The study concentrates on analysis of heterogeneous rock mass deformations in the final years of underground coal extraction and during the revitalisation period after the end of mining. The research has been carried out in the Walbrzych Coal Basin where underground mining ceased at the end of the 20th Century. In the paper results of initial stages of ground deformation studies on a fragment of the Walbrzych mining grounds concerning analysis of benchmark height changes in a selected levelling line has been described. The results indicate ground subsidence in the period immediately after end of coal extraction and change to a steady uplift of the ground a few years later (2000-2008). Abnormal changes of heights in tectonic fault zones have also been observed. These could be related to heterogeneous rock mass reaction during the revitalisation period., Jan Blachowski, Stefan Cacoń and Wojciech Milczarek., and Obsahuje bibliografii
Repeated geodetic observations were applied in mining location Louky near Karviná to detect surface changes from undermining in complex geo-mechanical conditions. Analyses of the subsidence magnitude and the length and direction of horizontal displacements showed that the subsidence trough was formed unevenly not only due to the position of the exploited local longwall panels and their different size but also showed a notable effect of the dominant tectonic fault. The significantly uneven development of the subsidence trough negatively affects line constructions. Terrain deformations of the road and stream pipeline were computed and classified into the building site categories according to the Czech standard ČSN 73 0039. The course of individual deformations in the monitored locality is influenced by a complex geo-mechanical situation. While the course of the subsidence curves is continuous at the observed pipeline and the classification of individual sections into building site categories corresponds with that, the road profile points out a more complex development of surface deformations. At the end of the observed period, 5 % of the profiles’ sections fell into category III (medium intensity), 49 % into category IV (moderate intensity) and 32 % stayed in category V (very moderate intensity of mining effects).
Secondary deformations are ground movements occurring in areas of ceased underground mining. These are associated with delayed readjustment of rock mass resulting in subsidence, discontinuous deformations (sinks, cracks, etc.) due to destruction of underground, usually shallow, workings, and elevation of ground surface in response of rock mass to rising groundwater levels following the end of mine water drainage. Comparative analysis of secondary deformations in two former mining areas in the first period after cessation of underground hard coal mining is the subject of this study. We used ERS-1/2 and Envisat satellite radar interferometry data processed with PSInSAR technique and GIS to map vertical (in satellite’s line of sight, LOS) movements of the surface and analyse them in relation to location of coal fields and underground water table rise. In the study, two areas have been compared, the Ostrava city in the Czech part of the Upper Silesian Basin and the Wałbrzych Coal Basin in Poland. The results of analyses based on the results of PSInSAR processing between 1995 and 2000 for the Wałbrzych site indicate uplift (up to +12 mm/year) in closed parts of coal fields and subsidence (up to -8 mm/year) in areas of declining mining. Results of PSInSAR analysis over the Ostrava site indicate decaying subsidence after mine closures in the rate of up to -6 mm/year during 1995-2000. Residual subsidence and gentle uplift have been partly identified at surroundings of closed mines in Ostrava from 2003-2010 Envisat data. In Wałbrzych gentle elevation has been determined from 2002 to 2009 in areas previously subsiding. and Blachowski Jan, Jiránková Eva, Lazecký Milan, Kadlečík Pavel, Milczarek Wojciech.
The macrozoobenthos in saline pools at dumps in a former coal mining area was studied over a period of two years. Due to specific environmental conditions these pools are unique in the Czech Republic. Extremely high values of salinity (up to 11‰) along with a low concentration of dissolved phosphorus (0.01-0.1 mg.l-1) are typical of some of the water in this area. The pools were grouped into three categories based on their conductivity values and treated using cow dung, municipal wastewater treatment sludge and inorganic NPK (nitrogen-phosphorus-potassium) fertilizer at doses recommended for carp ponds. The application of fertilizer had a positive effect on the density and biomass of all the groups in the macrozoobenthos. The highest and the lowest increases in macrozoobenthos biomass were recorded after the application of NPK and cow dung, respectively. However, the application of fertilizer had no effect on the diversity of macrozoobenthos. Chironomus aprilinus, recorded in the Czech Republic for the first time, inhabited all pools with conductivity ranges of between 5,000-16,000 µS.cm-1. The density of C. aprilinus larvae increased with increasing salinity reaching a maximum of about 17,083 ind.m-2 (biomass - 82 g.m-2). Analysis of C. aprilinus phenology revealed a bivoltine pattern with the summer generation of larvae reaching a maximum in June-July and the overwintering generation in October to November., Josef Matěna, Iva Šínová, Jakub Brom, Kateřina Novotná., and Obsahuje bibliografii
Magnetotelluric (MT) and audio-magnetotelluric (AMT) methods were applied to clarify the deep geological structure in a coal-mining area in Kushiro, southeastern Hokkaido, Japan. These methods are effective in surveying to deep. Onedimensional inversion was applied to the measurement data obtained in the MT and AMT surveys to estimate the resistivity distributions in the study area. In addition, the one-dimensional inversion method was improved to obtain accurate results by including a smoothing factor and Akaike’s Bayesian information criterion. The inversion method revealed that the lowresistivity zones at depths between 100 and 120 m below sea level correspond with the Yubetsu coal-bearing formation and clay layer, and the thickness of Cretaceous strata was estimated to be more than 4000 m. Finally, the dip of the Osotsunai fault was estimated., Hisafumi Asaue, Misahito Sasahara, Toru Yoshinaga, Yuzo Obara, Kagemi Ushida and Hiroyuki Matsumoto., and Obsahuje bibliografii
Brown coal open pit mining in the basin under Krušné Hory Mts. came to contact with slopes of the mountains, and a problem of the stability in high and steep slopes in the crystalline rock became an important question. The question concerns Jezeří Castle built on the top of one of the hills in a most endangered section where even a supporting pillar in the sediments under the slope toe was left to support the slope. As a result, an extensive monitoring program regarding deformations was initiated in the region. The program involved several methods and some important results are discussed. The results that are displayed concern mainly measurements done in geophysical tiltmeter stations in two underground galleries driven into the two steep slope sections showing most dangerous situation, as well as extensometers located in the same locations. Long-term monitoring revealed a tectonic deformation process of a natural origin that is registered as slow and systematic tilts. Besides, it revealed several periods of anomalies that are of basic importance. During a long period of observation from 1982 till 2005 three important deformation anomalies were registered: the event of 1994, the event of 2002, and the event of 2003/2004. The first and the third event have been classified as of a large regional character that affected a wide mountainous area and could be interpreted as a tectonic impulse originating within the mountainous structure of the so called "Dome of Hora Svaté Kateřiny". The second event has been considered different, strictly connected with extreme precipitation of August 2002. The anomaly was evidenced even deep in the crystalline, so that it could not be seen as of a superficial character only. The movement which was registered at that time was oriented right into the pillar supporting the slope., It is concluded that it was a short manifestation of instability in the critical profile "Jezeří - pillar", which stresses the important stabilisation function of the supporting pillar without which the profile will be probably destabilised., Blahoslav Košťák, Bohumil Chán and Jan Rybář., and Obsahuje bibliografii
The research is focused on the feasibility analysis of a numerical model describing the field of strains generated by mining-induced subsidence caused by a deep underground coal extraction, which may contribute to the formation of Earth fissures. The finite elements method and Knothe’s theory were used in the research. The geomechanical modeling was applied for defining zones of strains and maximum horizontal deformations of the terrain. Knothe’s theory was employed for defining boundary conditions of the geomechanical model. The parameters of the empirical and geomechanical models were scaled out on the basis of geodetic surveys in the mining area. The results of geomechanical modeling were compared with the geodetic surveys to select the best model. The presented research confirmed high congruence between the results of modeling with the finite elements method and observations of vertical movements on the surface. The results of modeling also confirmed the assumed highest stress in areas where earth fissures were observed. The proposed solution may be a new research tool applicable to areas where earth fissures potentially occur. and Malinowska Agnieszka A., Misa Rafał, Tajduś Krzysztof.
Permeability refers to the ability of coal to transmit gas when a pressure or concentration gradient exists across it. The permeability of coal is dependent upon factors that include effective stress, gas pressure, water content, disturbance associated with drilling and matrix swelling/shrinkage due to adsorption/desorption. A programme of laboratory tests were conducted on coal samples from the Bulli seam for evaluating the permeability and drainability of coal. Two different types of permeability apparatus were used in this study. The methods of permeability testing of coal under different triaxial conditions are discussed. Permeability testing of the Bulli seam coal with N2 is described. The laboratory test results were found to be in agreement with the calculated permeability values, Naj Aziz, Ting Ren, Jan Nemcik and Lei Zhang., and Obsahuje bibliografii
In the article the results of registering seismic events located under mining coal seam are presented. Such mining tremors have occurred in several Polish mines. The geological and mining conditions affecting the induction of that type of seismic events are shown. The mechanisms of deep seismic events (more than 1000m) triggered by mining are discussed in relation to regional geology. The most deep mining seismic events in Upper Silesia were related to regional geological structures focusing stress (e.g. syncline) or tectonic structures (younger faults), where mining stresses were only additional factor to trigger strong regional seismic events. The tremors were characterized by a shear mechanism in the source (double-couple forces). Tremors located directly under the performed operation, usually characterized by an uniaxial tension mechanism, associated with the regional tension axis and the space created during the operation of the coal seam, causing pushing loaded rock-mass into new gobs. Proposed methods of seismic monitoring for case of seismic events location under mining coal seam are discussed., Grzegorz Mutke., and Obsahuje bibliografii