
Vol 12 (03) ◽  
pp. 167-171
Author(s):  
G. Bezine ◽  
A. Roy ◽  
A. Vinet
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Numerical Model ◽  
Stress Distribution ◽  
Normal Stress ◽  
Lap Joints ◽  
Axial Loads ◽  
Normal Stress Distribution ◽  
Single Lap Joints ◽  
Element Technique

A finite-element technique is used to predict the shear stress and normal stress distribution in adherends for polycarbonate/polycarbonate single lap joints subjected to axial loads. Numerical and photoelastic results are compared so that a validation of the numerical model is obtained. The influences on stresses of the overlap length and the shape of the adherends are studied.

Some difficulties associated with the limit equilibrium method of slices

1983 ◽  
Vol 20 (4) ◽  
pp. 661-672 ◽  
Author(s):  
R. K. H. Ching ◽  
D. G. Fredlund
Keyword(s):  
Slope Stability ◽  
Factor Of Safety ◽  
Limit Equilibrium ◽  
Stability Limit ◽  
Limit Equilibrium Method ◽  
Soil Conditions ◽  
Side Force ◽  
Limit Equilibrium Methods ◽  
Equilibrium Method ◽  
The Stability

Several commonly encountered problems associated with the limit equilibrium methods of slices are discussed. These problems are primarily related to the assumptions used to render the inherently indeterminate analysis determinate. When these problems occur in the stability computations, unreasonable solutions are often obtained. It appears that problems occur mainly in situations where the assumption to render the analysis determinate seriously departs from realistic soil conditions. These problems should not, in general, discourage the use of the method of slices. Example problems are presented to illustrate these difficulties and suggestions are proposed to resolve these problems. Keywords: slope stability, limit equilibrium, method of slices, factor of safety, side force function.

Normal stress distribution adjacent to optimum holes in composite plates

1994 ◽  
Vol 29 (4) ◽  
pp. 393-398 ◽  
Author(s):  
R. Ramesh Kumar ◽  
G. Venkateswara Rao ◽  
K.S. Suresh
Keyword(s):  
Stress Distribution ◽  
Normal Stress ◽  
Composite Plates ◽  
Normal Stress Distribution
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