Rock Slope Stability Analysis Research Articles

Rock slope stability analysis using photogrammetric data and DFN–DEM modelling

Structural and mechanical analyses of rock mass are key components for rock slope stability assessment. The complementary use of photogrammetric techniques and numerical models coupling discrete fracture networks with the discrete element method (DEM) provides a methodology that can be applied to assess the mechanical behaviour of realistic three-dimensional (3D) configurations for which fracture persistence cannot be assumed. A real case has been studied to show the complete methodology from the acquisition of the photogrammetric data to the numerical modelling of the potential progressive failure process occurring in the rock mass. Using a 3D mapping system and its associated structural mapping tool Sirovision, the topography and the discontinuity set of an unstable rock block located in a limestone layer of the Mount N,ron, located in the French Alps, were imported into a DEM code specially enhanced for the modelling of pre-fractured rock masses. A stability analysis has been carried out, emphasizing the contribution of rock bridge failure through a mixed shear-tensile failure process to the generation of new failure surfaces. This addresses limitations in methodologies using only shear strength reduction method. It is believed that the proposed methodology can strengthen the basis for a more comprehensive stability analysis of complex fractured rock slopes.

Three dimensional seismic and static stability of rock slopes

The kinematical approach of limit analysis is used to estimate the three dimensional stability analysis of rock slopes with nonlinear Hoek-Brown criterion under earthquake forces. The generalized tangential technique is introduced, which makes limit analysis apply to rock slope problem possible. This technique formulates the three dimensional stability problem as a classical nonlinear programming problem. A nonlinear programming algorithm is coded to search for the least upper bound solution. To prove the validity of the present approach, static stability factors are compared with the previous solutions, using a linear failure criterion. Three dimensional seismic and static stability factors are calculated for rock slopes. Numerical results of indicate that the factors increase with the ratio of slope width and height, and are presented for practical use in rock engineering.

Research on Precision of Partial Coefficient Finite Element Method in Stability Analysis for Rock Slope

Partial coefficient finite element method is a new method of analyzing the stability of jointed rock slope. Partial coefficient Finite element analysis of joints rock slope stability, the calculation accuracy will be influenced by many factors, Such as the yield criterion, the mechanical parameters of rock mass, the computing grid, etc. In this paper, combined with example analyzed the impact of these factors on the partial coefficient method calculation accuracy. Considering material partial coefficients of slope’s weak layer, then, the weak layer is reduced by the strength reduction method. Analysis results show that: Using partial coefficient method analysis of stability of rock slope, under the associated flow rule, should choose Mohr-Coulomb inscribed circle criterion. In addition, when using Mohr - Coulomb inscribed circle criterion, the modulus of elasticity and poison’s ratio on the calculation results can be ignored. And with a few elements ideal result can be deduced.

Rock Slope Stability Problems in Wadi Quaz-Dam Site No. 2, Jeddah-Saudi Arabia

The present investigation deals with the engineering geological studies of soil and rock masses in the Wadi Quaz area-Dam No. 2, East of Jeddah. Wadi Quaz area-Dam No. 2, East of Jeddah, Saudi Arabia often faces floods during rainy seasons, so it is so urgent to investigate the area before building any dam or preventing water from flow. Preventing water from flow will produce new dangerous factors such as uplift force which may cause the dam failure. To have a better understanding of the factors that may affect the slope stability, many rock slope locations are observed in detail to assess the effect of discontinuities formed in the rock masses. Fieldwork and Laboratory tests were carried out on soil and rocks. Soils included identification of soil type using unified soil classification system, permeability, water content and field density were done for soils. Rocks include identification of physical and mechanical properties such as: rock type, degree of weathering, rock strength, RQD, joint spacing measurements, and geometric properties (Dip, and Dip direction). Different methods were used to evaluate the potential failure in the studied area depending on rock mass rating and slope stability analysis. The well-known classification of rock masses titled Rock Mass Rating system [1] was used for categorizing the rock masses in the studied area besides slope mass rating [2] which would help to estimate the rock stability. The kinematical analysis was applied to investigate the potential failure mode which might occur in the dam abutments. This paper will provide the stability of dam abutments in both summer season and winter season besides general estimation of the seepage problems related to the soil and according to its permeability.

Stability analysis of rock slope based on an abstraction ant colony clustering algorithm

The study of the stability of rock slope is very important because its instability can cause large disasters. Because the main influence factor of the stability of rock slope is the geological environment, the engineering experience analogy method is a practical and extensively applied method. The main feature of the engineering analogy method is the cluster. Based on the analysis of a dataset of rock slope samples and using the engineering analogy method in relation to the abstraction ant colony clustering algorithm, a new method for rock slope stability analysis is proposed. Using this method, rock slopes can be automatically clustered to obtain the stability status of rock slopes in one class. Therefore, the class rating can represent the stability status of rock slopes. Some real engineering examples are used to verify the computing effect of the new algorithm. Engineering applications prove that this new algorithm can automatically estimate the stability of rock slope with high validity. Its robustness surpasses the robustness of traditional algorithms, and its application is more convenient than that of traditional algorithms. However, as a heuristic algorithm, the selection of algorithm parameters is sometimes challenging, and the computation effect for a highly complex problem is not satisfactory. Therefore, this practical method of slope stability analysis should be popularized.

Numerical simulation on slope stability analysis considering anisotropic properties of layered fractured rocks: a case study

Anisotropy is one of the natural properties of layered fractured rock, and it plays an important role in slope stability analysis, which is a vital problem in the geotechnical engineering. However, in the present engineering design, rock mass is simply treated as isotropic material, which fails to take into account the anisotropic properties. This work begins with formulizations of the anisotropic seepage-stress coupled model for the layered fractured rock slope stability analysis based on the equivalent continuum theory. Next, the model is applied in the numerical simulation of the southern slope of an open-pit mine in China to understand the mechanism of the existing failure strain as well as the failure mechanism of the potential landslide. The computed water table and damage zone have been compared with the field measurements and found to be in good agreement with field observations. Finally, the effective measures to prevent the slope failure and strengthen the slope stability have been suggested. The proposed model successfully applied in the case study indicated that it is much more feasible and efficient comparing with using the traditional isotropic coupled model in such layered fractured rock slopes stability problems.

Multi-scale analysis of water alteration on the rockslope stability framework

Water is an important weathering factor on rock discontinuities and in rock mass mechanical behaviour because of its chemical features such as temperature, pH or salinity which make it a “good” candidate to rock degradation. Furthermore the increase of rainfall frequency or intensity highlights some problems on the rock slope stability analysis. This study aims to evaluate the effect of water flow on the rock slope stability and it is performed at two space scales: in situ scale and laboratory (micro scale and macro scale). It shows how water induces degradation at multi-scale (surface roughness and matrix) and thus may decrease the stability of the discontinuous rock mass. It has two main components: the effect of water-solid chemical mechanisms and the analysis of the mechanical response of the discontinuity modified by the water alteration.

3D Finite Element Numerical Analysis for Stability Calculation of High Steep Rock Slope

Due to the high steep rock slope stability analysis its complex geological conditions and other factors, its stability calculation has been a technical problems the field of slope engineering, in this paper, 3D finite element calculation software Midas GTS for side slope surface topography and slope internal faults, weak structural plane of complex three-dimensional geological modeling, it overcomes the complex slope geological modeling problem and simulates rainfall, earthquakes and other factors affecting the stability on the slope, calculated results more in line with reality, and the software calculates is in accordance with fact, it provides a useful reference for slope engineering.

Unified continuum/discontinuum modeling framework for slope stability assessment

Current dominant methods for slope stability analysis are the limit equilibrium method and the strength reduction method. Both methods are based on the limit equilibrium conditions. However, the limit equilibrium methods are limited to the rigid body assumption, while the strength reduction method is computationally expensive and has convergence issues due to the non-linear iterative computations. In this paper, we propose a current stress-based search algorithm to directly obtain the critical slip surface and the safety factor. The numerical manifold method, which unifies the continuum and discontinuum analysis problems, is used for stress analysis to obtain the stress distribution of soil slopes or rock slopes cut by joints. Based on the stress results obtained, a graph theory is used to convert the solution of the critical slip surface to a shortest path problem, which can be directly solved by the Bellman–Ford algorithm. The proposed method couples the numerical manifold method and the graph theory allowing for stability analyses of both rock and soil slopes within the same framework. The method completely removes the computational effort needed for iterations in the strength reduction method as well as eliminating the rigid body assumptions in the limit equilibrium method.

Research of Cutting Slop Process by Strength Reduction FDM

To the problem of slope stability analysis and slope-cutting of rock slope, the traditional method Limit Equilibrium Method has many shortcomings as assuming the position and shape of the slip plane first. However, with the new theory of Strength Reduction Method, the problem can be easily solved. By selecting the appropriate criterion of instability and failure of sliding surface of slope, the Strength Reduction Method simulates the gradual development process of slope-cutting. By this method, we can simulate the failure process of slope and obtain the safety factors and slipping surface. This paper put forward the process of cutting slop by Strength Reduction FDM (Finite Difference Method) which had new insights into the choice of instability criterion, flow rule and slip plane.

New method for dynamic stability analysis of rock slope under blasting vibration based on equivalent acceleration and Sarma method

Dynamic stability of rock slopes under dynamic blasting disturbance and its analytic method are key problems in slope engineering. Based on wave theory, the relationship between blasting vibration velocity, acceleration, and stress state of slopes is studied. The results indicate that with the same blasting vibration velocity, peak stress of the slopes is identical. An equivalent acceleration calculation method is proposed for the limit equilibrium analysis of rock slope stability under blasting vibration. Considering the dynamic time-varying characteristics of the blasting vibration loading, a time-history method based on the equivalent acceleration and the Sarma method of limit equilibrium analysis is then presented for the dynamic stability analysis of rock slopes. On the basis of this new method, the high rock slopes on the left bank in the Jinping I Hydropower Station are analyzed. Results of the case study derived from the new analytic method indicate that this new method is reasonable.

Modelling the Shear Behaviour of Rock Joints with Asperity Damage Under Constant Normal Stiffness

The shear behaviour of a rough rock joint depends largely on the surface properties of the joint, as well as the boundary conditions applied across the joint interface. This paper proposes a new analytical model to describe the complete shear behaviour of rough joints under constant normal stiffness (CNS) boundary conditions by incorporating the effect of damage to asperities. In particular, the effects of initial normal stress levels and joint surface roughness on the shear behaviour of joints under CNS conditions were studied, and the analytical model was validated through experimental results. Finally, the practical application of the model to a jointed rock slope stability analysis is presented.

Slope stability assessment using both empirical and numerical methods: a case study

Estimating the mechanical properties of a rock mass is an inherently complex task involving numerous uncertainties, especially when performing rock slope stability analysis. Conventional rock mass classification systems with essential adjustments to account for rock discontinuities are a feasible approach to analyzing rock slope stability. Moreover, back analysis of a failed or failing slope can be used as a reliable method of determining the shear strength parameters of rock joints. In this work, the slope stability of Karoun trench was analyzed and its geomechanical parameters were estimated, focusing on the slope mass rating (SMR) and utilizing the back-analysis method. SMR was employed to evaluate the stability of the trench. Numerical simulations were then carried out using the Universal Distinct Element Code software package in order to perform back analysis, thus allowing the mechanical properties of the rock slope to be predicted. Although simpler methods of determining slope instability may be available, the authors wished to focus purely on the capabilities of the SMR and the back-analysis method. The results indicate that the modified SMR is a reliable method for the primary assessment of rock slope stability and for identifying the critical failure mode. Moreover, sliding on bedding planes is the dominant failure mode, and the properties of the discontinuities play a key role in the instability of the considered rock slope.

Numerical Analysis of Stratified Rock Slope Stability Based on 3DEC

Discrete element software is used to simulate the excavation of a rock slope in Puli-Xuanwei Expressway in Yunnan Province. Through monitoring displacement development characteristics in different positions of slope, the result shows that the minimum horizontal displacement under excavation exists in the top of the slope, meanwhile the maximum horizontal displacement occurs in the foot and waist of the slope, and the maximum vertical displacement occurs in the top of the slope. Comparing rock slope in such conditions as different stratum angles, directions, rock characteristics and thickness, it concludes possible failure modes of slope and the variation law of safety coefficient under different conditions. This paper is instructive and offers reference for the practical engineering.

Chart-based slope stability assessment using the Generalized Hoek–Brown criterion

We present new stability charts for the analysis of rock mass slopes satisfying the Generalized Hoek–Brown (GHB) criterion. Firstly, charts for calculating the factor of safety (FOS) of a slope for a specified slope angle β=45° are proposed. Secondly, a disturbance weighting factor fD is introduced to illustrate the effect of disturbance factor D upon the stability of rock slopes. Thirdly, a slope angle weighting factor fβ is proposed to show the influence of slope angle β on slope stability. Combined with stability charts based on β=45°, the weighting factors fD and fβ allow the calculation of the FOS of a slope assigned various slope angle under different blasting damage and stress relief conditions. The reliability of the proposed charts is tested against numerical solutions. The results show that FOS from the proposed charts exhibits only 3.1% average discrepancy from numerical solutions using 1680 sets of data. The proposed charts are simple and straightforward to use and can be adopted as useful tools for the preliminary rock slope stability analysis.

Development of three-dimensional numerical manifold method for jointed rock slope stability analysis

This paper presents a three-dimensional numerical manifold method (NMM) for jointed rock slope stability analysis. The main barriers for realistic rock slope stability analysis are discussed, and the unique features of the NMM which make it stand out in slope analysis are emphasized. The framework of the 3-D NMM is established via a regularly-patterned tetrahedral mesh-based mathematical cover system. A contact detection algorithm is then customized to fit the 3-D NMM characteristics. The developed code is first calibrated by two simple cases: inclined plane sliding and tetrahedral wedge sliding, and then applied to a more complex slope scenario. The complete failure process involving large displacement and rotation of multiple interaction blocks is exhibited dynamically. Two typical stabilization/protection techniques are also investigated. The developed 3-D NMM could be potentially used to find the trigger/failure mechanism of jointed rock slopes, so as to optimize the slope stabilization or protection design.

APPLICATION OF BLOCK THEORY MODELING ON SPATIAL BLOCK TOPOLOGICAL IDENTIFICATION TO ROCK SLOPE STABILITY ANALYSIS

Rock slopes stability has been one of the fundamental issues facing geotechnical engineering researchers. Due to the pre-existing joints, the intactness of the rock is weakened. The mechanical characteristics are changed correspondingly along with joint-induced stress redistribution within the rock mass if the sliding limit at the joint or part of it is exceeded. In this study, spatial block topological identification techniques are applied to distinguish all blocks cut by 3D finite random or fixed discontinuities. Based on the available photographic information of rock slopes, the sliding forces and the corresponding factor of safety are evaluated through limit equilibrium conditions by the classic block theory. The rock slope stability analysis software, GeoSMA-3D (Geotechnical Structure and Model Analysis), satisfying the requirements of spatial block modeling, joint plane simulation, key block identification and analysis and sliding process display, was developed. The application of such a software on the analysis of a rock slope, which is located near the inlet of Daiyuling No. 1 tunnel on the Zhuanghe–Gaizhou highway networks, was performed. The assessed results were compared with the monitored data to validate the effectiveness of such software.

Discontinuous Deformation Analysis Visualization System Based on VTK

Discontinuous Deformation Analysis (DDA) is an emerging numerical simulation technology in rock engineering field, which could be used to analyze discontinuous blocks movement. DDA has been widely used in the areas ranging from rock slope stability analysis, underground chamber constructions to earth quake loading predictions. But so far, there is no pre and post processing program for DDA algorithm. In order to make DDA more effectively meet the needs of practical projects, and analyze the computing results more clearly, effectively and conveniently, in this paper, we use an open source VTK (Visualization Toolkit) system to visualize the results of DDA, design and implement a visualization system. We also developed friendly GUI (Graphic User Interface) based on QT. Finally, we demonstrate this tool with two project examples, which will prove that the visualization system is direct, convenient and easy to extension.

Stability Analysis of Jointed Rock Slope Using Shear Strength Reduction Approach

Finite element method is used to compute the factor of safety of jointed rock slope. The stability of jointed rock slope is simulated by using shear strength reduction approach. Mohr-Coulomb fracture criterion is used to evaluate the sticking or sliding state of jointed rock mass. The distribution of plastic zone at collapse state is determined. Numerical computational results show that the proposed procedure is effective to evaluate stability of jointed rock slope.

Excavation Program and Stability Analysis of High-Steep Rock Slope

Aimed to the problem of excavation and stability for a high and steep rocky slope, with the design excavation height of 90.23m, this paper grasped the engineering geological conditions and physical and mechanical properties of rock mass by such following methods as the field engineering geological survey, measuring, drilling sampling and laboratory test. Based on this, a comparative analysis of two different excavation ways was conducted using the large discrete element program-UDEC. The analysis included the stress-strain law and deformation failure trends of the slope when adopting slow excavation and steep excavation respectively. Moreover, the environmental damage caused by the two excavation ways was discussed. The results show that the slope has a better engineering geological condition and stability. In order to avoid disturbing hills and protect the natural environment, the steep excavation way is suggested for excavation and reinforcement of this slope.