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
The irregular distribution of stress in rock mass is a decisive factor for the origin of rock bursts. Besides, a sound knowledge of stress distribution is very important in the excavation of mine workings. Stress state is affected both by natural stress, including the gravitational, tectonic, hydraulic and residual stress and the stress induced by mining operations. Natural stress fields are defined by their geological structure and rock properties. It is important in mining practice to understand that there is a close relationship between recent and residual tectonic stress, as defined by tectonic evolution and tectonic structure. Since 1994, a large number of horizontal stress measurements have been carried out at a depth of 600 m to 800 m under the surface. The application of the results obtained from the measurements of stress and their comparison with the results of structural analysis and their generalization for the Karviná subbasin can be an important contribution to optimize the timespace designs of the mining activity., Petr Waclawik, Jiří Ptáček and Radomír Grygar., and Obsahuje bibliografii