scholarly journals Assessing the effect of lithological setting, block characteristics and slope topography on the runout length of rockfalls in the Alps and on the island of La Réunion

2021 ◽  
Vol 21 (3) ◽  
pp. 1159-1177
Author(s):  
Kerstin Wegner ◽  
Florian Haas ◽  
Tobias Heckmann ◽  
Anne Mangeney ◽  
Virginie Durand ◽  
...  
Keyword(s):  
Size Distribution ◽  
Block Size ◽  
Terrain Parameters ◽  
The Alps ◽  
Good Proxy ◽  
Study Sites ◽  
The One ◽  
Block Sizes ◽  
Block Size Distribution

Abstract. In four study areas within different lithological settings and rockfall activity, lidar data were applied for a morphometric analysis of block sizes, block shapes and talus cone characteristics. This information was used to investigate the dependencies between block size, block shape and lithology on the one hand and runout distances on the other hand. In our study, we were able to show that lithology seems to have an influence on block size and shape and that gravitational sorting did not occur on all of the studied debris cones but that other parameters apparently control the runout length of boulders. Such a parameter seems to be the block shape, as it plays the role of a moderating parameter in two of the four study sites, while we could not confirm this for our other study sites. We also investigated the influence of terrain parameters such as slope inclination, profile curvature and roughness. The derived roughness values show a clear difference between the four study sites and seem to be a good proxy for block size distribution on the talus cones and thus could be used in further studies to analyse a larger sample of block size distribution on talus cones with different lithologies.

scholarly journals Assessing the effect of lithological setting, block characteristic and slope topography on the runout length of rockfalls in the Alps and on the La Réunion island

2020 ◽  
Author(s):  
Kerstin Wegner ◽  
Florian Haas ◽  
Tobias Heckmann ◽  
Anne Mangeney ◽  
Virginie Durand ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Block Size ◽  
Axial Ratio ◽  
High Mountain ◽  
Slope Inclination ◽  
Terrain Parameters ◽  
Longitudinal Profiles ◽  
Study Sites ◽  
La Réunion Island ◽  
Block Sizes

Abstract. In high mountain regions, rockfalls are common processes, which transport different volumes of material and therefore endanger populated areas and infrastructure facilities. In four study areas within different lithological settings, LiDAR (light detection and ranging) data were acquired for a morphometric analysis of block sizes, block shapes and talus cone characteristics. Based on these high-resolution terrestrial laser scanning (TLS) data, the three axes of every block larger than 0.5 m in the referenced point cloud were measured. Block sizes and shapes are used to investigate them in the context of runout distances and to analyse the spatial distribution of blocks on the talus cone. We also investigate the influence of terrain parameters such as slope inclination, roughness and profile curvature (longitudinal profiles). Our study shows that the relation of block size within different lithological settings on runout length is complex, because we can neither confirm nor reject the theory of gravitational sorting. We also found that the block shape (axial ratio) does not have a simple influence on runout length, as it plays the role of a moderating parameter in two study sites (Gampenalm: GA, Dreitorspitze: DTS) while we could not confirm this for Piton de la Fournaise (PF) and Zwieselbach valley (ZBT). The derived roughness values show a clear difference between the four study sites. This also applies for the parameter of slope inclination and longitudinal profiles.

scholarly journals CSD correction as a tool for estimating 3d block size distribution.

2013 ◽  
Vol 47 (4) ◽  
pp. 1854
Author(s):  
M. Rusi ◽  
P. Hoxha
Keyword(s):  
Rock Mass ◽  
Size Distribution ◽  
Three Dimensional ◽  
Block Size ◽  
Economic Consequences ◽  
Major Question ◽  
Thin Sections ◽  
Matrix Rock ◽  
Tbm Excavation ◽  
Block Size Distribution

For the headrace Moglicë-Grabovë, part of Devoll Hydropower Project in Albania, two different techniques of tunnelling are planned: DS TBM for the Flysch series starting in Moglicë and Drill & Blast for the Ophiolite section, starting in Grabovë. A major question concerning the tunnelling seems to find the point where DS-TBM excavation from the Moglicë side should stop to “wait” for the Drill&Blast excavation from the Shemsit access tunnel side. Assumed that the so called “block in matrix” rock mass is very unfavourable, respectively disqualifying for TBM excavation. These mixtures of hard blocks embedded in weaker and finer matrix that are very difficult to characterize, frequently challenge the engineering geologists with the characterization, design and construction problems associated with them. Evaluating Block Size Distribution in the BiM rock zone of this project area has been only the first step in characterizing all the geological and geotechnical parameters of the rock mass which will influence a decision that has major economic consequences. CSDCorrections 1.39 is the program used to convert the two dimensional data gathered from thin sections, outcrops, photographs etc. to true three dimensional crystal size distributions (CSD).

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