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.

Non-Linear Hoek-Brown Shear Strength Reduction Technique Considering the Effect of Dilation

2012 ◽  
Vol 446-449 ◽  
pp. 1524-1530
Author(s):  
Ting Ai ◽  
Ru Zhang ◽  
Li Ren ◽  
Wen Xi Fu
Keyword(s):  
Shear Strength ◽  
Factor Of Safety ◽  
Limit Equilibrium ◽  
Limit Equilibrium Method ◽  
Strength Reduction ◽  
Equilibrium Method ◽  
Non Linear ◽  
Stability Of Slope ◽  
The Stability ◽  
Shear Strength Reduction

In order to implement the non-linear Hoek-Brown (HB) shear strength reduction (SSR) on commercially available softwares, this paper derives the relationship between the Drucker-prager (DP) criterion and HB criterion under the condition of plane strain. The equivalent DP parameters can be approximately estimated after serious transformations of parameters between the HB and Mohr-Coulomb (MC) yield functions. To assess the effect of dilation on the stability of slope, the non-associated flow rule, which cannot be contained in the existing limit equilibrium methods, is selected in our analysis, and the SSR-based results of a simple slope indicate that: If the angle of dilatancy ψ is taken to be zero, the factor of safety calculated by the SSR method is very close to that by the limit equilibrium method; if ψ is greater than zero, the factor of safety calculated by the SSR method is greater than that by the limit equilibrium method, and the effect of dilation on the stability of slope can be approximately described by a liner function.

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.

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.

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.

General limit equilibrium method for lateral earth force

1984 ◽  
Vol 21 (1) ◽  
pp. 166-175 ◽  
Author(s):  
Harianto Rahardjo ◽  
Delwyn G. Fredlund
Keyword(s):  
Shear Strength ◽  
Slip Surface ◽  
Pore Water Pressure ◽  
Limit Equilibrium ◽  
Water Pressure ◽  
Vertical Wall ◽  
Limit Equilibrium Method ◽  
External Loading ◽  
Equilibrium Method ◽  
General Limit

The calculation of the lateral earth force using the limit equilibrium method of slices is an indeterminate problem. An assumption regarding the direction or the magnitude of certain forces, or the position of the line of thrust can be used to render the problem determinate.A general formulation for the lateral earth force is derived in accordance with the assumptions involved in the general limit equilibrium (GLE) method. An assumption concerning a direction of the interslice forces is utilized to solve the problem of indeterminancy. Horizontal force equilibrium conditions within a sliding mass are used to compute the magnitude of the active and passive forces. The point of application of the lateral earth force is obtained by considering moment equilibrium for each slice.The coefficient of lateral earth force obtained from the GLE method agrees closely with the results obtained from most other theories. Comparisons are made to the Coulomb theory (i.e., using a planar slip surface) and other theories using a curved or a composite slip surface.Data are presented for the case of a horizontal cohesionless backfill against a vertical wall. The lateral earth force can be contoured on the grid of centers of rotation. These contours have a bell-shaped characteristic and can be used to locate the critical center of rotation.The main advantage of this method lies in its capability to analyze arbitrarily stratified soil deposits with complex geometries. Different conditions of pore-water pressure, shear strength, and external loading can be accommodated in the analysis. Factors of safety greater than 1.0 can be applied to the shear strength of the soil for design purposes. Keywords: lateral earth force, active force, passive force, general limit equilibrium, interslice forces, and coefficient of lateral earth force.

Slope Stability Analysis under the Condition of Seepage

2012 ◽  
Vol 204-208 ◽  
pp. 241-245
Author(s):  
Yang Jin
Keyword(s):  
Finite Element Method ◽  
Shear Strength ◽  
Slope Stability ◽  
Negative Impact ◽  
Strength Reduction ◽  
Soil Slope ◽  
Failure State ◽  
Calculation Results ◽  
The Stability ◽  
Shear Strength Reduction

The stability of soil slope under seepage is calculated and analyzed by using finite element method based on the technique of shear strength reduction. When the condition of seepage or not is considered respectively, the critical failure state of slopes and corresponding safety coefficients can be determined by the numerical analysis and calculation. Besides, through analyzing and comparing the calculation results, it shows that seepage has a negative impact on slope stability.

Analysis of Unstable Rock-Mass Stability Based on Limit Equilibrium Method and Strength Reduction Method

2016 ◽  
Vol 858 ◽  
pp. 73-80
Author(s):  
Ying Kong ◽  
Hua Peng Shi ◽  
Hong Ming Yu
Keyword(s):  
Rock Mass ◽  
Failure Mode ◽  
Posterior Margin ◽  
Reduction Method ◽  
Limit Equilibrium ◽  
Limit Equilibrium Method ◽  
Strength Reduction ◽  
Strength Reduction Method ◽  
Rock Masses ◽  
Unstable Rock

With the slope unstable rock masses of a stope in Longsi mine, Jiaozuo City, China as the target, we computed and analyzed the stability of unstable rock masses using a limit equilibrium method (LEM) and a discrete element strength reduction method (SRM). Results show that the unstable rock masses are currently stable. Under the external actions of natural weathering, rainfall and earthquake, unstable rock mass 1 was manifested as a shear slip failure mode, and its stability was controlled jointly by bedding-plane and posterior-margin steep inclined joints. In comparison, unstable rock mass 2 was manifested as a tensile-crack toppling failure mode, and its stability was controlled by the perforation of posterior-margin joints. From the results of the 2 methods we find the safety factor determined from SRM is larger, but not significantly, than that from LEM, and SRM can simulate the progressive failure process of unstable rock masses. SRM also provides information about forces and deformation (e.g. stress-strain, and displacement) and more efficiently visualizes the parts at the slope that are susceptible to instability, suggesting SRM can be used as a supplementation of LEM.

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