Stability Analysis Of Soil Slope Research Articles

Efficient numerical implementation of limit equilibrium method for stability analysis of unsaturated soil slopes using Gaussian integral

Efficient numerical implementation of limit equilibrium method for stability analysis of unsaturated soil slopes using Gaussian integral

A Novel Multi-Objective Particle Swarm Optimized RF-SVR Model for Reinforced Soil Slope Stability Analysis

A Novel Multi-Objective Particle Swarm Optimized RF-SVR Model for Reinforced Soil Slope Stability Analysis

Optimal stability analysis of homogenous soil slopes with an irregular geometric morphology

The common morphologies of slope surfaces in nature include linear, stepped, convex, concave, and their combination types. Many researchers have investigated the stability of slopes with simple linear, stepped convex, or concave geometric morphologies, disregarding the effect of combination of convex and concave morphology. In this paper, slope surfaces with convex-concave characteristics are considered. A model of a slope surface composed of n segments is constructed to realize the arbitrary generation of irregular geometric morphologies. Based on the upper bound limit analysis and the log-spiral failure mechanism, a formula for the factor of safety of slopes with irregular geometric morphology is obtained. Optimal stability analysis of convex, concave and convex-concave combination slopes with different characteristics is carried out. This paper mainly focuses on the effect of the location and extent of convex-concave sections on slope stability and sliding surfaces. In addition, a comparative analysis is carried out from both theoretical and numerical perspectives. The local stability of convex and convex-concave combination slopes is discussed. The results show that the effect of convex-concave characteristics on slope stability is related to the equivalent straight-slope angle. Moreover, some abnormal phenomena have been identified. For example, under certain conditions, the stability of a convex slope is better than that of a straight slope, and a concave morphology is not conducive to slope stability. In addition, when the equivalent straight-slope angle is small, convex-concave combinations can yield the worst or best slope stability. Therefore, the location and extent of convex-concave sections should be comprehensively considered to achieve an optimal design scheme in slope reinforcement design and construction.

Stability analysis of unsaturated soil slopes with cracks under rainfall infiltration conditions

Pre-existing (open) cracks at slope crests, especially tension cracks, are a significant factor in the transition from shallow to deep-seated landslides in unsaturated soil slopes induced by rainfall. This paper presents an analytical framework to assess the stability of unsaturated soil slopes for deep-seated rotational failure considering arbitrary crack depths and unsteady infiltration, and its effectiveness is verified by previous literature and finite element analysis. A closed-form formula is proposed for the maximum depth of cracks in unsaturated soils by the stability of the vertical crack boundary. A parametric study is performed to investigate the impact of some key parameters on the stability of unsaturated soil slopes with cracks. Dimensionless stability charts are developed, which can calculate the factor of safety for the slopes with cracksof any depth and can reflect that the potential slip surfaces through or without passing through the crack tip. In addition, given the existence of a critical crack depth and maximum crack depth, with a ratio ranging from 0.5 to 0.6 based on the stability charts, deep-seated rotational failure is more likely to occur than failure caused by a crack boundary.

Stability of unsaturated soil slope considering stratigraphic uncertainty and rotated anisotropy of soil properties

AbstractThe stratigraphic uncertainty and rotated anisotropy of soil properties exist widely in nature. Recent studies have shown that the slope stability was significantly influenced by these two uncertainties. However, there is no proper method for simulating these two uncertainties at the same time, and the influence of the two uncertainties has not been considered in previous unsaturated soil slope stability analysis. This paper aims to propose a coupled method for characterizing the stratigraphic uncertainty and rotated anisotropy of soil properties, and investigate the unsaturated soil slope stability considering the two uncertainties. Through a slope case, the proposed method for characterizing the two uncertainties is examined. The effect of rotational angle on the slope stability and groundwater table is studied. In addition, four different uncertainty considerations are chosen to compare their influence on the slope stability and groundwater table. The results show that the proposed method can well characterize the two uncertainties at the same time. The rotational anisotropy of soil properties has a substantial impact on the slope stability and groundwater table. The rotational angles corresponding to the maximum and minimum reliability index of slope depend on the uncertainty considerations in the slope stability analysis. The slope reliability index only considering stratigraphic uncertainty is the highest, and the slope reliability index considering stratigraphic uncertainty and rotated anisotropy of soil properties is the lowest.

Shallow stability of soil slope with frame protection considering rainwater seepage: A calculation method

This paper introduces an integrated calculation method for analyzing the impact of frame protection engineering on the safety factor of shallow stability for soil slopes. The calculation method is based on the infinite long slope model, but it produces superior results by comprehensively taking into account the anti-sliding effect of the shallow slope sliding body. It combines the tension zone at the upper edge, the main sliding zone in the middle section, and the compression zone at the lower edge, while considering the anti-sliding force system of the frame protection structure and its contact surface with the soil. By converting the three-dimensional force system into a two-dimensional plane problem, an approximate calculation method for the shallow stability analysis of soil slopes with frame protection under rainfall seepage was established and numerically verified using the finite element method. The analysis indicates that the safety factor of the slope decreases significantly when seepage force is considered. As the length of the main sliding zone increases, the safety factor gradually decreases and approaches the result of the infinite long slope model. When the length decreases to zero, the safety factor gradually increases and approaches the result of the circular slip model. The use of frame protection significantly improves slope stability under rainfall seepage, and the safety factor increases with the number and embedded depth of the frame structure.

Stability of Unsaturated Soil Slope Considering Stratigraphic Uncertainty

Stratigraphic uncertainty is widely present in nature, but it has not been well considered in the stability analysis of unsaturated soil slopes in the past. In this study, the stability of the unsaturated soil slope is evaluated based on borehole data considering stratigraphic uncertainty. Firstly, an enhanced coupled Markov chain model is used to simulate stratigraphic uncertainty. Then, a finite element algorithm for automatically calculating the safety factor (FS) and the average groundwater table (AGT) of the unsaturated soil slope is developed. At last, a hypothetical slope located in the stratum from Perth, West Australia is analyzed using the proposed algorithm under different borehole schemes. The results show that with the increase in the borehole number, the statistics of FS and AGT will not monotonically increase or decrease. But the trend is that the mean values of FS and AGT gradually approach and eventually converge to the real values, and the standard deviations of FS and AGT decrease. There is a linear relationship between the standard deviation of FS (or AGT) and the average information entropy. The FS and AGT are negatively correlated considering stratigraphic uncertainty.

SPH approach for stability analysis of soil slope with variable permeabilities

A simulation framework based on meshless method has become an alternative numerical tool to model many deformation problems in geotechnical engineering. Large deformations in the failure zone can alter porosity, permeability etc., which in turn can affect the process of the failure. In this paper, a two-phase model in the framework of Smooth Particle Hydrodynamics (SPH) is introduced to model the interaction between water and soil through drag forces according to Darcy’s law. Changes in soil porosity and associated permeability are automatically adjusted within this framework. Firstly, two different problems i.e., flow through porous media and fluidized bed problem, are investigated to examine the suitability, and stability of the proposed SPH method. Then, the stability analysis of a soil slope under different water level conditions is performed with the strength reduction technique, and the groundwater effect of the slope is simulated. It is found that owing to the negative impact of seepage on soil slope, the horizontal displacement of the slope can be significantly larger. Afterwards, the influence of the variable permeabilities on the slope failure is investigated. The simulation results show that the change in permeability has a slight effect on the slope. Although the calculated safety factor does not change, the sliding distance differs by about 10%. The initial porosity has a large negative influence on the stability of the slope. The developed SPH model has been shown to be a valuable and effective tool for modelling complex problems that are challenging to be addressed with traditional approaches.

Assessing rainfall-induced wetting band depth for stability analysis of unsaturated soil slopes

Because of factors such as plant root action, soil capillary action, and evapotranspiration, the soil near the surface of a slope tends to be drier and in an unsaturated state. However, when rainfall infiltrates the soil, the soil near the surface can become saturated, creating a wetting band that may trigger shallow landslides on the slope. This study performed transient finite element seepage and slope stability analyses on unsaturated soil slopes during rainfall. The analysis considered a representative rainfall pattern observed in Taiwan from 2010 to 2022, accounting for potential impacts of climate change. The objective of this study was to explore the impact of wetting band development on the stability of unsaturated soil slopes under rainfall conditions. Additionally, the investigation aimed to analyze the variations in pore water pressure and volumetric water content throughout the rainfall process. These analyses were conducted to determine the slope safety factor and investigate the relationship between the wetting band and the potential sliding surface. The results showed that the soil pore water pressure and water content near the surface of the slope were highly influenced by rainfall. The wetting band gradually extended downward from the surface with increasing rainfall duration, resulting in an increased wetting band depth (WBD), while the potential sliding surface approached the slope surface. When the safety factor was at its lowest, the potential sliding surface intersected the edge of the wetting band and was included within the range of the wetting band. This observation indicates a significant relationship between the potential sliding surface and the evolution of the wetting band during slope failure at the moment of minimum safety factor. The study also observed that water infiltration near the toe of the slope was more rapid, leading to a deeper wetting band at this particular location.

Applying the strength reduction method to study of stability of residual mountains: A particular application

Due to huge disaster-caused force, seismic geological disasters primarily induce residual landslide, collapse and debris flow disasters with far higher hazard extent than that of earthquake disasters. Wherefore, this paper, with various vibration slopes caused by the most representative Wenchuan earthquake as research objects, introduces the strength reduction method to the stability study of residual mountains in a certain area, puts forward dynamic stability slope evaluation method based on dynamic and overall strength reduction method to obtain the mountain slope stability situation in the process of gradual instability, searches out the sliding surface of progressive expansion making use of dynamic strength reduction method and calculates dynamic safety index in the process of gradual slope instability pursuant to the calculation advantages of dynamic strength reduction method, so as to realize the analysis and regulation of the whole process of slope instability. The results show that in the stability analysis of a homogeneous slope, the safety index of slope stability calculated by strength reduction method is 6.7%, 8.8% and 10.5% higher than that calculated by finite element limit equilibrium method, Bishop method and Janbu method respectively. In the stability analysis of a multi-layer soil slope, the safety index of slope stability calculated by strength reduction method is 4.8%, 4.3% and 9.4% higher than that calculated by other three algorithms. While in the stability analysis of soft interlining slope, the safety indexes of slope stability calculated by the method proposed in this paper are increased by 26.10%, 29.11% and 26.46% respectively compared with other three algorithms, indicating that the stability of landslide residual mountains calculated by strength reduction method proposed in this paper is the highest.

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

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

Stability Analysis of Anchor-Reinforced Soil Slopes with Taylor’s Stability Chart

The stability of earth slopes can be enhanced by introducing an anchoring system. The factor of safety of an anchor-reinforced slope is one of the essential items required to evaluate stability. This parameter can be predicted using limit equilibrium and numerical approaches by relevant software. Taylor’s stability chart has been frequently used to estimate the factor of safety of an unreinforced homogeneous cohesive-frictional soil slope. An analytical expression was developed in this study based on the friction circle method by which the factor of safety of anchor-reinforced slopes can be predicted using Taylor’s chart. The anchor-reinforced slope considered in the analysis consisted of homogeneous cohesive-frictional soil. The analyses were carried out considering different slope inclinations, anchor loads, anchor orientations, and slip circles. An illustrative example explained the procedure for finding the factor of safety and showed how the developed method could be used by practicing engineers. A comparison between the factor of safety estimated by Taylor’s chart and the limit equilibrium method using SLIDE indicates a good agreement.

Research Progress on Stability Analysis Methods of Granite Residual Soil Slope

Based on the instability and failure of granite residual soil slope, this paper will introduce the stability of granite residual soil slope from theoretical research, indoor and outdoor simulation tests, and numerical analysis. Based on the review of previous work and the latest research results, the stability analysis of granite residual soil slope is discussed, and the main influencing factors of granite residual soil slope instability are summarized. The main factors are: its own disintegration property; The degree of microcracks in its internal structure.

Stability analysis of unsaturated soil slope considering softening and non-softening approach

In conventional geotechnical engineering practice, peak shear strength parameters are widely used in the design of geo-structures constructed with or within unsaturated soils. However, a reduction inshear strength from the peak to the residual value is typically observed during the shear deformation in typical fine-grained unsaturated soils. Several geo-structures in unsaturated soils undergo a large shear deformation prior to reaching the failure condition. Thus, the factor of safety of such geo-structures will gradually but significantly decrease with the development of the shear deformation. For this reason, the strain-softening behaviour of unsaturated soils should be considered for reliable design of the geo-structuresin unsaturated soils. In this study, an unsaturated clay slope under 10 years rainfall infiltration were modelled using softening and non-softening approach using commercial finite element software SIGMA/W. The responses of the studied slope to the long-term rainfall infiltration were analysed. The results of the softening and non-softening analysis were compared. This study provides valuable information with respect to the significance of the strain-softening that are useful in the rational design of slopes in unsaturated soils.

Utilization of Discrete Element Method in Multi-phase Soil Modeling for Soil Slope Stability Analysis

Utilization of Discrete Element Method in Multi-phase Soil Modeling for Soil Slope Stability Analysis

Stability analysis of homogeneous unsaturated soil slopes by using the variational method

Stability analysis of homogeneous unsaturated soil slopes by using the variational method

Three-Dimensional Stability of Unsaturated Excavation Slopes Under Different Seepage Conditions: A Case Study

Three-dimensional stability analysis of soil slopes remains a hot topic in the field of geotechnical engineering. Considering the fluid–solid coupling effect, this study performs a number of numerical analyses on the stability of a 3D excavation slope located in the Wuxi Taihu Tunnel, China. Three typical cases of the issued slope are investigated, i.e., the slope at the initial state, with the water-stop curtain, and with both the water-stop curtain and concrete-sprayed layer. The shear strength reduction method was adopted to determine the factor of safety (FOS) of the slope. The distributions of pore pressures and wetting lines, the horizontal and vertical displacements, and the critical slip surface are presented. The results indicate that the water-stop curtain can prevent the groundwater seepage effectively. The water-stop curtain and concrete-sprayed layer are effective in restraining the slope deformation, altering the critical slip surface, and improving the slope safety.

Non-equilibrium seepage characteristics and stability analysis of macroporous soil slope under water level changes

Non-equilibrium seepage characteristics and stability analysis of macroporous soil slope under water level changes

On the influence of dilation angle in soil slope stability analysis among other model parameters

Associated with slope stability, cohesion, and friction angle which are the most factors that can affect the slope failure, Investigation studies in geotechnical structure analysis establish that the dilatancy angle, y, is rarely acceptable in slope stability analysis, and when it considers the process is poorly sophisticated and simplistic. The paper describes two numerical slope stability analyses of a homogeneous soil with a plane strain model, to study the influence of dilation angle through different friction angle ranges (20, 25, and 30). The analysis used an immutable friction angle with variable dilation angle, results show that the safety factor increases gradually with the increase of dilation angle and dramatically decreases when the dilation angle is close to the friction angle, which means the dilation angle, y, affect the safety factor through slope analysis. It is very significant to check out the scrupulous value of dilation angle, y, when dealing with associated and non-associated soil parameters. In geotechnical and thermal analysis, dilation angle can affect the volume change as well as a safety factor.

Numerical Analysis of Time Fractional-Order Unsaturated Flow and Its Application

Numerical simulation of unsaturated flow process is of great significance to many fields such as soil slope stability analysis and migration simulation of underground pollutants. Generally, it is widely used due to the universal applicability of Richards equation, but the seepage process described by Richards equation does not consider the anomalous diffusion phenomenon in natural environment and experiments. In response to this problem, this paper combines the Caputo derivative to obtain the time fractional Richards equation with broader seepage significance. Then the finite difference method is used to obtain the discretization scheme and the Picard method is used to solve it iteratively, and the sensitivity analysis of the fractional parameters and soil-water characteristic curves is carried out. Finally, combined with the experimental data of soil column infiltration, the numerical solutions obtained by the time fractional Richards equation under different soil-water characteristic curves are compared. The results show that the time fractional Richards equation of the VGM model has a better fitting effect with the measured data and can better describe the seepage process of groundwater in unsaturated soil.