|
|
Comprehensive study of the sandstone rock forms deterioration (Case study: Pravčická brána Arch, Bohemian Switzerland National Park)
Vařilová, Zuzana ; Přikryl, Richard (advisor) ; Vilímek, Vít (referee) ; Mikuláš, Radek (referee)
This PhD thesis contains the results of comprehensive research into the Pravčická brána Arch and surrounding sandstone massifs with focus on gaining more knowledge about natural dynamics and evolution of this rock formation, its current level of stability and the weathering processes it displays. Non-destructive methods were used for this comprehensive study; these ranged from detailed field documentation to monitoring temperature regime of the rock and included application of a geophysical survey and control monitoring of the course of arch body deformation. Laboratory testing was carried out for strength parameters and salt efflorescences together with weathered sandstones were analysed for chemical compounds. Main operating factors were monitored simultaneously, which particularly involved changes in external temperature, degree of sunlight and chemical composition of rainfall. Conventional as well as entirely new assessment procedures were used in synthesis and interpretation of the data collected, including knowledge of nonlinear dynamics of complex systems. The survey was designed to fully respect the protective conditions of the site, to make follow-up activities possible in future and to monitor any possible negative changes in the rock massif. The main results incorporate description of...
|
|
|
Origin and evolution of silcretes
Kohoutová, Iveta ; Zachariáš, Jiří (advisor) ; Adamovič, Jiří (referee)
Summary: Silcretes are rocks with high content of SiO2 (usually more than 90 wt. %) formed by mobilization of SiO2 during weathering processes. Silcretes formed near the Earth's surface by soil weathering in warm and humid climate are termed as pedogenic silcretes. Another type of silcrete is groundwater silcrete, whose origin is usually associated with the groundwater table and depths of 5-50 m below the surface and arid to semi-arid climate. The third type of silcretes is associated with evaporites. Its genesis is complicated; as well it is difficult to date this silicification. There are four types of silcrete textures: GS-, F-, M-, C- textures; the most common is the F-texture. In the Czech Republic silcretes are more known under the term "sluňáky" or "quartzite". Indeed, in every country where they occur, have their own specific name. Silcretes are essentially composed of SiO2, minor constituents represent heavy minerals and/or feldspar. Cement is mostly α-quartz, chalcedony and opal. Average thickness of silcretes is 1-3 m, rarely 5 meters. Main source of SiO2 is chemical weathering of silicate minerals or quartz dust grains carried by wind and deposited on natural barriers, like blades of grass. There are two models of silcrete formation: lateral and vertical transport model SiO2. Sedimentary...
|
|
|
Microforms of sandstone relief and their using in relative dating
Krbcová, Klára ; Křížek, Marek (advisor) ; Engel, Zbyněk (referee)
Microforms and mesoforms play the main role in the sandstone relief. Their origin is conditioned by some processes, the main are weathering and erosion. Based on the background research, the deffinition, classification, diagenesis and occurrence of sandstones was described. The second part of the bachelor thesis is focused on the mechanism of weathering and erosion. The microforms and mesoforms of the sandstone relief were divided into groups according to the guiding process of their origin. The description of the sandstone forms, the way of their origin, the stage of development and their extension were described. In the practical part of the bachelor thesis, the microforms in the gorge Apatyka in CHKO Kokořínsko were analyzed. The practical part was focused expecially on honeycombs, because their extension in the gorge is huge and they enable the complex analyse of their location in the gorge and in the rock outcrops. Using suitable methods it was found, that the honeycombs are located primarily in the eastern quadrant, their coverage decrease with the decreasing height of the rock outcrops and their presence in the lowest and the highest parts of the rock walls is limited. The second part of the fieldwork was focused on the relative dating of the parts of the gorge with honeycombs. The odlest part of the...
|
|
|
The effect of artificial weathering on overburden properties
Zadinová, Radka ; Bartuška, Martin (referee) ; Frouz, Jan (advisor)
Surface mining of coal cause massive changes of landscape. Dumps, heaps and tailings created vast areas in post mining landscape. Soil formation is influenced by the weathering process. Sample-the most common substrates have been subject of accelerated weathering. Samples were watered by distilled water, left to soak in, then froze, thaw and dried. This cycle was repeated twenty times. Before the experiment and after experiment pH, conductivity, organic matter loss on ignition, grain size and water absorption were measured. Before and after the experiment were tested for toxicity to plants using yellow mustard seeds (Sinapis alba). Accelerated weathering showed the possible development of weathering spoil substrates over time namely shift of pH towards neutral value, and increase in water holding capacity, despite of this no changes in plant toxicity in toxic substrates were found.
|
|
|
Modulus of elasticity of natural stone
Hoduláková, Michaela ; Cikrle, Petr (referee) ; Kocáb, Dalibor (advisor)
The value of the modulus of elasticity of concrete depends on the concrete composition (particularly on the aggregate used). The contemporary construction industry literature lacks comprehensive studies of the modulus of elasticity for each type of the rock stone. Therefore, this study focuses on testing and comparing the modulus of elasticity of selected types of rock stones used for the production of crushed coarse aggregates into the concrete. The modulus of elasticity are determined by static and dynamic methods. The work also deals with the modulus of elasticity of granite in different stages of weathering.
|
|
|
Povrchová úprava dřevěných fasád
Slováčková, Hana
This thesis deals with monitoring changes in surface finishing of spruce and larch wood in outdoors. Using outdoor weathering tests the properties of two kinds of paints were tested by - a thin glaze and oil paint, two shades from each. In this work, the influence of the composition of the paint on its durability and light fastness was examined. This issue is closely related to the resistance of coatings to weathering, including solar radiation (UVA and UVB), atmospheric oxygen, relative humidity, temperature, precipitation, biological attack, chemical impacts (air pollution, acid rain, etc.).
|
|
|
Potholes of Česká Kanada
KUBOVÁ, Alena
This Bachelor thesis looks into potholes of nature park Česká Kanada. The theoretical part of the thesis summarises the character of the nature park, formation of potholes and other types of landforms occurring in the region. The practical part deals with selected pothole localities, where the spatial relationship of pothole beds and primary joints is being researched. The results show that pothole beds are concordant with joint planes. Some locations revealed two generations of potholes.
|
|
|
Zmapování a zhodnocení geodynamických jevů na území Národního parku České Švýcarsko
IG Ateliér s.r.o., Hřensko
Práce provedené v rámci tohoto projektu byly spojené s terénním vyhledáváním nestabilních skalních objektů, či jiných projevů nestabilit území, jako je např. eroze. Zjištěné nestabilní skalní útvary byly dokumentovány, jejich pozice byly vyznačeny v příslušné mapě a na vybraných skalních objektech bylo zahájeno bezpečnostní kontrolní sledování. Všechny výstupy spojené s řešením projektu byly v závěrečné fázi převedeny do digitální podoby dle požadavků Správy národního parku.
|
|
|
Zmapování a zhodnocení geodynamických jevů na území Národního parku České Švýcarsko
IG Ateliér s.r.o., Hřensko
Obsahem táto zprávy je přehled a zhodnocení prací vykonaných v průběhu roku 2003. V souhrnu byly provedeny: stabilní průzkum skalních svahů v oblasti Dolského mlýna, v oblasti Jetřichovice - Mariina skála (též Tetřevna), v Kyjovském údolí, v oblasti Loupežnický hrádek - Malá Pravčická brána - Větrovec, v oblasti Pravčická brána - Tři prameny, v Tiché soutěsce a Divoké soutěsce. Dále bylo provedeno odebrání vzorků pískovce z různých rajonů pro testování jejich základních fyzikálně-mechanických parametrů.
|
|
|
Zmapování a zhodnocení geodynamických jevů na území Národního parku České Švýcarsko
IG Ateliér s.r.o., Hřensko
Obsahem táto zprávy je přehled a zhodnocení prací vykonaných v průběhu roku 2002. V souhrnu byli provedeny: stabilní průzkum skalních svahů nad státními silnicemi z Janova do Doubice, obce Vysoká Lípa a Jetřichovice, Gabrielina stezka z Mezní Louky na Pravčickou bránu. Dále bylo provedeno odebrání vzorků pískovce z oblasti skalního řícení v lednu 2002 ve Ferdinandově soutěsce a testování jejich mechanických parametrů (pevnost v tlaku). Probíhal též odběr vzorků podzemních vod v různých částech parku, u nichž byla provedena chemická analýza složení z hlediska vlivu srážkových a podzemních vod na rychlost zvětrávání.
|
guest ::
