A Further Study on Soil Slope Stability Analysis by Finite Element Slip Surface Stress Method

2012 ◽  
Vol 204-208 ◽  
pp. 492-501
Author(s):  
Hong Jun Li ◽  
Yan Yi Zhang ◽  
Zu Wen Yan
Keyword(s):  
Shear Strength ◽  
Equilibrium State ◽  
Surface Stress ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Strength Reduction ◽  
Engineering Practice ◽  
Limit Equilibrium State ◽  
Ultimate Limit ◽  
Sliding Force

In this paper, it proves that the necessary and sufficient condition for the potential sliding body reaching the ultimate limit equilibrium state is that the summation of shear stresses along the sliding surface equals to that of resistant shear strength. Based on the rigorous theory analyses and derivations, it is clearly shown that the definition of factor of safety (FOS) in the slip surface stress method (SSSM) is irrelevant with the shape of slip surface. Thus, the authors demonstrate that the FOS of noncircular slip surface can also be defined as the ratio of the sum of resistant sliding force along slip surface to that of sliding force. Furthermore, the physical meaning of the FOS in the SSSM, which can be taken as the average evaluation of the strength reduction coefficient that makes the sliding body reach the ultimate limit equilibrium state along the slip surface in nature, is formulated on the basis of strength reserving theory rather than the overloading theory like that in the Limit Equilibrium Method (LEM) and the Shear Strength Reduction Method (SSRM). Finally, the factors of safety (FOS) and the locations of critical failure surfaces obtained by the SSSM, LEM and SSRM are compared for various geotechnical practices. It is found that the SSSM can achieve precise and reasonable stability assessments for the soil slopes on the basis of actual stress field. Consequently, compared with the LEM and SSRM, the SSSM is demonstrated to be effective and efficient alternative approach for routine analysis and design in geotechnical engineering practice with a high level of confidence.

An Approach for Landslide Stability Evaluation by Numerical Method

2011 ◽  
Vol 462-463 ◽  
pp. 42-47
Author(s):  
Xiao Li Liu ◽  
Jun Jie Yang
Keyword(s):  
Shear Strength ◽  
Plastic Zone ◽  
Numerical Method ◽  
Critical State ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Limit Equilibrium Method ◽  
Strength Reduction ◽  
Landslide Stability ◽  
Shear Strength Reduction

For numerical simulation, the shear strength reduction technique (SSRT) is often used to evaluate slope or landslide stability. According to numerical computation results of slopes or landslides analyzed by SSRT, it can be found that with increase of the shear strength reduction factor, some of the soil elements will yield gradually to form a connected plastic zone, which is the potential slip surface of the slope or landslide. In view of the plastic resistance of soils, formation of the connected plastic zone does not always indicate that the landslide is about to failure. Other auxiliary criterion is necessary to predict whether a slope or landslide is in a critical state or not. Here, difference of the incremental percent of horizontal displacement of the outcropping slip surface node is regarded as the auxiliary indicator to distinguish the critical state of slopes or landslides after formation of the potential slip surface. With the ideas mentioned above, stability of a fossil landslide, Xietan landslide has been analyzed for the natural and the long-term reservoir water level conditions. Factors of safety of Xietan landslide by the numerical method have been compared with that by the limit equilibrium method, which indicates that the method used here for evaluating stability of Xietan landslide is feasible. Because numerical method has more advantages over the limit equilibrium method, the approach for evaluating stability of landslide here can be applied to more complicated or three-dimensional landslides or slopes further.

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.

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

2011 ◽  
Vol 243-249 ◽  
pp. 2271-2275
Author(s):  
Shu Yu ◽  
Li Hong Chen ◽  
Ze Ping Xu ◽  
Ning Chen
Keyword(s):  
Shear Strength ◽  
Slope Stability ◽  
Reduction Method ◽  
Slip Surface ◽  
Strength Reduction ◽  
Strength Parameter ◽  
Strength Reduction Method ◽  
Critical Slip Surface ◽  
Rockfill Dam ◽  
The Earth

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.

Modeling cover-collapse sinkhole based on the theory of shells

2019 ◽  
Vol 08 (01) ◽  
pp. 1850028
Author(s):  
Zhen Liu ◽  
Cuiying Zhou ◽  
Zichun Du ◽  
Dingli Su ◽  
Jieming Li ◽  
...  
Keyword(s):  
Equilibrium State ◽  
Limit Equilibrium ◽  
Critical Factors ◽  
Karst Terrain ◽  
Collapse Sinkhole ◽  
Limit Equilibrium State ◽  
Soil Arch ◽  
Collapse Phase ◽  
Theory Of Shells

The shape and height of a natural balanced soil arch are two of the critical factors for the development of a sinkhole. The exposure of the natural balanced soil arch can be described as the initiation of the surface-collapse phase of the cover-collapse sinkhole in karst terrain. In this paper, by simplifying the natural balanced soil arch as a thin shell in a limit equilibrium state, a theoretical model is developed using the nonmoment theory of rotary shells with the shape and height of the natural balanced soil arch derived based on the Protodyakonov’s theory. First, the developed model is validated using a case study (a cover-collapse sinkhole occurred in Guizhou, China). It demonstrates that the shell theory used in this study can describe the equilibrium state of a natural balanced soil arch reasonably well. After model validation, a series of numerical simulations are then carried out to investigate the critical factors which govern the collapse of a sinkhole. The results show that buried depth serves as a compulsory condition for the formation of the natural balanced soil arch. Furthermore, it shows that a buried depth less than six times of the radius of a cave could result in the formation of a natural balanced soil arch in the cone surface.

Study of Failure Modes of Suction Anchors

2011 ◽  
Author(s):  
Qiyi Zhang ◽  
Sheng Dong
Keyword(s):  
Finite Element ◽  
Bearing Capacity ◽  
Failure Mode ◽  
Failure Modes ◽  
Limit Equilibrium ◽  
Element Model ◽  
Ultimate Bearing Capacity ◽  
Engineering Practice ◽  
Element Analysis ◽  
Limit Equilibrium State

Suction foundations are widely used in deep sea and their ultimate bearing capacity which is closely related with failure modes of suction anchor at limit equilibrium state is a key technology in offshore engineering practice. Based on Coulomb friction theory, an exact finite element model is presented in this paper. On the basis of this FEM model, by use of the finite element analysis software ABAQUS, the effect of mooring point and aspect ratio of a suction anchor on the ultimate bearing capacity and its stability are researched in detail. The results show that the ultimate bearing capacity and stability of the suction anchor are affected vastly by the position of mooring point, and the variation of mooring point on the suction anchor can lead to different failure modes. Simultaneously, the results also shows that tilted rotation of the soil along the direction of the mooring force will occur when the mooring point is near the top of the suction anchor, and the soil near the bottom of the fixed anchor rotates around the center of a circle, so the failure mode is called forward-tilted rotation in this paper; A general translation slip of the soil in front of the anchor along the direction of the mooring force will occur when mooring point is below midpoint of suction anchor, so the failure mode is called the translation slip failure mode in this paper. Anticlockwise tilted rotation of the soil along the direction of mooting force will occur when the mooring point is near the bottom of the anchor, and the soil at the top of the anchor rotates around the center of a circle, so the failure mode is called backward-tilted rotation in this paper.

Searching Sliding Surface of Homogeneous Soil Slope by Maxing Residual Sliding Force

2013 ◽  
Vol 353-356 ◽  
pp. 55-59
Author(s):  
Ming Wei Zou ◽  
Wei Jiang ◽  
Zhi Qi Lu
Keyword(s):  
Limit Equilibrium ◽  
Engineering Problem ◽  
New Method ◽  
Engineering Practice ◽  
Sliding Surface ◽  
Soil Slope ◽  
Equilibrium Equations ◽  
Homogeneous Soil ◽  
The Stability ◽  
Sliding Force

The stability of soil slope is a common engineering problem and many scholars and experts have done abundant works on it since 1940s. By utilizing limit equilibrium equations, some slice methods had been proposed to search the most dangerous sliding surface, and they obtain enormous success. This article focuses on the fact that residual sliding force is an important parameter to design resistant structures in Chinese engineering practice. While the most dangerous sliding surface does not coincide with the sliding surface which the largest residual sliding forces locates on. So we compile the program to find the sliding surface by maxing residual sliding force. And some sample examples are executed, the surfaces comes from new method are compared with surfaces form Janbu Method. Some interesting conclusions are obtained.

Study on Embedded Pile Length in Slope Reinforced

2011 ◽  
Vol 105-107 ◽  
pp. 1497-1504 ◽  
Author(s):  
Qiu Sheng Liu ◽  
Dong Feng Liu
Keyword(s):  
Shear Strength ◽  
Theoretical Analysis ◽  
Slip Surface ◽  
Three Dimensional ◽  
Strength Reduction ◽  
Plastic Shear ◽  
Pile Head ◽  
Pile Spacing ◽  
Pile Length ◽  
Shear Strength Reduction

The embedded length of anti-slide piles reinforcing slopes is analyzed by three-dimensional elasto-plastic shear strength reduction finite difference method. The effect of embedded pile length on safety factor and pile behavior, and the effects of the pile spacing, pile head conditions, bending stiffness and soil style on pile length and pile behavior are analyzed. The results show that the pile spacing and the pile head conditions have significant influence on the critical pile length. The critical pile length is seen to increase with decreasing pile spacing, and smaller pile spacing tends to increase the integrity of the piled slopes. A theoretical analysis of the slip surface is also described, and the slip surface determined by the pressure on piles considering the influences of both soil and the piles of slopes is in agreement with previous researches.

scholarly journals The 22 February 2018 landslide mechanism in Pasir Panjang Village, Brebes Regency, Central Java, Indonesia

2019 ◽  
Vol 4 (2) ◽  
pp. 92
Author(s):  
Wahyu Wilopo ◽  
Adam Raka Ekasara ◽  
Hendy Setiawan ◽  
Dwikorita Karnawati
Keyword(s):  
Shear Strength ◽  
Slip Surface ◽  
Pore Water Pressure ◽  
Limit Equilibrium ◽  
Water Pressure ◽  
Back Analysis ◽  
Silty Sand ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Central Java

On 22 February 2018 landslide occurred in Pasir Panjang Village, Salem District, Brebes Regency of Central Java Province, Indonesia. About 8 people were died, 4 people were injured and several infrastructures were damaged due to this landslide. This research is carried out to understand geological-geotechnical condition and to study the initiation mechanism of the landslide. Field investigation and UAV mapping are carried out to detect slip surface and define slope geometry. The rainfall-induced pore-water pressure is estimated by using the Slope Infiltration Distributed Equilibrium (SLIDE) model. Then, limit equilibrium method is used to estimate the safety factor of the slope, while the shear strength parameters are determined by applying back analysis approach that compared with data from laboratory tests. The results show that landslide occurred in permeable layer of silty sand overlaid above impermeable andesitic breccia. Results from back analysis indicate that the shear strength parameters and rainfall intensity are strongly influence the stability of slope against landslide.

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