Search

Multiple researchers have effectively utilized InSAR for early identification research in southwest China. However, the intricate geological structure in this region includes deeply buried and unpredictable anti-dip stratiform rock slopes, posing an additional challenge for InSAR remote sensing. This study establishes a coupling relationship between slope topple deformation patterns and surface macro-deformation characteristics through a centrifuge model test, analyzing slope bending and topple deformation stages. The InSAR interpretation of prototype slopes is employed to retrospectively infer the slope stage and visualize the slope deformation process. This research provides technical assistance for identifying and preventing slope failures. The result demonstrates that: (1) The failure process of anti-dip stratiform rocky slope involves four major stages. Failures often begin at the slope's base and move to the middle and top regions, eventually resulting in entire slope failure when the stepped fracture surface forms. (2) Experimental image recognition analysis was conducted to monitor the rate changes in the deep and surface layers, establishing a corresponding coupling relationship between them. Observations reveal that significant deformation areas exhibit a bottom-to-top development pattern. (3) A comparison of the InSAR interpretation results for the Zhayong deformation with the test conclusions reveals that the landslide was in the progressive deformation stage. In summary, this study provides valuable technical support for utilizing InSAR technology to identify and prevent slope failures in complex geological conditions. [ABSTRACT FROM AUTHOR]

Wetting and drying cycles (WDCs) have a significant impact on the shear behavior of discontinuities with different joint wall materials (DDJMs). This influence is crucial for the reasonable evaluation of the long-term stability of soft and hard interbedded rock slopes under water level fluctuations. As the surface topographies of natural discontinuities collected from the field vary, conducting comparative experiments on natural discontinuity specimens with identical surface topographies is challenging. To solve this problem, a 3D surface topography reconstruction technique was employed to obtain DDJM specimens with three types of surface topographies collected from a typical sliding-prone stratum in the Three Gorges Reservoir area, China. A series of experiments, including computed tomography scanning, 3D laser scanning, and direct shear tests, were conducted to investigate the influence of WDCs on the micro- and macroproperties of joint walls, surface topographies, and shear behavior of DDJMs. The experimental results showed that repeated WDC treatments caused the degradation of the microstructures and macroscopic physical properties of the studied joint walls, and the more severely weakened joint wall played a predominant role in reducing the shear strength of DDJMs. The influence of WDCs on the surface topographies of DDJMs was negligible in this study; changes in the shear behavior of DDJMs were closely associated with the weakening of joint walls induced by WDCs; and the impact degree of joint wall weakening on the deterioration of the shear behavior of DDJMs was interactively influenced by and positively correlated with both the joint roughness coefficient and normal stress. These results will contribute to a better understanding of the evolution of the stability of soft and hard interbedded rock slopes induced by water level fluctuations in the Three Gorges Reservoir area and other reservoir regions. [ABSTRACT FROM AUTHOR]

The inherent spatial variability of rock mass strength has been explicitly considered in reliability analyses of slopes governed by the Hoek–Brown(HB) criterion. However, previous studies have primarily focused on extensive slopes where plane strain analysis is applicable, neglecting rock slopes constrained by boundaries that exhibit significant 'end effects' and are unsuitable for two-dimensional(2D) analysis. To bridge this gap, this research presents a novel three-dimensional(3D) reliability framework designed specifically for width-limited slopes in spatially variable rock masses. Considering the efficiency limitation of previously widely adopted numerical simulations, which struggle to accommodate extensive computation task, this study constructs the deterministic model using upper bound limit analysis (UBLA). A discretized mechanism is developed to determine the safety factor of spatially variable HB slopes. The integration of accelerated search strategies enables the determination of a solution to safety factor within a mere 5 min, mitigating the computational burden associated with high-dimensional stochastic problems or scenarios with a low probability of failure. Probabilistic analysis is conducted using a metamodel Sparse Polynomial Chaos Expansion (SPCE) in conjunction with Monte Carlo Simulation (MCS). Parametric analysis is employed to investigate the influence of various factors on slope reliability, including the autocorrelation length, coefficient of variation of strength, and correlation coefficient. This research presents a novel, computationally efficient deterministic model for slopes characterized by spatial variability in HB strength parameters. Furthermore, the employed principles show promising applicability in adjacent fields, such as tunneling and foundation engineering. Highlights: Develops a novel 3D reliability framework for width-limited slopes in spatially variable rock masses governed by the Hoek-Brown criterion. Develops an efficient UBLA-based deterministic model with a 3D spatial discretized technique and accelerated search strategies, reducing Fs computing time to within 5 mins. Integrates SPCE metamodel and MCS for probabilistic analysis, enabling investigation of various factors on slope reliability. The employed principles demonstrate promising applicability in adjacent fields, such as tunneling and foundation engineering. [ABSTRACT FROM AUTHOR]

Landslides resulting in complete river blockage have frequently occurred in the Three River Region (TRR) during the geomorphological evolution of the Tibetan Plateau. River-damming landslides occurring in low-relief regions of the TRR have received less attention compared to those in deeply-incised valleys. The 2.5 Mm3 Cuoduoqin rockslide originated from the south-facing hillslope of a southeast-east-trending ridge, leading to complete blockage of the Quzhaqu River. The original failure mainly involves blocky metamorphic limestone and phyllite. The Quzha Lake Fault providing rear rupture and two other groups of joints facilitating sidewise and toe releases are considered predisposing factors contributing to slope instability. Ongoing tectonic uplift and cyclic glaciations are considered preparatory factors, shifting the slope from stable to marginally unstable. A prehistoric earthquake, likely corresponding to an ancient rupture event on the active Nujiang Fault Zone (NJFZ), is deemed as the most probable trigger for this large rock slope failure. The 2D discrete element method (DEM) software UDEC is utilized to analyze the static slope stability and to reproduce the kinematic process of the rockslide. The static analysis indicates that the original rock slope was in equilibrium under natural conditions. The kinematic process can be divided into three phases: initial detachment within seconds after applying seismic load, downslope acceleration after crossing the slope knickpoint, and accumulation after traveling into the valley bottom. This case study, focusing on the development and kinematics of the Cuoduoqin rockslide, can help enhance the understanding of effective risk assessments of landslides in high-altitude and low-relief regions. [ABSTRACT FROM AUTHOR]

In evaluating the safety of rock slopes engineering, it is imperative to account for rheological effects. These effects can lead to significant deformations that may adversely impact the overall structural integrity. Consequently, accurate determination of the rheological mechanical parameters of slope rocks is essential. However, the application of rheological parameters obtained from laboratory tests encounters limitations due to the rock's inherent heterogeneity, scale effects, and inevitable sample dispersion. By contrast, on-site monitoring data serve as critical assets for real-time calibration and risk assessment in the evaluation of rheological parameters and prediction of slope deformation. To integrate on-site monitoring data with rheological mechanical mechanisms, this study introduces a probabilistic inverse model for evaluating rock slope rheological parameters, grounded in Bayesian theory, and incorporating a No-U-Turn Sampler (NUTS) based on Markov Chain Monte Carlo (MCMC) sampling algorithm. In terms of methodological efficiency, we compared the NUTS method with the traditional Metropolis–Hastings (M-H) approach, demonstrating the superior efficiency of the former. Additionally, sensitivity analysis of rheological parameters was conducted using the Burgers constitutive model. By combining the NUTS-based MCMC method with this model, the uncertainty of creep parameters was successfully evaluated. Utilizing these updated posterior parameters, up to 3-year deformation forecast for the slope was executed, the findings demonstrate that the deformation on the left bank slope is slight, indicating a state of safety. This study integrates monitoring data with rheological mechanics to establish a physical-data-driven rheological safety assessment mechanism. It offers a scientifically robust and effective approach for the uncertainty evaluation of rheological parameters and deformation prediction, providing significant support for the safety assessment of the left bank slope of the Baihetan hydropower station, China. [ABSTRACT FROM AUTHOR]

Understanding the dynamics of rock mass behavior necessitates the study of seismic waves generated by various sources of vibration within rocks. Joints and fractures are prevalent in rock masses and substantially impact their dynamic response to seismic waves. The present study has identified natural rubber latex (NRL) as an effective energy-absorbing medium in the rock masses for limiting wave propagation across the joint. Gypsum plaster has been used to replicate the natural rocks as a model material for conducting this study. The damping properties of rock mass have been determined using split shear plate (SSP) and resonant column (RC) tests. The mechanical response of intact gypsum plaster and NRL has been examined using resonant column testing. The influence of the thickness of the NRL layer on the damping characteristics of the jointed rock mass was studied by varying the thickness of the NRL layer within the joints from 2 to 5 mm. Using RC testing, the variations of shear moduli and damping ratios with different thicknesses of NRL have been studied. The variations of transmission coefficient (T), absorption coefficient (A), and reflection coefficient (R) with variable NRL thickness have been investigated utilizing SSP testing. The findings of the present study can be applied to developing numerical models that can anticipate the behavior of rock masses under dynamic loading conditions and for utilizing the NRL as an effective energy-absorbing material in the rock mass to reduce the vibrations that are transmitted to the structures. Practical Applications: The utilization of natural rubber latex (NRL) as an infill material in rock masses presents promising practical applications across various engineering domains. Its application extends to tunneling, mining, and stabilizing rock slopes. In tunneling and mining, NRL aids in increasing ground stability and controlling water intrusion during excavation, thereby enhancing safety and efficiency. In addition, it proves beneficial in stabilizing roofs and walls and preventing water and gas infiltration in mining operations. NRL reinforces joints within rock masses, reducing permeability and enhancing structural integrity. NRL stands out for its environmentally friendly and sustainable nature compared to synthetic polymers. Research indicates that NRL-stabilized soil has a lower carbon footprint than traditional cement-stabilized soil, thus offering an ecofriendly solution. Moreover, NRL presents opportunities for repurposing waste materials and reducing the environmental impact of concrete production. This study pioneers the application of NRL for vibration damping in jointed rocks, expanding the understanding of its dynamic properties under shear wave propagation. Through resonant column and split shear plate tests, this research explores the influence of NRL thickness on wave propagation, providing valuable insights for engineering practices in rock-dominated environments. [ABSTRACT FROM AUTHOR]

ABSTRACT The nonlocal general particle dynamics (NGPD) has been successfully developed to model crack propagation and large deformation problems. In this paper, the semi‐Lagrangian nonlocal general particle dynamics (SL‐NGPD) is proposed to solve brittle failure in rock slopes. In SL‐NGPD, the interaction between particles due to deformation is calculated in the initial configuration, while the friction contact interaction from discontinuities is calculated in the current configuration. The Van der Waals force model is utilized for friction contact. The bond‐level energy‐based failure criterion is developed to predict tensile/compressive‐shear mix‐mode cracks. The artificial viscosity and damage correction are used to enhance the numerical stability and accuracy when modeling brittle failure. The SL‐NGPD paradigm is numerically implemented through adaptive dynamic relaxation and predictor–corrector schemes for stable numerical solutions. The stability and accuracy of SL‐NGPD are verified by simulating compression tests. Thereafter, the crack coalescence patterns of double‐flaw specimens are investigated to understand the triggering failure mechanism of jointed rock slopes. Finally, the progressive failure process of the rock slope with step‐path joints is simulated to demonstrate its validity and robustness in modeling brittle failure in rockslides. The numerical results illustrate that the proposed SL‐NGPD is promising and performant for analyzing brittle failure problems in geotechnical engineering. [ABSTRACT FROM AUTHOR]

Vegetated concrete substrate (VCS) is a kind of ecological cemented soil, which has very wide application prospect in high and steep rock slope eco-protection. Cement is an important component of VCS, but it has high energy consumption and environmental pollution. Fiber reinforcement plays an positive role in improving the mechanical properties of soil, and its use as a substitute for cement content in VCS under the condition of equal strength is rarely investigated. In this study, the unconsolidated-undrained (UU) triaxial compression test of unreinforced substrate as blank control samples (BCS) and reinforced substrate as fiber reinforced samples (FRS) were carried out. The test results showed that the stress-strain curve of VCS can be divided into compaction stage, elastic stage, plastic stage and strain hardening stage. The average peak strength increased by 34.3kPa, 53.6kPa, 218kPa and 81.8kPa as cement content of VCS was 0%,4%, 6% and 8%, respectively. The relationship between the peak strength and cement content of VCS could be better fit by Boltzmann function. The mathematical model of fiber instead of cement in VCS under the condition of equal strength was established. It is found that there is a critical point of cement content according to the mathematical model. The cement of VCS can be completely replaced by plam fiber as the cement content is less than the critical point. While the cement content is higher than the critical point, the cement of VCS can be partially replaced by plam fiber. The decrease of average cement content was 17.23%, 19.00%, 24.27% and 25.34% with 0.2%, 0.4%, 0.6% and 0.8% fiber content in reinforced substrate, respectively. The theoretical method and interpolation method for fiber substitute cement content of VCS under equal strength condition were proposed, which can provide technical guidance for ecological slope protection engineering practice of vegetated concrete. [ABSTRACT FROM AUTHOR]

Uniaxial compressive strength (UCS) of rocks is one of the main parameters required in the design of geotechnical projects such as tunnels, dams, or rock slopes. According to the literature, there are a large number of predictive regression equations to evaluate the UCS from the point load index (PLI) and Brazilian tensile strength (BTS). However, the equations developed in previous studies have different accuracies in UCS prediction. A more accurate prediction of the UCS will result in a more appropriate design of the geotechnical project, and thus ensure its success during operation. In the present paper, a comparative study was conducted between the accuracy of PLI and BTS in predicting the UCS of the limestone and sandstone. Moreover, the role of porosity (n) on the accuracy of predicting the UCS from PLI and BTS was investigated. Some statistical indices were used to investigating the accuracy of predictive regression equations of UCS. The results revealed that the UCS of rocks can be predicted with a higher accuracy using BTS compared with PLI. Also, the findings showed that the n had a significant role in increasing the accuracy of PLI- and BTS-based regression equations of the UCS predictive. The predictive equations established in the present study can be used in practical applications for indirect evaluation of limestone and sandstone UCS in the site of a geotechnical project. [ABSTRACT FROM AUTHOR]

The propagation and coalescence of discontinuous cross-type joints are often the primary drivers of rock slope failures. Due to the inherent randomness of these joints, identifying suitable methods to accurately characterize progressive failure and quantitatively assess the stability of slopes with cross-type joints is particularly challenging. To address this, a Discrete Fracture Network-Spring Based-Smoothed Particle Hydrodynamics (DFN-SB-SPH) method is proposed, which considers cross-type DFN generation, rock matrix heterogeneity, cracking, block contact, and deposition within a unified SPH framework. In this approach, damage and contact of blocks are achieved by introducing a fracture sign to enhance the kernel function and applying Newton's law to the damaged particles to realize the point to point contact. A uniaxial compression test on rock samples with double fissures is carried out to verify the accuracy of the proposed method. The influence of joint density, geometric parameters (i.e., trace length, dominate dip angle) of cross joints, and rock mass heterogeneity on the failure characteristics of RSCD are investigated. The results revealed that the DFN-SB-SPH model possesses robust capabilities for crack tracking, mass movement, and contact slipping along fracture surfaces. Moreover, DFN generation, heterogeneous characterization, shear and tensile fractures within a single SPH framework without mesh distortion are realized. Five typical failure modes calculated by DFN-SB-SPH are primarily determined by the combination of joint dip angles and trace lengths. Furthermore, the dip angle, trace length, joint density, and rock mass heterogeneity significantly alter the stability of RSCD with sensitivity coefficients for factor safety of 27.7 %, 44.6 %, 72.9 % and 35.0 %, respectively. Higher dominant dip angles (above 60°) lead to significantly longer run-out distances for RSCD compared to lower angles (below 30°) once instability occurs. The sudden rise in major principal stress at the slope's top and toe, along with the shift of tensile stress concentration towards the middle, predicts the stages of crack propagation and sliding in slope failure. [ABSTRACT FROM AUTHOR]

The determination of the optimal random field element (RFE) size is crucial in soil slope reliability analysis as it governs the trade-off between precision in failure probability calculations and computational efficiency. Given the substantial computational burden associated with smaller RFE sizes, studies on their impact on slope failure probability are scarce. This research examines the influence of RFE size on failure probability and safety factor, employing the Karhunen–Loève expansion to generate random fields and integrating the simplified Bishop method with particle swarm optimization (PSO) to assess slope stability. Through Monte Carlo Simulation (MCS), this study investigates the effects of the ratio of slope height to RFE size (H/De) on slope reliability metrics across two illustrative cases. Results reveal a notable influence of H/De on the distribution of safety factors (Fs) and failure probability (PF), with overestimation observed at smaller H/De ratios. When H/De exceeds 10 for Example 1 and 15 for Example 2, the Fs distribution patterns in both scenarios stabilize significantly, displaying minimal variability. The PF of Example 1 and Example 2 decreases with the increase of H/De and remains basically unchanged when H/De exceeds 10 and 15, respectively. Consequently, a recommended H/De ratio of 20 is proposed based on the analyzed cases, facilitating accurate calculations while mitigating computational overhead. [ABSTRACT FROM AUTHOR]

The construction of the 275 m high Yusufeli arch dam and auxiliary structures required the execution of very steep cut slopes with more than 400 m height. Uncertainties regarding the geotechnical conditions imposed a serious challenge for the cut slope design. The design approach evolved from initial back‐calculations to a robust methodology, which was constantly revised and updated as excavation proceeded. The article explains the modular design procedure that allowed continuous interaction, adjustments and updates of and between different design and construction activities. It briefly describes the process of geological data collection and parameter determination and elaborates on the calculation tools utilised for the design. Finally, the verification and updating of the design during construction is explained on a selected case study. The excavation of the Yusufeli Dam was completed in 2018, dam concreting and grouting in 2022, and the final impounding level was reached by the end of 2023. [ABSTRACT FROM AUTHOR]

In the early hours of June 24, 2017, a major landslide event occurred in Xinmo Village, Sichuan Province, China. The landslide instantly devastated the whole village. Ten people died and 73 were missing in this major landslide event. The study area has suffered from several strong earthquakes in the past 100 y. Present studies have reported that the cumulative damage effect of the Xinmo landslide induced by earthquake is obvious. In this study, we conducted a shaking table test based on the detailed geological survey, historical seismic data, satellite optical image, unmanned aerial vehicle photography. The test result presents the characteristics of multistage seismic damage and progressive deformation process of the Xinmo landslide model, and shows that the historical earthquakes have caused serious damage to the interior of rock mass in the source area. The test also shows that the cumulative damage of the model increases with an increase in duration of earthquake loading. When the excitation intensity increases to a certain value, the damage accumulation velocity of the model suddenly increases. It reveals that frequent historical earthquake loads can be regarded as a main reason for the damage and deterioration of landslide rock mass. Damage accumulation and superposition occur in the slope. Under a long-term gravity, deformation of the slope gradually increases until catastrophic failure is triggered. The progressive deformation process of slope is summarized. Firstly, under strong earthquakes loading, a tensile fracture surface forms at the rear edge of the wavy deformation high and steep bedding slope. It reaches a certain critical depth and expands along the interlayer structural plane. Meantime, damaged fissures perpendicular to the structural plane also appear in the steep-gentle turning area of the slope. Secondly, under a coupling action of seismic loading and gravity, the interlaminar tensile crack surface at the rear edge of the slope extends to depth continuously. Meanwhile, rock fracture occurs in the steep-gentle turning area. The "two-way damage propagation" mode of the inter-layer tensile crack surface occurs until the sliding surface is connected. However, due to the "locking section" effect of rock mass at the slope foot, it can still maintain a short-term stability. Thirdly, under the influences of the heavy rainfall before a landslide and the long-term gravity of the upper sliding mass, rock mass in the steep section at the slope foot breaks outward. Finally, a catastrophic landslide occurs. [ABSTRACT FROM AUTHOR]

This paper proposes an improved discretization‐based kinematic approach (DKA) with an efficient and robust algorithm to investigate slope stability in nonuniform soils. In an effort to ensure rigorous upper‐bound solutions which may be not satisfied by the initial DKA based on a forward difference method (DKA‐FD), a central and backward difference "point‐to‐point" method (DKA‐CD and DKA‐BD) is proposed to generate discretized points to form a velocity discontinuity surface. Varying (including constant) soil frictional angles along depth are discussed, which can be readily considered in the improved DKA‐CD. Work rate calculations are performed to derive upper‐bound formulations of slope stability number, and critical failure surface is correspondingly obtained at limit state. The comparison with forward and backward difference methods clearly reveals that the improved DKA‐CD could significantly reduce the mesh‐dependency issue and enhance efficacy of slope stability analyses in nonuniform soils. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to propose a new combined finite-discrete element method (FDEM) to analyze the mechanical properties, failure behavior and slope stability of soil rock mixtures (SRM), in which the rocks within the SRM model have shape randomness, size randomness and spatial distribution randomness. Design/methodology/approach: Based on the modeling method of heterogeneous rocks, the SRM numerical model can be built and by adjusting the boundary between soil and rock, an SRM numerical model with any rock content can be obtained. The reliability and robustness of the new modeling method can be verified by uniaxial compression simulation. In addition, this paper investigates the effects of rock topology, rock content, slope height and slope inclination on the stability of SRM slopes. Findings: Investigations of the influences of rock content, slope height and slope inclination of SRM slopes showed that the slope height had little effect on the failure mode. The influences of rock content and slope inclination on the slope failure mode were significant. With increasing rock content and slope dip angle, SRM slopes gradually transitioned from a single shear failure mode to a multi-shear fracture failure mode, and shear fractures showed irregular and bifurcated characteristics in which the cut-off values of rock content and slope inclination were 20% and 80°, respectively. Originality/value: This paper proposed a new modeling method for SRMs based on FDEM, with rocks having random shapes, sizes and spatial distributions. [ABSTRACT FROM AUTHOR]

Digital photogrammetry technology has been extensively utilized in identifying rock mass discontinuities, with its measurement accuracy and multi-source errors have been thoroughly scrutinized. However, several challenges persist in field experiments, including the issue of inaccurately measured true data and errors in geo-referencing, which hinder the reliability of results. The purpose of this paper was to overcome the limitations of traditional field experiments through the digitized process in numerical simulation of photogrammetry, which has the advantages of high efficiency and high accuracy. Based on a case study of a rock slop, both field and simulation experiments were designed to quantitatively investigate the effect of coordinate accuracy of ground control points (GCPs) on the photogrammetric accuracy of discontinuity geometric parameters. The highly consistent results between numerical simulations and field experiments further confirmed the feasibility of the numerical simulation procedure. It is promising that the numerical simulation procedure has the potential to replace the field experiments by guiding and optimizing the arrangement scheme of camera stations and GCPs before fieldwork, thereby balancing efficiency and accuracy. Highlights: A novel idea combining field and numerical experiments of photogrammetry was proposed A case study was conducted to investigate the impact of GCP coordinate accuracy. Comparison between the two methods showed the reliability of the numerical simulation method. The accuracy and efficiency of digitized workflows highlighted the superiority of numerical simulation. [ABSTRACT FROM AUTHOR]

An improved method for fast and reasonable estimation of seismically induced permanent displacement of bedding rock slopes is proposed in this study. The proposed method introduces the pseudo-dynamic seismic force to account for the amplification effect induced by the slope topography. In addition, real-time updates of the tangential-normal coupling forces on the sliding surface during seismic excitations are implemented. The feasibility and adaptability of the proposed method are verified through a comparison with existing methods. Additionally, the differences between the earthquake-induced displacements calculated using the proposed method and the Newmark method are analyzed using 171 strong ground motion records as input excitations. A parametric sensitivity analysis shows that permanent displacement is significantly influenced by the friction angle of the joint ϕ , amplitude of the input acceleration P 0 , dip angle of the slope failure plane β , and slope height H . Finally, a set of landslide probability maps is obtained, and a landslide probability estimation procedure for slopes is recommended, which provides a convenient way to preliminarily evaluate the seismic stability of bedding rock slopes. Highlights: The amplification effect on the seismic response of rock slopes is considered. Tangential-normal forces on the sliding surface were coupled. Automatic recognition of sliding status is based on the Mohr–Coulomb criterion. Landslide probability maps are provided. [ABSTRACT FROM AUTHOR]

Stability assessment based on failure mechanisms is extremely crucial for slope quantitative evaluation. In this study, a vector sum particle flow method is proposed based on the mechanism of stepped tensile failure. This mechanism involves the mechanical behavior, lithology, and fracture properties. Furthermore, the proposed fracture criteria are reflected in the particle contact model of the 2D Particle Flow Code using a predefined strength envelope. Mesoscopic parameters are calibrated according to a certain strength parameter relationship, thereby realizing the construction of a vector sum numerical model. The failure evolution process of four slopes with different stepped crack arrangements is analyzed. Based on the analysis results, the stability analysis process of the slope is elaborated. This research analyzes the stability of the above four slopes and examines the stability of different failure stages during the formation of the sliding plane. The proposed method provides more accurate calculation results compared to the limit equilibrium method and gravity increase method. It accurately reflects the actual stress state of the sliding plane and indirectly considers the impact of the crack arrangement. The findings of this study are highly valuable for evaluating the stability of slopes experiencing stepped failure. [ABSTRACT FROM AUTHOR]

A massive toppling failure occurred at the edge of the Furnas Reservoir at 12:30 (UTC-03) on 8 January 2022, in Brazil. The toppling belongs to single-block toppling with a volume of about 3.32 × 102 m3 and caused 10 deaths and 32 injuries. Field investigation, numerical analysis, and base friction tests were performed to explore the failure characteristics and mechanism of the toppling. A conceptual model of the toppling mechanism was constructed and the toppling process was divided into four stages: foundation erosion and weakening stage, crack propagation and dislocation stage, opening up and rotation stage, and disintegration and collapse stage. A series of real three-dimensional numerical simulations was performed to clarify the toppling evolution and related triggering mechanism using the finite difference program FLAC3D. Two different alternatives of triggering mechanism for the toppling were comparatively analyzed, the first with a reduction in the shear strength of the weak foundation layer believed to represent the foundation weakening mechanism, and the second with removal of the weak layer believed to represent the foundation erosion mechanism. We found that the foundation weakening of the weak layer resulted in a sliding mechanism of the block, while the foundation erosion resulted in a clear toppling mechanism of the block. The base friction test was conducted to investigate the toppling process and to verify the numerical results over a limited time span. The experimental evidence demonstrated a good agreement with the numerical results as well as those observations in the field. We concluded that the slope was in a critical state due to the foundation erosion of the weak layer, while the heavy rainfall triggered the toppling. It is emphasized that the undermining of the slope foundation and/or existed cavities induced by the foundation erosion played a vital role in the formation of the toppling. Moreover, a produced vertical crack or the propagation of an existed crack in the rear part of the slope may be signs of movements and thought of precursors of the single-block toppling. Dealing with the eroded cavities was suggested to be an effective way to prevent the toppling in the Furnas Reservoir, such as backfilling the eroded cavities with masonry rubble and/or grouting. The understanding of the toppling characteristics and mechanism may offer a reference for single-block toppling issues, such as its movement characteristics and failure mechanism, and may be used for stability analysis and disaster identification of potential failures. [ABSTRACT FROM AUTHOR]

The ultimate bearing capacity of a strip footing placed horizontally over the edge of a sloping rock mass has been determined on the basis of the stress characteristics method (SCM) using the generalized Hoek–Brown yield criterion. The effect of footing–rock interface roughness on the results has also been analyzed. The problem has been solved, in addition, with the usage of the adaptive mesh–based finite-element limit analysis (FELA) method. The results are provided in the form of nondimensional bearing capacity factor (Nσ) as a function of different input material parameters for several slope inclinations. After analyzing all the results, an expression on the basis of the regression analysis has also been generated to compute the factor Nσ as a function of different input variables. The bearing capacity obtained from the SCM has been found to lie between the lower and upper bounds of the FELA, and the failure patterns from the two sets of analyses match quite closely with each other for both smooth and rough footings. The results are also found to be in good agreement with the existing solutions from the literature. [ABSTRACT FROM AUTHOR]

The construction of major hydropower projects globally is challenged by slope deformation in reservoir areas. The deformation and failure mechanisms of large rock slopes are complex and poorly understood, making prevention and management extremely challenging. In order to explore the influence mechanism of the water level variation on the deformation of steep toppling bedding rock slopes, this paper takes the right bank slope near the dam area of the Longtou Hydropower Station as an example, and field investigations, deformation monitoring, physical simulation tests and numerical analyses are carried out. It is found that the slope deformation response is obvious under the influence of the reservoir water level variation, which is mainly reflected in the change in the slope groundwater level, rock mechanical parameters and seepage field in the slope body. The toe of the slope produces plastic deformation and maximum displacement. With the increase in the reservoir water level, the plastic zone expands and the displacement increases, which leads to the intensification of the slope deformation. This paper puts forward that the deformation and failure modes of the steep and toppling bedding rock slope caused by water level variation are due to shear dislocation, bending deformation and toppling fracture. This study reveals the influence mechanism of the water level variation on the deformation of steep and toppling bedding rock slopes, which can provide theoretical support for the construction of major hydropower projects. [ABSTRACT FROM AUTHOR]

Ensuring the stability of slopes is critical to the safe operation of geotechnical engineering. Evaluating slope stability to minimize geologic risks induced by destabilization is significant in reducing casualties and property damage. A conventional, single-coefficient strength reduction method is widely applied in slope stability analyses, but this method ignores the attenuation degree of different parameters in the slope destabilization. A new double-strength reduction method considering different contributions of the mechanics' parameters is proposed in this study for evaluating the stability of nonhomogeneous slope. First, the role of each mechanic's parameters in the slope destabilization was investigated theoretically and numerically using ABAQUS software 2022. The results indicate that the effect of elasticity (E), Poisson's ratio (v), and soil gravity (γ) on the evolution of factor of safety (FOS) are insignificant and can be neglected compared with cohesive force (c), and angle of internal friction (φ). Next, an improved method was constructed to correlate the FOS with cohesive force (c) and the angle of internal friction (φ). Then, a numerical method was constructed based on the computation of the mathematical–mechanical relationship between FOS and the mechanical parameters, and the stability of slope is estimation based on the Mohr–Coulomb yield criterion. Finally, the double-strength reduction coefficient method proposed in this study, the limit equilibrium method, and the traditional finite element strength reduction coefficient method were applied to nonhomogeneous slopes and slopes containing a soft underlying layer for comparison, and the difference between them was within the range of ±5%. The results indicate that both the limit equilibrium method and the traditional finite element strength reduction method tend to overestimate the FOS of intricate slopes compared with the evaluated method proposed in this study. This parallel comparison serves to validate the accuracy of the double-strength reduction method proposed in the present study. Further, based on the proposed method, the relationship between slope stability and slope displacement is established, which provides a theoretical basis for the safety assessment of slope engineering. [ABSTRACT FROM AUTHOR]

AbstractPredicting landslide displacement is essential for developing early warning systems, assessing disaster risks, and understanding spatiotemporal evolution patterns. To address the limitations of insufficient accuracy in traditional landslide displacement prediction models, this study proposes a landslide displacement prediction model that combines an improved quantum genetic algorithm (IQGA) with a least squares support vector machine (LSSVM). The Mogu toppling rock slope is employed as a case study to demonstrate the application of the empirical mode decomposition (EMD) method for the decomposition of landslide displacement into trend and periodic components. Subsequently, these components are accurately predicted using Fourier series fitting and the IQGA-LSSVM model, respectively. The prediction results are subsequently evaluated and analyzed. The findings indicate that this model outperforms traditional QGA-LSSVM models, BP neural networks, and Support Vector Machine models in terms of prediction accuracy. Furthermore, the study illustrates how high-accuracy landslide displacement prediction models can effectively prevent and control disasters in critical areas such as hydraulic and hydropower engineering, urban planning, and geological disaster management. [ABSTRACT FROM AUTHOR]

Structurally controlled slope failure in open-pit mining occurs when the shear stress acting on the geological structure exceeds its shear strength. Mining slope stability is an extremely important topic from the ramifications of safety, social, economic, environmental and regulatory factors. This study reports the engineering geological setting of a bedded mining slope in China, and evaluates its stability via a numerical approach. First, a slope profile model is constructed using a synthetic rock mass (SRM) modeling approach. More specifically, the mechanical behavior of colluvium, intact rock and discontinuities are represented by linear contact model, bonded particle model and smooth joint model, respectively. Then, the factor of safety (FOS) and instability process are investigated by integrating the discrete fracture network (DFN)-distinct element method (DEM) and strength reduction technique (SRT). In addition, shear stress analyses of colluvium and bedrock are conducted for revealing the potential failure mechanism. Finally, the well-established limit equilibrium (LEM) and finite element method (FEM) are adopted for simulation results comparison and validation. [ABSTRACT FROM AUTHOR]

Toppling deformation can be classified into deep toppling (DT) and shallow toppling (ST) based on deformation mechanisms and development depth of rock mass under different soft and hard rock conditions. Currently, the toppling zoning indicators and quantitative criteria are not uniform, and human factors have a significant influence on the toppling zoning indicators. Summerizing and analyzing the existing toppling cases and toppling zoning researches, this study selects rock layer toppled angle, maximum tension within layer, unit tension within layer, and longitudinal wave velocity as indicators for toppling zoning. Considering the differences in the characteristics of deep toppling (DT) and shallow toppling (ST), the quantitative criteria for the deep and shallow toppling zoning indicators are determined respectively. This study employs the Analytic Hierarchy Process (AHP) and fuzzy comprehensive evaluation method to establish toppling zoning evaluation models. The deep toppling dam site slope at Miaowei hydropower station and the shallow toppling bank slope of Xingguang Π formation at Xiluodu Hydropower Station were tested, respectively. These results are compared with toppling zoning of field surveys to verify the rationality and applicability of the models. This achievement holds significant reference value for the toppling zoning of rock masses in engineering slopes, especially in the construction, development, and engineering management of toppling slopes. [ABSTRACT FROM AUTHOR]

Landslide is a disastrous geological hazard in the Three Gorges Reservoir (TGR) area of China. In this study, random limit equilibrium analysis is conducted to assess a layered slope stability influenced by multi-factors in spatially variable soils, where the effects of earthquake, reservoir water level drawdown and rainfall are investigated, and possible failure modes and failure paths are identified. Furthermore, some sensitive analysis is performed to investigate the effects of the spatial variability of soil properties, water level drawdown velocity, rainfall intensity and pattern. Results show that the layered slope under complex working conditions exhibits the shallow failure modes, and the sliding surfaces are mainly located at the interface between soil layers. Meanwhile, the shear strength parameters in the shallow depth plays a crucial role in the layered slope failure probability. The earthquake has a prominent effect on slope stability, followed by reservoir water level drawdown and rainfall infiltration. The probability of failure under the combined effects of earthquake and other factors (e.g., 23.5%, 31.4% and 44.6%) is significantly higher than under the combined effects of rainfall and water level drawdown (e.g., 15.9%). Moreover, it can be found that the spatial variability of soil properties, water level drawdown velocity, rainfall intensity and pattern have essential impacts on the slope failure probability. [ABSTRACT FROM AUTHOR]

Steep surrounding rock significantly challenges tunnel stability by affecting the stress distribution and deformation behavior. The angle of dip in surrounding rock greatly influences these factors, heightening the risk of instability along bedding planes, particularly under high ground stress conditions. This paper presents a comprehensive analysis of steep rock strata mechanical properties based on a railway tunnel in Yunnan Province, China. It incorporates long-term field monitoring and various laboratory tests, including point load, triaxial, and loose circle tests. Using experimental data, this study simulated the failure processes of steep surrounding rock and tunnel structures with a custom finite element method (FEM) integrated with the volume of fluid (VOF) approach. The analysis summarized the deformation patterns, investigated the causes of inverted arch deformation and failure, and proposed countermeasures. The findings reveal that increasing the rock dip angle results in greater deformation and accelerated failure rates, with the surrounding rock's loose zone stabilizing at approximately 8 m once deformation stabilizes. At a surface deformation of 8 cm, the failure zone extends to 6 m; however, this extension occurs more rapidly with higher lateral pressure coefficients. Additionally, failure zones develop more quickly in thin, soft rock on steep slopes compared to uniform rock formations. The rise of the tunnel floor is attributed to the steeply inclined, thin surrounding rock. To enhance bottom structure stiffness, this study recommends incorporating an inverted arch structure and increasing both the number and strength of the anchor bolts. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A quantitative interpretation of gravity anomalies in the Kalak-Bardarash area, west of Erbil City in the Kurdistan Region of Iraq, was performed using two-dimensional analysis techniques. These techniques modeled geological structures identified from a previously created Bouguer anomaly map of the area. Five profiles were selected for the analysis, resulting in eight models constructed for both deep and shallow-seated rock units. The deep-seated rocks are represented by the basement rocks, with models constructed in the NNE-SSW, WNW-ESE, and NW-SE directions using the regional anomaly component. The depth of the basement rocks ranges from five to nine kilometers and is affected by numerous faults in the form of graben and step structures. The basement rock surface slopes towards the NE and ESE at a gradient of 110 m/km. The shallow-seated rocks are represented by the sedimentary cover, which includes Neogene, Paleogene, and Cretaceous-aged groups of formations. The residual component of the anomalies of the five profiles were interpreted. Three profiles, oriented NNE-SSW and nearly perpendicular to the main anticlinal structure, revealed that the Bardarash anticline is influenced by two faults striking both limbs and extending in the NNW-SSE direction, with an estimated throw of 200 meters on each side. The southern fault is believed to extend down to the basement rocks. The other two profiles, oriented NW-SE and nearly perpendicular to the Zab River, indicated the presence of two additional faults with a throw of approximately 600 meters in the deeper parts striking the basement rocks, dipping towards the southeast. The throw of these faults gradually decreases upward in the sedimentary cover, reaching about 200 meters. These faults directly influence the course of the Zab River, directing it in a NE-SW direction at this district. [ABSTRACT FROM AUTHOR]

Slope failure is a severe disaster triggered by natural causes and human activity. To analyze the slope failure that occurred during the construction of Nanxia expressway, this study conducted on-site investigations and carried out tests at the exit of the deep excavation cutting section to reinforce the slope and improve its stability. The results reveal that the slope failure was triggered by excavation and heavy rain during the construction period. The initial design did not consider the specific geological conditions, and heavy precipitation increased the selfweight of the soil. In short, this accident was caused by natural causes and human activity. Using concrete to fill the landslide mass and extend the anchorage depth can enhance the slope stability. Alternatively, four grades of slope reinforcement and anti-slide pile reinforcement methods are also effective ways to reinforce bedding slopes with the same rock stratum inclination. Both design and construction problems can directly result in severe issues. To guide the construction more effectively, the designer should pay more attention to the geological conditions, instead of only focusing on the stability safety parameter. [ABSTRACT FROM AUTHOR]

Efficient and accurate extraction of discontinuity geometric parameters is significant for evaluating the stability and seepage characteristics of a rock mass. Traditional means of rock discontinuity measurement are susceptible to the influence of terrain and have issues such as high operational workload and low efficiency. An approach was proposed to comprehensively and efficiently obtain the geometric parameter information of the discontinuity, using an Unmanned Aerial Vehicle (UAV), which consists of the following five procedures: (1) measurement of a rock slope with UAV, (2) creation of three‐dimensional (3D) point cloud model for the slope, (3) voxel filtering of point cloud data, (4) planar segmentation based on modified region growing (MRG) algorithm, and (5) acquisition of parameter set of the discontinuity (orientation, trace length, and spacing). A new code, FacetDetect, has been developed based on this method to identify discontinuity from a 3D point cloud. Meanwhile, the trace length and spacing are calculated by the code written in Python. A comparison with the three‐point method reveals that most errors are less than 3° for dip angles and dip directions. These deviations are reasonable and confirm the reliability of the method. Overall, this method is a valuable reference for automatic discontinuity interpretation and related fields. [ABSTRACT FROM AUTHOR]

En-echelon joints are common in rocky slopes and faults, and their instability seriously threatens the safety of geotechnical engineering. Filling and reinforcing en-echelon joints in slopes is highly important for maintaining the safety of engineering and human beings. In view of this, this study aims to investigate the fracture behavior of en-echelon joints after filling and reinforcing to provide a reference for the filling and reinforcing work of slopes In this study, en-echelon gabbro samples with different crack angles were filled with cement slurry, a compression test was subsequently conducted, and the loading process was monitored via acoustic emission technology. The results showed that the compressive strength of the specimens after cementing the joints is increased by more than 30%, the compressive strength of the specimens with a β of 15°increased by up to 59%, and the stability of the specimens significantly improved. The shear failure of the filled and unfilled samples was the main failure at the peak load. There were two failure modes for the samples with different crack angles. The small dip angle samples were lightly broken, and the main cracks were distributed at the corner points of the samples. The large dip angle samples were broken considerably, and multiple fracture zones were present. Under pressure, the filled cement slurry weakened the stress concentration, and bore the compressive stress and shear stress, and the interface friction with the sample prevented the cracking and expansion of the crack, which resulted in a reinforcement effect on the sample. Our findings might act as a reference for the filling engineering of rock slopes with en-echelon joints. Highlights: Studying the effect of grouting reinforcement on the mechanical strength of rocks and fracture behavior is of great significance in engineering applications. The findings of this study might contribute to the field of filling defects and provide information that may help engineers with the filling and strengthening of rock slopes. In this study, the effects of filling cement on fracture behavior and strength of gabbro at different prefabricated joint angles were studied through compression tests, and the fracture mechanism of samples during loading was analyzed based on acoustic emission technology. Finally, the action mechanism of filling cement is explained. The filling cement slurry has remarkable reinforcement effect. Under the action of pressure, the filling cement slurry weakens the stress concentration, withstands the compressive stress and shear stress, and the interface friction with the sample prevents the crack cracking and expansion, which has a strengthening effect on the sample. [ABSTRACT FROM AUTHOR]

Highlights: The spatial distribution pattern, DSGSD characteristics and influence of the controlling factors of reservoir rock landslides were analyzed in Southwest China. The contribution of DSGSD to sliding deformation of a rock slope with landslide potential in the reservoir area was obtained. The mode of DSGSD evolution into landslides was summarized considering different combinations of bedding dip and slope angles. [ABSTRACT FROM AUTHOR]

The stability of gentle slopes is rarely accessed in existing studies, which are at risk of below-toe failure in soils with low shear strength. The inherent spatial variability of soil shear strength poses a huge complication to the probabilistic stability evaluation of large-scale three-dimensional gentle slopes, which usually forces a trade-off between precision and efficiency. In view of this, a semi-analytical method is developed in the framework of discretized limit analysis, which gives a unified mathematical representation of toe failure and below-toe failure of slopes. The proposed method inherits the high efficiency of analytical methods and has the ability to integrate spatially variable shear strengths into the slope mechanical model. The model validation is conducted by comparisons with a widely recognized analytical method developed for uniform soils. The random fields are introduced to achieve a relatively accurate characterization of soil shear strength, and the Monte Carlo simulation is employed to obtain a sufficient number of factors of safety of slopes for the subsequent statistical analyses. In the parametric study, spatial variability-related parameters, including the coefficient of variation of soil cohesion covc or internal friction angle covφ, the autocorrelation lengths along vertical and horizontal directions ξ and k, the cross-correlation coefficient ρcφ, are varied systematically to reveal their influences on the slope stability from a statistical perspective. It is found that the ranking of the impact on the probabilistic stability of a gentle slope is given as: covc or covφ > ξ > k > ρcφ. Finally, the failure probabilities of the gentle slope are computed considering the variations of key parameters, which may have implications for practical slope designs. [ABSTRACT FROM AUTHOR]

Unsaturated soil is widely distributed around the world but less considered in design due to the absence of a convenient analysis method in practice. The Morgenstern–Price (MP) method incorporating the extended Mohr–Coulomb shear strength equation provides a reliable approach to evaluate slope stability in such conditions. However, this method is time-consuming due to the need for a tedious trial-and-error process in determining the scaling factor, which involves complex iterations during each trial. Furthermore, since the relatively complicated nature of unsaturated soil, a dense slice division is necessary to obtain reliable results, making the analysis even more cumbersome. In this paper, an improved MP method for unsaturated soil slope stability analysis is presented, which eliminates the need for a dense slice mesh by employing only a few strategically placed Gauss points along the slip surface. Moreover, the trial-and-error process for determining the scaling factor with the corresponding complex iterations is replaced by an efficient search algorithm with a more concise iteration process, resulting in a more convenient implementation of the proposed method. Extensive examples are provided to validate the effectiveness of the proposed improved MP method, indicating its potential as an accurate and efficient analysis method for unsaturated soil slopes in practical application and relative study involving repetitive analyses. [ABSTRACT FROM AUTHOR]

The distribution and development of rock mass discontinuities in 3D space control the deformation and failure characteristics of the rock mass, which in turn affect the strength, permeability, and stability of rock masses. Therefore, it is essential to accurately and efficiently characterize these discontinuities. Light Detection and Ranging (LiDAR) now allows for fast and precise 3D data collection, which supports the creation of new methods for characterizing rock mass discontinuities. However, uneven density distribution and local surface undulations can limit the accuracy of discontinuity characterization. To address this, we propose a method for characterizing complex rock mass discontinuities based on laser point cloud data. This method is capable of processing datasets with varying densities and can reduce over-segmentation in non-planar areas. The suggested approach involves a five-stage process that includes: (1) adaptive resampling of point cloud data based on density comparison; (2) normal vector calculation using Principal Component Analysis (PCA); (3) identifying non-planar areas using a watershed-like algorithm, and determine the main discontinuity sets using Multi-threshold Mean Shift (MTMS); (4) identify single discontinuity clusters using Density-Based Spatial Clustering of Applications with Noise (DBSCAN); (5) fitting discontinuity planes with Random Sample Consensus (RANSAC) and determining discontinuity orientations using analytic geometry. This method was applied to three rock slope datasets and compared with previous research results and manual measurement results. The results indicate that this method can effectively reduce over-segmentation and the characterization results have high accuracy. [ABSTRACT FROM AUTHOR]

Rock avalanches onto glaciers are rare in Norway. Here, we examine a rock avalanche that spread onto the regenerated Brenndalsbreen, an outlet glacier from Jostedalsbreen ice cap. The rock avalanche is intriguing in that limited information exists with respect to the exact time of failure, location of detachment area, and preparatory and triggering processes. Based on an analysis of ice stratigraphy and photographic documentation, we assess that the event happened between mid-March and June 4, 2010. A potential triggering factor could have been heavy snow and rainfall combined with above freezing air temperatures on March 18–19, 2010. We use digital terrain models to determine that the detachment area is at an almost vertical rock slope in a narrow gorge above Lower Brenndalsbreen. The deposit volume is estimated to 0.130 ± 0.065 Mm3, and the H/L ratio and fahrböschung are 0.45 and 24°, respectively. We apply a Voellmy flow model to confirm the detachment location and volume estimate by producing realistic runout lengths. Although glacial debuttressing may have been a likely preparatory process, the detachment area was exposed for 45–70 years before the rock avalanche occurred. The supraglacial rock avalanche debris was separated into two branches with a distinct melt-out line across the glacier. The debris reached the glacier front in 2019 and 2020, where it started being deposited proglacially while Lower Brenndalsbreen kept receding. The 2010 Brenndalsbreen rock avalanche may not be a unique event, as deposits constituting evidence of an old rock avalanche are currently melting out at the glacier front. [ABSTRACT FROM AUTHOR]

Understanding the triggering factors leading to rockfall is essential in managing their risk to transportation infrastructure. Precipitation and freeze-thaw (FT) are widely studied rockfall triggers, but developing reliable, quantitative methods to forecast rockfall in response to weather events remains challenging. Terrestrial laser scanning (TLS) is a powerful tool for high-accuracy modeling of rock slopes, but the frequency of scanning is often too low to correlate rockfall behavior with weather events or seasonal trends. We conducted a TLS campaign between 2017 and 2022 in Glenwood Canyon, Colorado, to investigate the seasonal variability in rockfall triggering and conditioning mechanisms. A total of 44 scans were collected over 5 years and were processed to allow for consistent detection of rockfalls larger than 0.0036 m3 in volume. Meteorological variables relating to precipitation, snowpack, and temperature were modeled using the National Weather Service SNODAS product and were used to complete an exploratory analysis of the correlation of various weather indices with rockfall rate over time. It was found that the short-term sum of liquid precipitation and snowmelt (averaged over the scanning interval or the max single-day total) was a strong predictor of rockfall volume rate between 2018 and 2020, especially in the spring and summer months; a linear model of max daily liquid was able to explain 65% of the variance (R2adj) in rockfall volume rate in March through August. This implicates springtime snowmelt and rain-on-snow events as strong predictors of rockfall at the study site. We interpret these observations to indicate that snowmelt and rainfall are acting to trigger blocks that have been conditioned (destabilized) over the preceding winter. [ABSTRACT FROM AUTHOR]

Traditionally, the reliability of a rock slope is evaluated based on the linear Mohr–Coulomb strength criterion, neglecting the nonlinear shear strength of the majority of geotechnical materials. The paper proposes a probability method to assess the reliability of rock slopes based on the power-type nonlinear strength criterion and the mean-value first-order second-moment method. In the proposed method, a novel analytical method to determine the safety factors of slopes with plane failure is derived based on the power-type nonlinear strength criterion. The local mean value of a random variable on the failure surface is determined based on the two-dimensional random field theory, avoiding the random field simulation. To quickly search the minimum reliability index βmin, a dichotomic search method is proposed. The validity of the proposed method is demonstrated in two cases. The study results from the two cases illustrate that the proposed method has high computational efficiency and accuracy. The proposed method offers a fresh way to examine the reliability of rock slopes when the nonlinear strength criterion is adopted. [ABSTRACT FROM AUTHOR]

Rock slopes with weak intercalated layer are prone to slide because of engineering disturbance or water intrusion deterioration, which poses severe threats to human life and property safety. Identifying the water-induced deterioration characteristics of such interfaces, as well as the potential failure mechanism of such slope is of great importance for scientific prevention. The right abutment slope of Gushan Reservoir is composed of thick quartz sandstone and thin argillaceous shale interlayer inclined downstream, dip angle of about 10°. Besides, relief joints with a steep tendency to the valley at the top of the slope were found. Once the shear strength of the shale decreases due to the reservoir impoundment, the slope might slide, threatening the safety of the dam. For this reason, basic data of the slope were presented by field geological and UAV aerial survey. Then, the strength deterioration law of shale induced by water was revealed by large in-situ direct shear tests. Finally, the potential failure mechanism of the slope under different conditions, as well as the feasibility of the proposed reinforcement scheme were analyzed utilizing three-dimensional numerical simulation. The results showed that the shear strength of the saturated shale was about 50% of that under natural state. The stability of the slope would decrease due to the strength deterioration of the weak interlayer, and the sliding along the weak layer might occur, resulting in local deformation at the right end of the dam. Concrete plugs to be arranged along the potential sliding surface was an effective reinforcement measure for such slope. These results might provide a reference for the stability evaluation and reinforcement design of similar slopes. [ABSTRACT FROM AUTHOR]

A cyclic loading may be responsible for reversible and irreversible movements of rock blocks along pre-existing fractures, serving as a preparatory factor for rockfall with cumulative effects over time. The mechanism associated with this hypothesis posits that thermally induced deformations may be sufficient to generate irreversible movements through the contraction and expansion of rock blocks. This study aims to investigate the mechanical and hydraulic behavior of discontinuities in gneissic rock under prepeak cyclic shear loading to identify irreversible displacements for the study of rock block falls. Cyclic shear tests were conducted on fractured rock samples, varying the values of the Joint Roughness Coefficient (JRC). The applied normal stress ranged from 100 to 1,000 kPa, while the adopted frequencies were 0.1 and 0.01 Hz. This approach ensured an almost static character in the tests, reproducing the conditions of block displacement on a rock slope. The overall analysis of the results indicated that pre-peak shear stress, associated with low normal stress (100 kPa) and low frequencies (0.1 and 0.01 Hz), was sufficient to generate irreversible accumulated displacements over cycles. Additionally, it was observed that samples with higher JRC values exhibited larger hydraulic openings. [ABSTRACT FROM AUTHOR]

To prevent landslides, the slope is a crucial component that needs to be evaluated. Mining activities produce slopes, both natural slopes and artificial slopes, and if a slope is not designed properly, its stability will be adversely affected. The purpose of this study is to determine the stability of a slope supported by sedimentary rocks as the constituent material of the slope. Data processing is carried out using the RS2 Version 11 software and finite element methods (FEMs) by considering the value of the strength reduction factor (SRF) and maximum displacement of the slope. The results obtained for stage 1 show that a maximum displacement of 0 m was obtained, along with a critical value of SRF = 1. A maximum displacement of 0.2 m was obtained in stage 2, with a critical SRF of 1.25. In stage 3, 0.2 m was the highest attained displacement, and the critical SRF was 1.26. A maximum displacement of 0.4 m and a critical SRF of 1.31 were found in stage 4. The maximum displacement in stage 5 was 0.8 m, while the critical SRF was 1.34, and the critical SRF in stage 6 was 1.35, while the maximum displacement was 0.8 m. Finally, the maximum displacement in stage 7 was 1.6 m, while the critical SRF was 1.36. A general pattern emerged from the results of stages 1 through 7. Specifically, the maximum permitted displacement value increased with the critical value of SRF. As the slope moved, it also became more stable, with a big critical SRF. If a slope's deformation exceeds 1.6 m, it will collapse at a safety factor of 1.36. Furthermore, the contour level showed that the factor of safety (FoS) falls between 1.4 and 4.2. Additionally, as sigma 1 and 3 increase, the resulting FoS value increases as well. [ABSTRACT FROM AUTHOR]

On 12th August 2015, a massive rapid long run-out rock landslide occurred in the Shanyang Vanadium Mine in Shaanxi Province, China, which claimed the lives of 65 miners. No heavy rainfalls, earthquakes, and mining blasts were recorded before the incident. Therefore, the failure mechanism and the cause of the long run-out movement are always in arguments. In this paper, we conducted a detailed field investigation, laboratory tests, block theory analysis, and numerical simulation to investigate the failure and long run-out mechanisms of the landslide. The field investigation results show that the source material of the rock landslide is a huge dolomite wedge block bedding on siliceous shale layers. Uniaxial compression tests indicate that the uniaxial compression strength of the intact dolomite is 130–140MPa and the dolomite shows a brittle failure mode. Due to the progressive downward erosion of the gully, the dolomite rock bridge at the slope toe became thinner. As the compression stress in the dolomite bridge increased to surpass its strength, the brittle failure of the bridge occurred. Then huge potential energy was released following the disintegration of the landslide, which led to the high acceleration of this rock landslide. The 3D discrete element simulation results suggest that the low intergranular friction contributes to the long run-out movement of this rock landslide. [ABSTRACT FROM AUTHOR]

An extra-large landslide occurred on June 19, 2021, on the footwall slope of the Nanfen Open-pit Iron Mine in Liaoning Province, China, with a volume of approximately 1.2×107 m3. To elucidate the causative factors, development process, and destructive mechanisms of this catastrophic landslide, comprehensive field tests, investigations, and laboratory experiments were conducted. Initially, the heavily weathered rock mass of the slope was intersected by faults and joint fissures, facilitating rainwater infiltration. Moreover, the landslide contained a substantial clay mineral with highly developed micro-cracks and micro-pores, exhibiting strong water-absorption properties. As moisture content increased, the rock mass underwent softening, resulting in reduced strength. Ultimately, continuous heavy rainfall infiltration amplified the slope's weight, diminishing the weak structural plane's strength, leading to fracture propagation, slip plane penetration, and extensive tensile-shear and uplift failure of the slope. The study highlights poor geological conditions as the decisive factor for this landslide, with continuous heavy rainfall as the triggering factor. Presently, adverse environmental factors persistently affect the landslide, and deformation and failure continue to escalate. Hence, it is imperative to urgently implement integrated measures encompassing slope reinforcement, monitoring, and early-warning to realtime monitor the landslide's deformation and deep mechanical evolution trends. [ABSTRACT FROM AUTHOR]

There exist many rock slopes with weak rocks in mines. However, long-term slope stability, especially for large-scale slopes with weak layers, still remains a challenging issue in mine projects. This study employed in-situ surface displacement monitoring and numerical analysis to assess excavation-induced effects on a high clay-bearing interbedded rock slope. A Japanese limestone quarry with a 250-meter-high rock slope intercalated by a 70-meter-thick clay-bearing rock at the footwall was used as a case study. The characteristics of the slope deformation, including the deformation rate, were first characterized by analyzing surface displacement measured by an automated polar system. Based on the measured data and the 2-dimensional finite element method, a back analysis of mining-induced deformation was performed to estimate the horizontal rock stress of the quarry and the Young's modulus of the clay-bearing rock. Thereafter, the elastic deformation of the rock slope induced by the excavation and the excavation-induced deterioration of the clay-bearing rock were evaluated. The results demonstrated that the deformation mechanism can be explained by both the deformation mechanism due to the excavation-induced deterioration of the clay-bearing rock and the horizontal stress release. Furthermore, vertical and horizontal advancing excavation patterns are proposed to clarify the deformation mechanism based on the incremental characteristics of distance changes. The findings provide useful insights into understanding the deformation mechanisms of excavation-induced deterioration of clay-bearing rock and the effect of excavation sequence patterns when interpreting the characteristics of measured surface displacement results in open-pit mines. [ABSTRACT FROM AUTHOR]

In last decades, numerical modelling become a useful tool for solving complex geoengineering problems such as slope stability. On the other hand, probabilistic slope stability analyses are able to consider the variability of the rock mass properties in the decision making process. However, the application of probabilistic slope stability analysis with large three-dimensional numerical models is still limited due to the computational expenses of evaluating a substantial number of considered models. It is well-known that response surface methodology (RSM) couples the mathematical and statistical techniques to relate input variables to the response, allowing a reliable outcome and reasonable time of the analysis. Taking these advantages, this article presents an application of RSM in probabilistic slope stability analysis using three dimensional distinct element modelling. For this purpose, the most influencing factors including: uniaxial compressive strength, geological strength index (GSI), and shear strength of discontinuities, were taken into consideration to determine the probability of failure of an open pit slope located in vicinity of a block caving-induced subsidence crater. Numerical analysis of slope stability was conducted for an open pit slope using the Distinct Element Method code-3DEC. Probability distribution of the factor of safety (FS) was determined and possible slope failure mechanism was observed. In addition, the block caving-induced subsidence was investigated. The final outcomes indicate that Response Surface Methodology is applicable when couples with numerical modelling of complex issues, GSI is considered the most influential variable. The studied slope is considered stable due to the low value of the FS probability distribution (2.2%). This research is expected to provide a reference for slope stability analysis in case of transition from Open Pit to Underground Mining. [ABSTRACT FROM AUTHOR]