scholarly journals Three-Dimensional Stability Analysis of a Homogeneous Slope Reinforced with Micropiles

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Shu-Wei Sun ◽  
Wei Wang ◽  
Fu Zhao
Keyword(s):  
Slip Surface ◽  
Three Dimensional ◽  
Failure Surface ◽  
Embedment Depth ◽  
Critical Slip Surface ◽  
Soil Behavior ◽  
Nonlinear Method ◽  
Strength Reduction Technique ◽  
The Stability ◽  
Coulomb Criterion

Micropiles are widely used to reinforce slopes due to their successful performance and fast construction. In this study, a simple nonlinear method is proposed to analyze the stability of a homogeneous slope reinforced with micropiles. This method is based on shear strength reduction technique, in which the soil behavior is described using the nonassociated Mohr-Coulomb criterion and micropiles are modeled as 3D pile elements. A series of slope stability analyses is performed to investigate the coupled mechanism of micropile system, and the optimum of pile position, depth of embedment, and length of truncation are analyzed. Results show that the position of micropile system plays an important role not only in the calculation of the safety factor, but also in locating the failure surface, which demonstrates the dominating coupled effect exists between micropiles and slope. The critical embedment depth of the micropile is about 2 times the length of micropile above the critical slip surface, and the micropiles flexure rather than rotation becomes increasingly prevalent as the depth of micropiles embedment increases. Truncation of micropiles may improve the capacity of the micropile system, and the largest truncation length of micropile is about 1/4 depth of critical slip surface in this study.

scholarly journals Determining the Critical Slip Surface of Three-Dimensional Soil Slopes from the Stress Fields Solved Using the Finite Element Method

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Yu-chuan Yang ◽  
Hui-ge Xing ◽  
Xing-guo Yang ◽  
Jia-wen Zhou
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stability Analysis ◽  
Safety Factor ◽  
Slip Surface ◽  
Three Dimensional ◽  
Soil Slope ◽  
Critical Slip Surface ◽  
The Finite Element Method ◽  
The Stability

The slope stability problem is an important issue for the safety of human beings and structures. The stability analysis of the three-dimensional (3D) slope is essential to prevent landslides, but the most important and difficult problem is how to determine the 3D critical slip surface with the minimum factor of safety in earth slopes. Basing on the slope stress field with the finite element method, a stability analysis method is proposed to determine the critical slip surface and the corresponding safety factor of 3D soil slopes. Spherical and ellipsoidal slip surfaces are considered through the analysis. The moment equilibrium is used to compute the safety factor combined with the Mohr-Coulomb criteria and the limit equilibrium principle. Some assumptions are introduced to reduce the search range of center points and the radius of spheres or ellipsoids. The proposed method is validated by a classical 3D benchmark soil slope. Simulated results indicate that the safety factor of the benchmark slope is 2.14 using the spherical slip surface and 2.19 using the ellipsoidal slip surface, which is close to the results of previous methods. The simulated results indicate that the proposed method can be used for the stability analysis of a 3D soil slope.

scholarly journals Comparative study of material point method and upper bound limit analysis in slope stability analysis

2020 ◽  
Vol 2 (1) ◽  
pp. 44-57
Author(s):  
Lianheng Zhao ◽  
Nan Qiao ◽  
Zhigang Zhao ◽  
Shi Zuo ◽  
Xiang Wang
Keyword(s):  
Stability Analysis ◽  
Upper Bound ◽  
Limit Analysis ◽  
Slope Failure ◽  
Slip Surface ◽  
Material Point Method ◽  
Material Point ◽  
Critical Slip Surface ◽  
The Stability ◽  
Upper Bound Limit Analysis

Abstract The upper bound limit analysis (UBLA) is one of the key research directions in geotechnical engineering and is widely used in engineering practice. UBLA assumes that the slip surface with the minimum factor of safety (FSmin) is the critical slip surface, and then applies it to slope stability analysis. However, the hypothesis of UBLA has not been systematically verified, which may be due to the fact that the traditional numerical method is difficult to simulate the large deformation. In this study, in order to systematically verify the assumption of UBLA, material point method (MPM), which is suitable to simulate the large deformation of continuous media, is used to simulate the whole process of the slope failure, including the large-scale transportation and deposition of soil mass after slope failure. And a series of comparative studies are conducted on the stability of cohesive slopes using UBLA and MPM. The proposed study indicated that the slope angle, internal friction angle and cohesion have a remarkable effect on the slip surface of the cohesive slope. Also, for stable slopes, the calculation results of the two are relatively close. However, for unstable slopes, the slider volume determined by the UBLA is much smaller than the slider volume determined by the MPM. In other words, for unstable slopes, the critical slip surface of UBLA is very different from the slip surface when the slope failure occurs, and when the UBLA is applied to the stability analysis of unstable slope, it will lead to extremely unfavorable results.

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.

Three-dimensional stability analysis for slurry-filled trench wall in cohesionless soil

1996 ◽  
Vol 33 (5) ◽  
pp. 798-808 ◽  
Author(s):  
Jiin-Song Tsai ◽  
Jia-Chyi Chang
Keyword(s):  
Stability Analysis ◽  
Stability Problem ◽  
Slip Surface ◽  
Three Dimensional ◽  
Vertical Direction ◽  
Soil Mass ◽  
Cohesionless Soil ◽  
Cohesionless Soils ◽  
Slurry Trench ◽  
The Stability

On the basis of the limiting equilibrium and arching theory, a three-dimensional analysis is proposed for slurry-supported trenches in cohesionless soils. This analytical approach is developed by considering the trench stability problem as a vertical soil cut within a fictitious half-silo with a rough wall surronding. Arching effects are considered not only in the vertical direction but also in the horizontal direction. A shell-shaped slip surface of the sliding soil mass is defined by Mohr-Coulomb criterion. The factor of safety is defines as the ratio of the resisting force induced by slurry pressure to the horizontal force required to maintain the stability of the trench wall. Results of the proposed method have been compared with those of two existing analytical methods for a typical trench stability problem. Key words: stability analysis, slurry trench wall, cohesionless soil.

Influence of Anisotropic Internal Friction Angle on the Stability of Uniform Soil Slopes

2012 ◽  
Vol 170-173 ◽  
pp. 270-273 ◽  
Author(s):  
Lian Wei Zhang
Keyword(s):  
Slip Surface ◽  
Friction Angle ◽  
Soil Slope ◽  
Critical Slip Surface ◽  
Obvious Effect ◽  
Anisotropic Friction ◽  
Change Of Direction ◽  
Soil Slopes ◽  
Anisotropic Soil ◽  
The Stability

The effect of anisotropy of friction angle in natural deposited soil on the stability of soil slopes was studied in this paper. Stability analysis was performed on a uniform soil slope with anisotropic friction angle. Spencer’s method was used, and the variation of friction angle was assumed to be linear to the change of direction of the slip surface. It was shown that 7-10 percent of change in safety factor might achieve within a 10m-highed anisotropic soil slope. It was also found from the analysis that that frictional anisotropy had no obvious effect on the location of critical slip surface.

Three-dimensional strength-reduction finite element analysis of slopes: geometric effects

2012 ◽  
Vol 49 (5) ◽  
pp. 574-588 ◽  
Author(s):  
T.-K. Nian ◽  
R.-Q. Huang ◽  
S.-S. Wan ◽  
G.-Q. Chen
Keyword(s):  
Finite Element ◽  
Slope Stability ◽  
Slip Surface ◽  
Boundary Effect ◽  
Three Dimensional ◽  
Strength Reduction ◽  
Infinite Length ◽  
Surface Geometry ◽  
Element Analysis ◽  
The Stability

The vast majority of slopes, both natural and constructed, exhibit a complex geometric configuration and three-dimensional (3D) state, whereas slopes satisfying the assumption of plane strain (infinite length) are seldom encountered. Existing research mainly emphasizes the 3D dimensions and boundary effect in slope stability analysis; however, the effect of complex geometric ground configuration on 3D slope stability is rarely reported. In this paper, an elastoplastic finite-element method using strength-reduction techniques is used to analyze the stability of special 3D geometric slopes. A typical 3D slope underlain by a weak layer with groundwater is described to validate the numerical modeling, safety factor values, and critical slip surface for the 3D slope. Furthermore, a series of special 3D slopes with various geometric configurations are analyzed numerically, and the effects of turning corners, slope gradient, turning arcs, and convex- and concave-shaped surface geometry on the stability and failure characteristics of slopes under various boundary conditions are discussed in detail.

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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