Slope Stability Analysis Method Research Articles

Stability Analysis of Seismic Slope Based on Relative Residual Displacement Increment Method

The seismic stability analysis of a slope is a complex process influenced by earthquake action characteristics and soil mechanical properties. This paper presents a novel seismic slope stability analysis method using the relative residual displacement increment method in combination with the strength reduction method (SRM) and the actual deformation characteristics of the slope. By calculating the relative displacement of the key point inside the landslide mass and the reference point outside the landslide mass after each reduction, the safety factor of the slope is determined by the strength reduction factor (SRF) corresponding to the maximum absolute value of the relative residual displacement increment that appears after a continuous plastic penetration zone. The method eliminates interference caused by significant displacement fluctuations of key points under earthquake action and reduces the subjective error that can occur when manually identifying displacement mutation points. The proposed method is validated by dynamic calculations of homogeneous and layered soil slopes and compared with three other criteria: applicability, accuracy, and stability.

Seismic Reliability Analysis of an Excavation Slope Based on Direct Probability Integral Method

China, situated in the circum-Pacific seismic belt, experiences frequent seismic activity and faces diverse geological conditions, making structural stability of paramount importance, especially under seismic conditions. The majority of current earthquake generation methods do not consider the nonstationary nature of earthquakes. This paper introduces a spectral representation-random function model for generating nonstationary earthquakes, effectively simulating stochastic seismic ground motion. Furthermore, traditional slope stability analysis methods are deterministic and incapable of providing probabilistic assessments of slope instability. Therefore, this paper proposes a unified framework for static and dynamic structural reliability analysis based on the direct probability integration method, quantifying the impact of stochastic seismic ground motion on the dynamic reliability of slope stability. Finally, the proposed methods are applied to an excavation slope in Nanjing, using sliding displacement and safety factors as evaluation criteria to study the reliability of the slope under the influence of stochastic seismic events.

ANALYSIS OF LIMESTONE QUARRY SLOPE STABILITY, NIMBOKRANG DISTRICT, JAYAPURA REGENCY, PAPUA, INDONESIA

Slope stability analysis generally uses the concept of factor of safety (FoS) value using several whole rock parameters. The slope stability analysis method that will be used in this research is the slope stability analysis method in open pit mines based on rock mass classification with the Rock Mass Rating (RMR) system and the Geological Strength Index (GSI) system and analyses the potential for landslides that can occur on slopes at that location with kinematics and limit equilibrium methods so that the type of landslide can be determined based on the intensity of the geological structure on the slope of the CV. Inti Jaya open pit limestone mine, in Wahab Village, Nimbokrang District, Jayapura Regency. This research aims to provide information on the current condition of the slope whether it is by safety standards, make slope engineering improvements and redesign safe slopes if unstable slope conditions are found. Research on the stability of limestone slopes begins with the collection of field data and rock samples. Furthermore, sample testing was carried out to obtain physical and mechanical properties and weighting of rock masses, which were then analysed to obtain the characteristics and quality of rock masses that would be applied using the finite element method with Slide 6 from Rocscience to determine the Factor of Safety (FK) and the design of safe slope geometry. The RMR value for slope 1 is 62, slope 2 is 61, and slope 3 is 62. So it can be concluded that the rock is included in rock mass class 2 with good quality. Based on the analysis of potential avalanche types, the three slopes have non-arc avalanche types. From the analysis carried out using Rocscience Slide 6.0 software, the FoS value for slopes in original, dry, and saturated conditions is obtained, where on slope 1: FoS in original conditions is 0.935, FoS in dry conditions is 1.619, and FoS in saturated conditions is 0.671. Then slope 2: FoS in original condition is 0.896, FoS in dry condition is 1.457, and FoS in saturated condition is 0.806. Slope 3: FoS in original condition is 3.490, FoS in dry condition is 4.199, and FoS in saturated condition is 3.368. So it can be concluded that slopes 1 and 2 are unsafe or unstable in original and saturated conditions so that landslides can occur. In the analysis of the FoS value of the actual condition of the slopes in the field using the Hoek & Brown method, the FoS value of slope 1 is 0.387, the FoS value of slope 2 is 0.579, and the FoS value of slope 3 is 1.272, it can be seen that the actual condition of the slopes in the field is slopes 1 and 2 in an unsafe or unstable state. Improvements must be made to the slope geometry to maintain the stability of the slope to remain safe or stable. The recommended improvement is to create a new working level for slopes 1 and 2, with steep height and large rock porphyry.

Stability analysis and evaluation of a highway slope in the high and cold mountain area and suggestions for prevention and control

In order to ensure the stability of a rocky slope on a highway in a high cold mountainous area, this paper evaluates the stability of the right high slope in the section from K155+320 to K155+460 using the Chi Ping projection method and the fuzzy evaluation method based on game theory-cloudified object model. Firstly, the geological, geomorphological, hydrological and other natural profile information of the slope is obtained through field investigation, and these indicators are transformed into evaluation indicators for qualitative evaluation using the Chi Ping projection method. Then, the fuzzy evaluation method based on game theory-cloudified object model is used to transform the qualitative evaluation results into quantitative data, taking into account the mutual influence between different factors. The results show that the results obtained by the two evaluation methods are consistent. Finally, based on the stability analysis and evaluation results, it is proposed to use the method of clearing the surface dangerous rocks and applying active protective nets to deal with the slope problem in that area. At the same time, the slope stability analysis and evaluation method and the prevention and control suggestions provide reference for the subsequent slope governance.

Meshless numerical manifold method with novel subspace tracking and CSS locating techniques for slope stability analysis

The meshless numerical manifold method (MNMM) inherits the advantages of handling continuous and discontinuous problems uniformly, improving interpolation precision, and avoiding linear dependence issues. This paper refines the MNMM method for slope stability analysis to overcome the dependence and sensitivity of the strength reduction method of the finite element method on the number of finite element meshes and the algorithm for solving the nonlinear equations when calculating slopes with soft and weak interlayers. First, the strength reduction method (SRM) was incorporated into MNMM to create the numerical model called MNMM-SRM. Based on the MNMM-SRM, a complementary Mohr-Coulomb (M−C) control equation compliant with Koiter's rule of multi-yielding surfaces was established. In the principal stress space, the subspace tracking method was used to track the eigenvalues and eigenvectors of the stress tensor, thereby addressing the corner problem of M−C multi-yield surfaces. Combining the k-means clustering algorithm with wavelet transformation and employing the slope's total nodal displacement field as an input variable, an intelligent and efficient critical slip surface (CSS) automatic extraction method was developed. Three typical cases were used to validate the accuracy of the numerical model. This numerical model has a wide range of potential applications in slope stability research.

Slope stability analysis using probabilistic approach

Monte Carlo simulation is a method for calculating a deterministic model iteratively using sets of random numbers as inputs, it’s was used widely in probabilistic analysis of slope stability determining the minimum safety factor and predicting of slope instability. This paper presents a method of slope stability analysis based on the Hovland method and using the Monte Carlo simulation that defined two parameters as random variable, the cohesion and the friction angle of the soil. In order to evaluate the efficiency and applicability of the proposed method, an example of a slope located in northern Morocco is presented in this study. The results show that the minimum safety factors calculated in this study are very close to those obtained by other researchers, which also revealed that the present method could be applied to predict the stability of homogenous slopes.

Three-dimensional strength reduction and two-dimensional limit equilibrium methods of slope stability analysis

Landslides caused tremendous damage to the life and properties of society. In this study, cut slopes were analyzed using the two-dimensional (2D) limit equilibrium method (LEM) by slope/w software and a three-dimensional (3D) strength reduction method (SRM) by using Fast Lagrangian Analysis of Continua in 3 Dimensions (FLAC3D), which is a finite difference method (FDM) numerical software. Analysis of the slope is done by representative soil samples collected and transported to the laboratory to determine input parameters like unit weight (γ), shear strength parameters (c,φ), and the water level position. Strength parameters were determined from direct shear tests for cohesionless soil and consolidated undrained (CU) triaxial tests for cohesive soils. For 2D analysis, the factor of safety (FOS) was calculated for the condition of dry and maximum water levels using Morgenstern-price methods, and the analysis gave FOS 0.743 and 0.614 for the dry and maximum water level conditions, respectively; for SRM, the input parameters of bulk and shear modulus (B, G) which were determined from the empirical equation using modulus of elasticity(E) and Poisson's ratio(ʋ).Moreover, ʋ were adjusted according to the principle of φ-v inequality. For 2D analysis, FOS were 0.743 and 0.614 for dry and maximum water levels using Morgenstern-price methods, whereas 3D analysis gave FOS 0.34 and 0.31 for dry and maximum water levels, respectively. From the analysis, it is concluded that 2D LEM is given higher FOS than 3D FDM. Moreover, the 3D analysis showed that velocity and displacement in the lateral Y direction were minimal and maximum in the horizontal X direction. The maximum horizontal velocity for the respective dry and maximum water level conditions gave 6.64*10−4 m/step and 6.04*10−4 m/step and maximum horizontal displacement 7.36 m and 6.06 m for dry and maximum water levels, respectively.

Mapping submarine landslides susceptibility in continental slopes with rich gas hydrates

Gas production from oceanic hydrates could trigger large submarine landslides. To screen out the sites susceptible to perturbation, this paper proposes a physically-based model for assessing the susceptibility of submarine landslides in continental slopes where gas hydrates are widespread. The model does not require an inventory of historical submarine landslides that are often incomplete or unavailable. Instead, the model is derived within the framework of the limit equilibrium method of slope stability analysis, and accounts for pressure buildup and decreasing cohesion in the slope due to hydrate dissociation. The proposed model is then employed to map the landslide susceptibility of a study area conditioned to a hypothetical scenario of seafloor warming that triggers hydrate dissociation. The susceptible zones are found in the regions with shallow water and high geothermal temperature. Unlike the terrestrial landslides, the slope angle plays a secondary role in affecting the susceptibility of submarine landslides triggered by hydrate dissociation, while the hydrothermal conditions are important factors that control the susceptibility.

Slope stability assessment of some waste rock dumps at a typical gold mine in Ghana

Mining results in both economic and uneconomic materials being generated. The uneconomic materials (wastes) are stacked in a convenient place for further use or stored permanently as a slope or embankment. In Ghana, a typical gold mine set up dumping sites to accommodate the waste generated from its operations. Samples were collected from three waste dumps and tested in the laboratory, and the parameters obtained were used as input for 2D model development. The Factor of Safety (FS) of the three waste dumps were determined using the Janbu Generalised slope stability analysis method. Path and slope surface (circular and non-circular) search methods were used for the three cases. The FS for the waste dumps were determined and ranged from 1.61-2.74, 1.49- 2.50 and 1.32-2.10 under dry, static and pseudo-static loading conditions, respectively. These values exceed the minimum requirements of 1.1-1.5 for stability conditions. The geometry of the waste dumps, Suraw Waste Dump (SWD), is within the standard and hence, does not require reshaping, while the slope angles for the remaining waste dumps, Tano Waste Dump (TWD) and Akoti Waste Dump (AWD) need to be reshaped to achieve the proposed slope angle of 3H:1V (18.40 degrees) as stipulated in the mine’s Environmental Impact Statement (EIS).

A three‐dimensional limit equilibrium method for slope stability analysis integrating machine learning optimized intercolumn force function

A calculation of the safety factor is the basis of slope stability analysis. The three‐dimensional (3D) limit equilibrium method is one of the most effective safety calculation methods, and ignoring the partial shear force between columns is the most common calculation assumption, which will lead to an unreasonable safety factor. By constraining the range of the intercolumn shear function and the position of the action point of the force between columns and integrating machine learning to optimize the net moment of the column, the simulated annealing algorithm is used to obtain the intercolumn shear function under the minimum net moment, and the safety factor is calculated by using boundary conditions. Finally, proving the accuracy of this method by calculating two examples of commonly used slopes. Example A verifies that the result of the proposed method is more conservative than that of other 3D calculation methods and that the coordinates of the action point of the intercolumn forces in the and directions have little influence on safety factor. Example B verifies the applicability of this method to various slope forms. This method fully considers the stress of soil under actual conditions, making the calculation results more reasonable.

Calculation of Risk Probability of Levee Landslide Based on Three-dimensional Lequilibrium Theory

Sliding instability is a common form of failure of embankments, and traditional dike safety evaluation often uses the safety factor value to judge whether it is safe or not. However, due to the uncertainty of the rock and soil characteristics of the embankment, the evaluation results of the safety factor method sometimes fail to reflect the reality, and it is reasonable to use the risk analysis of sliding instability considering these uncertainties. In this paper, the uncertainty of rock and soil strength parameters and the randomness of seepage field are considered, and the risk probability of sliding instability of the embankment is solved by relying on the reliability analysis method. In the reliability analysis, a three-dimensional bin method combining slope stability analysis and gradient optimization method of reliability analysis are proposed, which consider the safety performance, so that the stability evaluation is not too conservative, and the corresponding sliding risk probability can be obtained while obtaining reliable indicators. Finally, the calculation program is prepared for the proposed method, and the proposed method is verified to be reasonable and correct through the example.

Double Strength Reduction Method for Slope Stability Analysis Based on Water Content Variation: A Study and Engineering Application

Soil moisture content changes caused by rainfall and other factors can significantly affect slope stability and potentially lead to geological disasters, such as landslides and debris flows. However, conventional finite element methods for strength reduction do not consider the impact of water content on slope stability. This paper examines classical finite element methods for reducing the double strength coefficient and then introduces a novel approach using changes in moisture content. The new method is implemented through the use of an ABAQUS FE program’s USDFLD user-defined subroutine. This paper concludes by contrasting the outcomes derived from the limit equilibrium technique and other techniques and verifying the accuracy of the suggested approach through theoretical and numerical simulations. The numerical calculations for the stability evaluation of the Azhuoluo slope in the Chinese province of Guizhou, Shuicheng county were performed utilizing the ABAQUS FE platform’s USDFLD user-defined subroutine based on the double-strength discounting method, in response to the large landslide disaster in the region. The results show that the red clay, formed from the weathering of basalt in the area, experiences asynchronous decay in both friction angle and cohesion as the water content increases, with a significantly higher decay rate in the internal friction angle compared to cohesion. This indicates that traditional finite element methods that synchronously discount the internal friction angle and cohesion do not correspond to reality, whereas this proposed double-strength discounting method, based on water content changes, accurately reflects the essential characteristics of slope instability and has clear physical meaning and practical engineering applications.

A stress-based limit method for three-dimensional soil slope stability analysis

A stress-based limit method for three-dimensional soil slope stability analysis

Evaluating the dynamic response and failure process of a rock slope under pulse-like ground motions

Earthquake-induced landslides represent a significant proportion of seismic hazards in mountainous areas. Numerous slope stability analysis methods exist; however, only a few consider the interactions between pulselike seismic waves and landslides. This study investigates the seismic response characteristics of a homogenous step-like slope to evaluate the acceleration ground motion amplification along the surface. Parametric analysis focusing on the effect of pulselike waves on the slope is conducted using the finite difference modeling code Flac 3 D. Based on the numerical simulation results, pulselike seismic waves greatly influence the acceleration and velocity amplification factor (MPGA & MPGV), with maximum amplification usually obtained at the slope’s crest, where sliding failure initiates. The MPGV of rock slope under pulselike seismic waves is 9.3% higher than near-fault non-pulselike and 16% higher than the far-fault. The displacement for pulselike seismic waves is 20% higher than non-pulselike waves. The dynamic failure analysis presented deep failure for the slope under pulselike seismic wave compared to the non-pulselike. The dynamic failure calculated using Flac 3 D agrees with the results of Newmark-type displacement, with a marginal error between 1 and 8%. The study’s findings can be factored into reinforcing seismic engineering design and probabilistic stability analysis.

Changes in Slope Stability over the Growth and Decay of Japanese Cedar Tree Roots

In Japan, repeated driftwood landslide disasters have become a major issue; thus, studies are required to better understand forest function to implement appropriate forest management and prevent such disasters. We investigated the effect of Japanese cedar tree roots on shallow landslide initiation. To incorporate the effect of roots on the two side-flanks of the shallow landslide, we propose a new slope-stability analysis method in which the sliding block is simplified as a three-prism model. The root reinforcement was approximated by the sum of the root pullout forces over a unit area, incorporating changes in the root strength with the growth of the trees after planting and the decay of the stumps after cutting. The reinforced root strength after the stump-cutting decreased linearly with time, with no strength remaining at 9 years. In contrast, the reinforced root strength of the new plants increased according to a logistic curve with time; thus, the root strength increased only slightly up to 9 years after planting, and the minimum total reinforced root strength was observed at this time. The safety factor of the slopes in a forest basin in Ibaraki Prefecture was calculated using the proposed three-prism method at intervals of 5 years on a 1-metre-resolution digital elevation model. The number of unstable grids peaked at 10 years, and a higher risk of slope instability was observed at 5–15 years. Therefore, implementing forest operations for lowering slope instability during this period should be important to prevent landslide disasters.

Comprehensive Analysis Method of Slope Stability Based on the Limit Equilibrium and Finite Element Methods and Its Application

Comprehensive Analysis Method of Slope Stability Based on the Limit Equilibrium and Finite Element Methods and Its Application

INFLUENCE OF SURFACE CRACKS ON THE STABILITY OF CRACKED SOIL SLOPE

The slope stability is a major concern to geotechnical engineers. Traditional methods of slope stability analysis have potentially ignored the influence of surface cracks. It is also known that seasonal rainfall and seepage through crack are closely related with slope failure. First, surface cracks provide special flow channels which increase the soil permeability and decrease the soil strength. Second, water-filled cracks apply an additional active force on the slope. Finally, cracks can create a part of the critical failure surface that has no shear strength. The objective of this paper is to investigate the influence of existing cracks on the stability of a cracked soil slope in different state. The effects of crack depth, slope angle and water-filled cracks on the stability of the cracked slope are explored. The analysis was conducted using the computer modelling programs Optum G2 to analysis of slope factor of safety. The results show that with increasing of slope angle the factor of safety decreases and this problem is significant in the slope with water filled cracks. Also, Factor of safety for all of slope angles in Dry and water filled cracks states with increasing the crack depth, decrease significantly.

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

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

Slope Stability Analysis Method of Unsaturated Soil Slopes Considering Pore Gas Pressure Caused by Rainfall Infiltration

The variation of pore gas pressure caused by rainfall infiltration is an important factor that leads to slope failures. The purpose of this study is to propose a new slope stability analysis method that considers pore gas pressure and examines the effect of airflow on slope stability by using a numerical method. A water-air two-phase flow analysis was conducted to investigate the distribution of pore air pressure, pore water pressure, and water saturation triggered by rainfall infiltration. Then the variation of the load resulting from pore gas pressure was incorporated into the slope stability analysis method based on the unsaturated soil shear strength theory and the residual thrust method to simulate the influence of airflow on the Tanjiahe landslide in China. In order to study the infiltration behavior with respect to initial saturation, water and gas flow analyses were performed considering various initial states of saturation under similar settings. Results showed that the pore gas pressure between the slope surface and the slip band clearly varied and that it decreased during the process from the slide bed to the deep direction. Then, the pore water pressure formed in the saturated zone was transferred by the airflow to the slope toe. As a result, because the pore gas pressure gradient increased the thrust of the slide mass, the safety factor decreased over time. Moreover, in the first step, the magnitude of infiltration decreased with an increase in initial saturation, while when the magnitude dropped to the minimum value, it then went up with an increase in initial saturation. The maximum value was usually reached at a saturation degree of 0% or 100%. When evaluating slope stability, the safety factor obtained by the slope stability analysis method that considered the water-gas coupling effect was much lower than when it was not considered during the process of a similar seepage. The impact on the slope failure was significant and may provide a practical reference for hazard assessments to control rainfall-induced landslides.

Improved Statically Solvable Slice Method for Slope Stability Analysis

Improved Statically Solvable Slice Method for Slope Stability Analysis