Rockfall Source Areas Assessment in an Area of the Pollino National Park (Southern Italy)
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Yosemite National Park is a major natural asset of the USA and attracts millions of visitors each year. Its geology and geomorphology make it particularly susceptible to rockfalls, with tens of kilometers of granite cliffs up to 1000 m in height. Between 2010 and 2020, 640 rockfalls were recorded; almost half of these caused damage to the road network somewhere within the park. Approximately 300 rockfalls affected the Merced River corridor, which contains the El Portal Road, the entranceway preferred by about 30% of the visitors. In addition to causing road damage and temporary road closures, rockfalls have also caused fatalities along roadways. Because National Park policies generally preclude mitigations on natural slopes, rockfall risks along roads are mitigated through traffic management practices based on the evaluation of local hazard conditions. Due to the widespread occurrence of rockfalls and the variability of geological conditions, implementing these practices remains challenging and requires a distributed yet accurate quantitative rockfall analysis approach. We performed high-resolution 3D rockfall simulations using the Hy-Stone rockfall runout model over an area about 18 km2 in size that contributes to rockfall hazards along two sections of roadway within the park, including the El Portal Road.We set up our models using existing datasets (1m LiDAR DEM, canopy height, geological and vegetation maps), a database of Yosemite rockfall events (1857-2020), and new field surveys of infrastructure, rockfall paths and deposits, and visible damage caused by previous rockfalls. We identified rockfall sources using a morphometric approach refined by mapping rockfall evidence and additional unstable areas. Sources were classified into “cliff” and “roadcut” (engineered) categories. We mapped Quaternary deposits at the scale of consideration, reclassified vegetation types in categories relevant to rockfall interactions, and produced a unique condition map for model parametrization.We calibrated Hy-Stone parameters (initial velocity, impact restitution, and rolling friction coefficients) by the back analysis of occurred rockfalls, for which field-based evidence was collected by NPS and USGS. We used post-event aerial pictures of the 2017 Parkline rockfall to map the location and size of 4700 blocks, producing a reference block size distribution for the simulations. Model parameters were calibrated by optimizing the fit between simulated and observed arrest locations and volumes.We performed forward simulations over the study area considering “cliff” rockfall sources and two different block volume scenarios: a) realistic, stochastically variable volumes; b) worst-case, constant volume (100 m3). An additional simulation considered roadcut sources with variable block volumes. Results were extracted as raster maps of block frequency, velocity, energy, and height and validated against the historical and field databases, making it possible to perform a quantitative evaluation of rockfall susceptibility using the Rockfall Hazard Vector (RHV) method.Our models combine robust 3D simulations with detailed field data, allowing the characterization of rockfall susceptibility over a large area with the spatial accuracy typical of site-specific studies. This provides robust inputs to quantitative risk analysis that will allow optimizing risk management and granting safer access to the park.
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An overview of traditional and modern engineering systems used rockfall protection is given. The main parameters which are considered in the study of stone-fall processes and in the designing of structures against rockfall are analyzed. Features of the calculation and the global experience of using flexible rockfall barriers are described.
Keywords: rockfall, structures against rockfall, flexible rockfall protection barriers, trajectory of rockfall, impact energy of rock
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Abstract. Rockfalls are an essential geomorphic process and an important natural hazard in steep landscapes across the globe. Seismic monitoring can provide precise information on the timing, location and event anatomy of rockfalls, parameters that are otherwise hard to constrain. By pairing data from 49 seismically detected rockfalls in the Lauterbrunnen Valley, Swiss Alps, with independent information about potential triggers during autumn 2014 and spring 2015, we are able to (i) analyse the evolution of single rockfalls and their common properties, (ii) identify seasonally changing activity hotspots, (iii) and explore temporal activity patterns at different scales, ranging from months to minutes, to quantify relevant trigger mechanisms. Seismic data allows the classification of rockfall activity into three distinct phenomenological types and can be used to discern multiple rock mass releases from the same spot, identify rockfalls that trigger further rockfalls and resolve modes of subsequent talus slope activity. In contrast to findings based on methods with longer integration times, rockfall in the monitored limestone cliff is not spatially uniform but shows a downward shift of rock mass release spots by 33 m per month over the year, most likely driven by a continuously lowering water table. Freeze-thaw-transitions account for only 5 out of the 49 rockfalls whereas 19 rockfalls were triggered by rainfall events, with a peak lag time of 1 h. Another 17 rockfalls were triggered by diurnal temperature changes and occurred during the coldest hours of the day as well as during the highest temperature change rates. This study is thus the first one to show direct links between proposed rockfall triggers and the spatio-temporal distribution of rockfalls under natural conditions, and extends existing models by providing seismic observations of the rockfall process prior to the first rock mass impacts.
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Cliff
Mass movement
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Collapse is the most devastating disaster in natural landscape scenic spot. There are 34 potential rockfalls distributed in different positions of Helankou. All potential rockfalls pose a serious threat to rock paintings and tourists. Firstly, we comprehensively investigated the genesis, distribution, lithology and geometric characteristics of the 34 potential rockfalls. Secondly, we used the rockfall to analyze the movement process and energy change of the rockfalls. And then we found that there was a high probability that the falling points of the rockfalls can be the rock painting area and the tourist boardwalk. So we decided to use manual cleaning methods to clean up the potential rockfall, because mechanical and blast cleaning could cause irreparable damage to rock paintings. For the large-volume rock, it was better to crush by static crushing agent first. Finally, we did the rock crushing experiment to select the optimal arrangement of static crushing agent. We had the following conclusions. (1)The reasons for the formation of the potential rockfall are the concave of thin-layer, the rock layer level, and the two sets of joints to cut the thick-layer metasandstone. (2)The rockfalls can be divided into three different types: bedrock exposed, solitary belt, and debris flow gully. (3)It is very likely that the falling rocks can fall in the rock paintings area and destroy the rock paintings. (2)The best solution for the control of rockfall is static crushing combined with manual handling. And there is an optimal arrangement of static crushing agent. In short, our study can provide a new way and reference for the prevention of the rockfall disaster in Helankou Rock Painting.
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Abstract The road network in Central Nepal suffered blockades and damage from numerous landslides and rockfalls due to the earthquake sequence in Gorkha, Nepal, in 2015. Additionally, frequent rainstorms in the area contributed to the recurrence of rockfalls and other types of landslides, hindering road infrastructure development and environmental management. Despite the several existing regional and local studies on landslide susceptibility in the area, rockfall-specific analysis is still lacking. In this paper, we assessed rockfall susceptibility in the sections of the Pasang Lhamu highway and the Galchhi-Rasuwagadhi highway in the Rasuwa district using a physically based model. We generated three-dimensional rockfall trajectories along the roads and used them to infer the rockfall susceptibility of the area. We selected potential locations for the initiation of rockfalls based on the optimization of the gridded slope angle, relief, and terrain ruggedness, validated the source map using statistical parameters, and compared them with a field-mapped rockfall source inventory. As a result, we identified which road sections in Ramche, Dandagaun, and Syaprubesi are highly susceptible to rockfalls. We published the field-based inventory of rockfall sources and segment-wise rockfall susceptibility of highways, where a rockfall susceptibility index of 5 indicated very high susceptibility and 1 very low susceptibility. Such findings and maps are helpful for researchers, land planners, developers, government bodies working on disaster risk reduction, and policymakers to design a preliminary framework for rockfall mitigation and sustainable roads.
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Abstract. Rockfall presents an ongoing challenge to the safe operation of transportation infrastructure, creating hazardous conditions which can result in damage to roads and railways, as well as loss of life. Rockfall risk assessment frameworks often involve the determination of rockfall runout in an attempt to understand the likelihood that rockfall debris will reach an element at risk. Rockfall modelling programs which simulate the trajectory of rockfall material are one method commonly used to assess potential runout. This study aims to demonstrate the effectiveness of a rockfall simulation prototype which uses the Unity 3D game engine. The technique is capable of simulating rockfall events comprised of many mobile fragments, a limitation of many industry standard rockfall modelling programs. Five fragmental rockfalls were simulated using the technique, with slope and rockfall geometries constructed from high-resolution terrestrial laser scans. Simulated change detection was produced for each of the events and compared to the actual change detection results for each rockfall as a basis for testing model performance. In each case the simulated change detection results aligned well with the actual observed change in terms of location and magnitude. An example of how the technique could be used to support the design of rockfall catchment ditches is shown. Suggestions are made for future development of the simulation technique with a focus on better informing simulated rockfall fragment size and the timing of fragmentation.
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Abstract. Rockfall presents an ongoing challenge to the safe operation of transportation infrastructure, creating hazardous conditions which can result in damage to roads and railways, as well as loss of life. Rockfall risk assessment frameworks often involve the determination of rockfall runout in an attempt to understand the likelihood that rockfall debris will reach an element at risk. Rockfall modelling programs which simulate the trajectory of rockfall material are one method commonly used to assess potential runout. This study aims to demonstrate the effectiveness of a rockfall simulation prototype which uses the Unity3D game engine. The technique is capable of simulating rockfall events comprised of many mobile fragments, a common limitation of available rockfall modelling programs. Five fragmental rockfalls were simulated using the technique, with slope and rockfall geometries constructed from high-resolution terrestrial laser scans. Simulated change detection was produced for each of the events and compared to the actual change detection results for each rockfall as a basis for testing model performance. In each case the simulated change detection results aligned well with the actual observed change in terms of location and magnitude. An example of how the technique could be used to support the design of rockfall catchment ditches is shown. Suggestions are made for future development of the simulation technique with a focus on better informing simulated rockfall fragment size and the timing of fragmentation.
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During the last decade, large rockfalls occurred on the steep limestone slopes along the Adriatic Coast of Croatia, causing injury to people and serious damage to buildings and traffic facilities. The rockfalls along the limestone slopes were caused by unfavorable characteristics of the rock mass, weathering in combination with heavy rainfall and artificial influences during highway construction. Rockfall protection projects were conducted to protect human lives and facilities from future rockfalls. The rockfall protection program started with rockfall hazard analyses to identify the potential of rockfalls to occur and the potential consequences. At the locations of hazards where related risks were determined, detailed field investigations were conducted. Based on the indentified characteristics of potentially unstable rock masses, analyses of movement and resulting pathways were conducted. The trajectories, impact energy and the height of bouncing are dependent on slope geometry, slope surface roughness and rockfall block characteristics. Two protection measure approaches were adopted: prevention of rockfalls by removing potentially unstable rock mass or installation of rock mass support systems and suspending running rockfall masses with rockfall protection barriers. In this paper, rockfall hazard determination, rockfall analyses and rockfall protection designs for rockfall protection systems at selected locations on the limestone slopes along the Adriatic coast of Croatia are presented.
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