The article provides the results acquired during the development of a magnetic circuit equipped with magnetic blocks assembled from NdFeB magnets with gradually increasing height. It presents the knowledge from the application of the new method of assembling these blocks and the achieved values of maximum magnetic induction in dependence on the distance from the surface of the blocks both for their different heights and for the different designs of the magnetic circuit in comparison with the values obtained for similar magnetic circuits with ferrite magnets., Václav Žežulka., and Obsahuje bibliografii
A brittle tectonic study has been carried out in the crystalline limestone and granite quarries near Vápenná village in the Rychlebské hory Mts. in the NE part of the Bohemian Massif. The quarries are situated along the Sudetic Marginal fault zone - the most important tectonic structure of the area. At the lo cality, the Sudetic Marginal fault separates Devonian crystalline limestones of the Branná group and Paleozoic granites of the Žulová pluton. Hundreds of measurements of joints and small-scale faults were taken in three limestone quarries on the west side of the fault. Kinematic indicators were observed as well. Equivalent measurements and observations have been performed on the fault east side in several small granite quarries. In the limestones three sets of fault have been identified (the W-E subvertical, the Sudetic NW-SE falling 45° to NE and the N-S falling 75° to W). The W-E direction of faults is the most importa nt direction there. There are two sets of faults in the granites (the subvertical Moravo-Silesian NE-SW and the Sudetic NW-SE). The NE-SW direc tion is dominant. There are almost none subhorizontal faults in the studied area., Lucie Nováková., and Obsahuje bibliografické odkazy
Resonance frequencies of unconsolidated sediments of the Iška alluvial fan (Ljubljana Moor basin) were derived using microtremor method. Free-field measurements were conducted in a grid with point spacing of approximately 250 m. The sediments frequency-thickness relationship, h = 202.97 f -1.139, was obtained on the basis of 107 microtremor measurements, six existing boreholes that reached the Pre-Quaternary basement and two seismic reflection profiles. The reliance of the obtained relationship was evaluated with the R2 coefficient, which shows a very good level of determination. The resonance frequency map reveals the existence of an N-S oriented deeper buried valley (maximum depth 119 m) in the Western part of the alluvial fan. The microtremor HVSR amplitude map does not show any specific spatial distribution pattern, with the exception of a relatively narrow band of low amplitudes located north of Iška vas. This is probably related to an area of severely fractured bedrock along the Mišji Dol fault. Map of the Quaternary sediment thickness and map of the Pre-Quaternary basement topography were constructed on the basis of the established relationship. The basement topography map shows rather steep western slopes of the buried valley down to deepest part, followed by a gradually ascending basement towards the Eastern part of the fan. The comparison of the obtained parameters a and b in frequency-thickness relationship with other sedimentary basins around the world reveals a small variation of b values, and a rather large range of a values, which implies that the parameter a is characteristic for certain geological areas. The results of this research will find use in constructing more accurate hydrogeological models and for assessment of possible sediments-structure resonance effects in seismic microzonation., Lovro Rupar and Andrej Gosar., and Obsahuje bibliografii
The sustainable ecology belongs to the most important issues today. In this field a use of recycled materials is of great interest to people. Consequently, incorporation of industrial waste, concrete and brick scraps and other rubbish into products for civil engineering use is very important. Certain results from experiments carried out in laboratory on standard samples are emerged in this paper. Since the material is not yet enough approved, three main targets are addressed. The first involves the behaviour of fiber reinforced concrete based on aggregates from various recycled material. Then the influence of distance among two or more fibers is observed. For completeness the results from shear tests are presented in the end of this paper., Jiřina Trčková and Petr Procházka., and Obsahuje bibliografii
The effect of temperature in underground mines is related to the geothermal gradients of rocks overlying the mining excavation. This may exceed the standards of comfort for human beings to work in an underground environment thus causing thermal discomforts and associated risk. In order to evaluate the influence of high ventilation temperatures on mine workers a mathematical model has been developed based upon the concept of heat transfer from the rock mass to the air flow in the underground environment. This model has been validated in the Noves Corvo underground copper mine, Portugal., Vidal F. Navarro Torres, C. Dinis Da Gama and Raghu N. Singh., and Obsahuje bibliografii
The research in question deals with problems of determining seismic P- and S-wave velocities for purposes of computing the elastic constants of a rock massif. This experimental study indicates various ways of measurement and its processing for different geological conditions. The experimental measurements were carried out on the surface of the studied rock massif, on the walls in workings, as well as on the surface in a quarry. The question of seismic pick-ups, geophones or piezo-electric transducers and the number of components required to identify P- and S-waves, is discussed. This is considered in connection with the choice and properties of the impact or piezo-electric seismic source. The result is a number of generalizing recommendations with respect to the measuring technique, inclusive of its use for determining the directional dependence of the elastic moduli., Roman Živor, Jan Vilhelm, Vladimír Rudajev and Tomáš Lokajíček., and Obsahuje bibliografii
The technique of assessing the failure of rigid overlying strata is applicable to deep mining with thick coal seams (a thickness of more than 1 m in the Ostrava-Karvina Coalfield), and in one case to longwall mining with controlled caving. The assessment of failure of rigid overlying strata makes it possible to distinguish whether the rigid overlying strata of rocks has been deformed or whether a strutting arch has been formed over the goaf below which is an area that is free from stress. Good knowledge of the mining, technical and geological conditions of a given site is a prerequisite for successful evaluation. There are advantages to utilising surface measurements for interpreting the effects of changes in rock mass, especially in areas of high overlying strata. The practical importance of failure assessment of overlying strata consists in determining the size of the mined-out area where the deformation of the rigid overlying strata occurred, which is dependent on the character of the rock mass. This paper is set in the context of the expected width of the goaf during deformation of rigid overlying strata within parameters that describe the mining and geological conditions of the locality. Changes in the area of the goaf, based the results of tensometric measurements, will also be placed in context., Eva Jiránková, Lubomír Staš, Vlastimil Kajzar and Hana Doležalová., and Obsahuje bibliografii
The aim of this paper is to show time-de pendent baseline variation between GPS stations situated in South-East Poland. This study was based on daily data analysis of selected GPS stations: WROC, GOPE, MOPI, KRAW and KATO. The start date o f the analysis is linked at every station with the beginning of its operation and the closing date of the operation is in 2006. The multiresolution signal decomposition method has been used to analyze the periodic terms of the time series of the above. The estimated trends enable further coordinate analysis as well as determination of site displacements at the study area., Mariusz Figurski, Krzysztof Kroszczyński, Paweł Kamiński and Marcin Gałuszkiewicz., and Obsahuje bibliografické odkazy
Monitoring of tectonic movements along three active faults of Dinaric (NW-SE trending) fault system in W Slovenia using TM 71 extensiometers was set up in 2004. After two and a half years of measurements clear trends of displacement were recorded. The average left-lateral displacement along a crack in the inner fault zone of the Idrija fault in Učja valley was reading 0.38 mm/year. Short term (10 months) rates were even greater and reached the value of 0.54 mm/year. Since the Idrija fault is considered generally to be dextral strike-slipping, the observed left-lateral displacement can be explained by variations in principle stress. Raša fault monitoring site at the foot of Vremščica Mt. established an average reverse uplift of hanging wall (SW) block of 0.24 mm/year and left-lateral displacement of 0.16 mm/year. Short term (9 months) vertical displacements reached the value of 0.53 mm/year. The inclined displacement is in agreement with geological and seismological observations. In the Postojna cave system two instruments were installed at the fault which extends parallely to Predjama fault zone. The average vertical displacement rate at Postojna 1 site was 0.01 mm/year. Both devices recorded similar reaction which can be attributed to 12 July, 2004 (Mw=5.2) earthquake with an epicentre 70 km away from the measuring site. Since there were no other stronger earthquakes in the vicinity and time span of monitoring, no other correlations were established with earthquake activity. The observed displacement rates along all three monitored faults of up to 0.5 mm/year are consistent with the regional deformation rate in W Slovenia established from GPS measurements which is of the order of 2 mm/year., Andrej Gosar, Stanka Šebela, Blahoslav Košťák and Josef Stemberk., and Obsahuje bibliografii