Assuring the stability of underground headings in order to fulfill their technical functions without any disturbance and provide a safe workplace for mining staff seems to be a fundamental issue in mining activity. In recent years, rockbolts: bar or cable have been most frequently applied as a means of reinforcement. Such a construction is often referred to as a stand-and-roofbolting support. The paper presents sample results of monitoring stand-and-roof-bolting support systems selected from numerous research projects carried out by the authors. The results discussed below are based on the measurements of the strength parameters of rocks in the laboratory and in-situ research, convergence of underground excavations, forces in rockbolts, separation of roof rock strata tested with extensometric probes, telltales and endoscopes, as well as steel yielding support frames load tested with dynamometers. The complex measurements of stand-and-roof-bolting supports along with specifications of geological, mining and geomechanical conditions allowed to formulate a proper evaluation of support behavior and its effectiveness for particular conditions., Zbigniew Niedbalski, Piotr Małkowski and Tadeusz Majcherczyk., 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