Using the FLAC3D numerical simulation method, the characteristics of mining stress evolution, fault activation patterns, and fault energy evolution characteristics are simulated and analyzed in the process of the footwall and hanging wall working face heading to a normal fault. The study shows that the fault cut off the mining stress propagation of overlying strata, and the stress blocking effect due to the fault is evident. When working faces head towards a fault, the abutment pressure and the vertical stress of the surrounding rock increase first and subsequently decrease. The abutment pressure of the coal wall and fault is highest when the distances to the fault are 40 m and 30 m for the footwall and hanging wall working faces, respectively. Moreover, the hanging wall mining stress is higher than the footwall mining stress. Fault activation in high-located strata precedes that in low-located strata when working faces head towards the normal fault. Energy is gradually accumulated before unstable fault events take place because of mining, and fault instability quickly releases a lot of energy. The mining stress concentration and fault activation due to faults easily result in rock bursts and mine seismicity, Wu Quan-sen, Jiang Li-shuai and Wu Quan-lin., and Obsahuje bibliografické odkazy
The Hronov-Poříčí Trough represents the easternmost part of the Trutnov-Náchod Depression. The NW-SE striking structure was formed due to the post-Cretaceous flexural folding and is filled with the Upper Cretaceous sediments. Both the NE and SW margins of the trough are bounded by flexures with the Upper Cretaceous strata dipping 40-60° towards the axis of the trough. The NE flexure is situated close to the parallel Hronov-Poříčí Fault Zone. Up to now, it is not fully known, in what extent the normal faulting was involved in the evolution of the structure. From the geomorphological point of view, the normal fault constraints of the trough seem to be acceptable, as the surface topography of its present margins exhibit many signs typical for fault scarps. However, the existence of a fault system bounding all round the Hronov-Poříčí Trough has not b een proved by any geological research. Hence the geophysical research was carried out on both sides of the NW part of the trough to support one of these hypothesis. Five geoelectrical profiles were measured in the area and the fault system was proved on the NE side of the trough. On the SW boundary the fault system was not found. Thus it seems, that the NE boundary is controlled by fault tectonics, whereas the SW boundary is rather formed by a simple flexure., Jan Valenta, Vladimír Stejskal and Petra Štěpančíková., and Obsahuje bibliografické odkazy
Permeability plays an important role in the field of geotechnical engineering. Under high temperature and high pressure condition, the physical-chemical and structure properties (such as decomposition, oxidation, dehydration, evaporation, phase transition etc.) of rock have obviously changing, which are significant affected the rock permeability. In order to analyze the influence of temperature and confining pressure on the permeability of rock (sandstones, siltstones and conglomerates) data for permeability was obtained from the literature. The results indicate that temperature and confining pressure have great influence on the permeability of rock, especially for sandstone. There is a threshold temperature and when the heating temperature is lower than the threshold temperature, the permeability of sandstone gradually increases with an increase in temperature. When the heating temperature is higher than 300 ºC (especially 400 ºC), the permeability rapidly increases. The permeability of sandstone decreases gradually with the confining pressure increases. This study of the relationship between rock permeability and temperature and confining pressure lays a foundation for investigations of multi-disciplinary issues regarding high temperatures and high pressures and it can be used for the study of petroleum storage and safe nuclear waste disposal., Zhenlong Ge, Qiang Sun and Wenping Li., and Obsahuje bibliografii
In the frame of advanced studies of coal structure the temperature conditions of coal origin were investigated through thermal stability of aluminum complexes in coal substance. These compounds were discovered by solid-state nuclear magnetic resonance measurements of 27Al as a part of coal substance closely bonded to organic mass of coal. In obtained spectra, Al-hexaphenoxide and Al-tetrahydroxy-diphenoxide complexes were identified. These complexes were further prepared and their thermal stability tested by thermal analysis method. It was found that a) they can originate under room temperature and atmospheric pressure and b) they are thermally stable only up to approximately 85 or 95 °C. As both Al-hexaphenoxide and Al-tetrahydroxy-diphenoxide complexes are the integrated constituents of coal substance it can be deduced that, in the beginning, coal was formed under very mild thermal conditions. As investigated materials, coals and clays from the Czech basins and gagatite from Poland were measured., Pavel Straka and Jana Náhunková., and Obsahuje bibliografii
This paper focuses on the impact of changes in temperature on one bay of St Vitus’ Cathedral in Prague Castle. The objective of the study is to simulate as correctly as possible the distribution of temperatures in the structure, and then to compute the thermal dilatation movements. Theoretical simulation of dilatation movements involves simulating the temperatures in the structure and then computing the displacements. Insolation and changes in air temperature around the structure are included in the temperature simulation. The computed temperature fields are used as a loading for computing the forces and deformations of one bay of St Vitus’ Cathedral. The theoretical deformation values obtained by means of the 3-D finite element model were compared with the measurements. The computed surface temperatures were also confronted with the surface temperatures measured in the interior and on the exterior of the cathedral. The results obtained from the simulations correspond well with the measured surface temperatures and deformations., Pavel Beran, Jiří Máca and Petr Fajman., and Obsahuje bibliografii
Polyaniline/montmorillonite (PANI/MMT) intercalate pressed into pellets using the pressure 28 MPa has been prepared in order to achieve two-dimensional conductivity which is close to pure PANI, however with improved mechanical and thermal stability (due to the presence of silicate). Structure-conductivity relationship has been investigated using X-ray diffraction analysis and diffraction patterns obtained from two perpendicular planes revealed the strong texture. The structural anisotropy led to the anisotropy in conductivity, which is much stronger for PANI/MMT than for pure PANI pellets. Anyway, the inplane conductivity is of the same order for both PANI/MMT and pure PANI pellets. The anisotropy factor, that means the ratio of in-plane conductivity and conductivity in the direction perpendicular to the pellet plane, was 328 (PANI/MMT pellet) and 6.7 (pure PANI pellet), respectively., Jonáš Tokarský, Kateřina Mamulová-Kutláková, Lucie Neuwirthová, Lenka Kulhánková, Vítězslav Stýskala, Vlastimil Matějka and Pavla Čapková., and Obsahuje bibliografii
The goal of this study is to determine the validity of morpholineaments network that was inferred based on morphostructural analysis of digital elevation model (DEM), by crosschecking with documented faults. The test field has been spread over the exploitation areas in the Zlaté Hory ore district. Various morphometric analyses such as slope, aspect, first directional derivative, gradient operator, combination of altitude and shaded relief, were chosen as particular tools of the morphostructural analysis. The results of each analysis were compared with the results of structural-tectonic mapping. The inferred morpholineaments network was compared with mining maps of the scale 1:500, which provide detailed information about tectonic deformation of rock massif in the area of interest and were used to image fault traces on the surface. The validity of inferred morpholineaments network was determined by authorized software SROV_TEKT, developed by the authors. The morpholineaments network resulting from the morphostructural analysis and tested by this software overlaps at 83 % of the documented main faults in the mines., Jan Jelínek, František Staněk, Jan Thomas, Tomáš Daněk and Jiří Mališ., and Obsahuje bibliografii
The case study of a ground steps creation due to underground mining in Upper Silesia Basin, where for many years was conducted intensive hard coal extraction has been presented in this paper. This type of linear discontinuous deformations is considered as an important threat to the surface building constructions and elements of underground technical infrastructure. This threat is even more important, that presently still we do not have methods for predictions of such phenomena, and protection of building constructions against such damages is difficult, if not impossible. On the basis of the analyzes results shown in the paper, the following factors were pointed, that favor the formation of mining-induced ground steps: the presence of fault outcrops in the vicinity of extraction fields, multiple extraction in several coal seams led to the same border and large values of tensile horizontal strain., Piotr Strzałkowski and Roman Ścigała., and Obsahuje bibliografické odkazy
GNSS meteorology is the remote sensing of the atmosphere (particularly troposphere) using Global Navigation Satellite Systems (GNSS) to deliver information about its state. The two currently available navigation satellite systems are the Global Positioning System (GPS) and the GLObal'naya NAvigatsionnaya Sputnikovaya Sistema (GLONASS) maintained by the United States and Russia, respectively. The Galileo navigation satellite system, which is under supervision of the European Space Agency (ESA), is expected to be completed within the time frame of a few years. Continuous observations from GNSS receivers provide an excellent tool for studying the earth’s atmosphere. The GNSS meteorology has reached a point, where there is a need to improve methods not only to compute Integrated Water Vapor over the GNSS receiver, but also to investigate the water vapor distribution in space and time (4DWVD). Since 2008, the new national permanent GNSS network ASG-EUPOS (98 stations) has been established in Poland. 17 Polish stations equipped with GNSS receivers and uniform meteorological sensors work currently in the frame of the European Permanent Network. This paper presents the concept of the integrated investigations for NRT atmosphere model construction based on the GNSS and meteorological observations from ASG-EUPOS stations., Jarosław Bosy, Witold Rohm and Jan Sierny., and Obsahuje bibliografii