scholarly journals ANALYSIS OF EARTH FILL HYDRAULIC DAM WITH VARYING CREST LENGTH AND PERMEABILITY TO DEVELOP CORRELATIONS

2020 ◽  
Vol 4 (2) ◽  
pp. 34-38
Author(s):  
Muhammad Israr Khan ◽  
Shuhong Wang ◽  
Zhangze .
Keyword(s):  
Finite Element ◽  
Shear Strength ◽  
Factor Of Safety ◽  
Limit Equilibrium ◽  
Stable Condition ◽  
Internal Erosion ◽  
Earthen Dam ◽  
Soil Layers ◽  
Crest Length ◽  
Earth Fill

In this paper, an earthen dam is analysed using different soil layers having different soil properties and dimensions. Normally a slope fail when the shear strength reduces from the minimum required value which keeps it stable. Internal erosion is the main cause which causes a dam to fail and it is mainly due seepage with time. A detail analysis of a predefined dam slope is performed in different layers to check the seepage variation as well as the factor of safety. Different soil layers and properties were used such that it is investigated from a fail condition to a complete stable condition. Limit equilibrium and finite element approaches are used. Correlations for factor of safety between these two approaches are also developed. These correlations and results could be used as guidelines in any dam or slope safety calculation.

Progressive failure of the Carsington Dam: a numerical study

1992 ◽  
Vol 29 (6) ◽  
pp. 971-988 ◽  
Author(s):  
Z. Chen ◽  
N. R. Morgenstern ◽  
D. H. Chan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Factor Of Safety ◽  
Progressive Failure ◽  
Limit Equilibrium ◽  
Equilibrium Analysis ◽  
Element Analysis ◽  
Limit Equilibrium Analysis ◽  
The Finite Element Analysis ◽  
Yellow Clay

The mechanism of progressive failure is well understood as one which involves nonuniform straining of a strain-weakening material. Traditional limit equilibrium analysis cannot be used alone to obtain a rational solution for progressive failure problems because the deformation of the structure must be taken into account in the analysis. The failure of the Carsington Dam during construction in 1984 has been attributed to progressive failure of the underlying yellow clay and the dam core materials. The dam was monitored extensively prior to failure, and an elaborate geotechnical investigation was undertaken after failure. The limit equilibrium analysis indicated that the factors of safety were over 1.4 using peak strength of intact clay material or 1.2 based on reduced strength accounting for preshearing of the yellow clay layer. Factors of safety were found to be less than unity if residual strengths were used. The actual factor of safety at failure was, of course, equal to one. By using the finite element analysis with strain-weakening models, the extent and degree of weakening along the potential slip surface were calculated. The calculated shear strength was then used in the limit equilibrium analysis, and the factor of safety was found to be 1.05, which is very close to the actual value of 1.0. More importantly, the mechanism of failure and the initiation and propagation of the shear zones were captured in the finite element analysis. It was also found that accounting explicitly for pore-water pressure effects using the effective stress approach in the finite element and limit equilibrium analyses provides more realistic simulations of the failure process of the structure than analyses based on total stresses. Key words : progressive failure, strain softening, finite element analysis, dams.

Factor of safety of slope stability from deformation energy

2018 ◽  
Vol 55 (2) ◽  
pp. 296-302 ◽  
Author(s):  
Shiguo Xiao ◽  
Wei Dong Guo ◽  
Jinxiu Zeng
Keyword(s):  
Shear Strength ◽  
Factor Of Safety ◽  
Plastic Material ◽  
Limit Equilibrium ◽  
Deformation Energy ◽  
Simple Expression ◽  
Shear Stresses ◽  
Limit Equilibrium Methods ◽  
Coulomb Failure Criterion ◽  
Elastic Plastic Material

The factor of safety of a slope (Fs) is invariably assessed using methods underpinned by moment, force, and (or) shear strength equilibrium concerning slip surfaces. Each method inherently embeds some form of limitations, despite being popularly adopted in practice. In this paper, a new Fs is devised using the ratio of ultimate energy (eu, upon sliding) over accumulated “elastic” energy. The Fs is then reduced to a simple expression of the power to shear stress and shear strength, by taking soil as an elastic–plastic material obeying the Mohr–Coulomb failure criterion. This expression empowers significant efficacy in gaining the factor of safety (without involving energy or directions of shear stresses). The Fs values were calculated for three typical slopes concerning various mechanical properties (dilation, Poisson’s ratio, and shear modulus) and effective computational strategies. All of the Fs values (to a congruous accuracy of available methods) were obtained in less than 1% the time of conventional numerical analyses. The proposed Fs, equally applicable to limit equilibrium methods, may be utilized in practice to expedite slope design.

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 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.

scholarly journals Particle Swarm Optimization Algorithm Coupled with Finite Element Limit Equilibrium Method for Geotechnical Practices

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Hongjun Li ◽  
Hong Zhong ◽  
Zuwen Yan ◽  
Xuedong Zhang
Keyword(s):  
Finite Element ◽  
Particle Swarm Optimization ◽  
Optimization Algorithm ◽  
Factor Of Safety ◽  
Particle Swarm Optimization Algorithm ◽  
Limit Equilibrium ◽  
Particle Swarm ◽  
Limit Equilibrium Method ◽  
Swarm Optimization ◽  
Equilibrium Method

This paper proposes a modified particle swarm optimization algorithm coupled with the finite element limit equilibrium method (FELEM) for the minimum factor of safety and the location of associated noncircular critical failure surfaces for various geotechnical practices. During the search process, the stress compatibility constraints coupled with the geometrical and kinematical compatibility constraints are firstly established based on the features of slope geometry and stress distribution to guarantee realistic slip surfaces from being unreasonable. Furthermore, in the FELEM, based on rigorous theoretical analyses and derivation, it is noted that the physical meaning of the factor of safety can be formulated on the basis of strength reserving theory rather than the overloading theory. Consequently, compared with the limit equilibrium method (LEM) and the shear strength reduction method (SSRM) through several numerical examples, the FELEM in conjunction with the improved search strategy is proved to be an effective and efficient approach to routine analysis and design in geotechnical practices with a high level of confidence.

Analysis of the Stability of Thawing Slopes by Random Finite Element Method

2019 ◽  
Vol 2673 (10) ◽  
pp. 465-476 ◽  
Author(s):  
Shaoyang Dong ◽  
Xiong (Bill) Yu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Factor Of Safety ◽  
Limit Equilibrium ◽  
Element Model ◽  
Frozen Soil ◽  
Silty Clay ◽  
Local Factor ◽  
The Stability ◽  
Random Finite Element

A significant number of landslides occur in cold regions because of freezing and thawing cycles. The instability of thawing slopes can cause serious damage to transportation infrastructure and property, and even loss of human life. This type of landslide is difficult to analyze by the traditional limit-equilibrium methods, however, because of the complicated multi-physics processes involved. This paper describes a holistic microstructure-based random finite element model (RFEM) to simulate the stability of a thawing slope. The RFEM model is developed to simulate the bulk behaviors of frozen and unfrozen soils based on the behaviors of individual phases. The phase coded image of a frozen silty clay is first custom built and then converted into a finite element model. The mechanical behaviors of individual phases of the frozen soil are calibrated by uniaxial compressive test. The triaxial test is then simulated by RFEM to obtain the shear strength parameters of frozen and unfrozen soils. Coupled thermal-mechanical REFM models are developed to simulate the effects of temperature on the displacement field and stress field in the slope. From the results, the local factor of safety field can be determined. The development of local factor of safety and potential failure surface associated with the thawing process over a typical year are simulated by this new model. The variations in the stability of thawing slopes predicted by this model are consistent with field observations as well as the global-wise slope stability analysis.

An approximate method for estimating the stability of geotextile-reinforced embankments

1985 ◽  
Vol 22 (3) ◽  
pp. 392-398 ◽  
Author(s):  
R. K. Rowe ◽  
K. L. Soderman
Keyword(s):  
Finite Element ◽  
Shear Strength ◽  
Limit Equilibrium ◽  
Soft Clay ◽  
Soil Reinforcement ◽  
Short Term ◽  
Critical Height ◽  
Reinforced Embankments ◽  
The Stability ◽  
Conventional Limit

A method of estimating the short-term stability of reinforced embankments constructed on a deposit that can be idealized as being uniform and purely cohesive is described. This approach maintains the simplicity of conventional limit equilibrium techniques while incorporating the effect of soil–geotextile interaction in terms of an allowable compatible strain for the geotextile. This allowable compatible strain may be deduced from a design chart and depends on the foundation stiffness, the embankment geometry, the depth of the deposit, and the critical height of an unreinforced embankment. The procedure is checked against finite element results and against one published case history. Key words: embankment, geotextile, analysis, limit equilibrium, finite element, soft clay, shear strength, soil reinforcement.

Earthquake Impact Analyses on Slopes Using Finite Element and Limit Equilibrium Methods

2010 ◽  
Vol 163-167 ◽  
pp. 3868-3871
Author(s):  
Yu Hwang Ong ◽  
Anuar Kasa ◽  
Zamri Chik ◽  
Taha Mohd Raihan
Keyword(s):  
Finite Element ◽  
Factor Of Safety ◽  
Limit Equilibrium ◽  
Friction Angle ◽  
Determine Factor ◽  
Earthquake Activity ◽  
Limit Equilibrium Methods ◽  
Dynamic Analyses ◽  
Cut Slopes ◽  
Steep Slopes

The objective of this research is to determine factor of safety for various cut slopes under the influence of earthquake activity. Finite element method was used to generate initial static stress condition and run dynamic analyses of the cut slopes. Factor of safety was then calculated using limit equilibrium method. Both sand and clay were analyzed in this study. The results show that steep slopes with initial safety factor of 1.5 are capable to sustain earthquake magnitude of 0.25g due to high shear strength of the soil. However, slopes with friction angle less than 21º for sand and cohesion value less than 38 kPa for clay are not stable. This shows that earthquake loading should be considered in the design of cut slopes in Malaysia.

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.

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