Search

Στην παρούσα διπλωματική, διερευνάται η μορφολογική εξέλιξη ομοιόμορφων (c, φ) πρανών που υπόκεινται σε διαδοχικές αστοχίες. Η έρευνα διεξάγεται σε δύο μέρη: το αναλυτικό μέρος (με χρήση της μεθόδου οριακής ανάλυσης άνω ορίου) και το πειραματικό (με δοκιμές σε μοντέλα προσομοίωσης μικρής κλίμακας). Παρουσιάζεται ένα πειραματικό πρωτότυπο μοντέλο για τη μελέτη της επίδρασης της διείσδυσης νερού στη μορφολογική εξέλιξη των φυσικών πρανών που υπόκεινται σε διαδοχικές αστοχίες. Σχεδιάστηκε μια αλληλουχία εργαστηριακών δοκιμών μικρής κλίμακας για την προσομοίωση και διερεύνηση των διαδοχικών αστοχιών στο εργαστήριο. Οι αστοχίες επιτυγχάνονται μέσω μιας συσκευής που κατασκευάστηκε για να προσοιμοιάζει βροχόπτωση. Η υγρασία και η μύζηση του εδάφους κατά τη διάρκεια των δοκιμών παρακολουθόυνται από ειδικούς αισθητήρες που έχουν τοποθετηθει μέσα στο πρανές κατά την κατασκευή του μοντέλου. Επίσης, έχουν τοποθετηθεί κάμερες υψηλής ανάλυσης που καταγράφουν τη συμπεριφορά του μοντέλου του πρανούς και χρησιμοποιείται GeoPIV για την ανάλυση των φωτογραφιών ώστε να μετρηθούν οι μετακινήσεις και παραμορφώσεις κατά τη διάρκεια κάθε δοκιμής. Κατά τη δοκιμή και μετά από σύντομο χρονικό διάστημα βροχόπτωσης, εμφανίζονται κατακόρυφες ρωγμές στο μοντέλο, οι οποίες οδηγούν σε σημαντικές κατακόρυφες παραμορφώσεις μέχρι την πλήρη αστοχία. Τα πειραματικά αποτελέσματα δείχνουν ότι υπάρχει ισχυρή σύνδεση μεταξύ της περιεκτικότητας σε υγρασία και της εμφάνισης κατολίσθησης. Αναπτύσσεται ένα μοντέλο πρόβλεψης αστοχιών σε πρανή με βάση την παρατηρούμενη απόκριση των μοντέλων σε σχέση με την υγρασία του εδάφους. Στο αναλυτικό μέρος, παρουσιάζεται ένα ημιαναλυτικό μοντέλο για την εξέλιξη της μορφολογίας των πρανών με ή χωρίς ρωγμές. Αναπτύσσεται μια γενική αναλυτική λύση για το αξιολόγηση της ευστάθειας ομοιογενών πρανών που υπακούουν στο κριτήριο Mohr-Coulomb. Πραγματοποιείται παραμετρική ανάλυση για την αξιολόγηση της επίδρασης της μείωσης της αντοχής του εδαφικού υλικού με το χρόνο, της σεισμική δράση, του σχηματισμού ρωγμών και της ύπαρξης νερού στην εξέλιξη του πρανούς. Για την επίδραση του σεισμικού φορτιόυ γίνεται χρήση ψευδοστατικής προσέγγισης και για την επίδραση του νερού, ο συντελεστής πίεσης πόρων ru. Τέλος, παρουσιάζονται διαγράμματα ευστάθειας για τον υπολογισμό και πρόβλεψη αστοχιών σε πρανή για ένα εύρος τιμών γωνίας διατμητικής αντοχής (φ) μηχανικού ενδιαφέροντος.

This research was conducted in an area around AlemKetema, North Showa, central Ethiopia; with a general objective of conducting a rock slope stability assessment on the selected natural rock slope sections. To achieve this objective, slope stability probability classification was followed to determine the stability probability conditions of slope rock mass in the study area. These classification systems mainly depend on the primary data collected from field works. As a reason, systematic and extensive fieldwork was conducted. However, secondary data was also required to characterize the general conditions of the study area and to have a deep understanding of the subject matter. In the SSPC system, ratings for the degree of weathering, intact rock strength, method of excavation, roughness condition, and infill material were given according to standards. The slope stability probability classification (SSPC) system practices three-step classification systems. These steps are exposure rock mass, reference rock mass, and slope rock mass. Following these steps, slope rock mass stability probability classifications have been carried out for 92 natural rock slope sections. The stability of slope rock mass was determined by two different approaches namely orientation-dependent and orientation independent stability. Orientation dependent stability is linked with the orientation of the discontinuities and characterized by toppling and sliding criteria, while orientation independent stability is linked with the strength of slope rock mass. Accordingly, the overall assessment indicated that 80.4% of rock slope sections showed less than 5% stability probability, 10.9% of rock slope sections showed from 5 to 49%, 6.5% showed from 50 to 95%, and the rest 2.2% of rock slope sections showed greater than 95% stability probability. All these results were compared with the visual stability assessment results. Accordingly, different stability probability maps were produced.

The stability of high rock slopes has become a key engineering geological problem in the construction of important projects in mountainous areas. The original slope stability probability classification (SSPC) system, presented by Hack, has made obvious progress and been widely used in rock slope stability analysis. However, the selection and determination of some evaluation indexes in the original SSPC method are usually subjective, such as intact rock strength and weathering degree. In this study, the SSPC method based on geological data obtained in the prospecting tunnels was presented and applied. According to the field survey and exploration of the prospecting tunnels, the weathering degree of the slope rock mass was evaluated. The empirical equation for the maximum stable height of the slope was applied to the slope stability evaluation in the presented SSPC method. Then, the slope stability probability of numerous cutting slopes in the sandstone unit was evaluated using the presented system. Results of the Geostudio software based on the limited equilibrium analysis of the investigated slopes were compared with the results obtained by the SSPC method. The results indicate that the SSPC method is a useful tool for the stability prediction of high and steep rock slopes.

In stratified sedimentary and meta-sedimentary rock formations ‘plane mode’ of rock failure is very common. The plane failure occurs when a structural discontinuity plane such as; bedding plane, fault plane or preferred orientations of a joint set dips or daylight towards the valley or excavation at an angle smaller than the slope angle and greater than the angle of friction of the discontinuity surface. The stability of the slope, having plane mode of failure, depends on the geometry, rock type, potential failure plane characteristics, groundwater conditions, dynamic loading and the surcharge conditions. The slope may demonstrate these conditions in a simple uniform manner or there may be complex conditions owing to variability in the slope geometry and heterogeneity in the slope material. The stability of the slope, having plane mode of failure, can be assessed by different methods which can be broadly classified as conventional and numerical methods. Conventional methods include; kinematic methods, empirical methods, limit equilibrium and probabilistic methods, whereas numerical methods include continuum, discontinuum and hybrid methods. Each of these methods has their own advantage and limitations owing to the slope conditions, application requirement and capability of an expert. In this paper a comprehensive review on governing parameters and various stability analysis techniques for plane mode of failure in rock slopes is presented. Keywords: Rock slope stability, Plane failure, Limit equilibrium, Numerical methods

To investigate the strong random nature of the geometric interfaces between soil and rock, a rock-soil slope is considered as a two-phase random medium. A nonlinear translation of a Gaussian field is utilized to simulate the two-phase random media, such that the soil (or rock) volume fraction and the inclination of the soil layer can be examined. The finite element method with random media incorporated as the material properties is used to determine the factor of safety of the rock-soil slope. Monte-Carlo simulations are used to estimate the statistical characteristics of the factor of safety. The failure mode of the rock-soil slope is examined by observing the maximum principal plastic strain at incipient slope failure. It is found that the critical surface of a rock-soil slope is fairly irregular, and it significantly differs from that of a pure soil slope. The factor of safety is sensitive to the soil volume faction, but it is predictable. The average factor of safety could be well predicted by the weighted harmonic average between the strength of soil and rock; the prediction model is practical and simple. Parametric studies on the inclination of the soil layer demonstrate that the most instable scenario occurs when the slope angle is consistent with the inclination of the soil layer. Keywords: Slopes stability, Numerical computation, Statistical analysis, Finite-element modelling, Random fields, Monte-Carlo simulations

A three-dimensional numerical model was built incorporating stratigraphy, geological structures and mechanical properties of rock masses and discontinuities to perform stress, deformation and stability analyses for an excavated slope in China using the 3DEC software. Based on this model, numerical modeling was conducted to study the effect of boundary conditions, lateral stress ratio, and rock mass and fault parameter variability and uncertainty on the deformation and stability of the excavated rock slope. Displacement comparisons were made between the field monitoring values and numerical simulations. In the 3DEC modeling, both the stress and zero displacement boundary conditions were used to represent the lateral boundaries of the slope. Because the lateral boundaries were placed not far enough from the faults, the stress boundary conditions provided realistic results compared to the zero displacement boundary conditions. The best comparison with the field monitoring values were obtained when k0max is in the range 1–1.5 and k0min = 0.7. The best comparison between the numerical results and the monitoring data were obtained when the rock mass and fault property values were reduced by about 30% from the average material property values. The modeling approaches given in this paper should be useful in performing realistic three-dimensional stress, deformation and stability analysis of rock slopes.

Rock mass classifications are a simple yet useful tool to provide a practical assessment of rock slope stability. Among the available classifications for this purpose, Slope Mass Rating - SMR (Romana, 1985) is the most commonly used. It is based on the basic Rock Mass Rating - RMR (Bieniawski, 1989) and on adjustment factors related to the geometry and method of excavation of rock slopes. While SMR is a discrete method, the Slope Stability Probability Classification - SSPC (Hack et al., 2002), a less-known classification, is a probabilistic one. SMR gives better results when applied to structural-controlled rock masses, while SSPC provides solutions for both structural-controlled and nonstructural-controlled rock masses. The aim of this study was to assess the stability of cutting slope sections by SMR and SSPC along a BR-471 Highway segment, in Cangucu, state of Rio Grande do Sul, Brazil. The chosen area lies in the Pelotas Batholith, a 400 km-length unit, whose geometry and structures are regionally controlled by transcurrent shear zones. The location is characterized by a subtropical climate with high humidity and rainfall along the year. The analysis showed that the rock mass is structural-controlled, and many of the sections analyzed present stability problems. Comparing the methodologies applied, SMR indicates ten geotechnical zones as unstable or completely unstable, while SSPC indicates six unstable ones, which are all related to sliding failure, including both planar and wedge failures. Both methods applied showed good results. Yet, adjustments regarding the original criteria have real potential to improve further analyzes in the area. For SMR, the main suggestions include: adjustment of kinematic analysis weight in comparison to the weight of RMRb features, adjustment of weathering grade weight in relation to IRS, and inclusion of weight for large scale roughness. The suggestions for SSPC regarding structural-controlled stability are: adjustment of the susceptibility to weathering weight, focusing on the weathering of discontinuities, and the inclusion of the effect of water percolation.

A soil slope instability occurred at the surface facility area of a mine site, which was successfully managed from occupational health and safety point of view, and no human or material loss was encountered. Three different excavation stages and consecutively occurring slope failures were investigated by back analysis. Limit equilibrium and finite element methods were employed for back analysis. The multiple failures enabled researchers to verify the parameters investigated by back analysis to be obtained from each failure. Extensive field and laboratory testing were available which constitutes a baseline for comparison. The performance of tests and several correlations proposed by other researchers were compared to the back analysis findings. The correlations that used the advantage of plasticity index and depth were found to be superior compared to the other test methods for this study. Moisture sensitivity, high groundwater level, and sampling are found to be some of the main reasons leading to soil slope failure.

The stability of rock slopes is considered crucial to public safety in highways passing through rock cuts, as well as to personnel and equipment safety in open pit mines. Slope instability and failures occur due to many factors such as adverse slope geometries, geological discontinuities, weak or weathered slope materials as well as severe weather conditions. External loads like heavy precipitation and seismicity could play a significant role in slope failure. In this paper, several rock mass classification systems developed for rock slope stability assessment are evaluated against known rock slope conditions in a region of Saudi Arabia, where slopes located in rugged terrains with complex geometry serve as highway road cuts. Selected empirical methods have been applied to 22 rock cuts that are selected based on their failure mechanisms and slope materials. The stability conditions are identified, and the results of each rock slope classification system are compared. The paper also highlights the limitations of the empirical classification methods used in the study and proposes future research directions.

Geological uncertainty is often ignored in slope reliability analysis, even though the inherent variability of soil parameters is considered. This paper aims to propose a method for slope reliability analysis by considering both the inherent variability of soil parameters and geological uncertainty. A coupled Markov chain (CMC) model is used to simulate the geological uncertainty. An implementation procedure for slope reliability considering the aforementioned two types of uncertainty is provided. A slope reliability problem is analyzed to validate the proposed method with the borehole data from Perth, Australia. Different borehole layout schemes are designed to reflect the effect of both number and location of boreholes on slope reliability. Moreover, which type of uncertainty mentioned above has a greater impact on slope reliability is explored. The results indicate that the proposed method can effectively evaluate the slope reliability considering these two types of uncertainty. If only the inherent variability is considered, the accuracy of reliability analysis mainly depends on the used geological profiles. Borehole layout scheme has a significant effect on slope reliability. Both probability of failure ( P f ) and mean of factor of safety (FS) of slope do not monotonously vary with an increasing number of boreholes. The boreholes designed in the critical influence zone can provide more information to improve the accuracy of slope reliability. The coefficients of variation (COVs) of shear strength parameters and the discrepancy among the means of shear strengths for different soils play different and major role between the two types of uncertainty in the reliability analysis of soil slope.

Rock mass classification systems are commonly used to evaluate the likelihood of instability in mining environments. Most frequently used classification systems are the rock mass rating (RMR), geological strength index (GSI), and the Q-system. These methods are used widespread among geotechnical engineers as one practical way to assess quality of the rock mass. In most hard rock open pit mines, bench faces with no clear discontinuities present one or two joint sets that may dominate on the failure mechanism. To address this, slope mass rating (SMR), which is a modified version of the RMR system of rock mass classification, can be used. The benefit is that SMR takes into consideration the influence of joint orientation on the classification method itself. Hence, the main aim of this paper is: first, to develop a three-dimensional RMR model of an open pit mine under active operation based on the extensive field mapping carried out, and then produce an SMR surface model that is derived using current topography, modeled RMR values and jointing conditions prevailing in each structural domain. The final goal is to create an SMR susceptibility map of the mine area for the dominant topographic condition and the main structural domains present in the open pit, and to present a methodology that may be easily replicated at any given hard rock open pit mine. The authors emphasize that the use of an SMR model is a very helpful tool in evaluating the areas of the mine that are most vulnerable to potential slope instability in different periods of operation of the mine. This is a post-peer-review, pre-copyedit version of an article published in [Bulletin of Engineering Geology and the Environment]. The final authenticated version is available online at: https://doi.org/10.1007/s10064-017-1175-4

High-steep rock slopes are much more likely to collapse and form weir body due to earthquake. Converting the weir body to hydraulic engineering is a good way to deal with natural disasters. However, it is difficult to evaluate the stability of earthquake-induced rock slope due to the lack of shear strength parameters of rock mass. Based on three-dimension nonlinear finite elements, deformation reinforcement theory was adopted, in which plastic complementary is used to measure the global stability of slope, and unbalanced forces is utilized to identify the damage region. The shear strength parameters has been determined through back analysis based on stability and failure status before and after earthquake and monitoring data after earthquake. Then the stability evaluation under static conditions, dynamic conditions and rainfall conditions has been carried out respectively. The results show that failure mode of the slope under seismic load is consistent with the actual situation when the lowest material parameters are used. The major failure mode of the slope is sliding along the fault F5, and local collapse of the hanging body at the top of the slope under dynamic or rainfall load. The local stability can be improved effectively by excavating and taking bolt anchorages on the top of the slope.

When the slope is in critical limit equilibrium (LE) state, the strength parameters have different contribution to each other on maintaining slope stability. That is to say that the strength parameters are not simultaneously reduced. Hence, the LE stress method is established to analyze the slope stability by employing the double strengthreduction (DSR) technique in this work. For calculation model of slope stability under the DSR technique, the general nonlinear Mohr–Coulomb (M–C) criterion is used to describe the shear failure of slope. Meanwhile, the average and polar diameter methods via the DSR technique are both adopted to calculate the comprehensive factor of safety (FOS) of slope. To extend the application of the polar diameter method, the original method is improved in the proposed method. After comparison and analysis on some slope examples, the proposed method’s feasibility is verified. Thereafter, the stability charts of slope suitable for engineering application are drawn. Moreover, the studies show that: (1) the average method yields similar results as that of the polardiameter method; (2) compared with the traditional uniform strength-reduction (USR) technique, the slope stability obtained using the DSR technique tends to be more unsafe; and (3) for a slope in the critical LE state, the strength parameter φ, i.e., internal friction angle, has greater contribution on the slope stability than the strength parameters c, i.e., cohesion.

Q-slope is an empirical rock slope engineering method for assessing the stability of excavated rock slopes in the field. Intended for use in reinforcement-free road or railway cuttings or in opencast mines, Q-slope allows geotechnical engineers to make potential adjustments to slope angles as rock mass conditions become apparent during construction. Through case studies across Asia, Australia, Central America, and Europe, a simple correlation between Q-slope and long-term stable slopes was established. Q-slope is designed such that it suggests stable, maintenance-free bench-face slope angles of, for instance, 40°–45°, 60°–65°, and 80°–85° with respective Q-slope values of approximately 0.1, 1.0, and 10. Q-slope was developed by supplementing the Q-system which has been extensively used for characterizing rock exposures, drill-core, and tunnels under construction for the last 40 years. The Q′ parameters (RQD, J n, J a, and J r) remain unchanged in Q-slope. However, a new method for applying J r/J a ratios to both sides of potential wedges is used, with relative orientation weightings for each side. The term J w, which is now termed J wice, takes into account long-term exposure to various climatic and environmental conditions such as intense erosive rainfall and ice-wedging effects. Slope-relevant SRF categories for slope surface conditions, stress-strength ratios, and major discontinuities such as faults, weakness zones, or joint swarms have also been incorporated. This paper discusses the applicability of the Q-slope method to slopes ranging from less than 5 m to more than 250 m in height in both civil and mining engineering projects.

Stability analysis of rock slopes is a complex problem because of uncertainties involved in the rock mass properties. The probabilistic approach is a rational way to deal with these uncertainties. This article investigates the stability of a rock slope by deterministic and probabilistic approaches by considering uncertainty in peak and residual strength parameters and strength-drop in stress-strain behavior of the rock mass. A Geological Strength Index (GSI) based on a quantitative approach was used to estimate the statistical parameters of peak and residual strength parameters. Reliability index of the slope was then estimated using Hong's Point Estimate Method coupled with the finite element method. The approach is demonstrated using an important case study of a Himalayan rock slope supporting the piers of the world's highest railway bridge. It was observed that the factor of safety and reliability index for the slope was highly sensitive to residual strength parameters, and; hence, ignoring strength-drop from the rock mass behavior and uncertainty in residual strength parameters can overestimate the factor of safety and the reliability index of rock slopes. A parametric study is carried out to evaluate the influence of the coefficient of variation of uniaxial compressive strength of intact rock, the Hoek-Brown strength parameter of intact rock, roughness and alteration parameters of the joints on the probability of failure and the reliability index. The approach is verified by comparing the estimated displacements along the slope with in-situ measured displacements observed during field monitoring over the years. The approach used can be extended to the rock slopes or rock slides where high displacements in the slopes are expected due to triggering forces like seismic forces, excavation or structural loads.

The effects of slope surface material, slope gradient, block shape, and block mass conditions on rockfall rolling velocity were estimated with orthogonal test approach. Visual analysis shows that the importance of the factors is slope surface material > slope gradient > block shape > block mass. All the factors except block mass have the F value greater than the critical value, suggesting that these three factors are the key factors affecting the rockfall rolling velocity. Factor interaction analysis shows that the effect of the slope gradient relies largely on the slope surface conditions, and the block shape has little influence if the slope gradient is larger than a critical value. An empirical model considering the three key factors is proposed to estimate the rolling velocity, of which the error is limited to 5% of the testing value. This model is validated by 73 field tests, and the prediction shows excellent correlation with the site test. Thus, this analysis can be used as a tool in the rockfall behavior analysis.

The circular shear failure mechanism in rock slopes occurs in large-scale, heavily jointed or weak rock masses. Most rock slope stability analysis problems do not consider the effect of flow rules, i.e., the dilatancy angle. The failure criteria commonly applied are the linear Mohr-Coulomb or the non-linear Hoek and Brown. In general, all slope stability methods originate from the assumption of the associative flow rule, calculating equivalent values of the cohesive strength and friction angle. In this study, the non-linear Hoek and Brown failure criteria are applied in the parametric form, which permits the incorporation both the associative and non-associative flow rules. A theoretical approach of the limit equilibrium method is performed for circular slip surfaces under the assumption that there are only self-weight forces acting on the failure mass of the slope, taking the critical plane failure mode as the foundation. Both the analysis and results are performed in dimensionless form. The study emphasizes the importance of the value of dilatancy angle and “non-conservative” character of the hypothesis of the associative flow law, i.e., the overestimation of the value of the factor of safety. Specific examples are analysed and compared to the finite difference method and a real case is presented.

Quantitative risk assessment of slope failure is an important prerequisite for formulating rational strategies for landslide risk mitigation and developing a landslide risk-based warning system. Efficient risk assessment of slope failure in two-dimensional (2-D) spatially variable soils is a challenging problem. This paper proposes an efficient approach for quantitative risk assessment of slope failure considering the 2-D spatial variation of soil properties in the limit equilibrium analysis framework. To facilitate the risk assessment of slope failure, an empirical method is developed for the identification of slope key failure modes. With the proposed approach, the key failure modes of the spatially variable slope can be well identified and their contributions to the risk of slope failure can be effectively quantified. Finally, a two-layered soil slope is studied to illustrate the proposed approach. It is found that the prominent advantages of the proposed approach include being computationally efficient and accounting for the effect of the correlations among the failure modes.

The combined influence of nonlinearity and dilation on slope stability was evaluated using the upper-bound limit analysis theorem. The mechanism of slope collapse was analyzed by dividing it into arbitrary discrete soil blocks with the nonlinear Mohr–Coulomb failure criterion and nonassociated flow rule. The multipoint tangent (multi-tangent) technique was used to analyze the slope stability by linearizing the nonlinear failure criterion. A general expression for the slope safety factor was derived based on the virtual work principle and the strength reduction technique, and the global slope safety factor can be obtained by the optimization method of nonlinear sequential quadratic programming. The results show better agreement with previous research result when the nonlinear failure criterion reduces to a linear failure criterion or the non-associated flow rule reduces to an associated flow rule, which demonstrates the rationality of the presented method. Slope safety factors calculated by the multi-tangent inclined-slices technique were smaller than those obtained by the traditional single-tangent inclined-slices technique. The results show that the multi-tangent inclined-slices technique is a safe and effective method of slope stability limit analysis. The combined effect of nonlinearity and dilation on slope stability was analyzed, and the parameter analysis indicates that nonlinearity and dilation have significant influence on the result of slope stability analysis.

In contrast to the complex nature of slope failures, physically-based slope stability models rely on simplified representations of landslide geometry. Depending on the modelling approach, landslide geometry is reduced to a slope-parallel layer of infinite length and width (e.g., the infinite slope stability model), a concatenation of rigid bodies (e.g., Janbu’s model), or a 3D representation of the slope failure (e.g., Hovland’s model). In this paper, the applicability of four slope stability models is tested at four shallow landslide sites where information on soil material and landslide geometry is available. Soil samples were collected in the field for conducting respective laboratory tests. Landslide geometry was extracted from pre- and post-event digital terrain models derived from airborne laser scanning. Results for fully saturated conditions suggest that a more complex representation of landslide geometry leads to increasingly stable conditions as predicted by the respective models. Using the maximum landslide depth and the median slope angle of the sliding surfaces, the infinite slope stability model correctly predicts slope failures for all test sites. Applying a 2D model for the slope failures, only two test sites are predicted to fail while the two other remain stable. Based on 3D models, none of the slope failures are predicted correctly. The differing results may be explained by the stabilizing effects of cohesion in shallower parts of the landslides. These parts are better represented in models which include a more detailed landslide geometry. Hence, comparing the results of the applied models, the infinite slope stability model generally yields a lower factor of safety due to the overestimation of landslide depth and volume. This simple approach is considered feasible for computing a regional overview of slope stability. For the local scale, more detailed studies including comprehensive material sampling and testing as well as regolith depth measurements are necessary.

Slope stability assessment is a difficult geotechnical problem because of the many uncertainties involved. The uncertainties associated with soil parameters are significant, originating from limited and imprecise information, which allows for the soil parameters to be expressed as uncertain variables. The distributions of these uncertain variables are built on the basis of the structure of the soil layers of a slope, and the safety factor of slope stability is defined as a ratio of resisting and acting moments under uncertain environments. The expected value of the safety factor is therefore calculated by utilizing the operational laws of the uncertain variables. The concept of the reliability index of slope stability is also introduced in order to evaluate the risk of slope instability. Three numerical examples, including a homogeneous slope and two non-homogeneous slopes, are used to verify the proposed model; meanwhile, the results are compared with those of the Fellenius method. The numerical results indicate that the proposed model can not only improve the reliability of the calculated safety factor but also reduce the computational complexity compared to deterministic methods. Fifteen project instances taken from the literature are used to investigate the validity of reliability index, and the results illustrate that the reliability index is another useful indicator to assess the stability of a slope.

Root length, position and orientation on a soil slope are random but key elements when evaluating the stability of the vegetated slope. The main objectives of this note are to understand the effects of natural characteristics of vegetation on slope stability and to investigate how the variability in root features propagates to the variability in slope stability. A batch of randomly sized roots at given root densities are randomly positioned over a slope, and the stability of the slope for each combination of roots is evaluated. Traditional analysis considering uniform identical roots overestimates the factor of safety of the slope.

Correlated random variables are commonly involved in probabilistic slope stability analysis, such as reliability analysis of slopes with spatially variable soil properties. This paper proposes a simple Correlated Sampling Technique (CST) for generating samples of correlated random variables. The CST firstly produces correlated standard-normally distributed samples through linear combinations of independent standard-normally distributed samples. Correlated arbitrarily distributed samples can then be obtained by the Nataf transformation. The CST was combined with FOSM (named CST-based FOSM) for probabilistic slope stability analysis. The slope reliabilities of a single-layered cohesive soil slope and a high earth and rockfill dam were analyzed to illustrate the CST-based FOSM. These illustrative examples indicated that the CST-based FOSM can accurately estimate the slope reliability indices with considerably fewer simulations (especially in the case of low failure probability) compared with direct MCS, and the slope reliability was sensitive to the correlation of the strength parameters.

Catastrophic landslides maybe occur in rock slope due to the effect of strong earthquakes or heavy rainfall. The stability of rock slope is usually controlled by different scales of weak structural surfaces, which are uncertain and randomly exist in the rock slope. According to the geological characteristics of rock slope, two typical failure modes – plane and wedge are possible. A second-order second-moment (SOSM) method is presented to calculate the reliability index and the failure probability of rock slope, which is an improvement over the first-order second-moment (FOSM) method, and performance functions are built up with the classic limit equilibrium method. The presented method is applied to analyze the failure probability of two rock slopes at the Jinping I Hydropower Station and is compared with the Monte Carlo method and the FOSM method. The computed results show that for plane failure, the reliability index and the failure probability determined by the presented method are 0.563 and 28.7%, respectively, and the reliability index and the failure probability determined by Monte Carlo method are 0.677 and 24.9%, respectively. However, for the FOSM method, the reliability index and failure probability are –0.025 and 51.0%, respectively. For both plane failure and wedge failure, the difference between the presented method and the Monte Carlo method is very small, but the failure probability of plane failure determined by FOSM method is larger than that of the other two methods. The presented method can provide a useful tool to evaluate the failure probability of rock slope.

The investigation of mechanisms of multiple slope failure and the displacement of the resulting failure mass is highly important for the safety of the mountainous environments of the world. This study attempts to investigate such phenomena through numerical analysis. A one-dimensional (1D) surface flow and erosion/deposition model, a two-dimensional (2D) seepage flow model, a 2D slope stability model (the Spencer method of slope stability analysis), and a 1D sliding block model were combined as a single unit such that the developed model can also successfully analyze the surface water flow and erosion/deposition on the model slope soil surface, seepage-flow phenomena within the soil domain, and stability of the model slope during the movement of the sliding mass by updating the shape of the model slope according to the new position of the sliding mass. The Spencer method of slope stability analysis was incorporated into dynamic programming to predict the time of a slope failure and the shape of the failure surface. The data obtained from the numerical simulation results were compared with the experimental data obtained from Regmi et al. (2014) for validation. The application of the model in the real field would have significant impact for appropriate mitigation measures against probable disasters that may be caused by rainfall-induced landslides and slope failures.

Rock slope failure modes are either driven by structurally controlled mechanisms (planar, wedge, or toppling failure) or lean upon the highly jointed or weak rock mass (circular failure). Developing practical tools for preliminary slope design is a popular topic among geotechnical society. This study proposes a practical methodology to predict a safe overall slope angle for weak rock slopes of lignite mines. Rock mass rating (RMR) and slope mass rating (SMR) classification systems can be remarkably misleading for weak rocks. Fuzzy modification was proven to improve rock and slope quality predictions. In addition, structurally controlled failures can be estimated more precisely. Later, a popular slope performance chart of Bieniawski that is based on RMR was modified by the fuzzy approach, and the computer models of a weak rock mass failure in a Turkish lignite mine are presented. The modified methodology was proven to be better suited to the weak rock conditions.

A new computing method is proposed for reliable analysis. The limit state function is implicit and nonlinear in reliability analysis of slopes and is difficult to apply by traditional reliability methods, especially in large-scale project applications. Relevance vector machines (RVMs) are capable of approximating the limit state function without the need for additional assumptions regarding the function form, as opposed to traditional polynomial response surfaces. RVMs were adapted to obtain the limit state function. We propose an RVM-based response surface method combined with the first-order reliability method for slope reliability analysis and describe its step-by-step implementation. The reliability index obtained from the proposed method shows excellent agreement with traditional response surface method results. Copyright © 2017 John Wiley & Sons, Ltd.

The stabilization of slopes by placing piles is one of the most innovative and effective slope reinforcement techniques in the coastal engineering in recent years. Due to the simplicity and efficiency, limit analysis method is the most common approach for assessing the stability of slopes. However, the majority of existing limit analysis methods is limited to slope without the presence of piles. In this technical note, a novel upper-bound limit analysis method was proposed to access the stability of three-dimensional slopes reinforced with piles incorporating the admissible rotational failure mechanism where toe failure, face failure, and base failure were taken into account. The effects of key designing parameters, e.g., pile location, pile spacing, slope angle, slope width on the stability of earth slopes, and geometry of critical slip surface were presented and discussed. The results demonstrate that the proposed approach is more appropriate for assessing the stability of slopes reinforced with...

Based on the combination of FLAC3D software and strength reduction method, the applicability of three kinds of instability criterion of the stability of dip slopes with interbeddings of weak and hard rocks is studied. Then the failure process, failure mode and stability of the slopes are analyzed. The results show that: (1) the maximum unbalance rate affects the final calculated results; there is no certain relation between the convergence of calculation and the slope stability. The convergence of the displacement curves of key points and the ultimate displacement values should also be concerned to determine the slope stability. The maximum unbalance rate and the amplitude of the reduction affect the determination of the characteristic point in the displacement curve. It is difficult to quantitatively evaluate the shear strain rate when judging the slope stability, the judgment is not convenient and the error is large. Combining with calculation convergence criterion and feature point displacement mutation criterion is helpful to improve the accuracy of judgment on the limit state of the slope. (2) Slope deformation and failure process can be roughly divided into four stages qualitatively; the rock mass has buckling failure can be divided into three stages according to the deformation characteristics. The potential shear export of slope with buckling failure locates above the slope toe. Different combinations of weak and strong rock thickness does not affect the failure mode of slope, which all bellows to buckling failure mode, but it will affect the slope stability coefficient; with the increase of the thickness of strong rock and weak rock, the stability coefficient increases. If the thickness of the strong rock increases, the stability coefficient increases as well when the thickness ratio is constant.

How to efficiently assess the system reliability of rock slopes is still challenging. This is because when the probability of failure is low, a large number of deterministic slope stability analyses are required. Based on Subset simulation, this paper proposes an efficient approach for the system reliability analysis of rock slopes. The correlations among multiple potential failure modes are properly accounted for with the aid of the “max” and “min” functions. A benchmark rock slope and a real engineered rock slope with multiple correlated failure modes are used to demonstrate the effectiveness of the proposed approach.

Underground mining activities and rainfall have potential important influence on the initiation and reactivation of the slope deformations, especially on the steep rock slope. In this paper, using the discrete element method (UDEC), numerical simulation was carried out to investigate deformation features and the failure mechanism of the steep rock slope under mining activities and rainfall. A steep rock slope numerical model was created based on a case study at the Wulong area in Chongqing city, China. Mechanical parameters of the rock mass have been determined by situ measurements and laboratory measurements. A preliminary site monitoring system has been realized, aiming at getting structure movements and stresses of unstable rock masses at the most significant discontinuities. According to the numerical model calibrated based on the monitoring data, four types of operation conditions are designed to reveal the effect of mining excavation and extreme rainfall on the deformation of the steep rock slope.

Based on the unified strength theory, a new method to calculate the plane soil slope safety factor was derived that considers the effect of intermediate principal stressσ2and at-rest lateral pressure coefficientK0. Calculation examples from the literature were used to compare the new calculation method and the current slice method; the results showed that both provided good consistency. The new method can provide a reference for slope stability evaluation. The new method was used to calculate the soil slope safety factors for different values of intermediate principal stress parameterb, double shear stress parametersuτ′, and static lateral pressure coefficientK0. The results showed that the safety factorFsincreased whenbwas increased;Fsfirst increased and then decreased whenuτ′was increased; andFsincreased whenK0was increased. These results show that the intermediate principal stress as well as the stress state and its changes cannot be ignored during soil slope stability analysis. The slope soil characteristics and stress state should be considered to determine the unified strength theoretical parameters and static lateral pressure coefficient, maximize the potential of slope soil strength, and effectively reduce the costs of soil slope engineering.

In this paper, a system reliability analysis of rock slope stability with considering all input parameters as stochastic parameter is presented. To perform reliability analysis a cut-set system has been used. For this purpose, Sequential Compounding Method (SCM) as a powerful method for reducing the computational time and accurate evaluation is employed to determine the reliability indices with considering correlations between failure modes which are calculated by defining equivalent linear safety margin for each failure mode. Furthermore, the 3-D system probability of failure surface is presented and the probabilistic model is developed to evaluate the rock slope probability of failure.

Slope stability analysis in the middle part of the Mzymta-river valley was implemented. Several approaches were used to solve this problem. The first — traditional — is based on average value of the properties of soils. The second approach presents probabilistic slope stability analysis based on probabilistic distribution functions of the factors of landslide activity. It’s shown that the results of the probabilistic slope stability analysis agreed better with field observations. This type of analysis was added by sensitivity slope stability analysis, which is oriented on the dependence of the safety factor from the variability of parameters of landslide activity.

Two dimensional plain strain distinct element method has been used to analyze a curved slope under static and dynamic loading condition. Most vulnerable cross profile of the slope has been selected through kinematic analysis and slope mass rating specially devised for curved rock slopes. Static loading has been induced in the model to simulate conditions of the prevailing rock mass. Again dynamic loading has been performed according to the expected peak ground acceleration in the area in order to simulate the slope mass condition during earthquake. According to kinematic result and slope mass rating, the slope is more vulnerable towards 70° face direction. Static analysis results an unstable portion at the base of the slope. The whole slope is unstable under dynamic loading and is expected to threat the region with the risk of rock fall as well as failure of slope.

Slope failures associated with large-scale displacements and high strains in geomaterials have often resulted in large loss of life and properties in the Himalayan terrain. These slope failures bear a substantial relation to high-intensity rainfall events [1].One such slope is located at south portal of Rohtang tunnel, numerous slope failures due to the effect of fluctuating water table and rainfall events had already occurred. This paper describes variation in strength reduction factor (SRF) by a two-dimensional finite element based numerical modelling under four dominate strength reduction parameters. A total of one thirty-five analysis has been performed to obtain SRF values considering two sets of parameters. Three type of rocks constituting the slopes are Phyllitic quartzite, Quartzitic phyllite and Migmatite gneiss. Physico-mechanical behaviour of these rocks are investigated as per ISRM and BIS standards. The role of pore water pressure, joint inclination, slope angle and water table within the slope and its effect on failure is discussed in this paper.

This paper presents the case study of a stability analysis of an over-tilted (inverse) slope in an ornamental granite quarry. Based on traditional small quarrying practices and due to space constraints, the SW slope was carved following the occurrences of highly persistent joints that were dipping around 80° counter-slope. Experience dictates that this sort of slopes tends to be unstable, at least in case of average to low quality rock masses. In this way, a stability analysis was due to analyze slope stability. The good quality granite rock mass in the slope was characterized, joint data was recorded and laboratory testing was done to estimate the main significant parameters involved in the study and the geometry of the slope. A stability analysis of the slope was performed by means of the calculations of safety factors against toppling. These calculations have been done contemplating various possibilities regarding the occurrence of joints and its spacing, which was found to be the most relevant parameter controlling stability.

Based on the slope variation characteristics of slope break belt and slope theory in geomorphology, a method, which can quantitatively identify the slope break belt based on the precise seismic horizon data and slope gradient and aspect attribute, was established, and the mathematic surface model, dip logging, seismic attributes, and formation thickness contours were used to verify this method. Then, this method was used to quantitatively identify the distribution range and geometric parameters of the slope break belt in the Lower Cretaceous Qingshuihe Formation in Chepaizi area of Junggar Basin, NW China, the results show that the formation slope gradient calculated by this method is consistent with that reflected by the dip logging data, the distribution range of the slope break belt identified by this method is in line with the trend of the formation thickness and the distribution range of the discovered stratigraphic-lithologic reservoir, and the slope gradient attribute is better than formation dip attribute in identifying the slope break belt. The geometric parameters of the slope break belt which this method can identify are the accurate location of slope break and slope toe, the value of the slope gradient and the height difference and width between the slope break and slope toe. Key words: slope break belt, slope, seismic interpretation, Lower Cretaceous Qingshuihe Formation, Junggar Basin

With advances in technology increasing the economic depth limit of open-cut mines, including those in sedimentary strata, the design of stable slopes has become more critical. Increased use of geophysical logging to compliment more traditional geological and geotechnical logging provides an unprecedented detailed description of the rock mass from surface to sub-seam. Making full and best use of this data in a quantifiable, repeatable and transparent manner for the stability assessment of slopes requires a step beyond simplifying assumptions during limiting equilibrium and numerical stress analyses. By describing a repeatable deterministic model with parameterised input data we provide the basis for detailed probabilistic studies for the quantification of uncertainty. This paper considers the implication on slope stability, as measured by a Factor of Safety, of describing the strata at near geophysical log resolution. A comparison is made when representing the rock mass at increasing levels of detail with justifiable property estimates. We find that for deep pits in sedimentary rock masses a detailed description of the strata at near log resolution together with explicit representation of the near surface blast damaged zone becomes more critical as pit slope angle is optimised. This approach is demonstrated to capture the composite failure mode in sedimentary strata so that the predicted failure mode becomes a combination of low angle slip on weak units with high angle shear failure through stronger rock units as observed in the field. Compared to models with a simpler description of the rock mass, our model predicts that the mass of rock at failure becomes increasingly shallow and localised and is displaced near horizontally out of the pit slope, a failure mode observed in the field.

Discontinuity-controlled rock slope instability analysis is a difficult problem in the field of geotechnical engineering. Many random discontinuities existing in rock masses will negatively influence rock slope stabilities. This study is aimed to determine the failure angle (apparent angle of the sliding surface in the direction of the cut face) of potentially unstable blocks in discontinuity-controlled rock slopes in Dalian, China. For this purpose, a detailed discontinuity survey was conducted in seven exploratory trenches and two outcrops. Possible failure modes of the slope were predicted. Thus, according to theories of kinematics and probability statistics, it is possible to determine the failure angle of potentially unstable blocks with a new method that combines the results of Bayesian inference, probabilistic kinematic analysis and stereographic projection. Bayes’ formula was used to estimate the scientific value of the slope failure angle. A computer program called KINEMATIC was written to perform probabilistic kinematic analysis. Stereographic projection was used to verify the values obtained from the methods. Through the methodology proposed in the study, the failure angle of each excavation slope could be well calculated.

This study presents stability charts for estimating the stability of rock mass slopes that are suitable for the generalized Hoek-Brown (GHB) failure criterion based on the strength reduction technique. First, in order for implementing the GHB strength reduction, the estimation for the local Mohr-Coulomb (MC) friction angle and cohesive strength from the GHB criterion was incorporated into the strength reduction process in ABAQUS 6.10. Second, stability charts for calculating the FOS of rock slopes with a specific slope angle of β = 45° and D = 0 are proposed based on this method. Third, the disturbance weighting factors f D and slope angle weighting factor f β are used to quantify the effect of the rock mass disturbance factor and slope angle on the rock slope stability evaluations. Combined with the stability charts based on β = 45° and D = 0, the weighting factor f D and f β can be used to calculate the FOS of rock slopes with various slope angles under different blast damage and stress relief conditions. Finally, the stability charts were applied to two real case studies to illustrate the applicability and validity. The results for the two cases demonstrated good agreement with those from the other charts and the FEM software ABAQUS 6.10. The proposed charts provide a simple and straightforward way to estimate the FOS of the rock mass slopes directly from the GHB parameters.

Rock slope stability is of great concern along highway routes as stability problems on cut slopes may cause fatal events as well as loss of property. In rock slope engineering, stability evaluations are commonly performed by means of analytical or numerical analyses, principally considering the factor of safety concept. As a matter of fact, the probabilistic assessment of slope stability is progressively getting popularity due to difficulties in assigning the most appropriate values to design parameters in analytical or numerical methods. Additionally, the effect of heterogeneities in rock masses and discontinuities on the analysis results is minimized through the probabilistic concept. In this study, slope stability of high and steep sedimentary rock cut slopes along a state highway in Adilcevaz-Bitlis (Turkey) was evaluated on the basis of probabilistic approach using the Slope Stability Probability Classification (SSPC) system. The probabilistic assessment indicates major slope stability problems because of discontinuity controlled and discontinuity orientation independent mass movements. Almost all studied cut slopes suffer from orientation-independent stability problems with very low stability probabilities. Additionally, the probability of planar and toppling failures is significantly high with respect to the SSPC system. The stability problems along the investigated rock slopes were also verified by field reconnaissance. Remedial measures such as slope re-design and reinforcement at the studied locations should be taken to prevent hazardous events along the highway. On the other hand, the probabilistic approach may be a useful tool during rock slope engineering to overcome numerous uncertainties when probabilistic and analytic results are compared.

Because of the outstanding issue of high slope stability in hydropower project, the statistical slope stability analysis is studied by applying deformation monitoring data based on the probability and catastrophe theory. According to the analysis of geological conditions and measured information of high slope, the mechanical slope stability analysis is established. The EMD (empirical mode decomposition) method is introduced, which is used to fitting parameters and solving the aging component of slope deformation by breaking through the traditional regression model, and a method to abstract stationary and nonlinear aging component is proposed eventually. Combining with the theory of catastrophe, a cusp catastrophe model of slope stability is established. The early warning indexes of slope stability are put forward in terms of the deformation acceleration. Applying these above methods, the stability of the spillway high slope of a certain concrete face rockfill dam during operation period is analyzed and evaluated.

This paper aims to propose an auxiliary random finite element method (ARFEM) for efficient three-dimensional (3-D) slope reliability analysis and risk assessment considering spatial variability of soil properties. The ARFEM mainly consists of two steps: (1) preliminary analysis using a relatively coarse finite-element model and Subset Simulation, and (2) target analysis using a detailed finite-element model and response conditioning method. The 3-D spatial variability of soil properties is explicitly modeled using the expansion optimal linear estimation approach. A 3-D soil slope example is presented to demonstrate the validity of ARFEM. Finally, a sensitivity study is carried out to explore the effect of horizontal spatial variability. The results indicate that the proposed ARFEM not only provides reasonably accurate estimates of slope failure probability and risk, but also significantly reduces the computational effort at small probability levels. 3-D slope probabilistic analysis (including both 3-D slope stability analysis and 3-D spatial variability modeling) can reflect slope failure mechanism more realistically in terms of the shape, location and length of slip surface. Horizontal spatial variability can significantly influence the failure mode, reliability and risk of 3-D slopes, especially for long slopes with relatively strong horizontal spatial variability. These effects can be properly incorporated into 3-D slope reliability analysis and risk assessment using ARFEM.

Increases in rainfall and groundwater level rising can cause more frequent failures of unsaturated soil slopes, resulting in large-scale landslides. The aim of this paper is to propose a methodology for prediction of the failure of an infinite soil slope subject to steady unsaturated flow conditions. Probabilistic models for soil porosity, friction angle, matric suction and saturation are developed. The probability of slope failure for different groundwater levels and infiltration (or evaporation) intensities is investigated. Numerical results show that, for a slope with deep groundwater, the slope failure is mainly controlled by the rainfall infiltration, whereas for shallow groundwater, the slope failure is governed by the location of the groundwater level. A merit of the proposed methodology is that the fluctuation of the soil porosity along the depth of a slope is modelled as a Gaussian random field. The paper concludes that the proposed methodology can be used for prediction of slope failures under steady unsaturated flow conditions. Accurate prediction of slope failures can prevent catastrophic consequences of landslides.

The stability of a plane rock slope with cracks is evaluated based on the nonlinear Barton-Bandis (B-B) failure criterion and system reliability theory. The influence of different parameters and the crack shape on the reliability of a plane rock slope system was analyzed. The results showed that the residual sliding force can reveal the interaction between the two adjacent sliding bodies of a plane rock slope reasonably and intuitively. The Monte Carlo method provides an effective means to process a sampling simulation. The slope stability is greatly influenced by parameters including the underground water level, the residual friction angle of the rock surface ( ϕ r ), the joint roughness coefficient ( JRC ), and the joint compressive strength ( JCS ). With an increase in the uncertainty of the parameters, the value of the system reliability index falls significantly. An increase in the crack angle ( δ ), and a decrease in the horizontal distance B (the distance from the tensile crack to the edge of the slope top) causes the system reliability index to decrease rapidly, which indicates that the system reliability is highly sensitive to the crack shape.

Summary Because of a multitude of steep slopes being constructed adjacent to roadways, there is greater concern of landslide occurrence, particularly in instances where poor geomaterials are present. Installation of piles along the slope is one commonly adopted method. This paper presents the assessment of the stability of a rock slope with stabilizing piles based on kinematic analysis. The pile effect is introduced with a resultant lateral force and a moment. Upper bound solutions of the pile's lateral force are derived with a log-spiral rotational failure mechanism. The slope performance based on the bearing capacity of surcharge loading is also discussed with consideration of pore water pressure. In order to substantiate the derived theoretical solutions, numerical analysis with optimization technique is carried out. Results demonstrate that rock materials with high quality are conducive to ensure slope stability. Reduced lateral force on the pile is produced with lower rock weight, slope height, and surcharge loading. Finally, the safety factor and stability coefficient are discussed to complete the evaluation of the slope stability. Copyright © 2016 John Wiley & Sons, Ltd.

Precipitation frequently triggers shallow landslides in the Loess Plateau of Shaanxi, China, resulting in loss of life, damage to gas and oil routes, and destruction of transport infrastructure and farmland. To assess the possibility of shallow landslides at different precipitation levels, a method to draw slope units and steepest slope profiles based on ARCtools and a new method for calculating slope stability are proposed. The methods were implemented in a case study conducted in Yan’an, north-west China. High resolution DEM (Digital Elevation Model) images, soil parameters from in-situ laboratory measurements and maximum depths of precipitation infiltration were used as input parameters in the method. Next, DEM and reverse DEM were employed to map 2146 slope units in the study area, based on which the steepest profiles of the slope units were constructed. Combining analysis of the water content of loess, strength of the sliding surface, its response to precipitation and the infinite slope stability equation, a new equation to calculate infinite slope stability is proposed to assess shallow landslide stability. The slope unit stability was calculated using the equation at 10-, 20-, 50- and 100-year return periods of antecedent effective precipitation. The number of slope units experiencing failure increased in response to increasing effective antecedent rainfall. These results were validated based on the occurrence of landslides in recent decades. Finally, the applicability and limitations of the model are discussed.

To study the stability of the west slope in Buzhaoba Open-Pit Mine and determine the aging stability coefficient during slide mass development, the deformation band of the west slope and the slide mass structure of the 34,600 profile are obtained on the basis of hydrology, geology, and monitoring data. The residual thrust method is utilized to calculate the stability coefficients, which are 1.225 and 1.00 under sound and transfixion conditions, respectively. According to the rock damage and fragmentation and the principle of mechanical parameter degradation, the mechanical models of the slide mass development of the hard and soft rock slopes are established. An integrated model for calculating the slope stability coefficient is built considering water, vibration, and other external factors that pertain to the structural plane damage mechanism and the generating mechanism of the sliding mass. The change curve of the stability coefficient in the slide mass development is obtained from the relevant analyses, and afterwards, the stability control measures are proposed. The analysis results indicate that in the cracking stage of the hard rock, the slope stability coefficient decreases linearly with the increase in the length Lb of the hard rock crack zone. The linear slope is positively correlated to rock cohesion c. In the transfixion stage of the soft rock, the decrease speed of the stability coefficient is positively correlated to the residual strength of the soft rock. When the slope is stable, the stability coefficient is in a quadratic-linear relationship with the decreased height Δh of the side slope and in a linear relationship with anchoring force P. Keywords: Open-pit mine, Side slope, Sliding process, Aging stability, Crack zone