Rock Slope Instability Research Articles

Modeling the instability of rock slopes consisting of alternating weak and hard layers

Modeling the instability of rock slopes consisting of alternating weak and hard layers

Rock Slope Instability Mechanism Induced by Repeated Mining in Mountain Mining Areas

When mineral resources are extracted using underground mining methods in hilly regions, landslides or slope failures can be induced frequently. In this study, slope collapse disasters in mountain mining areas were analyzed. The model test and numerical simulation of the slope impacted by repeated mining were carried out. The crack evolution and failure process were analyzed to reveal the instability mechanism. The results show that the rock mass would topple to the inside of the slope first, when the subsidence of overlying rock was induced by the mining of the upper coal seam. When repeated mining was performed in the lower coal seam, the mining induced macro-cracks that could connect with natural fissures, inducing the outward displacement of the slope. Then, the rock mass at the foot of the slope has to bear the upper load, which is also squeezed out by the collapsed rock mass, forming the potential slip zone. Finally, the instability is caused by the shear slip of the slope toe rock mass. Therefore, the instability evolution of the slope under underground repeated mining disturbance can be divided into four stages as follows: roof caving and overlaying rock subsidence, joint rock toppling, fracture penetration, and slope toe shearing and slope slipping.

Effect of slope angle on fractured rock masses under combined influence of variable rainfall infiltration and excavation unloading

Intense precipitation infiltration and intricate excavation processes are crucial factors that impact the stability and security of towering and steep rock slopes within mining sites. The primary aim of this research was to investigate the progression of cumulative failure within a cracked rock formation, considering the combined effects of precipitation and excavation activities. The study was conducted in the Huangniuqian eastern mining area of the Dexing Copper Mine in Jiangxi Province, China. An engineering geological investigation was conducted, a physical model experiment was performed, numerical calculations and theoretical analysis were conducted using the matrix discrete element method (MatDEM), and the deformation characteristics and the effect of the slope angle of a fractured rock mass under different scenarios were examined. The failure and instability mechanisms of the fractured rock mass under three slope angle models were analyzed. The experimental results indicate that as the slope angle increases, the combined effect of rainfall infiltration and excavation unloading is reduced. A novel approach to simulating unsaturated seepage in a rock mass, based on the van Genuchten model (VGM), has been developed. Compared to the vertical displacement observed in a similar physical experiment, the average relative errors associated with the slope angles of 45°, 50°, and 55° were 2.094%, 1.916%, and 2.328%, respectively. Accordingly, the combined effect of rainfall and excavation was determined using the proposed method. Moreover, the accuracy of the numerical simulation was validated. The findings contribute to the seepage field in a meaningful way, offering insight that can inform and enhance existing methods and theories for research on the underlying mechanism of ultra-high and steep rock slope instability, which can inform the development of more effective risk management strategies.

How water, temperature, and seismicity control the preconditioning of massive rock slope failure (Hochvogel)

Abstract. The anticipation of massive rock slope failures is a key mitigation strategy in a changing climate and environment requiring a precise understanding of pre-failure process dynamics. Here we exploit >4 years of multi-method high-resolution monitoring data from a large rock slope instability close to failure. To quantify and understand the effect of possible drivers (water from rain and snowmelt, internal rock fracturing, and earthquakes), we correlate slope displacements with environmental data, local seismic recordings, and earthquake catalogues. During the snowmelt phase, displacements are controlled by meltwater infiltration with high correlation and a time lag of 4–9 d. During the snow-free summer, rainfall induces accelerations with a time lag of 1–16 h for up to several days without a minimum activation rain sum threshold. Rock fracturing, linked to temperature and freeze–thaw cycles, is predominantly near the surface and unrelated to displacement rates. A classic Newmark analysis of recent and historic earthquakes indicates a low potential for immediate triggering of a major failure at the case site, unless it is already very close to failure. Seismic topographic amplification of the peak ground velocity (PGV) at the summit ranges from a factor of 2–11 and is spatially heterogeneous, indicating a high criticality of the slope. The presented in-depth monitoring data analysis enables a comprehensive rockfall driver evaluation and indicates where future climatic changes, e.g. in precipitation intensity and frequency, may alter the preconditioning of major rock slope failures.

A novel proposed classification system for rock slope stability assessment

The present study introduces “rock slope instability score (RSIS)” a novel classification system for assessing rock slope stability. It takes into account geological and geotechnical parameters, as well as the impact of human activities and triggering parameters, which have become more frequent due to climate change and few of them have been ignored in existing classifications. The study focuses on rock slopes of various lithologies from the Indian Himalayas. The development of this new classification system is based on the examination of 81 different rock slopes from various states of the Indian Himalayas. Extensive field surveys, rock sampling, geotechnical laboratory tests, and ground measurements have been conducted at the various slope sites to establish a comprehensive scoring system for the stability assessment. The distributions of weightage to each parameter have been considered, corresponding to its degree of impact in causing slope instability. Sensitivity analysis of all defined parameters of RSIS system has revealed that the majority of the parameters exhibit a strong positive correlation, with Pearson correlation coefficients ranging from 0.74 to 0.61. However, two parameters, namely discontinuity dip and the relationship between slope & discontinuity direction, gives moderate relationship with correlation coefficient values of 0.48 and 0.41, respectively. To avoid any designer biasness in the system, several individuals gathered data set at different times. The proposed classification system has demonstrated a strong correlation with the actual slope condition, and it is quite promising. The outcome of RSIS classification for studied 81 slopes classified 2 slopes under stable condition, 21 slopes as partially stable, 44 as unstable, and 14 as completely unstable.

Energy evolution and strain localization in fractured sandstone under freeze-thaw cycling and uniaxial loading-unloading

In cold regions, combined cyclic freeze-thaw (F-T) and loading-unloading can cause rock slope instability and sliding. The macro-failure of rock masses originates from the expansion of strain localization areas driven by energy. Therefore, a deep understanding of the energy evolution and strain distribution can reveal the instability process. Along these lines, in this work, intact and intermittently jointed sandstones were subjected to a cyclic F-T environment and subsequently carried out uniaxial graded loading-unloading to obtain their mechanical parameters and X-ray computed tomography images. By investigating the energy density, it was found that the input, elastic, dissipated, and damage energies all increased with loading according to a quadratic polynomial function, with the energies obeying a linear allocation law. Meanwhile, F-T changed the energy storage capacity and energy dissipation coefficient of the rock by causing meso-damage. To measure the meso-scale strain localization characteristics, the advanced digital volume correlation technique was also used to obtain three-dimensional strain fields. In terms of local strain, the failure behavior of intact specimens under the application of low and high numbers of F-T cycles was controlled by potential fracture bands and frost-heave cracks, respectively, while fractured specimens were mainly dependent on the macro-fracture arrangement. However, both frost heaving and thawing transformed sandstone from brittle to ductile. In terms of statistical strain, the equivalent strain (εeq) showed a log-normal distribution and continued to deviate to the right due to loading-unloading. Meanwhile, the normal strain (εxx, εyy, εzz) exhibited a normal distribution, where fractured sandstone mainly developed along with the slip direction. Finally, the intrinsic correlations among the energy parameters, meso-damage, and macro-failure were discussed. From our analysis, three stages of energy allocation and transformation were revealed, namely the uniform allocation of damage energy, banded accumulation of damage energy, and fracture caused by the elastic energy release.

Assessment of discontinuity-controlled rock slope instability for debris slide initiation: a GIS-based kinematical analysis in the Great Smoky Mountains National Park, TN, USA

Assessment of discontinuity-controlled rock slope instability for debris slide initiation: a GIS-based kinematical analysis in the Great Smoky Mountains National Park, TN, USA

Data-driven early warning indicator for the overall stability of rock slopes: An example in hydropower engineering

In hydropower engineering, monitoring the instability of rock slopes is a crucial undertaking. Current early warning models of rock slopes lack consideration of the overall stability and cannot reflect the stability differences of different structure forms. Addressing these issues, we have successfully developed an integrative early warning indicator for the overall stability of rock slopes, utilizing the copula function and the safety stability rate. Initially, we introduce the safety stability rate to quantify the impact of rock structure on stability. Subsequently, the ISSR-MDF model, which integrates the safety stability rate with the marginal distribution function, is proposed. On this basis, we established the early warning indicator using the copula function. The results show that the indicator can reflect the structural characteristics of rock slopes and the trend of changes in multi-point residuals. The early warning model can provide valuable references for the stability assessment of slopes in hydropower engineering.

An integrated maximum safe slope angle analysis approach based on probabilistic kinematic and block theory for discontinuity-controlled rock slope instabilities: a transportation corridor case

An integrated maximum safe slope angle analysis approach based on probabilistic kinematic and block theory for discontinuity-controlled rock slope instabilities: a transportation corridor case

Assessing the Hazard of Deep-Seated Rock Slope Instability through the Description of Potential Failure Scenarios, Cross-Validated Using Several Remote Sensing and Monitoring Techniques

Foreseeing the failure of important unstable volumes is a major concern in the Alps, especially due to the presence of people and infrastructures in the valleys. The use of monitoring and remote sensing techniques is aimed at detecting potential instabilities and the combination of several techniques permits the cross-validation of the detected movements. Supplemented with field mapping and structural analysis, it is possible to define possible scenarios of rupture in terms of volume, mechanisms of failure and susceptibility. A combined observation strategy was applied to the study of major instability located in the Ticinese Alps (Switzerland), Cima del Simano, where the monitoring started in 2006 with the measurement of opened cracks with extensometers. Since 2021, the monitoring has been completed by LiDAR, satellite and GB-InSAR observations and structural analysis. Here, slow but constant movements of about 7 mm/yr were detected along with rockfall activities near the Simano summit. Eight failure scenarios of various sizes ranging from 2.3 × 105 m3 to 51 × 106 m3, various mechanisms (toppling, planar, wedge and circular sliding) and various occurrence probabilities were defined based on the topography and the monitoring results and by applying a Slope Local Base Level (SLBL) algorithm. Weather acquisition campaigns by means of thermologgers were also conducted to suggest possible causes that lead to the observed movements and to suggest the evolution of the instabilities with actual and future climate changes.

Coevolution of Rock Slope Instability Damage and Resonance Frequencies From Distinct‐Element Modeling

AbstractAmbient vibration measurements can detect resonance frequency changes related to rock slope instability damage or boundary condition changes during progressive failure. However, the impact of slope kinematics on resonance changes and the expected form and sensitivity of frequency evolution during destabilization require clarification to improve the implementation of this technique across diverse settings. Since instrumented rock slope failures are rare, numerical modeling is needed to study the anticipated spectral response from in situ monitoring. We used 2D distinct‐element modeling to evaluate the sensitivity and evolution of rock slope resonance behavior for slab toppling, flexural toppling, and planar sliding instabilities during progressive failure. Model simulations revealed that fundamental resonance frequency decreases between 20% and 60% with changes correlated with increasing length of open joints. Changes to higher‐order frequencies associated with landslide sub‐volumes were also detectable for cases with multiple fracture networks. Resonance behavior was most pronounced for failures dominated by steeply dipping open tension cracks, that is, flexural and slab toppling. Additionally, amplification patterns across the slope varied for the flexural toppling and sliding cases, providing potential new information with which to characterize landslide failure mechanisms using ambient vibration array measurements. Our results demonstrate landslide characteristics well‐suited for in situ ambient resonance monitoring and provide new data describing the anticipated changes in resonance frequencies during progressive rock slope failure.

Experimental study on instability mechanism and critical intensity of rainfall of high-steep rock slopes under unsaturated conditions

Two critical factors, namely intense precipitation and intricate excavation, can trigger rock mass disasters in mining operations. In this study, an indoor rainfall system was developed to precisely regulate the flow and intensity of precipitation. A large-scale model experiment was conducted on a self-designed physical simulation experiment platform to investigate the failure and instability of high-steep rock slopes under unsaturated conditions. The real-time reproduction of the progressive failure process in high-steep rock slopes enabled the determination of the critical rainfall intensity and revealed the mechanism underlying slope instability. Experiment results indicated that rainfall may be the primary factor contributing to rock mass instability, while continuous pillar mining exacerbates the extent of rock mass failure. The critical failure stage of high-steep rock slopes occurs at a rainfall intensity of 40 mm/h, whereas a rainfall exceeding 50 mm can induce critical instability and precipitation reaching up to 60 mm will result in slope failure. The improved region growing segmentation method (IRGSM) was subsequently employed for image recognition of rock mass deformation in underground mines. Herein an error comparison with the simple linear iterative cluster (SLIC) superpixel method and the original region growing segmentation method (ORGSM) showed that the average identification error in the X and Y directions by the method was reduced significantly (1.82% and 1.80% in IRGSM; 4.70% and 6.26% in SLIC; 9.45% and 12.40% in ORGSM). Ultimately, the relationship between rainfall intensity and failure probability was analyzed using the Monte Carlo method. Moreover, the stability assessment criteria of rock slope under unsaturated condition were quantitatively and accurately evaluated.

Fuzzy-Based Intelligent Model for Rapid Rock Slope Stability Analysis Using Qslope

Artificial intelligence (AI) applications have introduced transformative possibilities within geohazard analysis, particularly concerning the assessment of rock slope instabilities. This study delves into the amalgamation of AI and empirical techniques to attain highly precise outcomes in the evaluation of slope stability. Specifically, our primary objective is to propose innovative and efficient methods by investigating the integration of AI within the well-regarded Qslope system, renowned for its efficacy in analyzing rock slope stability. Given the complexities inherent in rock characteristics, particularly in coastal regions, the Qslope system necessitates adjustments and harmonization with other geomechanical methodologies. Uncertainties prevalent in rock engineering, compounded by water-related factors, warrant meticulous consideration during all calculations. To address these complexities, we present a novel approach through the infusion of fuzzy set theory into the Qslope classification, leveraging fuzziness to effectively quantify and accommodate uncertainties. Our approach employs a sophisticated fuzzy algorithm encompassing six inputs, three outputs, and 756 fuzzy rules, thereby enabling a robust assessment of rock slope stability in coastal regions. The implementation of this method capitalizes on the high-level programming language Python, enhancing computational efficiency. To validate the potency of our AI-based approach, we conducted preliminary tests on slope instabilities within coastal zones, indicating a promising initial direction. The results underwent thorough evaluation, affirming the precision and dependability of the proposed method. However, it is crucial to emphasize that this work represents a first attempt to apply AI to the evaluation of rock slope stability. Our findings underscore a high degree of concurrence and expeditious stability assessment, vital for timely and effective hazard mitigation. Nonetheless, we acknowledge that the reliability of this innovative method must be established through broader applications across diverse scenarios. The proposed AI-based approach’s effectiveness is validated through a preliminary survey on a slope instability case within a coastal region, and its potential merits must be substantiated through broader validation efforts.

Failure Mechanism of Anti-Dip Layered Soft Rock Slope under Rainfall and Excavation Conditions

The phenomenon of toppling deformation and failure is common in slopes with anti-dip structures, especially in soft metamorphic rock slopes. This paper aims to explore the instability mechanism of anti-dip layered soft metamorphic rock landslides. Taking the slope of a mining area in the southern Qinling Mountains of China as a geological prototype, a large-scale centrifuge model test and a numerical simulation based on the combined finite and discrete element method (FDEM) were performed. The deformation and failure process, failure mode, and failure path of the slope under rainfall and excavation conditions were simulated. The results show that both the physical centrifuge model test and the new numerical model test can simulate the instability process of anti-dip layered soft metamorphic rock slopes, and the phenomena simulated by the two methods are also very close. Rainfall mainly weakens the mechanical properties of rock, while the excavation at the slope toe mainly changes the stress field distribution and provides space for slope deformation, both of which accelerate the instability of the anti-dip soft metamorphic rock slope. The failure process of an anti-dip layered soft rock slope can be described as follows: bending of the rock layer–tensile fracture along the layer–flexural toppling and cracking perpendicular to the rock layer–extension and penetration of the tensile fracture surface–sliding and instability of the slope.

Experimental study on the reasonable proportions of rock-like materials for water-induced strength degradation in rock slope model test

Water-induced strength deterioration of rock mass is a crucial factor for rock slope instability. To better show the degradation process of rock slope water–rock interaction, we used bentonite as a water-sensitive regulator to build a new rock-like material that matches the features of water-induced strength degradation based on the cement-gypsum bonded materials. Twenty-five schemes of the material mixture proportion were designed using the orthogonal design method considering four factors with five variable levels, and a variety of experiments were conducted to obtain physico-mechanical parameters. In addition, one group of rock-like material proportion was selected and applied to the large-scale physical model test. The experiment results reveal that: (1) The failure mode of this rock-like material is highly similar to that of natural rock masses, and the physico-mechanical parameters vary over a wide range; (2) The bentonite content has a significant influence on the density, elastic modulus, and tensile strength of rock-like materials; (3) It is feasible to obtain the regression equation based on the linear regression analysis to determine the proportion of rock-like material; (4) Through application, the new rock-like material can effectively simulate or reveal the startup mechanism and instability characteristics of rock slopes under water-induced degradation. These studies can serve as a guide for the fabrication of rock-like material in the other model tests.

High Steep Rock Slope Instability Mechanism Induced by the Pillar Deterioration in the Mountain Mining Area

In hilly regions, landslides or slope failures are very common phenomena, when underground mineral resources are excavated. In this study, some landslide disasters in a mountain mining area were analyzed. The engineering geological and instability reason were investigated. The numerical simulation of a high steep rock slope disturbed by a room and pillar mine was established. The failure process of a high steep rock slope induced by the pillar deterioration was analyzed to reveal the characteristics of deformation and sliding. The results show that the pillar plays an important role in maintaining the stability of the slope, if the pillar can support the overlying rock mass, only a tiny deformation will be induced. When the pillar fails and the roof caves, the overlying rock mass above the room and pillar goaf will rapidly subside, and the crack evolution of slope is induced, forming the potential slip surface. The landslide mass gradually moves. When the rock mass at the middle and lower of the slope is squeezed out, slope sliding will be induced. The failure process can be divided into four stages as follow: tiny displacement is caused by the mining, roof collapse is caused by the pillar failure, the potential slip surface is formed from the crack evolution; the slope sliding is induced by the fracturing of rock mass at the middle and lower of the slope.

Long-Term Effect Analysis of a High Slope with Tunnel Structure Based on Three-Dimensional Mesh Reconstruction

The instability of high rock slopes with tunnel structures increases under the effects of earthquakes and rainfall. Limited studies have been conducted on the long-term effect analysis of high rock slopes with tunnels. Field electrical measurements on rock slopes have been conducted to study the response of high rock slopes with large cross-section tunnels during rainfall and seismic loading. The material threshold was determined using the resistivity probability density statistical method, and a three-dimensional geological visualization model was obtained. A three-dimensional mesh reconstruction method consisting of material segmentation, cluster filtering, mesh generation, and material attribute mapping modules was proposed. The three-dimensional model of high-cutting rock slope was reconstructed, and the three-dimensional finite element model of the rock slope with tunnel was obtained. The response analysis of the slope was performed during rainfall and seismic loading by employing the El-Centro wave. The results demonstrated that plastic strain was generated in the fracture zone of the upper part of the tunnel during rainfall, and the strain value was 8.135 × 10−4. In the subsequent stages, it had a tendency to expand into the tunnel under continuous rainfall. The maximum principal strain was 3.324 × 10−2 under the effect of a strong earthquake. A large strain was generated in the fracture zone at the upper part of the tunnel. It had a tendency to expand under long-term load, which significantly affected the safety of the tunnel.

Toward a Plausible Methodology to Assess Rock Slope Instabilities at a Regional Scale

Slope failures along road cuts and highways, occurring due to heavy rainfalls or earthquakes, pose significant threats to people, vehicles, and emergency plans. In the present study, a methodology to assess the stability of rock slopes at a regional scale is proposed using a kinematic analysis and a probabilistic limit equilibrium analysis for plane sliding and wedge failure modes. The workflow adopted is described through its implementation along the main road network of the island of Thasos, located in northern Greece. On-site investigations and measurements along the island’s road network formed the basis of the present study. The results of the kinematic analysis showed that the joint sets, which were identified during the on-site investigations, formed critical intersections that could lead to wedge and plane sliding failures. The on-site measurements and the results of the kinematic analysis were utilized to perform limit equilibrium back-analyses at sites of identified failures due to the water pressure effects to probabilistically estimate the material strength properties of the joints. Subsequently, numerous limit equilibrium analyses were executed within a Monte Carlo simulation framework to produce representative fragility curves of rock slopes against plane sliding and wedge failures along the main road network, due to earthquake loading and water pressures.

A Coupled Seepage–Deformation Model for Simulating the Effect of Fracture Seepage on Rock Slope Stability Using the Numerical Manifold Method

Modeling seepage problems in rock fractures is an interesting research approach to evaluating rock slope instability that is attracting increasing attention. In the present study, a coupled seepage–deformation model based on the numerical manifold method (NMM) is proposed, and the flow of groundwater in a fracture network coupled with the effects of seepage pressure and rock deformation are discussed. A global equilibrium equation of the system and a local factor of safety (FoS) of arbitrary rock fractures are derived based on the principle of minimum energy, and a series of verification examples are calculated. The simulation results show the robustness and effectiveness of the proposed numerical model. Finally, a rock slope collapse accident caused by seepage effects is simulated by the proposed method, and the failure process of the slope is reproduced. The simulation results show that excessive hydraulic pressure caused the vertical fractures to open and augmented the rock mass deformation, eventually leading to the failure of the slope. The proposed method possesses the potential to simulate larger-scale engineering problems.

Stability analysis of soft–hard-interbedded anti-inclined rock slope

The instability of rock slope is still a very frequent geological disaster, which seriously affects people's life and production activities. Previous studies have mainly focused on deformation mechanism, prediction, and control of hard rock with single lithology, while there are limited studies on the theoretic computational method of the stability for soft–hard interbedded anti-inclined rock strata. In this study, a geomechanical model for the toppling failure of soft–hard-interbedded anti-inclined rock slope is established. The modes of failure for soft and hard rock strata are analyzed, the computational formula of the downward thrust for each anti-inclined rock stratum is derived, and the stability safety factor of each rock stratum is defined. A theoretical computational method for determining the potentially most dangerous failure surface of soft–hard-interbedded anti-inclined rock slope is proposed. By comparing with the existing research results, the theoretical solving method proposed in this study can well solve the location of the potentially most dangerous failure surface of soft–hard-interbedded anti-inclined rock slope. The potentially most dangerous failure surface of this kind of slope is approximately planar, and the angle between it and the normal plane of the rock strata is an acute angle within 30°. It provides theoretical support for the stability analysis of this kind of slope.