Ustav struktury a mechaniky hornin AV CR

Prague, Czech Republic

Ustav struktury a mechaniky hornin AV CR

Prague, Czech Republic
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Novak F.,Technopark Kralupy VSCHT Prague | Machovic V.,Ustav struktury a mechaniky hornin AV CR | Machovic V.,Laborator molekulove spektroskopie VSCHT Prague | Hrabalova H.,Technopark Kralupy VSCHT Prague | Novotna M.,Laborator molekulove spektroskopie VSCHT Prague
Chemicke Listy | Year: 2017

The modern FTIR spectrometry enables both qualitative and quantitative analysis of humic (HS) and humiclike substances. Priority of this method in comparison with13C NMR or titration analysis of functional groups consists in small quantity of consumed sample and time. The availability of FTIR spectrometers for smaller laboratories represents an additional advantage. However, the FTIR spectrometry demands high purity of humic substances, in particular low contents of illite minerals, water, and residues of reagents used for extraction or coagulation (diphosphate, sulphate or hydrofluoric acid). Namely, in analysis of large sample series, the FTIR spectrometry can successfully compete with the (in other respects irreplaceable)13C NMR spectrometry. Besides the transmission (KBr) technique of FTIR spectra measurement, at which undesirable ion exchange occurs, the DRIFT and namely ATR (Attenuated Total Reflection) techniques are now widely applied for quantitative analysis of HS. The FTIR spectra-based classification of humic substances, which is rarely applied till now, seems to be a prospective tool. The FTIR spectrometry can widely be used also to study the humus biotransformation, interactions with metal ions, etc. © 2017, Czech Society of Chemical Engineering. All rights reserved.

Slavik M.,Charles University | Bruthans J.,Charles University | Schweigstillova J.,Ustav Struktury A Mechaniky Hornin AV CR | Falteisek L.,Charles University
Geoscience Research Reports | Year: 2017

Over recent years, the effect of biocolonization of sandstone surfaces has been widely discussed. A large number of studies proved deteriorating effect of organisms. On the other hand, some studies demonstrated that biologically-initiated rock crust protects sandstone surfaces against various weathering processes, and therefore decreases the erosion rate of sandstones. In previous studies, biologically-initiated rock crust, developed on weak sandstone surfaces in the Strelec Quarry (Bohemian Paradise, Czech Republic), was observed, and two potential ways of surface protection against weathering were indicated: Tectonic hardening, and biocolonization. Recently, it was proven that the biologically-initiated rock crust in the quarry protects underlying material against rain and flowing water erosion, and significantly changes the sandstone hydraulic properties. The presented study relates to the previous investigations. Biologically-initiated rock crust in the quarry was studied from mineralogical and biological points of view. Mechanical properties and resistance to erosion of biologically-initiated rock crust at tectonic surfaces were compared with the non-Tectonic surfaces. Results of the studied crust tensile strength were compared to eight sandstone outcrops in the Bohemian Paradise and the Ceska Lfpa region outside the quarry. Based on sequencing and microscopy of the biologically-initiated rock crust in the quarry, the organic matter is mostly formed by various fungi and green algae. The surface zone is enriched with kaolinite and clay-To-silt sized quartz particles (Table 1). Using the drilling resistance method, relative erodibility indicator (REI) and measuring of tensile strength in situ, it was determined that there is no relevant difference in the protection by biologically-initiated rock crust between tectonic and non-Tectonic surfaces (Table 1, Fig. 4). Only measuring of tensile strength in laboratory showed ∼6 times higher increase in case of biocolonized tectonic surfaces. We believe this is caused by heterogeneity of sampled material or by damage of the material during its trans-port. Since all the other methods found no difference, biocolonized tectonic surfaces in the quarry seem to have generally the same mechanical properties as non-Tectonic biocolonized surfaces. From comparison of tensile strength of biologically-initiated rock crust in the quarry with eight crusts in natural outcrops outside the quarry, it was demonstrated that the studied surfaces in the quarry are surprisingly resistant. Their mechanical properties are comparable to natural biologically-initiated rock crusts in sandstone rock cities (Fig. 6). Since the biologically-initiated crust in the quarry developed within the last 10-50 years, it seems that organisms are capable to harden and stabilize fresh surfaces in several years or in a few decades. Such a rate is much higher than the mineral case hardening. The stabilizing effect of organisms may provide a primary protection against weathering after rock falls, at quarry faces, road cuts, and other rapidly eroded sandstone surfaces. However, protective effect of biologically-initiated rock crust may vary according to type of material, age and degree of erosion. The stabilizing effect should be quantified as a ratio of resistance (strength) of surface and its subsurface.

Salek O.,Charles University | Matolin M.,Charles University | Taborik P.,Charles University | Stepancikova P.,Ustav Struktury A Mechaniky Hornin AV CR
Geoscience Research Reports | Year: 2014

Concentrations of natural radionuclides of K, U and Th along vertical profile of a research trench studying the Sudetic Marginal Fault were established by detailed focused gamma-ray spectrometric measurements. Geological scheme of the profile is shown in the Fig 1. Analyses of K, U, Th were carried out by two gamma-ray spectrometers, i.e. GS-256 and newly introduced GT-40S (Georadis). The GS-256 is a portable gamma-ray spectrometer of standard design, which was calibrated at calibration facility Stráž pod Ralskem, Czech Republic. Focusing of GS-256 detector was achieved by placing the probe in a ring-shaped lead shield (thickness 30 mm, height 130 mm, inner diameter 140 mm, weight 21 kg). Since the lead shielding is changing instrument's response to gamma-rays and its calibration constants, it is necessary to apply shielding correction factors when determining K, U and Th (Table 1). The gamma-ray spectrometer GT-40S is specially designed for focused measurements. The lead shielding (thickness 25 mm, inner diameter 70 mm, weight 9 kg) is built into the probe. The GT-40S was calibrated using Grasty's transportable calibration pads. The results of measurements by GS-256 gamma-ray spectrometer on profiles 1 and 2 are shown in Fig 2. The comparison of results acquired by using the GS-256 and GT-40S instruments is presented in Fig 3. The abnormality of the obtained radiometric data was statistically treated and tested using the range of ±3S (standard deviation) of the mean. The test has shown thorium anomaly to be bound to rocks of the fault zone, while concentrations of potassium and uranium have not indicated any significant change or affinity (Table 2, Fig. 2). Statistical identity of the results obtained by using the GS-256 and GT-40S instruments was tested by Student's t-test for paired samples based on a hypothesis that the results of measurements using two instruments are statistically not different. The test parameters are shown in Table 3. Potassium and uranium analyzed by the two instruments show small deviations close to magnitude of measurements errors. Concentrations of thorium established by the two gamma-ray spectrometers were found to be statistically identical.

Balek J.,Ustav Struktury A Mechaniky Hornin AV CR | Balek J.,Czech Technical University | Marek T.,Ustav Struktury A Mechaniky Hornin AV CR | Marek T.,Charles University | And 2 more authors.
Geoscience Research Reports | Year: 2014

České středohoří Mts. area has long been modeled by landslides. Just around the city Třebenice there are several active slope deformations. Mentioned landslide is exceptional because of its long-term activity disrupts just two linear structures. For this reason, the landslide was several times intensively investigated in the past and is therefore much better mapped than most surrounding areas. The aim of this paper is to summarize the historical and current developments in the landslide regarding its activity, its monitoring and various stabilization measures. In the modern history, the area was several times affected by landslide causing damages on railroad line and asphalt road. In the 70s and 80s line operation had to be stopped (Fig. 1). Therefore two remedy measures were realized. First one in 70s, was focused only on railway crossing area and may have decreased groundwater levels. Despite the implementation stabilization measures further landslide occurred in 1982 on a much greater extent than the previous one. In the response to this event was the construction of new measures aiming on one hand to reduce the groundwater level and on the other hand mechanically stabilize the landslide mass. Currently the railway body is considered stable, but this fact was never been verified by measurements. Trigonometric and extensometric measurements show displacements of some parts of landslide Aup to 30 mm per year (Fig. 3). Deformations are clearly visible on road surface. Moreover, small but permanent position changes in position of some reference points indicate, that some parts of the railway body may not be absolutely stable. It appears, that some parts of the rail stabilized housing show long-term movements in the direction of the slope. New precise leveling measurements were carried in order to check vertical stability of railway body.

Rockfall hazard is assessed using, which is one dimensional tool for assessing the protective function of forests against rockfall. Three sites where chosen to test the tool with different morphological and forest conditions. For each site, it was evaluated how the boulder size and forest composition affects the probability of the rocks to surpass the forested slope. The Rockfor. net was also used for back calculations of past event, which happened during the floods in July 1997 in the village of Bystřička in the Vsetínské vrchy Hills. In this case, also a partial quantitative risk assessment with suggestions for risk management was performed.

Blahut J.,Ustav struktury a mechaniky hornin AV CR | Klimes J.,Ustav struktury a mechaniky hornin AV CR
Geografie-Sbornik CGS | Year: 2011

This paper presents an international concept of landslide hazards and risk studies. Basic terms are noted along with their English and German equivalents. Significant differences among their definitions are discussed. Other components of landslide risk, namely elements at risk and vulnerability, are presented as are other related terms. Attention is focused on differences in meaning among the basic terms used in social, technical and natural sciences. Attention is focused on differences in meaning of the basic terms in social, technical and natural sciences outlining possibilities of overcoming those differences to facilitate communication among them.

Havelcova M.,Ustav struktury a mechaniky hornin AV CR | Bicakova O.,Ustav struktury a mechaniky hornin AV CR | Sykorova I.,Ustav struktury a mechaniky hornin AV CR | Weishauptova Z.,Ustav struktury a mechaniky hornin AV CR | Melegy A.,National Research Center of Egypt
Fuel Processing Technology | Year: 2016

Sub-bituminous coal and admixtures with polyethylene terephthalate were co-processed. The main objective of the study was to produce coke and to determine how ratios of input raw materials affected its structure. All main product yields (coke, tar, gas) were characterized by petrological and chemical methods. The addition of PET to coal in coking blends had impacts on coke yield, its true density, volume contents of fissures and mean reflectance, volume and surface of pores, and the formation of aromatic structures in the coke. However, the properties of coke and gas did not change significantly until 20% of the coal had been replaced with PET bottles in the coal charge. © 2016 Elsevier B.V.

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