Slope Stability Problems Research Articles

Binary composite crossover genetic algorithm for locating critical slip surface

Solving slope stability problems requires determining the critical slip surface (CSS) of a slope and its corresponding minimum factor of safety (Min. F), and determining the CSS is a complex optimisation problem. In this paper, we propose a real-coded binary composite crossover genetic algorithm (RGA-BCC) to locate the CSSs of slopes. A reasonable combination of parameters for the binary composite crossover (BCC) operator in the RGA-BCC is determined through six benchmark function experiments. On this basis, the stability of five soil slopes from the literature was analysed using the RGA-BCC in combination with the Morgenstern and Price method, and the results obtained were compared with those in the published literature to demonstrate that the RGA-BCC is able to efficiently determine the CSSs of slopes and their minimum factors of safety. The results of the sensitivity analyses show that having a reasonable setting for the number of control variables is the key to effectively determining the CSS. Moreover, the effects of slope structural characteristics should be considered when setting the number of control variables and population size. Algorithm comparison results show that RGA-BCC has better performance in solving the slope CSS problem compared with differential evolution (DE) and sparrow search algorithm (SSA).

Research on Mechanical Characteristics of High-Toughness Anti-Slip Pile Based on Slope Anti-Slip Stability Enhancement

Aiming at the problem of insufficient slope stability in deep foundation pit engineering, this paper takes the integrated urban and rural water supply project in Lingao County as the research object, simulates and analyzes the landslide process of the slope by using the strength discount method, and explores the mechanical response characteristics of the anti-slip piles in depth. It is found that the traditional anti-slip pile is prone to early failure due to bending and tensile damage in the middle of the pile back, which leads to the decline of slope stability. For this reason, this paper designs and studies the high-toughness anti-slip pile material and carries out numerical simulation analyses on C30 concrete anti-slip piles and high-toughness concrete anti-slip piles, respectively, for 9 working conditions, for a total of 18 working conditions. The results show that the bending and tensile toughness and strength of the anti-slip piles are significantly improved by using high-toughness material, which effectively avoids bending and tensile damage, and the slope safety coefficient is increased by 32.10%. Furthermore, the optimized design of anti-slip piles in terms of material, pile length, and pile position can effectively improve the stability of slopes and prolong the service life of the anti-slip piles, which provides a new way of thinking and methodology for the safety design of the deep foundation pit project. Thus, this study has important theoretical significance and engineering application value.

Assessment of Slope Stability at Erbil Citadel, Kurdistan Region of Iraq Using Bejerman’s Method

The Erbil Citadel is located in the center of Erbil City; the capital of the Kurdistan Region of Iraq. The shape of the citadel is a large, oval hill. The Citadel was inhabited more than 6,000 years ago and is thought to be one of the longest-continuously inhabited sites in the world. Therefore, the Citadel was announced in 2014 as a World Heritage by UNESCO. The height of the Citadel is not uniform; it ranges between (28–30) m, the top elevation is 429 m (a.s.l.), whereas the bottom elevation ranges between (407– 416) m (a.s.l). The Citadel has an oval shape with diameters between (350 – 420) m, the E–W being the longest. The slopes of the Citadel (Tell) display severe erosion and slope stability problems, the main types are creep, which can endanger the existing historical buildings, especially on the edges of the Citadel. Different data about the Citadel have been reviewed but couldn’t find special studies concerning the slope stability of the Citadel. Therefore, we have applied Bejerman’s method, which is a quick field method to assess the slope stability of the slopes of the Citadel to find the Landslide Possibility Index (LPI). Eleven stations were selected around the Citadel to apply Bejerman’s method, the stations were selected in the site; wherever clear indications were found for slope instability. The results of the assessment showed that the LPI ranges between 18–22, which means grade IV, and Failure possibility of Medium (2 stations), and High (9 stations). Recommendations are given to keep the slopes of the citadel as safe as possible.

Application of sparrow search swarm intelligence optimization algorithm in identifying the critical surface in slope-stability

The use of nature-inspired meta-heuristics to tackle complex optimization problems is steadily gaining popularity within a rapidly evolving world. Swarm intelligence (SI) optimization motivated by behavior of community-based organisms of flocks of birds, schools of fish, colonies of ants and bees performs the search through agents whose trajectories are primarily adjusted stochastically and sporadically deterministically, by golden rules drawn from Mother Nature. Each entity within the swarm is swayed by its individual ‘best’ and group’s ‘best’ position while moving randomly to converge to optimal through competition and cooperation. The sparrow search algorithm (SSA), developed by Xuea and Shen (Xue and Shen in Syst Sci Cont Eng 8:22–34, 2020) is a very recent SI approach that adopts the sparrow producer–scrounger model metaphorically for designing optimum searching strategies, inspired by the foraging, anti-predation behavior, and the overall group wisdom of sparrows. SSA has been experimented on some hard benchmark test functions to test its effectiveness and thereafter, applied in slope-stability problems in searching the critical failure surface. The objective function to be optimized is the factor of safety against failure given by Bishop's (Bishop in Geotechnique 5:7–17, 1955) simplified method. Results show SSA is a strong contender to bio-inspired methods like genetic algorithms, big-bang big-crunch, simulated annealing, and artificial bee colony algorithms. The study illustrates the flexibility, efficiency, and robustness of the methodology in function optimization.

Study of Slope Stability of the Mining Wall in an Open-Pit Coal Mine by the Paste Cut-and-Backfill Method

According to this study’s findings, slope stability problems in open-pit coal mines can be avoided, and mine wall collapse can be effectively mitigated by the use of cut-and-backfill mining techniques. The main research results are as follows: (1) The stope and waste rock’s geotechnical, physical, and mechanical characteristics were gathered and examined; the geotechnical and mechanical characteristics found in this study largely satisfy the criteria for slope stability analysis. (2) Cemented paste backfill (CPB) materials were made of mine waste rock and fly ash at a desired ratio, mixed with cement as a bond material, and were tested in the laboratory, using a combination of cement percentages of 6%, 8%, and 10% for the cement content and 25%, 30%, 35%, and 40% for the fly ash content, to determine the ideal mix for artificial ground support in underground mines, taking into account both economic and performance factors. (3) By using this model, the changes in CPB strength were investigated under various factors influencing the cement ratio, and limit equilibrium modeling was used with the FLAC-Slope 8.1 program with different cement paste backfill ratio to calculate the factor of safety for each cement percentage after 1 day, 3 days, 7 days, and 28 days of curing time (CT) to obtain the optimum compressive strength and shear straight of cemented paste backfill with high paste fill shear strength on the slope. (4) The research results are of great significance for the safety of important facilities in open-pit mines and provide a basis for the design and safety implementation of open-pit slope engineering.

Application of new technologies to enhance the stability of high embankment slopes

This study aims to investigate the stability problems of high road embankment slopes in the Republic of Moldova, revealing shortcomings of classical methods. The authors propose a solution by using the RG system, equipped with specialized vibration drilling equipment from "RTG RAMMTECHNIC Gmbh". The method provides for the creation of piles in deep boreholes using the vibrating d, filling the cavities with soil, with subsequent compaction of soil in stages. Experimental field and laboratory research has demonstrated the effectiveness of this method. The results showed significant improvements in soil properties: increased density, strength, and deformation characteristics. The proposed technology offers advantages such as: increased load-bearing capacity of the soil-pile massif, practically complete elimination of dynamic effects on the ground and structures located in close proximity to the construction site, reduced manual labor costs, and a decrease in the overall cost of the construction work. The study aimed the application of this method in Moldova's road construction, highlighting its potential to counteract slope deformations caused by the action of various factors of any nature. The authors suggest the need for further research for refine the methodology, assess economic feasibility, and perform stress-strain analysis using the Finite Element Method. The study was concluded by outlining plans for future research on embankment slopes stabilized by soil piles using the RG installation.

Stability analysis of ultra-high and steep reinforced soil fills slopes based on strength reduction

The research focuses on solving the important problem of slope stability in the field of civil engineering. The study adopted an advanced strength double reduction coefficient method for slope stability analysis, which considers the different influence weights of cohesion and internal friction angle, and reduces them with different reduction coefficients to describe the stability of the slope. The simulation experiment results indicate that the attenuation degree of cohesion and internal friction angle affects slope stability. When the reduction coefficient of cohesion increases to 1.737 and the reduction coefficient of internal friction angle increases to 1.201, the slope is prone to instability and failure, and the safety factor of the calculated result is 1.493. Moreover, when the anti-slip pile is set in the middle of the slope (1/2), and the slope is in a critical state, the bending moment and shear force suffered by the anti-slip pile are both maximum, so the reinforcement effect is also the best.

A Generalized Limit Equilibrium-Based Platform Incorporating Simplified Bishop, Janbu and Morgenstern–Price Methods for Soil Slope Stability Problems

Limit equilibrium (LE) method is the most widely used method for slope stability analysis. Different methods based on the LE technique for the analysis of the stability of the slope have been developed. Some are based on satisfying the force equilibrium condition of the failing mass (Janbu’s method), while some focus on satisfying the moment equilibrium condition (Bishop’s method). Among these methods, the most accurate result is provided by the Morgenstern–Price method as it not only satisfies both moments as well as a force equilibrium condition but also considers the interslice shear forces (Vi) and interslice normal forces (Ei), which are neglected by most of the LE methods to avoid the condition of indeterminacy. To accommodate these forces, Morgenstern–Price (MP) gave a relation between the Vi and Ei which depends upon a scaling multiplier (λ). Thus, it becomes necessary to evaluate λ value along with the factor of safety (FS). There is barely any work discussing the detailed methodology of evaluation of λ along with FS. Method for obtaining λ along with FS have been developed and elaborated in details here. While calculating FS (MP method), evaluation of Ei is a must which is dependent upon the values of normal force at the base of each slice (Ni) and FS, which itself is dependent upon the value of Ei, making it a loop of interdependent variables. To avoid this interdependency of above stated variables, a separate formulation of Ei is given which reduces the calculations (run-time) involved. A VBA code-based platform has also been developed incorporating the generalized LE method, including Bishop’s, Janbu’s, and Morgenstern–Price methods which are represented in the form of flowcharts in this work.

Flood Analysis on Lake Tempe, South Sulawesi

Tempe Lake is one of the largest lakes in Wajo, Sopen, and Siddenreng Rappang in southern Sulawesi. Lake Tempe is the reservoir of his five major rivers: Bilokka, Lidaratangu, Masaka, Siddenreng, Bira and Walane. The lake offers many benefits to the community such as securing water resources, flood control, agriculture, fishing, and tourism. However, approximately 20–40 cm of silt is produced annually. This can cause flooding in the surrounding areas. Therefore, the restoration of Lake Tempe is necessary to mitigate flooding caused by continuous sedimentation. The Department of Public Works and Housing has developed a phased dredging plan to improve the capacity of Lake Tempe. Later, as no disposal sites were available, dredged materials were used to build several artificial islands along the perimeter of the lake. After the reconstruction project was completed, two major floods occurred, overtopping embankments. Therefore, the design analysis of embankments is required. Analysis indicates that two flood events occur, with a 20-year return period flood and a 50-year return period flood at elevations of 8.36 m and 9.2 m. From hydraulic analysis it is found that flood embankment height of 10 m is overtopped by water level of total 9.56 m and 10.4 m respectively because of wave run up. For a 20-year return period, there is an indication that slope stability and settlement problems affect flood events. It can be concluded that flood problems occur because of extreme events and the failure of flood embankments due to overtopping.

The Influence of Rock Slope Scales of Joint Network and Slope Height on the Stability and Failure Mechanisms

This paper demonstrates the influence of slope geometry and scale of the joint networks on the stability and failure mechanisms in discontinued rock masses. These analyses are based on the finite element method (FEM) to calculate the factor of safety (FOS) and to simulate the explicit discontinuity deformations for different scales of rock masses. The study was carried out through examples of regular jointed models having different slope heights and irregular jointed dry rock slopes. Joints usually decrease the strength of the slopes and suggestively increase slope stability problems. The result shows that the slope stability decreases with increased block size and shape and that the irregular columnar joints are more unfavorable to the slope stability than the regular joints. Furthermore, with dropping the factor of safety and randomly distributed joints the rock failure mechanism appears to shift from structurally controlled for the 50 m slopes towards a step-like failure path for the 100 m and 200 m slopes.

Hybrid algorithm for global optimization based on periodic selection scheme in engineering computation

PurposeMetaheuristic algorithms based on biology, evolutionary theory and physical principles, have been widely developed for complex global optimization. This paper aims to present a new hybrid optimization algorithm that combines the characteristics of biogeography-based optimization (BBO), invasive weed optimization (IWO) and genetic algorithms (GAs).Design/methodology/approachThe significant difference between the new algorithm and original optimizers is a periodic selection scheme for offspring. The selection criterion is a function of cyclic discharge and the fitness of populations. It differs from traditional optimization methods where the elite always gains advantages. With this method, fitter populations may still be rejected, while poorer ones might be likely retained. The selection scheme is applied to help escape from local optima and maintain solution diversity.FindingsThe efficiency of the proposed method is tested on 13 high-dimensional, nonlinear benchmark functions and a homogenous slope stability problem. The results of the benchmark function show that the new method performs well in terms of accuracy and solution diversity. The algorithm converges with a magnitude of 10-4, compared to 102 in BBO and 10-2 in IWO. In the slope stability problem, the safety factor acquired by the analogy of slope erosion (ASE) is closer to the recommended value.Originality/valueThis paper introduces a periodic selection strategy and constructs a hybrid optimizer, which enhances the global exploration capacity of metaheuristic algorithms.

Different aspects regarding slope stability improvement using piles

The problem of slope stability is a common one in the field of geotechnical engineering. There is more than one method that can be adopted in order to improve the stability of a slope. During the last decade, using piles for improving the mechanical behaviour of slopes has become the main approach of dealing with unstable slopes. In the current paper, the stability of a slope was analysed by using the tridimensional finite elements method using different scenarios of consolidation with timber piles. A parametric analysis was carried out for two different slopes: sand slope and soft soil slope. There were also analysed two different constitutive models: Mohr-Coulomb and Hardening Soil Small with different location of the consolidation system. The stability analyses employed both timber piles and concrete piles which were modelled in Plaxis 3D software by using two different approaches: embedded piles and volume piles. In the end, the most favourable position for the pile consolidation system is highlighted in order to attain the maximum stability of the slope. Also, different aspects of the constitutive models, modelling the piles and pile material are discussed from the point of view of slope stability improvement.

Diffusion mechanism of cement-based slurry in frozen and thawed fractured rock mass in alpine region

The problem of slope stability after freeze-thaw damage in cold regions has become increasingly prominent. To explore the grouting diffusion mechanisms of different grouting materials in frozen and thawed rock masses, a true triaxial stress-state frozen and thawed rock mass fracture grouting experiment was conducted. Computed tomography (CT) and scanning electron microscopy (SEM) were performed on the grouted specimens to obtain the grouting diffusion patterns and three-dimensional reconstruction of the grout veins in different frozen and thawed rock masses under fracture grouting. The results show that Portland cement slurry with low viscosity has better diffusion performance in unfrozen rock mass and rock mass after 10 freeze-thaw cycles. In the case of cement slurry containing graphene oxide and microsilica powder additives, the reinforced area exceeded that of ordinary cement after 10 freeze-thaw cycles, with the reinforced area reaching its maximum after 25 cycles. The “slurry-rock” interface primarily forms three modes: contact, embedding, and covering. Graphene oxide and microsilica effectively fill the larger pores in the cement particles, with microsilica being particularly effective in promoting cement hydration and reducing microdefects in the transition zone between the slurry and rock interfaces.

Features of the methods of the slope stability evaluation

Solving slope stability problems and selecting optimal calculation methods remains an urgent problem. A significant variety of engineering and geological conditions, and a large number of factors that can affect the stability of the slope, lead to the need to select a calculation method in each specific case.
 The article examines the features of the two most common methods of calculating the stability of slopes and slopes in geotechnical practice. The first group - limit equilibrium methods, has been widely tested and is the basis of simple engineering calculations of slope stability. Within the framework of the article, the circular cylindrical sliding surface method based on the method of moments, the method of horizontal forces, the methods of tangential forces based on the analytical method of H.M. Shakhunyanets, with the introduction of calculation schemes and the mathematical apparatus of these methods, are considered. The method of L. P. Yasyunas was also noted due to the idea he highlighted of simplifying calculations using unit shear pressure, which is generally an interesting idea but has certain difficulties in practical implementation. The key advantages and disadvantages of the finite element method for solving slope stability problems are given. The question of combining MSE with the method of reducing strength to determine the coefficient of stability of slopes is highlighted.
 Several software complexes are presented that allow us to automatically determine the coefficient of stability of slopes based on different groups of methods. A comparative calculation of the imaginary slope of PC "Plaxis 2D" and "Ukis" was performed. Two formulations of the problem are considered: for a free slope and with an additional load in the upper part of the slope. The received coefficients of stability and the shape of the sliding surface were analyzed and a generalized table of results was formed. The displayed results demonstrate sufficient convergence, which confirms the possibility of using the specified methods in engineering practice to determine the stability coefficient of slopes.

Reliability analysis of slope stability by neural network, principal component analysis, and transfer learning techniques

The prediction of slope stability is considered as one of the critical concerns in geotechnical engineering. Conventional stochastic analysis with spatially variable slopes is time-consuming and highly computation-demanding. To assess the slope stability problems with a more desirable computational effort, many machine learning (ML) algorithms have been proposed. However, most ML-based techniques require that the training data must be in the same feature space and have the same distribution, and the model may need to be rebuilt when the spatial distribution changes. This paper presents a new ML-based algorithm, which combines the principal component analysis (PCA)-based neural network (NN) and transfer learning (TL) techniques (i.e. PCA–NN–TL) to conduct the stability analysis of slopes with different spatial distributions. The Monte Carlo coupled with finite element simulation is first conducted for data acquisition considering the spatial variability of cohesive strength or friction angle of soils from eight slopes with the same geometry. The PCA method is incorporated into the neural network algorithm (i.e. PCA-NN) to increase the computational efficiency by reducing the input variables. It is found that the PCA-NN algorithm performs well in improving the prediction of slope stability for a given slope in terms of the computational accuracy and computational effort when compared with the other two algorithms (i.e. NN and decision trees, DT). Furthermore, the PCA–NN–TL algorithm shows great potential in assessing the stability of slope even with fewer training data.

A Comprehensive Numerical Modeling Study for Parameter Optimization and Slope Stability Analysis in the Baganuur Lignite Coal Mine

The “Baganuur” lignite coal mine is one of the biggest open cast mines in Mongolia. However, there is a huge challenge in managing the stability of its internal dump, which prevents the proper operation of the mine and has an impact on the economy. To solve the internal dump slope stability problem, this study focused on incorporating the inherent mechanical properties of the rock material to build numerical models of the internal dump. By applying two software programs from Rocscience (Phase2 and Slide) and four different methods, the finite element method, the Bishop method, the Janbu simplified method, and the Spencer simplified method, the current and improved internal dump parameters were numerically simulated and analyzed. Based on the properties of the rock, the LEM and FEM were used to determine the parameters that could have an impact on the stability of the internal waste dump. The impacts of the internal dump height, dip angle, and safety berm on these parameters were studied. This study covers several analytical methods for calculating safety factors. Based on the results of the numerical simulation, it is determined that it is possible to increase the internal dump capacity by approximately 56% at a 50 m height and 28° dip angle and using a 15 m safety berm. Under similar conditions, this study presents an optimum SRF at 40 m height, 28° dip angle, and 5 m safety berm. Based on the numerical models, it is found that changes in the dip angle have a greater impact than changes in the dump height on the slope stability of an internal dump.

Comparative analysis of 2D and 3D slope stability problems using limit equilibrium technique-based Bishop’s simplified method

Comparative analysis of 2D and 3D slope stability problems using limit equilibrium technique-based Bishop’s simplified method

Slope stability analysis considering fully saturated poro-elasto-plasticity by an image-based scaled boundary finite element approach

Open pit mines are large geotechnical structures. Their stability is an important consideration in the mining industry. The deformations of geotechnical structures often involve the coupled interaction between the pore fluid pressure and the nonlinear deformation of soil, characterised by poro-elasto-plastic behaviour. This paper develops the scaled boundary finite element method (SBFEM) to address poro-elasto-plastic in slope stability problems. It builds upon a previously developed elasto-plastic formulation to consider the effect of pore fluid pressure and its interaction with the nonlinear deformation within the soil. The pore pressure field introduces an additional variable in the governing equations that is similarly discretised using SBFEM shape functions. The SBFEM is implemented together with a pixel-based quadtree mesh generation technique, enabling automatic meshing directly from digital images. This leads to efficient automation when modelling problems with iterative changes in the geometry such as in optimisation of construction processes during the rehabilitation of slopes. The formulation is validated first using a standard numerical benchmark. Application of the developed technique in construction applications in slopes where the stability and effect of pore water pressure is considered e.g., tailings dam construction and optimisation of backfilling process is demonstrated in three examples to demonstrate feasibility.

Prediction of stability coefficient of open-pit mine slope based on artificial intelligence deep learning algorithm

The mining of open pit mines is widespread in China, and there are many cases of landslide accidents. Therefore, the problem of slope stability is highlighted. The stability of the slope is a factor that directly affects the mining efficiency and the safety of the entire mining process. According to the statistics, there is a 15 percent chance of finding landslide risk in China’s large-scale mines. And due to the expansion of the mining scale of the enterprise, the problem of slope stability has become increasingly obvious, which has become a major subject in the study of open-pit mine engineering. In order to better predict the slope stability coefficient, this study takes a mine in China as a case to deeply discuss the accuracy of different algorithms in the stability calculation, and then uses a deep learning algorithm to study the stability under rainfall conditions. The change of the coefficient and the change of the stability coefficient before and after the slope treatment are experimentally studied with the displacement of the monitoring point. The result shows that the safety coefficient calculated by the algorithm in this paper is about 7% lower than that of the traditional algorithm. In the slope stability analysis before treatment, the safety factor calculated by the algorithm in this paper is 1.086, and the algorithm in this paper is closer to reality. In the stability analysis of the slope after treatment, the safety factor calculated by the algorithm in this paper is 1.227, and the stability factor meets the requirements of the specification. It also shows that the deep learning algorithm effectively improves the efficiency of the slope stability factor prediction and improves security during project development.

A perturbation method for upper bound analysis of stability of slopes based on rigid translational/rotational moving elements

Collapse mechanisms consisting of translational or rotational rigid blocks are widely used as the basis for computing the upper bound on the factor of safety in slope stability problems. Constructing admissible velocities for these blocks mechanism often relies on experience, and optimizing these blocks can be cumbersome work, especially for layered slopes containing both hard and soft layers. In this paper, we present a numerical technique for evaluating and optimizing mechanisms composed of an arbitrary number of spline rigid translational/rotational moving elements, assuming plane strain material obeys the Mohr-Coulomb yield condition. In the proposed method, coordinates defining the nodes of the blocks are treated as unknowns, and the optimal geometry is found by successively perturbing node coordinates and block velocities, starting initially from a user-specified structured mesh. Two different definitions of the factor of safety are considered and the corresponding analysis procedures are introduced. The proposed method is applied to four examples related to slope stability analysis, and these examples illustrate that the proposed method is an efficient and reasonable way to analyze the stability of slopes.