The relevance of rock shape over mass—implications for rockfall hazard assessments

The mitigation of rapid mass movements involves a subtle interplay between field surveys, numerical modelling, and experience. Hazard engineers rely on a combination of best practices and, if available, historical facts as a vital prerequisite in establishing reproducible and accurate hazard zoning. Full-scale field tests have been performed to reinforce the physical understanding of debris flows and snow avalanches. Rockfall dynamics are - especially the quantification of energy dissipation during the complex rock-ground interaction - largely unknown. The awareness of rock shape dependence is growing, but presently, there exists little experimental basis on how rockfall hazard scales with rock mass, size, and shape. Here, we present a unique data set of induced single-block rockfall events comprising data from equant and wheel-shaped blocks with masses up to 2670 kg, quantifying the influence of rock shape and mass on lateral spreading and longitudinal runout and hence challenging common practices in rockfall hazard assessment.

Effects of Na2SO4 Concentration and Surface Shape on The Weathering of Granite During Wet-Dry Cycling

The presence of salts during cyclic wet and dry conditions can cause weathering of rock and is the main cause of damage to ancient and modern buildings. Accordingly, salt weathering, especially of granite, has aroused great interest. Determining the relationship between wet-dry cycling and the physical properties of rock is of great significance to geotechnical engineering. In this paper, granite samples were processed into two shapes (round and semicircular) and subject to 0, 10, 20, 30, 40 and 50 wet-dry cycles, with the wetting achieved with 0%, 5%, 10% or 20% Na2SO4 solution. The mass loss, roughness and indentation hardness of granite samples all changed to some extent with cycle number, with greater changes occurring at higher salt concentrations. Rock shape also affects the extent of weathering damage, as surface area and features such as corners facilitate the ingress of salt solution.

Investigation of the Permeability of Soil-rock Mixtures Using Lattice Boltzmann Simulations

Based on the discrete element method and the proposed virtual slicing technique for three-dimensional discrete element model, random pore-structural models of soil-rock mixtures are constructed and voxelized. Then, the three-dimensional lattice Boltzmann method is introduced to simulate the seepage flow in soil-rock mixtures on the pore scale. Finally, the influences of rock content, rock size, rock shape and rock orientation on the simulated permeability of soil-rock mixtures are comprehensively investigated. The results show that the permeability of soil-rock mixtures remarkably decreases with the increase of rock content. When the other conditions remain unchanged, the permeability of soil-rock mixtures increases with the increase of rock size. The permeability of soil-rock mixtures with bar-shaped rocks is smaller than that of soil-rock mixtures with block-shaped rocks, but larger than that of soil-rock mixtures with slab-shaped rocks. The rock orientation has a certain influence on the permeability of SRMs, and the amount of variation changes with the rock shape: when the rocks are bar-shaped, the permeability is slightly decreased as the major axes of these rocks change from parallel to perpendicular with respect to the direction of main flow; when the rocks are slab-shaped, the permeability decreases more significantly as the slab planes of these rocks change from parallel to perpendicular with respect to the direction of main flow.

THE DISCOVERY OF ICE AGE CAVE ART AT LA MARCHE (VIENNE, FRANCE)

Статья представляет краткое описание открытия первого изображения на стенах палеолитической пещеры Ла-Марш (Люссак-ле-Шато, Вьенна, Франция). Этот памятник всемирно известен благодаря тому, что в нем было найдено огромное количество гравированных каменных плиток с гравировками, датируемыми более чем 14 000 л. н. Гравировки расшифровывались в течение 25 лет и были полностью опубликованы доктором Л. Палем. Всегда считалось, что на стенах этой пещеры изображений нет. Первая информация о том, что на стенах в Ла Марш есть какие-то следы, была получена автором еще в 2004 г., и вот недавно им была обнаружена первая фигура: голова бизона, сочетающая технику гравировки и использование естественной скальной формы. По стилю она напоминает знаменитый скульптурный фриз в гроте Англь-сюр-Л Англен, расположенный в том же регионе, что и Ла Марш, и датируемый тем же временем. A brief account of the discovery of the first parietal figure in the Ice Age rock-shelter of La Marche (Lussacles-Chteaux, Vienne, France). The site was already world-famous for its huge collection of engraved plaquettes of stone, dating to more than 14,000 years ago, which were deciphered and published over the course of 25 years by Dr Lon Pales. But it was always thought that the rock-shelter in which the plaquettes were found had undecorated walls. In 2004 I was given information which suggested that there might be markings, and I eventually discovered a first parietal figure, a head of a bison, comprising engraving and use of natural rock shape. The style was similar to that of the great sculpted frieze at Angles-sur-lAnglin, in the same region, which is of the same date as La Marche.

MORPHOLOGIC CLASSIFICATION OF THE BESKIDS ROCKS IN THE UKRAINIAN CARPATHIANS

The article deals with morphological classification of the sandstone rocks in the Ukrainian Carpathians Beskids. By the methods of field measurements and mathematical computations the rock peaks heights, their shape, basement lengths and strata thickness have been calculated. The highest rock peaks in the Beskids amounts 32–37 m. The classification from the morphological point of view on the base of rock forms studying has been done. All rocks are divided in two classes: the rocks-outliers and the rocks-outcrops. Among the rocks-outliers 4 types are defined: spire-shaped, chain-shaped, arc-shaped and combined. Spire-shaped rocks are divided into subtypes: tower, spoke and needle. Among the chain-shaped rocks 3 subtypes are defined: wall, bloc and slab. The rocks of combined form are divided into subtypes: 1) with defined form – those of the rocks which are similar to certain objects and 2) undefined forms (cliffs). Among the rocks-outcrops three types are defined: cliff-shaped, canyon-shaped and angular ones. The class of rocks-outliers occurs most often. Among the types the rocks-towers occur most often. They dominate in the rock formations of Urych, Yamelnytsia and Bubnyshche. Many bloc-shaped and plate-shaped rocks are located on the Kliuch Ridge, in Bubnys’ki Rocks, Yamelnytsia. There are rocks-walls of 50–60 m in Urych and Yamelnytsia. The longest rock-wall in Danylov tract near Yamelnytsia has been investigated. Its length is 150 m and height is 17 m. Some needle and spoke rocks are situated in Bubnys’ki Rocks (Odinets’ Rock, Golets’ Rock) and Urych (Hostryi Kamin’ (Sharp Stone) Rock. Unique types are very rare. For instance: Bronenosets’ Rock in Bubnys’ki Rocks (this rock has shape of sail), Sokil (Falcon) Rock in the Kliuch Ridge, mushroom-shaped rock in Yamelnytsia. There is also unique arc-rock in the Kliuch Ridge. In the class of rocks-outcrops the types of cliff and canyon occur equally. The angular-shaped rocks are rarer. The cliff-shaped rocks are situated near Sokolova Mountain, Pozhernytsia Mountain and Kniazhi (Princes) Rocks near Tyshivnytsia. Unique rocks-canyons, the effects of tectonic breaking and gravity-erosion processes, occur on the Kliuch Ridge. The worked out morphological classification of rocks can be used by ascertaining features of rock morphogenesis with education and scientific purposes as well as by assessment of safety level and protection possibilities. Morphological types of the rocks can be considered as valuable objects of geomorphologic heritage and attractions for geo-tourism. Key words: rocks; morphology type of the rock; rock shape; Beskids of Ukrainian Carpathians.