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Objective The impact and fracture of rockfall are important reasons for the difficulty in predicting movement trajectories, and the geometric characteristics of slope bodies are key factors affecting the movement. Methods To study the crushing process of rockfalls and the influence of slope geometry characteristics on the movement of rockfall blocks, discrete element method (PFC2D) simulation technology was used to establish a rockfall free-fall-impact model to analysethe rock mass structure and slope geometry characteristics of typical rockfall disaster points. The fragmentation process of rockfall under different fall heights and impact angles is analysed, and the block motion velocity, crack number and impact force are obtained. Moreover, the two-parameter Weibull distribution is used to describe the fragmentation degree of blocks. Results The experimental results reveal that the fracture process can be divided into three stages: Contact-disintegration, extrusion-fragmentation and independent movement. Rock mass fragmentation starts at the impact point, disintegration occurs along the structural plane first, and fragmentation occurs on the new fracture plane. Sudden changes of the block velocity, crack quantity and impact force occur in the contact-disintegration and compression-fragmentation stages. The block velocity plummets, exhibiting a "step effect", and the impact force rises sharply, revealing a "double peak phenomenon". Moreover, when the fall height increases or the impact angle decreases, the "step effect" and "double peak phenomenon" become more obvious. Under the same impact angle, an increase of the fall height results in the increase of impact kinetic energy, thus increasing the degree of fragmentation and decreasing the particle size distribution range and characteristic particle size. At the same fall height, an increase in the impact angle causes that the contact area is reduced, and the degree of breakage is reduced, increasing the particle size distribution range and characteristic particle size. Conclusion The present results provide technical support for revealing the impact fragmentation mechanism of rockfall slopes and predicting the trajectory of block motion.

The study of rock slope stability and evolution suffers from many uncertainty factors related to block size and shape, and slope morphology. While nothing can be done to remove the aleatory component of these uncertainties, efforts in reducing the epistemic ones are desirable. This research aims to propose a new analytical solution for calculating rock block volume in the case of three discontinuity sets whose orientation and true spacing are known. Researchers and practitioners can take advantage of such a correct analytical formula thanks to its easiness of use: guidelines based on stereogram are provided in order to explain how to obtain the required input data. The correctness of the equation is demonstrated by comparing the results of the new solution applied to 12 theoretical blocks with those obtained with 3DEC (Itasca Consulting Group). Also, the differences with respect to results obtained with the well-known Palmstrøm's formula are reported. The new methodology is applied to the case study of Elva valley road (Northern Italy), which is overhung by steep rocky cliffs and is subject to the consequences of frequent rockfall phenomena. The results are used to discuss the proposed method's applicability: while it is evident that such a formula is not able to compete with the great potentiality of DFNs, this user-friendly tool can quickly and at no cost assess rock block volume in rockfall or rock slope stability studies. Highlights: The correct analytical solution for calculating rock block volume is demonstrated. The formula is valid in the case of three discontinuity sets. Orientation and true spacing of the three sets are the input of the formula. Validation is performed through a Discrete Fracture Network generator. [ABSTRACT FROM AUTHOR]

Rockfall frequently occurs in the mountainous areas and threatens structures such as settlement areas, transportation lines, and agricultural field. The empirical approaches for rockfall mapping have been an attractive research topic in rock mechanics in the recent years, because producing rockfall maps of large areas by using the deterministic and the probabilistic analysis seems difficult due to the necessity of numerous inputs. The cone propagation approach is preferred as a practical tool particularly in the regional scale. The digital elevation model (DEM) of a region prone to rockfall is used for determination of possible propagation zones based on a simple geometric rule known as the energy line angle (reach angle). As a new term, ELAmax_stop was defined to represent the energy line angle that extends to the border of the propagation zone as the maximum run-out distance that is obtained from application of the cone approach to all points (pixels) in source area. The angle denoted as α refers to the threshold slope angle of the steep areas utilized to identify potential source areas by using DEM. Conceptually, the fallen rock blocks within a rockfall-prone region stop within the cone propagation zone, which is bounded by the energy line angles α and ELAmax_stop. While the value of α is susceptible to the resolution of DEM, ELAmax_stop, which exhibits a wide angle range as documented in the literature, is controlled by rock block features together with slope surface properties of the propagation zone. Due to the variability of ELAmax_stop and α depending on the studied region and the resolution of the DEM, the boundary value of the energy line angles between different susceptibility classes need to be adjusted by considering α and ELAmax_stop. By adopting the cone propagation approach to enable adjustable use of energy line angles for rockfall susceptibility mapping, a series of graphical presentations was prepared. These graphical presentations allowed for the prediction of energy line angles corresponding to various rockfall susceptibility classes including very low, low, medium, high, and very high. In addition to the graphical presentations, a series of practical equations were derived for the same purpose. In the final part of the study, a new rating system, namely the run-out distance rating (RDR), was introduced for the preliminary determination of ELAmax_stop. Due to the empirical structure of the methodology, the suggested supportive approach to the practitioners for determining ELAmax_stop should be considered as an initial step that opens to improvement. The proposed methodology in this study was implemented in the regions of Kargabedir Hill and Sivrihisar residential areas in Turkey to prepare rockfall susceptibility maps. [ABSTRACT FROM AUTHOR]

A common practice in mountainous areas for rockfall protection is to cover the top slab of a rockfall shed with a thick granular layer to buffer the impact. However, the weight of the sand is significant, with limited buffering capacity. This paper proposes a novel composite cushion consisting of a flexible buffer and a sand layer. Full-scale rockfall impact tests of 500 kJ were conducted to evaluate the performance of the cushion. Based on the sand layer impact test, DEM parameters for simulating sand were calibrated, and a numerical model of the composite cushion with rockfall impact using FEM-DEM coupling method was constructed. The buffering performance of the composite cushion was compared with the EPS-sand cushion. The study further investigates the effect of buffer height, sand layer thickness, and rockfall mass on impact force and energy distribution using numerical simulations. The results show that (1) the impact force on the composite cushion decreases by 73.2% compared to the sand layer. (2) The buffering performance of the composite cushion is equivalent to that of the 1 m EPS + 0.4 m sand cushion in terms of inhibiting the stress development on the shed slab. (3) The superior buffering performance of the cushion is attributed to the high flexibility of the net and the force-controlling characteristics of the energy dissipaters. Meanwhile, the sand layer plays more of a secondary defense role to prevent direct collision between the rockfall and the shed slab. These findings provide theoretical bases for the engineering design of such composite cushions. [ABSTRACT FROM AUTHOR]

Protecting pipelines from impact load due to rockfall in mountainous regions is a challenging problem. Many researchers have studied rockfall characteristics and impact loading, however, there is still a lack of large-scale studies about the impact of rockfall on steel buried pipes. In this study, three large-scale tests were carried out to investigate the response of steel buried pipe, including rock penetration, impact force during penetration, circumferential strain, and vertical deformation of the pipe under different falling heights of a large spherical mass. In order to establish a well-based connection between prototype and large-scale models, a comprehensive scaling rule was applied in a way that the response of the prototype and large-scale models approached the same values. The results showed that increasing drop height causes an incremental rate of peak deceleration of the falling mass, and therefore larger impact forces were measured on the trench surface. The equivalent stiffness of the soil-buried pipe system during the impact load proved that the response of the system was mostly governed by the soil rather than the pipe. For this study, the through-wall bending stress of the pipe at drop heights of 3.5 and 4.5 m exceeded the recommended permissible range, and so failing to satisfy this design criterion. [ABSTRACT FROM AUTHOR]

Steep slopes in soft rock are characterized by their susceptibility to instability (rockfall, rockslide) due to weathering and erosion of the slope surface. This article deals with the problem of adapting to the increasing height of the scree slope. The construction of a retaining wall in a scree slope in front of a slope of soft rock with a steep face, where a very rapid weathering and erosion process of weathered material takes place, and the simultaneous deposition of material in front of the steep slope is a common solution. Changes in the geometry of the slope and the front scree are taken into account, and at the same time, sufficient safety against rockfall must be ensured. The analysis is shown on a specific example of a steep flysch slope near Split, Dalmatia. The retaining wall solutions are compared in terms of function, cost and sustainability. The construction of a single colossal, reinforced concrete retaining wall shows that this solution is not feasible due to the high construction costs and CO2 emissions of the retaining wall. A model was therefore developed to determine the height of the retaining walls for different construction time intervals and distances from the original rock face. The critical failure modes were investigated for various retaining wall solutions with regard to the highest degree of utilization of the resistance, which also allows the cost-optimized solutions to be determined. By building two or more successive retaining walls at suitable intervals and at an appropriate distance from the original rock face, construction costs and CO2 emissions can be significantly reduced. [ABSTRACT FROM AUTHOR]

Rockfalls can pose a significant threat to traffic safety in mountainous areas. Galleries covered by a granular layer have proven effective in protecting both the people and the infrastructure from falling rock blocks. However, quantifying the impact for structural design purposes remains challenging as this force is strongly influenced by the shape of the blocks, among other factors. Here, we propose a semi-empirical model to evaluate the maximum value of the impact force exerted by an irregularly-shaped rock block on a granular layer. The model introduces a work-energy ratio (α), which is a dimensionless parameter that depends on properties of both the block and the granular layer. We evaluate a significant dependence of α on the block shape (N*) as well as on the thickness (Ts) and strength-like indentation resistance (f*) of the granular layer. We show that α is lower for blocks with sharp noses (low N*) and for layers with low f*. Furthermore, we identify a threshold value of Ts, above which α becomes independent of Ts. We validate our model on large-scale experiments as well as on a variety of published data and compare the model's performance with that of existing models. The model exhibits superior performance in realistic rockfall scenarios, suggesting a good potential for implementation in gallery design. [ABSTRACT FROM AUTHOR]

This study investigates the behavior of rockfall protection on a reinforced concrete semicircular shed against impulse excitation forces by using finite element software ABAQUS and experimental analysis on a free-fall impact test machine. There is limited field knowledge about the response of rockfall protection reinforced concrete semicircular sheds under free-fall impact. The experiments are carried out through the 0.5-m center-to-center diameter of a semicircular reinforced concrete (RC) shed which has a 1.2-m length. The shape of the impactor is cylindrical with a free-fall height of 2.4 m on a semicircular reinforced concrete shed from a free-fall impact test machine. Conventional explicit analysis in finite element software ABAQUS was employed. The concrete damaged plasticity, Johnson–Cook plasticity, and Drucker–Prager models were used to mimic the reaction behavior of concrete, reinforcement, and soil, respectively. The findings from the finite element program ABAQUS were compared to the experimental data, which were found to be in close agreement. Furthermore, the simulation was carried out on the effect of important parameters such as variation in the velocity of the impactor, lining thickness, and length of the RC shed to predict the behavior of reinforced concrete shed. [ABSTRACT FROM AUTHOR]

On March 18, 2021, at 00:04 UTC, a strong earthquake (Mw 6.0) hit Bejaia city, 200 km east of Algiers. Its epicenter was 15 km northeast of Cap Carbon in Bejaia Bay, making it the largest earthquake recorded offshore since the devastating earthquake (Mw 6.8) in Boumerdes on May 21, 2003. The earthquake had a maximum intensity of VII (EMS 98), triggering hundreds of aftershocks and damaging 2000 houses and social infrastructures, as well as causing several rock falls along the rocky coastline, but no human casualties were reported. The waveform inversion and spectral analysis of the mainshock and its largest aftershocks indicate an alignment along an E-W thrust fault plane offshore, dipping southward, the mainshock seismic moment of M0 = 9.7e + 17 N.m. corresponding to a magnitude Mw = 6.0. The aftershocks illuminated a surface 22 km long (N–S) and 12 km wide; their statistical parameters were assessed by Guttenberg–Richter relationship, Omori decay, and temporal clustering. The b-value is estimated at 0.83, the p value at 0.95, and the n-value at 0.75 (i.e., 75% triggered events), which follows classical patterns of aftershock sequences and suggests the sequence tectonic genesis. Furthermore, previous studies showed that the epicentral area was positively charged by coseismic static stresses transferred from recent events in the Bejaia–Jijel margin. Exactly one year later, on March 19, 2022, a moderate earthquake struck the same epicentral zone, 3 km NW of the first shock, generating a moment M0 = 8.5e + 16 N.m. corresponding to a magnitude Mw = 5.3; its focal mechanism also revealed an E–W striking reverse fault with a small strike-slip component. The present-day local stress field is characterized by a contractional tectonic regime (R′ = 2.99 ± 0.24) and σ1 orientation (N345°E) consistent with the maximum regional compressive stress direction (NNW–SSE). The 2021–2022 Bejaia Bay seismic sequence underlined the active tectonics linking the major E–W offshore thrust fault system and the NW–SE strike-slip Babors Transverse Fault system. This sequence, along with a number of other earthquakes that occurred around the Lesser Kabylia Block (LKB) over the last decade, likely highlights the ongoing incipient subduction process between Africa and Eurasia along the northern Algerian margin. [ABSTRACT FROM AUTHOR]

Rockfalls can often pose a significant risk to the public if protective designs do not properly account for block movement downslope and onto infrastructure facilities. Assessing these hazards is challenging, especially as current empirical and computational methods for predicting trajectories of falling blocks generally do not include the contribution associated with rotational behavior. Research undertaken at the University of New Hampshire, USA, over the last decade has led to the development of Smart Rock (SR) sensors inserted in natural rocks to evaluate these events from the perspective of the falling rock. The latest SRs consist of 3 D printed capsules 58.0 mm in length and 25.4 mm in diameter, equipped with a ±400 g and a ±16 g 3-axis accelerometer, a ± 4000 dps high-rate gyroscope, and an altimeter. Approximately 80 field experiments conducted in New Hampshire and Vermont provided SR data on rockfall at ten different sites. The Smart Rock data allowed more in-depth evaluations of accelerations, rotation rates, and modes of motion with precise time intervals, which cannot be easily captured in video recording systems or other instrumentation techniques. Such measurements are essential to improve our understanding and modeling of rockfall events for more economical and safer design of protective systems. [ABSTRACT FROM AUTHOR]

The occurrence of rockfalls is a prevalent geological hazard, especially in the Three Gorges Reservoir area of the Yangtze River. Analyzing the pre-rockfall evolution process of hazardous rock mass is crucial for stability assessment, risk monitoring, and evaluation. Generally, numerical analysis is conducted to study the rock stability and failure; however, it is primarily based on the two-dimensional calculation of typical cross-sections without considering the shape of the three-dimensional space of the hazardous rock mass, thus leading to distorted results. To address this issue, this paper proposes a methodological approach for the analysis of the stability conditions of a hazardous rock mass. The approach starts with field investigations and an Unmanned aerial vehicle (UAV) photogrammetric survey to gather data. These data are then used to construct a three-dimensional (3D) geological model of rock mass. Finally, a 3D numerical simulation is performed to analyse the potential failure processes of hazardous rock mass. In this study, we focused on the hazardous Diaozui rock mass of the Qutang Gorge in the Three Gorges Reservoir area (China). We constructed a 3D geological model of the rock mass based on the data from the field survey and UAV photogrammetric survey. Using this 3D geological model, we established a 3D numerical analysis model to assess the rockfall hazard. By utilizing the Strength reduction method (SRM) and simulating the collapse process of the hazardous rock mass, we analyzed the instability mechanism and failure evolution process of the Hazardous Diaozui rock mass. The results illustrated the potential failure mode, the key-oriented wedges of the rock mass, and the potential critical failure point for the hazardous rock mass. These findings provide valuable insights for stability assessment, risk monitoring, and evaluation of the hazardous rock mass in the Three Gorges Reservoir area. [ABSTRACT FROM AUTHOR]

This study focuses on the characterization of low-velocity (lower than 100 km/h) rockfall impact loads transferring to a thick steel-reinforced concrete (SRC) slab through a protective sand layer. A full-scale experimental test campaign was performed, where each test consisted of releasing a concrete block which, after a vertical free fall, impacts a sand protective layer placed over a SRC slab, in order to represent an isolated rockfall impact to which an actual SRC structure could be exposed. During the impact, the vertical pressure distribution was observed using several pressure cells installed at the sand–slab interface. A total of 35 tests were carried out, systematically combining sand layer thickness (D), block's equivalent diameter (B), and free-fall drop height (H), related to impact velocity. The masses of the released blocks were in the range of 117 to 7,399 kg, corresponding to diameters in the range of 0.42 to 1.79 m. Five free-fall drop heights up to 33 m were considered to reach impact velocities up to 90 km/h , covering the range of most velocities observed in actual rockfall studies. Three thicknesses of the sand layer protecting the thick SRC slab were considered: 1, 1.5, or 2 m. Data reduction from this full-scale impact tests program makes it possible to characterize, for a given thickness of protective sand layer, the time-space pressure pulse distribution applied to the protected structure during the impact for a large range of rock boulder masses and speeds actually observed in the field. [ABSTRACT FROM AUTHOR]

The Heshui area within the Ordos Basin holds significant strategic importance for the extraction and development of tight oil resources in the Changqing Oilfield. This study extensively explored the geochemical features and distribution tendencies of source rocks in the Chang 7 member, utilizing core samples and logging data for a comprehensive analysis. A more advanced model was utilized to predict the dispersion of Total Organic Carbon (TOC) in the Chang 7 member source rock. The properties and hydrocarbon generation potential of source rocks were thoroughly assessed through a comprehensive analysis that involved evaluating their total organic carbon content, pyrolysis parameters, and reflectance (Ro) values. The research concluded that the source rocks boast substantial organic matter, predominantly categorized as type II-I organic material. The thermal maturation levels span from low maturity to maturity, signifying significant potential for oil generation. Generally, the source rock quality falls within the range of good to excellent. Sedimentary patterns notably influence the distribution of hydrocarbon-source rocks. The northeastern sector of the study area is situated in an area characterized by deep to semi-deep lake sedimentation, making it the primary location for the presence of Chang 7 member hydrocarbon source rocks. With a thickness ranging from 40 to 70 m, this zone becomes a pivotal focus for the potential exploration of tight oil resources in the future. The results of this study offer crucial insights for understanding the geochemical characteristics of hydrocarbon source rocks, evaluating their potential for hydrocarbon generation, and forecasting favorable zones for oil and gas exploration in similar regions. [ABSTRACT FROM AUTHOR]

Urban floods/inundation disasters are becoming a prominent problem affecting urban public security due to the impact of global climate change and rapid urbanization. Therefore, research on urban flooding via numerical modelling has important practical significance. According to hydrological and hydrodynamic theories and methods, based on the Storm Water Management Model and the self-developed Graphics Processing Unit (GPU) Accelerated Surface Water Flow and Associated Transport (GAST) model, we explore the best coupling mode, and take Xiaozhai block in Xi'an, China, as the research object to study, through the selected mode, the impact of the change of local land use type on surface inundation and pipe network. The results show that the hydrology–hydrodynamic coupling model (G-S) is more realistic, and its simulation results are more in line with the actual urban flood processes. The results are expected to provide help to other experts and scholars in future model coupling research. [ABSTRACT FROM AUTHOR]

Steep alpine rock slopes undergoing deformation may give rise to concurrent landslide hazards of different type and magnitude. The underlying mechanisms of instability are often challenging to investigate due to their inherent complexity; furthermore, they can occur on poorly accessible terrain, preventing the collection of data by means of traditional field techniques or even inhibiting awareness of hazards. This paper focuses upon one such case, in which a major transportation corridor running along the floor of the Aosta Valley (Western Italian Alps) is affected by significant—and until recently unknown—rockfall hazards promoted by a previously collapsed rockslide still deforming slowly at elevations almost 600 m above the road. In particular, two large discrete blocks (volume > 103 m3) lie precariously at the toe of the slide and could fall downslope at extremely rapid velocity. The design of countermeasures for the stabilization or removal of these blocks would require the assessment of their mechanical interaction with the bedrock and degree of internal fracturing (i.e., possible pervasive damage within the blocks). We perform this task by first exploring potential kinematic styles and damage patterns at failure according to a series of preliminary finite-element models. We then use detailed displacement measurements from remote sensing and in situ monitoring, in conjunction with repeat topographic surveying from a terrestrial laser scanner (TLS) and a drone laser scanner (DLS), to reconstruct the actual kinematics of the blocks. The results substantiate the hypothesis that instability is primarily controlled by transient degradation of friction on a through-going basal rupture surface. Development of a large tensile fracture in one of the two blocks is inferred to be conditioned by increased non-planarity of the slipping joint in comparison with the other block. We highlight that optimized integration of cutting-edge rock slope investigation tools can help address otherwise unresolved key aspects of complex instabilities in steep mountainous areas. Highlights: Two large discrete blocks at the toe of a slowly deforming and highly disaggregated rock slope pose significant concerns to a major transportation corridor in the Western Italian Alps. Knowledge of the underlying mechanisms of instability is required to design mitigation measures, but traditional site characterization is impossible due to difficult terrain. Preliminary numerical modelling, slope monitoring, and repeat topographic surveying are integrated into a coordinated analysis framework to explore kinematic styles, damage patterns, and overall modes of failure. It is shown that the blocks are likely affected by transient degradation of friction on a through-going basal rupture surface of varying roughness, and translate towards the steep apex of the adjacent talus cone as mostly individual entities with negligible influence of brittle fracture damage. [ABSTRACT FROM AUTHOR]

Typical rockfall analysis requires detailed discontinuity measurements; however, the use of conventional contact approaches can be challenging on cliffs. In this study, a novel automatic method for rockfall susceptibility is proposed to identify potential rockfall areas by topographic information on steep slopes generated by a terrestrial laser scanner (TLS). The rockfall susceptibility can be determined using the proposed method via the following four steps: first, automatic spatial information of discontinuity extraction based on high-resolution point clouds; second, defining the spatial intersection areas of discontinuities with different statistical properties; third, evaluating the contribution of discontinuity intersections to rockfalls and estimating potential rockfall hazardous blocks based on kinematic analysis; and finally, mapping the rockfall susceptibility through the overall index. Our method can be used to expedite discontinuity measurements from high-resolution point clouds, optimize the processing of discontinuity statistics for the analysis of rockfall source areas, and permit users to visualize and intuitively access potential rockfall areas to facilitate effective measures to control rockfall hazards or implementation. The method was implemented in MATLAB for excavated slopes, and the credibility of our computational results was verified by visual inspection and a comparison to the source locations of rock detachment events. The results showed that the areas in case 1 with a high susceptibility were in line with the geometry of the discontinuities, and the predicted potential failure areas in case 2 were consistent with the rockfall events. This automated process allows rapid acquisition of potential rockfall areas over a broad-scale survey area, which helps to reduce the time of investigation and the uncertainty in further treatment. Highlights: An automatic mapping method based on high-resolution point clouds was utilized for rockfall susceptibility evaluation. An evaluation method was proposed for potential hazardous rockfall blocks based on discontinuity extraction and kinematic analysis. The method was implemented in MATLAB and validated by actual rockfall events on an excavated slope. [ABSTRACT FROM AUTHOR]

Ischia (Southern Italy) is a volcanic island of the Phlegrean Volcanic District that was historically affected by multiple geological hazards, including floodings, landslides, rockfalls, and earthquakes. In this study, rockfall stability is analysed with an integrated approach aimed at investigating the rockfall source, the propagation, and the deposition areas. The case study is represented by two outcrops over a 400-m-wide cliff made of Green Tuff and located on the western area of Mt. Epomeo. They are respectively located at 280 and 420 m a.s.l., just uphill the village of Frassitelli, Forio d’Ischia, which is an area of high residential, tourist, and agricultural importance. We analysed the fracture systems of the tuff cliff to compute the kinematic analysis of the potential failure mechanisms and to perform numerical simulations of rockfall scenarios. Successively, numerical simulations of rockfall scenarios were computed based on the acquired structural information. This allowed us to identify the most hazardous scenarios based on the rock trajectories and the percentage of rock blocks affecting the urban area. The influence of the rock shape and volume on the rockfall trajectories was analysed. In the most likely scenarios, we observed that 15–25% of the rock blocks bypass the geomorphological barriers and reach the urban area, with kinetic energy values spanning between 102 and 104 kJ. Such detailed rockfall hazard analysis allowed the definition of the mitigation interventions necessary for the protection of the nearby residential area. [ABSTRACT FROM AUTHOR]

The impact effects of falling rocks on sand–reinforced concrete slab composite protective structures involve several factors. Among them, the existing codes are unable to consider the effect of rockfall shape and the angle of contact between the rockfall and the object on the impact force as well as the depth of penetration. Based on extensive field investigation, this paper proposes a shape factor to simplify the rockfall into an ellipsoid and determines the shape and dimensions of the rockfall by three-dimensional axis length. Besides, a coupled SPH-FEM numerical calculation model is established and validated through comparison with a large-scale outdoor test of a rockfall impact protection structure. Finally, the effects of rockfall shape and impact angle on the symbolic parameters including impact force, impulse and energy in the impact process are revealed. The findings indicate that the maximum force and displacement of the midpoint of the bottom of the reinforced concrete slab have relative errors within 5.0 % when compared to the model test, confirming the precision of the models discussed in this paper. For the same rockfall, the peak force decreases with the impact angle increasing; taking the same volume of spherical rockfall as the reference, under the same rockfall pattern, the peak impact force and impulse amplification factor decreases with the increase in contact attitude angle. Additionally, the scaling effect becomes more pronounced when the shape factor of the rockfall is smaller; under the same shape factor, the impact depth of the cushion layer is the smallest when the attitude angle is 45°, and the maximum when the impact angle is 90°; the SPH-FEM coupling algorithm could reasonably reproduce the pit-forming process of sand and soil, and it is very effective in simulating the flow effect of soil particles under impact.

Rockfalls in mines represent one of the most hazardous events for miners, posing significant risks to safety, equipment, and operations. These incidents occur when rock or debris falls from the walls of a mine, often without warning, and can be triggered by geological factors, blasting practices, ground vibration, water infiltration, stress redistribution and timedependent behaviour of rock. Apart from this, the bench parameters, such as the slope angle of the bench, the friction angle of the material, bench height and width, affect the rockfall. The rockfall incidents history that occurred in the past several years suggest that rockfalls in opencast mines led to the fatal injuries of many individuals. The problems faced due to rockfalls are not repetitive, but they are disastrous in opencast mines once they occur. So, it is necessary to investigate the rockfall in an opencast mining industry. It is also observed from the literature that the kinetic energy of a rockfall helps determine the intensity of rockfall in a mine. Understanding these factors and implementing preventive measures and rapid response strategies is crucial in mitigating rockfall risks. Hence, this study investigates rockfall phenomena in a high wall open cast by determining the kinetic energy of a rockfall. A parametric study has been conducted to determine the effect of various bench parameters on the kinetic energy of rockfall. A predictive model is developed to determine the kinetic energy of rockfall concerning various factors affecting rockfall. The predictive model is also validated using three case studies of high opencast mines. The results from the predictive model and the numerical model for the case study mines match the predictive model that can predict the rock fall intensity for opencast mines. The study also aims to assess the potential risks posed to workers, equipment, and infrastructure in highwall opencast mines. The findings provide valuable insights for implementing appropriate safety measures and developing effective strategies to mitigate rockfall hazards. [ABSTRACT FROM AUTHOR]

Reinforced concrete (RC) structural members could be subjected to impulsive impact loads due to various effects such as the collision of masses driven by rockfall, flood, landslide, avalanche, the crash of vehicles to structural elements in highway and seaway, airplane landing contact, the acting of explosion-induced air shock waves on structural elements as impulsive loads. The conventional design of RC slabs and similar structural members is carried out regarding vertical static and lateral dynamic loads such as earthquake and wind effects. However, the design phase mostly ignores impulsive loads such as impact and blast. Thus, these effects pose risks that the structures experience heavy damage or total collapse. Strengthening RC slabs with textile strips has become a preferred strengthening technique to prevent the collapse of structures and limit damage to structural elements. This study strengthened RC slabs with basalt textile reinforced mortar (TRM) strips in different widths, and layout patterns were tested for low-velocity impact load. In addition, the effects of BFRP fan-type anchors near the impact point on the behavior have also been investigated. The effect of various applied strengthening patterns on impact load transferred to specimens, dynamic responses such as acceleration, displacement, maximum strain, and dynamic failure modes occurred were investigated and interpreted in detail. The experimental results have also been compared with the improved finite element model (FEM) generated. It is demonstrated that the present FEM can be used to evaluate the impact response of the RC slabs with TRM strips. [ABSTRACT FROM AUTHOR]

The normal restitution coefficient of rockfall is the key parameter to determine the trajectory. The aim of the study is to reveal the influence of collision velocity and material parameters on the normal restitution coefficient of rockfall. The theoretical model of the rock sphere and the plate collision was established based on the elastic-plastic assumption. Furthermore, the collision between the rock sphere and the plate was simulated through the ABAQUS, and the velocity of the rock sphere was monitored in the collision process. The results show that numerical simulation and theoretical calculation are in good agreement, and the maximum difference is within 5% . The confining pressure causes the contact stress in the plastic zone to be greater than the elastic limit of the material. With the increase of collision velocity, the normal restitution coefficient of the rock sphere gradually decreases, and the decline rate gradually decreases. The normal restitution coefficient of the rock sphere decreases with the increase of elastic modulus and increases with the increase of elastic limit, which has a linear relationship. Poisson's ratio has little effect on the normal restitution coefficient of the rock sphere. [ABSTRACT FROM AUTHOR]

Massive sediment pulses in catchments are a key alpine multi-risk component. Substantial sediment redistribution in alpine catchments frequently causes flooding, river erosion, and landsliding and affects infrastructure such as dam reservoirs as well as aquatic ecosystems and water quality. While systematic rock slope failure inventories have been collected in several countries, the subsequent cascading sediment redistribution is virtually unaccessed. For the first time, this contribution reports the massive sediment redistribution triggered by the multi-stage failure of more than 130 000 m3 from the Hochvogel dolomite peak during the summer of 2016. We applied change detection techniques to seven 3D-coregistered high-resolution true orthophotos and digital surface models (DSMs) obtained through digital aerial photogrammetry later optimized for precise volume calculation in steep terrain. The analysis of seismic information from surrounding stations revealed the temporal evolution of the cliff fall. We identified the proportional contribution of > 600 rockfall events (> 1 m3) from four rock slope catchments with different slope aspects and their volume estimates. In a sediment cascade approach, we evaluated erosion, transport, and deposition from the rock face to the upper channelized erosive debris flow channel, then to the widened dispersive debris flow channel, and finally to the outlet into the braided sediment-supercharged Jochbach river. We observe the decadal flux of more than 400 000 m3 of sediment, characterized by massive sediment waves that (i) exhibit reaction times of 0–4 years in response to a cliff fall sediment input and relaxation times beyond 10 years. The sediment waves (ii) manifest with faster response times of 0–2 years in the upper catchment and over 2 years in the lower catchments. The entire catchment (iii) undergoes a rapid shift from sedimentary (10 2 –10 3 mma-1) to massive erosive regimes (10 2 mma-1) within single years, and the massive sediment redistribution (iv) shows limited dependency on rainfall frequency and intensity. This study provides generic information on spatial and temporal patterns of massive sediment pulses in highly sediment-charged alpine catchments. [ABSTRACT FROM AUTHOR]

On April 18, 2023, a rockslide occurred in Torkham town in Pakistan, near the border with Afghanistan. The rockslide buried trucks and people, resulting in seven deaths and many injuries. The area is prone to natural disasters such as earthquakes, landslides, and floods. The rockslide was triggered by heavy rainfall and may have been exacerbated by slope cutting for road widening. The authors recommend slope stabilization measures, such as drainage systems, vegetation planting, retaining walls, and rockfall barriers, to prevent future disasters. [Extracted from the article]

Rockfalls are ubiquitous products of landscape evolution in steep mountainous terrains. Among other effects, they pose a significant concern to the management of transportation corridors located on valley floors. Here, we describe the field application of a ground-based Doppler radar that performs real-time, long-range, wide-area detection and tracking of rockfalls and related slope hazards. We deployed the instrument at the Ruinon landslide, where accelerated deformation of upper chaotic debris has for several months promoted secondary mass wasting processes of extremely rapid velocity. In particular, large rolling boulders had the potential to propagate beyond the toe of the landslide and impact a road that connects important localities in the Italian Alps interiors. The Doppler radar was programmed to actuate a pair of traffic lights so that a predefined exclusion zone could instantly be enforced for approaching vehicles upon initial movement detection. We discuss the setup of the alarm system, the main observations collected during the monitoring campaign, and how this technique may enhance safety in areas critically exposed to rockfalls as well as our understanding of rockfall dynamics in general. [ABSTRACT FROM AUTHOR]

Different approaches exist to describe the seismic triggering of rockfalls. Statistical approaches rely on the analysis of local terrain properties and their empirical correlation with observed rockfalls. Conversely, deterministic, or physically based approaches, rely on the modeling of individual trajectories of boulders set in motion by seismic shaking. They require different data and allow various interpretations and applications of their results. Here, we present a new method for earthquake-triggered rockfall scenario assessment adopting ground shaking estimates, produced in near real-time by a seismological monitoring network. Its key inputs are the locations of likely initiation points of rockfall trajectories, namely, rockfall sources, obtained by statistical analysis of digital topography. In the model, ground shaking maps corresponding to a specific earthquake suppress the probability of activation of sources at locations with low ground shaking while enhancing that in areas close to the epicenter. Rockfall trajectories are calculated from the probabilistic source map by three-dimensional kinematic modeling using the software STONE. We apply the method to the 1976 MI = 6.5 Friuli earthquake, for which an inventory of seismically-triggered rockfalls exists. We suggest that using peak ground acceleration as a modulating parameter to suppress/enhance rockfall source probability, the model reasonably reproduces observations. Results allow a preliminary impact evaluation before field observations become available. We suggest that the framework may be suitable for rapid rockfall impact assessment as soon as ground-shaking estimates (empirical or numerical models) are available after a seismic event. [ABSTRACT FROM AUTHOR]

Gravitational processes on cut slopes located close to infrastructure are a high concern in mountainous regions. There are many techniques for survey, assessment, and prognosis of hazardous exogenous geological processes. The given research describes using UAV data and GIS morphometric analysis for delineation of hazardous rockfall zones and 3D modelling to obtain an enhanced, detailed evaluation of slope characteristics. Besides the slope geomorphometric data, we integrated discontinuity layers, including rock plains orientation and fracture network density. Cloud Compare software 2.12 was utilised for facet extraction. Fracture discontinuity analysis was performed in QGIS using the Network GT plugin. The presented research uses an Analytical Hierarchy Process (AHP) to determine the weight of each contributing factor. GIS overlay of weighted factors is applied for rockfall susceptibility mapping. This integrated approach allows for a more comprehensive GIS-based rockfall susceptibility mapping by considering both the structural characteristics of the outcrop and the geomorphological features of the slope. By combining UAV data, GIS-based morphometric analysis, and discontinuity analysis, we are able to delineate hazardous rockfall zones effectively. [ABSTRACT FROM AUTHOR]

Research on high-temporal-resolution rock slope monitoring has tended to focus on scenarios where spatial resolution is also high. Accordingly, there is a lack of understanding of the implications for rock slope monitoring results in cases with high temporal resolution but low spatial resolution, which is the focus of this study. This study uses automatically captured photos taken at a daily frequency by five fixed-base cameras in conjunction with multi-epoch Structure-from-Motion (SfM) photogrammetric processing techniques to evaluate changes in a rock slope in Majes, Arequipa, Peru. The results of the monitoring campaign demonstrate that there are potential issues with the common notion that higher frequency change detection is always superior. For lower spatial resolutions or when only large changes are of concern, using a high-frequency monitoring method may cause small volume changes that eventually aggrade into larger areas of change to be missed, whereas most of the total volume change would be captured with lower-frequency monitoring intervals. In this study, daily change detection and volume calculation resulted in a cumulative rockfall volume of 4300 m3 over about 14 months, while change detection and volume calculation between dates at the start and end of the 14-month period resulted in a total rockfall volume of 12,300 m3. High-frequency monitoring is still the most accurate approach for evaluating slope evolution from a rockfall frequency and size distribution perspective, and it allows for the detection of short accelerations and pre-failure deformations, but longer-term comparison intervals may be required in cases where spatial resolution is low relative to temporal resolution to more accurately reflect the total volume change of a given rock slope over a long period of time. [ABSTRACT FROM AUTHOR]

In this research article, we propose a practical methodology for evaluating the affecting potential of detachment areas in rockfalls. Our innovative approach combines an assessment of the visibility of rockfall source areas, with reference to specific rockfall scenarios and elements at risk, considering the rockfall Susceptibility Index to Failure (SIF) of these areas. The result is the characterization of source areas through a rockfall Source Affecting Index (SAI), which considers both the morphology of the slope and the geostructural conditions of the rock walls. This information can be very useful since it aids in optimizing more in-depth analyses, as well as the placement of monitoring instruments or stabilization systems. The proposed methodology has been implemented in the open-source software QGIS through the development of an easy-to-use plugin named Ranking of the Affecting Potential of Detachment Areas in Rockfalls, or "RADAR". RADAR is designed to be used in conjunction with QPROTO, a well-known QGIS plugin for preliminary rockfall susceptibility/hazard analyses based on a visibility analysis and a simplified mechanical method. To demonstrate the effectiveness of the proposed approach, an application to a case study located in the Western Alps (Bardonecchia, Italy) is presented and discussed in the paper. [ABSTRACT FROM AUTHOR]

Rockfall events represent a significant hazard in mountainous regions, putting human safety and critical infrastructure at risk. Various mitigation devices are available, among which, Rockfall protection embankments (RPEs) located in natural soil are passive defense work suitable for high-energy and high-frequency events. Currently, limited research has been conducted in this area, with the Austrian standard ONR 24810 providing the sole codified design method. A parametrical analysis involving both the RPE geometry and the impact features was developed by Abaqus/Explicit FEM code, with 2270 cases overall. The research aims to identify conditions under which RPEs effectively stop falling blocks, focusing on two failure mechanisms: the block pass over the RPE after impacting the upstream side bank and the RPE structural collapse. Additionally, the interaction between RPEs and their foundations during the impact is explored. The results provide valuable insights into the dynamic behavior of these structures. In terms of design considerations, this study offers analytical equations to quantify crater depth and foundation stress induced by the impact. Furthermore, design charts are developed to assess the block passing over verification and the structural collapse verification. [ABSTRACT FROM AUTHOR]

The purpose of this work is to analyze the stability of four slopes along the Penipe–Baños road, which is situated in the provinces of Chimborazo and Tungurahua and where there are occasionally rockfalls that hinder passage and endanger road users. The methodology used to conduct the analysis was based on data collection with the help of remote techniques such as structure from motion, which allows us to obtain slope data using photogrammetry. Empirical methods such as slope mass rating, Q-slope, the kinematic method and the Rockfall Hazard Rating System method were used. These methods were evaluated with Rocfall3 software for the analysis of the fall trajectory of rock blocks. The results of this work show that the slopes studied do not represent a greater risk to the road than other slopes close to those studied, but these could not be analyzed due to their lack of accessibility and the danger of obtaining data under those conditions. The study of these different methods demonstrates the reliability of low-cost, remote techniques in the facilitation of analysis in places with similar conditions. [ABSTRACT FROM AUTHOR]

Objectives: Rockfall occurs frequently in the mountainous areas of southwest China, which is easy to cause huge casualties and property losses. A rapid simulation method of the collapse process is urgently needed. At present, the commonly used collapse simulation software still has obvious shortcomings, such as low terrain accuracy, failure to consider the structural characteristics of rock mass, failure to realize block collision and fragmentation, etc., and the logic operation based on central processing unit (CPU) limits the calculation speed. A new method for rapid simulation of the three-dimensional motion process of collapse is proposed. Methods: The unmanned aerial vehicle (UAV) aerial photography modelling combined with field investigation is used to obtain the slope surface model and determine the characteristic parameters of rockfall. The simulation software of large-scale collapse movement process is developed using Unity3D platform which integrates PhysX physics engine and central processing unit-graphics processing unit (CPU-GPU) parallel computing capability. Results: The software can reproduce the whole process of collapse-impact-fragmentation-accumulation. It can output the three-dimensional trajectory, velocity, energy and jumping height of collapse, which provides reliable basis for the design of collapse prevention and control. Taking Xiejiayan collapse in Nayong, Guizhou Province as a prototype case, three-dimensional simulation and verification of the collapse movement process are carried out. The simulation results of the rockfall accumulation range are in good agreement with the field investigation of the rockfall accumulation range at the bottom of the slope, and the movement characteristics of the simulated single block rock conform to the real physical laws, which indicates the feasibility and practicability of this method. Conclusions: This method can solve the problem of simulation, analysis and visualization of the whole process of three-dimensional movement of rockfall. [ABSTRACT FROM AUTHOR]

Landslides are common across Canada and they pose hazards to human safety, economic activities, and the environment. Robust risk management strategies are necessary for sustainable development. A slope risk management framework has been adopted by the geotechnical community for approximately four decades allowing a systematic, consistent and transparent framework for managing risks. Implementing this framework is associated with uncertainties embedded in our estimates of risk. This paper presents a brief summary of the sources and categories of uncertainty in geotechnical slope engineering and focuses on two topics: (1) estimates of uncertainty in risk calculations and (2) temporal changes in landslide likelihood as a function of weather and steps towards estimating landslide risk changes with climate change. The paper argues that a quantitative risk assessment should not focus on the final risk calculation, but the overall knowledge gained. This allows comprehensive documentation of sources of uncertainty and how they impact geotechnical and risk assessments. Furthermore, the paper outlines approaches to define quantitative correlations between rock fall occurrences and weather, which can be leveraged to estimate changes in rock fall risk with climate change. The paper corresponds to, and expands on, the 2021 Canadian Geotechnical Colloquium. [ABSTRACT FROM AUTHOR]

Rockfall remains a prominent hazard for transportation corridors worldwide. Recent studies have shown promising results in resolving the relationships between rockfall activity and triggers, including in some cases detecting precursor activity prior to failure, which could have implications to improving safety and performance of transportation corridors. The aim of this study is to better understand rockfall failure processes and triggers for cut slopes in interbedded sedimentary rock through a long-term study using photogrammetry data with high spatiotemporal frequency. The combination of daily data, high-precision rockfall volume estimation, and 22-month monitoring duration is unique among studies that evaluate rockfall triggers and allows us to derive insights into differences in rockfall triggering between blocks of different volumes. The data collected allowed the relative frequency of rockfalls of different volumes to be well-constrained for volumes ranging from 0.01 m3 up to 76 m3 (the largest event that occurred during the monitoring period). A quantitative comparison between precipitation and rockfall activity established that precipitation was the primary trigger for rockfall at the site, with only 1.4% of 24-h photo intervals without precipitation having at least one rockfall, as compared to 25.0% of photo intervals with precipitation (and 57.1% of photo intervals with at least 5 mm of precipitation). The marginal impact of additional rainfall above 8 mm per 24-h period on rockfall probability was negligible among all rockfalls observed, whereas the probability of the largest rockfalls at the site (> 1 m3) occurring continued to increase as a function of precipitation up to 20 mm per 24-h period. Detailed analysis of change data leading up to the largest (76 m3) rockfall observed illustrated the progressive failure mechanism of the block, including observations of forward toppling motion and smaller precursor rockfalls around its perimeter. This rockfall was also used for a proof-of-concept demonstration of the potential for a spatiotemporal rockfall density metric to be used to help identify areas of potential hazard. Ultimately, the findings from this study contribute to knowledge on rockfall processes outside alpine regions, which have historically been less well-studied. [ABSTRACT FROM AUTHOR]

The process and dynamics of rock fragmentation during the collapse of rockfalls and rock avalanches is a poorly developed topic. The most severe fragmentation often leads to the formation of a rock dust that rises to form a cloud suspended in the air. The understanding of fragmentation processes is hampered by the environmental disturbances that alter the dust cloud deposit shortly after deposition. Here, we study the fragmentation of the October 2017 Pousset rockfall, detached from a NNE facing steep bedrock wall in the permafrost zone, that involved 8,300m3 of metamorphic rock and fell about 800 m. The collapse generated large boulders which rolled downslope and a thick and large dust cloud. The source and deposit were investigated, and dust cloud material was sampled at different locations to reconstruct an exponential thickness distribution and perform grain size characterization. The fragmentation energy was estimated by integrating the spectrum of the grains assuming that the fragmentation energy is proportional to the generated area. The fragmentation energy was found to be about 0.4% of the initial potential energy. Most probable fragmentation points and block deposition areas were evaluated and positioned by means of the HyStone 3D rockfall simulator. Furthermore, we calculated the flow rate of the suspended powder generated by the fragmentation process and compared the results with observations available for the evolution of the phenomenon and the collected samples. The Pousset event, in its relatively simple dynamics, may be a good testing ground to address the current theories of rockfall and rock avalanche fragmentation and dust cloud behavior. [ABSTRACT FROM AUTHOR]

High mountains are climate change hotspots. Quickly rising temperatures trigger vegetation shifts such as upslope migration, possibly threatening mountain biodiversity. At the same time, mountain slopes are becoming increasingly unstable due to degrading permafrost and changing rain and snowfall regimes, which favour slope movements such as rockfall and debris flows. Slope movements can limit plant colonization, while, at the same time, plant colonization can stabilize moving slopes. Thus, we here propose that response of high mountain environments to climate change depends on a 'biogeomorphic balance' between slope movement intensity and the trait-dependent ability of mountain plants to survive and stabilize slopes. We envision three possible scenarios of biogeomorphic balance: (1) Intensifying slope movements limit vegetation shifts and thus amplify instability. (2) Shifting ecosystem engineer species reduce slope movement and facilitate shifts for less movement-adapted species. (3) Trees and tall shrubs shifting on stable slopes limit slope instability but decrease biodiversity. Previous geomorphic, ecological and palaeoecological studies support all three scenarios. Given differences in ecologic and geomorphic response rates to climate change, as well as high environmental heterogeneity and elevational gradients in mountain environments, we posit that future biogeomorphic balances will be variable and heterogeneous in time and space. To further unravel future biogeomorphic balances, we propose three new research directions for joint research of mountain geomorphologists and ecologists, using advancing field measurement, remote sensing and modelling techniques. Recognizing high mountains as 'biogeomorphic ecosystems' will help to better safeguard mountain infrastructure, lives and livelihoods of millions of people around the world. [ABSTRACT FROM AUTHOR]

Over large regions exposed to natural disasters, cascading effects resulting from complex or concatenated natural processes may represent a large portion of total risk. Populated high‐mountain environments are a major concern, and methods for large‐scale quantitative risk analyses are urgently required to improve risk mitigation. This article presents a comprehensive quantitative rockfall risk assessment over a large archetypal valley of the Andean mountains, in Central Chile, which integrates a wide spectrum of elements at risk. Risk is expressed as an expected damage both in monetary terms and casualties, at different scales relevant for decision making. Notably, total rockfall risk is divided into its main drivers, which allows quantifying seismically induced rockfall risk. For this purpose, the local seismic hazard is quantified and the yield acceleration, that is, acceleration required to initiate rockfall, is determined at the regional scale. The probability of failure is thereafter derived in terms of annual frequency of rockfall initiation and integrated in the quantitative risk assessment (QRA) process. Our results show the significant role of seismic activity as the triggering mechanism of rockfalls, and highlight elements at risk that have a major contribution to the total risk. Eventually a sensitivity analysis is conducted to (i) assess the robustness of obtained risk estimates to the data and modeling choices and (ii) identify the most influential assumptions. Our approach evidences the feasibility of large‐scale QRAs in sensitive environments and opens perspectives for refining QRAs in similar territories significantly affected by cascading effects and multihazards. [ABSTRACT FROM AUTHOR]

This paper evaluates the relation between rockfall events and weather conditions for two regions in Norway – Romsdalen and Gudbrandsdalen and explores how rockfall frequency might change with future climate conditions. Our analysis focuses on understanding the relationship between rockfall occurrence and effective water inputs, including rainfall and snow melt, and temperature oscillations both in cold conditions (freeze-thaw cycles) and in warm conditions (hot-cold cycles). To accomplish this, regional weather data and rockfall information in the Norwegian Mass Movement Database have been employed. Our results indicate that temperature oscillations might be better suited than effective water input to depict the occurrence of rockfalls in the two study areas in Norway. Freeze-thaw cycles are most frequent during winter and spring, and hot-cold cycles are most frequent during summer. Climate change will affect rockfall seasonality and the frequency in which freeze-thaw cycles and hot-cold cycles are observed. Thus, altering the exposure of population and infrastructures to rockfalls. [ABSTRACT FROM AUTHOR]

Rockfall has become one of the deadliest geohazards in Southwest China and how to comprehensively and effectively assess rockfall hazards is an urgent challenge to overcome. Additionally, comprehensive characterization of fractures on rock mass outcrops is a prerequisite for detecting potential rockfall. In this paper, an image and point cloud-based data fusion technique is applied to characterize regional rock mass fractures. Firstly, the performances of three classical computer vision algorithms are compared and SegFormer is selected as the appropriate base model for fracture detection. After that, according to the coordinate projection transformation criterion, the detected fractures are mapped to the point cloud. The parameter information obtained through fracture characterization is used to develop a representative three-dimensional discrete fracture network (3D-DFN) and then according to the results of the volume distribution of rock blocks, the three frequencies (high-frequency, medium-frequency, and low-frequency) of rockfall events are numerically simulated to obtain the characteristic information of rockfall trajectories. Finally, based on the characteristic information of rockfall trajectories and the GIS platform, the risk of rockfall hazards with three frequencies is evaluated and analyzed. This paper provides a new way for geologists to assess the risk of rockfall hazards and propose reasonable rockfall hazard prevention schemes. [ABSTRACT FROM AUTHOR]

Taiwan, frequently affected by extreme weather causing phenomena such as earthquakes and typhoons, faces a high incidence of rockfall disasters due to its largely mountainous terrain. These disasters have led to numerous casualties, government compensation cases, and significant transportation safety impacts. According to the National Science and Technology Center for Disaster Reduction records from 2010 to 2022, 421 out of 866 soil and rock disasters occurred in eastern Taiwan, causing traffic disruptions due to rockfalls. Since traditional sensors of disaster detectors only record changes after a rockfall, there is no system in place to detect rockfalls as they occur. To combat this, a rockfall detection and tracking system using deep learning and image processing technology was developed. This system includes a real-time image tracking and recognition system that integrates YOLO and image processing technology. It was trained on a self-collected dataset of 2490 high-resolution RGB images. The system's performance was evaluated on 30 videos featuring various rockfall scenarios. It achieved a mean Average Precision (mAP50) of 0.845 and mAP50-95 of 0.41, with a processing time of 125 ms. Tested on advanced hardware, the system proves effective in quickly tracking and identifying hazardous rockfalls, offering a significant advancement in disaster management and prevention. [ABSTRACT FROM AUTHOR]

The determination of the so-called design block is one of the central elements of the Austrian guideline for rockfall protection ONR 24810. It is specified as a certain percentile (P95–P98, depending on the event frequency) of a recorded block size distribution. Block size distributions may be determined from the detachment area (in situ block size distribution) and/or from the deposition area (rockfall block size distribution). Deposition areas, if present, are generally accessible and measurable without technical aids. However, most measuring methods are subjective, uncertain, not verifiable, or inaccurate. Also, rockfall blocks are often fragmented due to the preceding fall process. The in situ block size distribution is (also) required for meaningful rockfall modelling. The statistical method seems to be the most efficient and cost-effective method to determine in situ block size distributions with many blocks within the whole range of block sizes. In the current literature, joint properties are often described by the lognormal and exponential distribution functions. Today, we can model synthetic rock masses on the basis of discrete fracture networks. They statistically describe the geometric properties of the joint sets. This way, we can carry out exact rock mass block surveys and determine in situ block size distributions. We wanted to know whether the in situ block size distributions derived from the synthetic rock mass models can be described by probability distribution functions, and if so, how well. We fitted various distribution functions to three determined in situ block size distributions of different lithologies. We compared their correlations using the Kolmogorov–Smirnov test and the mean-squared error method. We show that the generalized exponential distribution function best describes the in situ block size distributions across various lithologies compared to 78 other distribution functions. This could lead to more certain, accurate, verifiable, holistic, and objective results. Further investigations are required. [ABSTRACT FROM AUTHOR]

Cases of rockfalls that occurred on a slope in the Selendi District of Manisa Province are evaluated in this article. Field studies are evaluated and different measures are examined to reduce rockfall risk. Drone flights are used to evaluate previous studies and obtain 1/1000 scale digital topographic maps. These maps are used to create a 3D (three-dimensional) solid model of the project site, and on-site surveys are conducted to identify source rock locations and free blocks that pose a risk. Those 3D analyses are used to determine the paths, jump heights, and energies of the blocks in motion. The data from the 3D maps are used to determine the most appropriate remediation methods. The structural behavior of the recommended gabion wall, which is designed at a certain height and width as a result of rockfalls, has been examined. Structural behavior is determined by simulation based on the finite element model. Within the scope of this study, the ANSYS Workbench program is used. The "Explicit Dynamics" analysis type in ANSYS Workbench was chosen to examine the rockfall effect. [ABSTRACT FROM AUTHOR]

Rockfalls are major geological hazards threatening prestressed concrete cylinder pipes (PCCPs) in water diversion projects. To accurately assess the impact of large deformation movements of rockfalls on PCCPs, this study utilized the continuous–discontinuous method to investigate the dynamic response of a PCCP under a rockfall. The impact mode of rockfalls, the mechanical characteristics of PCCP, and the nonlinear-contact characteristics between soil and PCCP were considered in this study. The advantages of continuous and discontinuous numerical simulation methods were utilized to establish a continuous and discontinuous coupling model of "tube-soil-rock" considering the interaction of soil and structure. The impact mechanism and process of PCCP under the rockfall were investigated by simulating the rockfall process and analyzing its spatiotemporal evolution. The influence of PCCP under rockfalls with different heights and radii was studied to clarify the effects of these two parameters on the PCCP. Combined with a practical application example of large-scale water transfer projects, there is a tendency of center flattening under static load and dynamic impact load, and the PCCP part directly below the impact point is the most dangerous. This investigation provided a comprehensive understanding of the impact mechanism of the PCCPs under rockfall. The findings of this study have significant implications for the design of the protection engineering of PCCPs and ensuring the safe operation of water diversion projects. [ABSTRACT FROM AUTHOR]

Rockfall and rock avalanches are common in steep terrain on Earth and potentially on other planetary bodies such as the Moon and Mars. Since impacting rocks can damage exposed bedrock as they roll and bounce downhill, rockfall might be an important erosive agent in steep landscapes, even in the absence of water. We developed a new theory for rockfall‐driven bedrock abrasion using the ballistic trajectories of rocks transported under gravity. We calibrated this theory using laboratory experiments of rockfall over an inclined bedrock simulant. Both the experiments and the model demonstrate that bedrock hillslopes can be abraded by dry rockfall, even at gradients below the angle of repose, depending on the bedrock roughness. Feedback between abrasion and topographic steering of rockfall can produce channel‐like forms, such as bedrock chutes, in the absence of water. Particle size has a dominant influence on abrasion rates and runout distances, while the hillslope angle has a comparatively minor influence. Rockfall transport is sensitive to bedrock roughness; terrain with high friction angles can trap rocks creating patches of rock cover that affect subsequent rockfall pathways. Our results suggest that dry rockfall can play an important role in eroding and channelizing steep, rocky terrain on Earth and other planets, such as crater degradation on the Moon and Mars. Plain Language Summary: Rockfall is common on Earth and other planets. Falling rocks bounce down rocky slopes and likely also erode them. However, it has not been explored how erosive this process is, nor what landforms it might generate. We developed a numerical model for this erosion process and calibrated it with experiments of dry grains hopping down an inclined erodible surface. Both experiments and modeling showed that bedrock erosion from rockfall can occur even on relatively low‐grade hills. Small hollows were carved by rockfall, which over time coalesced into larger troughs that captured the path of subsequent rocks. This process led to a self‐enhancing feedback that produced a bumpy surface with rocky chutes. Rock size had a larger effect on erosion amounts than the steepness of the hill. Our work suggests that dry rockfall can play an important role in the evolution of mountain slopes on Earth and craters on the Moon and other planets. Key Points: Rockfall can erode rocky hillslopes even below the angle of reposeGrain size has a dominant effect on impact abrasion; slope is of minor importanceTopographic steering of grain results in self‐formed bedrock channels [ABSTRACT FROM AUTHOR]

Combined with the current situation of the slope rockfall disaster, the influences of factors such as falling stone quality, falling height, cushion thickness, reinforcement position, reinforcement material and other factors on the impact force of falling rocks and their dynamic evolution are systematically analyzed based on the falling stone model test, the dynamic response law of falling rockfall impact shed caves is revealed, and the optimal thickness of the cushion layer is determined by combining the double factors of the self-weight of the cushion and the impact of falling rocks. Theoptimization suggestions for the design of the cushion are proposed. The results show that with the increase of the thickness of the cushion, the impact force of the falling rock affected by the shed hole decreases non-linearly, and the reduction amplitude is first large and then small, and tends to be stabilized. Under the same cushion thickness, the impact force of falling rocks affected by the shed cave increases linearly with the height of falling stones and the weight of falling stones. When the composite cushion is designed as "5 cm river sand+polystyrene foam (EPS)+10 cm river sand", the peak earth pressure at the center of the falling rock is reduced by about 60% compared with that of the pure river sand cushion, and the buffering energy consumption effect is the best. Through multiple regression analysis, the formula for calculating the impact force of falling rocks is obtained, and the calculation results are well matched with the experimental data. [ABSTRACT FROM AUTHOR]

This paper presents a quantitative methodology for rockfall risk analysis focusing on highway crystalline rock slopes. The proposed method resulted in a risk classification given by a matrix, which relates the rockfall likelihood, with its consequence. The likelihood considers the characteristics of the rock masses and the consequence takes into account the chance of the block reaching the highway and causing accidents. The rockfall likelihood and the consequences are obtained by equations, whose values allow classifying the slopes as high, medium (transition zone), or low rockfall risk. These equations and the matrix of the risk analysis system were generated using linear discriminant analysis and confidence ellipses, both multivariate statistical techniques. Principal component analysis was applied to the dataset before the linear discriminant analysis in order to change qualitative variables into quantitative ones. To establish the classes of failure likelihood and its consequences, cluster analysis was applied. Afterwards, discriminant analysis was applied using the scores of the principal components as independent variables and the resulting clusters as dependent variables. The dataset used in this research has 220 rock slopes and the main variables considered are the parameters traditionally used in hazard and risk classifications for highway slopes. [ABSTRACT FROM AUTHOR]

The article represents a contribution to the assessment of slope processes, with special emphasis on landslides, rockfalls, and creeps along the road sector Batushë-Rrasa e Kosharës (municipality of Gjakova) in Kosova. The analysis of natural factors, as well as their role in triggering and evolving slope processes, was conducted by observing the processes in the field and, with a multidisciplinary approach, analyzing the natural factors (geology, tectonics, climate, vegetation) as well as the role of humans. By using GIS/RS techniques, the causes and features of processes were identified and presented with various illustrations and maps, assessing the potential risk in the future with the aim of proper management, considering the movement of citizens, and preserving the road infrastructure in a segment with historical and touristic values. The slopes with a 35-40° gradient are more prone to landslides, while the presence of unconsolidated rocks and fractured limestone has accelerated slope destabilization and rock mass movements. Slope stability techniques should be implemented in order to keep the road open for future visitors to historical sites. [ABSTRACT FROM AUTHOR]

Gentle dip angle rock slopes are often developed in layered red rocks, which are prone to geological disasters due to the combination of soft and hard lithology. This paper discusses the Tiejiangwan rockfall that occurred on April 5, 2021, in Hongya County of Sichuan province, China, on a layered red rocks slope with a gentle dip angle. Using an air-space-ground integrated earth observation network, including optical remote sensing, UAV aerial photogrammetry, and on-site investigation, the study analyzes the basic characteristics and mechanism of rockfall and predicts the development trend of similar disasters in the steep cliff area of layered red rocks. The results show that the Tiejiangwan rockfall can be divided into two areas, namely the main rockfall area and the rockfall influence area. The main rockfall area comprises one rockfall source area, one shoveling area, one accumulation area, and one water secondary transportation accumulation area. The rockfall influence area includes one potential rockfall source area and five disturbance deformation areas. The rockfall source area has a combination of hard rocks at the top and soft rocks at the bottom, and the rock mass develops two groups of nearly vertical dominant structural planes. In 2013, the source area showed signs of deformation, which eventually lead to the instability of the dangerous rock mass due to the continuous effect of rainfall and temperature differences. The huge impact force caused the rockfall debris flow disaster chain, affecting the old rockfall accumulation body and bedrock under the dangerous rock mass. Optical remote sensing images and field investigation indicate the risk of secondary collapse in Tiejiangwan rockfall. Additionally, six similar potential rockfalls were identified in the adjacent area. To prevent similar disasters, it is recommended to use UAV aerial photogrammetry and airborne LiDAR for early identification and continuous monitoring of potential rockfalls in the steep cliff area of the Tiejianwan. The findings of this study provide valuable data support for the study of similar disasters in layered red rocks.

Block size and shape depend on the state of fracturing of the rock mass and, consequently, on the geometrical features of the discontinuity sets (mainly orientation, spacing, and persistence). The development of non-contact surveying techniques applied to rock mass characterization offers significant advantages in terms of data numerosity, precision, and accuracy, allowing for performing a rigorous statistical analysis of the database. This fact is particularly evident when dealing with rockfall phenomena: uncertainties in spacing and orientation data could significantly amplify the uncertainties connected with in situ block size distribution (IBSD), which represents a relation between each possible value of the volume and its probability of not being exceeded. In addition to volume, block shape can be considered as a derived parameter that suffers from uncertainties. Many attempts to model the possible trajectories of blocks considering their actual shape have been proposed, aiming to reproduce the effect on motion. The authors proposed analytical equations for calculating the expected value and variance of volume distributions, based on the geometrically correct equation for block volume in the case of three discontinuity sets. They quantify and discuss the effect of both volume and shape variability through a synthetic case study. Firstly, a fictitious rock mass with three discontinuity sets is assumed as the source of rockfall. The IBSDs obtained considering different spacing datasets are quantitatively compared, and the overall uncertainty effect is assessed, proving the correctness of the proposed equations. Then, block shape distributions are obtained and compared, confirming the variability of shapes within the same IBSD. Finally, a comparison between trajectory simulations on the synthetic slope is reported, aiming to highlight the effects of the propagation of uncertainties to block volume and shape estimation. The benefits of an approach that can quantify the uncertainties are discussed from the perspective of improving the reliability of simulations.