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Due to climate change and earthquakes, cascading geological hazards frequently occur in the southeastern Tibetan Plateau. However, the region's inaccessibility has limited the recording and monitoring of such events. The Sedongpu catchment is among the most active in the area, with over ten rock avalanche-debris flow events since 2017. On September 28, 2023, a significant rock avalanche-debris flow in the Sedongpu catchment blocked the Yarlung Tsangpo River for approximately 8 h, raising the water level by over 15 m upstream. This study integrates remote sensing, unmanned aerial vehicle (UAV) images, video footage, seismic signals, and meteorological data to analyze the cascading hazard. We found that the primary cause of the event was a high-altitude rock avalanche impacting pre-existing saturated loose material from a previous rock avalanche, converting into a debris flow. The volume of the rock avalanches was estimated to be ~ 95 Mm3, with ~ 13.5 Mm3 deposited in the channel. Debris temporarily dammed the river, and most of them were subsequently washed away. This is the first documented observation of cascading hazards in the Sedongpu catchment, providing insights into the mechanisms of cascading rock avalanches in alpine regions, informing early warning systems, and supporting future hazard prediction and management. [ABSTRACT FROM AUTHOR]

Large rock avalanches play a key role in shaping alpine landscapes. However, the complex interplay between mass movement and other surface processes poses challenges in identifying these deposits and understanding the underlying process controls. Here, we focus on the rock avalanche deposit of the Lurnigalp valley in the Bernese Alps (Switzerland), originally mapped as till. The Lurnigalp valley is a U-shaped tributary valley located in the southwest of Adelboden, Canton Bern. To explore the timing and dynamics of the rock avalanche event, we employed detailed remote and field mapping, sedimentary petrology, surface exposure dating with cosmogenic 36Cl, and runout modelling with DAN3D®. For the reconstruction of the chronology, we analyzed cosmogenic 36Cl in surface samples from 15 boulders of the rock avalanche deposit. We developed three distinct scenarios to investigate the dynamics and contextual conditions of the rock avalanche event. In the first scenario, we consider a rock avalanche depositing 1 Mm3 of sediment in a valley devoid of ice. The second scenario uses the same deposit volume but introduces a hypothetical glacier occupying the uppermost part of the valley. Finally, the third scenario, similar to the first scenario with a glacier-free valley, assumes a substantially larger volume of collapsed rock mass. We consider the third scenario the most plausible, in which approximately 6 Mm3 of rock mass, composed of limestone and sandstone, was released from a limestone cliff around 12 ± 2 ka during the Younger Dryas. The collapsed rock mass fell into the ice-free valley floor, ran up the opposite valley side and was deflected towards the northeast following the valley orientation. The rock mass stopped after 2.2 km leaving approximately 6.4 Mm3 deposits spread across the entire valley floor. Subsequently, most of the rock avalanche deposit have been reworked by periglacial activity. We suggest that structural features, lithology and glacial erosion and debuttressing were involved in the weakening of the in-situ bedrock that finally led to the collapse. Our study not only enhances the understanding of rock avalanche mechanisms and their profound impact on Alpine landscape evolution but also elucidates the complex interplay of geological processes that led to the collapse and altered the rock avalanche deposit afterwards. [ABSTRACT FROM AUTHOR]

The “8·8” Jiuzhaigou Ms7.0 earthquake in 2017 triggered a large number of rock avalanches and landslide geological disasters in the Jiuzhaigou scenic area, accompanied by a large number of potential rock avalanches, which seriously threatened the normal operation of the scenic area. Therefore, accurate prediction of the movement trajectory of rockfalls after the potential rock avalanche collapses is the premise and basis of engineering treatment and protection design. Thus, based on the overview and analysis of the current methods for predicting the movement trajectory of rockfalls, it is assumed that the current theoretical and numerical methods usually take the rockfall collision recovery coefficient as a constant, without properly considering the impact of rockfall motion parameters, such as incident angle and incident velocity, and the yield strength of slope rock and soil on the rockfall collision recovery coefficient. In view of this problem, based on previous studies, a theoretical model for calculating the movement trajectory of rockfalls considering the above two factors is proposed. Finally, it is adopted to predict the movement trajectory of the rockfall located on the upper slope of the northwest side of Huohuahai-Shuzhengzhai Road in Jiuzhaigou scenic area. The calculation results show that when one rock avalanche induced by another earthquake, the rockfall will move along the slope with its maximum horizontal motion distance reaching 639.8 m and 29.1 m along the horizontal toe of slope section. It indicates that the rockfall will pose a serious threat to road traffic safety, and the rockfall protection structure must be set up at the appropriate position of the slope to ensure road traffic safety. Meanwhile the Rocfall software is adopted to validate the calculation results obtained with the proposed method, which indicates the validity of the proposed method. [ABSTRACT FROM AUTHOR]

Rock avalanches in fjord environments can cause direct catastrophic damage and trigger secondary submarine landslides and tsunamis. These are well-documented in Greenland, Norway, and Alaska but have gone largely unreported in the extensive fjord terrain of the eastern Canadian Arctic. We provide the first inventory of rock avalanche deposits in northeastern Baffin Island—a region characterized by moderate to high seismic hazard, steep and high-walled fjords and glacial valleys, active deglaciation, and observed climate warming. Over a broad study area of ~60,000 km2, one sixth of the terrain had sufficient slope height and gradient to potentially generate rock avalanches. Within that hazard zone, we identified eight rock avalanche deposits at six locations. Only three rock avalanche deposits at two locations are dated, using aerial imagery (1958-present), to the last century while five deposits at four locations are inferred as syn- to post-glacial, likely occurring shortly after local debuttressing. These total numbers fall well below documented inventories from Greenland, Norway, and Alaska. We hypothesize that (1) continuous permafrost persists throughout this region and continues to act as a stabilizing factor and (2) rock mass quality is high in areas of most extreme relief contrast within the study region relative to analogous high-latitude fjord systems such as those in southwestern Greenland. We suggest that Baffin Island is currently in a period of quasi-stability that follows the intense instability during initial deglaciation, yet precedes the higher anticipated slope instability that may occur during permafrost degradation. [ABSTRACT FROM AUTHOR]

We explore the viability of modeling dynamic problems with a new formulation of an impulse‐based Level‐Set DEM (LS‐DEM). The new formulation is stable, fast, and energy conservative. However, it can be numerically stiff when the assembly has substantial mass differences between particles. We also demonstrate the feasibility of modeling deformable structures in a rigid body framework and propose several enhancements to improve the convergence of collision resolution, including a hybrid time integration scheme to separately handle at rest contacts and dynamic collisions. Finally, we extend the impulse‐based LS‐DEM to include arbitrarily shaped topographic surfaces and exploit its algorithmic advantages to demonstrate the feasibility of modeling realistic behavior of granular flows. The new formulation significantly improves the performance of dynamic simulations by allowing larger time steps, which is advantageous for observing the full development of physical phenomena such as rock avalanches, which we present as an illustrative example. [ABSTRACT FROM AUTHOR]

The bidispersity observed in the particle‐size distribution of rock avalanches and volcanic debris avalanches (rock/debris avalanches) has been proposed as a factor contributing to their long runout. This has been supported by small‐scale analog experimental studies, which observe that a small proportion of fine particles mixed with coarser particles enhances granular avalanche runout. However, the mechanisms enabling this phenomenon and their resemblance to rock/debris avalanches have not been directly evaluated. Here, binary mixture granular avalanche experiments are employed to constrain the processes and conditions under which bidispersity enhances the runout of granular avalanches in experiments. Structure‐from‐motion photogrammetry is used to measure center of mass displacement and assess energy dissipation. Subsequently, this study evaluates the dynamic scaling and flow regimes in the lab and field to assess whether the runout‐enhancing mechanism is applicable to rock/debris avalanches. In small‐scale experiments, the granular mass propagates under a collisional regime, enabling kinetic sieving and size segregation. Fine particles migrate to the base where they reduce frictional areas between coarse particles and the substrate and encourage rolling. The reduced energy dissipation increases the kinetic energy conversion and avalanche mobility. However, rock/debris avalanches are unlikely to acquire a purely collisional regime; instead, they propagate under a frictional regime. The size segregation which is essential for the process observed at the lab‐scale is prohibited by the frictional regime, as evident by the sedimentology of rock/debris avalanche deposits. The proposal of bidispersity as a runout‐enhancing mechanism overlooks that scale‐dependent behaviors of natural events are often omitted in small‐scale experiments. Plain Language Summary: Large landslides such as rock avalanches and volcanic debris avalanches flow unexpectedly long distances before stopping. The mechanisms generating this phenomenon remain unknown. The fact that they contain large proportions of finer and coarser particles (with relatively smaller quantities of the sizes between them) has been suggested by experiments to be a potential factor for the long distances they cover. In this work, we have carried out experiments to examine the processes enabling this event at the scale of lab experiments in order to assess their potential in real events. We found that this phenomenon is caused by fine particles percolating to the base of the flow. There, they reduce the surface of the coarse particles, which are in contact with the substrate, and also encourage the rolling of the coarser particles. This reduces frictional energy loss, and conserves more energy, which contributes to the flow, leading to longer distances. However, the conditions which allow these processes and the percolation of the fine particles to the base are scale‐dependent and are not applicable to large‐scale events. When planning granular flow experiments or interpreting their findings, scaling is important to ensure similarity between the experimental conditions and the physical processes targeted. Key Points: For bidispersity to enhance the runout of analog granular avalanches, a collisional regime and particle segregation are requiredDynamic scaling suggests that processes and flow regimes reducing apparent friction in small analog experiments are scale‐dependentLack of signature of agitation and size segregation reported in large field‐scale avalanche sedimentology suggests dissimilar processes [ABSTRACT FROM AUTHOR]

Fragmentation is a common phenomenon in complex rock‐avalanches. The fragmentation intensity and process determines exceptional spreading of such mass movements. However, studies focusing on the simulation of fragmentation are still limited and no operational dynamic simulation model of fragmentation has been proposed yet. By enhancing the mechanically controlled landslide deformation model (Pudasaini & Mergili, 2024, https://doi.org/10.1029/2023jf007466), we propose a novel, unified dynamic simulation method for rock‐avalanche fragmentation. The model includes three important aspects: mechanically controlled rock mass deformation, momentum loss while the rock mass fiercely impacts the ground, and the energy transfer during fragmentation resulting in the generation of dispersive lateral pressure. We reveal that the dynamic fragmentation, resulting from the overcoming of the tensile strength by the impact on the ground, leads to enhanced spreading, thinning, run‐out and hypermobility of rock‐avalanches. Thereby, the elastic strain energy release caused by fragmentation becomes an important process. Energy conversion between the front and rear parts caused by the fragmentation results in the enhanced forward movement of the front and hindered motion of the rear of the rock‐avalanche. The new model describes this by amplifying the lateral pressure gradient in the opposite direction: enhanced for the frontal particles and reduced for the rear particles after the fragmentation. The main principle is the switching between the compressional stress and the tensile stress, and therefore from the controlled deformation to substantial spreading of the frontal part in the flow direction while backward stretching of the rear part of the rock mass. Laboratory experiments and field events support our simulation results. Plain Language Summary: Rock‐avalanches often fragment into pieces when they slide down mountain slopes. Fragmentation converts the rock mass into a deformable granular avalanche. This leads to high‐velocity fragments, resulting in more extensive lateral spreading of rock particles. However, no operational dynamic simulation model exists to describe rock fragmentation and the subsequent granular avalanche. Here, we introduce a simple model for the simulation of rock‐avalanche fragmentation dynamics that unifies important processes of mechanically controlled deformation, momentum loss as the rock mass impacts the ground, fragmentation, energy conversion among fragmented clasts and the induced dispersive pressure. The model is capable of automatically simulating rock mass movements as rigid blocks, the fragmentation of these blocks into granular avalanches, and the deposition process. This explains many important phenomena observed in fragmenting rock‐avalanches, including the exceptional lateral spreading, thinning, and hypermobility in the run‐out zone. We implement this model in the freely available computer simulation program r.avaflow, and present some tests on simple computer‐generated landscapes to demonstrate that the model works well. Key Points: We propose a novel, unified dynamic simulation method for rock‐avalanche fragmentation and propagationIt includes mechanically controlled rock deformation, momentum loss at impact and energy transfer in fragmentation generating lateral pressureDynamic fragmentation resulting from overcoming of tensile strength leads to enhanced spreading, thinning, and hypermobility of rock‐avalanches [ABSTRACT FROM AUTHOR]

Mobility of long-runout catastrophic landslides (debris flows, debris and rock avalanches) can be characterized by several parameters. Those, allowing predicting exposure of elements at risk that might be threatened by such hazardous natural phenomena if they will occur—the affected area and runout, are most important for risk assessment. They can be estimated using two general approaches—one based on the numerical modeling and another one based on the empirical relationships between runout and affected area on the one hand and parameters characterizing the potential source zone on the other hand. The latter are volume of the anticipated rock slope failure and height of the unstable slope. Both can be assessed prior to failure with certain accuracy by contrast with the height drop defined as the elevation difference between headscarp crown and the deposit tip. The optimal input parameter is the product of the unstable slope height and possible failure volume that is, in general, proportional to the potential energy of the unstable rock massif. According to the analysis of the Central Asian rockslides/rock avalanches database that includes quantitative parameters of 515 case studies with defined confinement, the relationships of such product with runout and affected area have high correlation coefficients regardless of the confinement conditions and, therefore, allow prediction of the parameters in question with sufficient reliability. It is pointed out that requirements to the accuracy of slope height and failure volume assessment depend on a large extent on the variability range of these parameters within the inventories used to derive the empirical relationships. [ABSTRACT FROM AUTHOR]

Although numerous recent studies have explored the relationship between permafrost degradation and rock slope failure, there is still a need for in‐depth investigations to develop relevant hazard assessment approaches. We investigate the predisposing, triggering and propagation processes of a rock avalanche (c. 225,000 m3) that occurred in Vallon d'Étache (France) on 18 June 2020, whose scar was coated by ice and water. Weather records and energy balance models show that the rock avalanche occurred right after the warmest spring and winter since at least 1985, but also right after the spring with the highest water supply anomaly (snowmelt and rainfall). Measured ground surface temperature and geoelectrical surveys reveal that relatively ice‐rich permafrost could exist in the NW face (release area) while it is inexistent below the SE face, contradicting certain permafrost maps. Heat transfer simulations suggest that the rock avalanche occurred during a transition from cold to warm permafrost conditions at failure depth (30 m), with a temperature increase of up to 0.6°C per decade since 2012 (when considering potential snow cover effect), and current temperature ranging between −3 and −1°C, depending on the applied model forcing. This warming certainly contributed to predispose slope to failure. In addition, the shift towards warm permafrost and water infiltration potentially enhancing permafrost degradation along fractures through heat advection or favouring the development of high hydrostatic pressures may have played as triggering factors. Finally, propagation simulations show that the rock avalanche involved several phases with different rheological properties due to the incorporation of snow and material segregation within the deposit. These new insights at various scales highlight the complexity of the triggering and propagation processes of rock slope failure occurring in high mountains, a significant part of which can be linked to snow effects on ground temperature, water supply and rheological properties. [ABSTRACT FROM AUTHOR]

In recent years, rock avalanche disasters have been occurring frequently in southwest China, which seriously affect the regional ecological environment and human activities. To understand the fragmentation characteristics of the avalanche masses during their movement, this study is based on the field investigation of the rock avalanche in Zongling Town, Nayong County. The dynamic fragmentation process of the rock avalanche during the failure and accumulation stages was simulated using the particle discrete element method. Additionally, the distribution characteristics of the maximum feret’s diameter of the fragments within the rock avalanche mass were statistically analyzed. The results show that: (1) Under the effect of gravity, the internal structural joints of the rock avalanche rapidly interconnected, dividing the avalanche mass into numerous fragmented blocks that eventually slid along the down-dip joint surfaces. (2) The collapse exhibited significant fragmentation phenomena in the entire movement process, with extensive disintegration during the initial failure and friction-induced tearing and cracking fragmentation during the accumulation stage. (3) The feret’s diameter distribution curves of the fragments at different time intervals were fitted using Weibull two-parameter distribution model and fractal geometry theory. The results showed that the fragmentation degree of the avalanche during the accumulation stage (t = 21.7 to 72.4 s) was weaker than that during the initial failure stage (t = 0 to 21.7 s). The fractal dimension of the fragments and the proportion of fine-grained fragments continuously increased throughout the entire movement process, once again confirming the fragmentation and disintegration phenomena during the entire process of failure and accumulation. The research findings provide a theoretical basis for revealing the dynamic fragmentation mechanism of the Zongling rock avalanche, and provide scientific guidance for the prevention and control of rock avalanche disasters in the mountainous areas of southwest China.

Rock avalanches typically entail the flow-like motion of angular rock blocks and fragments of diverse size. Numerical simulations are instrumental in understanding their dynamic process, supporting hazard and risk assessments. Simplified failure criteria, such as the Mohr-Coulomb or Drucker-Prager, are commonly adopted in landslide models relying on the material point method (MPM). However, these criteria cannot capture the transitions between solid-like, liquid-like, and gas-like behaviors exhibited by granular materials. Here, we relied on the moving least-squares MPM, which offers high computing efficiency and stability, and adopted a nonlocal μ(I) rheology model implemented by Haeri and Skonieczny (Comput Methods Appl Mech Eng, 2022). This approach can account for the rate-dependent, pressure-dependent, and size-dependent characteristics of friction in granular materials. By simulating a small-scale flume experiment as well as a large-scale event (the Nayong rock avalanche in Guizhou, China), we verified that the nonlocal μ(I) rheology model can capture the motion and deposition processes in rock avalanches effectively. This feature can be advantageous in physically based hazard assessments of such events. [ABSTRACT FROM AUTHOR]

In recent years, rock avalanche disasters have been occurring frequently in southwest China, which seriously affect the regional ecological environment and human activities. To understand the fragmentation characteristics of the avalanche masses during their movement, this study is based on the field investigation of the rock avalanche in Zongling Town, Nayong County. The dynamic fragmentation process of the rock avalanche during the failure and accumulation stages was simulated using the particle discrete element method. Additionally, the distribution characteristics of the maximum feret's diameter of the fragments within the rock avalanche mass were statistically analyzed. The results show that: (1) Under the effect of gravity, the internal structural joints of the rock avalanche rapidly interconnected, dividing the avalanche mass into numerous fragmented blocks that eventually slid along the down-dip joint surfaces. (2) The collapse exhibited significant fragmentation phenomena in the entire movement process, with extensive disintegration during the initial failure and friction-induced tearing and cracking fragmentation during the accumulation stage. (3) The feret's diameter distribution curves of the fragments at different time intervals were fitted using Weibull two-parameter distribution model and fractal geometry theory. The results showed that the fragmentation degree of the avalanche during the accumulation stage (t = 21.7 to 72.4 s) was weaker than that during the initial failure stage (t = 0 to 21.7 s). The fractal dimension of the fragments and the proportion of fine-grained fragments continuously increased throughout the entire movement process, once again confirming the fragmentation and disintegration phenomena during the entire process of failure and accumulation. The research findings provide a theoretical basis for revealing the dynamic fragmentation mechanism of the Zongling rock avalanche, and provide scientific guidance for the prevention and control of rock avalanche disasters in the mountainous areas of southwest China. [ABSTRACT FROM AUTHOR]

We investigated the paraglacial evolution and permafrost degradation of Val Viola (Upper Valtellina, Central Italian Alps) through a geomorphologic survey, cosmogenic dating, Schmidt's Hammer, and surface roughness measurements. Our results reveal that the previously mapped Val Viola rock avalanche is probably derived by three different events that occurred 7.7 ± 0.2 ka (Orthogneiss_ 1), 7.0 ± 0.2 ka (Paragneiss), and 5.0 ± 0.3 ka (Orthogneiss_2). Because the main valley bottom has been ice free since at least 12.6 ka, it is unlikely that the triggering factor of these events was the debutressing stress caused by the melting of local valley glaciers. Therefore, permafrost that formed in this area down to 2525 m a.s.l. at 9.3–8 ka and degraded successively between 7.8 and 6.5 ka was likely the main triggering factor of the first two rock avalanche events, as well as for the third event that happened during the warm and wet period of the Holocene Thermal Maximum around 5 ka. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering Geology / Gongcheng Dizhi Xuebao is the property of Journal of Engineering Geology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Engineering Geology / Gongcheng Dizhi Xuebao is the property of Journal of Engineering Geology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Long-runout rockslides at high altitude have caused lots of severe casualties and huge economic losses in the world, becoming a focus issue in researches on mitigation for large-scale geological disasters. This paper systematically reviews the research process of high-altitude and long-runout rockslides and believes that conventional research on “high velocity and long runout” is difficult to adapt to the requirements of complex geohazards prevention and mitigation in high and extra-high mountains. The methodology on high-altitude and long-runout rockslides has been proposed that includes in the initiation at the high-position, the dynamics of chain-style disasters with a long-runout traveling and the risk assessment and mitigation. Then, the disaster-prone geostructure characteristics and early identification techniques of the high-altitude initiation zone, the long-runout transferring mechanism and boundary layer effect of high-velocity debris avalanche, and risk assessment and mitigation issues have been explored. Through the study in the high mountain and extra-high mountains of the Qinghai-Tibet Plateau indicates that the potential flow transferring mechanism of debris avalanche in high-altitude rockslides, the boundary layer effect of turbulent fluid and the plowing bodies. It is proposed that energy dissipation and risk mitigation methods can be used by modifying the boundary layer bottom slope of high potential debris avalanche, to increase the generation of turbulent kinetic energy in the boundary layer, and the dead zone range in front of barrier piles. Three research directions have been discussed, including the initiating mechanism of disaster-prone geostructure, the dynamic process of high-altitude and long-runout disaster chains, and the theory and technology of risk prevention and mitigation.

Mountainous regions present severe risks, including damage to transportation infrastructure, due to the occurrence of geohazards such as rock avalanches and other types of landslides. Lessons learned from past damaging events are helpful for risk reduction in mountainous regions. In this paper, to study a rock avalanche impact on a bridge, a numerical modeling framework with the aid of the discrete element method (DEM) is developed; the progressive failure process of an expressway bridge that was damaged by a rock avalanche is reproduced, and the failure mechanisms and dynamic behaviors of the bridge under impact are assessed. The Yaxi Expressway bridge that was destroyed by the September 20, 2020, Yaoheba rock avalanche in southwest China is used as an illustrative example. A field investigation is carried out to identify geological conditions, characteristics, and the kinetic failure pattern of the rock avalanche and the bridge. The stereographic projection analyses indicate that this rock avalanche was initiated as a planar slide. A three-dimensional numerical model of the rock avalanche and bridge is developed based on the terrain data acquired. The critical parameters of the numerical model are calibrated based on results obtained from laboratory tests. Finally, the progressive failure process and failure mechanism of the impacted bridge are analyzed based on the constructed numerical model. The comprehensive analysis framework can be applied to similar events involving geohazard-structure interaction. [ABSTRACT FROM AUTHOR]

Rock avalanches are generally difficult to prevent and control due to their high velocities and the extensive destruction they cause. However, barrier structures constructed along the path of a rock avalanche can partially mitigate the magnitudes and consequences of such catastrophic events. We selected a rock avalanche in Nayong County, Guizhou Province, China as a case to study the effect of the location and height of a retaining wall on the dynamic characteristics of rock avalanche by using both actual terrain-based laboratory-model tests and coupled PFC3D–FLAC3D numerical simulations. Our findings demonstrate that a retaining wall can largely block a rock avalanche and its protective efficacy is significantly influenced by the integrity of the retaining wall. Coupled numerical simulation can serve as a powerful tool for analyzing the interaction between a rock avalanche and a retaining wall, facilitating precise observations of its deformation and destruction. The impact-curve characteristics of the retaining wall depend upon whether or not the rock avalanche-induced destruction is taken into account. The location of the retaining wall exerts a greater influence on the outcome compared to the height and materials of the retaining wall, while implementing a stepped retaining-wall pattern in accordance with the terrain demonstrates optimal efficacy in controlling rock avalanche. [ABSTRACT FROM AUTHOR]

Geomorphological and sedimentological characteristics are key evidences for understanding the emplacement mechanisms of rock avalanches. Based on remote sensing, photogrammetry, and field surveys, the depositional characteristics of the Alasu rock avalanche (ARA) in southern Tianshan, China, were investigated in detail. It is reached that the ARA has a detached rock mass volume of ~ 93 × 106 m3 and propagated 3874 m on rugged terrain with a drop height of 1030 m. Large rock blocks (95,598 rock blocks with sizes ≥ 0.5 m) are widely distributed on the deposit surface. There is no decreasing trend in block size with travel distance for these rock blocks, while jigsaw and sibling structures of megablocks commonly occur in the carapace facies. The size and structural features of megablocks demonstrate that the carapace facies underwent a passive emplacement process with low degrees of fragmentation and disturbance. Furthermore, a series of surficial landforms, including irregular platforms, minor scarps, lateral levees, run-ups, ridges, and troughs, are preserved in the rock avalanche deposit. The most remarkable features are the large, subparallel, curved longitudinal ridges with continuous directional variations and three run-up traces. Extensions of these ridges indicate that the avalanche mass experienced a continuous extension-dominated process in emplacement due to its momentum transfer effect and high energy propagation. These observations and analyses may elucidate the emplacement mechanisms of rock avalanches in rugged landscapes. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Geological Hazard & Control is the property of China Institute of Geological Environmental Monitoring (CIGEM) Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Introduction The rock avalanches are a frequent and disruptive phenomenon in the Himalayas and other mountain chains. To minimize future losses, it is essential to investigate the engineering geological causative factors and mechanism of these mass wasting events. Study area The present work is aimed at assessing the failure mechanism of the disastrous 2014 Jure rock avalanche along Araniko Highway, Northern Nepal. The event had blocked the Sunkoshi River and blocked an economically significant route to China. Geotechnical properties and analysis Initially, rockmass characterization and intact strength attribute were determined for the site to classify the failure zone. The parameters measured and obtained from the field and laboratory were integrated into the analytical models to obtain a conclusive interpretation of the failure mechanism. Structural, kinematic, and key block theory analyses have been carried out for decipher the evolution of the failure zone. Results and discussion Rock mass was found to be of fair quality, however, the structural instabilities and the presence of water has led to a progressive failure. Movement of the key block and subsequent sliding of wedges and foot failure appears to be a possible failure mechanism. Conclusion The present research explores the contributory engineering geological aspects of the Jure rock avalanche. The investigation results can be used to tackle similar large scale rock avalanches in similar geological terrains and thus minimizing the losses.

In order to analyze the movement and accumulation characteristics of rock avalanche, a laboratory experiment was set up indoors, and designed with 4 factors, namely, gradation, slope angle, quality of debris flow, and slip surface material, which were used to analyse the effects of each factor on the accumulation characteristics of debris flows. The research results show that the reduced slope angle and rougher slip surface caused some of the particles to accumulate or be retained on the slope surface, and that there were differences in the characteristics of particle accumulation compared to when the particles were completely accumulated at the bottom of the slope. Slip surface material is basically negatively correlated with accumulation features such as stroke, and slope angle is basically positively correlated with accumulation features, and the two have the greatest influence on accumulation features. The quality of debris flow is basically negatively correlated with accumulation features, and has less influence on the distribution of particles accumulation features. Gradation has no significant correlation with particle accumulation characteristics. [ABSTRACT FROM AUTHOR]

In this study, the 1991 rock avalanche, in Touzhai, Zhaotong, Yunnan, China, was considered the study object. The investigation of the landslide accumulation body revealed that the Touzhai rock avalanche accumulation body has the characteristics of wide gradation and poor sorting. A combination of field investigations, indoor and outdoor experiments, and numerical simulations were used to invert the occurrence and spreading range of rock avalanche-debris flow hazards. To invert and analyze its dynamics and the crushing process, a three-dimensional discrete element modeling was performed on the real terrain data. Simulation results showed that the movement time of the numerically simulated Touzhai rock avalanche was approximately 200 s. After 50 s of movement, the peak velocity reached 32 m/s, and the velocity gradually decayed after the sliding mass rubbed violently against the valley floor and collided with the mountain. Due to the meandering nature of the gully, the sliding mass makes its way down the gully and constantly collides with the mountain, making particles appear to climb, with some particles being blocked by the valley. After 150 s of movement, the average velocity rate decreased substantially, and the landslide-avalanche debris reached the mouth of the trench. After 200 s of movement, the average sliding velocity tends to 0 m/s, where the avalanche debris tends to stop and accumulate. When the rock avalanche movement reaches the mouth of the gully, the avalanche debris spreads to the sides as it is no longer bounded by the hills on either side of the narrow gully, eventually forming a 'trumpet-shaped' accumulation, and the granular flow simulation matched the findings of the landslide site accumulation. [ABSTRACT FROM AUTHOR]

Knowledge of the processes and effects of the block‐grain phase transition in a fragmented system is essential for investigating rock avalanches. Several series of experiments are performed with a very large apparatus, using a jointed block, simulated by an assembly of packed breakable subblocks varying in configuration, as an analog for brittle rock. The analog jointed block is released from a hopper, moves on two inclined flumes with different slopes, and finally deposits on a horizontal platform. The block‐grain phase transition occurs, caused by subblock collisions and explosive impacts with the flume bottom. The dynamic behavior, seismic signal, fragment characteristic, and deposit structure of the analog material are determined. Our results demonstrate that fragmentation influences energy dissipation and momentum transfer, as well as subsequent flow and emplacement processes. A nonunified and piecewise relationship between the fragmentation degree and friction coefficients is observed. We ascribe this nonunified relationship to the varying dynamics and runout regimes that different configurations of jointed blocks undergo. The positive or negative feedback on energy generated by fragmentation is closely associated with the energy budget involved in this fragmented system, which depends substantively on the block configuration. Particularly, for flatter or larger jointed blocks, despite increased fragmentation absorbing the available energy for runout, it simultaneously changes the runout regime toward a more energy‐efficient one, thus instigating positive feedback. Our study further highlights the contribution of post‐fragmentation granular flow to the energy system. Plain Language Summary: Rock avalanches are large highly flow‐like landslides resulting from the sudden failure of rock slopes, which can impact distant areas down stream of their starting zone due to their unexpectedly long runout distances and exceptional mobility. Work by others has identified that block‐grain phase transition due to intense fragmentation is the ubiquitous feature of rock avalanches. However, the processes and implications of this for rock avalanche dynamics have remained vague. In this study, we perform several series of experiments varying in block configuration with a self‐developed apparatus whose large size and complex geometry allow us to more realistically simulate the block‐to‐grain transition. We obtain the data on the dynamic behavior, seismic signal, fragment characteristics, and deposit structure. We further analyze the contact between fragmentation and energy consumption to better understand the role of fragmentation in the energy budget of a rock avalanche system. Key Points: The block‐grain phase transition of a jointed block due to intense fragmentation is investigated with a large‐scale experimental apparatusA nonunified and piecewise relationship between fragmentation intensity and friction coefficients is observedFragmentation consumes energy but can provide positive feedback related to the energy budget relying on the block configuration [ABSTRACT FROM AUTHOR]

Introduction: The rock avalanches are a frequent and disruptive phenomenon in the Himalayas and other mountain chains. To minimize future losses, it is essential to investigate the engineering geological causative factors and mechanism of these mass wasting events. Study area: The present work is aimed at assessing the failure mechanism of the disastrous 2014 Jure rock avalanche along Araniko Highway, Northern Nepal. The event had blocked the Sunkoshi River and blocked an economically significant route to China. Geotechnical properties and analysis: Initially, rockmass characterization and intact strength attribute were determined for the site to classify the failure zone. The parameters measured and obtained from the field and laboratory were integrated into the analytical models to obtain a conclusive interpretation of the failure mechanism. Structural, kinematic, and key block theory analyses have been carried out for decipher the evolution of the failure zone. Results and discussion: Rock mass was found to be of fair quality, however, the structural instabilities and the presence of water has led to a progressive failure. Movement of the key block and subsequent sliding of wedges and foot failure appears to be a possible failure mechanism. Conclusion: The present research explores the contributory engineering geological aspects of the Jure rock avalanche. The investigation results can be used to tackle similar large scale rock avalanches in similar geological terrains and thus minimizing the losses. [ABSTRACT FROM AUTHOR]

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

Trees in forests can obstruct falling rocks and serve as a natural barrier to reduce the velocity of falling rocks. Recently, there has been growing interest in utilizing forests to safeguard against potential rockfall. Nevertheless, there is a dearth of research regarding the impact of rock size and forest structure on forest preservation against rockfall. This study takes the Jiweishan rock avalanche that occurred in China in June 2009 as an example to discuss the protection mechanism of forests against rockfall in rock avalanche disasters. Three sizes of rockfalls from the Jiweishan rock avalanche were simulated and analyzed with and without forests using Rockyfor3D software. The findings indicate that forests can mitigate the energy impact of falling rocks. Especially in the debris flow area of rock avalanches, the protective effect of trees on small-sized falling rocks is most obvious, reducing the runout distance and damage range of the debris flow. Moreover, the protective effect of forest structures on rockfall risk was explored. It was found that broad-leaved forests had the best protection against falling rocks, followed by coniferous broad-leaved mixed forests, and coniferous forests had the worst protective effect. Furthermore, increasing forest planting density and tree diameter at breast height (DBH) can result in better protection against rockfall. Thus, rational planning of forest species and planting density in areas of rockfall can effectively reduce the threat of rockfall risk. The research ideas in this study can provide a basis for evaluating the mitigation of rockfall hazards by forests and provide a reference for constructing and planning protective forests in rockfall and rock avalanche hazard areas. [ABSTRACT FROM AUTHOR]

On 8 May 2022 and 12 April 2020, two large rock avalanches occurred in Zhijin County, China, in the villages of Baiyan and Baiwu, respectively. These long-runout rock avalanches had the same geological, hydrological, and topographical settings and similar triggering factors but different mobility, and this inspired a research interest in the failure and runout processes of large-volume mass movements. In this study, a detailed on-site field investigation was conducted with the aid of unmanned-aerial-vehicle-based photogrammetry and satellite imaging technologies. The results suggest that the two rock avalanches were, rather than a single factor, collaboratively triggered by multiple loading effects involving long-term underground coal-mining vibration, karstification, and cumulative precipitation. The cliff failure was dominated by the strength of the rock mass and development of the joints, while the runout was controlled by the dynamic performance of the soil on the potential sliding surface rather than the rock debris itself. The liquefaction performance of the sliding surface—consisting of coarse soils on an ancient eluvial slope in the transition area—indicates that the Baiyan avalanche had significantly longer runout and higher mobility than the Baiwu case. Although the two avalanches had different mobilities, they both briefly obeyed a physics-based statistical evaluation method—the energy line. [ABSTRACT FROM AUTHOR]

Rock avalanche is a kind of mountain disaster with strong impact and long spreading, which poses a great threat to the safety of life and property and ecological environment in mountain areas. As an effective measure for such disaster reduction, the rationality of the layout of catching dam is of great significance to the mitigation scheme design. Firstly, the influence of the location and height of the catching dam on the deposition characteristics of dry rock avalanche was studied by the means of laboratory model tests. Secondly, the numerical model was established using the three-dimensional particle flow code, and the interaction between granular avalanche and the catching dam was analyzed depending on the calibrated parameters. Finally, a series of three-dimensional numerical simulations were carried out to study the impact force on the catching dam. The results showed that, the position of the catching dam could affect the kinematic process and deposition characteristics obviously, catching dam at the deceleration area can significantly reduce the movement distance, improve the interception efficiency, and reduce the impact range of the rock avalanche. The movement distance, and width and length of the deposition decreased almost linearly with the height of the catching dam. It might be better to arrange the catching dam at the deceleration zone, and the height should be set to about two times the thickness of the accumulation body, which can intercept more than 80% of the debris, and can shorten the movement distance by more than 25%. [ABSTRACT FROM AUTHOR]

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In May 1965, a main landslide occurred in a deeply incised valley of Piton de la Fournaise volcano, in Réunion Island. This event occurred one day after heavy rainfalls and was consequently interpreted as a mud/debris flow. We take advantage of several sets of historical photographs to reappraise this event. They show that the collapse of a large part of the valley headwall produced a rock flow that dropped 1,740 m and traveled 5,050 m. The surface morphology suggests that the landslide produced a main flow that evolved in a secondary flow in the distal part. The main flow deposit is composed of a matrix‐rich fragmented facies and a jigsaw‐fracturated facies. The matrix presents a gravely‐to‐silty granulometry and fractal dimensions ranging between 2.472 and 2.865. Volumes of the collapsed material (59.7 ± 3.1 Mm3) and the deposit (46 ± 13 Mm3) were determined from a photogrammetric approach. We estimated velocities ranging between 86 and 44 m s−1 along the flow path. Our simulations with SHALTOP reveal that the landslide geometry and velocities are well reproduced with frictional Coulomb rheology. We thus interpret the 1965 Mahavel landslide as a main rock avalanche rather than a mud/debris flow. We propose that the trigger of the 1965 avalanche, and of the smaller events in 1995 and 2001, is the water infiltration related to the intense rainfalls, which systematically preceded by one day each collapse. Finally, the succession of dry and wet years before each collapse event could promote favorable conditions to failure. Plain Language Summary: In 1965, a main landslide occurred in a deeply incised valley of Réunion Island (Indian Ocean). It followed heavy rainfalls and was consequently interpreted as a main mudflow. We used historical photographs, deposit descriptions, and numerical simulations to reappraise this event that fortunately did not have any casualties. We show that about 60 Mm3 of volcanic rocks suddenly collapsed and produced a rock avalanche that traveled over a total distance of 5 km. The flow traveled at velocities ranging between 86 and 44 m s−1. We interpret this landslide as a rock avalanche instead of a mudflow. Our work finally suggests that the annual precipitation variability could be a main conditioning factor that promotes scarp collapses and consequently enhances erosion. The increase of precipitation variability with climate warming could therefore increase the occurrence of large collapses and rock avalanches in mountainous areas. Key Points: We use historical photographs, deposit descriptions, and numerical simulations to reappraise the 1965 Mahavel landslide of Réunion IslandThe collapse of 60 Mm3 of volcanic rocks triggered a large rock avalanche that traveled 5 km at velocities as high as 86 and 44 m s−1Rock avalanches are interpreted as the main process to explain the high long‐term erosion rates of Réunion Island [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering Geology / Gongcheng Dizhi Xuebao is the property of Journal of Engineering Geology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper deals with the origin of the Pretare clastic deposit (PRA), which crops out along the Morricone fluvial valley in the Central Apennines of Italy. With the aim of deciphering the genesis of the PRA deposit, geological s.l. and geomorphological analyses were carried out allowing for the interpretation of the PRA deposit as a rock avalanche. Furthermore, geological cross sections constrained by well-log and field survey data, together with stratigraphic, sedimentologic, and morphometric analyses, allowed us to assign the deposit to a catastrophic rock slope failure, which occurred during a cold climate of the Late Pleistocene. Several issues concerning the propagation mechanisms were inferred from the mapping of 350 boulders over the entire accumulation area and from the measure of the morphometric parameters of the landslide body. We also performed a restoration of the potential source area by comparing the reconstructed pre- and post-failure DEMs. A missing volume of 8.41 × 106 m3 was estimated on the south-eastern side of the Vettore Mt., which is consistent with the deposit volume computed from the geological interpretation (10.56 × 106 m3). The outcomes of this study provide useful insights for a better understanding of the Quaternary morpho-evolution of the Central Apennines area where analogous rock avalanche events marked the recent evolution of the belt. [ABSTRACT FROM AUTHOR]

In the comment, Cagnoli (2022, https://doi.org/10.1029/2022JB024799) disagrees with our experimental conclusion that the enhanced particle agitation related to the high magnitude basal fluctuating stresses contributes to the granular flow mobility. Instead, he argues that the slope‐break model used in our experiments prevents the granular flows from being as mobile as they could be. In this reply, we restate our viewpoints by further clarifying the experimental variables and evaluating the effects of the additional phenomena raised in our experiments. By considering the granular flow velocities before the slope‐break, a linear correlation between the depth‐average velocity and equivalent friction coefficient is established, indicating that an increasing flow mobility with decreasing fractal dimension D has already been initiated before the slope‐break. Thus, the slope‐break collision has no significant effect on the general trend of the flow mobility versus grain size and the positive correlation between stress fluctuation and granular flow mobility is still valid. Plain Language Summary: At present, the high mobility of rock avalanches is still an unsolved mystery. Field observations of rock avalanche deposits, as well as the landquakes generated during rock avalanche propagations reveal that a series of physical processes are involved in rock avalanches, some of which should contribute to their high mobility. In our experiments (Li et al., 2022, https://doi.org/10.1029/2021jb022905), a plausible physical process related to rock avalanches was found, that is, the high magnitude fluctuating stresses generated by the interaction between the granular flow and subsurface could contribute to the mobility. However, this finding is questioned by Cagnoli (2022, https://doi.org/10.1029/2022JB024799) because he regards that the slope‐break model used in our study interfered with the reliability of the experimental results. Through further investigation and analysis of the experimental results, it is shown that the granular flow already exhibited a trend of greater mobility with a higher coarse particle content before the slope‐break. This means that the general trends of our experimental results were not changed by the slope‐break collisions and the physical process we found is still justified. Key Points: The enhanced mobility of the granular flow with increasing grain size is initiated before the slope‐break collisionThe generation of high‐magnitude fluctuating stress is the essential physical process promoting granular flow mobility in our studyThe discrepancy between experiments and simulations is attributed to the idealized physics of discrete element method [ABSTRACT FROM AUTHOR]

Anthropogenic climate change is rapidly altering high mountain environments, including changing the frequency, dynamic behavior, location, and magnitude of alpine mass movements. Here, we review three decades of scientific literature (∼ 1995 to early 2024) to assess to what degree observational records from the European Alps – as the region with the most comprehensive records – reveal these changes. We do this for the processes that are most common in this region, namely rockfall, rock avalanches, debris flows, ice avalanches, and snow avalanches. The systematic literature search and review yielded 335 publications, of which we omitted publications that did not focus primarily on observational records. The remaining 103 publications used observations from over 100 sites and 30 inventories to investigate the connection between climate change and mass movements. About one third of the relevant studies found a measurable impact of climate change on the investigated alpine mass movement processes (with the exception of large rock avalanches). The clearest climate-controlled trends are (i) increased rockfall frequency in high-alpine areas due to higher temperatures, (ii) fewer and smaller snow avalanches due to scarcer snow conditions at low and mid elevations, and (iii) a shift towards avalanches with more wet snow and fewer powder clouds. While there is (iv) despite a clear increase in debris-flow triggering precipitation, debris-flow activity has not been found to uniformly increase, though there is some evidence for increasing activity above treeline and at locations without historical precedence. The trends for (v) ice avalanches are spatially very variable with no clear direction. Ice temperatures are measurably increasing, but – despite a theoretical expectation – this has not impacted ice avalanche activity to date. The reviewed literature also reveals that quantifying the impact of climate change on these mass movements remains difficult in part due to the complexities of the natural system, but also because of limitations in the available datasets, confounding effects, and existing statistical processing techniques. Better assessments could be achieved if we would more broadly support the compilation and maintenance of large standardized data catalogs, bring together various dispersed datasets (in said catalogs), including from social and citizen science projects, invest in long-term natural observatories, and develop suitable processing techniques. Better observations will additionally support the development and performance of process-based models. If we can advance natural hazard research on these fronts, more quantitative predictions of future change are well within our reach. [Display omitted] • Impact of climate change on gravitational mass movements in the European Alps: Theory and observations • Overall failure continuum framework for the alpine mass movements • Climate change signal is detectable in observations of all processes but large rock avalanches (> 1 x106 m3) • The complexity of the natural system and data limitations complicate quantifying the impact of climate change [ABSTRACT FROM AUTHOR]

Ubiquitous and complex avalanche–substrate interactions during rock avalanche emplacement have attracted widespread attention in recent years and are regarded as vital processes influencing mobility and damage potential through rapid changes in avalanche mechanical properties. However, the fundamental interaction mechanisms of avalanche mass on substrate and the resultant effect on mobility have yet to be elucidated for natural events. To better understand the mechanics of avalanche–substrate interactions, we present a detailed study on the spectacular synsedimentary deformation structures at the bottom of the gigantic Iymek rock avalanche deposit, including undulose structures, flame structures, mixed textures, clastic dikes, and cracked gravels. The cracked gravels demonstrate that the overriding avalanche mass exited high-energy shearing on the avalanche–substrate interface, where the stress in substrate far exceeded the overburden from the avalanche mass during the avalanche–substrate interaction. Along with high-energy shearing, two different interaction modes with the change of substrate materials are identified, i.e., the Kelvin–Helmholtz instability (KHI) characterized by undulose-to-flame structure transitions, and the Raleigh–Taylor instability (RTI) characterized by the formation of clastic dikes. The KHI is interpreted as a result of the growth of shear instabilities induced by high-energy shearing along the avalanche–substrate interface. The RTI is associated with local liquefaction of the water-bearing sandy substrate and was mainly induced by the high-frequency ground vibrations generated by high-energy shearing. Therefore, we propose that the overriding avalanche mass exited high-energy shearing on the substrate during the avalanche–substrate interaction, which motivated two predominant physical processes of the KHI and RTI along the avalanche–substrate interface. The shear-induced KHI is a potential mechanism of erosion and entrainment in rock avalanches and is responsible for promoting the incorporation of substrate materials into moving avalanche mass. These results not only yield profound insights into the interaction behaviours between rock avalanches and substrates but also provide a fundamental geological prototype to motivate further modelling work to elucidate rock avalanche dynamics. • Spectacular synsedimentary deformation structures are identified in the avalanche deposit. • High-energy shearing acting on avalanche–substrate contact motivated two interface instability. • The Kelvin–Helmholtz instability is induced by shear with an undulose-to-flame structure change. • The Kelvin–Helmholtz instability is the potential mechanisms of erosion and entrainment. • The Raleigh–Taylor instability is associated with local liquefaction induced by shear vibration. [ABSTRACT FROM AUTHOR]

In this paper, we present a numerical study of dynamic behavior of rock avalanche by using three-dimensional particle flow simulation. The emphasis is put on the influence of particle shape, size and gradation on the velocity and energy transformation process of falling rock clusters. A new numerical method is first developed for the three-dimensional reconstruction of rock clusters. A new approach is also proposed for the analysis of falling motion of rock clusters based on different energy transformation processes. A series of numerical calculations are performed with rock clusters composed of particles with different geometrical shapes, sizes and gradation. The influences of these factors on the velocity and energy transformation process are presented and analyzed. The obtained results suggest that the increase in irregularity degree of particle shape of rock clusters reduces the average velocity and collision-induced energy dissipation; for a certain volume of clusters, the decrease in particle size has little effect on the average velocity but significantly enhances friction-related energy dissipation; the impact of gradation is relative complex depending on the combination of shape and size of particles in rock clusters. [ABSTRACT FROM AUTHOR]

Rock avalanches are a significant threat to infrastructure as they can cause catastrophic damage far away from their source. To ensure the safe construction and operation of the Sichuan–Tibet railway in China, there is an urgent need for a comprehensive understanding of the initiation and movement of rock avalanches in the Sichuan–Tibet traffic corrido. The ancient Luanshibao (LSB) rock avalanche that occurred in the SE Tibetan Plateau, had a total volume of more than 64 million m3, a run-out distance of about 4 km, and a low Fahrböschung angle, making it an ideal case for understanding the underlying physical mechanisms of rock avalanches in the region. In this study, the geomorphological features of the initiation and movement of the LSB avalanche were revealed in details, through field investigations, satellite image interpretation, and UAV surveying, thereby obtaining a fault-controlled geomechanical model. The results of laboratory tests confirmed that freeze–thaw weathering created and extended microfractures that exponentially reduced the strength parameters of the rock, resulting in considerable deterioration of the rock mass. The numerical simulations indicated that although strong ground vibrations due to earthquakes were the primary trigger of the avalanche, freeze–thaw weathering and oblique-thrusting of active faulting played important roles, as reflected in the quasi-rotational sliding feature observed on-site and in the simulation. The deposition features observed in the field corresponded to three kinematic regime of rock avalanche experienced. These analyses allowed the proposal of a destabilization model that clarified the different phases leading to the initiation and development of the avalanche. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering Geology / Gongcheng Dizhi Xuebao is the property of Journal of Engineering Geology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)