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Reliable computation and local mesh adaptivity in limit analysis
Sysala, Stanislav; Haslinger, Jaroslav; Repin, S.
2019 - English
The contribution is devoted to computations of the limit load for a perfectly plastic model with the von Mises yield criterion. The limit factor of a prescribed load is defined by a specific variational problem, the so-called limit analysis problem. This problem is solved in terms of deformation fields by a penalization, the finite element and the semismooth Newton methods. From the numerical solution, we derive a guaranteed upper bound of the limit factor. To achieve more accurate results, a local mesh adaptivity is used.
Keywords:
limit analysis; von Mises yield criterion; penalization; finite element method; Newton-like method; local mesh adaptivity
Fulltext is available at external website.
Reliable computation and local mesh adaptivity in limit analysis
The contribution is devoted to computations of the limit load for a perfectly plastic model with the von Mises yield criterion. The limit factor of a prescribed load is defined by a specific ...
Možnosti využití 3D laserového skenování v geotechnické praxi
Kukutsch, Radovan; Kajzar, Vlastimil; Šňupárek, Richard; Waclawik, Petr
2019 - Czech
S pronikáním moderních a smart technologií se setkáváme ve všech odvětvích lidské činnosti, oblast hornictví a geotechniky nevyjímaje. Jednou z těchto technologií je i 3D laserové skenování, které za posledních deset let zaznamenalo výrazný technologický pokrok a stalo se nedílnou součástí monitoringu podzemních staveb jako nástroj umožňující komplexní, přesné a nezkreslené zachycení prostorové situace do digitální podoby. Právě tato skutečnost stála za tím, že je od r. 2013 3D laserový skener využíván pracovníky Ústavu geoniky AV ČR, v.v.i. jako nezbytná součást geotechnického a geotechnického monitoringu důlních děl, kdy lze oproti tradičním, zavedeným měřičským metodám, velmi přesně detekovat a kvantifikovat časoprostorové změny vyvolané zásahem člověka do horninového masivu. Nosným projektem posledních let byl monitoring napěťodeformačního stavu horninového masivu při dobývání 30. sloje v rámci zkušebního provozu dobývací metody Room and Pillar (chodba-pilíř) v ochranném pilíři jam Dolu ČSM, kde vedle mnoha jiných měřicích instrumentů bylo 3D laserové skenování využíváno pro konvergenční měření chodeb, zejména ale pro zachycení veškerých deformačních změn na ponechaných pilířích. Doplňkovou funkcí bylo komparativní hodnocení s výsledky jiných nástrojů, kupř. s údaji naměřenými pomocí horizontálních extenzometrů. Předmětem příspěvku tak bude všeobecné vytyčení možností uplatnění 3D laserového skenování v geotechnické praxi, a to na prostorových datech pořízených během monitoringu trvajícím bezmála 3,5 roku, kdy byly na Dole ČSM zachyceny významné fenomény v pohybu stěn pilíře a vyzvedávání počvy v řádu desítek cm, místy až 100 cm. We are experiencing the penetration of modern and smart technologies in all sectors of human activity, including mining and geotechnics. One of these technologies is 3D laser scanning, which has seen significant technological advancements over the last decade and has become an integral part of underground construction monitoring as a tool to enable comprehensive, accurate and unbiased capture of the spatial situation in digital form. This development was behind the fact that since 2013, 3D laser scanner has been used by the Institute of Geonics of the Czech Academy of Sciences as a necessary part of the geotechnical monitoring of mine works, when it is possible to precisely detect and quantify the time-space changes caused by man's intervention in the rock mass compared to the traditional established measuring methods. A leading project of recent years was the monitoring of the strain stress state of the rock massif during the 30th seam extraction during the trial operation of the Room and Pillar extraction method in the CSM Mine shaft safety pillar where, besides many other measuring instruments, 3D laser scanning was used for the convergence measuring of roadways, especially for capturing any deformation changes on the permanent pillars. A complementary function was the comparative evaluation with the results of other tools, e.g. with data measured by horizontal extensometers. The subject of the article will be a general description of the possibilities of using 3D laser scanning in geotechnical practice on spatial data acquired during the monitoring lasting almost 3.5 years, when important phenomena were detected in the movement of the pillar walls and the floor heave in the CSM Mine in the tens of cm, sometimes up to 100 cm.
Keywords:
3D laser scanning; room and pillar; roadways deformation
Available at various institutes of the ASCR
Možnosti využití 3D laserového skenování v geotechnické praxi
S pronikáním moderních a smart technologií se setkáváme ve všech odvětvích lidské činnosti, oblast hornictví a geotechniky nevyjímaje. Jednou z těchto technologií je i 3D laserové skenování, které za ...
Application of bentonite-manganese oxide composites in removal of heavy metals
Dolinská, S.; Znamenáčková, I.; Tomčová, J.; Valovičová, Věra; Vaculíková, Lenka; Plevová, Eva
2019 - English
The paper is aimed on the using of non-homogeneous bentonites coated by manganese oxides for the removal of heavy metal cations from the water solutions. In the first stage Slovak natural bentonite was converted to sodium form using by Na2CO3 as the activating agent. After that the manganese oxides were precipitated on the surface of natural and sodium activated bentonite, respectively. The structural changes before and after the modifications of bentonites were characterized by X-ray diffraction analyses and X-ray photoelectron spectroscopy. To compare the sorption properties of the natural bentonite and modified bentonites, sorption experiments of Cd2+ from aqueous solutions were done.
Keywords:
bentonite; composites; adsorption
Available in digital repository of the ASCR
Application of bentonite-manganese oxide composites in removal of heavy metals
The paper is aimed on the using of non-homogeneous bentonites coated by manganese oxides for the removal of heavy metal cations from the water solutions. In the first stage Slovak natural bentonite ...
Thermal behaviour of organically modified smectites
Plevová, Eva; Vaculíková, Lenka; Valovičová, Věra; Simha Martynková, G.
2019 - English
The smectites were modified with different types of alkylammonium cations. The X-ray powder diffraction was used to calculate the values of the basal space of the modified smectites to confirm the intercalation of cations into the structure. The montmorillonites were also characterized by means of FTIR spectroscopy, which proved sorption or intercalation of the alkylammonium cations too. Thermal behaviour of the smectites was investigated by simultaneous thermogravimetry and differential thermal analysis. The temperatures of dehydratation and dehydroxylation and the temperatures related to total melting and recrystallization generally changed. Study of temperatures changes together with determination of kinetic parameters helped to obtained a comprehensive assessment of smectite thermal stability.
Keywords:
smectites; intercalation; thermal analysis
Available in digital repository of the ASCR
Thermal behaviour of organically modified smectites
The smectites were modified with different types of alkylammonium cations. The X-ray powder diffraction was used to calculate the values of the basal space of the modified smectites to confirm the ...
Effects of abrasives during accelerated simulation of mechanical corrosion of cement composites using abrasive water flow
Hlaváček, Petr; Sitek, Libor; Klichová, Dagmar; Bodnárová, L.
2019 - English
The paper deals with the use of the abrasive water flow technology in an accelerated simulation of the process of mechanical degradation of surface layers of cement-based composites by flowing liquids. Effects of the abrasive particle size and the mass flow rate of abrasives in an abrasive water flow impacting on the surface of concrete samples have been studied. In addition, suitability of the application of the abrasive water flow for the simulation of real situation of the surface wear by flowing liquids has been evaluated.
Keywords:
cement-based composite; erosion; abrasion; cavitation; high-speed water flow; abrasive material
Available at various institutes of the ASCR
Effects of abrasives during accelerated simulation of mechanical corrosion of cement composites using abrasive water flow
The paper deals with the use of the abrasive water flow technology in an accelerated simulation of the process of mechanical degradation of surface layers of cement-based composites by flowing ...
Evaluation of fracture response of Silesian granite specimens via Effective Crack Model approach and finite element analysis
Malíková, L.; Vavro, Leona; Vavro, Martin; Keršner, Z.
2019 - English
The paper is focused on the advanced evaluation of fracture tests of selected rock specimens. Assessment of fracture response of chevron notch cylindrical specimens of Silesian granite subjected to three-point bending test was performed. The effective crack model is used and academic software chevroncylinder (author Petr Frantík) based on the finite element method is applied for the analyses. Based on the described procedures, estimation of maximum values of the effective fracture toughness are established and discussed.
Keywords:
granite; fracture test; chevron notch; load–displacement diagram; effective crack model
Available in digital repository of the ASCR
Evaluation of fracture response of Silesian granite specimens via Effective Crack Model approach and finite element analysis
The paper is focused on the advanced evaluation of fracture tests of selected rock specimens. Assessment of fracture response of chevron notch cylindrical specimens of Silesian granite subjected to ...
Cultural heritage and geodiversity of landforms in the landscape of the Archdiocese of Olomouc
Kirchner, Karel; Kuda, František; Kubalíková, Lucie; Havlíček, M.; Machar, I.; Pechanec, V.
2018 - English
Within the framework of the NAKI II project – Cultural heritage of landscape of the Archdiocese of Olomouc - research, presentation and management (DGB 16P02B014), we focus on the results that will contribute to the sustainable development of regional cultural identity through applied cultural heritage research in the cultural landscape of the area of interest. As part of the material cultural heritage, we include the landforms that originated from the conscious activity of man - the anthropogenic relief forms. These landforms complement the geodiversity of the landscape and are referred to as secondary geodiversity. Therefore, their identification and interpretation will make it possible to complement and enhance the diversity of cultural heritage and to specify the development of the cultural landscape. The first results from the area of Central Moravia will be presented with the using of the historical maps, the digital model of the relief DMR5G and the field research.
Keywords:
cultural heritage; secondary geodiversity; Archdiocese of Olomouc
Available at various institutes of the ASCR
Cultural heritage and geodiversity of landforms in the landscape of the Archdiocese of Olomouc
Within the framework of the NAKI II project – Cultural heritage of landscape of the Archdiocese of Olomouc - research, presentation and management (DGB 16P02B014), we focus on the results that will ...
Tourist interest in illicit zone of ice caves
Nováková, Eva; Kuda, František; Kubalíková, Lucie
2018 - English
Ledové sluje (Ice Caves) in the Podyjí National Park represents one of the most spectacular sites within the area. It consists of the large boulder field and several pseudokarst caverns on the north-western slope of the ridge that are very important from the ecological and geomorphological point of view. The access to the site is restricted for the visitors of National Park as there exists a risk of damage and disturbance of these unique phenomena, tourist can use the marked paths leading around the site, they can reach the top part of the ridge. Currently, there are only several persons who have legal access to the site (employees of the National Park Administration and other researches with the permission issued by NP Administration). However, the installed sensor that counts the passages proved that the site is visited more frequently than it should be. The number of people who visit this site (situated within the first zone of National Park where there is no marked path and so the access is forbidden by decree) is quite alarming. Based on these findings, some proposals for the solution of this unfavourable situation are proposed and other possibilities how to avoid this undesirable phenomenon are discussed.\n
Keywords:
Podyji National Park; restricted area; passages monitoring
Available in a digital repository NRGL
Tourist interest in illicit zone of ice caves
Ledové sluje (Ice Caves) in the Podyjí National Park represents one of the most spectacular sites within the area. It consists of the large boulder field and several pseudokarst caverns on the ...
Stabilita chodeb při dobývání uhlí metodou komora-pilíř ve velkých hloubkách
Šňupárek, Richard; Waclawik, Petr; Kukutsch, Radovan
2018 - Czech
Za účelem ověření napěťo-deformačních projevů dobývání metodou chodba-pilíř v hloubce až 900 m pod povrchem byl implementován rozsáhlý systém geotechnického monitoringu a sledování deformací a pohybu povrchu. Na základě výsledků napěťo-deformačního monitoringu byla provedena podrobná analýza stability chodeb z hlediska konvergence, deformačního chování okolního horninového masivu a funkce použité výztuže ve dvou sledovaných oblastech s rozdílnými geologickými i provozními podmínkami. In order to verify the stress-strain state of mining using the room and pillar method at a depth of up to 900 m below the surface, an extensive system of geotechnical monitoring and observation of deformations and surface movement was implemented. Based on the results of the stress-strain monitoring, detailed analysis of roadway stability from the point of view of the convergence, deformation behavior of the surrounding rock mass and the function of the reinforcement used in the two monitored areas with different geological and operational conditions was carried out.
Keywords:
room and pillar; monitoring; roadways stability
Available in a digital repository NRGL
Stabilita chodeb při dobývání uhlí metodou komora-pilíř ve velkých hloubkách
Za účelem ověření napěťo-deformačních projevů dobývání metodou chodba-pilíř v hloubce až 900 m pod povrchem byl implementován rozsáhlý systém geotechnického monitoringu a sledování deformací a pohybu ...
Geotourism within urban areas: New ways of promotion of natural and cultural heritage (Case study from Brno City).
Kubalíková, Lucie; Bajer, A.
2018 - English
Geotourism is based especially on geodiversity, but it also uses the cultural-historical aspects of an area, it is linked to the education and counts with active engagement of local people. Currently, geotourism is developed mainly within rural areas, but there are activities that point on the geodiversity and its importance within urban areas. Rational and sustainable use of geodiversity within urban areas can represent an alternative to the traditional tourist destinations and contributes to the understanding of the importance and necessity of protection of geodiversity itself. Geodiversity, respectively geoheritage within urban areas does not include only issues of primary (natural) geodiversity (substrate, Iandforms, soils), but also anthropogenic landforms and processes (secondary geodiversity), hydrological features (wells, millraces) and geodiversity ex-situ (museum collections, building material). The paper presents this new form of tourism and gives examples of selected geodiversity/geoheritage features within the Brno city.
Keywords:
geodiversity; geoheritage; urban geotourism; Brno
Fulltext is available at external website.
Geotourism within urban areas: New ways of promotion of natural and cultural heritage (Case study from Brno City).
Geotourism is based especially on geodiversity, but it also uses the cultural-historical aspects of an area, it is linked to the education and counts with active engagement of local people. Currently, ...
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