Three-dimensional Slope Stability Analysis Research Articles

Three-dimensional slope stability analysis based on irregular ellipsoid sliding surface

The determination of the critical sliding surface is a crucial aspect of slope stability analysis. In reality, the environment in which slopes are located is often very complex, and the sliding surfaces have different shapes. Therefore, a three-dimensional stability study is proposed, using irregular ellipsoidal shapes as the sliding surface. By constructing the equation of the irregular ellipsoid and applying spatial geometric transformations, an irregular ellipsoid controlled by six parameters, (semi-axis length (a), width (b), height (c), rotation angle (θ), and spatial displacements (tx and tz)), is obtained. The interpolation method is employed to apply the irregular ellipsoid to 3D slopes, thereby generating irregular ellipsoidal sliding surfaces. The slope stability coefficient is calculated by using the residual thrust method and genetic algorithm to determine the critical sliding surface. A comparative stability analysis is conducted between the standard ellipsoidal sliding surface and the irregular ellipsoidal sliding surface through a classic case study. The results show that the Type II irregular ellipsoidal sliding surface aligns well with the mining area. Finally, the research findings are applied to the 3D slope stability analysis of the Shengli West No.2 Open-Pit Coal Mine in China, validating the feasibility of the proposed method.

Back analysis of the shear strength parameters of 3D landslides with Bayesian approach and reliability theory

To establish an accurate model for determining the shear strength parameters of sliding surfaces while considering the variability and uncertainty of geotechnical parameters, a reliability back analysis method for parameters based on Bayesian theory and a three-dimensional slope stability analysis method are proposed in this paper. First, the prior information of shear strength parameters is updated according to the field test information based on Bayesian theory. Then, combined with the reliability theory, the influences of different two-dimensional and three-dimensional sliding surface shapes on the parameters back analysis are studied. The results show that the uncertainty of parameters decreases with the increase in the amount of test data after introducing the test data to update the mastered parameter information based on Bayesian theory, and it is of great significance to consider the shape and three-dimensional effect of the sliding surface accurately to improve the accuracy of parameter determination and slope stability analysis.

Physics-informed optimization for a data-driven approach in landslide susceptibility evaluation

Landslide susceptibility mapping is an integral part of geological hazard analysis. Recently, the emphasis of many studies has been on data-driven models, notably those derived from machine learning, owing to their aptitude for tackling complex non-linear problems. However, the prevailing models often disregard qualitative research, leading to limited interpretability and mistakes in extracting negative samples, i.e. inaccurate non-landslide samples. In this study, Scoops 3D (a three-dimensional slope stability analysis tool) was utilized to conduct a qualitative assessment of slope stability in the Yunyang section of the Three Gorges Reservoir area. The depth of the bedrock was predicted utilizing a Convolutional Neural Network (CNN), incorporating local boreholes and building on the insights from prior research. The Random Forest (RF) algorithm was subsequently used to execute a data-driven landslide susceptibility analysis. The proposed methodology demonstrated a notable increase of 29.25% in the evaluation metric, the area under the receiver operating characteristic curve (ROC-AUC), outperforming the prevailing benchmark model. Furthermore, the landslide susceptibility map generated by the proposed model demonstrated superior interpretability. This result not only validates the effectiveness of amalgamating mathematical and mechanistic insights for such analyses, but it also carries substantial academic and practical implications.

Three-dimensional slope stability analysis method based on perturbation displacement isosurface

Three-dimensional slope stability analysis method based on perturbation displacement isosurface

A new perspective on determination of the critical slip surface of three-dimensional slopes

In the traditional slope stability analysis, the shape and location of critical slip surface (CSS) are identified by an objective function with the minimum safety factor (SF). However, the method cannot identify the true CSS when the minimum SFs of different critical slip surfaces are equal or extremely close. In order to solve the issue, the idea of slip surface with the maximum sliding direction (SD) as the CSS is proposed in this paper. The shape of CSS is regarded as a rotational ellipsoid with 6 parameters, and the genetic algorithm (GA) is adopted to search for the location of CSS. The three-dimensional (3D) slope stability analysis is performed based on the minimum potential energy principle, which provides an analytical formulation of SD as well as SF without iteration. Two benchmark slopes and a practical engineering case are employed to verify the rationality of the proposed method. The parametric analysis reveals that the larger SD the smaller SF. The developed method is a useful technique support for determining the CSS and the shape of 3D slope.

Composition analysis and distributed assumption GIS model of normal stress on the slope sliding surface

For the limit equilibrium method based on the assumption model of sliding surface normal stress, the more reasonable the assumed sliding surface normal stress model is, the higher the accuracy of the calculation results will be, which is of great significance to improve the theoretical calculation accuracy. Combined with the powerful spatial data analysis ability of Geographic Information Systems (GIS), the expression of the normal stress distribution function of the slip surface is deduced by establishing a GIS-based three-dimensional slope stability analysis model and limit equilibrium equations. By analyzing the composition of the normal stress distribution on the sliding surface, the composition of the normal stress on the sliding surface is obtained, and then the assumed model of the normal stress distribution on the sliding surface is constructed. Finally, the assumed GIS model of the sliding surface normal stress distribution is verified by calculating the proportion. The model overcomes the problem that the stability factor of the slope will cause large errors in the three-dimensional state, and provides a theoretical calculation basis for the establishment of a three-dimensional slope limit equilibrium method based on the assumption of normal stress on the slip surface in GIS.

The Instability of High-Steep Road Cutting Slope: A 3D Continuum-Discrete Coupling Method

In this paper, the 3D continuum-discrete coupling analysis method combined with the strength reduction theory is used to study the macrodeformation, stress law, and microfracture mechanism of a high and steep cutting slope of Zhongkai Expressway in Guangdong Province. The 3D continuum-discrete coupling slope model is established based on the finite difference software FLAC and the discrete element program PFC. Then, based on the correlations between stress tensor and force chain, displacement and shear strain increment, plastic deformation, and microfracture, the mechanism of slope instability is analyzed from macro- and microscales. The research shows the following: (1) the continuum-discrete coupling model is reasonable and effective in the three-dimensional slope stability analysis. (2) The coupling domain was penetrated by the shear band, and the upper part displacement of the coupling domain was large, whose direction was basically consistent with the shear band direction; thus, the slope slip surface was formed. (3) The microfracture can represent the macroscopic failure phenomenon, and the slope landslide can be interpreted as the result of shear fracture in slip direction, accompanied by the extension and penetration of tension crack.

Three-dimensional limit equilibrium slope stability analysis on real slope failures caused by heavy rain and earthquake

Three-dimensional limit equilibrium slope stability analysis on real slope failures caused by heavy rain and earthquake

A three-dimensional slope stability analysis method based on finite element method stress analysis

A new three-dimensional slope stability analysis method based on stress calculation by the finite element method is proposed. This method conforms to the uniform assumption of the sliding direction of the rigid limit equilibrium method and can easily be used calculate the three-dimensional sliding direction. By using this method, both the local and global safety factors of the slip surface can be calculated according to the integral mean value theorem. Additionally, an improved ellipsoidal slip surface construction method is proposed for roughly searching for the minimum safety factor and the critical slip surface. A two-stage particle swarm optimization is used to search for the critical slip surface more accurately. Two numerical examples of fixed slip surfaces are provided to confirm the effectiveness of the proposed method and its applicability to nonspherical slip surfaces. The influence of the slip surface mesh grid size, boundary conditions, Poisson's ratio, and dilatancy angle on the calculation results is revealed. Another two numerical examples of searching for the critical slip surface are then provided, and the results of the proposed method are compared with the results of the strength reduction method to confirm the validity of the proposed method.

Role of unsaturated soil properties in the development of slope susceptibility map

A slope susceptibility map which incorporates unsaturated soil mechanics is essential to the accurate location of areas susceptible to rainfall-induced slope failures. The aim of this study was to develop slope susceptibility maps for zonations within Jurong Formation residual soils in Singapore with the incorporation of unsaturated soil parameters. Slope susceptibility maps were developed through one-dimensional seepage analyses using a transient rainfall infiltration and grid-based regional slope-stability model (TRIGRS) and three-dimensional slope stability analyses using Scoops3D. Laboratory testing of soil properties and two-dimensional (2D) seepage and slope stability analyses were conducted to evaluate the results from the slope susceptibility map. Comparison between the slope susceptibility map and the results from 2D analyses showed that the factors of safety from the slope susceptibility map were consistently lower than those of 2D analyses. Therefore, the proposed method incorporating unsaturated soil in the development of a slope susceptibility map was concluded to be reasonable, on the conservative side.

Three-dimensional slope stability analysis incorporating unsaturated soil properties in Singapore

ABSTRACT Rainfall-induced slope failure is a natural hazard that occurs in many parts of the world. To identify areas where rainfall-induced slope failure may potentially occur in Singapore, a slope susceptibility map of needs to be developed. Majority of the slope failures occurred in residual soils during or after torrential rainfall. In Singapore, residual soils are generally unsaturated because of the deep groundwater table. Hence, it is important to incorporate unsaturated soil properties (i.e. soil–water characteristic curve) in the development of slope susceptibility map in Singapore. In this study, spatial distributions of saturated and unsaturated soil properties were estimated using ordinary kriging. Seepage analysis of zonation in the residual soil from Bukit Timah Granite was carried out using Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability Model (TRIGRS), a publicly available software. The resulting pore-water pressures from the seepage analyses were incorporated into Scoops3D for three-dimensional slope stability analyses. Most areas in the investigated zone were found to have high factors of safety. Only 0.054% of the investigated zonation was associated with very low factors of safety.

A reformulated hardening soil model

The hardening soil (HS) model is an advanced soil plasticity model, which incorporates many features including stiffness stress dependency, hardening from initial loading and soil dilatancy. In this paper, the HS model is explored in depth and two improvements are proposed. The first is a new shear yield surface and hardening rule that have been reformulated to remove singularities. The second is a robust implicit return mapping scheme. Options for improving the global convergence of finite-element analyses are also explored. Single-elements tests replicate results from experimental triaxial data and previous versions of the HS model very closely, and at excellent convergence rates. In addition, a slope stability analysis is performed using the φ − c strength reduction method in two-dimensional plane strain. The results from the slope analysis showed good agreement with analytical and graphical slope stability methods. A three-dimensional (3D) slope stability analysis was also conducted with modified boundary conditions, in order to demonstrate the 3D capabilities of the model.

Stability Analysis of Unsupported Vertical Cuts in the Vadose Zone using 2D and 3D Numerical Methods

Evidence supporting the implementation of three-dimensional (3D) slope stability analysis in geotechnical engineering practice has been mounting since the nineteen-seventies. Current levels of computational power and its accessibility has allowed researchers to investigate the significance of the 3D numerical analysis output compared to conventional 2D limit equilibrium approach. This study compares results of stability analyses of unsupported vertical cuts in the vadose zone using both 2D (GeoStudio 2019 R2) and 3D (FLAC3D) software. Numerical analyses are carried out for various dimensions of unsupported vertical cuts excavated in an unsaturated glacial till. The findings from two different methods (i.e. 2D and 3D) and the limitations of 2D stability analysis are discussed.

The influence of number of grid points and radius increments in determining safety factor and estimated sliding volume on three-dimensional slope stability analysis

The existence of geometric complexity in the longitudinal direction makes 3D Limit Equilibrium Method (LEM) able to depict conditions in the field well and obtain Safety Factor (SF) that is more representative than the 2D limit equilibrium method. Safety factor calculations are not only influenced by the Direction of Sliding (DoS), but also by the location of the slip surface. Therefore, determining the location of the slip surface is important in the 3D limit equilibrium method. In this study, the method used for generating slip surfaces is a grid search where variations are made on the number of grid points and the radius increments to determine the effect of these two variables on the determination of safety factor and estimated sliding volume. Based on the results of the study, it can be stated that the greater the number of grid points and the radius increments, the estimated sliding volume will be more precise, while the calculation of safety factor is only affected by the number of grid points where the greater the number of grid points, the search of critical slip surface will be more accurate.

Three-Dimensional Slope Stability Analysis Incorporating Coupled Effects of Pile Reinforcement and Reservoir Drawdown

AbstractIn pile-reinforced dams and bank slopes, the antislide effect of piles and drawdown of reservoirs are two aspects that could significantly affect the slope stability. However, existing stud...

Three-dimensional (3D) slope stability analysis using stability charts

Stability of slopes is a very serious issue in the field of geotechnical engineering. The analysis and design of failing slopes requires a thorough knowledge of the failure mechanism in order to choose the right slope stability analysis method. The two-dimensional (2D) slope stability methods are very common to the engineers because of the simplicity in their assumptions. As a result the analysis results vary greatly between the different analysis methods. The importance of three-dimensional (3D) slope stability analysis greatly increased where the geometry of the problem becomes complex which makes it very difficult to solve using 2D analysis. A lot many 2D slope stability methods were extended to 3D methods since 1970s based on limit equilibrium (LE) and finite element approaches. In this paper, slopes were analysed using 3D limit equilibrium method (LEM) using SLIDE3 software having different geometry and soil parameters and finally stability charts were prepared to calculate the FOS of the slopes. It is found that the slope stability factor can be read from the stability charts without the need for iterations.

Three-Dimensional Slope Stability Analysis of Convex Turning Corners

AbstractSlopes forming convex corners are often constructed in practice. Observed failures of such corners possess three-dimensional (3D) characteristics. Hence, assessing corner stability requires...

Combined methodology for three-dimensional slope stability analysis coupled with time effect: a case study in Germany

High-steep slopes in open pit mines are much more likely to collapse due to mining operations. Challenges such as data acquisition, precise numerical models and adaptable methodologies have impeded more reliable results of slope stability analysis based on the current methods. Within this context, this paper proposes a combined methodology using light detection and ranging technology to capture high-resolution slope geometry, three-dimensional geological and geotechnical modeling technologies for creating high-quality numerical simulation models and finite-element slope stability analyses combined with a new automatic strength reduction technique to analyze complex geotechnical problems. At the end, the methodology introduces a time series analysis to improve the reliability of the calculated factor of safety. A case study in the deepest open pit mine in Hambach, Germany, was conducted to test and demonstrate the effectiveness and applicability of the proposed methodology.

3D effects of turning corner on stability of geosynthetic-reinforced soil structures

Current design procedures of Geosynthetic-Reinforced Soil Structures (GRSS's) are for walls/slopes with long straight alignments. When two GRSS segments intersect, an abrupt change in the alignment forms a turning corner. Experience indicate potential instability problems occurring at corners. The purpose of this study is to explore the effects of turning corner on the stability of reinforced slopes. Three-dimensional (3D) slope stability analysis, based on limit equilibrium, resulted in the maximum tensile force of reinforcement. Parametric studies required numerous computations considering various geometrical parameters and material properties. The computed results produced efficient practical format of stability charts. For long-term stability of reinforced slopes with turning corner, the influences of pore water pressure and seismic loading are also considered. Turning corner can improve the stability of reinforced slopes by virtue of inclusion of end effects. However, localized increase of pore water pressure or directional seismic amplification may decrease locally thus stability requiring strength of reinforcement larger than in two-dimensional (2D) plane-strain. While using 2D analysis for non-localized conditions may require stronger reinforcement, it also requires shorter reinforcement than in 3D analysis; i.e., 2D analysis may be unconservative in terms of reinforcement length.

Three-dimensional slope stability analysis of block sliding slope failure at the Pikeview Quarry, El Paso County, Colorado

Three-dimensional slope stability analysis of block sliding slope failure at the Pikeview Quarry, El Paso County, Colorado