Four precise leveling campaigns has been carried out in Poland, and for several years there is a functioning system of permanent GNSS stations determining the height of network points. On the basis of these data, several variants of vertical crustal movements models have been developed (Wyrzykowski, 1987; Kowalczyk, 2005; Kontny and Bogusz, 2012). In order to develop a kinematic model of vertical crustal movements, one of the possibilities is an adjustment of the network formed simultaneously with the leveling data and GNSS stations data. The main problem is a need to identify fiducial points between the datasets. This problem can be solved by creation of coherent database containing attributes of both types of data and automatization of the joint point identification process. The article shows the results of such identification process, depending on the amount of data, on the example of the area of Poland. and Bednarczyk Michal, Kowalczyk Kamil, Kowalczyk Anna.
illustroval Pavel Körber ; historická čásť od Jana V. Krecara and Na obálce: K upomínce na "Hotel Victoria" Jungmannova třída v Praze, Otto Welzer-hotelier
The aim of this contribution is a detection of geodynamic effects at a very distant geodynamic station GOPE in the middle of Europe (Czech Republic). Strong earthquake, followed by strong indirect effect (tsunami), with the parameters (26.12.2004, 00:58:53.4 UTC, mag. 9.0, latitude 3.295N, longitude 95.982E, depth 30 km) was analysed from the records of tidal gravimeter (ASK No.228) with respect to free oscillations of the Earth (spheroidal component), by spectral analysis. This analysis detected significant vertical component of GOPE position in relatively long time interval (several hours) after the beginning of the earthquake. To verify the geodynamic tendencies of the GOPE station movements the GPS observations were analysed at the same time interval. We had data with 1s sampling interval at our disposal. For analysis we used PPP (Precise Point Positioning) method which produces absolute values of the coordinates in the ITRF 2000 system. Possible correlations between the results of both ways have been searched. We concentrated consequently to the determination of mean displacements and on the attempt of detection of some amplitudes of following free oscillations of the Earth. Mean change of position of the station GOPE during and after the earthquake, detected from the results of GPS observations is about 1.5 cm in horizontal and height components. Amplitude magnitudes for frequencies of the free oscillations of the Earth, which were analysed either from gravimetric data or from the GPS data, are equal in order. The study of free oscillations of the Earth by application of GPS is completely new. Studying of free oscillations is usualy accomplished by data from seismometers, tiltmeters or superconducting gravimeters., Petr Lukavec, Jan Kostelecký, Antonín Zeman, Jakub Kostelecký, Jan Kouba and Vojtěch Palinkáš., and Obsahuje bibliografii
Four space geodesy techniques, namely VLBI, GPS, SLR and Doris, produce Earth orientation parameters (EOP) and station coordinates independently of each other. A method to combine them in a non-rigorous way (as described elsewhere) was modified by implementing Vondrak’s smoothing. It replaces a simple constraint to tie EOP at adjacent epochs by a more general expression defining smoothness of the resulting curves. This gives the method better stability of derived EOP. The new method was tested on GPS, VLBI and SLR data covering a one-year interval. The results were compared with the results of the original method and with the IERS c04 solution. The former indicates the effect of modification while the latter shows differences of this particular solution from the official IERS series, Vojtěch Štefka and Ivan Pešek., and Obsahuje bibliografické odkazy
Three different metakaolins processed by a Portuguese factory were studied aiming to assess the influence of chemical and mineralogical composition of metakaolin on mortar characteristics. Mineralogical analysis of both the fine and clay fractions was carried out by X-ray diffraction. Chemical composition (major elements) was analyzed by X-ray fluorescence. Mineralogical composition reveals some significant differences between the studied samples, in both analyzed fractions, metakaolin 2 being richer in kaolinitic minerals. From a chemical point of view, siliceous content is always high (aroun d 60 %) as well as Al2O3 content (around 30 %); once again metakaolin 2 is the one richer in Al2O3 and poorer in sodium and potassium. Metakaolin from the three different batches was incorporated in lime mortars in order to produce a pozzolanic reaction and hence enable them to harden in high relative humidity conditions or, when access to CO2 is limited, as in the case of mortars supporting glazed tiles. Mortars with the same volum etric ratio were tested for flexural and compressive strength at ages of 28 and 90 days, and the module of elasticity was dete rmined. A relation between the mechanical strength achieved by lime mortars with the addition of metakaolin from different batches and metakaolin mineral and chemical composition was assessed. The knowledge of the influence of the metakaolin com position on the strength of the mortars is an important step in improving their performance and extending their application., Ana Luisa Velosa, Fernando Rocha and Rosário Veiga., and Obsahuje bibliografické odkazy
The problem of bumps occurrence in deep mines during the long wall mining appears to be one of the most serious one in the design of engineering of mining. The bumps are caused for various reasons, but basically it is an aftermath of the accumulated energy, which is released under some unfavorable conditions. In this paper the influence of given dislocations and their slope in a coal seam are studied based. The numerical tool is the free hexagon method. This method belongs to a set of discrete element methods and enables us to define and calculate stresses in a natural way along the interfacial boundaries of adjacent particles (elements). Since the bumps are affected by a possible slip along the dislocations, dynamical response has to be taken into account. The velocity of excavation of the mine is considered by successive change of values of Eshelby’s forces on the face of the wall., Petr Pavel Procházka, Jiřina Trčková and Tat Seng Lok., and Obsahuje bibliografii
Surface deformation due to underground exploitation affects the safety of overlying structures. Forecasting can predict risks to surface structures and facilitates actions designed to improve their resilience and reduce the potential impact of mining activities. However, forecasting accuracy is limited. Therefore, in practice, model parameters are determined within a certain margin to ensure that critical values of deformation indicators for surface objects are not exceeded. For economic reasons, it is important to minimize these margins while also ensuring that safety is maintained. One important factor influencing forecasting accuracy is the uncertainty in deformation model parameters used for calculations. Therefore, it is critical to adopt an appropriate methodology for determining and addressing the uncertainties in deformation model parameters used in forecasting. This study presents methods for estimating the Knothe's model parameters needed to forecast surface deformation caused by underground mining and defining the uncertainties in those forecasts. Depending on the parameter uncertainties, one of two methods for propagation is proposed: the Monte Carlo method or the law of propagation of uncertainty. Using this approach, it is possible to account for uncertainty and reduce forecast margins. A case study of hard coal mining in the Upper Silesian Coal Basin region of Poland is presented., Wojciech Gruszczyński, Zygmunt Niedojadło and Dawid Mrocheń., and Obsahuje bibliografii
The influence of particle shape (aspect ratio) on the intrinsic viscosity is investigated, taking three Czech kaolin products (floated kaolins) as paradigmatic examples. An average aspect ratio is obtained for each kaolin from a comparison of particle size measurements using sedimentation and laser diffraction. The intrinsic viscosity is obtained by a multistep procedure: firstly, flow curves are recorded for each kaolin with the optimum deflocculant concentration, secondly, the (apparent) relative viscosities read off from the flow curves are plotted against the kaolin volume fraction and, thirdly, these data are fitted using the Krieger relation to obtain the intrinsic viscosity in the asymptotic dilute limit. It is shown that the data determined with the method proposed are within the Jeffery and Brenner bounds and that an average aspect ratio of about 20 (17-22) results in an intrinsic viscosity of about 10 (7-13), compared to 2.5 for spherical particles. Although currently th e measurement precision is not suffi cient to seriously assess the influence of Brownian motion, the method can principally be used to predict the intrinsic viscosity when the average aspect ratio of the system (and its particle size distribution) is known, and vice versa., Eva Gregorová, Willi Pabst and Jean-Baptiste Bouchet., and Obsahuje bibliografické odkazy
The vault in Vladislav Hall is a structural masterpiece of great historical value. Its structural analysis revealed that the permanent load exerted by its self weight is uniformly transmitted into the vaults and ribs without any potential crack appearance. The topical issue, however, is its response to temperature changes with respect to actual effects. Computations show that temperature changes may cause problems., Petr Fajman, Jiří Máca and Pavel Beran., and Obsahuje bibliografii