Rock Slope Failures Research Articles

Mechanical interpretation of retrogressive failure in mild dip rock slopes induced by slope cutting and rainfall: a case study in Yunnan, China

Mechanical interpretation of retrogressive failure in mild dip rock slopes induced by slope cutting and rainfall: a case study in Yunnan, China

Engineering geological characterization and assessment of complex rock slope failures in Mudurnu, Turkey

Engineering geological characterization and assessment of complex rock slope failures in Mudurnu, Turkey

Comprehensive analysis of multiple machine learning techniques for rock slope failure prediction

In this study, twelve machine learning (ML) techniques are used to accurately estimate the safety factor of rock slopes (SFRS). The dataset used for developing these models consists of 344 rock slopes from various open-pit mines around Iran, evenly distributed between the training (80%) and testing (20%) datasets. The models are evaluated for accuracy using Janbu's limit equilibrium method (LEM) and commercial tool GeoStudio methods. Statistical assessment metrics show that the random forest model is the most accurate in estimating the SFRS (MSE = 0.0182, R2 = 0.8319) and shows high agreement with the results from the LEM method. The results from the long-short-term memory (LSTM) model are the least accurate (MSE = 0.037, R2 = 0.6618) of all the models tested. However, only the null space support vector regression (NuSVR) model performs accurately compared to the practice mode by altering the value of one parameter while maintaining the other parameters constant. It is suggested that this model would be the best one to use to calculate the SFRS. A graphical user interface for the proposed models is developed to further assist in the calculation of the SFRS for engineering difficulties. In this study, we attempt to bridge the gap between modern slope stability evaluation techniques and more conventional analysis methods.

Peridynamic modeling of step-path failure in rock slopes

This work is devoted to investigating the step-path failure of rock slopes using peridynamic theory. To this end, an extended bond-based peridynamic model that can explicitly distinguish between tensile and shear cracks from mixed-mode fracture phenomena, previously proposed by the authors, is first introduced. Then, the fracture processes of gypsum specimens with various triple-flaw distributions under uniaxial compression are simulated at a laboratory scale. Tensile, shear, and mixed tensile-shear failure modes are reproduced, and the feasibility of the numerical tool is verified via comparison with experimental observations. Finally, the progressive failure of rock slopes at the field scale is analyzed, in which crack initiation, propagation, coalescence, and eventual structural damage are well captured. The types of crack propagation and coalescence predicted in this study contribute to understanding step-path failure mechanisms in experimental research and nature.

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.

Mechanical analysis of toppling failure using FDEM: A case study for soft-hard interbedded anti-dip rock slope

In recent years, massive interbedded sandstone and slate anti-dip slopes have been discovered in the southwest and northwest regions of China. The distinct mechanical properties of different rock layers make these slopes particularly unique. In this paper, the finite-discrete element method (FDEM) is used to study the toppling failure mechanism of soft-hard interbedded anti-dip rock slopes (SHIADRSs). Firstly, the numerical model of soft-hard interbedded anti-dip rock slope (SHIADRS) is established based on a centrifugal loading test. Then, the stress state, evolution of displacement and cracks, and progress of toppling failure in the SHIADRS are analyzed. Besides, the effect of rock structure, slope angle, dip angle, and rock mechanical properties on the toppling failure of SHIADRS is discussed. The simulation results show that the toppling failure process of SHIADRS can be divided into three stages. The stress distribution in hard rock (HR) is obviously different from that in soft rock (SR) layers. HR layers bear greater bending moments than HR layer during the toppling failure of the soft-hard interbedded anti-dip rock slopes. In addition, the stability of SHIADRS is negatively correlated with the slope angle and the dip angle of rock layer. Compared to the inclination angle of rock layers, the slope angle has a more significant impact on the stability of slopes. The internal friction angle of the rock layer has almost no effect on the toppling failure of SHIADRS.

A Review of the Evolution Characteristics and Argillization of Clay Interbeds in Rockslides

Weak interlayers in rockslides often become the controlling factor for slope deformation due to their poor physical properties and tendency to undergo argillization. Achieving a comprehensive understanding of the weak interlayers will help us comprehend the mechanism of rock slope failure and protect people’s property. Some weak interlayers will develop into clay interbeds after tectonic activity and long-term groundwater action. A comprehensive review of clay interbeds includes a discussion on the formation conditions, the governing factors of the argillization process, and the investigation methods. The clay minerals in clay interbeds, illite, montmorillonite, and Kaolinite, play a major role in the acceleration of the argillization process. The argillization process can be observed through scanning technology and investigated using nonlinear dynamics, statistics, and numerical modeling methods, which may result in limitations for extracting parameters. It is necessary to conclude a unified evaluation standard to find the basic commonness during the argillization process of clay interbeds. It would be a future trend to establish the quantitative relationships among the mechanical strength, micro-structure and content of clay minerals of the clay interbeds during the argillization process.

Cosmogenic (10Be) surface-exposure ages from the Burtness Comb rock avalanche, Lake District, northwest England

The age of the lower component of the Burtness Comb rock avalanche debris tongue, Lake District, northwest England, has been determined by in situ produced terrestrial cosmogenic (10Be) surface-exposure dating of quartz veins from three boulders. Uncertainty-weighted mean ages of 17.37 ± 0.94 ka (determined using the Loch Lomond calibration dataset) and 16.08 ± 1.25 ka (determined using the CRONUS-Earth default calibration dataset) indicate that this component of the rock avalanche occurred during deglaciation following the local Last Glacial Maximum. The surface morphology displayed by the debris indicates it likely accumulated on glacier-free terrain, suggesting that the Burtness Comb cirque glacier had decoupled from the Buttermere valley glacier at the time of debris emplacement. The debris may have travelled across the surface of a waning glacier in the upper part of the cirque. Although the upper component of the rock avalanche is as yet undated its position and configuration indicate it to be younger than the lower component and sourced from a different part of the comb headwall. The rock avalanche is only the third of 84 rock slope failures recognised in the Lake District and adjacent Howgill Fells to have been dated using 10Be. Whilst the rock avalanche is regarded as a paraglacial landform, additional ages on other members of this population are required in order to establish their temporal pattern and to propose the most probable underlying cause(s) of 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.

Experimental study on the failure of fractured rock slopes with anti-dip and strong weathering characteristics under rainfall conditions

Experimental study on the failure of fractured rock slopes with anti-dip and strong weathering characteristics under rainfall conditions

Probabilistic Slope Stability Analysis of Mount St. Helens Using Scoops3D and a Hybrid Intelligence Paradigm

In the past, numerous stratovolcanoes worldwide witnessed catastrophic flank collapses. One of the greatest risks associated with stratovolcanoes is a massive rock failure. On 18 May 1980, we witnessed a rock slope failure due to a volcano eruption, and a 2185.60 m high rock slope of Mount St. Helens was collapsed. Thus, from the serviceability perspective, this work presents an effective computational technique to perform probabilistic analyses of Mount St. Helens situated in Washington, USA. Using the first-order second-moment method, probability theory and statistics were employed to map the uncertainties in rock parameters. Initially, Scoops3D was used to perform slope stability analysis followed by probabilistic evaluation using a hybrid computational model of artificial neural network (ANN) and firefly algorithm (FF), i.e., ANN-FF. The performance of the ANN-FF model was examined and compared with that of conventional ANN and other hybrid ANNs built using seven additional meta-heuristic algorithms. In the validation stage, the proposed ANN-FF model was the best-fitted hybrid model with R2 = 0.9996 and RMSE = 0.0042. Under seismic and non-seismic situations, the reliability index and the probability of failure were estimated. The suggested method allows for an effective assessment of the failure probability of Mount St. Helens under various earthquake circumstances. The developed MATLAB model is also attached as a supplementary material for future studies.

The role of progressive brittle fracture in the 1931 landslide at Dogface Rock, Katoomba

The 1931 Dogface Rock landslide in Katoomba NSW was a complex, progressive cliff collapse with a failure volume in the order of 100,000 m3 that was triggered by the extraction of remnant coal pillars from the Katoomba Colliery, about 200 m below the top of the escarpment. Although underground coal mining is generally accepted as a cause of the rockslide, previous studies have not explicitly investigated the role of progressive brittle fracture in the collapse. This paper presents an integrated study which incorporates remotely piloted aircraft photogrammetry with a discrete element method numerical investigation of the landslide, and thereby explores the role of progressive brittle fracture, and re-examines the failure mechanism and runout motion of this multi-stage landslide. Remotely piloted aircraft photography is used to build a georeferenced 3D model of the site with Structure-from-Motion photogrammetry software. A digital geotechnical mapping workflow is demonstrated to investigate the morphology of the landslide scar, extract statistics on discontinuity orientation, persistence, and spacing, and undertake trace mapping of newer brittle fractures that interacted with pre-existing high persistence joints as the landslide rupture surface developed. A series of discrete element method numerical laboratory tests are used to calibrate bonded block contact properties that reproduce laboratory scale intact rock index parameters including UCS and tensile strength. Upscaled rock block contact parameters are then applied to a cliff-scale model that investigates the progressive development of rock mass damage induced by mining. Following extraction of the remnant pillars, rock mass damage develops mostly by extensile strains that produce tension cracks. Brittle fractures propagate upwards from the mine level and eventually initiate toppling of massive sandstone slabs defined by high persistence pre-existing subvertical joints. The investigation illustrates how the integration of photogrammetry with discrete element numerical methods can be used to characterise progressive brittle failure and runout of large rock slope failures.

Polyphase rock slope failure controlled by pre-existing geological structures and rock bridges

Even after decades of intensive research, assessing rock slope stability remains a challenge. One reason for this is the spatial variability of rock bridges (RBs) related to non-persistent, pre-existing geological structures, especially as the detection of RBs is generally limited to the post-failure period. Thus, the identification and classification of RBs and their inclusion in numerical studies are demanding, yet essential, since even small quantities of RBs can be decisive for rock slope stability. In our study, we demonstrate how brittle RB failure and pre-existing geological structures control the mechanisms of a polyphase rock slope failure. Therefore, we present a case study in the Austrian Alps, where three rock falls with a failure volume of 30,000 m3 occurred in 2019. Based on detailed process reconstructions, high-resolution terrain models, and comprehensive geological and rock mechanical investigations, we derived high-quality input for our distinct element model (DEM). By applying asymmetric Voronoi tessellation in the DEM, we modelled the coalescence of pre-existing geological structures by brittle RB failure. As a result, we identified toppling as the predominant failure mechanism at the study site. Distinctive geological structures decisively affected the failure mechanism. However, the toppling failure was only reproducible by incorporating RBs in the DEM in their pre-failure position. Finally, we found that joint persistence, and consequently the presence of potential RBs, controls which initial rock fall failure mechanism was developed. In conclusion, we state that the initial toppling failure of the Hüttschlag rock falls is controlled by non-persistent geological structures in interplay with RBs.

Ice-buttressing-controlled rock slope failure on a cirque headwall, Lake District, UK

Abstract. Rock slope failures in the Lake District, UK, have been associated with deglacial processes after the Last Glacial Maximum, but the controls and timing of the failures remain poorly known. A cirque headwall failure was investigated to determine failure mechanisms and timing. The translated wedge of rock is thin and lies on a steep failure plane, yet the friable strata were not disrupted by downslope movement. Fault lines and a failure surface, defining the wedge, were used as input to a numerical model of rock wedge stability. Various failure scenarios indicated that the slope was unstable and would have failed catastrophically if not supported by glacial ice in the base of the cirque. The amount of ice required to buttress the slope is insubstantial, indicating likely failure during the thinning of the cirque glacier. We propose that, as the ice thinned, the wedge was lowered slowly down the cirque headwall, gradually exposing the failure plane. A cosmogenic 10Be surface exposure age of 18.0±1.2 ka from the outer surface of the wedge indicates Late Devensian de-icing of the backwall of the cirque, with a second exposure age from the upper portion of the failure plane yielding 12.0±0.8 ka. The 18.0±1.2 ka date is consistent with a small buttressing ice mass being present in the cirque at the time of regional deglaciation. The exposure age of 12.0±0.8 ka represents a minimum age, as the highly fractured surface of the failure plane has experienced post-failure mass-wasting. Considering the chronology, it appears unlikely that the cirque was reoccupied by a substantial ice mass during the Younger Dryas stadial.

An approach for prospective forecasting of rock slope failure time

Rock slope failures globally account for most single-event landslide disasters. Climatic changes in mountain areas boost failure activity and the demand for reliable failure time forecasts. State-of-the-art prediction models are often confused with high-frequency slope deformation data. Prospectively, they provide ambiguous forecasts as data filtering, starting point definition and forecast uncertainty remain arbitrary. Here, we develop a prospective failure time forecast model that applies multiple filtering and inverse velocity percentiles to minimize subjective decisions. We test the concept with 14 historic slope failures of 102-108 m3 including 46 displacement datasets from different sensors. After automatic detection of the onset of acceleration, the failure time of all events is forecasted to within −1 ± 17 h for higher-frequency data and −1 ± 4 d for daily data with a final mean uncertainty of 1 ± 1 d and 7 ± 4 d that is estimated in real-time. This prospective approach overcomes previous long-standing problems by introducing a robust and uniform concept across various types of catastrophic slope failures and sensors.

Rock slope failure preparation paced by total crack boundary length

Gravitational mass wasting prediction requires understanding of the factors controlling failure. Prior to slope failure, cracks in the weakened rock are thought to grow and coalesce, eventually forming a continuous failure plane. Here, we apply a hidden Markov machine learning model to seismic data, revealing the temporal evolution of cracks prior to a major rockslide event in the Swiss Alps. After prolonged linear increase of the crack cumulative number, an S-shaped crack rate pattern occurred in the day before the rockslide. A simple mechanistic model can explain this behaviour, showing that total crack boundary length is the key factor controlling failure plane evolution immediately before mass movement. Our findings imply that cracks should be treated as 2-D, rather than 1-D objects, and that slope failure can be driven predominantly by internal rather than external processes. Our model offers a novel, physically based approach for early warning of slope failures.

Reinforcement mechanism analysis of lattice beam and prestressed anchor rod system for loess slope

Lattice beam and prestressed anchor rod are used to enhance stability and prevent failure of soil or rock slopes. In this study, a model of Lattice beam and prestressed anchor rod (LBPAR) system was designed with reinforcement mechanisms and a model test was constructed with a circular slip surface of a loess slope. First, interaction between the loess slope and the LBPAR system was investigated by an LBPAR system analysis model. Stability of sliding mass from the sliding bed with an arc-shaped sliding surface was then studied by an experimental model designed. Finally, internal force distribution of lattice beams in the LBPAR system was investigated by using a large-scale physical model test. The results were compared to those calculated using the reverse beam method, indicating that the LBPAR system strengthened the sliding mass in space and improved the overall stability of the loess slope. With vertical loading, the axial tensile stress of the main anchor rod increases continuously. The bending area of the anchor rod was concentrated within 2 m of the sliding surface. And the maximum bending moment reaches 70 N·m. The sliding mass was subject to vertical load pressure, lattice beams’ pressure, and dead weight in the meantime and the maximum earth pressure value is near the node of the lattice beams. It is proved that such a method excels in the engineering design of loess landslides, which has promising applications in the future.

Probabilistic Analysis of Earthquake-induced Failure and Runout Behaviors of Rock Slopes with Discrete Fracture Network

Earthquake-induced rock slope failure is one of the most destructive geohazards, posing serious threats to human lives and properties. The potential hazard of a rock slope, under the loading of earthquakes, can be assessed from its failure and runout characteristics, which are however affected by inherent fractures. To simulate the randomness of these inherent fractures, the discrete fracture network (DFN) modeling technique that is based on the Monte Carlo simulation (MCS) is often employed. It is worthwhile noting that different realizations of DFN can be sampled from different MCSs; however, only one realization of DFN is considered and studied in the conventional analysis. There exist differences between the arbitrarily selected DFN and true DFN; as such, the conventional deterministic analysis could cause uncertainty in DFN modeling and the potential hazard of a rock slope cannot be accurately evaluated. In such a circumstance, this paper proposes a probabilistic analysis of earthquake-induced failure and runout behaviors of fractured rock slopes, in which multiple realizations of DFN that are systematically generated with MCS are taken as inputs to the discrete element method (DEM) modeling of slope behaviors, thus, the uncertainty induced by DFN modeling can be explicitly considered and evaluated.

Rock slope stability assessment using kinematic analysis at Gunung Batu, Lembang, West Java, Indonesia

Discontinuity plane in the Gunung Batu area associated with the geological structure of the activity of the Lembang fault has the potential to induce rock slope failure hazard to the surrounding residential areas. A series of slope stability analyses of the Gunung Batu was carried out using rock mass rating and kinematics analysis to assess the rock slope stability in the Gunung Batu and determine the rock failure type. According to the results of the rock mass rating, the outcrop of Gunung Batu is classified as a good rock. Meanwhile, kinematic analysis from three joint sets shows that the rock failure type is characterized by wedge and toppling failures. However, the analysis results of the Slope Mass Rating (SMR) indicate that the rock slope stability in Gunung Batu is considered in partially stable to stable condition.

Slope Stability Analysis Using Bishop Method and Slide 2D Software at Sand Stone Mining in Sedau Village, Narmada District, Lombok Barat Regency

Mining activities that involve constructing slopes will increase the potential for slope problems, especially those related to the increased potential for rock slope failure. Therefore, an in-depth study of the stability of the slope is required to determine the ability of the slope to stay stable without reinforcement or to choose the type of reinforcement that best fit a slope if it has a significant potential for landslides. This research aims to obtain the safety factor value of the sandstone mine slopes in Sedau Village, whether or not they comply with the safety requirements. Bishop’s method is employed to analyze the slip surface. Data processing is one of the requirements in Slide 2D Software to analyze slope stability based on material strength. The results of the safety factor obtained based on the analysis using the Bishop Method and 2D Slides are 1.671.